Position sensorless control of five-phase BLDC motor under single-phase open circuit fault

To increase the fault tolerant capability and reliability of the driving system for five-phase motor, the position sensorless control of five-phase preferment magnet BLDC(BrushLess DC) motor under single-phase open circuit fault is investigated. A novel decoupled fault tolerant motor model is introduced, and the field oriented control and carrier pulse width modulation under single-phase open circuit fault are realized. A sliding mode observer is used to estimate the fundamental back-EMF(ElectroMotive Force) of the five-phase motor. However, the 3rd harmonic winding and nonlinearity of electric inverter result in chattering harmonic in estimated back-EMF under the open circuit fault mode. To tackle this problem, an improved complex coefficient filter is proposed, which can replace the first-order low-pass filter in smoothing back-EMF without phase and magnitude distortions, and hereby can improve the accuracy of estimated position and enhance motor dynamic characteristics under sensorless control. The position sensorless control method under single- phase open circuit fault is performed on the experimental platform, and the effectiveness of the proposed control method is confirmed by experimental results.