Research On Full-speed Range Sensorless Control Technology For Fan-type Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM)has more and more applications in motor drive control systems due to its simple structure,small size,light weight,low loss and high efficiency.At the same time,the position sensorless control technology has become a research hotspot of permanent magnet synchronous motor control.Both domestic and foreign scholars have proposed different sensorless control strategies.In this paper,aiming at the application of permanent magnet synchronous motor in the fan,some control methods for stable operation under simpler,more efficient and multicondition conditions are proposed,which realizes the stable operation of the permanent magnet synchronous motor in the full speed range without position sensor.The practical application of magnetic synchronous motors is of great significance.The research work of this paper mainly includes:(1)In the zero-low speed section,an I/F starting strategy of variable current amplitude is proposed.The magnitude of the current amplitude is combined with the motor speed,that is,the current amplitude of the I/F starting is updated in real time according to the speed of the motor.,thereby reducing the energy loss of the entire control system and improving the operating efficiency of the motor during the I/F starting phase.At the same time,the two-position method is used to locate the rotor rotor to ensure the success rate of the positioning.At the later stage,the direct start method(no rotor positioning stage)is also tried,and the closed-loop operation state is entered.(2)The PMSM starting strategy is optimized.A method of speed-repetitive injection of permanent magnet synchronous motor based on terminal voltage detection is studied,which enables the fan to start smoothly and operate stably under various working conditions(upwind,downwind,static).(3)The control method of electrolytic capacitor without large capacitance is studied.By detecting the bus voltage in real time and calculating the voltage compensation coefficient,the current fluctuation and torque ripple caused by the bus voltage fluctuation are reduced.It greatly simplifies the hardware layout of the control system,reduces the cost of the enterprise,and also improves the stability of the system(4)In the motor state switching strategy,the I/F starting section is cut into the downwind starting procedure,instead of directly cutting in the current and speed double closed loop control phase,which solves the disadvantage that the large inertia fan type load state switching may fail,ensuring that the entire control link is normal.Stable operation.