Study Of Position-sensorless Control Technique For A Dual-winding Fault Tolerant Permanent Magnet Notor

The permanent magnet fault-tolerant motor(FTPMM)have high fault-tolerant performance and it can be widely used in the field of high demands on reliability of the propulsion system like aerospace,ship transportation and medicine.Compared to the single FTPMM control system and redundancy FTPMM,the dual-winding FTPMMs are more reliable,less costly and can improve the space utilization of the system.Now the position-sensorless control technology has been successfully applied in the control of the permanent magnet synchronous motor(PMSM).But there are many theoretical and engineering problems to be solved in the application of FTPMM drive system because of its particularity in structures and control strategies.Therefore,the fault-tolerant control strategies and position-sensorless control technology for a dual-winding FTPMM are studied.1.The vector control technology for a dual-winding FTPMM is analyzed.Thespace vector pulse width modulation(SVPWM)control and current hysteresis band pulse width modulation(CHBPWM)control are compared by simulation and experiment.The SVPWM control has small torque and speed ripples and low harmonic content,but the calculation is relatively complex,especially the time calculation of the voltage vector under short circuit fault condition.The CHBPWM control is relatively simple and is characteristic of fast speed response and good robustness.Therefore,the CHBPWM control strategy is selected.2.The fault-tolerant control strategies are studied.The improved constant magnetomotive force(MMF)fault-tolerant control strategy is proposed to keep the MMF circular trajectory and unchanged size before and after motor failures.The current fault-tolerant control strategy is proposed to keep the torque unchanged before and after motor failures by compensating and distributing currents.By comparing the existing doubling corresponding phase current fault-tolerant control,optimal torque control and improved constant magnetomotive force(MMF)fault-tolerant control,current vector fault-tolerant control,the torque ripples,copper loss and computational complexity under open-circuit and short-circuit faulty conditions are elaborated and simulated in Matlab/Simulink.The results indicate that the current vector fault-tolerant control strategy is characteristic of low torque ripples,small copper loss,simple calculation and it can be used in any combination faults.3.For the position-sensorless control,the algorithm applicable to the FTPMM at medium speed is put forward combined with the variable structure control(VSC),model reference adaptive control(MRAC),VSC-MRAC.The VSC replaces the proportional-integral(PI)controller in the traditional MRAC to improve the accuracy and the function of Sigmoid replaces the traditional Sign function to reduce the chatterings.In this way,the advantages of two control algorithms are integrated;the speed observation is more stable;the system chatterings are reduced,and the dependence of the control precision on the motor parameters is reduced.At low speed,the improved pulse high-frequency current injection method based on generalized second order integrator(SOGI)is proposed.The convergence of rotor position error function is not affected by the impedance changes,and the system stability and dynamic performance is improved.And the composite control combines the VSC-MRAC control at medium speed and pulse high-frequency current injection method at low speed.Two control algorithms are smoothly switched and the rotor position estimation of FTPMM at all speed range is realized.4.To estimate the rotor position under faulty conditions,the current fault-tolerant control strategy is applied in position-sonsorless control.Under faulty conditions,the d-q axis currents related to rotor position estimation can keep the same under healthy and faulty conditions;therefore the position estimation algorithms can be applicable under faulty conditions.The correctness and feasibility of the rotor position estimation algorithm under different speeds is verified by Matlab/Simulink under healthy,open-circuit faulty and short-circuit faulty conditions.5.The software programmes based on position-sensorless control algorithm and fault-tolerant control algorithm are designed and debugged on the experimental setup of dual-winding FTPMM control system based on TMS320F28335 DSP.On the experimental setup,the contrast experiment of SVPWM and CHBPWM under healthy condition and the position-sensorless control experiment under healthy and faulty conditions are engaged.The experimental results show that the rotor position can be accurately estimated by the rotor position estimation algorithm based on VSC-MRAC under healthy and open-circuit faulty conditions.