因di/dt过高烧毁大功率可控硅机理的研究

STUDY OF POWER SCR BURNT BY EXCESSIVE di/dt

在大容量、高电压可控硅的应用中,常出现可控硅局部过热而损坏的事故。究其原因,大多是因可控硅电流扩散速度远小于线路di/dt数值所致。其解决办法是:采用扩散速度快的可控硅,但因其价格昂贵而无法推广。现根据可控硅触发电流大,扩散速度亦大的特点,可采用强触发方式。当感性负载时还必须用双强窄脉冲触发,也可以在主回路中串接空心电感及在过压保护回路中串联一定的电阻来限制di/dt的数值。文中还就脉冲变压器的设计问题作了说明。

In application of power SCR of large capacity and high voltage, the. fault of burning of SCR caused by partial excessive heat appears frequently. The reason of which is that the diffusion velocity of the SCR current is,far below that of the di/dt value in the line. To solve that is to use SCR of high diffusion velocity. but it can't be popularized for its high cast. According to the characteristic of SCR, the heavier the trigger current, the higher will be the diffusion velocity, a strong triggering mode may be used. In case of Inductive load, it is. necessary to trigger by double strong narrow-pulse. To limit the value of di/dt, an air core inductor or a resistor of certain value may be connected in series in the main circuit or in the over-voltage protection circuit respectively.The paper also describes the problems in design of pulse transformer.