Coaxial High Voltage Connector Through Holes Straight Plastic 150A 6mm 2 Pin Orange Socket

High voltage interlock connector in BMS

The high-voltage interlock function is also an important function on the BMS, and other high-voltage controllers will also have this function, such as VCU, etc.; its function is to detect the connection status of the High Voltage Interlock Connector in the high-voltage circuit and identify the high-voltage connector is not connected Or accidental disconnection failure;

As shown in the figure below, the loop of the red line in the figure is the high-voltage interlocking loop, which connects all the relevant high-voltage connectors in the system in series and detects their connection status at the same time.

 

High Voltage Interlock Loop

High voltage interlock connector

The realization of HVIL firstly depends on the structure of the connector itself. The high voltage connector integrates the HVIL interface internally. As shown in the figure below, in addition to its own high-voltage and high-current interface, the high-voltage connector also integrates an HVIL interface; the principle is very simple. The HVIL interface has two PIN pins. When the high-voltage connector is plugged in, the two PINs become short-circuited. ; When the high-voltage connector is disconnected, these two PIN pins are open. The HVIL function is realized by detecting the on-off of these two PIN pins.

HVIL connector

HVIL connector

Similarly, the high-voltage maintenance switch (MSD) also integrates the HVIL interface, as shown in the figure below.

There is a time difference between the HVIL interface in the high-voltage connector and the high-voltage high-current interface when it is inserted or unplugged, as shown in the figure below; when the connector is inserted, the high-voltage terminal contacts first, and the HVIL terminal contacts later, the time difference is Δt1; When the device is pulled out, the HVIL terminal is disconnected first, and the high-voltage terminal is disconnected afterwards. The time difference is Δt2; in this way, the HVIL terminal can ensure that the high-voltage terminal has been reliably connected or the accidental disconnection can be predicted in advance.

high-voltage maintenance

high-voltage maintenance

The above two time differences are generally related to the speed of insertion or removal. I have probably tested it before. Δt1 is about 1s, and Δt2 is about 100ms. The time is not very accurate, but the magnitude is about the same.

Next, a brief introduction to the HVIL detection circuit is generally divided into two types, the DC source scheme and the PWM scheme. As shown in the figure below, the left picture is a simplified diagram of the DC source scheme, and the right picture is a simplified diagram of the PWM scheme. In the left picture, an external DC source is applied to the entire HVIL loop, and the high-voltage connector state is diagnosed by detecting the voltage at V1\V2; in the same way, in the right picture, a controllable switch is introduced, the same Still detect the voltage at V1\V2, but by controlling the switch, two sets of values can be obtained to identify more states;

high-voltage maintenance

high-voltage maintenance

The actual HVIL detection circuit is more complicated. First, determine the type of fault to be detected, and then design the detection circuit according to the type of fault; the types of faults include open circuit, short circuit to ground, short circuit to power, and larger loop impedance.

The high-voltage interlock diagnosis is an important safety mechanism that falls into the safety goal of the BMS. Once a fault is diagnosed, the BMS must enter a safe state. Among them, the whole vehicle scene needs to be subdivided. The safety status is completely different in different scenes; for example, the charging scene, the driving scene, and the startup scene.

to sum up:

This article briefly introduces the concept of HVIL. In most cases, the HVIL circuit is a system circuit. It traverses all the main high-voltage interfaces, and the detection range is defined by the OEM. The difficulty of the HVIL function lies in the processing strategy after the failure is found, which is also the core.

0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *