Reference Design Gate driver for M20XP(E) Power Modules GD-M20x for MNPC Modules Rev.6 Reference Design no.: RD_2013-06_001-v01 Table of Contents 1 In tr o d uc t i o n ........................................................................................... 3 2 Fe at ur es of Dr i v er B o a r d ......................................................................... 5 2. 1 Ma i n Fe a tur es ........................................................................................ 5 2. 2 E lec tr ic al P ar am et er s .............................................................................. 6 2. 3 Ch a nn e l As s i gnm e nt ............................................................................... 7 2. 4 P in as s i g nm ents an d c on n ec t ors f or o per a ti o n .......................................... 8 2. 5 Mec h an ic a l D im ens io n s ........................................................................... 9 3 Des c r i pt i o n of El ec tr ic a l P arts ............................................................... 10 3. 1 P o wer M o du l e ...................................................................................... 10 3. 2 Re q ui r e d p o wer s u p pl i es ....................................................................... 10 3. 3 In p ut / o ut p ut s ig n als ............................................................................ 10 3. 4 T her m is to r ou t pu t ................................................................................. 10 3. 5 PC B – P o wer S u pp l y ............................................................................. 12 3. 6 PC B – CT R In p ut a n d O u t pu t ................................................................ 14 3. 7 PC B – T h er m is to r ................................................................................. 17 3. 8 PC B – B oos te r ..................................................................................... 18 4 S hor t C ir c u i t Pr o tec t io n ......................................................................... 20 5 BO M .................................................................................................... 25 5. 1 BO M T h er m al Mo d ul e ............................................................................ 25 5. 2 BO M C on tr o l Mo d ul e ............................................................................. 25 5. 3 BO M C ur r e n t B oos t er Mo d u le ................................................................ 25 5. 1 BO M P o wer Su p p l y M od u l e ................................................................... 26 5. 2 BO M M as t er ......................................................................................... 26 5. 3 BO M S l a ve ........................................................................................... 26 Disclaimer: The information in this document is given as an indication for the purpose of implementation only and shall not be regarded as any description or warranty of a certain functionality, condition or quality. Vincotech does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights, nor the rights of others. The statements contained herein, including any recommendation, suggestion or methodology, are to be verified by the user before implementation, as operating conditions and environmental factors may vary. It shall be the sole responsibility of the recipient of this document to verify any function described herein in the given practical application. Vincotech GmbH hereby disclaims any and all warranties and liabilities of any kind (including without limitation warranties of noninfringement of intellectual property rights of any third party) with respect to any and all information given in this document. 1 Introduction This application note describes the Evaluation Driver Kit for the module family M20x or in other words the flowMNPC 4w generation. The topology used in these modules is the Mixed voltage Neutral Point Clamped which has 1200 V components in the half bridge and 600 V components in the neutral path. The board provides a plug and play solution identifying the switching behavior and efficiency of this module family. This module family is available as a single phase module as well as a three phase module. The single phase module types can be paralleled to achieve a higher output current. Detailed information is available in Vincotech’s webpage www.vincotech.com. This is the first module that carries a high power PCB with capacitors to achieve a low inductance design. The following picture shows the driver boards with an IGBT module. It is a kit with four different subsystems. This kit can be used to drive the complete range of M20XP(E) modules. Current Boost PCB Power supply PCB Controller PCBs for input and output signals PCB for thermistor signal conditioning Figure 1: Evaluation driver board with a single phase module Ordering number is listed below. Module 1 Phase system 3 Phase system M200P M208P M209P 1 X GD-M200-Master M200E M208E M209E 1 X GD-M200-Master + 2 X GD-M200-SLAVE 3 X GD-M200-Master Table 1: Ordering number GD-M20x for MNPC Modules Page 3 of 26 This ordering number will include all necessary boards to drive a complete phase. To drive the threephase modules, indicated with an E at the end, three kits are necessary, one Master and two Slaves for parallel operation, and for a 3 Phase system three Master drives are needed. Three phase connection: M20X P M20X E PWM u PWM u U GD-M200-Master U GD-M200-Master M20X P PWM v PWM v V GD-M200-Master V GD-M200-Master M20X P PWM w PWM w W GD-M200-Master W GD-M200-Master DC+ GND DC- DC+ GND DC- Single phase connection: M20X P M20X E PWM u GD-M200-Slave PWM U GD-M200-Master V GD-M200-Master DC+ GND DC- GD-M200-Slave DC+ GND DC- The next chapter describes the main features, basic electrical parameters as well as pin assignments and mechanical dimensions. GD-M20x for MNPC Modules Page 4 of 26 2 Features of Driver Board The next chapter describes the main features, basic electrical parameters as well as pin assignments and mechanical dimensions. 2.1 Main Features Four drivers for each switch Single 15 V power supply with 3000VAC isolation Gate voltage of -8 V / +16 V Voltage for each switch is generated by a DC/DC converter Non-inverting PWM inputs Input and output signals 0 V / +5 V Alternative input and output signals by fiber optics Desaturation protection Two steps turn-off with 10 V intermediate level Active miller clamp Under voltage lockout Fault output signal (active high) for each switch Heatsink temperature sense with thermistor Gate drive current of ±20 A peak PCB designed to fulfill the requirements of IEC61800-5-1, pollution degree 2, over voltage category III GD-M20x for MNPC Modules Page 5 of 26 2.2 Electrical Parameters The electrical characteristics involve the guaranteed value spread for the supply voltage, load and processes. Unless otherwise noted all voltages are given with respect to ground (GND). Positive currents are assumed to be flowing into pins. min. typ. max. Unit Remarks UCE – max for 600 V switches 600 V UCE – max for 1200 V switches 1200 V Pmax – max output power supply 2 W US – supply voltage for drivers 14,5 15 15,5 V See note 1 IS – Input current no load / full load 30/250 mA For 1 dc/dc converter UCC – supply voltage for logic 4.5 5 5.5 V Uge_x – On voltage for logic inputs 4.5 5 5.5 V Uge_x – Off voltage for logic inputs -3 0 0.8 V UVLO top threshold Under voltage lockout 14 14,5 15 V UVLO bottom threshold Under voltage lockout 13 14 14,5 V Desaturation protection 7 V fsw – switching frequency 8 16 kHz See note 2 Ta – Ambient temperature -25 70 °C TST – Storage temperature -40 85 °C For additional information refer to the datasheet of TD350 from ST and the datasheet of the HCNW2611 from Avago Technologies Note 1: The secondary voltage for the gate drive will change with the same ratio. Note 2: Limitation by IGBT losses Table 2: Electric parameters The following table shows different modules available in the M20xy series. Here information about the recommended switching frequency and the assembled passive components are mentioned. The last letter P indicates a single phase module whereas the E indicated a three phase module. Module M208P M209P M200P Nominal chip current [A] 300 400 600 1 Frequency [kHz] 40 30 20 Gate resistors RG_ext on [Ω] 1.25 1.25 1.25 Gate resistors RG_ext off [Ω] 1.25 1.25 1.25 Gate emitter resistor RGE [Ω] 15K 15K 15K 2 Gate emitter capacitor CGE [µF] n.a. n.a. n.a. 1 : Limit given by the output power of power supply 2 : not assembled Table 3: Members of M20x family GD-M20x for MNPC Modules M208E 300 40 1.25 1.25 15K n.a. M209E 400 30 1.25 1.25 15K n.a. M200E 600 20 1.25 1.25 15K n.a. Page 6 of 26 2.3 Channel Assignment The evaluation driver kit consists of four channels for the IGBTs and an additional channel for the thermistor. T4 T1 T3 T2 NTC fault output PWM input Figure 2: Assignment for channels GD-M20x for MNPC Modules Page 7 of 26 2.4 Pin assignments and connectors for operation The driver board has connectors to provide the power to the PCB and to support signals to e.g. the driver circuit. 1 2 3 4 P17 – Power Supply +15 V GND P200 – Signal VCC Fault - Output GND PWM - Input P300 – Thermistor VCC Temp - Output D_GND nc 1 2 3 4 -for each channel U200 – Input signal -SFH551/1-1V digital receiver for optical data transmision -optical fiber: unconnectorized 2.2mm polymer 650nm -for each channel U201 – Output signal SFH756V transmitter for optical data transmission with polymer optical fiber 2,2 mm 650nm -one per module U5 – Output thermistor -SFH756V transmitter for optical data transmission with polymer optical fiber 2,2 mm 650nm Table 4: Pin assignment for connectors GD-M20x for MNPC Modules Page 8 of 26 2.5 Mechanical Dimensions Mechanical dimensions for width, length and height (without module): 98 mm x 95 mm x 46 mm 98 mm Figure 3: PCB of boost stage GD-M20x for MNPC Modules Page 9 of 26 3 Description of Electrical Parts This chapter describes the different electrical parts like the input signals, output signals and driver circuit for a better understanding how the board works. 3.1 Power Module This power module family is suitable for PV applications and for UPS applications. M20xE(P) modules are available in single phase and in three phase configuration based on a mixed voltage neutral point clamped topology which is also known as NPC2 topology. Two 1200V IGBTs with freewheeling diodes are implemented for the half bridge. Two 600V IGBTs with freewheeling diodes are placed between the neutral point and the output. The IGBTs and the freewheeling diodes have the same current rating. For temperature measurement a NTC is equipped. Note that this NTC has only a functional isolation. 3.2 Required power supplies To ensure a correct operation of the evaluation kit one single 15 V power supply for all gate drivers of a single phase module is enough. The 15 V has to be supported through the connector P17. A 5 V power supply ensures the input and output signals for the logic. This has to be applied on each channel as well as on the PCB with the thermistor measurement. 3.3 Input / output signals As mentioned each channel needs a 5 V power supply. The voltage can be supplied with one single power supply. No isolation between the channels is needed. The switching of the IGBT inverter needs to be controlled by 4 channels for each phase. The dedicated connector for input signals is the connector P200. Each switch has its own fault output activated by under voltage lockout or by desaturation supported through the same connector. The output of the thermistor is a PWM signal. All inputs U200 and outputs U201 are available as optical signals through fibre optic connectors. 3.4 Thermistor output The thermistor output is generated with a voltage-controlled pulse width modulator. It is supported to the connector P300 and the fiber optic connector U5. This PCB needs a 5 V power supply as well. The attached diagram gives the duty cycle and input modulation voltage as a function of the NTC temperature which is build in the power module. GD-M20x for MNPC Modules Page 10 of 26 Duty Cycle & V mod vs. Temperature 80 1,10 1,05 1,00 0,95 0,90 0,85 0,80 0,75 0,70 0,65 0,60 0,55 0,50 0,45 0,40 0,35 0,30 0,25 0,20 0,15 0,10 0,05 0,00 70 60 50 40 30 20 10 0 25 30 35 40 45 50 55 60 Vmod 65 70 75 80 85 90 95 100 105 110 115 120 125 Measured Duty Cycle Figure 4: Duty cycle of thermistor output GD-M20x for MNPC Modules Page 11 of 26 3.5 PCB – Power Supply The power supply board supports all four channels of the M20x evaluation kit. A 15 V power supply has to be used to support the 2-pin connector in the middle of the PCB (P17). Four independent DC/DC converters are used on this board to generate +16 V / -8 V for each IGBT. T4 T1 T3 T2 NTC Figure 5: PCB of power supply The asymmetric bipolar voltage for the IGBTs is generated by a DC/DC converter IG136-15 Figure 6: Bipolar voltage supply for e.g. T3 – neutral point low side The DC /DC converter (IG136-15) is a 2 W 15V input, +17V/-8,7V output with 3000VACrms I/O isolation. Different connectors are used on the bottom side of the power supply PCB to supply the signals from the input, output and thermistor PCB to the boost PCB. Additional connectors on the bottom side of the power supply PCB are used for Master-Slave operation. This configuration can be used to parallel e.g. three M200P modules. GD-M20x for MNPC Modules Page 12 of 26 Female connectors for boost PCB Male connectors for parallel operation Figure 7: Connector for boost PCB and parallel operation The pin assignment for the bottom connectors is like the following: Connectors for boost PCB Connectors for parallel operation Pin Signal Comment Pin Signal Comment 1 desat np H Desaturation protection 1 desat np H Desaturation protection 2 +16V np 1-2 Positive supply voltage 2 +16V np 1-2 Positive supply voltage 3 out H np H Output for high signal 3 out H np H Output for high signal 4 out L np H Output for low signal 4 out L np H Output for low signal 5 -8V np 1-2 Negative supply voltage 5 -8V np 1-2 Negative supply voltage 6 clamp np H Clamp 6 clamp np H Clamp 7 npGND 1-2 Ground 7 npGND 1-2 Ground 8 nc not connected 8 nc 9 nc 10 nc Table 5: Pin assignment for connectors, e.g. T2 – neutral point high side GD-M20x for MNPC Modules Page 13 of 26 3.6 PCB – CTR Input and Output Four additional vertical mounted PCBs provide the PWM input signals for the IGBTs as well as fault signals coming from the IGBTs. Receiver Transmitter 5 V supply Input / Fault Figure 8: CTR- PCB with TD350E A 5 V power supply is required for each input and output PCB. A common power supply can be used. Two different options are available to drive the IGBT. One is through a usual connector on the left side. The other is with fiber optics. One pin / fiber supports the PWM switching signal for the IGBT and the other supports a fault signal back. The pin assignment is shown in Table 4. GD-M20x for MNPC Modules Page 14 of 26 An opto coupler in widebody package provides the isolation between the user side and the power side for each signal direction. The green LED indicates that a voltage is applied on the secondary side. In this case the supply voltage comes from the power supply PCB. The red LED starts lightning when a fault is detected. A voltage regulator generates the 5 V secondary supply voltage for the input opto coupler and the receiver fiber out of the 16 V coming from the power supply PCB. The IGBT driver IC is the TD350E Features of the IGBT gate driver IC Active Miller clamp feature Two-level turn-off with adjustable level and delay Desaturation detection Fault status output Negative gate drive capability UVLO protection 2 kV ESD protection (HBM) Activ Miller clamp: During turn-off, the gate voltage is monitored and the clamp output is activated when gate voltage goes below 2 V (relative to GND). The clamp voltage is VL+3 V max. for a Miller current up to 500 mA. The clamp is disabled when the IN input is triggered again.The current capability of the clamp output is increased by an external PNP bipolar transistor placed on the current booster PCB ( bottom PCB). Two-level turn-off: The two-level turn-off is used to increase the reliability of the application. During turn-off, gate voltage can be reduced to a programmable level (set by D201 to a 10 V) in order to reduce the IGBT current (in the event of overcurrent). This action prevents both dangerous overvoltage across the IGBT and RBSOA problems, especially at short-circuit turn-off. The two-level turn-off (Ta) delay is programmable through an external resistor (R205) and capacitor (C208) for accurate timing use the following equation : Ta [μs] = 0.7 • R205 [kΩ] • C208 [nF] Ta is set to 1,5 μs Turn-off delay (Ta) is also used to delay the input signal to prevent distortion of input pulse width. Desaturation detection: When the desat voltage goes higher than 7 V, the output is driven low (with 2-level turn-off). The FAULT output is activated. The FAULT state is exited at the next falling edge of IN input. A programmable blanking time is used to allow enough time for IGBT saturation. The blanking time is made of an internal 250μA current source and an external capacitor (C252).The high voltage diode blocks the high voltage during IGBT off state (a standard 1kV ); the 1kΩ resistor filters parasitic spikes and also protects the DESAT input. During operation, the DESAT capacitor is discharged when TD350 output is low (IGBT off). When the IGBT is turned on, the DESAT capacitor starts charging and desaturation protection is effective after the blanking time (tB) tB =7.2VC252 / 250μA When a desaturation event occurs, the fault output is pulled down and TD350 outputs are low (IGBT off) until the IN input signal is released (high level), then activated again (low level). C252=100pF GD-M20x for MNPC Modules Page 15 of 26 Fault status output: the dedicated output pin of the IC is used to signal a fault event (desaturation, UVLO) to a controller. The fault pin drives direct the OP 201 optocupler via a red colored LED. When a fault event is detected the red LED will ligt up. Minimum ON time:In order to ensure the proper operation of the 2-level turn-off function, the input ON time(Twin) must be greater than the Twinmin value: Twinmin = Ta + 2 • Rdel • C208 = 1,5 +2*0,5*0,47=2μs Rdel is the internal discharge resistor of TD350E 0,5 kΩ (from the datasheet of TD350E) Input signals smaller than Ta are ignored. Input signals larger than T winmin are transmitted to the output stage after the Ta delay with minimum width distortion ( ΔTw = Twout - Twin). For an input signal width Twin between Ta and Twinmin, the output width Twout is reduced below Twin (pulse distortion) and the IGBT could be partially turned on. These input signals should be avoided during normal operation. For more details see : http://www.st.com/web/en/resource/technical/document/datasheet/DM00023850.pdf GD-M20x for MNPC Modules Page 16 of 26 3.7 PCB – Thermistor One vertical mounted PCB measures the NTC and provides electrical and optical information. These PCBs are not equipped with a connector in newer driver kit versions but soldered direct into the power supply PCB. Transmitter 5 V supply Output Figure 9: TH-PCB with LTC6992-1 (Voltage-Controlled Pulse Width Modulator) A 5 V supply is required to power this PCB. The same power supply as for the Input and Output PCB can be used. Two different options are available. One is through a usual connector on the left side. The other is with fiber optics. An opto coupler in widebody package provides the isolation between the user side and the power side. A voltage regulator generates the 5 V secondary supply voltage for the opto coupler out of the 16 V coming from the power supply PCB GD-M20x for MNPC Modules Page 17 of 26 3.8 PCB – Booster The boost PCB provides the needed gate current to drive the IGBTs. Four independent driver channels are assembled. It is supplied by the power supply PCB with +16 V and -8 V. T1 T2 P9 P11 T4 NTC P15 T3 P13 Figure 9: Current Booster PCB The pin assignment for the connectors is like the following: Connector P9, P11, P13, P15 Pin Signal P9 Signal P11 Signal P13 Signal P15 Comment 1 desat desat desat desat Desaturation protection 2 +16 V +16 V +16 V +16 V Positive supply 3 out high out high out high out high Signal for turn-on 4 out low out low out low out low Signal for turn-off 5 -8 V -8 V -8 V -8 V Negative supply 6 clamp clamp clamp clamp Miller clamping 7 GND GND GND GND Ground 8 n.c. n.c. n.c. n.c. not connected 9 NTC NTC 10 +5 V Supply for NTC Table 6: Pin assignment for connectors, e.g. T3 – neutral point high side The PCB has two current boost stages that are connected in parallel to provide a high gate current when necessary. The module has two gate pins. Each for half of the nominal module current. A common gate resistor as well as separated gate resistors are used for the gates and the common emitter. The schematic to drive the IGBT is shown in the next figure as an example for T1. The schematics for T2 – T4 are the same. GD-M20x for MNPC Modules Page 18 of 26 Figure 10: Boost stage of T1 Figure 11: Boost stage GD-M20x for MNPC Modules Page 19 of 26 4 Short Circuit Protection The short circuit protection has been tested by using critical inductance for the short (Sc). Critical inductance means that the inductance is so small that dI/dt is high enough not to be able to be detected by the current sensing of the inverter. On the other hand the inductance is so big that the IGBT can temporary saturate due to the high dI/dt and so the IGBT has to withstand du/dt after the short circuit protection is activated by the desaturation sensing. The interpretation of the curves is the following. At „0“ time the T2 IGBT is getting a positive gate voltage and it saturates. The emitter voltage, „magenta“ rises to the collector voltage, „green“. The current, „blue“ on the short circuit impedance starts to increase rapidly. Current range is 1000A / DIV. At about 4000A collector current the IGBT desaturation sensing is activated and the soft turn off is initiated, At „1“ time the gate drive circuit switches to the first turn off level of 10Vs. At time „2“ the IGBT desaturates in a soft manner due to the reduced gate drive voltage and the gate drive settles to 10V. As the IGBT is not turned off, there is no dangerous du/dt to cause RBSOA infringement and the overvoltage spike on the IGBT is also small. The short circuit current at a value of about 5000A partly commutes into the freewheeling diode (inverse diode of T4). The IGBT is conducting a current limited by its transfer current characteristics at 10V gate voltage. At time „3“ the IGBT gate voltage is totally switched off to -8V and the IGBT releases the rest of current. As the majority of the short circuit current is already flowing through the freewheeling diode and as there is no voltage change on the IGBT (du/dt) at this moment there will be no dangerous voltage overshoot and turn off safe operating area for the IGBT will be fulfilled. GD-M20x for MNPC Modules Page 20 of 26 Figure 13: Schematic and waveforms of T2 NP high IGBT short circuit measurement The short circuit protection is checked for all 4 IGBTs. GD-M20x for MNPC Modules Page 21 of 26 Figure 14: Schematic and waveforms of T3 NP low IGBT short circuit measurement GD-M20x for MNPC Modules Page 22 of 26 Ucc T1 15V Uce Sc 700V D2 D3 T2 T3 15V 15V Uge V 1mH T4 Scope GND V Ic 0.000003 0.00001 Q Q Q Q Q Q 0.000003 Figure 15: Schematic and waveforms of T4 HB low IGBT short circuit measurement GD-M20x for MNPC Modules Page 23 of 26 Figure 16: Schematic and waveforms of T1 HB high IGBT short circuit measurement GD-M20x for MNPC Modules Page 24 of 26 5 BOM 5.1 BOM Thermal Module 5.2 BOM Control Module 5.3 BOM Current Booster Module GD-M20x for MNPC Modules Page 25 of 26 5.1 BOM Power Supply Module 5.2 BOM Master 5.3 BOM Slave GD-M20x for MNPC Modules Page 26 of 26