Research On Measurement Method Of IGBT Junction Temperature Based On Magnetic Nanoparticles

Insulated Gate Bipolar Transistors(IGBTs)combine the advantages of MOSFETs and BJTs.They are regarded as ideal switches with high switching speed and low switching loss,and are widely used in inverters and other fields.Temperature is the main factor that affects the instrument failure of IGBTs,the fast and accurate acquisition of IGBT junction temperature is of great significance for the study of failure mechanism,life prediction and reliability state assessment.However,it is very difficult to perform real-time measurement of junction temperature without damaging its package.In this thesis,the measurement method of IGBT junction temperature based on magnetic nanoparticles is studied.The single point temperature measurement technology of magnetic nanoparticles is combined with the junction temperature measurement model to design the temperature measurement system and realize the junction temperature real time measurement when the power signal is step signal.In this thesis,the RC thermal network model of IGBT is simplified firstly,and the second-order thermal network model is obtained by combining the heat dissipation system and simplified thermal network model.Then the step response equation of the second-order thermal network model is calculated,and the junction temperature measurement model while the power is step signal is obtained.Furthermore,the measurement process of IGBT junction temperature based on magnetic nanoparticles is proposed,including the acquisition of junction temperature measurement model parameters and the measurement of junction temperature based on magnetic nanoparticles.At the same time,the error of magnetic nanoparticle temperature measurement model and the error of the junction temperature measurement model are also simulated.After the model is established,the temperature inversion algorithm of magnetic nanoparticle temperature measurement is studied and a temperature measurement system is built.According to the magnetic nanoparticle temperature measurement model,four constraint equations are obtained.The Particle Swarm Optimization algorithm is used to compare the advantages and disadvantages of the four constraint equations,and then optimize the temperature inversion algorithm to enhance the algorithm's ability of the local search.The hardware part and the software part of the temperature measurement system are designed.The hardware part includes the excitation magnetic field generator and the weak magnetic detection system,and the software part includes the Digital Phase Sensitive Detection algorithm and the eliminating residual magnetism by software.Finally,the design of the experimental scheme and the analysis of the experimental results were finished.The feasibility of using magnetic nanoparticles for temperature measurement in IGBT working environment was verified,and the temperature standard error is 0.149 K and maximum error is 0.31 K.The real-time measurement of the IGBT junction temperature while the power is step signal is realized without destroying the package.