Research On Control Strategy Of Electrolytic Capacitor-less Permanent Magnet Synchronous Motor Drive System Fed By Single-phase AC Source

Traditional permanent magnet synchronous motor(PMSM)drive system has poor grid side index and low reliability of DC-link large electrolytic capacitor,which increases the system cost and decrease the lifetime of system.These disadvantages restrict variable speed motor drive system composed of PMSM and high-power converter to get more extensive application.The drive system scheme with small capacity replacing the large electrolytic capacitor can improve the system reliability,prolong the lifetime and reduce the system cost.Hence,it became a research post in recent years.In this paper,the single-phase input electrolytic capacitor-less PMSM drive system is studied.The control strategy based on inverter power control is discussed to achieve high power factor and low grid current harmonics.Firstly,the hardware circuit characteristics of the system are studied,which are divided into two kinds of topological structures: no grid inductance and series inductance.Secondly,considering the achievement of grid high power factor and low grid current harmonics,the control method and strategies of the inverter power are discussed,and the loop stability of inverter power is analyzed as well.Then,the inverter power controller and the voltage feedforward strategy are designed for compensating the periodic fluctuation of DC-link voltage.In addition,when there is inductor in the grid side,LC resonance is introduced,so the resonance suppression method based on active damping is necessary.In order to reduce the harmonics of grid current with inductance,the inverter power control method is improved to adapt the change of the system.The control strategies studied and proposed are preliminarily verified by the computer simulation.Finally,the physical experiments on the PMSM platform are carried out,and the experimental results are basically consistent with the simulation results.The results shows that the control strategy proposed in this paper can improve the grid power factor and reduce the grid current harmonics,which make the requirements of EN61000-3-2 can be achieved.What’s more,in order to illustrate the engineering realization value of the scheme,further physical experiments are carried out on air conditioning compressor,and the experimental results are in line with expectation.