Research On Open-Winding Permanent Magnet Synchronous Motor Drive System With Dual Inverter For Electric Vehicle

With the advantages of high-efficiency,high-density,easy to obtain a wide speed range by field-weakening,permanent magnet synchronous motor(PMSM)has been extensively used in the electric automobile.However,some notable adverse effects such as intense EMI,stability problem,high shaft voltage,risk of demagnetization etc.are noted in the applications of dc/dc boost converter cascaded two-level PWM inverters.High-efficient,high-density,lightweight integration permanent magnet machine drive system is one of the key technologies of electric vehicle electric to be resolved in "Thirteen Five".Combined with the “Twelve Five" 863 State Science and Technology electric vehicle technology and system integration key issue of projects "Research of industrialization technology of permanent drive motor and its control system with high cost-effective"(No.2011AA11A236),and 863 electric vehicle major projects,key technology research evaluation of motor system commonality(863-2011AA11A238),"Research on key generic technologies of Motor System and Evaluation Setup ",this thesis carry on the research of wide speed control of PMSM based on power electronics technology.Wide speed permanent magnet synchronous motor electric drive techniques are summarized compendiously for domestic and overseas studies in the prolegomenon of this dissertation.Also,the aim and significance for the research are demonstrated.Bilateral inverter fed open-winding permanent magnet synchronous(DINV-PMSM)motors as new electric vehicle drive system is presented in this paper,and which wide speed stability state characteristics,voltage space vector pulse width modulation(SVPWM)algorithm,wide speed vector control strategy are analyzed and simulation.The main contents of this paper and the contributions are as follows:1.Aiming at the problem of low power density and poor reliability of the existing hybrid electric vehicle multi-energy system,a modularized drive topology of the bilateral inverter fed open-winding motor is adopted.By reducing the series size of the battery,significantly improve the system's power density and reliability and fault tolerance.Its inherent three-level characteristics effectively reduce the electromagnetic interference and switching losses,decrease output harmonic distortion.2.Focus on the problem that the permanent magnet synchronous motor in depth flux-weakening area,the motor drive system of DINV-PMSM can effectively increase the high-speed running range by increasing the utilization of the DC bus.According to the HEV operation mode,unit power factor control,quadrature voltage control method and maximum voltage control scheme can be flexibly chosen to improve the mileage.The SVPWM algorithm of bilateral 2-levle inverter in the maximum voltage control mode is verified by experiments.The algorithm is simple and easy to implement.3.Multi-phase multi-level drive system often is adopted in low-voltage high-power HEV.In this paper,a general simplified SVPWM algorithm for multi-phase multi-level bilateral inverters is proposed.The algorithm converts the reference vector into a multidimensional orthogonal space,and converts the polyphase multi-level into a multi-phase two-level SVPWM algorithm using elementary matrix transform.This algorithm avoids the complicated graph analysis and sector identification,and it is useful for the low cost and quick implementation of SVPWM algorithm.It proves especially suitable for real-time implementation with low cost FPGA due to its low computational complexity.Dual 3-level inverter and dual 5-level inverter of three-phase simulations validate the proposed algorithm.4.Aiming at the wide speed vector control of DINV-PMSM motor,it is proposed to identify the weak magnetic field by zero voltage vector action time.Compared with existing methods of voltage feedback and speed feedback,this algorithm has low cost and good robustness.It is not difficult to achieve faster dynamic response.Finally,the experimental development platform with 32-bit DSP processing chip 2812 as the core is created.The hardware and software design is elaborated and the flowcharts of vector control software are introduced.The experimental research of an open-winding PMSM of 1.1kW power ratings is conducted.It indicates that the systems researched in this paper have benefits of wide speed range operation and it's the maximum speed is extended about 40%.Its steady-state and dynamic-state indicators comply with the requirements of electric vehicle operation.