Why is thyristor easy to breakdown?

Why is thyristor easy to breakdown?

1. Overvoltage breakdown:

Overvoltage breakdown is one of the main factors causingthyristor breakdown, and the ability of the thyristor to withstand overvoltage is almost timeless. Even in a short period of milliseconds, overvoltage can be broken down. Therefore, in practical application circuits, RC absorption circuits must be connected at both ends of the thyristor to avoid sudden overvoltage caused by various irregular interference pulses. If thyristor breakdown often occurs, please check whether the components of the absorption circuit are burnt out or fail.

2. Overcurrent and overheating breakdown:

In fact, overcurrent breakdown and overheating breakdown are the same thing. Overcurrent breakdown refers to the thermal effect that occurs inside the thyristor chip when the current passes through it, causing the chip temperature to increase. When the chip temperature reaches 175 ℃, the chip will fail and cannot recover. Under normal operating conditions, as long as the operating current does not exceed the rated current of the thyristor, this type of thermal breakdown will not occur. As the principle of overcurrent breakdown is caused by an increase in temperature, and the process of temperature increase requires a certain time, overcurrent in a short period of time (from a few hundred milliseconds to a few seconds) is generally not breakdown.

3. Overheating breakdown:

The overheated breakdown referred to here refers to the thermal breakdown that occurs when the operating current does not exceed the rated current of the thyristor. The main factor causing this breakdown is the poor operation of the auxiliary heat dissipation device of the thyristor, which causes the thyristor chip to overheat and cause breakdown.