Study On Control Technology For High Speed Permanent Magnet Synchronous Motor

High-speed permanent magnet synchronous motor (PMSM) are more and more widely used in ultra-high precision machining and high performance machinery due to the merits of small size, high efficiency, high power density, small moment of inertia and fast dynamic response. The speed of high-speed PMSM can be up to tens of thousands revolutions per minute, or even hundreds of thousands revolutions per minute. The winding current frequency is higher. Due to the characteristics of high frequency high speed and harmonic existed in the inverter driven high-speed motor, the problem of large harmonic of high-speed PMSM power supply is getting worse. The issues of how to reduce the harmonics of power supply and how to realize the closed-loop control etc. need to be researched deeply in order to improve the performance of high-speed PMSM control system. The issues of high-speed PMSM special inverter and filter design, the system closed-loop control strategy, the rotor position and speed signal detection methods etc. have been studied in this paper. The main contents are as follows:(1) The design method of inverter with specific harmonic elimination (SHE) and adjustable switching mode is proposed by analyzing the influence of current harmonics on high-speed PMSM. When high-speed motor runs at different speed, the different function of switching mode inverter is used. 18-pulse inverter switching mode is used when high-speed motor runs at middle or lower speed. Switching angle is selected based on SHE to make the 5th and 7th harmonics minimum. The mathematical model of SHE single bipolar pulse control is established and the relationship between different modulation ratio and switching angles to eliminate the 5th and 7th harmonics is presented. 6-pulse inverter switching mode is used when high-speed motor runs at higher speed. The 5th and 7th harmonics at the output side of inverter can be eliminated by SHE filter. The simulation and experiment is studied for the proposed method.(2) The methods of adding second-order RLC or third-order LCL filter at the converter output side when use PWM converter is studied in order to effectively suppress high-speed PMSM power supply harmonics. The design method of the adaptive filter with adjustable inductor used at the inverter output side is proposed when the motor runs at higher speed with 6-pulse switching mode inverter. The simulation analysis and experiment is done between various filters proposed. The effectiveness of the proposed filtering method has been verified.(3) The strategy of polygon flux direct torque control (DTC) suitable for high-speed PMSM is proposed. The strategy of sensorless eighteen flux polygon DTC is used when high-speed PMSM runs at lower and middle speed region. The strategy of sensorless hexagonal flux DTC is used when the high-speed PMSM runs at high speed region. The switching method between two control modes is studied. Simulation and experimental study is done for the proposed control strategy.(4) An optoelectronic position sensor is studied and the signal processing circuit is desgined for ordinary sensor is not suitable for high-speed motor rotor position detection. The experiment has been done for the proposed method.(5) The experimental platform with DSP TMS320F2812 as the control core is built which can be used for the high-speed PMSM control system. The experimental research is done for polygon flux DTC with rated power 10kW, rated speed 12000r/min high-speed PMSM which has verified the correctness of the proposed method.