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

Permanent magnet synchronous motor is widely used in industrial production and household electrical appliances because of its advantages of simple structure,convenient maintenance and high power density.In general,the drive system is powered by uncontrolled rectifier,and the DC-link requires large capacitance electrolytic capacitor to maintain the stability of the voltage.However,the electrolytic capacitor has the defects of low life,poor reliability and large volume,which can lead to the failure of the drive system.Film capacitors in alternative electrolytic capacitor of the electrolytic capacitor-less permanent magnet motor drive system can effectively solve the above problems,but electrolytic capacitor-less drives has low quality of the grid,unstable DC-link voltage and poor motor performance.In response to above problem,this paper proposes a novel electrolytic capacitor-less permanent magnet motor drive system,on the basis of analyzing its working principle,the realization method of the motor operation performance and the grid quality is discussed.The main contents of this paper are as follows:1.Compared with the traditional drive system,the characteristics of the electrolytic capacitor-less drive system are very different and need to be analyzed deeply.Firstly,the power characteristics of the electrolytic capacitor-less system are introduced.The relationship between the power characteristic and the DC-link voltage ripple is obtained.Then according to the DC-link voltage ripple is deduced its links with the motor performance.Finally,the system has to reduce the voltage ripple to improve the motor performance.In addition,the double closed loop vector control scheme is introduced for future research.2.Based on the above research results,electrolytic capacitor-less drives has the problem of large DC-link voltage ripple,so put forward a novel electrolytic capacitor-less power converter,analyses the working principle of the different work modes,and the key parameters of converter to calculate.The novel power converter is characterized by the design of the film capacitor C1 voltage as a large ripple pattern,which makes most of the grid power ripple stored in the power decoupling circuit C1,and reduces the influence of DC-link power ripple,thus the DC-link voltage ripple is reduced.3.Research on control strategy of the novel electrolytic capacitor-less permanent magnet motor drive system.The DC-link voltage control method based on harmonic current injection is put forward.By injecting a moderate amount of 3rd harmonics into the grid,the grid output power ripple is reduced and the DC-link voltage ripple is further reduced under the condition that the system power factor is not less than 0.95 and the grid output current harmonics meet the corresponding standard.In order to realize high performance of the motor under the condition of the DC-link voltage ripple,this paper proposes a hybrid vector control program based on repetitive controller to improve the drive system steady-state property through repetitive controller,and the drive system dynamic response is improved by the PI controller.Finally,the stability analysis and design of the repetitive controller are described in detail.4.On the basis of theoretical analysis and simulation,a digital control experiment platform based on TMS320F28335 was constructed for experimental research,the feasibility and effectiveness of the novel electrolytic capacitor-less permanent magnet motor drive system is verified.