XC2000 Family AP16180 XC2000 Sensorless Fieldoriented Control Application Note V 1.0, 2010-09 Microcontrollers Edition 2010-09 Published by Infineon Technologies AG 81726 Munich, Germany © 2010 Infineon Technologies AG All Rights Reserved. LEGAL DISCLAIMER THE INFORMATION GIVEN IN THIS APPLICATION NOTE IS GIVEN AS A HINT FOR THE IMPLEMENTATION OF THE INFINEON TECHNOLOGIES COMPONENT ONLY AND SHALL NOT BE REGARDED AS ANY DESCRIPTION OR WARRANTY OF A CERTAIN FUNCTIONALITY, CONDITION OR QUALITY OF THE INFINEON TECHNOLOGIES COMPONENT. THE RECIPIENT OF THIS APPLICATION NOTE MUST VERIFY ANY FUNCTION DESCRIBED HEREIN IN THE REAL APPLICATION. INFINEON TECHNOLOGIES HEREBY DISCLAIMS ANY AND ALL WARRANTIES AND LIABILITIES OF ANY KIND (INCLUDING WITHOUT LIMITATION WARRANTIES OF NON-INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OF ANY THIRD PARTY) WITH RESPECT TO ANY AND ALL INFORMATION GIVEN IN THIS APPLICATION NOTE. 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AP16180 XC2000 Sensorless Fieldoriented Control XC2000 Revision History: V 1.0 2010-09 Previous Version(s): Page Subjects (major changes since last revision) – This is the first release … Trademarks We Listen to Your Comments Is there any information in this document that you feel is wrong, unclear or missing? Your feedback will help us to continuously improve the quality of this document. Please send your proposal (including a reference to this document) to: [email protected] Application Note 3 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 2.1 2.1.1 2.1.2 2.1.3 2.1.4 Theory of Sensorless Field Oriented Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 DC Motor Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Open Loop Voltage Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Closed Loop Torque Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Closed Loop Speed and Torque Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 List of Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Voltage Equation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Induced Voltage: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Mechanical Friction: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Mechanical Equation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Angle: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Speed in revolutions per minute (rpm): . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Space Vector Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Scaling: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Reference Vector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Sampling Period Ts: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Volt-Second Balancing: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Phase Current Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Limitations of Phase Current Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 FOC Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Stationary and Rotating Reference Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Clarke Transform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Park Transform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Inverse Park Transform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Summary Transformations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Sensorless FOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Flux of stator ψs: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Stator Voltage Equation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2 2.2.1 2.3 2.3.1 2.4 2.4.1 2.4.2 3 3.1 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.2.6 3.3 3.4 3.5 3.6 3.6.1 3.6.2 3.6.3 3.6.4 3.7 3.8 3.8.1 3.8.2 Implementation of a Sensorless FOC using the XC2236N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Software/Hardware Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scheduler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Statemachine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IDLE State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . STOP State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ramp-down State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Emergency Stop State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CAPCOM6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ADC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CAPCOM2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Misc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VDC and Poti . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Interrupt Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Variable Definition and Administration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DAvE Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . System IC TLE7184F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Application States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Motor Ramp-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Running state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Application Note 1 15 17 18 18 19 21 21 21 22 22 23 24 25 25 25 25 25 26 27 27 28 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control 3.8.3 3.9 Motor RAMP-down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 CPU Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 4 4.1 4.1.1 4.1.2 4.1.3 4.1.4 4.1.5 4.1.6 4.1.7 4.1.8 4.1.9 4.1.10 Communication Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MultiCAN Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Program Flow XC2236N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Command Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Receiving a CAN Message and Command Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transmitting a CAN Message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Command SET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Command GET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Button Start, Stop, Ramp Down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scope Buttons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oscilloscope and Progress Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Status Flags and Display Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 29 29 30 30 30 30 31 32 32 32 33 5 5.1 5.2 5.2.1 5.2.2 5.2.3 Configuration and Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Excel Sheet and defines.h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Drive Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Monitoring the Startup Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Example Fan: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Example Fan: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Monitoring the Runtime Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 34 35 35 35 36 36 38 6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Application Note 2 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Introduction 1 Introduction The Field Oriented Control (FOC) method described in this document is aimed at the target market for cost sensitive drives, such as fans, pumps, compressors and geared motors. In automotive solutions the sensorless FOC is used as redundant substitution if the sensor driven system fails. One other driving factor for a sensorless FOC on BLDC or PMSM is decreasing the system cost: sensors can generate problems in manufacturing and reliability, they require special wiring harnesses and connectors which increase the overall system cost. The other driving factor is the significant improvement of energy efficiency of a motor. The FOC methode allows to bring the efficiency up to 95%. This has a big impact on power consumption, motor dynamics, heat dissipation and noise. As an example fans and pumps in a lot of applications must operate very silently, otherwise the produced solid-borne sound distributes in water or air pipes within the whole environment. Usually this leads to concepts with sinusoidal currents in the motor coils. The limitation of the described methods is the single shunt current measurement which cannot guarantee a steady control under all circumstances. Thus the method is not suitable for high dynamic loads and positioning systems. Of course the algorithm can be adapted to 3-phase-shunt measurement which does not have this limitation. Application Note 3 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Theory of Sensorless Field Oriented Control 2 Theory of Sensorless Field Oriented Control This chapter is intended to give an overview about the theory of the sensorless Field Oriented Control (FOC) of permanent magnet syncronuous motors (PMSM). The control scheme which has been implemented at XC878 and XE164 is based on this theory. The implementation details are described in Chapter 3. Before describing the FOC theory in detail, we begin some background information on motor control. 2.1 DC Motor Control The DC motor consists of a permanent magnet which builds the stator and a coil mounted at the rotor. A mechanical commutator is needed in order to feed the current to the coils. This commutator will cause the current to be oriented according to the field of the permanent magnets at the stator. Figure 1 DC Motor The DC Motor is controlled by the voltage at the rotor coils and the current is proportional to the torque of the motor. The speed of the motor depends on the voltage and the torque. The nominal speed (ωnom) and torque (mnom) are defined in the following equations: v–i⋅R ω nom = ------------------Kc (1) m nom = K c ⋅ i (2) The time constants of speed and current control are very different. A control cascade structure for speed and current control can be utilized. 2.1.1 Open Loop Voltage Control In an open loop voltage control, there is just a reference voltage which will cause the power inverter to generate a given voltage at the motor. The mechanical load influences the speed and the current of the DC motor. DC Motor Vref Figure 2 V Power Stage Open Loop Voltage Control Application Note 4 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Theory of Sensorless Field Oriented Control In steady state, the torque can be described as follows: v – K c ω stat m stat = K c ⋅ -------------------------R 2.1.2 (3) Closed Loop Torque Control The torque control loop requires the measurement of the motor current with a current sensor; e.g. a shunt resistor. In general, the torque is proportional to the current. mm = Kc ⋅ i (4) As a result, a PI controller can be used for current control. The actual current, measured by the current sensor will be controlled to converge to the reference current. This can be done only by changing the reference Voltage (Vref) of the power stage. Please see following figure for details: DC Motor Iref + - eI Current Control Vref V Power Stage I mload Iact Current Sensor Figure 3 Closed Loop Torque Control 2.1.3 Closed Loop Speed and Torque Control For a speed controlled DC motor, a cascaded control structure can be used, because the speed change requirement is much slower than the one for the current. The speed control requires a speed sensor; e.g. a tachometer and the current control requires a current sensor. The output of the speed control is the reference current for the current control. Usually a PI controller is used for speed and current control. DC Motor ωref + - eω Speed Control Iref + - eI Current Control Vref Power Stage V ω I mload Iact ω act Figure 4 Current Sensor Speed Sensor Cascaded Speed and Current Control Application Note 5 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Theory of Sensorless Field Oriented Control 2.1.4 List of Equations The mechanical and electrical equations of the DC motor are valid for the Permanent Magnet Synchronous Motor (PMSM) as well. In the following, a set of equations is listed, which will be used later in this application note. Voltage Equation: di + R ⋅ i = v – v bemf dt (5) v bemf = K c ⋅ Ψ ⋅ ω (6) m Friction = r Friction ⋅ ω (7) L⋅ Induced Voltage: Mechanical Friction: Mechanical Equation: J⋅ dω = m m – m Load – m Friction dt (8) Angle: ∫ ω dt (9) ω n = 60 ⋅ -----2π (10) ϕ = Speed in revolutions per minute (rpm): 2.2 Space Vector Modulation In this section, the modulation of a three leg voltage source inverter is described. This type of inverter contains six MOSFETs or IGBTs which act as switches. The switches connected to the positive supply rail are called high side switches (hs) and the switches connected to the negative rail of the power supply are called low side switches (ls). In the following figure, a block diagram of a three leg voltage source inverter can be seen: U + V W V hs VDC U ls N - Figure 5 W Three Leg Voltage Source Inverter By switching the high side and low side switches on and off, there are eight states possible, which do not cause cross currents inside the leg itself, but allow a current flowing to and back from the motor. Application Note 6 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Theory of Sensorless Field Oriented Control State Uhs Uls Vhs Vls Whs Wls 000 (passive) OFF ON OFF ON OFF ON 100 (active) ON OFF OFF ON OFF ON 110 (active) ON OFF ON OFF OFF ON 010 (active) OFF ON ON OFF OFF ON 011 (active) OFF ON ON OFF ON OFF 001 (active) OFF ON OFF ON ON OFF 101 (active) ON OFF OFF ON ON OFF 111 (passive) ON OFF ON OFF ON OFF The states can be seen as vectors in the space vector diagram of the coordinates U, V and W. There are six active and two passive vectors. The space vector diagram of a U-V-W system contains six sectors (A, B, C, D, E, F). N S S N 0] [1 1 0] [01 N C [011] D B [100] F E N S S N 1] [0 0 [10 1] N S Figure 6 S A Space Vector Diagram of a U-V-W System The magnetic field (flux) of a three phase PMSM can be represented in a U-V-W space vector diagram. In Figure 6, the flux is simplified by a magnetic dipole. Whereas the stator coils are fixed in their position, the flux rotates dependent on the sector of the hexagon. In this case, the voltages at the three coils correspond to the values of U, V and W. The resulting vector corresponds to the flux of the stator coils. V VU = vU ⋅ e U VV = vV ⋅ e V = vU ⋅ e W j0 + vV ⋅ e vU = 2/3 VU vV = 2/3 VV vW = 2/3 VW j0 j 2π 3 VW = vW ⋅ e Figure 7 Scaling: V = VU + VV + VW j 4π 3 j 2π 3 The maximum length of the space vector is: + vW ⋅ e j 4π 3 |V|max = VDC Space Vectors in Complex Numbers Application Note 7 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Theory of Sensorless Field Oriented Control 2.2.1 Reference Vector The reference vector Vref represents the resulting magnetic stator field (flux). It is defined by the following equation: V ref = V ref ⋅ e jϕ (11) It is rotating in space with the speed ω : ω = 2π ⋅ f (12) The reference vector can be approximated by two active vectors (e.g. V1 and V2) and one zero vector (V0). The plane is dissected into six sectors and the angle ϕ is transformed into the relative angle γrel. [1 1 0] Sampling Period Ts: Ts = T1 + T2 + T0 V2 (13) Volt-Second Balancing: T2 ⋅ V2 Ts C D B E Figure 8 V ref ⋅ T s = V 1 ⋅ T 1 + V 2 ⋅ T 2 + V 0 ⋅ T 0 Vref A γrel F (14) [100] T1 ⋅ V1 Ts V1 Reference Vector Approximation Taking into account the scaling of the reference vector and expressing the complex numbers in polar coordinates, the following equations are valid for the PWM on-time of a space vector modulation: 3 ⋅ T s ⋅ V ref π T 1 = ------------------------------- sin --- – γ rel V DC 3 (15) 3 ⋅ T s ⋅ V ref T 2 = ------------------------------- sin ( γ rel ) V DC (16) T0 = Ts – T1 – T2 (17) The design of the switching sequence depends on the application requirements. Usually the number of switchings is minimized, in order to reduce switching losses to a minimum. The following figure shows a seven segment switching sequence: TPWM VU t VV t VW Figure 9 [000] [100] [ 110] [111] [110] [100] [000] T0/ 4 T1 /2 T2 /2 T0 /2 T2 /2 T1 /2 T0 /4 PWM Pattern of a Seven Segment Switching Sequence Application Note 8 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Theory of Sensorless Field Oriented Control The output voltage of each leg to neutral is shown in Figure 10. A B VU [100] Figure 10 C D VV [110] E F VW [010] [011] [001] [101] [100] Output Voltage of Space Vector Modulation The voltages VUV, VUW and VVW at the motor are sinusoidal. 2.3 Phase Current Measurement For many motor control schemes, the phase currents are required as input values. A cost efficient method requires only one shunt in the DClink. Two phase currents can be reconstructed from the DClink current (IDClink) during one PWM period (TPWM). The third phase current can be calculated by IU + IV + IW = 0, but is redundant for the control. T PWM VU VV t VW t IDClin a k T 0/4 Figure 11 b c IU I-W T1/2 T 2/2 d T0/2 e f I-W IU T 2/2 T 1/2 g t T 0/4 t Phase Current Measurement within the PWM Pattern In order to realize this method, the ADC trigger points must be adjusted according to the PWM pattern. Two different currents can be measured at PWM time T1 and T2. Depending on the actual sector, the measured currents have a different meaning. The following table shows these combinations and the calculation for phase current IA and IB. Sector A B C D E F T1 U V V W W U T2 -W -W -U -U -V -V IA = IU U (-W) - V -(-U) -(-U) (-V) - W U IB = IV (-W) - U V V (-U) - W -(-V) -(-V) Application Note 9 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Theory of Sensorless Field Oriented Control 2.3.1 Limitations of Phase Current Reconstruction When T1 or T2 equals 0, only one phase current can be reconstructed. To avoid this situation, the PWM-times T1 and T2 have to be limited to a minimum value. This causes a ripple in the phase-phase voltage and the phase current as well. A very fast ADC is required in order to maximize the performance of phase current reconstruction. The following figure shows the output voltage and phase voltage of a T1-T2-limited space vector modulation. 800 800 700 600 600 400 500 200 V_UN 400 V_UN - V_VN V_VN 0 V_WN 300 V_VN - V_WN 0 60 120 180 240 300 V_WN - V_UN -200 200 -400 100 -600 0 0 Figure 12 60 120 180 240 300 -800 Distortion in Output and Motor Voltage Although the output signal is slightly distorted, the most cost efficient method of phase current measuring is the reconstruction from the DClink current via a single shunt. A very fast ADC is required to optimize the system performance. A direct trigger from the PWM unit to the ADC reduces CPU load significantly. Application Note 10 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Theory of Sensorless Field Oriented Control 2.4 FOC Calculations FOC is a method to generate a three phase sinusoidal signal, which can easily be controlled in frequency and amplitude in order to minimize the current and therefore maximize the efficiency. The essential idea is the transform of three phase signals into two rotor-fix signals and vice versa. In the rotor-fix reference frame, the currents are stationary and easy to control. The inverse vector rotation causes the contolled voltages to rotate. 2.4.1 Stationary and Rotating Reference Frames Rotating reference frame Two phase reference frame Three phase 120° reference frame IV Iq Iβ Id ϕ IU Iα A B C Iq D E A F Iα B C D E A F IU Iβ B C IV D E F IW Id IW Figure 13 Stationary and Rotating Reference Frames The transform from the three phase system to the two phase system is called the Clarke transform. The one from Two phase system to the rotating system is called the Park transform. These transfroms are expressed in the following equations. Clarke Transform iα = iU (18) 1 i β = ------- ⋅ ( i U + 2i V ) 3 (19) iU + iV + iW = 0 (20) i d = i α cos ϕ + i β sin ϕ (21) i q = – i α sin ϕ + i β cos ϕ (22) Park Transform Application Note 11 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Theory of Sensorless Field Oriented Control Inverse Park Transform i α = i d cos ϕ – i q sin ϕ (23) i β = i d sin ϕ + i q cos ϕ (24) Summary Transformations IV • Iq • Iβ • • Id θ Iα Clarke transformation is used to remove the redundancy of the 3 phase system Park transform provides a rotating d-q-reference frame The currents Id and Iq are stationary and easy to control The inverse Park transform makes the controlled voltages rotating IU IW Figure 14 Summary of Transformations Application Note 12 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Theory of Sensorless Field Oriented Control 2.4.2 Sensorless FOC The costs for an encoder or other position sensor can be saved, when the exact position of the rotor is not required. The motor’s back EMF is utilized in order to calculate the rotation angle and rotor position. The back EMF is calculated in the flux estimator, which is based on the voltage model of the system in the two phase reference frame. A single shunt is enough to reconstruct the phase currents. 0 reference speed speed + PI-controller - ω Id + - Vd inverse Park transform PI-controller Iq PI-controller + - Vq ϕ speed calculation Figure 15 Vβ cartesian θ to |V| polar transform PWM-Unit U Modulator V W Two-level Voltage Source Inverter (VSI) with integrated deadtime control Flux estimator Id Iq Vα Park transform Iα Iβ Clarke transform Current Calculation ADC IDClink shunt Block Diagram of Sensorless Field Oriented Control Figure 15 shows the block diagram of the sensorless FOC algorithm. The flux estimator’s input signals are taken from the orthogonal two phase stator system with the index α and β. The output signal represents the rotor angle. The motor signals in the two phase stator system (α-β-system) are equivalent to the three phase system. As a result, an ideal two phase motor can be assumed in the α-β-system. Then there are only two equations to calculate. The following figure shows the voltage equations of the motor in the α-β-system. Flux of stator ψs: β ω S N ϕ i sα Rs α (25) ψ sβ = L ⋅ i sβ + ψ pβ = L ⋅ i sβ + ψ p sin ( ϕ ) (26) Stator Voltage Equation: Ls v sα = R ⋅ i sα + dψ sα di sα dϕ = R ⋅ i sα + L ⋅ – ψ p sin ( ϕ ) dt dt dt (27) v sβ = R ⋅ i sβ + dψ sβ di sβ dϕ = R ⋅ i sβ + L ⋅ + ψ p cos ( ϕ ) dt dt dt (28) -ψp ω sin(ϕ) vsα isβ ψ sα = L ⋅ i sα + ψ pα = L ⋅ i sα + ψ p cos ( ϕ ) Rs Ls -ψp ω cos(ϕ ) vsβ Figure 16 Voltage Equations of Ideal 2-phase Motor The flux of the stator (Equation (25), Equation (26)) contain the mutual inductance with the permanent magnet ψ p . L ⋅ i s and the flux of the rotor The stator voltage equations (Equation (27), Equation (28)) contains the resistance of the coil derivative of the flux of the stator (Faraday’s Law). R ⋅ i s and the Application Note V 1.0, 2010-09 13 AP16180 XC2000 Sensorless Fieldoriented Control Theory of Sensorless Field Oriented Control Integrating the voltage equations, we calculate the stator flux as follows: ψ sα = ∫ ( vsα – R ⋅ isα ) dt (29) ψ sβ = ∫ ( vsβ – R ⋅ isβ ) dt (30) The flux of the rotor and hereby the orientation (angle ϕ) of the permanent magnet of the rotor is calculated by insertion of Equation (29) in Equation (25) and Equation (30) in Equation (26). ψ pα = ψ sα – L ⋅ i sα = ∫ ( vsα – R ⋅ isα ) dt – L ⋅ isα (31) ψ pβ = ψ sβ – L ⋅ i sβ = ∫ ( vsβ – R ⋅ isβ ) dt – L ⋅ isβ (32) ψ pβ ϕ = atan --------- ψ pα (33) Finally the position of the rotor can be calculated by knowing the resistance R and inductance L of the motor. The stator voltage vs is derived from the algorithm, and the current is needs to be measured in real-time. Application Note 14 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N 3 Implementation of a Sensorless FOC using the XC2236N Field Oriented Control or vector control is a math technique for controlling brushless dc and ac induction motors that reduces motor size, cost and power consumption and is a cousin of flux vector control. This Chapter describes the implementation of a sensorless Field Oriented Control using the Infineon XC2236N microcontroller. The XC2236N microcontroller is a new 64-pin device, part of the XC2000 family. Based on the enhanced C166S V2 architecture, it outperforms existing 16-bit solutions. The 3 PWM units, several timer and two very fast and powerful ADC’s make the XC2236N a perfect fit for a variety of motor control applications. PSRAM 16 KB DPRAM 2KB OCDS Debug Support DSRAM 16KB SCU: Voltage, Reset, EBC PMU MAC DMU Flash 64 KB XBUS Control External Bus Control CPU MPU Flash 256 KB C 166 SV2 - Core XTAL Osc / PLL Clock Generation RTC WDT Interrupt & PEC MCHK Interrupt Bus Peripheral Data Bus LX BUS 8/10 – Bit 2 Channels GPT CC 60 CC 61 T7 T2 T12 T12 T8 T3 T13 T13 USIC 0 64 entry buffer RS232, SPI, LIN, I²C, I²S, RS232, SPI, LIN, I²C, I²S, Channel 0 T4 USIC 1 64 entry buffer T5 T6 Channel 1 8/10 – Bit 7 Channels CC 2 Channel 1 ADC 1 Channel 0 ADC 0 MULTI CAN 1 Channels GPIO Ports Figure 17 Block Diagram XC2236N This application note makes reference to Infineon's FOC Drive Application Kit (ordering code: KIT_AK_TLE71184_V1). This kit comes with the following hardware: • • • • • • DriveCard XC886 DriveCard XC2236N Low Voltage Inverter TLE 7184F (12V...24V, 20A) PMSM motor (15W) DriveMonitor USB stick Power supply (12V) Figure 18 FOC Drive Application Kit Application Note 15 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N The sections which follow describe the FOC implementation on the 16-bit device XC2236N. The project setup is available for the Tasking Vx Tool chain.The project is DAvE compliant; i.e. the peripheral settings can be changed or added using DAvE code generator and recompiled afterwards. A MicroSoft Excel sheet can be used for scaling and motor parameter adaptation. The Excel sheet generates the contents for a header file. The DriveMonitor is used for real-time monitoring of those application variables that are of interest. The DriveMonitor also offers a control interface to the application. The CAN bus is used for exchanging of data. Note: The descriptions in the sections which follow are intended for the advanced user; i.e. some basic knowledge of the Infineon tool-chain is a prerequisite. Several application notes are available to aid understanding (see Chapter 6), and 'hands-on' training is also offered. Less advanced users are recommended to begin with the DaveDrive auto-code generator. Application Note 16 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N 3.1 System Overview The Field Oriented Control Application Software uses the Drive Card XC2236N. LV inverter Drive Card GPT12 T6 CAPCOM2 of T7 of of CCU60 of of pm pm T12PR t M0 Ramp t Scheduler + TPWM T12 T7PR T6PR Inverter CC60SR HS Driver CC61SR CC62SR t T5 of of of of of LS Driver of T13 T5PR pm pm T13PR t CAN Oscilloscope t XC2236N MultiCAN ADC0 ResReg0 CH8 Node0 Rshunt *G MO0 ResReg1 MO1 MO2 MO3 MO4 CH15: VDC ResReg7 CH13: POT ResReg6 System Block 0 + ymax y ymin + - x ymax KP *64 ymin + ymax y Vq D B E 0] HS Driver S A [100] F CC61SR ~3 phase motor CC62SR N t T13 LS Driver C pm pm T13PR svm.Amplitude t foc.Vq y 1 Ts + - Speed Calculation x = 1 T Flux Estimation i R + v n + - 0 foc.Fluxalpha x x y arctan x K = Z1/Z2 T = 1/Z2 y foc.IntegratorA status. control foc.FluxAngle i x Startup control R ≥ threshold + v ⇒ 0 control. ControlSwitch + K Ts 1 T 1 foc.Angle K⋅L T PT1 Speed 1 Carthesian to Polar Transform t foc.Angle foc.AngleStore control.Filter SpeedUser t n Slew = t control.ReferenceSpeedT0 control.SpeedRampTime control.ReferenceSpeedUser S N ymax 0 foc.Vbeta 0 PT1 Speed Ramp |V V 1 ymin control.Iq control. ActualSpeed C [011] ] control.Speed 1 sTI :1 [: s4] 1 [10 *64 control. ReferenceIq + pm CC60SR :4 [: s3] N KP PI ymin pm S x ymax Inverter TPWM T12PR foc.Vd S + - 1 sTI svm.Angle N control. ReferenceSpeed foc.Valpha CCU6E T12 0 control.Id PI Modulator N 1 ymin *64 Carthesian to Polar Transform V [00 1] KP y Vd S + ymax S ymin [11 Inverse Park Transform ymax 1 sTI 0] + - x [01 PI control. ReferenceId N Figure 19 DELTA_ANGLE_START foc.AngleSpeed K⋅L T PT1 + - + K Ts y foc.Fluxbeta 1 T V/f control x + y2 2 y |V| foc.FluxAmplitude K = Z1/Z2 T = 1/Z2 foc.IntegratorB * slew * 256 + offset gi_V_q_vf_slew ??? gi_V_q_vf_offset ?? Id Park Transform foc.Id I foc.Ialpha Clarke Transform Iα = 12 ⋅ I phaseA :1 Iq foc.Iq [: s2] I Iβ = 1 2 3 *16 [* s1] ⋅ (2 I phaseB + I phaseA ) IphaseA svm.IphaseA Current calc. RESULT0 IphaseB [: s0] ADC0 CH8 :4 *G Rshunt RESULT1 svm.IphaseB foc.Ibeta handled in the ADC Interrupts (ADC.c) Figure 20 RESULT6 CH15: VDC RESULT7 CH13: POT XC2000 Sensorless FOC Block Diagram Application Note 17 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N 3.2 Software/Hardware Components The implemetation of the FOC is interrupt driven. Most of all calculations are realized in the interrupt routines of the CAPCOM6 and the ADC0. ADC0: – – – – Initialization ADC result register control current calculation and phase current extraction clark transformation CAPCOM2: – Initialization – Bootstrap for TLE 7184F – Ramp-up time V/f for motor CAPCOM6: – – – – – – – – Initialization flux estimation park transformation speed calculation and speed control current control inverse park transformation cartesian to polar transformation space vector modulation GPT12: – Initialization – Generation of time base for oscilloscope data, scheduler CAN: – Interface for motor communication The modulator and the DSP routines for the FOC routines are optimized for the MAC unit. Modulator.c: – Space Vector Modulation Subroutines_FOC.c, Subroutines_FOC.h: – – – – Several DSP routines PI/PT1 routines FLUX estimation (Inverse) Clarke/Park transformation Scheduler.c – Scheduler 3.2.1 Scheduler The program flow of the target microcontroller is an embedded realtime code which runs in several interrupt service routines. There is GPT Timer 6 providing a system tick of 1ms which calls a scheduler. The scheduler statemachine controls the application and reacts on host commands. The Timer 5 of the GPT module send the Oscilloscope data every 0.5 millisecond via an interrupt. One message object is used to send the complete data. The structure is shown in Chapter 4.1.9. The Timer 5 interrupt uses the lowest priority in the system. The transfer rate of the data can be adapted to the application needs. Application Note 18 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N The GPT Timer 6 is configured as a Timer and generates a interrupt every millisecond, which executes the scheduler. The scheduler can be divided into a CAN handler and a statemachine part which handles the whole FOC application Software. For the FOC implementation a statemachines for Motor 0 is integrated. The scheduler handles the CAN commands and switches or reset's Statemachine states. Some Statemachine states are triggered from the CAN handler part of the Scheduler, while some are triggered/switched by other events or mechanisms. Figure 21 show the structure of the scheduler. The Figure 22 show the Statemachine for a single Motor application. After handling a new CAN command, information is sent to the drive monitor, such as the motor states and some control values such as Vdc, the temperature on the inverter. Scheduler Start no New Command? yes Handle Command Handle State M0 Send parameter Scheduler End Figure 21 Scheduler Sensorless FOC 3.2.2 Statemachine The FOC Software handles 8 different states for the Motor in a seperate global 16 bit word (STATE_M0). The dedicated states are listed for Motor 0 in the register view below. STATE_M0 Short Description Reset value: 0001H 15 14 13 12 11 10 9 8 7 6 - - - - - - - - - - - - - - - - - - - - 5 4 3 2 1 0 M0 States - rw rw rw rw rw The bits of the variable are described in a table that follows. Application Note 19 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N Field Bits Type Description M0 States [0:3] rw Statemachine States 0001 STATEIDLE_M0(Default) 0010 STATESTARTUP_M0 0011 STATESTOP_M0 0100 STATEFOC_M0 0101 STATERAMPDN_M0 0101 STATEEMCY_M0 0111 STATEBOOTST_M0 1000 STATEPOTI_M0 ... ... Note: Some states are triggered by the Drive Monitor, while other states are entered automatically and can not be influenced by the Communication Software. Power up ÆMain init Poti: Waits for a Poti value < 10 before start the motor POTI Off On closed_loop Trap CPU Trap EMERGENCYSTOP: MotorStop(); IDLE EMCY CTRAP: Off On closed_loop Trap low level at pin CTRAP Off On closed _loop Trap Start BOOTST Off On closed_loop Trap Stop Bootstrap: Switch on low sides wait n loops Power up STOP: MotorStop(); disable T12_INT disable TRAP_INT STOP STARTUP Off On closed_ loop Trap Stop Off On closed_loop Trap STARTUP: enable T12_INT MotorStart(); enable TRAP_INT ∆ϕ > threshold reference _speed < threshold RAMPDOWN: reference_speed_user = threshold; Stop Stop RAMPDN FOC Off On closed_ loop Trap Ramp Down Off On closed_loop Trap S chedulerS tateMachine_2009-04-09.emf Figure 22 Statemachine for Single Motor FOC On power-up the Statemachine normally enters the IDLE state. In IDLE state the Motor is stopped by Software and the CCU6 interrupts are disabled. To start the Motor, the BOOTST state is entered. BOOTST can also be entered directly after power-up, instead of IDLE. Whether IDLE or BOOTST mode is entered on power-up is defined by the DEFAULT_STATE setting in the define.h file. #define DEFAULT_STATE STATEBOOTST_M0 In the Bootstrap state the low side MOASFETs will be switched on for the dedicated number of the ramp-up timer interrupts. Application Note 20 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N #define BOOTSTRAP_M0 2 After this the STARTUP state is entered, which means the Motor will start to ramp-up. The FOC state is entered after a selected speed of the Motor when the sensor less FOC algorithm starts to handle the Motor. A CTRAP can cause an Emergency Stop as well a CPU TRAP. For more information about the Emergency handling refer to Chapter 3.2.6. 3.2.3 IDLE State IDLE is the default state entered on system power-up. In this state the CPU waits for new commands and for a trigger to start the motor. Status flags will be reset and the values for the CAPCOM2 ramp timer 7 can be configured. To change the timer value, DAvE generated functions are used. case STATEIDLE_M0: status0.on = 0; status0.control = 0; status0.off = 1; CC2_vStopTmr(CC2_TIMER_7); CC2_vLoadTmr(CC2_TIMER_7,control0.SpeedRampSlew); CC2_T7REL = control0.SpeedRampSlew; CC2_vStartTmr(CC2_TIMER_7); break; 3.2.4 STOP State The STOP state can be entered with a command from the DriveMonitor, or after the ramp-down state is finished. The STOP function disables the ENABLE signal for the driver IC, and also sets the status flags and FOC variables to their defaults. The CAPCOM60 Timer 12 is stopped and the interrupt nodes for Timer 12 and the Emergency interrup are disabled. 3.2.5 Ramp-down State The Ramp-down state can be entered by a command direct from the DriveMonitor. The user reference speed is set to the REFSPEED_STARTUP_M0. Once the reference speed matches the user reference speed, the state machine automatically enters the STOP state. The following shows a code extract from the scheduler function: case STATERAMPDN_M0: //This ramps down the Motor 0 -> the switch to idle will be done on the CCU2 T7 interrupt status0.on = 0; control0.ReferenceSpeedUser = REFSPEED_STARTUP_M0; break; Application Note 21 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N 3.2.6 Emergency Stop State The Emergency State can be entered from two different event triggers: – CCU60/CTRAP - this switches off the power devices if the trap input becomes active. – CPU TRAPS - Trap functions are activated in response to special conditions that occur during the execution of instructions. Motor enable = OFF Emergency STOP CPU TRAP Figure 23 CCU60 CTRAP Emergency Stop There are nine hardware trap functions for the XC2236N divided into 2 classes. Class A traps are: – – – – System Request 0 (SR0) Stack Overflow Stack Underflow trap Software Break. The second Class B traps are: – – – – – System Request 1 (SR1) Undefined Opcode Memory Access Error Protection Fault Illegal Word Operand Access. All this TRAP call the same Emergency_Stop_M0() function. An Emergency State can only be left with a STOP command from the Drive Monitor. 3.3 CAPCOM6 The PWM is generated with the CCU60 timer unit. Both timers T12 and T13 are used. T12 generates the signals for the Space Vector Modulation (SVM). T13 generates the trigger events for the ADC0. T13 runs in single shot mode and starts automatically on one defined compare match of one of the 3 compare channels. The generated trigger starts the conversion of the ADC0 channel which generates an interrupt after the channel is converted. Details of the ADC0 handling can be found in Chapter 3.4. The passive level selection of the CCU60 compare output signals fits to the Infineon system IC TLE7184F, see Chapter 3.7. To avoid spikes and dangerous transitions at startup the CCU60 has a special feature which is used for the initialization and for the Start/Stop/Emergency states. Therefore the CCU60’s trap state is forced by software. This is done at the very beginning of CC6_vInit() by setting the flag TRPF (note: DAvE does not set this flag). By this it is ensured that the output signals always show the defined passive level during initialization until the flag TRPF is cleared. There are two application specific constants which have to be defined before compilation in defines.h. They will be initialized accordingly: Application Note 22 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N T12PERIODE_M0 DEADTIME_M0 The T12 period needs to be setup according to the PWM frequency. The deadtime counter needs to be setup according to the Hardware setup. DAvE settings will be overwritten in this instance. The FOC algorithm can be explained by Figure 20. The shown building blocks are exactly implemented, mainly in the file Subroutines_FOC.c and Subroutines_FOC.h for inline functions. The FOC calculation is divided into two parts. The first part is located in the ADC0 Result event interrupt and executes the following calculations: – ADC result register control – current calculation and phase current extraction – clark transformation The second, larger part is located in the CCU6 Timer 12 period match of the Interrupt Service Routine, and executes the following calculations: – – – – – – – flux estimation park transformation speed calculation and speed control current control inverse park transformation cartesian to polar transformation space vector modulation The Timer 12 one match of the Interrupt Service triggers the shadow transfer for the compare channels. 3.4 ADC The current implementation uses several channels of the ADC0. Nevertheless a customer specific setup of the free and used ADC channels can be easily created within the DAvE project. CAPCOM60 Motor 0 ADC0 ResReg0 CH8 *G Rshunt ResReg1 ResReg7 ResReg6 Figure 24 CH15: VDC CH13: POT ADC0 Structure for Single Motor FOC The sensorless Field Oriented Control works with a single Shunt measurement. It is possible to economize one current sensor when the current measurement is not performed in the phases but in the dc-link. To effect this phase current acquisition through the dc link current it is necessary to know the actual switching pattern. In this way, during one PWM, two times, two different phase currents can be measured through a dc-link current measurement. The third phase current can be calculated by the equation iU+iV+iW=0. (see Chapter 2.3 for details). In order to get a maximum time between the current conversions with the ADC, the measurement will be started on the edge of the phase with the middle “on time” (Figure 25). Application Note 23 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N TPWM T12 T12PR CC60SR CC61SR CC62SR T13 hardware start T13PM hardware start T13PM T13PR IDClink Event (ADC0_INT0): Event (ADC0_INT1): Result Event 0 Result Event 1 Assign Result Register for DC Link channel T12 count down -> Result Register 1 selected Calculate new T 13 values T13 Shadow transfer enable Assign Result Register for DC Link channel Result Register 0 selected Figure 25 ADC Measurement 3.5 CAPCOM2 Calculate new T 13 values T13 Shadow transfer enable Calculate currents Ialpha and Ibeta Calculate currents Id and Iq The CAPCOM2 Timer 7 is base for all ramp-up and ramp-down functions of the sensorless FOC software. The speed ramp is dependent on three Excel parameters in the define.h file. REF_RAMPUP_T7_M0 T7_PRESCALER RAMP_STEP_M0 The REF_RAMPUP_T7_M0 defines the Timer ticks and T7_PRESCALER selects a pre scaler for Timer 7. The Ramp Step is also defined. This influences the slope of the ramp behaviour. The Timer 7 interrupt handles the following functions: – – – – – Bootstrapping time Ramp-up in V/f Ramp-up in closed loop FOC Ramp in case of user reference speed changes during run time Ramp-down in closed loop FOC Application Note 24 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N 3.6 Misc 3.6.1 VDC and Poti VDC and the Poti are connected to ADC0 CH13 and ADC0 CH15. Both channels will be converted with the parallel source which is basically a channel scan. The conversion request tigger is set in software in the GPT Timer 6 interrupt. Both results are stored into global variables. If the #define SPEED_POTI is set in the defines.h file, the poti on the XC2236N Drive Card will be used to control the speed of the Motor. The control function is located in the scheduler. 3.6.2 Interrupt Level The XC2236N provides 96 separate interrupt nodes assignable to 16 priority levels, with 8 sub-levels (group priority) on each level. The used interrupt level in this project are selected carefully. With the help of DAvE these levels can be adapted to application needs in case new peripherals like a USIC channel is added into the project. Figure 26 Interrupt Setup 3.6.3 Variable Definition and Administration The variables used for the FOC algorithm and control of the whole software are separated into 4 structs located in the Controls_FOC.h file. These structs are: – – – – tSVM svm0; tFOC foc0; tStatus status0; tControl control0; Each struct has associated variables. These structs are preloaded in the Main.c file variable declaration with the define values coming from the define.h file. These variables can be changed and monitored as required, via the DriveMonitor. 3.6.4 DAvE Support The project is based on DAvE with the DIP file for XC22xxN_Series V0.2. Setting changes can be made there, such as the GPT timer values to change the scheduler frequency for example, as well as adding new peripherals such as a USIC for example. Application Note 25 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N 3.7 System IC TLE7184F The TLE7184 is a system IC for Brushless Motor Control. It incorporates a voltage supply for a µC, a bridge driver for a B6 configuration, an application typical PWM interface and some other smaller features. Target is to reduce the number of discrete components in typical BLDC automotive applications and give enough flexibility for custom specific adaptations. The TLE7184F can be reset by the enable pin RGS. If the RGS pin is pulled to low for a specified minimum time (min. 3µs / max < 20µs) the error registers are cleared. If the error is still existing when the RGS pin is pulled to low, no reset will be performed and the ERR pin stays low. Figure 27 Enable / Disable Timing A MOSFET is a voltage controlled device which, in theory, will not have any gate current. This makes it possible to utilize the charge inside the capacitor for control purposes. However, eventually the capacitor will lose its charge (due to parasitic gate current), so this scheme is only used where there is a steady pulse present. This is because the pulsing action allows for the capacitor to discharge (at least partially if not completely). Most control schemes that use a bootstrap capacitor force the high side driver (N-MOSFET) off for a minimum time to allow for the capacitor to refill. This means that the duty cycle will always need to be less than 100% to accommodate for the parasitic discharge unless the leakage is accommodated for in another manner. The TLE184F provides a bootstrap based supply for its high side output stages. The benefit of this principle is a fast switching off the high side switches - supporting active freewheeling in high side. The bootstrap capacitors are charged by switching on the external low side MOSFETs connecting the bootstrap capacitor to GND. Under this condition the bootstrap capacitor will be charged from the VREG capacitor. If the low side MOSFET is switched off and the high side MOSFET is switched on, the bootstrap capacitor will float together with the SHx voltage to the supply voltage of the bridge. Under this condition the supply current of the high side output stage will discharge the bootstrap capacitor. This current is specified. The size of the capacitor together with this current will determine how long the high side MOSFET can be kept on without recharging the bootstrap capacitor. When all external MOSFETs are switched off, the SHx voltage can be undefined. Under this condition, the bootstrap capacitors can be discharged, dependent on the SHx voltage. Application Note 26 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N 3.8 Application States The startup mechanism to turn the motor can be divided into two parts. First the Motor will start to turn by a V/f to a dedicated user defined speed. From this point on the Field Oriented Control will handle the Motor. 3.8.1 Motor Ramp-up Motor rpm Startup control REFSPEEDUSER_ STARTUP_M0 ∆ϕ ≥ threshold ϕ + ∆ϕ ⇒ ϕ n Threshold ANGLESPEED_THRE SHOLD_M0 SpeedT 0 status . 1 control 0 ∆ϕ = t t foc.AngleSpeed foc.AngleSpeedT0 foc.AngleSpeedThreshold Bootstrap Figure 28 V/f Time in CCU2 T7 overruns FOC Motor Ramp-Up A #define in the define.h file is used to switch selection between the V/f control and FOC. #define CONTROL_SWITCH_M0 1 // Motor switches to FOC mode If this control switch is set to 0 the motor ramps-up to the angle speed threshold in the V/f control. The motor will run with that speed without switching to the FOC algorithm. This method can be use to check the calculated angle of the motor with the angle used in the V/f control. #define CONTROL_SWITCH_M0 3.8.2 0 // Motor stays in V/f control mode Running state After the motor ramps up to the defined threshold speed, the user can change the User reference speed with the DriveMonitor. In case the #define SPEED_POTI is active in the define.h file, the Poti of the DriveCard is used to change the speed of the Motor. 3.8.3 Motor RAMP-down After the scheduler receives the command for ramp-down (Chapter 3.2.5) , the reference speed will be rampeddown to the REFSPEED_STARTUP_M0. Once the speed ramp-down is complete, the scheduler state is automatically changed to the STOP state. The following shows a code extract from the CAMCOM2 Timer 7 interrupt function: //******************************************************************************** // controlling the speed of the Motor 0 if switched to control mode //******************************************************************************** if (STATE_M0 == STATERAMPDN_M0) { if(control0.ReferenceSpeedUser > control0.ReferenceSpeed) control0.ReferenceSpeed += RAMP_STEP_M0; if(control0.ReferenceSpeedUser < control0.ReferenceSpeed) control0.ReferenceSpeed -= RAMP_STEP_M0; if(control0.ReferenceSpeedUser == control0.ReferenceSpeed) { STATE_M0 = STATESTOP_M0; } } Application Note 27 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Implementation of a Sensorless FOC using the XC2236N 3.9 CPU Load Figure 30 shows the cpu load of the complete application. Basically the cpu load is generated by the interrupt routines of CAPCOM6 and ADC0. The cpu load is represented by the channel 3. The observer window starts with the timer 12 period match (T12PM) Interrupt Interrupt Interrupt CCU6 CCU6 ADC CPU Load T12PM Interrupt ADC T12OM Output CC60 Output CC61 Output CC62 Figure 29 CPU Load Application Note 28 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Communication Interface 4 Communication Interface Communication is via the Drive Monitor Software for the PC and the Drive Monitor USB Stick. Download to the XC2236N is via the JTAG connection. Motor communication, such as Start and Stop commands, is via MultiCAN. The XC2236N uses the MultiCAN Node 0 running at 500kBaud, together with several Message objects, for this communication. For more information about the Drive Monitor please refer to the AppNote: Drive Monitor, Hardware Description (ap0807120_DriveMonitor.pdf).[1] 4.1 MultiCAN Interface In the current Implementation, five CAN Message objects are used. Message Object 10 is configured as the receive object, forwarding commands from the Drive Monitor Software via a CAN receive interrupt, to the Scheduler. CAN message objects MO1 through to MO4 are used for data transfer from the XC2236N to the Drive Monitor Software. 4.1.1 Program Flow XC2236N The CAN controller is configured to three interrupt vectors for receive, transmit and error handling. The CAN Message Objects have following IDs: – – – – – ID5 - receive object - MO 10: SET/GET command and Buttons ID55- receive object - MO 2; unused ID7 - transmit object - MO1; slow data for status flags and display field ID77- transmit object - MO 3; fast data for oscilloscope and progress bar ID57- transmit object - MO 4; responds to GET command RESET CAN – REC ID 5 Initialize Application copy message to buffers CANRxdBuf0 MAIN Scheduler send CAN messages reti CAN– TRX ID 7 / ID 77 / ID57 clear message pending flags of sent objects reti GPT T6 every 1ms CTRAP interrupt Scheduler ADC Poti VDC set emergency state switch states upon command exec. ret Figure 30 ADC GPT T6 Handels ADC results Send Oszi Data reti reti CCU60 T12 interrupt CCU2 T7 interrupt CC6 Shadow Transfers Speed Ramp Speed Control FOC_Calculation reti reti reti reti Program Flow Application Note 29 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Communication Interface 4.1.2 Command Structure The command structure is as per the document ap0807120_DriveMonitor.pdf.[1] D0 D1 D2 D3 D4 D5 D6 D7 CAN ID 0 0 0 CMD 5 commands from DriveMonitor to target adrL adrH valL valH 4.1.3 Receiving a CAN Message and Command Execution On receipt of a CAN message object (M0 10 with ID5) the receive interrupt is vectorized. The interrupt service routine scopes the received data into a global array named CANRxdBuf0. The following shows a code extract of the CAN Receive interrupt service routine: // The CAN controller has stored a new message into this object. // USER CODE BEGIN (SRN0_OBJ10,4) CANRxdBuf0[0]= CAN_MODATA10LL; CANRxdBuf0[1]= CAN_MODATA10LH; CANRxdBuf0[2]= CAN_MODATA10HL; CANRxdBuf0[3]= CAN_MODATA10HH; // USER CODE END At every system timer tick the scheduler statemachine is executed. If a new command is received, the corresponding command is executed and the CANRxdBuf0 is cleared. The CAN receive interrupt and the GPT Timer 6 for scheduler use the same interrupt level. This mechanism ensures that an incoming command has to be served first before a new command is accepted. 4.1.4 Transmitting a CAN Message There are three transmit message objects configured for sending data from the target to the host. The transmit messages have to be initialized. The transmit buffers CANTrxBuf0/1 are used to load the data to the message objects. The load, release and transmit request functions are generated functions from DAvE. The following show a example code of the transmit function for message object 3: _inline void CAN_Transmit_MO3(void) { // MO3 is shown in Oscilloscope CAN_vLoadData(3, (ubyte*) CANTrxBuf1 ); CAN_vReleaseObj(3); CAN_vTransmit(3); } 4.1.5 Command SET With the SET command any variable of the FOC structs can be updated. Therefore it is necessary to have the address information of the respective variables. Address and data information are read from the CANRxdBuf0 and the contents of the address is written with the new value. The following shows a code extract of the scheduler function: Application Note 30 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Communication Interface case CMDSET: // // // // D0 D1 D2 byte # 0 1 2 3 4 5 6 7 CMD byte adrL adrH valL valH xxxx xxxx cmdL cmdH CMD int adr val x CMDSET int # 0 1 2 3 adr = (unsigned int*) CANRxdBuf0[0]; value = CANRxdBuf0[1]; *adr = value; // dont change state break; D3 D4 D5 D6 D7 CAN ID 0 0 cmdL cmdH 5 commands from DriveMonitor to target adrL adrH valL 4.1.6 Command GET valH With the GET command the host can read the contents of any variable. The host has to send the address information first before the target responds with the data on transmit message object MO 4. The following shows a code extract of the scheduler function: case CMDGET: // // // // byte # 0 1 2 3 4 5 6 7 CMD byte adrL adrH xxxx xxxx xxxx xxxx cmdL cmdH CMD int adr xxx xxx CMDGET int # 0 1 2 3 adr = (unsigned int*) CANRxdBuf0[0]; // Transmit MO 4 on request tmp[0] = (unsigned int) adr; tmp[1] = *adr; CAN_vLoadData(4, (ubyte*) tmp ); CAN_vReleaseObj(4); CAN_vTransmit(4); // dont change state break; D0 D1 D2 D3 D4 D5 D6 D7 CAN ID 0 0 0 cmdL cmdH 5 from DriveMonitor to target adrL adrH Application Note 0 31 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Communication Interface 4.1.7 Button Start, Stop, Ramp Down On pressing the Start, Stop or Ramp Down buttons, the scheduler state variable is updated and will be entered. D0 D1 D2 D3 D4 D5 D6 D7 CAN ID 0 0 0 cmdL cmdH 5 from DriveMonitor to target 0 0 0 4.1.8 Scope Buttons Realtime monitoring of fast changing data is one of the key features of the DriveMonitor. Therefore the CAN message object MO 3 - ID 77 is sent with every GPT timer 5 tick to the host. With this message three 16bit values can be monitored on the three beams of the virtual scope. With the scope buttons the addresses of the three monitoring variables can be changed. The following shows a code extract of the scheduler function: case CMDSETBEAMS: //Button Values: SCOPEgreen | SCOPEpink | SCOPEyellow | CMDSETSCOPE: ScopePointer[0] = CANRxdBuf0[0]; ScopePointer[1] = CANRxdBuf0[1]; ScopePointer[2] = CANRxdBuf0[2]; break; 4.1.9 Oscilloscope and Progress Bar With every GPT Timer 5 over flow the data for the soft oscilloscope and the progress bar are sent to the host. These data have the highest transmit rate. The user has to ensure that the realtime conditions are met. This can be tuned with the GPT timer 5 overflow rate. The fast data use ID77 with MO 3. D0 D1 D2 D3 D4 D5 D6 D7 CAN ID pinkH yellowL yellowH 0 0 5 from DriveMonitor to target greenL greenH Application Note pinkL 32 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Communication Interface Figure 31 Drive Monitor Oscilloscope 4.1.10 Status Flags and Display Fields For slower changing data, it is sufficient to send the data over a greater number of timer ticks. Such data would be the status flags and display fields for example. The transmit rate is defined by a variable which counts a defined number of system timer ticks. The slow data use ID7 with MO 1. The following shows a code extract scheduler function: //send parameter via CAN if (++CANMO1Count == 50) { CANTrxBuf0[0] = (unsigned int)status0.off | ((unsigned int)(status0.on)<<1) | ((unsigned int)(status0.control)<<2) | ((unsigned int)(status0.ramp)<<3) | ((unsigned int)(status0.ctrap)<<4) ; CANTrxBuf0[1] = svm0.Amplitude; CANTrxBuf0[2] = control0.ActualSpeed; CANTrxBuf0[3] = ADC_VDC; //VDC CAN_Transmit_MO1(); CANMO1Count=0; } Application Note 33 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Configuration and Monitoring 5 Configuration and Monitoring 5.1 Excel Sheet and defines.h Parameterization of the application is done via the header file defines.h. An Excel sheet (see Figure 33) is used to generate this files contents. The algorithm itself is left untouched. The Excel sheet has two pages: the input page Input Parameter and the output page defines.h. The Input Parameters can be filled into the yellow marked fields. These are the most relevant parameters. The structure is as follows: • • • • • • • • Motor Parameter - this is the resistance and inductance of the motor windings. The input value refers to one phase, i.e. phase-to-neutral and not phase-to-phase. Startup Parameter - these are the values which are used in the startup block. Inverter Parameter - in case customized inverter is used, it can be adapted here. Current Measurement - in case the current amplification or the shunt is changed it has to be changed here. Speed and Current Controller - here the integral and proportional factor for the PI-controllers can be adjusted. Flux Integration Scaling - here the PT1 filter for the flux estimator can be adjusted. Speed Filter - here the PT1 filter for the speed filter can be adjusted Speed Ramp - here the speed ramp time can be adjusted. In case the Speed Ramp time in the startup parameters is not fast enough, the incremental steps can be increased. The parameters influence each other, e.g. a very low inductance value L will scale to a very low value L’ which is used for the flux estimator. In this case the input parameter K in the Flux Integrator Scaling should be increased. If the Excel sheet shows red marked cells the scaling paramaters have to be changed accordingly. XC2000 sensorless FOC Parameter Calculation v1.0.00 Motor Parameter R L Pole Pairs MAXON EC32-flat 1,715 ohm 935 µH 4 Startup Parameter Startup Speed T0 Startup Speed Threshold Startup V/f offset (f = 0) Startup V/f slew rate Reference Speed User Speed Ramp 0 1000 1 0,092307692 2000 5000 Inverter Parameter DC link voltage dead time switch delay (max) PWM frequency Bootstrap precharge time ENABLE pin logic level 12 1 0,7 15000 1,5 1 Scale Factors for Drive Monitor rpm rpm V V/Hz rpm rpm/s V µs µs Hz ms 1: high active -1: low active Autostart enable Use poti for speed 0 0 Current Measurement R_shunt R_IN R_feedback maximum Voltage at ADC 0,005 0,39 6,19 5 Speed PI Controller Ki Kp Current PI Controller scale Figure 32 ohm kOhm kOhm V Startup Startup V/f offset (f = 0) Startup V/f slew rate 0,000206 V 0,000014 V/Hz Speed speed 3,433228 rpm Voltages V(d,q) V(D,E) V(svm amplitude) 0,000206 V 0,000822 V 0,011871 V Currents I(d,q) I(D,E) I(u,v,w) 0,000452 A 0,000452 A 0,007235 A PI Controller Speed kp 0,001953 Speed ki 0,000031 Current kp Current ki 0,001953 0,000031 0,01 ( < 0,5 ) 10 ( < 64 ) (<= 0,1) (<= 0,1) Excel sheet input page Application Note 34 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Configuration and Monitoring After changing the Input Parameter, the contents of output page has to be copied to the file defines.h, the C-project has to be re-complied and downloaded to the target. The Excel file also creates the scaling factors for the DriveMonitor. For instance the speed scaling changes when the number of pole pairs changes. These values have to be adapted inside the DriveMonitor configuration (CAN control editor). 5.2 Drive Monitor The DriveMonitor is a hardware tool which bridges USB to CAN. With this it is possible to monitor some interesting data of the target on a host PC in real-time. For more information please refer to the DriveMonitor application note in [1]. 5.2.1 Configuration The configuration of the DriveMonitor setup can be found in the DriveMonitor application note in [1]. 5.2.2 Monitoring the Startup Behavior Different motors have different startup behavior. The starting up of a synchronous motor takes effort. The first revolutions have to be done in an open loop mode before the FOC algorithm can take over. There are some values which mainly influence the startup behaviour. These values can be found in the Excel sheet under Startup Parameter and will be discussed below. After setting the correct R and L values, compilation and downloading, the DriveMonitor can be started and used in Setting 1 | Startup. Figure 33 Drive Monitor Setting 1 | Startup After connecting to the target, the button Scope Start should be pressed and then the button Start. The motor should start turning and after a few seconds the Stop button can be pressed. The scope shows in this setting two interesting signals: • pink: • yellow: Angle from the Startup Control block which is the given angle following the V/f ramp depending on the slew rate FluxAngle from the Carthesian to Polar Transform block, which is the estimated (calculated) angle based on the current measurement. Application Note 35 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Configuration and Monitoring Example Fan: After a few revolutions the estimated angle (yellow) and the given angle (pink) are quite similar. The FOC takes over at the speed threshold point. DriveMonitor: Speed ref defines.h: AngleSpeedThreshold Figure 34 Startup Behaviour of a Fan before Optimization Example Fan: After optimization of Vf_offset and Vf_slew the startup behavior is much better (less ripples on the estimated angle). Figure 35 Startup Behaviour of a Fan after Optimization The point where the FOC takes over from the V/f control is of special interest. The V/f algorithm increases the speed continuously until the threshold value is reached (Excel: Startup Speed Threshold, defines.h: AngleSpeedThreshold). At this point the current and speed controllers cannot deliver the correct output as they start here. The algorithm can only prepare the controllers accordingly. Therefore the current controller’s integral part is preset with current amplitude (Vq) based on the V/f calculation otherwise the amplitude would drop immediately. This is accomplished in CC2.c Timer interrupt function by preloading control0.Iq.Yn: //***************************************************************************************** // ramp up to motor 0 //***************************************************************************************** if (STATE_M0 == STATESTARTUP_M0) { if( (control0.ReferenceSpeedUser>0?foc0.AngleSpeed:-foc0.AngleSpeed) < foc0.AngleSpeedThreshold ) foc0.AngleSpeed += (control0.ReferenceSpeedUser>0?RAMP_STEP_M0:-RAMP_STEP_M0); else { if(control0.ControlSwitch) { Application Note 36 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Configuration and Monitoring // preload parameters control0.Iq.Yn = ((long)foc0.Vq)<<16; // preload Iq-current controller integral value to last V/f-amplitude value //******************* status0.on = 0; status0.control = 1; svm0.SVMTMIN = SVMTMIN_M0; STATE_M0 = STATEFOC_M0; } } } The speed controller must adjust at runtime. Therefore it is advisable that the speed controller is started with an input step, i.e. a difference between the ANGLESPEED_THRESHOLD_M0 and the REFSPEED_STARTUP_M0. In DriveMonitor the value Speed Ramp can be adjusted by Speed_ref, i.e. the user can play with this value. reference speed actual speed Output of speed controller: Iq_reference a) Figure 36 b) c) Switching point from V/f to FOC with different Speed_ref settings In Figure 37 different threshold conditions can be observed: a) REFSPEED_STARTUP_M0= ANGLESPEED_THRESHOLD_M0 b) REFSPEED_STARTUP_M0>ANGLESPEED_THRESHOLD_M0 c) REFSPEED_STARTUP_M0>>ANGLESPEED_THRESHOLD_M0. Application Note 37 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control Configuration and Monitoring 5.2.3 Monitoring the Runtime Behavior The Runtime behavior can be influenced by the PI parameter settings of the speed and controllers. Here the DriveMonitor offers the window Setting 2 | Control. The ki and kp parameters can be easily adjusted. For monitoring the Scope Speed or Scope I_uvq can be used. Figure 37 Drive Monitor Setting 2 | Control Pink: reference speed green: actual speed yellow: output of current regulator small Kp Application Note large Kp 38 V 1.0, 2010-09 AP16180 XC2000 Sensorless Fieldoriented Control References 6 References [1] Application note - AP0807120_DriveMonitor [2] Application note - AP0808810_XC878DriveCar [3] Application note - AP1617910_DriveCard_XC2236N [4] Application note - AP0805910_Sensorless_FOC [5] Application note - AP08090_XC878_Sensorless_FOC [6] Link to free toolchain program -- http://www.infineon.com/Freetools [7] Link to FOC Drive page - www.infineon.com/FOCDRIVE Note: Please check the Infineon website (www.infineon.com) for the latest Version of these documents. Application Note 39 V 1.0, 2010-09 w w w . i n f i n e o n . c o m Published by Infineon Technologies AG