| Air conditioning systems are indispensable in today’s buildings,air volume is a key factor to achieve the stability of indoor temperature,humidity,cleanliness and comfort.Sensorless vector control can save motor cost and improve fan operational stability.This paper takes the surface mounted permanent magnet synchronous motor(PMSM)as the research object and studies the air volume control technology based on sensorless permanent magnet fan.According to the characteristics of surface mounted permanent magnet motor,the mathematical model of the motor is established,the principle of SVPWM technology is analyzed,then the model is simulated with actual motor parameters.The foundation is provided for the follow researches of vector control without position sensors.The sensorless control technology is used to reduce the cost of the motor.After analyzing the principle and construction method of the state observer,the sensorless Luenberger state observer is constructed.Aiming at low control precision of the Luenberger observer algorithm,a method of Kalman filter combined with multi-parameter PLL is designed.Firstly,the estimated back-EMF is filtered by Kalman filter,then the PLL parameters are segmented and self-adjusting according to different speeds.The simulation model verifies that the estimation error does not increase with the changing of rotation speed and it has good improvement effect.In order to realize the air volume control without static pressure sensor,operational characteristics of the centrifugal fan and pipe network pressure theory are analyzed.According to the fan characteristic curve and working points,the basic conditions of controlling the air volume are deduced.A air volume control strategy of PMSM with fan load is designed,it uses current iq control instead of traditional power control,and the control accuracy of air volume can be improved.Finally,the fan vector control experiment platform is finished in this paper,including circuit schematic design,PCB hardware design and software flow design.Furthermore the test prototype is made.Compared with BLDC motor,the performance of test prototype is more efficient and more smoothly.The phase difference between the motor current waveform and the hall sensor position signal is measured,it shows that the method of Kalman filter combined with multi-parameter PLL has better estimation accuracy.Then the air volume control experiment proves that the control strategy can achieve higher precision of air volume control. |
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