Lifetime Preasumption And Extension Of Power Control Unit For Electric Vehicle Application

In order to adapt to the dual-carbon goal and the continuous demand for electrification of transportation,it is an inevitable trend of history that electric vehicles gradually replace fuel vehicles.Electric vehicles have very high requirements for reliability,however the operating conditions of vehicle motor controllers are poor which leads to its high failure rate and short lifetime.Naturally,the motor controller become the key technical problems for the safe and reliable operation of electric vehicles.Aiming at the lifetime preasumption and life improvement of automotive motor controllers,this theis analyzes the load characteristics of electric vehicles,evaluates the lifetime of the motor controller,reveals the basic laws that affect the lifetime of the motor controller,and proposes methods for improving the lifetime of the motor controller.The theoretical model is verified through simulation analysis and experimental results,which provide basic theory and technical support for the optimal design of vehicle motor controllers.This article has mainly obtained the following innovative research results:(1)The load characteristic model of the vehicle motor controller is established,and how the driving cycle and road slope angle and driving habits influence the mission profile of motor controller are analysed.Based on the driving cycle and road profile of electric vehicles,the dynamic model of electric vehicles,the mathematical model of the vehicle motor,and the control algorithms of the motor,the calculation process of the mission profile of the vehicle motor controller is put forward in detail.Based on a large number of standard driving cycle and measured driving cycle,the influence of driving habits and road slope angle information on load characteristics is analyzed.(2)A unified model of modulation algorithms is constructed,a loss model of automotive power module is established,and the junction temperature law of power devices is revealed.According to the basic principles of CPWM and DPWM modulation algorithms,combined with the representation method of the zero sequence component,a unified mathematical model of the modulation algorithm is created.Based on the power loss law of the switching period and the sine period,the power loss model of the vehicle power module was established,and the PLECS simulation software was used to verify the feasibility and effectiveness of the power loss model,and reveals the regulation law of the modulation algorithm on the loss of the device,as well as the load characteristics.Based on the electric-thermal multiphysics analysis method,a 3D thermal network model of the automotive power module is established,and the COMSOL simulation software is used to analyze the influence of the driving cycle and the modulation algorithms on the junction temperature of the device.(3)A lifetime evaluation method and lifetime improvement methods for vehicle motor controllers are estabilished.Based on the mission profile model of the electric vehicle,the electric-thermal coupling model of the power module,the rain flow count method,the cumulative damage theory,and the lifetime model of the power module,the lifetime evaluation method of the vehicle motor controller is established.Combining the mission profile of electric vehicles,taking into account influencing factors such as driving cycle,road slope angle,modulation algorithms,gearboxes,etc.,the lifetime damage law of vehicle motor controllers is studied.From the perspectives of electrical control,mechanical transmission and weight reduction,the useful lifetime improvement method of the motor controller are raised.(4)The simulation loading experiment platform of the vehicle motor controller was built,and the feasibility and effectiveness of the mission profile model,power loss model,electric-thermal coupling model,and lifetime evaluation model were verified.Focusing on factors such as modulation algorithm,load current,power factor angle,switching frequency,DC bus voltage,etc,the experiment analyzes the influence law and adjustment method of device junction temperature.For analysis tools such as mission profile model,power loss model,thermal network model,and lifetime evaluation model,experiments have verified the accuracy and effectiveness of the basic model,and the feasibility of lifetime evaluation and lifetime improvement of the vehicle motor controller is demonstrated.