A novel boost capacitor circuit to enhance the performance of the switched reluctance motor

The most important drawback of the switched reluctance motor (SRM) lies in its low efficiency at high speed. In fact, with a fixed DC source voltage, when the speed rises, the maximum phase current as well as the output power decrease because of the increase of the "motional" EMF. In order to remedy this, we propose to use, in series with the DC supply, a novel boost capacitor circuit for raising the phase voltage. This novel circuit is composed of the combination of a parallel transistor, a diode and a capacitor in series with a bi-directional switch. Thanks to this switch, the capacitor boost voltage is maintained within two values; the maximum one depends on the DC supply voltage and the maximum voltage ensuring a quite safe working of the converter components; the minimum one depends on the speed, the capacitance of the boost capacitor and its maximum voltage. The aim of this paper is to show that with this boost capacitor circuit, the SRM is able to work with a very high efficiency in a wider speed range than the existing boost circuits