Switching Frequency Analysis Of Electric Vehicle Silicon Carbide Driver Under Urban Traffic Conditions

With the rise of the environmental protection campaign and the revolution in energy consumption,electric vehicles have gradually become one of the city’s main transportation means.The trend puts forward new requirements for motor drivers with high efficiency,high power density,wide operating range,and high reliability.After the advent of the new generation of wide bandgap power devices,Si C-based motor drivers showed up.They have the advantages of high switching frequency,low switching losses,high blocking voltage,and high operating junction temperature.Compared with traditional Si-based motor drivers,whose performance is capped by the physical limit of materials,Si C-based motor drivers can better meet the new requirements of electric vehicles for motor drivers.Given the wide motor speed range requirements of electric vehicles and the common urban road conditions of electric vehicles,the thesis analyzes the switching frequency of Si C-based motor drivers.The thesis discusses the research status and technical bottlenecks of electric vehicle Si C-based motor drivers.Besides,it introduces the common driving cycles and determines the common working scenarios of electric vehicles.To demonstrate that,a mathematical model of PMSM is established and the common control algorithm is introduced.The vector control strategy of PMSM with id=0 is choosen accordingly.Along with that,the thesis presents the model of voltage distortion caused by the switching process and pulse width modulation.It derives the expression of the distortion current and proposes a switching frequency selection scheme to minimize current total harmonic distortion.With the help of Simulink software,the low-speed driving model of electric vehicles is built,which verifies the aforementioned switching frequency selection scheme.Finally,the proposed switching frequency selection scheme is verified on a power electronics experimental platform with a Si C-based motor driver.The results of experiments and simulations indicate that for electric vehicles mainly used in urban road conditions,Si C-based motor drivers can boost their operating efficiency and simplify the control algorithm.