From the perspective of system function security, each possible risk needs to be configured with corresponding security technology to monitor the risk to reduce the probability of occurrence. From this level, high-voltage interlocking, as a safety measure for the safety of electric vehicle high-voltage systems, is used in circuit design.
One of the risk points of the electric vehicle high-voltage system is the sudden power failure and the car loses power. There are several reasons why the car may lose power, one of which is that the high-voltage circuit is automatically released. The high-voltage interlock can detect such signs and provide alarm information to the vehicle controller before the high-voltage power failure, and reserve the time for the vehicle system to take countermeasures.
Another risk point of electric vehicles is human error operation, which manually disconnects the high voltage connection point during system operation. If no high-voltage interlock design exists, at the moment of disconnection, the entire loop voltage is applied across the breakpoint, which is very dangerous for high-voltage connectors such as those that do not have the breaking capability. Voltage breakdown air pulls arc between two devices. The time is short, but it can be high and can cause damage to people and equipment around the breakpoint.
There are several different statements about the specific purpose of high-voltage interlocking. Some people believe that high-voltage interlocking mainly plays a role before the vehicle is powered on. When the circuit is detected to be incomplete, the system cannot be powered on to avoid accidents caused by problems such as virtual connection. Others believe that the high-voltage interlock is mainly in the collision. The electric function plays a role, and the collision signal is powered off by triggering the high voltage interlock signal. However, in the case of a critical situation after a collision, the step of performing a power failure should be as small as possible, and the collision signal is directly transmitted to the VCU, which is logically more reasonable.