company news about Operating principle of EV fuse

        In response to the design requirements of the electric vehicle safety regulations on the over-current disconnecting device of the high-voltage system, in the EV high-voltage electrical architecture, the combination of fuse and contactor is generally used for coordinated protection to achieve over-current disconnection and disconnection of the on-board rechargeable energy storage system and other high-voltage systems.

        Generally speaking, EV will cut off the contactor through overload current detection, while fuse is used for short circuit and large current protection. The ideal protection is that the fuse is triggered as the first one (the fuse has the lowest initial cost of any protection system) and can correctly clear the fault before any other protection element starts to act. The challenge is that the fuse needs to act before the contactor overheats or exceeds its open state, and the entire EV/HEV high-voltage system has multiple circuits, and the branch fuses need to be selectively coordinated.

        a) In order to avoid that the fuse will not break and other components (such as contactors and cables) will be damaged in case of short circuit fault, it is necessary to calculate the I between the fuse in the circuit and its protection object ² t。

        b) Based on the EV/EVP electrical parallel architecture of each system component, there is a certain correlation between vehicle circuits, and ripple current exists between the main drive circuit and other auxiliary system circuits (especially during vehicle acceleration/deceleration). In order to avoid abnormal breaking of fuses caused by ripple current between systems, it is necessary to reasonably design the circuit of each component (such as bus circuit type, capacity, etc.).