Power Factor Correction And Rotor Position Estimation For Permanent Magnet Synchronous Motor Control System

Permanent Magnet Synchronous Motor (PMSM) has been widely used in many fields because of its high power factor, great power density, small size and high efficiency, however, speed control system of PMSM with intermediate or small capacity will lead to low power factor and power harmonic polluting grid by using inverter mode. One effective solution is increasing the power factor. In traditional PMSM control system, rotor position is detected by position sensor, this method will cause high fault rate but high cost. So it is of great significance for simplifying the structure and improving the system stability of PMSM by rotor detection algorithm instead of position sensor.The paper investigates the principle of power factor correction (PFC) and analyzes some kinds of PFC circuit structure. Select Boost type as PFC circuit structure due to high working voltage of PMSM control system. Aiming at the deficiency of average current method and predictive control method, a control algorithm for stable operation of unity power factor combining the two methods above. The algorithm can compensate the current nearby zero-crossing of input voltage by adding the duty ratios of input voltage obtained by average current method and predictive control method, make the control system reach the unity power factor without detecting zero-crossing of input voltage, keep ripple of output voltage less then3%and inhibit the input disturbance. Meanwhile, use PFC smooth switching technology to ensure the stable operation of unity power factor by controlling the ratio of duty ratios to reduce the impulse for control system during switching.Existing rotor position detection method based on counter electromotive force method can not be used at180°commutated motors, aiming at this problem, a non-sensor position detection algorithm using direct position error estimation is proposed. This is a new counter electromotive force algorithm that the actual rotor position is calculated based on angle difference between actual coordinate and introduced new coordinate. The algorithm is not dependent on the motor’s counter electromotive force; it can also improve the algorithm accuracy and practicality through differential term approximation.An inverter air conditioner experimental platform based on STM32F103for1kW PMSM is designed, and simulations and experiments of the two proposed algorithms are carried out on the platform. The results indicate that the power factor is not less than0.995by using stable operation control algorithm based on improved average current method for predicted compensated unity power factor when input voltage is220VAC±20%and output load between400W-1500W. Direct position error estimation algorithm can ensure long term stable operation of non-sensor vector control system. Figures (53), tables (4), references (62).