Sensorless Control Of Five-Phase Permanent Magnet Motor By Injecting High-Frequency Square-Wave Into Third Harmonic Space

The interior permanent magnet synchronous motor(IPMSM)has been widely applied in the field of electric vehicles on account of large torque density,wide speed range and high power density.Compared with traditional three-phase motors,multi-phase motors have superior torque performance and fault tolerance in the drive control system.However,the use of mechanical position sensors will increase the cost and reduce the reliability of the control system.Therefore,it is necessary to adopt the sensorless control technology.In this paper,a five-phase interior permanent magnet motor is taken as the research object,and considering the shortcomings of the traditional sensorless control algorithms,a new sensorless control strategy has been proposed by injecting a high-frequency square-wave voltage signal into the third harmonic space of the prototype.While realizing the sensorless operation of the motor control system,the estimation accuracy of the rotor position is effectively improved,and the torque ripple is reduced at the same time.The main contents of this paper are as follows:(1)The mathematical model of five-phase interior permanent magnet synchronous motor are introduced,including the mathematical model of five-phase IPMSM in the static reference coordinate system and the synchronous rotating coordinate system.At the same time,the vector control strategy of the five-phase permanent magnet synchronous motor is introduced,which is valuable for introducing the sensorless control method.(2)Based on the traditional high-frequency signal injection methods,the low-speed sensorless control algorithms which are commonly used in the fundamental space of five-phase permanent magnet synchronous motors are introduced,including rotating high-frequency sinusoidal signal injection method and pulsating high-frequency sinusoidal signal injection method.The theoretical analysis and formula derivation are also conducted.At the same time,the characteristics,range of application and existing disadvantages of these two traditional control methods are pointed out.(3)A new sensorless control strategy has been proposed for five-phase permanent magnet motor drives based on high-frequency signal injection.A pulsating high-frequency square-wave voltage signal is injected into the third harmonic space of the five-phase motor,and the high-frequency currents in the stationary coordinate system are used to estimate the rotor position,which can combine the advantages of the rotating injection methods and the pulsating injection methods,and simplify the system structure.In addition,this method removes the low-pass filter during signal processing,which can greatly improve the system's dynamic performance,the position estimation accuracy,and the output torque ripple.Finally,the simulation results verify the correctness and feasibility of the proposed method.(4)Taking a five-phase interior permanent magnet synchronous motor as the controlled object,an experimental test platform for its drive control system is built based on dSPACE,and the hardware and software parts of the drive system are designed and tested.Finally,experiments are carried out on the platform to verify the practicability and effectiveness of the high-frequency square-wave voltage injection(HF-SVI)algorithm proposed in this research.