The IS200BPIAG1A IGBT Drive Bridge Personality Interface Board is a critical interface component designed by GE Industrial Control Systems for IGBT-based three-phase AC drive systems. The IS200BPIAG1A provides a complete and reliable signal interface between the control electronics and the power electronics, serving as the core bridge that enables high-performance control and safe operation of the drive system. The IS200BPIAG1A is mounted in a standard VME-type board rack and interfaces with the control system backplane through its P1 connector. It is directly connected to the IGBT power devices of phases A, B, and C through six phase-dedicated plug connectors.
The IS200BPIAG1A integrates six independently isolated IGBT gate driver circuits, three isolated shunt Voltage Controlled Oscillator (VCO) current feedback circuits, and isolated VCO feedback circuits for monitoring the DC link voltage and the VAB and VBC output voltages. Additionally, the IS200BPIAG1A board features built-in hardware-level phase overcurrent and IGBT desaturation fault protection, providing a comprehensive, localized protection system for the IGBT power bridge. All these functions are integrated onto a single standard VME form-factor board, demonstrating GE's highly integrated and modular design philosophy for power electronics interfaces.
Power Supply System Design
The power supply system of the IS200BPIAG1A employs a highly isolated design scheme to ensure electrical safety between phases and between the high-voltage and low-voltage sides. The isolated power for the board is derived from the secondary windings of three transformers, one dedicated to each phase. A 17.7 V AC square wave signal supplied through the P1 connector powers the transformer primaries. For each transformer:
Gate Drive Power Supplies: Two of the three secondary windings are half-wave rectified and filtered to produce the isolated +15 V (VCC) and -7.5 V (VEE) supplies required by the upper and lower IGBT gate driver circuits. These provide the necessary positive and negative bias voltages to ensure reliable turn-on and turn-off of the IGBTs.
Signal Processing Power Supply: The third secondary winding is full-wave rectified and filtered to provide the isolated ±12 V required by the shunt current feedback circuits, phase voltage feedback VCO circuits, and fault detection circuitry. Additionally, a 5 V linear regulator on the +12 V supply generates a light-duty 5 V logic supply.
Control Logic Power: The +5 V reference supply required for the system control logic is provided directly to the IS200BPIAG1A board through the P1 connector.
The overall power requirements for the IS200BPIAG1A are clearly defined: a maximum of 1.5 W from the +5 V DC supply, and from the 17.7 V AC supply, a maximum of 5 W without gate driver amplifier load and a maximum of 18 W with gate driver amplifier load.
IGBT Gate Drive Circuits
The IS200BPIAG1A is configured with two fully independent and isolated IGBT gate drive circuits for each phase leg: one controlling the upper IGBT and the other controlling the lower IGBT. This totals six driver circuits for the three phases. Each circuit is composed of an optically isolated hybrid gate drive module and a small number of discrete components.
Drive Characteristics and Protection Functions: The gate drive module drives the IGBT gate between VCC (+15 V) and VEE (-7.5 V), providing sufficient positive bias to ensure the IGBT is fully saturated during conduction and sufficient negative bias to ensure reliable turn-off and resistance to parasitic turn-on. The control inputs of the upper and lower modules are connected in an anti-parallel configuration to prevent simultaneous conduction, which would cause a shoot-through short circuit in the phase leg. The module features a peak sink/source current capability of 5.0 A, with a typical turn-on/turn-off delay of only 1.5 microseconds.
Fault Detection Mechanism: Each gate drive circuit can generate two types of faults:
Desaturation Fault: When the module is commanded to turn the IGBT ON, it monitors the voltage drop between the collector and emitter of the IGBT. If this voltage exceeds a typical threshold of about 10 V for a period longer than 4.2 microseconds (6.6 microseconds maximum), it indicates that the IGBT has come out of saturation and entered the linear operating region, which can rapidly lead to device overheating and damage. The module will immediately turn the IGBT OFF and annunciate a desaturation fault.
Undervoltage (UV) Fault: The module also monitors the voltage between VCC and VEE. If this voltage drops below 18 V, the gate drive voltage is insufficient to reliably drive the IGBT, and an undervoltage fault will occur. These two fault signals are OR-ed together and optically coupled back to the control logic circuit.
Shunt Current Feedback System
The IS200BPIAG1A achieves precise measurement of the output phase currents by detecting the voltage drop across a shunt resistor in each of the phases A, B, and C. The current feedback channel for each phase is fully independent and isolated.
VCO Signal Conversion: The voltage signal across the shunt is first conditioned by an amplifier and then passed to a VCO circuit, which converts it into a frequency signal. The VCO output frequency range is 0–2 MHz, and its operating point is biased so that at zero current, the nominal output is 1 MHz. The full-scale shunt voltage range is ±200 mV, corresponding to an output frequency change of ±800 kHz. This enables high-precision, real-time phase current measurement that can be easily reconstructed by the control system through simple frequency counting.
Fault Protection Functions: The current feedback circuit is also capable of detecting two types of faults:
DI/DT Fault: When the shunt current undergoes a step change of 100% or more of its rated value, the current feedback circuit can detect and report this fault within 25 microseconds, preventing system disturbance from excessive rates of current change.
Overcurrent (OC) Fault: The overcurrent threshold is set at 250% of the rated shunt current. If the current is detected to exceed this threshold, an overcurrent fault signal is immediately triggered. These two current fault signals are also OR-ed together and transmitted to the control logic side via optical isolation.
Phase-to-Phase and DC Link Voltage Feedback
VAB and VBC Phase-to-Phase Voltage Feedback: The IS200BPIAG1A ingeniously measures the output phase-to-phase voltages VAB and VBC through two channels derived from the shunt connection points. The VAB circuit is based with the phase B shunt VCO circuit and connects to phase A via a resistive attenuation network. The VCB circuit is based with the phase C shunt VCO circuit and connects to phase B via a resistive attenuation network. The output frequency range of each VCO is 0–2 MHz, with a nominal output of 976.8 kHz at zero phase-to-phase voltage. A ±1.0 V phase-to-phase voltage corresponds to an output frequency change of ±959.58 Hz. All VCO outputs are connected to the control logic via optical isolation.
DC Link Voltage Feedback: A third VCO voltage feedback circuit is dedicated to monitoring the DC link voltage. This circuit is referenced to the phase A lower gate drive circuit, with a resistive attenuation tie to the phase A upper IGBT collector connection. The VCO output range is similarly 0–2 MHz. The input is scaled so that a 0 to 1198 V DC link voltage corresponds to an output frequency of 0 to 2 MHz.
Fault Control and Gate Driver Disable Mechanism
The fault signals from the IS200BPIAG1A are transient in nature, remaining true only for the duration of the fault condition. Therefore, the control system must use a fault handling circuit via the P1 connector to latch these signals.
When any fault is detected, the IS200BPIAG1A takes decisive protective action by removing control power from all six IGBT gate driver modules. Dedicated high-speed and fail-safe disable lines in the P1 connector are provided to implement this function:
High-Speed Driver Disable: During normal operation, the DRVPC line should be logic low and +5 V should be applied to the DRVP5 line. When a fault is detected, taking the DRVPC line high initiates a high-speed gate driver disable, minimizing the protection response time.
Fail-Safe Driver Disable: Removing the +5 V power from the DRVP5 line through a set of external contacts provides a fail-safe method to disable the IGBT driver modules. Even if the high-speed disable channel fails, this contact-based method ensures the IGBTs are reliably turned off.
Board Identification and Interface Connections
The IS200BPIAG1A features a 1024-bit onboard serial memory device that is programmed with board identification and revision information, supporting an automatic plug-and-play board identification capability for the control system.
The P1 Bridge Control Connector uses a standard VME connector. A large number of pins in rows A and D are used for voltage clearance to ensure safe insulation distance between high- and low-voltage signals. Rows B and C carry all the core control signals: 17.7 V AC power input, bridge enable signals, driver power control, fault reset, desaturation/UV and shunt fault status for all three phases, gate drive command signals, VCO frequency output signals, a serial board ID line, and the switched +5 V driver power output.
The Six Phase Connectors connect directly to the three-phase IGBT power devices and are divided into: APL, BPL, and CPL (which carry the gate drive lines and shunt sensing points for each phase), and AAPL, BAPL, and CAPL (which supply the isolated power for the upper and lower driver circuits of each phase).
