First Release: April 1, 2005 Application NOTES: BG2B Universal Gate Drive Prototype Board Description: The BG2B is a two channel gate drive circuit for high power IGBT modules. The BG2B utilizes Powerex hybrid gate drivers and DC to DC converters to provide efficient switching of modules rated up to 400A. The hybrid gate drivers include high speed opto-couplers for control signal isolation and desaturation detection to protect the IGBT from short circuit conditions. The hybrid DC to DC converters provide fully isolated control power for each driving channel. The BG2B also provides an isolated fault feedback signal. Applications: Features: 1.5A, 3A or 5A Peak Output Current BG2B is designed for use with Powerex NF and A series IGBT modules. 2500VRMS isolation for control power and signals Standard AMP MTA .100 input connector Use VLA106-15242 DC to DC converter for Operates from a single 15 VDC or 24 VDC supply operation with 15 VDC control power Wide output voltage swing +15V/-8V Use VLA106-24242 DC to DC converter for operation with 24 VDC control power Compact Size 3 x 2.2 (76mm x 56mm) Ordering Information: BG2B-1515 is a kit with a bare BG2B board, two M57159L-01 and two VLA106-15242 BG2B-3015 is a kit with a bare BG2B board, two VLA504-01 and two VLA106-15242 BG2B-5015 is a kit with a bare BG2B board, two VLA503-01 and two VLA106-15242 BG2B is a bare PCB only BG2B Application Guide Peak Drive Gate Driver Typical Application* Minimum R DC/DC Converter G Part Number Current (I ) (IGBT Module Rating) OP VLA106-15242 +/- 1.5A 4.2 Up to 100A M57159L-01 for 15 VDC input VLA504-01 +/- 3A 3.0 Up to 200A VLA106-24242 VLA503-01 +/- 5A 2.0 Up to 400A for 24 VDC input * Compatible IGBT module depends on voltage rating, switching frequency and selected R . Refer to Powerex application notes for details. G Note: VLA504-01 and VLA503-01 gate drivers replace older types M57959L and M57962L. VLA106-15242 replaces the older M57145L-01 1 Figure 2: VLA106-15242, VLA106-24242 Figure 1: VLA503-01/VLA504-01/M57159L-01 Block Diagram Block Diagram 8 3.3K t Adjust 3 V Fault Latch V trip CE CC + 2 Fault 9 8 and Timer Detector V detect CE 1 V 2 IN 24V V O V 10 CC 4 1 - V EE 11 V =8.2V Z Voltage Regulator Interface 14 Control V O Current Limiter 5 180 Buffer Input 13 Opto Coupler V EE 6 Circuit Explanation: The BG2B is a basic two channel gate driver designed around the recommended application circuits for the Powerex M57159L-01, VLA503-01 and VLA504-01 hybrid IGBT gate drivers in combination with either VLA106-15242 or VLA106-24242 isolated DC to DC converters. A functional block diagram of the VLA503/504-01 and M57159L-01 hybrid gate drivers is shown for reference in Figure 1. These gate drivers are optimized for use with Powerex NF and A series IGBT modules. The drivers use a high speed open collector type opto-coupler to provide 2500VRMS isolation of control signals. The output stage is designed to provide high current gate drive with the appropriate on- and off-state bias voltages for large IGBT modules. The gate driver includes a desaturation detection circuit to provide protection against short circuit conditions. For additional detailed information on the characteristics and operation of these gate drivers please refer to the individual device data sheets. Figure 2 shows a block diagram of the VLA106-15242 and VLA106-24242 hybrid DC to DC converters. These two devices are identical except that VLA106-15242 is designed to operate from a 15 VDC input and the VLA106-24242 is designed to operate from a 24 VDC input. These DC to DC converters use a transformer to provide 2500VRMS isolation for gate drive power. The converters regulated 24VDC output is split using a resistor and zener diode to provide +15.8V and -8.2V for the hybrid gate driver. For additional detailed information on the operation of the hybrid gate drivers and DC to DC converters please see the individual device data sheets. A complete schematic and component selection guide for the BG2B is shown in Figure 3. The board will normally be operated with two input voltage sources. A 5V logic source (+V ) provides drive for the high speed L opto-couplers inside the hybrid gate drivers and pull-up voltage for the fault signal isolation optos OP1 and OP2. A control power supply (+V ) provides power for the gate driver and is connected to the primary side of the DC S to DC converters at pins 8,9 and 10,11. The +V source is decoupled with the low impedance electrolytic S capacitors C4 and C8. These capacitors are connected close to the input pins of each DC to DC converter to provide a stable, well-filtered DC source. A 150uF capacitor was selected for C4 and C8 to provide the required ripple current and filtering assuming a maximum driving load and a significant distance to the main filter capacitor of the +V supply. These capacitors will be larger than necessary if the driving load is smaller or the S V supply main filter capacitors are nearby. The DC to DC converters provide isolated gate drive power which S consists of +15.8V (V ) at pin 3 and -8.2 (V ) at pin 1 with respect to common at pin 2. The gate drive power CC EE supplies are decoupled using the low impedance electrolytic capacitors C1, C2, C5, and C6. It is very important that these capacitors have low enough impedance and sufficient ripple current capability to provide the required high current gate drive pulses. The 82uF low impedance capacitors used on the BG2B are sized to supply 5A gate pulses at a 10KHz rate. If the application is operating at lower frequency or lower peak current it may be possible to reduce the size of these capacitors. The isolated V and V supplies provided by the DC to DC converters are connected to the hybrid EE CC gate drivers at pins 4 and 6 to provide gate drive power. The hybrid gate driver amplifies the control input signal and produces high current gate drive at pin 5. The gate drive current is adjusted by selecting the appropriate series gate resistance (R ). R will normally be adjusted to provide suitable drive for the module being used G G considering dynamic performance, losses and switching noise. For more information on selecting R see G Powerex IGBT module application notes. Protection against gate voltage surges is provided by DZ1, DZ2, DZ4, and DZ5. These zener diodes also help to control short circuit currents by shunting miller current away from the gate. 2 Oscillator Rectifier