Research And Application On Instantaneous Thermal Characteristic Of Power Thyristors

With the development of high voltage direct current and pulse power technology,power thyristor is widely used nowadays. Many its electrical characteristics and lifetime areattached to temperature. And its failures can be aroused duo to over temperature. Soresearch on thermal characteristic of thyristor is beneficial for improvement and protectionof thyristor. At first relationship between electrical characteristics and internal parametersof thyristor is introduced and summarized in this paper. Then it can be found most of thefailure mechanism is attached to instantaneous over temperature of thyristor. To analyzethis characteristic, a model of whole thyristor based on heat conduction theory isestablished. According to the solution, it can be concluded that the thickness of metal sinkin thyristor doesn’t affect the instantaneous peak temperature. So a prototype of slimthyristor is manufactured to validate the calculation. Furthermore, to obtain detailinformation about the internal temperature field on the wafer of thyristor, a model based ongoverning equation of semiconductor is established. The calculation results show that thereis a hot spot in the middle of cathode area which is a potential cause for failure. Meanwhile,a lot of experiments are implemented to investigate the safe operation area of thyristor. Andthe relationship curve between amplitude of surge current and pulse width of it is obtained.At the end of this paper, method to measure the instantaneous junction temperature isdiscussed and proposed.