Circuit for detecting voltage changing rate of two ends of thyristor

Abstract

The invention discloses a circuit for detecting a voltage changing rate of two ends of a thyristor. The circuit comprises: a capacitor Ct connected in series and coupled across the two ends of a thyristor T; a sampling resistor Rt; a protection module, a signal conditioning module and a dv / dt detection and signal sending module which are all connected with the two ends of the sampling resistor Rtin parallel. Detection of dv / dt at the two ends of the thyristor T and output of a standard exceeding alarm signal are realized by the dv / dt detection and signal sending module; overvoltage protectionand large current bypass of the signal conditioning module and the dv / dt detection and signal sending module are realized by the protection module; and conditioning of the alarm signal output by thedv / dt detection and signal sending module are realized by the signal conditioning module, so that the pulse width of the alarm signal is larger than the minimum recognizable pulse width of the peripheral control device. According to the circuit for detecting a voltage changing rate of two ends of a thyristor, the detection circuit is simple in principle, rapid and reliable in action and can be used for protecting the thyristor from damage caused by excessive dv / dt.

Description

technical field [0001] The invention relates to the field of control and protection of electronic power devices, in particular to a detection circuit for the rate of change of voltage at both ends of a thyristor. Background technique [0002] When the thyristor is in the off state, when the rate of change of the voltage across the thyristor (dv / dt) is greater than a certain value, due to the existence of the gate junction capacitance, a large enough gate current may be generated, causing the thyristor to turn on by mistake, which in turn causes the device Work abnormally. During the turn-off period of the thyristor, due to the existence of the reverse recovery charge, the thyristor current will continue to flow in the reverse direction after being reduced to zero. This process is called the reverse recovery period of the thyristor device. If the thyristor on the thyristor during the reverse recovery period If the forward voltage rise rate is too high, the thyristor will be ...

AI Technical Summary

Problems solved by technology

[0003] In the application process of thyristor devices at home and abroad, it is usually adopted to reduce the dv / dt at both ends of the thyristor by connecting a resistance-capacity absorption circuit in parallel at both ends of the thyristor, but this will increase the capacity of the resistance-capacity absorption circuit, increase the overall loss of the thyristor device, and suppress dv / dt limited ability

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