When integrating the BSM B3 into a control system, the schematic layout usually follows this logic:
At the top left of the schematic, you will see three input terminals (U1, V1, W1). These connect to a three-phase bridge rectifier (large diodes). Next to the rectifier, look for a and a charging resistor . When power is first applied, the relay is open; current flows through the resistor to slowly charge the DC link capacitors. Once voltage reaches ~80%, the relay closes. Failure point: Worn relay contacts cause "DC link overvoltage" errors. siemens bsm b3 schematic
If this section fails, the high-side IGBTs will never turn on. When integrating the BSM B3 into a control