Characteristics Of Electric Vehicle Fuses

Generally speaking, electric vehicle fuses need to have the following characteristics:

1) DC protection;

2) Can break small short-circuit currents;

3) Can withstand frequent high current shocks:

4) Can withstand unpredictable current loads and hot and cold cycles;

5) Low power consumption, low temperature rise;

6) Meet automotive-grade mechanical strength, vibration and shock requirements; etc.

In the case of normal use of electric vehicle (EV) system, irregular surge current (or large current) will appear in both the main circuit and each branch circuit. 8 to 10 years warranty. This requires that EV fuses must have strong resistance to current impact, and the service life needs to exceed 10 years.

In the event of a short circuit in the EV system, since the short-circuit current that can be released by the power battery itself is not large (according to experience, the current maximum short-circuit current in the EV industry is ≤12kA), if the power of the power battery is not fully charged, it can be released When the power of the short-circuit battery is not full, the short-circuit current that can be released is smaller - according to experience, the minimum short-circuit current is generally 2kA~4kA.

According to the characteristics of EV applications, it is difficult for ordinary industrial protection fuses or semiconductor protection fuses to meet the protection needs of EVs. The main reasons are as follows:

1. aR (semiconductor short-circuit protection) fuse: According to the fuse IEC and UL standards, only when the short-circuit current is above 10In can aR fuse break the fault safely and quickly. At present, the better aR fuses in the fuse industry generally can safely break the current of 5~7In. When the fault current is less than 5In, the fuse cannot guarantee safe breaking. If the aR fuse is directly used for EV protection , there may be problems such as arcing of the fuse terminal, causing the tube body to burn black, or even burn;

2.gR fuse (fuse for semiconductor overload and short circuit protection): According to IEC and UL regulations, the conventional fusing current of gR fuse is 1.6In, the conventional fuse time is 1 hour, and the overload fusing time is much slower than EV protection requirements. If the gR fuse is directly used for EV protection, due to the slow breaking time, the temperature of the line connected to the fuse will be too high, which may cause fire or damage to peripheral devices.