Why do electric vehicles need High Voltage Interlock Connectors?

High Voltage Inter-lock (HVIL) is a safe design method that uses low-voltage signals to monitor the integrity of high-voltage circuits. Theoretically, the specific volume and high pressure of the low internal pressure monitoring loop is connected first, then disconnected, and the necessary advance is maintained in the middle. The length of time can be determined according to the specific situation of the project. The specific high-voltage interlocking realization form may have different designs for different projects. The monitoring target is electrical interface components such as high-voltage connectors that require manual operation to achieve circuit connection or disconnection.

In the high-voltage circuit of electric vehicles, the electrical components that require HVIL function are mainly high-voltage connectors and manual maintenance switches (MSD). From the perspective of system functional safety, every possible risk needs to be monitored by corresponding safety technical means to reduce the probability of risk occurrence. From this level, high-voltage interlocks are used in circuit design as a safety measure for the safety of high-voltage systems in electric vehicles.

The high-voltage interlocking connector is composed of a plug wrench with a card slot, a secondary lock with a guide slot, and a high-voltage interlocking micro switch.

Principle of high voltage interlock:

There are two factors to consider in the design of high-voltage interlocks. One is how the low-voltage system can fully detect the connection status of each connection position of the entire high-voltage system; the other is how to realize the information transmission action of the low-voltage detection circuit must be ahead of the high-voltage The action of circuit disconnection. Therefore, the principle of high-voltage interlocking needs to proceed from these two aspects, considering the overall circuit design principle and the design principle of the connector itself.

Risks of high-voltage systems in electric vehicles:

1. Sudden power failure, the car loses power. There are several reasons that may cause the car to lose power, one of which is the automatic release of the high-voltage circuit. The high-voltage interlock can detect such signs, and provide alarm information to the vehicle controller before the high-voltage power failure, and reserve time for the vehicle system to take countermeasures.
2. Human misoperation. During system operation, manually disconnect the high-voltage connection point. If there is no high-voltage interlock design, at the moment of disconnection, the entire circuit voltage is applied to both ends of the breakpoint, which is very dangerous for devices such as high-voltage connectors that do not have the ability to break. The voltage breakdown air draws an arc between the two devices. Although the time is short, the energy is high, which may cause injury to personnel and equipment around the breakpoint.

There are several different opinions about the specific purpose of high voltage interlock. Some people believe that the high-voltage interlock mainly plays a role before the vehicle is powered on. If the circuit is detected to be incomplete, the system cannot be powered on to avoid accidents caused by problems such as virtual connections. Others believe that the high-voltage interlock is mainly caused by collisions. Play a role in the electrical process, the collision signal triggers the high-voltage interlock signal to execute the system power-off. However, in a situation that is more critical after a collision, the number of steps to perform power off should be as few as possible. The collision signal is directly transmitted to the VCU, which is logically more reasonable.

The new energy industry (mainly automobiles) has relatively high requirements for the industry application of connectors. The high-voltage interlock structure avoids the phenomenon of arcing during the disconnection of the high-voltage connector, extends the service life of the interlock mechanism, and effectively prevents misoperation The risk of electric shock caused by, to ensure the safety of maintenance.

HVSL series products are a new generation of plastic high-voltage interlock connectors, including high-voltage, high-current, signal and other solutions for high-voltage power wiring harnesses and signal connections for hybrid and electric vehicles. Elecbee can provide a variety of series of product options, 1 core to 3 core, rated current 23A to 250A, anti-touch, HVIL. Single-core or multi-core shielded cables can be used. If you are interested in our products or have any questions, you can contact us at any time and look forward to cooperating with you.

If you want to learn more about high voltage interlock connectors, you can click to read: What do you know about the butt failure of high voltage connector?