Sliding Mode Control of a Switched Reluctance Motor Drive with Four-Switch Bi-Directional DC-DC Converter for Torque Ripple Minimization

In this paper, a method to drive switched reluctance motors (SRM) with a modular four-switch bi-directional DC-DC converter and an H-bridge is proposed. The DC-DC converter operates as a buck or a boost converter with constant frequency to control each phase current while the H-bridge inverter switches only twice in a period to adjust the polarity of the phase voltage. Sliding mode control is designed to have fast and robust current control in the DC-DC converter. The sliding surface equation which is derived for all operation modes including buck and boost modes in motoring and regenerating conditions is defined with the estimated inductor current. The proposed drive system eliminates the bulk DC-capacitors and allows one to adjust the bus voltage individually for all phases. Moreover, the proposed system topology works with only one high-frequency switching device in the DC-DC conversion stage rather than two in conventional drives which provides a simpler current control and reduced switching losses.