Control method to balance capacitor voltages in split-AC switched reluctance motor drives during startup and at low speeds

This paper proposes a control method to balance capacitor voltages for a four-switch single-stage two phase switched reluctance motor drive with integrated power factor correction. Initial alignment process is necessary for SRM before operation. However, the phase current is unbalanced during that time, which would cause over-voltage issue on DC capacitors as split-AC structure is used. This problem also exists when the motor speed is low, as in startup of electric vehicle. Based on the unified model, an advanced control method is proposed to eliminate the voltage difference between the capacitors. This method does not require any other circuits or components. It also does not affect the performance during normal conditions. Experiments are performed to verify feasibility of the control method.