Position Sensors Fault Tolerant Control System in BLDC Motors

Developing of fault tolerant control systems (FTCS’s) for permanent magnet Brushless DC (BLDC) motor drives to diagnose and handle various faults have been of the research concentrations in the last decade. In this paper a novel fault diagnosis algorithm for position sensors (Hall Effect sensors) failure of the BLDC motor is presented. Fault detection and identification of Hall Effect sensors are based on sensors signals and Discrete Fourier Transform (DFT) analysis of the BLDC motor line voltages in the proposed fault diagnosis system. BLDC motor behaviour is analysed under various Hall Effect sensor faults through a validated simulation model. An expert system is developed to diagnose Hall Effect sensors faults in the BLDC motor by analysing the simulation results under different fault conditions. Correct performance of the proposed fault diagnosis system is proven through experimental data analysis. A simple technique is discussed to generate the commutation signal of the faulty position sensor and maintain operation of the BLDC motor in post-fault condition. The proposed fault tolerant control system is simple, does not need excessive computations and can be executed with the main control program of the BLDC motor on a single chip micro-controller.