Active Thermal Management Control Of PWM Inverter Based On The Estimation Of Real-time Temperature

In this thesis,the IGBT in the PWM inverter under unstable condition is used as the object of research.The method of real-time junction temperature estimation was analyzed,the control method which can be used to guide the active thermal management of the power device,was studied through the theoretical analysis and simulation verification.The main work is as follows:Improving device reliability is the fundamental goal of active thermal management.The thesis analyzed the package structure and failure mechanism of the device,and obtained a life prediction model which can be used to describe the reliability of the inverter.Based on the analysis of the electric properties,it is found that the average junction temperature and junction temperature fluctuation are the key factors that affect the reliability of the device,so as to determine the general model of active thermal management.Real-time junction temperature estimation is the basis of active thermal management.This thesis presented an electro-thermal coupling model that can be used for real-time temperature estimation.The real-time loss value can obtained,using the datasheet provided by the power device manufacturer and the data provided by the inverter real-time conditions,and the change of the junction temperature of the IGBT can be simulated more accurately.When the result in simulation compared with IPOSIM software,it showed that the electro-thermal coupling model proposed in this paper can evaluate the real-time junction temperature of the device quickly and accurately.The output frequency is unstable in the practical application of the inverter,We proposed the regional-oriented guidance of the active thermal management control ideas.By discussing the influence of output frequency on junction temperature and device life,we discovered that when the output frequency is low,the junction temperature fluctuation amplitude is a little large,and the device is more likely to fail.In this thesis,the regional-oriented guidance of the active thermal management control strategy can take full account of the effect of the output frequency on the device junction temperature performance.The switching frequency is adjusted by hysteresis control when the temperature fluctuation is monitored at low output frequency.The current is clipped by the average junction temperature of the device when the output frequency is higher.This thesis realized the active thermal management control strategy on the two-level three-phase PWM inverter system.Combined the advantages of internal thermal management and external thermal management,the thesis put forward the active thermal management strategy of multi-parameter joint regulation of junction temperature.The method proposed in thesis is verified in MATLAB/Simulink by a lot of simulation.The results show that the control strategy can effectively reduce the average junction temperature and junction temperature fluctuation,ameliorating the utilization of heat capacity,improving the reliability and extend the lifetime of the device.