IndustrialDriveDataDrive Board & Diagnostic Database
Three-phase rectifier, DC link and IGBT inverter stage

Industrial VFD Power Stage

Generic power-stage record for industrial AC drives where incoming supply, rectifier, precharge, DC-link capacitors, braking circuit, gate driver and output bridge must be separated before condemning an IGBT module or control board.

Record facts

Input boundaryLine fuses, contactor, EMC/filter hardware and rectifier bridge
Energy boundaryPrecharge resistor/contactor and DC-link capacitor bank
Output boundaryGate driver, IGBT/IPM bridge, current sensing and motor cable
Repair valuePrevents repeat module failure after incomplete board-level repair

Service notes

  • Record the installed brand, model, input voltage class and frame size before using a generic path.
  • Never assume a displayed overcurrent trip proves the IGBT module is shorted.
  • A failed precharge stage can look like a dead drive, undervoltage, blown fuse or contactor problem depending on design.
  • After module replacement, the gate-driver and current-feedback paths must be checked before power is reapplied.

Related technical records

OC START
VFD overcurrent trip at startup or enable command

The drive trips on overcurrent immediately at run command, during initial acceleration or before the motor reaches speed.

Open →DC BUS OV
DC bus overvoltage during deceleration

The drive runs normally but trips on overvoltage when stopping, ramping down, lowering a load or decelerating a high-inertia machine.

Open →GF / EARTH FAULT
Ground fault or earth leakage trip when the VFD runs

The drive powers up but trips on ground fault, earth fault or leakage indication during enable, acceleration or when output voltage is applied.

Open →REPEAT MODULE FAILURE
IGBT or IPM module fails again after replacement

A replacement output module, IPM or IGBT pack fails during the first power-up, first run test or shortly after returning the drive to service.

Open →Circuit
VFD input rectifier, precharge and DC-link path

Routes incoming three-phase supply through protection, rectification, precharge and DC-link storage before the inverter stage is allowed to run.

Open →Circuit
VFD IGBT gate-driver and output-stage path

Connects PWM command, isolated driver supply, gate components, short-circuit protection and the output bridge to overcurrent and repeat-module-failure symptoms.

Open →Circuit
VFD braking chopper and DC-bus discharge path

Routes excess DC-link energy into braking hardware or controlled overvoltage management during deceleration and overhauling-load events.

Open →Workflow
VFD precharge and DC-link workflow

Drive reports undervoltage/precharge fault, blows input fuses or shows no-display symptoms with uncertain DC-link charging.

Open →Workflow
VFD overcurrent-at-startup workflow

Overcurrent trip appears immediately at run command, during acceleration or before stable speed is reached.

Open →Workflow
VFD repeated IGBT/IPM failure workflow

Replacement IGBT, IPM or output module fails again during power-up, enable or early load testing.

Open →