Sensorless Control Technique Of PMSM Based On High Frequency Signal Injection Method

Permanent magnet synchronous motor(PMSM)is popular in the filed of high performance AC drive system,for advantages such as the small volume,high efficiency and reliability,etc.Due to the application limitations of position sensor in some special occasions,sensorless control technology arises at the historic moment and is favored by many scholars,and become a hot research area of ac motor drive domain in recent years.On the basis of research status and existing problems of PMSM sensorless control technology,sensorless control method of interior permanent magnet synchronous motor(IPMSM)for zero and low-speed operation is deeply studied,and attempts to improve the control precision of sensorless system and dynamic response speed.On the basis of coordinate transformation theory,three-phase original mathematical model of IPMSM is simplified and two phase model is established in two-phase vertical coordinate system.Based on vector control strategy,0di(28)current control and the voltage space vector modulation method are applied to build simulation model,IPMSM vector control algorithm is validated.Based on establishing high frequency mathematical model of IPMSM,the basic principle and implementation process of rotor position estimation is analyzed when high frequency sinusoidal voltage signal is injected in two-phase stationary frame.Research is mainly focused on the important error source that effects position estimation precision: inverter nonlinear factors.For each error nonlinear factor modeling error voltage,total error voltage expression is obtained.When switch state of bridge arm upper and lower power device is changed,charging-discharging process of parasitic capacitance of upper and lower IGBT is analyzed emphatically,the function relational expression between turn off delay time and current value is acquired.The square wave voltage error model is employed to feed-forward correct reference voltage in real-time,and the estimation precision of the rotor position is improved.Sensorless control method based on high frequency square wave voltage signal injection is studied to simplify signal processing and enhance the bandwidth of control system.Inductance matrix contains rotor position information,thus rotor position angle can be calculated through matrix operation after injecting high frequency rotating square wave,high frequency signal envelopes need to beextracted during implementation process,and the response speed of the system is affected.Basic principle of estimation position angle based on pulsating square-wave is analyzed,the signal processing method of acquisition high frequency current by arithmetic operation and without filter is proposed.As a result of higher frequency of injection signal and no filter in signal processing,the system bandwidth is greatly enhanced.Mixed signal injection method including square wave and pulse voltage is applied to detect the rotor initial position angle.Experimental platform of PMSM sensorless vector control system is built.IGBT turn-off characteristics is tested through the double pulse experiment,and the effectiveness of inverter nonlinearity factors compensation scheme is confirmed.Sensorless control experiment based on pulsating high frequency square wave signal injection method is completed and the control performance of the system is verified.