Research On Control Of Permanent Magnet Synchronous Motors Without Electrolytic Capacitor

The motor is an important machine indispensable for the normal operation of modern society.It converts electrical energy into mechanical energy and is widely used in all walks of life,production and life.In recent years,permanent magnet synchronous motors have stood out among many types of motors due to their low cost and long life,and have been favored by the market.The main circuit of the permanent magnet synchronous motor drive system mostly adopts the AC-DC-AC circuit form,using large-capacity aluminum electrolytic capacitors in parallel with both ends of the DC bus.Due to the large size and short life of aluminum electrolytic capacitors,permanent magnet synchronous motor drive systems often have poor stability.Studies have shown that 60% of the faults in the motor control system are caused by electrolytic capacitors,and the environment of the motor equipment is more and more changeable.Today,its drawbacks are becoming more and more obvious.Replacing large-capacity aluminum electrolytic capacitors with small-capacitance capacitors not only saves equipment space,but also reduces the probability of failure.This drive structure has attracted more and more attention.This article will study the control of permanent magnet synchronous motors driven by electrolytic capacitor circuits under the framework of vector control.Firstly,analyze the structure of the permanent magnet synchronous motor,the control object of the system,introduce decoupling thinking,introduce the mathematical model of the permanent magnet synchronous motor in three coordinate systems,and combine the control block diagram to explain the principles of each link of the vector control,and introduce Several vector control methods under different conditions are presented,and simulations are carried out to verify the effectiveness of vector control.Secondly,a permanent magnet synchronous motor drive topology without electrolytic capacitor is proposed,and the advantages and disadvantages of permanent magnet synchronous motor drive without electrolytic capacitor and the scope of application is summarized.The reasoning analysis of how to improve the power factor of the permanent magnet synchronous motor driven by the electrolytic capacitor circuit is carried out,and a high power factor non-electrolytic capacitor permanent magnet synchronous motor control scheme based on the current fluctuation is proposed,and the simulation is carried out in the MATLAB/Simulink environment,The simulation results show that the scheme can effectively improve the power factor and reduce the electromagnetic pollution of the motor system to the power grid.Finally,around TI’s TMS320F28335 chip,the peripheral circuit and control program is designed and the test platform is built.The vector control performance and the current following effect under the drive of no electrolytic capacitor,the motor speed and the network measurement current are studied.The experimental results show that Electrolytic capacitor control overcomes the shortcomings of traditional aluminum electrolytic capacitors with high failure rate and low lifespan.It can also control the speed fluctuations in a small range,and can also improve the power factor of the grid side,which has certain practical significance.