EV-relay performance analysis of reverse surge protection devices

Electric vehicle (EV, HEV, PHEV, FCEV) needs to use high voltage relay. The function is system protection from over current and short circuit by safety switch. The mechanism is that the electric current conduct on coil and generates magnetic field. It makes moving core and fixed core become a magnetic. After that, both of them pull each other by magnetic force. Finally, Relay switch from off to on positon. At the same time, this magnetic field makes reverse current. Because reverse current can damage to circuit, it need to use surge protector at coil side to protect from reverse current. Surge protectors are Varistor and Zener Diode+Diode. Characteristics are different according to use each Diode. From this thesis, LSIS wants to find the different characteristics according to use of each surge protector.