Study On Thermal Characteristics Of Thyristor Under Heavy Frequency And Large Surge

Electromagnetic emission is a new concept of emission technology that uses pulsed power discharge to propel the projectile.As a key component in the pulse power supply,the performance of the switch directly affects and restricts the development of electromagnetic emission and pulse power technology.Thyristor is a widely used switching device in electromagnetic pulse power supply.It usually works under a single large surge condition.However,with the development of electromagnetic emission technology,new requirements for the large-frequency surge capability of thyristors are put forward.When the thyristor is under heavy-frequency and large surge conditions,the heat accumulation caused by the continuous surge current is easy to cause damage to the device.Therefore,this paper studies the thermal characteristics of the thyristor under this condition and provides the electromagnetic emission pulse power supply design.According to the basis,the main research work of the paper is as follows.The paper introduces the research background of thyristor re-frequency surge and its application in electromagnetic emission pulse power supply,and analyzes the demand for thyristor performance under electromagnetic emission working environment.In the electromagnetic emission work process,the thyristor has to withstand large inrush current,rapid current change rate,high-speed change of forward and reverse high voltage,especially in recent years,electromagnetic emission for the pulse power supply re-frequency surge surge demand,the thyristor has a great influence on the working life of the thyristor.It needs to be evaluated by thermal analysis.Through the summarization and analysis of various traditional thermal analysis methods,the traditional thermal analysis methods exist in the case of thyristor switching at high voltage and high current.Limitations,the need to improve the accuracy through experiments combined with simulation calculations.In this thesis,the calculation method of heat transfer characteristics of thyristor based on thermal impedance network is studied.The thermal impedance simulation program of a thyristor using Foster model is programmed by matlab software.The program can be used to calculate the temperature of the device during a single large surge current.Change;At the same time,using the 10 ms surge flow indicator in the device manual,a method for quickly calculating the junction temperature of the thyristor after a single surge current is derived,which is convenient for engineering use.For the same working condition,the maximum junction temperatures calculated by the two methods are 171 °C and 175 °C,respectively,and the error is less than 2.3%,which is consistent with the experimental results.By comparison,it can be found that the results of the thermal impedance network and the fast calculation method are basically the same,indicating that the fast calculation method can be used for the evaluation of the flow capacity of the thyristor switch in the pulse power supply.Taking the KPC 4600-34 thyristor as an example,the thyristor finite element thermal simulation model is established according to the device parameters provided by the manufacturer,and the thermal characteristics simulation analysis based on ANSYS Icepak software is carried out.Based on the above work,it is commonly used for electromagnetic emission.Three-inch,four-inch,five-inch,and six-inch thyristor devices were simulated for thermal characteristics,and life predictions were performed according to the life curve provided by the manufacturer.After three consecutive operations,the 3-inch pulse thyristor MKPX 050-065 The highest junction temperature reaches 316 °C,the device can't work under this condition for a long time;the 4-inch pulse thyristor MKPC150-052 has a transient maximum junction temperature of 200 °C,and its service life is expected to be about 851 rounds;5 inches The transient maximum junction temperature of the pulse thyristor MKPD230-052 is 112 °C,and the service life is expected to be about 15135 rounds.The maximum transient junction temperature of the 6-inch pulse thyristor MKPE 330-052 is 88 °C.The expected service life is about 39810 rounds.The paper carried out an experimental study on the thyristor re-frequency surge surge flow,designed and built a pulse flow test platform,including high voltage pulse voltage measurement,pulse high current measurement,thyristor temperature measurement and high power re-frequency simulation load equipment.The thyristor flow performance test and test work under the condition of heavy frequency and large surge can be completed,and the peak current of the experiment can reach 150 k A.The thyristor temperature was measured 5 minutes after the end of the discharge.The maximum temperature range of the 3-inch thyristor was 89.7 ° C,the maximum temperature range of the 4-inch thyristor was 56.6 ° C,and the maximum temperature range of the 5-inch thyristor was 43.9 ° C.Through the comparison of experimental data and finite element simulation results,as the size of the thyristor increases,the agreement between the simulation and the measured results becomes better and better.Therefore,the finite element simulation model used in this paper is used to evaluate the thyristor repetitive flow.A means of performance,with high accuracy,can be used in electromagnetic transmission pulse power supply design work.