Multiple Objective Fault Diagnosis And Fault Tolerant Control Of Inverter

With its superior performance, frequency control system is widely used inindustry. However, as a power electronic product, it can have problems or failures.Once inverter occurs fault, it may cause huge economic losses, and even casualties.To improve the reliability of the system is urgent. It is reflected in two aspects: onthe one hand, diagnosing and locating the fault rapidly is convenient for repairing.On the other hand, make the inverter run normally after failure as much as possible.Inverter has many fault types, and speed sensors, current sensors, switches are verycommon. The three kinds of fault types are studied in the paper.Firstly, for the diagosis of multiple IGBTs open circuit fault, this paperproposed two methods of diagnosis. One was based on modified three-phaseaverage current method and the other was based on the modified normalizedthree-phase average current method with Fourier transform. The modifiedthree-phase average current method proposed new algorithm and the paper validatedthe proposed method by mathematical derivation. The modified normalizedthree-phase average current method based on Fourier transform used a newalgorithm and dignosis strategy, which could locate multiple IGBTs open circuitfault correctly under different load. For the method, this paper studied the selectionof threshold and diagnostic procedure by mathematical derivation. The twoproposed methods were proved by Matlab/Simulink simulation.Secondly, the single current sensor vector control was studied. The paperimproved the traditional method by introducing the current error of to theLuenberger observer. The stability of the system was deduced. The new method canoperate in the low and high speed condition. The new method was proved byMatlab/Simulink simulation.Finally, a speed observer based on sliding mode control was proposed. Theobserver was based on the model reference adaptive observer. The expression ofspeed could get by Lyapunov stability formula derivation. Matlab/Simulinksimulation verified the proposed method. The mehod has good anti-interferenceability and accurate observation and does not need to adjust the gain of the complexsystem.According to the research above, an experimental platform was built ondSPACE platform, which had the function of simulation of multiple IGBTs opencircuit fault. Through the experiment, the two diagnosis methods of multiple IGBTsopen circuit and a single currene sensor vector control method were verfied.