Experimental Study on Effect of Load on Iron Loss of an Electrical Steel Sheet Under PWM Inverter Excitation

This paper investigates the effects of a load on the iron loss of an electrical sheet using a ring specimen with a secondary coil under pulse width modulation inverter excitation. In this experiment, the resistance load is connected to the secondary coil to simulate the motor load. To investigate the iron loss under load, we derive two methods to calculate the iron loss: the current difference method (CDM) and the power difference method (PDM). In the CDM, the iron loss is determined using the differential between the input current from the power amplifier to the specimen and the output current from the specimen to the load and voltage of the B-coil. In the PDM, the iron loss is derived using the differential between the input and output power. The iron loss calculated using the CDM and PDM agrees well when the secondary coil is open circuit, whereas the difference in the iron loss between the CDM and PDM increases as the resistance of the load decreases, especially when the carrier frequency is high.