Circuit for restraining surge current

Abstract

The circuit for restraining the surge current is located between the DC voltage and a load. The load has the parallel energy storage capacitnace. The suppressing circuit includes the first current-limited circuit and the second current-limited circuit. The first current-limited circuit includes the first resistance, the first controlled switch and the second controlled switch. The first resistance is connected to the first controlled switch in series. The connection between the second current-limited circuit and the first resistance as well as the first controlled switch is the parallel connection. The second current-limited circuit includes the second resistance and the third controlled switch-capacitor. The second resistance is connected to the third controlled switch in parallel as well as connected to the energy storage capacitor in series.

Description

technical field [0001] The invention relates to a surge current suppressing circuit, in particular to a surge current suppressing circuit applied to a power input module in a communication power supply system. Background technique [0002] Inrush current (Inrush Current) usually occurs at the moment when the power supply is initially turned on. At this time, unexpected or unwanted transient current (Transient Current) will be generated, which can easily generate noise and even cause damage to power supply components or loads. [0003] figure 1 It shows an inrush current suppression circuit (InrushLimiting Current) applied to a DC power supply in the prior art. A resistor R and a receiving capacitor are connected between the input DC voltage U and the system (including a load and a parallel system energy storage capacitor Cs). Control the switch SW and a capacitor C to complete the function of suppressing the surge. When the power supply of the power supply is initially tur...

AI Technical Summary

Problems solved by technology

When the power supply of the power supply is initially turned on, the resistor R performs a preliminary current limiting function. Since the capacitor C has not started charging at this time, the overall current value is quite high, which may damage the electronic components on the power supply; then, the capacitor C The charging of C is completed and the current decreases, but its value is still very high, so that the electric group R continues to emit a lot of heat; finally, the controlled switch SW such as a relay (Relay) is turned on to achieve the current bypass ) The effect of the resistor R prevents the overall efficiency from being reduced due to the heat dissipation of R. However, the disadvantage of this method is that the characteristic of the relay is that it is easily damaged when it is continuously on, and another form of surge is generated at the moment the relay is turned on. The overall power supply is easily damaged

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