IPMSM Sensorless Low Speed Control Strategy Based On Noise Suppression

Permanent magnet synchronous motor(PMSM)has the advantages of high power density,high torque density,small size and high efficiency.The most widely used control technology of permanent magnet synchronous motor is vector control technology.The key to realize this technique is to obtain rotor position information.However,the traditional position sensor is usually used to obtain the rotor position information,which increases the cost and volume of the motor and reduces the reliability of the system.Therefore,the high reliability and low cost position-free sensor technology has gradually become the mainstream.The inherent convex polarity of the IPMSM structure of the built-in permanent magnet synchronous motor is more suitable for the control situation and becomes the main research object in this paper.It is difficult to apply the observation method based on the reverse electromotive force because the reverse electromotive force is small when the motor is running at low speed.When PMSM is running at low speed(including zero speed),the high-frequency injection method is most often used.The traditional high frequency injection method must use various filters in the process of current loop feedback and position error extraction,which makes the system have extra delay.Therefore put forward the two injection methods,is able to offset the inverter inherent nonlinear error and the purpose of eliminating filter,finally chose the improved without digital filter of square wave permanent magnet synchronous motor injection method,the method is perfect to solve the problems of both,and do not need to separate the vector control and the injection cycle,guarantee the stability of the system as a whole.In addition,as the signals used in the high frequency injection method are all fixed amplitude and frequency signals,the current power spectrum density is too concentrated,which causes the problems of high frequency noise and electromagnetic compatibility,and affects the use of surrounding electronic equipment and noise environment pollution.In order to suppress the noise and improve the runningenvironment of the motor,the square wave injection method with random frequency is proposed,and the signal processing mode of the method is discussed in detail to ensure the other performance of the system while reducing the noise.The initial position detection of rotor is an important part of sensorless control,so it is necessary to detect this method.Then a suitable observer is selected to extract the location information.At last,the proposed strategy of 1.5kw sensorless vector control experiment platform degree is built,and a number of experiments are carried out,which successfully verifies the feasibility and superiority of the proposed strategy.