Research On The Control System Of Permanent Magnet Synchronous Motor Based On High-frequency Signal Injection

In recent years the permanent magnet synchronous motor (PMSM) has been widely used in the power transmission areas due to its excellent performance, such as small size, low loss, high efficiency and so on. Precise control of PMSM needs rotor position information. The most commonly used method is mounting a mechanical sensor on the rotor shaft to measure the speed and position information of the motor rotor. However, high-precision, high-resolution speed and position sensors are usually expensive, so this method not only increases the cost of the entire system, but also causes a wiring complexity and limits the application drive in harsh environments. Therefore, research on sensorless control systems of PMSM has important and practical significance. It is mainly based on motor equation, which estimates the speed and rotor position information indirectly.The system structure of pulsating high-frequency voltage signal injection method is relatively simple to achieve and this method does not require a large number of coordinate calculations and digital filters.This paper analyzed the basic principle of pulsating high-frequency voltage signal injection method and established mathematical model of interior permanent magnet synchronous motor in the excitation of high-frequency signal.The control strategy based on pulsating high-frequency voltage injection method was studied. This method was used to estimate the PMSM’s rotor position information. The generated electrical signal of motor windings had rotor position information. Through the design of the PII control algorithm and polarity discrimination section to distinguish rotor’s N, S pole, the control system can achieve accurate position.A sensorless vector control system simulation model based on pulsating high-frequency voltage injection method was established and this paper made simulation experiments about the estimated and actual value of rotor position, the rotor position estimation error and the estimated and actual value of speed. Experimental results showed that the pulsating high-frequency signal injection method could accurately detect the position of the rotor in the whole speed range and the system had good static and dynamic response characteristics.A sensorless vector control system model based on pulsating high-frequency injection method which hardware core is DSP was developed and software and hardware was designed to achieve a PMSM control system’s sensorless operation. The paper made experiments for the control system. Experimental results showed that the rotor position detection method based on pulsating high-frequency signal injection method could achieve operation without a position sensor, insensitived to the motor’s parameter changes and also had good robustness for outside interference.