Abstract
At present, pulse width modulation (PWM) technique is widely applied in motor drive systems. However, it may cause some unexpected effects: Bearing currents, overvoltage, power losses and unwanted noise. In some industrial cases, LC filters are always equipped in motor drive systems to suppress those unexpected effects. In order to improve the reliability and safety of the drive system, fault diagnostic strategies for power switches should be utilized as other drive systems without LC filters. In the literature, some open-switch diagnostic approaches are based on the observers derived from the mathematical models. However, the models are changed by the LC filters. Therefore, the existing approaches, based on the observers are failed, due to the change of the models. This study proposes an open-switch diagnostic method for permanent magnet synchronous motor (PMSM) drive equipped with LC Filter. The novelty of the proposed method is that the model of the LC filter is considered. Therefore, open-switch faults can be detected and located in the drive systems with LC filters. The switching function model of the drive system is analyzed at first. Then a sliding mode observer (SMO) considering the model of the filter is proposed to estimate the filter voltages and other state variables. Consequently, the faults can be detected and located through the residual errors between the expected and estimated filter voltages. This approach features simplicity. Furthermore, any extra sensors are not necessary. Experimental results on a 750-W PMSM drive system with an LC filter proved the feasibility of the proposed method.
Highlights
In recent years, permanent magnet synchronous motors (PMSMs) have been applied in industrial power applications, because it features high efficiency, high power density and simple operation
The purpose of this study is to propose a novel observer-based open-switch diagnostic method for PMSM drive connected with LC filter
This paper proposes a novel sliding mode observer (SMO)-based open-switch diagnostic method for permanent-magnet synchronous motor drive connected with LC filter
Summary
Permanent magnet synchronous motors (PMSMs) have been applied in industrial power applications, because it features high efficiency, high power density and simple operation. Most of the PMSMs are driven by voltage source inverters (VSIs), and pulse width modulation (PWM). Because PWM waves are asymmetric pulses, it may result in bearing currents and overvoltage [1,2,3,4,5,6]. Unwanted power losses and noise may be caused by the harmonics of PWM waves. For low cost and convenient operation, the LC filter has become the most widely used hardware [7]. The LC filter is connected between the power inverter and motor, as illustrated in Energies 2019, 12, 3288; doi:10.3390/en12173288 www.mdpi.com/journal/energies
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