Analysis of Passive Boost Power Converter for Three-Phase SR Drive

This paper presents a novel passive boost power converter and its analysis for a three-phase switched reluctance (SR) drive. The proposed simple passive circuit adds three diodes and one capacitor to the front end of a conventional asymmetric converter in order to obtain a high negative bias. Based on this passive power network, the terminal voltage of the converter side is at general dc-link voltage level in parallel mode and is up to a double dc-link voltage level in series mode. As a result, it can suppress the negative torque generation from the tail current and improve the output power. Combining a passive circuit with a three-phase asymmetric converter without phase-current overlap, the phase winding obtains the dc-link voltage in the excitation mode and the negative double dc-link voltage in the demagnetization mode. With the phase-current overlap, the dc-link voltage or the double dc-link voltage is dependent on the overlap current. The operation modes of the proposed converter are analyzed with a three-phase SR motor. The selection of the boost capacitor is considered, and a detailed analysis of current-overlap modes is presented. The compared simulation and experiments are done. The results verify the performance of the proposed converter.