In the previous section, we explained what is high-voltage interlock connector. In this chapter, we explain the The working principle and realization of high voltage interlock
1: The working principle and realization of high-voltage interlock
There are two factors to consider in the design of a high-voltage interlock. One is how the low-voltage system can comprehensively 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 system. The action of breaking the circuit. Therefore, the principle of high-voltage interlocking needs to start from these two aspects, considering the overall circuit design principle and the design principle of the connector itself.
All high-voltage connector docking positions are equipped with high-voltage interlock signal loops, but the loop form does not have a necessary connection with the high-voltage loop. That is to say, on high voltage, electrical A and electrical B form a complete circuit. But for high-voltage interlock, it is possible to set a separate interlock signal loop for A and a separate interlock signal loop for B; it is also possible to connect the interlock signals of A and B in series in a loop.
The power battery pack is used as the power source in the high-voltage loop, and the low-voltage loop also needs a power supply for detection, so that the low-voltage signal can be transmitted along the closed low-voltage loop. Once the low-voltage signal is interrupted, it means that one of the high-voltage connectors is loose or falls off. The schematic diagram of the high voltage interlock is as follows. Based on the high-voltage interlock signal loop shown in the picture below, according to the overall strategy, design monitoring points or monitoring loops, which are responsible for transmitting the status of the high-voltage interlock signal loop to the VCU or BMS.
There are two types of high-voltage interlock monitors, one that monitors whether the high-voltage circuit is fully connected, and the other that monitors whether the high-voltage electrical enclosure is in place. The two monitors are used in different high-voltage interlock systems and cannot be mixed.
2: How HVIL connectors work
In the high-voltage circuit of electric vehicles, the electrical components required to have HVIL function are mainly high-voltage connectors. .
The high-voltage interlocking connector is generally realized by a pair of male and female connectors that are inserted into each other, and a pair of high-voltage connectors and a pair of low-voltage connectors are respectively fixed.
In the state of high voltage disconnection, the low voltage circuit is cut off; in the state of high voltage connection, the breakpoint of the low voltage circuit is shorted to form a complete circuit
DC high-voltage connector, the high-voltage loop has two sets of positive and negative male terminals and female terminals. The low-voltage circuit is also composed of two pairs of male and female pins and a housing. On the male head and the female head, the high and low voltage conductive parts are fixed on a shell, and the relative positions are fixed.
To realize that the low voltage is higher than the high voltage, the disconnection information is obtained first, and the connection completion information is obtained later. It is necessary to ensure that the low-voltage loop pin is later than the butt contact time of the high-voltage loop terminal, and the length of the high-voltage terminal and the low-voltage pin can be adjusted. A general statement is that the low-voltage pins are short (or backward), the high-voltage terminals are just in contact, and the low-voltage pins are still some distance away; The terminals are also plugged into place.
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