High-capacity capacitor overvoltage protection circuit adopting BOD (bistable optical device) element

Abstract

The invention relates to a high-capacity capacitor overvoltage protection circuit adopting a BOD (bistable optical device) element. The overvoltage protection circuit comprises a high-capacity BOD1 element, an energy storage capacitor C1 and an energy storage capacitor C2, a diode D1 and a diode D2, a divider resistor R1 and a divider resistor R2, a loop discharge resistor R3, a current-limiting resistor R4 and a current-limiting resistor R5 and a thyristor Q1; the R1 and the R2 are connected in parallel; a connecting line between the R1 and the R2 is sequentially connected with the diode D1 and the BOD1 element, the R4 and the R5; the C1 is connected to the left side of the diode D1; the R3 is connected between the BOD1 element and the R4; the C2 is connected between the R4 and the R5; the D2 is connected to the left side of the R5; the R2, the C1, the R3, the C2 and the D2 are sequentially connected in parallel; and the Q1 and the D2 are connected in parallel. The circuit provided by the invention can be triggered continuously during protecting the voltage value.

Description

technical field [0001] The invention relates to a circuit, in particular to a large-capacity capacitor overvoltage protection circuit using a BOD element. Background technique [0002] A schematic diagram of a thyristor overvoltage protection circuit using BOD components is shown in figure 1 . BOD components are often used in this protection circuit. Moreover, multiple BOD components can be connected in series to achieve a reasonable protection voltage value. For the volt-ampere characteristics of BOD components see figure 2 . figure 2 V in BO That is, the operating value of the BOD element, when the voltage across the BOD element is lower than V BO , the leakage current flowing through the BOD element is very small, about 100uA, when the voltage across the BOD element reaches V BO , and the current I flowing through it BO When it reaches about 15mA, the BOD element is turned on, and the voltage at both ends V H It is about 4-6V, and the maximum current flowing th...

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Problems solved by technology

And if it is a large-capacity capacitor to be protected, and when the capacitor is overvoltage, the BOD cannot quickly reduce the voltage on the large-capacity capacitor to 0 after the action, but only cuts off the charging circuit of the large-capacity capacitor, resulting in a large-capacity capacitor. voltage will be maintained for a longer period of time, then R 1 The power consumed on will be larger, R 1 It must be realized with a larger volume of resistors, which increases the size of the circuit board

And different protection voltage values ​​need to use different BOD components, which makes it more troublesome in engineering applications

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