Research On Five-phase Permanent Magnet Synchronous Motor Control System

With the development of power electronic technology,AC drive system is no longer restricted to three-phase power supply,and gradually develops towards five-phase drive control system.Compared with three phase motor,five-phase permanent magnet synchronous motor(PMSM)has the advantages of high reliability,high power density,low torque ripple and strong fault tolerance.Therefore,it is widely applied in the fields of rail transportation,aeronautics and astronautics,medical and health and so on.In motor drive control systems,inverters often fail.When the inverter fails,the voltage and current stress of the power tube will increase.In serious case,the power tube will burn out.Therefore,based on the current normalization method,four common open circuit fault detection methods of inverter are studied in this paper.On the basis of fault detection,the decoupling fault-tolerant control of single-phase open circuit fault of motor is studied to ensure that the motor can run smoothly after failure.The main contents of this thesis are as follows:With the increase of the number of motor phase,there are diverse SVPWM modulation methods for the five-phase PMSM.In this thesis,the operating principle of NTV and NFV is mainly analyzed.The simulation and the experimental results prove that the NFV has the advantages of less harmonic content,high sinusoidal current and fast dynamic response speed.Hence,the modulation method of NFV is adopted as the control strategy for the five-phase PMSM in this thesis.To avoid the deterioration of system performance and equipment damage caused by motor inverter failure,the inverter fault detection is studied in this thesis.The inverter fault detection method based on current normalization is proposed to detect the four fault types of inverters,such as single tube open fault,single phase open fault,adjacent two phase open fault and non adjacent two phase open fault.The research results show that the proposed fault detection method can accurately and quickly diagnose the fault location under the condition of static and dynamic state,which can provide the premise for fault-tolerant control.In the motor control system,the single-phase fault is the common fault type.Thus,the fault-tolerant control strategy of single phase-loss for the five-phase PMSM is investigated in this thesis.The decoupling fault-tolerant control strategy for the single-phase fault is proposed to achieve the smooth operation when the single phase-loss fault occurs and reduce the torque ripple under the motor fault condition.Additionally,the experimental platform is set up to verify the proposed fault-tolerant control strategy.The experimental results show that the proposed method can realize the complete decoupling of motor control when the fault happens.Then,the proposed control strategy can linearly adjust the torque and effectively reduce the complexity of the system.Under the premise of reducing torque ripple,the minimum copper loss of the motor stator winding can be obtained and the efficiency of motor can be improved.