Research For Permanent Magnet Motor Drive System Based On The Electrolytic Capacitor-less Power Converter

Permanent magnet synchronous motor(PMSM)has attracted wide attention due to their high power density,high efficiency,and excellent control performance.The DC side of the PMSM drive system take advantage of electrolytic capacityors to stabilize the bus voltage fluctuations.However,largecapacity electrolytic capacityors have shortcomings such as short life and low reliability.So,this paper uses film capacitors instead of electrolytic capacitors.In addition,in order to enable the PMSM to be applied in more severe situations,the position sensorless control technology is used to obtain the rotor position information more reliably.In order to suppress the DC voltage fluctuation of the bus in the electroless capacitor drive system and improve the power factor of the system,this paper proposes a new type of power decoupling circuit.In order to reduce the position sensorless observation accuracy of the Electrolytic Capacitorless drive system,this paper proposes two improved control strategies.The key research are as follows:Firstly,it shows the PMSM rotor structure;elaborate the PMSM mathematical model and coordinate transformation theory in each coordinate system;then briefly introduce the PMSM space vector control principle,and explain the debugging method of the speed and current loop controller to lay the foundation for subsequent chapters.Secondly,the relevant features are described in detail from three aspects: the power characteristics,the connection between the PF and the DC bus voltage fluctuations,and the influence of the bus voltage fluctuations on the position sensorless control technology.This paper proposes a new type of electrolytic capacitor power decoupling circuit to achieve the purpose of improving the power factor and reducing the bus voltage fluctuation.The working principle,working mode of the topology is explained in detail,and the setting calculation basis for key device selection is given.Thirdly,the design principle and key details of the sliding mode variable structure control system are introduced.The sliding mode variable structure control is introduced into the control of the traditional PMSM drive system.A sliding mode observer is constructed and the rotor position information is estimated through the phase-locked loop.The impact of the capacitive drive system on the position sensorless control technology,an improved sliding mode observer using a delay filter combined with a synchronous rotating filter is proposed;in order to simplify the filtering process,after further research,this article proposes an improved sliding mode observation based on SOGI Device.Finally,in order to verify the feasibility of the theory in this paper,an experimental platform for the electroless capacitor drive system was established.The drive circuit,position detection circuit,voltage,current detection circuit,etc.are used to introduce the construction of the hardware part of the experimental platform in detail.The software part introduces the system main program flow chart,PWM interrupt service flow chart and each subroutine flow chart.Simulation and experimental verification the feasibility of the new topology and improved sensorless control technology proposed in this paper.