Novel power-on surge current suppression circuit

Abstract

The invention relates to a novel power-on surge current suppression circuit. The novel power-on surge current suppression circuit comprises a power supply circuit, a surge current suppression resistor end voltage sampling and comparison circuit, a relief resistor, a metal oxide semiconductor (MOS) transistor, a surge current suppression resistor and an optional small-capacity high-frequency filtering capacitor, wherein the power supply circuit comprises a rectification diode, an energy storage filtering capacitor and a buck voltage limitation circuit, the surge current suppression resistor end voltage sampling and comparison circuit comprises a first end voltage sampling resistor, a second end voltage sampling resistor, a reference voltage source and a comparator, a drain of the MOS transistor is connected with a DC-DC converter, a source of the MOS transistor is connected with a negative end of a rectifier bridge, a grid of the MOS transistor is connected with an output end of the power supply circuit, an input end of the power supply circuit is connected with an AC N/L end, the surge current suppression resistor is connected in parallel to the drain and the source of the MOS transistor, the relief resistor is connected in parallel to the grid and the source of the MOS transistor, and the optional small-capacity high-frequency filtering capacitor is connected between a positive end and the negative end of the rectifier bridge. With the power-on surge current suppression circuit disclosed by the application, the power-on surge current is suppressed better, the power consumption of an MOS transistor driving circuit is low, the starting speed is fast, and the power-on time allowed again is short.

Description

technical field [0001] This application relates to an AC-DC switching power supply, and specifically relates to a novel power-on surge current suppression circuit, which is generally applicable to AC-DC converters with various topological structures such as flyback, forward or APFC. Background technique [0002] In the AC-DC drive circuit, after the alternating current is rectified, it is directly or indirectly filtered by a large capacitor. The terminal voltage of the filter capacitor rises from zero at the moment of power-on. If it is just near the maximum value of the sinusoidal alternating current when the power is turned on, there will be a transient high current of up to hundreds of amperes at the moment of power-on, which will affect the power grid and the AC-DC converter connected in series. Devices in the input channel, such as fuses, power frequency rectifier diodes, and filter capacitors, have caused severe high-current shocks. The size and duration of the tran...

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Problems solved by technology

For example, the cost of connecting NTC thermistors in series is the lowest, but the AC input current always flows through the thermistors during normal operation, resulting in high power consumption of NTC resistors, high temperature and high current for a long time, and more seriously, power failure Finally, you must wait for the NTC resistor to cool down to normal temperature before powering on, otherwise the thermistor will lose its ability to suppress the surge current and reduce the reliability of the AC-DC converter; the AC zero-crossing trigger method requires a thyristor rectifier , and also need to add auxiliary power supply, AC zero-crossing detection circuit, high cost and complicated circuit; although the parallel connection of power resistor and electromagnetic relay can better solve the problem of the startup surge current and the power consumption of the current-limiting resistor during the normal operation of the converter The contradiction, but the relay pulls in a large current, the mechanical contact reliability is poor, and the volume is large

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