Research On Loss Measurement And Calculation Of Filter Inductors In PWM Inverters

Magnetic components, which play the role of transmitting energy, storing energy, filtering, insulating, etc, are very important in the field of power electronics. With the demand for higher power density, the demand for better magnetic components is also increasing. So it’s really important to do research on the loss measurement, loss calculation and optimum design.This paper focuses on the loss measurement and loss calculation of filter inductors in PWM inverters. A platform for inductor loss measurement and two novel core loss calculation methods are proposed. Also an optimum design method for filter inductors is proposed.Firstly, a platform of inductor loss measurement is proposed, which has many good characteristics like high accuracy, high bandwidth, symmetrical structure, etc. With the coaxial resistor and two normal voltage probes, it overcomes two difficulty points which are 90 degree phase difference between inductor current and voltage and the variable duty ratios and variable DC bias of inductor current.Secondly, based on existing methods of core loss calculation, two more are proposed. One is called the double-envelope method, which is the improvement of loss map method and has good performance on accuracy. Another one is a modified Steinmetz method, which is very useful. Also a copper loss calculation method for Litz wire windings is presented.Finally, core loss and total loss of four different inductors, which are made of Fe-Si, Fe-Si-Al, Fe-Ni and amorphous respectively, are measured. According to the test results, Fe-Si has the best cost performance. An optimum design method is also proposed to minimize the Fe-Si inductor loss.The proposed inductor loss measurement platform has very good performance on accuracy and is easy and practical to use. The summary of modeling methods and optimum design methods are of certain importance and value. It’s hoped that this paper can provide some proposals to engineers.