Lifetime Evaluation Of Silicon Carbide Devices For Vehicle Inverters Under Different Control Strategies

Electric vehicle inverters are the core components of electric vehicles and require very high reliability.Silicon carbide(Si C)devices have the advantages of high temperature resistance,high voltage resistance,low loss,etc.,and have been widely used in automotive inverters.However,the driving conditions of electric vehicles are complex,and the working environment is also very harsh,which is likely to cause the failure of power devices.Therefore,the reliability of power devices has become a major challenge to the reliability of electric vehicles.Life assessment is an important means to improve the reliability of electric vehicle inverters.Life assessment of automotive inverter silicon carbide devices is of great significance.It is for the reliability assessment of electric vehicles,the design of electric drive systems,and the optimization of control strategies.Provide theoretical foundation and technical support.This paper takes the automotive inverter silicon carbide device as the research object,and evaluates and studies the lifetime of Si C device and its influencing factors under vector control and model predictive control.Secondly,a simulation model of the vehicle electric drive system under vector control is built on the PLECS platform.Based on the simulation model,the junction temperature and loss changes of the vehicle inverter Si C device under typical operating conditions of electric vehicles are analyzed.The rain flow counting method is used to process the junction temperature curve.According to the Miner fatigue cumulative damage theory and the life model,the expected time life and mileage life of the Si C device for the vehicle inverter are calculated.At the same time,the influence of different operating conditions such as switching frequency,motor speed,motor torque and ambient temperature on the junction temperature and lifetime of Si C devices under vector control is analyzed.Thirdly,a MATLAB/PLECS joint simulation model using model predictive control was built,and the electric-thermal simulation of the vehicle electric drive system under typical working conditions was carried out,and the junction temperature and loss of the Si C device of the vehicle inverter under the model predictive control were obtained.Changes and life prediction results.The influence of different operating conditions on the junction temperature and lifetime of Si C devices under model predictive control is analyzed.Finally,the thermal performance and motor control performance of Si C devices under vector control and model predictive control are compared and analyzed.The results show that the Si C device under model predictive control has better thermal performance and longer lifetime expectancy,while the motor control performance under vector control is better.