Novel three-phase SMR converter with new bilateral switch circuits consisting of IGBT

This paper describes the SMR (switch mode rectifier) having a quite new circuit configuration, which has been developed by the authors and given the name “DC-clamped type SMR” (DCC-SMR). The DCC-SMR is unique in that no bilateral switching device is used in the frequency conversion circuit. Therefore, the authors have used a DC snubber circuit for the switching device of the DCC-SMR. This DC snubber circuit features a very simple structure consisting only of a capacitor with no need for a discharge resistance or a complicated snubber energy regenerative circuit. This is because snubber energy is regenerated on the primary side of the HF (high frequency) transformer by the main switch. Furthermore, an innovative method has been applied for the magnetic saturation-preventive control of the HF transformer. The authors carried out the operational checks on the main circuit and snubber circuit of DCC-SMR as well as on the magnetic saturation-preventive control through experiment, and confirmed a satisfactory result. The authors manufactured an industrial DC power supply prototype of the DCC-SMR system having a DC output of 100 kW (100 V, 1000 A), with which an input/output conversion efficiency of 91.6%, an input power factor of 0.99 and an input current total harmonics distortion factor of 4.6% were obtained