AVR32723: Sensor Field Oriented Control for
Brushless DC motors with AT32UC3B0256
Features
• Standalone Space Vector Modulation library for AVR®32 UC3 microcontroller.
• Park and Clarke mathematical transformation library for AVR32 UC3
microcontroller.
• Theory of Field Oriented Control.
• PC application for real time motor remote control and display of regulated
variables.
32-bit
Microcontrollers
Application Note
1 Introduction
This application note delivers an implementation of Sensor Field Oriented Control
algorithm for brushless DC motor on Atmel® AVR32 UC3B microcontrollers.
This software includes standalone libraries for all mathematical transformations
required by the algorithm.
For more information about the AVR32 architecture, please refer to the appropriate
documents available from http://www.atmel.com/avr32.
2 Requirements
The software provided with this application note requires several components:
•
A computer running Microsoft® Windows® 2000/XP/Vista® or Linux®
•
AVR32Studio and the GNU toolchain (GCC) or IAR Embedded
Workbench® for AVR32 compiler.
•
A JTAGICE mkII or AVROne! debugger
Rev. 32126A-AVR32-06/09
3 Theory of Operation
3.1 Overview
As continuity in the energy efficiency process, the increase of capability of
microcontrollers allows to implement complex algorithm as Field Oriented Control
methodology which allows to:
•
Reduce power consumption (less power loss) of electrical motor driving.
•
Provide smoother and more accurate motor control than sinusoidal command
with hall feedback.
•
Optimize motor choice (torque): find the best alternative between dimension
and power.
But this algorithm requires more complex computation and requires more CPU
bandwidth than standard algorithms.
Moreover, this command strategy fits with some brushless DC motors with dynamical
load changes due to reduction of response time. It allows regulating torque and speed
at the same time.
3.2 Block Diagram
The following block diagram describes the principle of the algorithm. Indeed, it is
based on:
•
A vectorial command for 3-phases Brushless DC Motors.
•
A periodic current sampling of the 3 shunts located on these 3-phases.
•
2 encapsulated regulation loops: one for the current (torque and power loss)
and another for the speed.
Figure 3-1. Block Diagram
Field Oriented Control Block
Current
3-phases current
Regulation loop
(Ia,Ib,Ic)
Speed Target
Vectorial
Command
Speed
Regulation loop
Speed
and Position
2
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3.3 System Overview
As shown Figure 3-2, the 3-phases current are measured and one Hall Effect
feedback is used to compute field oriented control algorithm.
Figure 3-2. System Overview
PWM
3-phases Inverter
PWM_XH
PWM_XL
PWM_YH
3-phases
BLDC
AT32UC3B0256 (256K flash, 32 K RAM)
PWM_YL
PWM_ZH
Sensor
FieldOriented
Ccontrol
Process
PWM_ZL
Current
IA
IB
IC
Speed
Hall Effect A
USB-CDC
USB Task
PC
32126A-AVR32-06/09
The USB connection is used through a PC application for real time motor remote
control and display of regulated variables. This data monitor displays feedback control
remotely. This GUI provides:
- 3 graphs and 1 cursor display.
-
4 inputs control.
The purpose is to be able to connect to the application without disturbing the behavior
of the application. The application offers the following features:
1
4
-
Implements vector control of a Brushless DC motor.
-
Speed range from 400 rpm to 2000 rpm. 1
-
With a 100 µsec control loop, the CPU is used at 35% by the Sensor Field
Oriented Control Process at 42MHz.
-
Display in real time the current and speed measured.
-
Control of speed in real time.
See section 5.9 for the explanation of this limitation.
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4 Motor Control Theory
4.1 General Model.
The mathematical model in a constant domain linked to the stator is linked to
differential equation with constant coefficients defining the motor behavior.
Applying the Lenz-Faraday model, we have:
[Vabc]= R [Iabc]+ dtd [Φabc]
With:
⎡va ⎤
[Vabc ] = ⎢⎢vb ⎥⎥ ,
⎢⎣vc ⎥⎦
⎡ ia ⎤
⎡Φ a ⎤
⎥
⎢
[Iabc ] = ⎢ib ⎥ and [Φabc ] = ⎢⎢Φb ⎥⎥
⎢⎣ic ⎥⎦
⎢⎣Φc ⎥⎦
[
vb vc ]t are the statoric voltages, [ia ib ic ]t are
Φb Φc ]t are the global fields in the statoric solenoid.
R is the statoric resistance, va
[
the statoric current and Φa
[Φabc ] = [L][Iabc ] + [Φsf ]
We can write :
⎡ Ls
[Φ abc ] = ⎢⎢ M
⎢⎣ M
M
Ls
M
⎡
M ⎤ ⎡ i a ⎤ ⎢ Φ sf cos( θ )
⎢
2π
M ⎥⎥ ⎢⎢ i b ⎥⎥ + ⎢ Φ sf cos( θ −
3
Ls ⎥⎦ ⎢⎣ i c ⎥⎦ ⎢⎢
2π
Φ sf cos( θ +
3
⎣⎢
⎤
⎥
⎥
)⎥
⎥
)⎥
⎦⎥
Ls (constant) is the inductance in a statoric gyres.
M (constant) is the mutual inductance between the 2 statoric gyres
θ is the electrical position of the rotor (θ= θélec)
Фsf is the max value (constant) of the flux create by the permanents magnet through
the statoric gyres.
⎡
⎤
⎢
⎥
Φ
θ
sf
cos(
)
⎡ Ls M M ⎤ ⎡ia ⎤
⎡ia ⎤
⎡va ⎤
⎢
⎥
d
d
π
2
⎢vb ⎥ = R ⎢ib ⎥ + ⎢ M Ls M ⎥ ⎢ib ⎥ +
Φ
sf cos(θ −
)
⎢
⎥
⎥ ⎢ ⎥ dt
⎢ ⎥ dt ⎢
⎢ ⎥
3 ⎥
⎢
⎢⎣ M M Ls ⎥⎦ ⎢⎣ic ⎥⎦
⎢⎣ic ⎥⎦
⎢⎣vc ⎥⎦
⎢Φsf cos(θ + 2π )⎥
⎢⎣
3 ⎥⎦
In order to simplify the mathematical resolution of this system, some mathematical
transformations are used.
Using the Park P1(θ), the instantaneous power is kept and it allows to have a
mathematical expression of the torque still acceptable for the real motor.
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Using the Park inverse transformation, it is possible to return to the values space from
regulated values and generate commands.
4.1.1 Park Transformation (P1(θ)) and Clarke Transformation (inv P-1(θ)) 2.
The Park transformation is defined from the matrix P1(θ), it defines the link between
the real vectors Vabc , Iabc et Φabc , the new vectors V 0 dq , I 0 dq et Φ 0 dq .
[ ] [ ] [
P1(θ ) =
⎡
⎢
2 ⎢⎢
3⎢
⎢
⎢
⎣
1
2
1
2
1
2
]
[
][
] [
]
⎤
⎥
2π
2π ⎥⎥
cos(θ −
) − sin(θ −
)
3
3 ⎥
2π
2π ⎥
cos(θ −
) − sin(θ −
)
3
3 ⎥⎦
cos(θ )
− sin(θ )
Figure 4-1. Park Transformation
Vq
vb
Vd
va
[P1(θ)]
-1
θ
[xabc]=P1(θ)[X0dq]
va
V0
vc
With V0 =0V, I0 =0A and Φ0 =0Wb, the normalized Park transformation is the addition
the Concordia Transformation T32 and the rotating matrix p(θ) :
⎡+
⎢
⎢
1 ⎢
T 32 =
⎢−
3⎢
⎢
⎢−
⎣
2
2
2
2
2
0 ⎤
⎥
⎥
3⎥
+
⎥
2⎥
3⎥
−
⎥
2⎦
⎡cosθ − sinθ ⎤
p(θ ) = ⎢
⎥
⎣sinθ cosθ ⎦
Figure 4-2. 3D to 2D Transformation
xa
xb
xc
xα
t
32
T
Xd
P(-θ)
xβ
Xq
2
The Park and Clarke transformations are implemented as a software library
component in the software package associated with this application note. See also
section 5.
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4.2 Power Bridge Command.
The power bridge stage is here to power the BLDC motor with alternatives voltages
from a continuous source. This bridge allows modulating frequency and amplitude.
Figure 4-3. Power Bridge Stage
I
Ta
Tb
Tc
ia
a
a
E
b
ib
b
n
c
c
’
’
Ta
Tb
Ca C’a
m
Cb
ic
T’c
C’b
Cc
C’c
Figure II-1 Onduleur de tension triphasé.
Power Bridge Stage
The logical signals Ca, C’a, Cb, C’b, Cc and C’c are command signals for the power
bridge.
The output voltages are given from the ground ‘m’ of source generator and from the
virtual neutral point ‘n’ of BLDC motor.
⎡Ca ⎤
⎡Vam ⎤
⎢Vbm ⎥ = E ⎢Cb ⎥
⎢ ⎥
⎢ ⎥
⎢⎣Cc ⎥⎦
⎢⎣Vcm ⎥⎦
(II-1)
Vam = Van + Vnm
Vbm = Vbn + Vnm
Vcm = Vcn + Vnm
For an equilibrated load: Van + Vbn + Vcn = 0 V, so : Vnm
=
1
(Vam + Vbm + Vcm ) .
3
In that way, we have:
⎡Van ⎤
⎡ 2 − 1 − 1⎤ ⎡Vam ⎤
⎡ 2 − 1 − 1⎤ ⎡Ca ⎤
⎢Vbn ⎥ = 1 ⎢− 1 2 − 1⎥ ⎢Vbm ⎥ = E ⎢− 1 2 − 1⎥ ⎢Cb ⎥
⎢ ⎥ 3⎢
⎥⎢ ⎥ 3 ⎢
⎥⎢ ⎥
⎢⎣Vcn ⎥⎦
⎢⎣− 1 − 1 2 ⎥⎦ ⎢⎣Vcm ⎥⎦
⎢⎣− 1 − 1 2 ⎥⎦ ⎢⎣Cc ⎥⎦
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Or :
⎡ 2 − 1 − 1⎤
⎡Van ⎤
⎡Vα ⎤
1⎢
⎥
t
t ⎢
T 32 . ⎢− 1 2 − 1⎥ = T 32 . and ⎢ ⎥ = T 32 ⎢Vbn ⎥⎥
3
⎣Vβ ⎦
⎢⎣− 1 − 1 2 ⎥⎦
⎢⎣Vcn ⎥⎦
⎡Ca ⎤
⎡Vα ⎤
⎢ ⎥
t
t
We conclude so: ⎢ ⎥ = T 32 .E Cb , ( T 32 is the translation of T 32 )
⎢ ⎥
β
V
⎣ ⎦
⎢⎣Cc ⎥⎦
t
The following table gives the voltage values in the spaces ( α , β ) and (a, b, c).
Table 4-2. Voltage Values in the spaces ( α , β ) and (a, b, c)
Vector
Ca
Cb
Cc
Vα
Vβ
Van
Vbn
Vcn
V0
0
0
0
0
0
0
0
0
V1
1
0
0
1
0
2
-1
-1
1
V2
1
1
0
2
√3
2
1
1
-2
1
0
-1
2
-1
-2
1
1
V3
0
1
E
V4
V5
0
0
1
1
0
1
2
2
√3
2
3
-1
0
1
√3
2
-1
-1
2
2
1
E
3
V6
1
0
1
2
√3
2
1
-2
1
V7
1
1
1
0
0
0
0
0
We show that all vectors components (V α , V β ) are with modules 2 3 E and are
located in the regular hexagon.
Figure 4-4. Space Vector values in the regular hexagon.
(0, 1, 0)
Vβ
2
V3
(0, 1, 1)
V4
3
4
V5
3
(1, 1, 0)
V2
2
1V
(0, 0,
(1, 1,
5V
6
(0, 0, 1)
8
(1, 0, 0)
1
Vα
6
(1, 0, 1)
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4.2.1 Space Vector PWM. 3
The vectorial modulation uses directly the signal for the Concordia transformation. It
supposes that a regulation loop is ever implemented for the generation of V α and Vβ
components.
As stated below, at a instantaneous point, the power bridge is able to generate only 8
voltages (Vi, i = 0,…,7) in the space of transformation Concordia (V α , Vβ) with two
components equal to 0 and 6 with the module equal to E 2 3 and the angle
to (π 3) (i − 1) . Two successive vectors, called Vi and Vi+1 defined a sector i (Figure
4-4) with I from the interval [I, VI].
⎛Vα ⎞
Vi = ⎜⎜ ⎟⎟
⎝Vβ ⎠ i
⎡ ⎧π
⎫⎤
⎢cos⎨ 3 (i − 1)⎬⎥
2⎢ ⎩
2 ⎡⎧π
⎭⎥
⎫⎤ ⎡1 ⎤
=E
p ⎢⎨ (i − 1)⎬⎥ ⎢ ⎥
=E
3 ⎢ ⎧π
3 ⎣⎩ 3
⎭⎦ ⎣0 ⎦
⎫⎥
⎢sin ⎨ (i − 1)⎬ ⎥
⎭⎦
⎣ ⎩3
The power stage is only able to deliver voltages instantaneous voltages on a
sampling period T, we can write:
(Vαβ ) = δ i Vi + δ i + 1 Vi + 1
Where
δi
Vi and Vi+1 ;
3
δ i + 1 are the duration for relative values are the relatives voltages when
δ iVi and δ i + 1Vi + 1 are the projection of vector (V αβ ).
and
The Space Vector Modulation is implemented as a software library component in the
software package associated with this application note. See also section 5.
32126A-AVR32-06/09
Figure 4-5. Sector Determination Algorithm.
V α and Vβ
Yes
No
Vβ ≥ 0
i=1 or 2 or 3
i=4 or 5 or 6
Yes
No
Yes
Vα ≤ 0
Vα ≥ 0
i=1 or 2
i=2 or 3
No
Yes
No
i=5 or 6
Yes
Vβ-√3 Vα≤ 0
Vβ+√3 Vα≤ 0
No
n
i=4 or 5
No
Yes
Yes
Vβ+√3 Vα≤ 0
No
Vβ-√3 Vα≤ 0
Yes
i=1
i=2
i=3
i=2
i=5
i=6
i=5
i=4
In all cases, it is needed to determined sector number « i » where is located the
vector Vi . To reduce time execution computing δ i et δ i + 1 , we have used this
algorithm.
In that way, δ i et
δ i +1
are calculated directly from V α and V β :
⎡Vα ⎤
⎡Vα ⎤
⎡Vα ⎤
⎢Vβ ⎥ = δ i ⎢Vβ ⎥ + δ i + 1⎢Vβ ⎥
⎣ ⎦ i+1
⎣ ⎦i
⎣ ⎦
And so
⎡Vα ⎤
Π ⎡1 ⎤ ⎫
2 ⎧ ⎛π
⎞ ⎡1 ⎤
⎢Vβ ⎥ = E 3 ⎨δi p⎜ 3 (i − 1) ⎟ ⎢0⎥ + δi + 1 p ( 3 i ) ⎢0⎥ ⎬
⎠⎣ ⎦
⎣ ⎦
⎣ ⎦⎭
⎩ ⎝
10
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Table 4-2. Sector expressions
Sector
1
T1= τ1+ τ2+ τ0
T2= τ2+ τ0
T3= τ0
2
T1= τ2+ τ0
T2= τ3+ τ2+ τ0
T3= τ0
3
T1= τ0
T2= τ3+ τ4+ τ0
T3= τ4+ τ0
4
T1= τ0
T2= τ4+ τ0
T3= τ5+ τ4+ τ0
5
T1= τ0+ τ6
T2= τ0
T3= τ0+ τ5+ τ6
6
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T1= τ0+ τ1+ τ6
T2= τ0
T3= τ0+ τ6
4.3 Current Measurement Stage
Three identical shunts are used to read the current Ia,Ib and Ic. These values should
be amplified to be in the range of the ADC. Indeed, if we measure current of several
milliamps (500mA), the maximum voltage is around 0.025V.
Figure 4-6. Amplifier stage
R
R
Shun
R
VA
R
ia
ADC
+
V1
V2
V1
V
R
V2
Offset
For example:
Vs = Offset +
R2
(V 2 − V 1)
R1
When measuring the three currents Ia,Ib and Ic, only two measures are required,
indeed Ia + Ib + Ic = 0.
Figure 4-7. ADC and PWM synchronization
T
T
T1
PWM
ADC
tm
t
tm
tm
The ADC measures are done every period of the PWM. The first ADC measure
should be done in the time range named tm. This time is the minimum time where
none of the 3-phases are driven.
For example:
In case of sector 1, T1 is the longest time so it means that T1 > T-tm, in that case it is
not possible to measure Ia. So Ib and Ic are measured and Ia is derived from the two
others measures with the equation Ia = –Ib –Ic.
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4.4 Current regulation and speed Regulation 4
In order to reduce time consuming effect of regulator, we have used the Integrator
Proportional (IP) regulator.
4.4.1 Current Regulation
In a continuous domain, the closed loop has the mathematical expression:
Id =
Ki
Idref
L c s + ( R + Kd ) s + K i
2
It is possible to easily identify the second order of the transfer function:
a
s + 2ε ω n s + ωn
2
With Ki =
Lcω n
2
2
and Kd = 2εω n Lc − R
These correctors have been chosen to have a depreciation rate ε =2 and a response
time of 5℅ (TrWn).
Response Time
Figure 4-8. Response time vs Depreciation rate.
Depreciation rate
For that
ωn = 2 R L c with
Ki = 4 R 2 Lc and Kd = 7. R
4.4.2 Speed Regulation
The external closed loop for speed regulation has the following mathematical
expression:
Ω
Ki
a
=
= 2
2
Ωref J s + Kdv s + Kiv s + 2ε ω n s + ωn 2
With
4
ωn2 =
Kiv
Kdv
et 2 ε ωn =
J
J
The PI regulator is implemented as a software library component in the software
package associated with this application note. See also section 5.
32126A-AVR32-06/09
We choose ωn=0.1R/Lc and ε=2, So Kiv = 0.01
R2
R
J et Kdv = 0.4 J
2
Lc
Lc
4.5 Execution Time and Regulation Loop
The following table gives the number of operations for each function
Table 4-2. Operations costs
Function
Add
Mul
Div
Shift
7
0
0
17
2
4
0
62
2
4
0
62
Regulation
7
4
0
124
Decoupling 5
3
5
0
62
SVPWM
27
0
0
354
Concordia
abc-to- αβ
Clark
αβ-to-dq
Clark Inv
dq-to- αβ
5
The decoupling stage is the stage to separate torque and power loss regulations
after the current measurement stage. The idea is to be sure to only regulate torque
(without disturbing the power loss loop).
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4.6 General Algorithm
As shown in Figure 4-9, the regulation_loop_task() process is sequenced on tick
reference (every 100µs). This task synchronizes current measurement and computes
all mathematical transformations to execute the Field Oriented Control algorithm.
Inside this task, there are two regulation loops interlinked:
- Current regulation loop.
- Speed regulation loop.
Figure 4-9. Regulation Loop Task Step Machine
regulation_loop_task()
Hall Interrupt
No
MC_current_measurement()
Current measurement of
the 3-phases
hall_estimator_update()
Update Teta and Speed
values
Clarke()
Realize the Clarke
Transformation
Wait
Yes
Compute new Teta and
Speed
Realize the Park
Transformation
park()
Speed
Regulation?
No
Yes
Proceed Speed
Regulation
Execute Speed
Regulation
²
park_inv()
Realize the Inverse
Park
Transformation
Current Regulation
Execute Current
Regulation
svpwm()
Compute new
vectorial command
Message Ready?
Sleep()
32126A-AVR32-06/09
Prepare New Message
for the HMI CDC Task
5 Source Code Architecture
5.1 Software Architecture
Figure 4-10. Software Architecture
Field Oriented Control application
main.c
CDC communication
task
HMI
Motor Control
regulation_loop_task() mc_control.c
usb_task() device_cdc_task.c
device_cdc_task()
Motor Driver
mc_driver.c
Motor Control Library
PI Regulator
PARK
Space Vector Modulation
SERVICES/MOTOR//PI
SERVICES/MOTOR/PARK
HALL ESTIMATOR
SERVICES/MOTOR/HALL
SERVICES/MOTOR/SVPWM
CLARKE
SERVICES/MOTOR/CLARKE
DRIVERS
usb.c adc.c pwm.c flashc.c pm.c gpio.c
This application does not require any operating system to run. The main() function is
in charge of calling the software «tasks» (using a scheduler) realizing FOC algorithm
computation and USB communication with the Communication Device Class (CDC)
for HMI management. There are 2 tasks:
•
regulation_loop_task()The regulation task that computes all calculation for
dedicated FOC algorithm.
•
usb_task() / device_cdc_task()The USB Task: This task is in charge of the
CDC communication management.
The main loop of the application is a simple free-running task scheduler:
while(TRUE)
{
#ifdef USB_DEBUG
usb_task();
device_cdc_task();
#endif
mc_regulation_task();
}
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5.2 Package
The EVK1101-SENSOR-FIELD-ORIENTED-CONTROL-X.Y.Z.zip contains projects
for AT32UC3B0256 RevF or later:
•
EVK1101-SENSOR-FIELD-ORIENTED-CONTROL-X.Y.Z
Default hardware configuration of the project is to run on the EVK1101 board,
although any board can be used (refer to section 5.5.5)
5.3 Documentation
For full source code documentation, please refer to the auto-generated Doxygen
source code documentation found in:
•
AVR32723/APPLICATIONS/EVK110x-MOTOR-CONTROL/BLDCFOC/EXAMPLE/readme.html
5.4 Projects/ Compiler
The IAR™ project is located here:
•
src/ APPLICATIONS/EVK110x-MOTOR-CONTROL/BLDC-FOC/EXAMPLE/IAR/
The GCC makefile is located here:
•
src/ APPLICATIONS/EVK110x-MOTOR-CONTROL/BLDC-FOC/EXAMPLE/GCC/
The Avr32Studio project is located in the root-dir of the package:
-./
5.5 Implementations Details
5.5.1 Main()
The main() function of the program is located in the file:
•
src/APPLICATIONS/EVK110x-MOTOR-CONTROL/BLDC-FOC/EXAMPLE/main.c
This function will:
•
Initialize PWM outputs for Space Vector Generation.
•
Initialize ADC inputs for 3-phases current measurement.
•
Initialize USB connection for CDC HMI connection.
5.5.2 Motor Control Library
The motor control library is located here:
•
src/SERVICES/MOTOR_CONTROL/
This folder delivers:
•
The Park and Clarke transformations explained in section 4.1.1 are delivered in
the folder src/SERVICES/MOTOR_CONTROL/PARK_CLARKE/
•
The Space Vector Modulation explained in section 4.2.1 is delivered in the folder
src/SERVICES/MOTOR_CONTROL/SVPWM/
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5.5.3 HMI CDC Task
The HMI CDC Task is located here:
•
src/APPLICATIONS/EVK110x-MOTOR-CONTROL/BLDCFOC/EXAMPLE/device_cdc_task.c
This task receives and sends messages through the USB communication.
With:
•
The message definition located in
src/APPLICATIONS/EVK110x-MOTORCONTROL/BLDC-FOC/EXAMPLE/ENUM/frame.h
5.5.4 AT32UC3B Drivers
The example firmware uses the AVR32 UC3 driver library available in
•
src/UTILS/LIBS/DRIVERS/AT32UC3B/
5.5.5 Board File Definition
The application is designed to run on the EVK1101. All projects are configured with
the following
define: BOARD=EVK1101. The EVK1101 definition
src/BOARDS/EVK1101 directory.
can
be
found
in the
5.5.5.1 Board customization
For IAR project, open the project options (Project -> Options), choose the «C/C++
Compiler», then «Preprocessor». Modify the BOARD=EVK1101 definition by
BOARD=USER_BOARD. For GCC, just modify in the config.mk file
(src/APPLICATIONS/EVK110x-MOTOR-CONTROL/BLDC-FOC/EXAMPLE/GCC) the DEFS
definition with –D BOARD=USER_BOARD. For Avr32Studio, open the project
properties (Project -> Properties), go in the «C/C++ build», then «Settings», «tool
settings» and «Symbols». Modify the BOARD=EVK1101 definition by
BOARD=USER_BOARD.
5.6 Project Configuration
The project configuration files can be found in the src/APPLICATIONS/EVK110xMOTOR-CONTROL/BLDC-FOC/EXAMPLE/CONF/ directory.
Configuration files are not linked to IAR, GCC or Avr32Studio projects. The user can
alter any of them, then rebuild the entire project in order to reflect the new
configuration.
/CONF: configuration header files of demo modules:
CPU settings , Peripheral Clock settings and Motor settings
5.7 GUI Application
The GUI application installer is located here:
•
src/APPLICATIONS/EVK110x-MOTOR-CONTROL/BLDC-FOC/LABVIEW/FOC_Gui.msi
The USB driver is located here:
•
18
src/APPLICATIONS/EVK110x-MOTOR-CONTROL/BLDC-FOC/LABVIEW/usb_cdc.inf
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5.8 CPU Cost and Memory Usage for Sensor Field Oriented Control algorithm.
All results are given using IAR Workbench 5.3 compiler revision 3.10A with speed
optimization level and Hmatrix optimization.
Criteria
Result
CPU Occupation
35% with a tick
value of 100 us at
42MHz.
Code Size
17Kb
Data
13Kb
Const
3.5Kb
5.9 Limitation of the Sensor Field Oriented Control algorithm.
All the application has been implemented with a fixed point library written in a 32-bit
format (Q1.31) 6.
The usage of this library allows accelerated computations but it generates some
limitations in the variation range of each variable.
For example, when computing current regulation, every ADC samples are scaled by a
variable named E. This variable matches a ratio of the bus voltage. In the current
implementation, this variable has been fixed to half of the nominal voltage of the
motor. In that case, the nominal speed is equal to 2000 rpm.
6
See the application note:
http://www.atmel.com/dyn/resources/prod_documents/doc32076.pdf for more details.
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5.10 Compiling the application
The following steps show you how to build the embedded firmware according to your
environment.
5.10.1 If you are using AVR32Studio
•
Launch avr32Studio
•
Create a new AVR32 C project («File» -> «new» -> «AVR32 C Project»).
•
Fill-in the dialogue box with project name, set target MCU to UC3B0256 and
press finish.
•
Choose Import archive file («File» -> «import»…), press the “next” button.
•
Select the EVK1101-SENSOR-FIELD-ORIENTED-CONTROL-X.Y.Z.zip archive
file with the browse button. Select «into folder», check «Overwrite existing
resources without warning» and press the “finish” button.
•
The project is now available in the given project name.
•
Press the build button
•
Load the Code: Please refer to the application note AVR32723: AVR32 Studio
getting started
5.10.2 If you are using GCC with the AVR32 GNU Toolchain
•
Open a shell, go to the src/APPLICATIONS/EVK110x-MOTOR-CONTROL/BLDCFOC/EXAMPLE/GCC/ directory and type:
make rebuild program run
5.10.3 If you are using IAR Embedded Workbench® for Atmel AVR32
•
Open IAR and load the associated IAR project of this application (located in the
directorysrc/APPLICATIONS/EVK110x-MOTOR-CONTROL/BLDCFOC/EXAMPLE/IAR)
20
•
Press the “Debug” button at the top right of the IAR interface.
•
The project should compile. Then the generated binary file is downloaded to the
microcontroller to finally switch to the debug mode.
•
Click on the “Go” button in the “Debug” menu or press F5.
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5.11 Start the PC application
•
Plug the EVK1101 to the PC through a USB Connection.
•
The USB enumeration should start; a new serial port appeared in Windows.
•
Power-up the power bridge.
5.11.1 Field Oriented Control GUI
Once the GUI is launched, the user can select a serial port number and connect the
application.
Figure 4-11. Field Oriented Control GUI
Iq
Speed
Id
Serial port
5.11.1.1 Increase Speed Value
When the speed reference increases with constant resistive torque value, the Iq
increases smoothly to target the new speed value. The Id remains at ‘0’.
Figure 4-12. Increase Speed Value Step
Speed
Iq
When the user want to increase speed value
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5.11.1.2 Increase Resistive Torque Value
The resistive torque value increases so the measured speed value decreases. To
compensate it, the FOC algorithm should increase the Iq reference and finally the
speed is regulated. The Id remains at ‘0’.
Figure 4-13. Increase Resistive Torque Value Step
Speed
Iq
22
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6 Reference
[1] Commande vectorielle sans capteur de position d'une machine synchrone à
aimants permanents – Atmel Nantes & IREENA[2] NI LabWindows™/CVI http://www.ni.com/lwcvi/
32126A-AVR32-06/09
7 Appendix
Figure 14. Hardware Schematic.
24
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