Research On Fault Of Voltage Inverter For Brushless DC Motor System

The brushless DC motor is a kind of products of mechatronics technology which uses electronic commutation technology ranther than commutator-brush.It,as the same as the general DC motor,has many advantages,such as the high efficiency, large starting torque, wide speed regulation range and the linear mechanical properties and so on. Furthermore, like the AC motor, it's structure is simple and its maintenance is easy.Therefore, it is widely used in industrial, commercial, aviation and military fields.However, with the fragility and the control complexity, the inverter prones to be the weak part in the system which reliability has not been fully resolved.Once the inverter broke down, the entire drive system will lose its ability to work normally, which will affect the normal production process, and,may even cause a catastrophic accident. Thus, studying the failure modes of the inverter has important theoretical significance for the fault diagnosis technology and fault-tolerant technology of electrical system.Firstly, in the paper, for the brushless DC motor, its mathematical model and running principle are analysed. On this basis, a simulation study of operating characteristics is done to get the dynamic performance of a brushless DC motor when it work normally.Then several typical faults of the voltage inverter are analysed. And, especially, the features of the switch tube's open circuit fault and short circuit fault are deeply studied. With the simulation, the inverter circuit topology with a fault or without one, as well as the output characteristics of the system such as the electrical voltage, current, output torque, speed and output power and so on, are studied.Finally, the output characteristics of the system are obtained, which lay the foundation for the next step to analyse integratively the inverter faults and design the reorganization of the inverter.Based on the above theoretical studies, a test platform with the application specific integrated circuits (ASIC), MC33035 and MC33039, is set up. By setting the typical failure modes of the inverter switch tube,To the brushless DC motor switch tube, current values under no-load and the rated load with a fault or not are measured and analysed. This study has guiding significance for the optimization of the protection circuit, the fault diagnosis and the design of the controller with fault-tolerant function.