Surge current suppression circuit

Abstract

The invention provides a surge current suppression circuit. After the suppression circuit is electrified, an alternating-current power supply charges a C1 via a D1, a D2, an R1, an R2 and an R3. The voltage of the C1 is stabilized to be the clamping voltage of a voltage-regulator tube ZD1. The positive-end level of the C3 is the input voltage after rectification, the waveform is the sine half-wave and the C3 does not have charging access. The voltage of the C3 is 0, thus, the negative end level of the C3 changes along with the positive-end voltage and change conditions of the power voltage is directly reflected. Before the power voltage is lower than the Q1 operating voltage, a Q1 and a Q2 are kept in the turned-off state. When the power voltage changes to be lower than the Q1 operating voltage, the power level state is reflected by the negative-end level of the C3 and then the Q1 is conductive. Current flows into the grid electrode of the Q2 via the Q1 and an R6 from the C1, so level of the Q2 is increased and exceeds the open threshold voltage, and the Q2 is conductive. When the power voltage charges the C3 via the Q2, the instantaneous value of the power voltage is quite low and the surge current can be suppressed.

Description

technical field [0001] The invention relates to the field of power supply protection circuits, and more specifically, to a surge current suppression circuit. Background technique [0002] Switching power supply equipment is a capacitive load for the power grid. When the device is connected to the grid, it is in a short-circuit state and absorbs a huge current from the grid, which is called the inrush current (Inrush current). Switching power supply equipment has caused a threat, if it is not suppressed, it will cause abnormal or even damage to the equipment. [0003] At present, the commonly used suppression method is to connect impedance devices in series in the circuit, such as power resistors, thermistors, and thermistors with relays. In these methods, the contradiction between the surge suppression effect and the device's own loss is difficult to reconcile, so the suppression effect is not good. Each specific method has its own problems that are difficult to overcome: ...

AI Technical Summary

Problems solved by technology

In these methods, the contradiction between the surge suppression effect and the device's own loss is difficult to reconcile, so the suppression effect is not good

Each specific method has its own problems that are difficult to overcome: the resistance of the thermistor becomes very large in a low temperature environment, causing difficulty in starting up, and the resistance value becomes small at high temperatures, losing the ability to suppress surges; the use of relays Short life, prone to failure after multiple boots

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