Effective resistor selection method for over current protection when using sense IGBT solution

In the power electronics system, over current protection (OCP) is required to protect power semiconductors such as IGBT, MOSFET and the system. There are several methods for OCP. In this paper, the OCP method by using sense IGBT is introduced and explained. As the operation power is increased, the method using the sense IGBT can reduce the area of the circuit and the switching loss compared to the other methods. When using sense IGBT, a resistor which is called RSC (resistor of sense cell, connected to emitter of sense cell externally) for converting sense IGBT current into voltage should be properly selected to design the appropriate trip current level. However, it is difficult because sense IGBT current changes according to external circuit and operating condition. In this paper, the effective and proper method is introduced to select appropriate RSC value under the variable condition. Experimental and calculation results show an error rate within 5%, so it is verified that the implemented method is appropriate.