An Evaluation Method of Power Loss in Resonant DC Link Inverters.

Abstract

Resonant DC link inverters, which can realize high switching frequency power conversion without switching loss in principle, have been proposed and investigated. In such inverters, power loss is produced in the resonant circuit though power loss in the main circuit is reduced by the amount of the switching loss Therefore, an evaluation method of the total power loss should be established from the view point of efficiency.In this paper, first we summarize the circuit operation and the control method of the resonant DC link inverter. Based on this, the expressions for various power losses produced both in the inverter main circuit and in the resonant circuit are derived. In this derivation, since the turn-on signal for an inverter arm is assumed to be determined only by comparison of the actual output current and its reference, a concept of probability is introduced for the turn-on signal of each inverter arm.As an investigation of the resonant reactor, which affects the total power loss significantly, two types of reactor are constructed and the frequency characteristics of their resistances are clarified experimentally.To confirm the validity of the expressions for losses derived in this paper, a comparison of the calculated and measured total losses is made for an experimental system.