Online Inverter Fault Diagnosis of Buck-Converter BLDC Motor Combinations

Brushless dc (BLDC) motors are commonly used in space application for its simplicity and high reliability. The fault-tolerant control (FTC) of the motor is important for its continuous operating capacity even under the faulty situation. The fault diagnosis should be achieved in advance in order to implement the FTC strategy. This paper proposes an online model-based inverter fault diagnosis method for three-phase full bridge inverter with buck dc-dc converter based on the high-speed BLDC motor with low inductance and nonideal back electromotive force in a magnetically suspended control moment gyro. The method can detect and identify both open-circuit and short-circuit damages of single switch in buck converter or three-phase full bridge. Also, protective measures are proposed to isolate the fault and avoid the secondary fault. Both simulation and experimental results are taken out to prove the validity and effectiveness of the proposed fault diagnosis method.