Shock surge suppressor thermistor

Once the rated power exceeds 500W, the shortcomings of passive circuit solutions become very obvious. If the ICL is always in series with the load, the power loss it introduces can be very large. The higher the rated power of the device, the longer the typical working time, and the more obvious the accompanying power loss. Assuming that the power loss of NTCICL accounts for one percent of the total power of the device and the efficiency of the power supply is twenty-nine percent, then the total loss of approximately 12.5% is caused by NTC.

Active Inrush Current Control Therefore, for higher power levels, the standard practice is to use a relay or thyristor bypass ICL once the peak surge current has subsided. Depending on the application requirements, the active inrush current control circuit can use power resistors, NTC thermistors or PTC thermistors as ICL components.

For example, PTC thermistors are often used in plug-in vehicle chargers (OBCs) for hybrid or electric vehicles, which typically have a power rating of several kilowatts. While the benefits of active inrush current control are significant for rated powers greater than 500 W, this approach may also be necessary to improve the performance of lower power level applications. Although active inrush current control system cost is slightly higher, it can reduce power loss for lower power ratings applications, and can use relatively inexpensive switches and semiconductor devices with lower ratings.