Method and system for randomly switching alternating current

Abstract

The invention relates to a method and a system for randomly switching alternating current. The system comprises a voltage detecting circuit, a current detecting circuit, a first switching circuit, a second switching circuit, a control circuit, a pulse width modulator (PWM) and an APFC circuit, wherein the first switching circuit is used for switching on or off a main power supply; the second switching circuit is used for switching on or off a reserve power supply; the control circuit is used for controlling the first switching circuit and the second switching circuit to switch on or off and transmitting a pulse signal to the PWM; the PWM is used for modulating an output dutyfactor according to the pulse signal transmitted by the control circuit; the APFC circuit is used for receiving the output dutyfactor of the PMW so as to control the output current, and thereby the linear rectification of the output current is realized to ensure the synchronization of the output voltage and the current phase of the APFC circuit. The state of the power supply can be automatically recognized by adopting the random switching so as to adapt to power supplies in different environments, and the switching time is greatly reduced and fixed. The current linear rectification can be randomly switched as alternating current to solve the peak interference brought by the random switching, and the power compensation is carried out to realize the minimum loss of circuit power.

Description

technical field [0001] The present invention relates to a power switching method and system, more specifically, to a random switching method and system for alternating current. Background technique [0002] The existing AC switching circuit uses the voltage zero-crossing switching technology, which has the disadvantage of long switching intervals, that is, when the main AC power failure is detected, the logic controller sends a control signal to the solid-state zero-crossing switch. The switching is realized when the standby power crosses zero, and no transient peak interference is generated. The switching time depends on the phase difference between the main power and the backup power. In the existing AC zero-crossing switching circuit, the switching must wait until the voltage crosses zero to realize switching, and the switching time is uncertain (depending on the phase difference between the main power supply and the backup power supply), and the switching time is too lon...

AI Technical Summary

Problems solved by technology

[0002] The existing AC switching circuit adopts the voltage zero-crossing switching technology, which has the disadvantage of long switching intervals, that is, when the main AC power failure is detected, the logic controller sends a control signal to the solid-state zero-crossing switch. Switching is realized when the standby power crosses zero, and no transient peak interference is generated. The switching time depends on the phase difference between the main power and the backup power

In the existing AC zero-crossing switching circuit, the switching must wait until the voltage crosses zero to realize the switching, and the switching time is uncertain (depending on the phase difference between the main power supply and the backup power supply), and the switching time is too long (about 25ms), so that The circuit loss increases; at the same time, the switching time process will also bring high-frequency interference to the power supply, which will have a serious impact on the power supply of high-speed centralized circuits with high power requirements.

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