A Novel Phase Loss Detection Method for Low-Cost Motor Drives

This article proposes a novel method for detection of open-phase faults, which was specifically designed for usage in low-cost motor drives. The proposed algorithm uses analysis of current signals to detect the failure and it was developed for usage with conventional configuration of motor drives, where phase currents are measured with the shunt sensors placed in motor phases, or dc-link and which signals are corrupted with a noise. The author discusses the specifics of inverter hardware design for low-cost applications and explains why the conventional techniques are not applicable. After that a new method capable of operating at high noise to signal ratio is proposed and implemented. The experimental results verified feasibility of the developed technique and demonstrated its reliable operation under different load conditions. In order to perform comparative analysis, several conventional algorithms were implemented and their performance was compared to the performance of the proposed method. After experimental verification, this algorithm was included into the existing control scheme of commercial permanent magnet synchronous motors, as a part of the safety module. The modified motor drive successfully passed standardization according to UL 60730 safety standards and was put into mass production.