Research On Control System Of PMSM Based On Single-Phase To Three-Phase Converter Without Electrolytic Capacitor

The speed regulation systems of PMSM have been widely used in an increasing number of application areas.The conventional drive systems of PMSM usually adopt AC-DC-AC converter,in which the DC link uses a large electrolytic capacitor to stabilize the bus voltage.Due to the large volume and short life of the electrolytic capacitor,the miniaturization,reliability and lifespan of the entire drive system are severely limited.At the same time,the conventional drive systems also need the power factor correction circuit in order to meet the harmonic standard of the input current,which increases the size,loss and cost of the system.Therefore,the drive systems of PMSM which use small film capacitors instead of large electrolytic capacitors have received more and more attention.And the influence of bus capacitance on system performance and high-power-factor control strategy are the research hotspots in the PMSM drive systems without electrolytic capacitor.This paper explores the impact of bus capacitance on system performance firstly.By establishing the equivalent circuit of system,the relationship between bus capacitance and bus voltage and motor performance is obtained through the analytical analysis,which will provide the theoretical basis to the selection of bus capacitor.In order to obtain the high power factor of the input side,based on the power balance,a high power factor control strategy based on current tracking is proposed in this paper.The q-axis current command of the motor is obtained according to the relationship between the input and output power balance of the inverter.And to further increase the input power factor,a q-axis current tracking component based on the fluctuation of bus voltage is added to the q-axis current reference.In order to improve the track performance of q-axis current,the repetitive controller is added to q-axis current loop.The d-axis current of the motor is obtained according to the principle of "Average Voltage Limit" to meet the requirement of flux-weakening when the bus voltage reduces to a low level.Finally,taking a 1kW PMSM as the object,the experimental platform was built.The simulation and experiment are carried out to verify the feasibility of the high-power-factor control strategy proposed in this paper.The result proves that using the control strategy proposed in this paper can reduce the harmonic components of input current and improve the input power factor effectively.