An Iron Loss Estimation Method Based on Dual Current-Ripple Envelopes for Three-Phase Two-Level Grid-Connected Converters

Abstract

An accurate iron loss estimation is necessary before manufacturing the filter inductors of the three-phase grid-connected converters. Besides the loss characteristics of the magnetic core, obtaining an accurate current flowing through the inductor is also very important in the iron loss estimation. In three-phase grid-connected converters, there are two current ripple periods with different magnitudes in one switching period, both of which can generate the iron loss in the converter. In this paper, a dual current-ripple envelopes (DCRE) method is proposed to accurately outline the two current ripples in each switching period. A novel iron loss estimation method is further presented based on the DCRE and the existing iron loss characteristics. Adopting the DCRE method, the influence of pulse width modulation (PWM) schemes, voltage levels, and the amplitude of output current, can be easily evaluated, which provides a satisfactory guidance to the design of the inductor. The effectiveness of the proposed DCRE and iron loss estimation method is verified by the numerical simulation and the experimental test on a three-phase grid-connected converter.

Keywords

• Iron loss estimation
• current ripple
• pulse width modulation (PWM)
• three-phase converters