Rerearch On Control System Of Three-Phase Open-End Winding Permanent Magnet Synchronous Machine

With the rapid development of electric vehicle technology and wind power generation, open-end winding motor gradually attracts public attention. Compared with the traditional motor, open-end winding motor has the advantages of high power supply in low-voltage level, multi-level phase voltage and fault-tolerant capability. The open-end winding motor control system is always supplied by dual two-level inverters, which is same as the full-bridge topology. The dual inverters topology has two variants which are different in DC bus. The topology with common DC bus has advantages in simpler construction and lower cost compared with the one which has separate DC bus. There is zero sequence current produced by common voltage and harmonic component of back EMF in Dual inverters with common DC bus topology. For open-end winding three-phase PMSM control system based on dual inverters of one common DC bus, a SVPWM method that can eliminate the common voltage produced by two inverters is proposed. Compared with the decoupled SVPWM method, the proposed method is suitable for the common DC bus topology. And the fault-tolerant capacity of this topology is also researched. Without changing the SVPWM method, the motor control system can remain torque output capacity in some degree after single switch failure. This paper focuses on the study of open-end winding three phase PMSM control system based on the dual inverter topology with one common power source, mainly including the mathematical model of the open-end winding three phase PMSM, vector modulation algorithm, fault-tolerant operation and experimental analysis of the motor control system.Firstly, the dual inverter construction is analyzed. The differences between the topology with one DC bus and separated DC bus are discussed. Then the mathematical model of the open-end winding three-phase PMSM under rotating coordinate system is deduced. The equivalent circuit of zero axis is presented Besides, the basic vector control principles of the six-phase motor are briefly introduced.Secondly, the space vector modulation method is proposed for the dual inverter with one common source. The dual inverter system has the same voltage vector output capacity with the three level inverters. The redundancy of voltage vectors and switch states provide more choices to synthesize the reference voltage vector. A simplified PWM method that can omit sector identification and trigonometric calculation is applied when using the proposed method. The simulation results show the efficiency of the proposed method to eliminate the common mode voltage in three phases. And the simulation of the vector control system of open-end winding three phase PMSM is also applied.Thirdly, the fault-tolerant control strategy of open-end winding three phase PMSM with dual inverters is presented. The vector distribution of the dual inverters after single switch failure is analyzed. The operation area is reduced to the inner hexagon when adopting the fault-tolerant control strategy. There is no need to change the other parts of the control system. Then the fault-tolerant operation of the control system is simulated.Finally, the experimental system platform for the open-end winding motor control system is built. Software design includes the DSP programming. The experimental results verify the theoretical analysis and simulation of the control system.