A COST-EFFECTIVE BUS-CURRENT DETECTION TECHNIQUE FOR CURRENT CONTROL AND FAULT DIAGNOSIS OF POWER DIODES IN SRM DRIVES

Abstract

This paper investigates a simple and cost-effective phase current measurement technique for a three-phase switched reluctance motor (SRM), considering its independent phase current control and fault diagnosis of power converter. Unlike conventional current measurement methods, only two current sensors are utilized in such a way that one is installed in the upper bus, and the other is placed in the lower dc-bus to measure the bus currents. In order to extract the phase currents from the measured bus currents, switching functions are rearranged such that during single active region the upper switches chop, while the lower switches remain closed during the phase turn-on region. During commutation region, the upper switches of the incoming phase will remain closed, while the lower switches will perform the chopping function. However, the outgoing phase will observe the same switching function as that of single active region. Furthermore, utilizing the same two sensors without additional devices, the typical open-and short-circuit faults of power diodes are analyzed. Thorough simulations are carried out on a three-phase 12/8 SRM to validate the effectiveness of the proposed technique.