A power circuit and its control method

Abstract

The application provides a power supply circuit and its control method. In the power supply circuit, two output capacitors connected in series are arranged between the positive and negative poles of the DC side of the bridge rectifier unit, and the controllable semiconductor switch circuit is arranged in the bridge Between one of the neutral and live wires on the AC side of the rectifier unit and the connection point of the two output capacitors; its input voltage mean value sampling comparison circuit and input voltage change rate comparison circuit respectively output the mean value comparison result and the change rate comparison result; its control unit is based on the mean value The comparison result and the change rate comparison result control the on-off state of the controllable semiconductor switch circuit, so that the power supply circuit is equivalently transformed into a voltage doubler rectifier circuit when the average value and change rate of its own input voltage are lower than the corresponding threshold, and when its own input When the average value or rate of change of the voltage is higher than the corresponding threshold, it is equivalently transformed into a bridge rectifier circuit; in order to realize the automatic switching of the rectification mode of the power circuit, it avoids the failure and explosion caused by the overvoltage caused by the user forgetting or dialing the wrong switch.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and more specifically, relates to a power supply circuit and a control method thereof. Background technique [0002] In the existing AC input rectification mode switchable power supply circuit, a bridge rectification circuit, a switch, and two electrolytic capacitors in series are generally used to realize the following rectification mode switching function, such as figure 1 Shown: When the power supply circuit is in the voltage doubler rectification mode, the maximum value of the rectified output voltage is about twice the peak voltage of the power grid; When the circuit is in bridge rectification mode, the maximum output voltage after rectification is about the peak voltage of the power grid, such as Among them, Uac is the effective value of the voltage between the AC input line AC-L and AC-N; Udc is the maximum value of the voltage between the rectified positive DC voltage VDC and...

AI Technical Summary

Problems solved by technology

However, the terminal user is not professional in the operation of the switch inside the device, and often forgets or dials the wrong switch. Therefore, it often causes the power supply to be connected to the input high-voltage AC when the switch S1 is closed, that is, in the voltage doubler rectification mode. The nominal voltage is 220-240Vac; at this time, electrolytic capacitors (such as figure 1 Shown C1 and C2) will fail and explode due to overpressure, resulting in economic losses and reputation losses for customers and equipment manufacturers, as well as a series of safety hazards

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