Study Of PMSM Position Sensorless Control And High-Performance Operation Strategy

Permanent magnet synchronous motors(PMSMs)have the advantages of,for example,high power density,excellent speed regulating performance and flexible configurations,thus,have been widely used in applications of traction drive,position servo,efficient power output,etc.The high performance control of PMSM demands the information of rotor position or speed,whilst one of the research topics is to obtain the high performance control of PMSM without using rotor position or speed sensors.Such sensorless control is to obtain the rotor position or speed information using the measurements of voltage and/or current.Sensorless control has the advantages of low hardwarecost,low system volume,and high reliability.Therefore,sensorless control is the subject that has significant practical values,and deserves deep investigations.In this dissertation,developments of PMSM control will be introduced briefly,and literatures of PMSM control,especially the sensorless control,by both domestic and overseas researchers will be reviewed.Moreover,focuses and difficulties of the sensorless control will be summarized.Based on the above investigation,a series of work for PMSM sensorless control in fanlike system will be presented in the dissertation,which can be summarized as follows:Firstly,the principles of four high-frequency injection methods are given,and the principles of some rotor magnetic polarity identification methods are also introduced and compared,based on which,two novel rotor polarity identification schemes are proposed.The proposed polarity iden-tification schemes are called AC current excitation method and rotary acceleration based method,respectively.Compared to the existing methods,the AC current excitation method has the advan-tage of higher reliability,whilst the rotary acceleration based method is a brand new rotor polarity identification method based on the speed model.Based on the proposed methods,a novel robust initial rotor position estimation scheme is realized.Then,the principle of open-loop flux observer is derived,and a new kind of high-frequency injection method,named independent rotary reference frame pulsating high-frequency injection,is proposed.The method is applied along with the open-loop flux observer to form a combined wide speed range position estimation scheme.Compared to the conventional pulsating high-frequency injection method,the proposed method has the advantage of independent position estimation,thus has wider scope of applications.Moreover,a virtual flux linkage-based switching strategy between the high-frequency injection method and the flux observer method is proposed.Compared to the traditional speed-based switching strategy,the virtual flux linkage-based strategy is more robust and versatile.Subsequently,position estimation methods which are applicable to high initial speed are an-alyzed and summarized.Based on the existing work,a novel current-amplitude-regulated zero voltage vector method is proposed.The proposed method has the ability of position estimation at high initial rotary speed,and meanwhile makes the current small enough and under control.Fur-thermore,a smooth switching algorithm between the proposed current-amplitude-regulated method and the zero current vector regulated method is proposed.The proposed switching algorithm can realize a combined high initial speed rotor position estimation scheme.After that,usages of moving average(MA)in the motor control as well as in the performance optimization are summarized and analyzed.In order to compensate the lag of the MA,a new parallel compensation MA scheme is proposed.In order to make the MA speed adaptive,a novel fixed-sampling-interval-fixed-depth MA(FTFDMA)is also proposed.Based on the FTFDMA,two performance optimization strategies,namely average speed control and real-time electrical parameter identification are implemented.The average speed control performs as a decoupling stage between the position estimation and the speed regulation,which can lower the vibration for the fan system in this dissertation.The real-time electrical parameter identification is beneficial to the motor controller to realize the running state regulation or the real-time fault detection,and consequently helpful to improve the operating performance and the system reliability.Therefore,based on the work stated above,comprehensive strategies of rotor position esti-mation and high performance operation for the PMSM system are achieved.Robust start-up per-formance of the sensorless PMSM at arbitrary initial speed as well as the wide speed range dual directions operation are realized.The contents of this dissertation are based on the fanlike system,however,the research results have reference significance to other types of motor applications.