Research On New Energy Vehicle Motor Controller Based On Discrete SiC MOSFET

The excessive consumption of oil by traditional fuel vehicles in energy consumption has brought about problems such as energy security,ecological environment,climate change,etc.The development of new energy automobile industry has become an inevitable development trend of the automobile industry.The core of automotive electrification is to replace the fuel power system with an electric powertrain.The motor controller is an important part of the electric powertrain,which determines the power performance and power system cost of the entire vehicle.At present,silicon power devices are commonly used in new energy vehicle motor controllers.Due to the limitations of silicon semiconductor materials,the potential of relying on silicon-based power devices to improve the performance of new energy vehicle motor controllers is very limited,and it is difficult to meet current new energy vehicle motor controllers.For the performance requirements such as efficiency and power density,there is an urgent need to design silicon carbide(SiC)power devices with better performance to replace silicon-based power devices into motor controllers.In this paper,from the perspective of improving the overall performance of new energy vehicle motor controllers and improving the feasibility of technical applications,a 200 k W-class new energy vehicle motor controller is designed using discrete SiC MOSFET devices with excellent performance and low cost.The thesis first analyzes the research progress of new energy vehicle motor controllers and summarizes the advantages of SiC motor controllers in new energy vehicle applications.Then,using circuit simulation to study the two key problems of discrete SiC in the application of high-power motor controllers,explored the effects of different parameters on the SiC drive circuit and SiC parallel current sharing,and designed a fast protection function.Driving core;on this basis,according to the requirements of new energy vehicles for efficiency and power density,the performance indicators of discrete SiC motor controllers were determined,the overall structural design plan was proposed,the power circuit and control circuit were designed,and the analysis was analyzed.The overall loss of the power loop has completed the design of the motor controller hardware system based on SiC discrete devices;developed a vector control algorithm for permanent magnet synchronous motors based on DSC,designed a modular software control program based on TI TMS320F28335;and finally,built a Discrete SiC MOSFET motor controller test platform,tested the static performance of SiC motor controller,compared and analyzed the output current waveform,controller efficiency,motor control system efficiency of SiC and Si motor controller,and the temperature under different power Rise.The results show that the designed SiC driving core has excellent driving effect,which can effectively suppress the crosstalk of SiC MOSFET in the switching process,and the short circuit protection function is fast and effective.The designed parallel scheme of discrete SiC devices has good dynamic and static current sharing effects;when the phase current of the same frequency is output at the same carrier frequency,the SiC motor controller has a smoother phase current waveform than the Si IGBT motor controller And higher control accuracy;the maximum efficiency of the SiC motor controller is 99.3%,and the ratio of the high efficiency area of the controller efficiency and motor control system efficiency greater than 95% is more than 20% higher than the Si IGBT motor controller;The temperature rise during operation is low,and the radiator water temperature rises only 9.2 °C at peak power,while the Si IGBT radiator temperature rises to 25 °C when the motor controller is operating at peak power.