Research On Efficiency Optimization And Electromagnetic Characteristics Of Permanent Magnet Synchronous Motors For High Speed And Large Power

Permanent magnet synchronous motors(PMSM) for high speed and large power have many advantages, such as compact structure, high power density, high efficiency and flexibly varied form and size, due to eliminating the traditional gear box and actualizing straight drive. The PMSM for high speed and large power are applied in the blower, compressor, expander, gas waste heat power generation, flywheel energy storage and so on widely. The energy-efficient industrial AC motors have been the focus of the international research, because of the shortage of the world’s energy and the requirement of the sustainable development. The research is not sufficient currently and needed urgently on the electromagnetic characteristics and the efficiency optimization of the PMSM for high speed and large power.Traditional equivalent circuit method has the disadvantages of ignoring l eakage flux and lack of analytical precision, because the magnetic field is simplified to the magnetic circuit and the any cross-section magnetic flux density of the magnetic circuit is assumed uniform everywhere. The finite element method is used to calculate electromagnetic parameters including the pole arc coefficient and no-load magnetic flux leakage factor, which have great influence on characteristics of the PMSM for high speed and large power. With the equivalent magnetic circuit, the impact of the motor combination property such as efficiency, current, electromagnetic torque, et al. on load and speed is researched. The results show that the field-circuit method has higher computational efficiency and accuracy compared to the equivalent circuit method.To achieve the efficiency optimization design of PMSM for high speed and large power, the time-step finite element is used to analyze the effect of stator slot width, air-gap length, thickness and material of rotor retaining sleeves on electromagnetic losses and efficiency of PMSM for high speed and large power. With the goal of reducing losses and improving efficiency, taking into account the motor starting, speed regulating and load performance in the meantime, the concrete strategy of efficiency optimization design of PMSM for high speed and large power is proposed. The results show that the efficiency can be improved using optimization scheme.D-q coordinate mathematical model of PMSM for high speed and large power considering iron losses is established to achieve the efficiency optimization control of PMSM for high speed and large power. Then, loss-minimizing control strategy based on space vector pulse width modulation(SVPWM) is proposed, and the simulation of starting and speed regulating electromagnetic transient process of PMSM is actualized through independent programming based on MATLAB/SIMULINK control module. The results show that the electromagnetic losses can be reduced effectively by loss-minimizing control method while the fluctuation of current and torque can be weakened.The PMSM experiment platform is built to test losses characteristics. The studies show that the iron losses between measured and calculated are agreed, and the errors of theoretical calculation compared measured don’t exceed 20%, which proves the correctness of the theoretical calculation.The research works have important referenced value for the electromagnetic analysis, efficiency optimization design and drive control of PMSM for high speed and large power.