Pre-Charge Components

Pre-charge components control voltage and current applied to the HV system. The initial application of current or in-rush of current, could damage the HV system if not controlled. To control the current application, a large resister is used when the HV system is initially powered up.

The pre-charge components consist of the pre-charge resister, a pre-charge contactor and the required wiring to connect the components. The negative contactor is used during the pre-charge routine.

To perform the pre-charge routine, the BPCM commands the pre-charge contactor and the negative contactor to close. The pre-charge resistor is in series on the circuit with the pre-charge contactor so this controls the power applied to the HV system.

After the pre-charge and negative contactors close and apply partial voltage to the HV system, the BPCM commands the positive contactor to close. This creates a circuit with very little resistance compared to the pre-charge circuit. After the positive contactor has closed, the BPCM opens the pre-charge contactor. The HV system is now fully enabled and ready for operation.