Research And Design Of A Novel Electrolytic Capacitor-less Power Converter For Permanent Magnet Synchronous Motor

In the traditional drive system of permanent magnet synchronous motor(PMSM),the electrolytic capacitor has the disadvantages of low life and poor reliability,which is the main factor of system failure.The use of thin film capacitors instead of electrolytic capacitors can significantly improve the life and reliability of the system.However,it is difficult to suppress the pulse energy of the system,and the power quality of the grid and the motor performance can not be taken into account.In order to solve the above problems,this paper presents a electrolytic capacitor-less power converter,which has a power factor correction function,and the harmonic and power factor of grid meet the IEC61000-3-2 standard.The active power decoupling circuit can effectively reduce the voltage fluctuation,and improve the static and dynamic performance of the permanent magnet synchronous motor.At the same time,the DC bus voltage is almost equal to the peak value of the grid voltage,which can avoid the problem of increasing the cost of the existing electrolytic capacitor power converter.The main work of this paper is as follows:First of all,the defects of electrolytic capacitor and the possible problems of using electrolytic capacitor power converter are analyzed.The feasibility and practicability of using thin film capacitor instead of electrolytic capacitor are discussed.From the two aspects of the improvement of the control strategy and the research of the new topology,the current situation of the research on the electrolytic capacitor-less at home and abroad is introduced.Secondly,this paper introduces the classification,development history and application of permanent magnet synchronous motor(PMSM).The principle of coordinate transformation is analyzed,and the mathematical model of permanent magnet synchronous motor in different coordinate system is established.Then,the paper puts forward an electrolytic capacitor power converter topology,its working principle is analyzed,the mathematical expression of the key parameters are derived.And the control strategy without electrolytic capacitor of the power converter is proposed in this paper from two aspects.A control method of voltage feed forward motor is studied,which significantly improve static and dynamic performance of the motor,while taking into account the grid side power quality.Finally,the system hardware platform based on TMS320F28335 as the core control chip is set up.On this basis,the simulation and experiments are carried out to verify the proposed converter.The results show that the proposed converter can achieve high power factor and reduce current harmonics.In addition the converter c meet the IEC61000-3-2 standard and achieve good performance of the motor.At last,the cost and the volume of the conventional boost power converter and the electrolytic capacitor-less power converter are compared.