On-line Measurement And Algorithm Of Junction Temperature Of Power Diode

With the continuous development of power semiconductor devices,it has been widely used in different fields.The decline of reliability of device and the shortage of lifetime become more serious because of high junction temperature.Accurate measurement of junction temperature of devices has undoubtedly great significance for the study of thermal characteristics of devices and the improvement of device reliability.About the devices junction temperature measurement methods,there are mainly physical,optical and electrical methods,and the electrical methods is divided into switching method and non-switching method.About junction temperature with a high current method in non-switching methods,there are the following problems:1.The lack of the available equipment of measurement of junction temperature.2.There is no certain method about obtaining the junction temperature by voltage-current data in measuring.3.There are errors in measurement results due to the existence of noise and the limitations of the method itself.In this article,the measurement of junction temperature of power diode with big current online is discussed,and a pulse measuring instrument which can measure junction temperature online is researched and designed.The Biharmonic algorithm is used to solve the problem of obtaining the junction temperature by voltage-current data,the Kalman filtering algorithm is used to correct the results of measurement.The feasibility of the pulse measurement instrument and the algorithm is verified by the measurement of a certain type of device,the results are discussed.The details of this paper include:1.The paper discusses the principle of the junction measurement method by big current and the issues existing in the practical application,include the selfheating caused by big current,the processing of data points.Based on above description and discussion,the principle of the pulse measurement instrument and the feasibility of the actual manufacture are discussed.2.According to the design parameters of the pulse measurement instrument,the overall design of the hardware is presented.The design and manufacture of the pulse power board,data acquisition board,control board and communication board are discussed.3.Based on the hardware design,the software design of the pulse power board is discussed,including the system on chip and the computer system.A simple pipeline is realized in the system on chip which is validated by simulation;the computer system written by C++ in Visual Studio 2013 environment,the structure and the main classes are introduced.4.This paper proposes the use of Biharmonic algorithm to solve the obtaining temperature by voltage-current data points,the principle of Biharmonic algorithm is introduced,and compared the performance with other interpolation algorithms.And this paper proposes the use of Kalman algorithm to reduce the error of measurement,the principle of Kalman algorithm is introduced and the performance of it is simulated and verified.5.Base on above work,the pulse measurement instrument is assembled and completed.A certain type of diode was measured to verify the accuracy of measurement results and the feasibility of the Biharmonic algorithm.Finally this paper discussed the effort and significance of Kalman filtering algorithm.