What is a precharge circuit?

A precharge circuit limits that inrush current, without limiting the operating current. Typical precharge circuit. In the typical precharge circuit, the precharge resistor is on the positive terminal of the battery, though it could just as easily be on the negative terminal.

How can a pre-charge resistor help a battery management system?

By incorporating a pre-charge resistor and forming a pre-charge loop in the battery management system of electric vehicles, the voltage stress on components in the control system can be greatly reduced, the impact current in the circuit can be lowered, so the damage to relays can be prevented, ensuring the safe use of the power battery.

What is a pre-charge state in a HV battery?

The HV battery is disconnected from the load at both terminals and the DC link capacitor remains discharged. Pre-charging introduces a new state in the system, which we will call the pre-charge state. In the pre-charge state, the pre-charge contactor and the HV negative contactor are closed as shown in Figure 2.

When should a battery be pre-charged?

In general, the specific concerns that speak to the need for pre-charge include: When a fuse is likely to blow due to current inrush. When contactors are likely to be damaged by current inrush. When battery cells aren’t rated to handle the inrush current. When capacitors are likely to be damaged by inrush current.

Why do electric vehicles need a power battery system?

The power battery system, which serves as the important energy source for electric vehicles, plays a crucial role in the safety of the vehicle itself. During the charging process, excessive charging current can cause significant impact on relays and rectifier devices.

Does a precharge relay need to be rated for full battery voltage?

The precharge relay needs to be rated for the full battery voltage, because, when the system is off, the full battery voltage appears across its contacts.