Working principle of High-voltage DC relays
The high-voltage direct current relay is mainly composed of components such as the coil, armature, contacts, arc suppression chamber, spring, and housing.
At present, the relays used in electric vehicles need to have the function of load-carrying disconnection. During the process of load cutting, high-temperature and high-pressure arcs are generated, which can cause damage to the contacts of the relay, resulting in contact sticking. In severe cases, it can even cause the relay to explode, seriously endangering the safety of electric vehicles. To reduce the damage caused by the electric arc to the contacts of the relay, the contacts of the on-board high-voltage direct current relay are usually placed in an arc-extinguishing chamber.
In most cases, vacuum, hydrogen gas or other mixed gases are used as insulating media in the arc suppression chamber. Although gases mixed appropriately with hydrogen and other gases do not have as high insulation performance and lower leakage current as vacuum-type or sulfur hexafluoride-type relays, hydrogen gas has reducibility, which can effectively prevent the oxidation of contacts, and its excellent thermal conductivity also helps to reduce the temperature rise of contacts during the arc generation process, thereby protecting the arc suppression chamber. Usually, electromagnetic arc blowing is combined to enhance the arc suppression capability. However, the distribution position of the arc suppression magnetic field in the relay design process varies. In some relays, the high-voltage contacts have positive and negative poles. If the high-voltage positive and negative poles are connected in reverse during use, it will instead reduce the load-breaking capacity of the relay. This is something that needs to be noted during use.
