Active-control valley fill circuit and control method thereof

Abstract

The invention discloses an active-control valley fill circuit and a control method thereof which are mainly applied to pre-stage power factor correction and energy accumulation of a switching power supply. The active-control valley fill circuit comprises an alternating-current power supply, a current rectifier, a load, an energy storing capacitor, a switch circuit and control circuit, the alternating-current power supply is connected with an input end of the current rectifier, an output end of the current rectifier is connected with the load, the switch circuit comprises two power ends and a control end of a power channel, the energy storing capacitor is serially connected with the two power ends of the switch circuit and is then parallelly connected with an output end of the current rectifier, and the control end of the switch circuit is connected with the control circuit. According to the control method, by means of presetting threshold voltage, switching between power supplying of the load and energy storing of the energy storing capacitor is realized according to changes of relationships among alternating-current phase position voltage, voltage at two ends of the energy storing capacitor and the threshold voltage. The active-control valley fill circuit has the advantages that a circuit structure is simple, a power factor is improved, output voltage is not higher than alternating-current crest voltage, and the minimum value of the output voltage can be set.

Description

technical field [0001] The invention relates to the field of power supply circuits, in particular to an active-controlled valley-filling circuit and a control method thereof, which are mainly used in pre-stage power factor correction and energy storage of switching power supplies. technical background [0002] At present, switching power supplies have been widely used in various fields of industry and civil use due to their advantages of high efficiency and small size. The switching power supply circuit includes a pre-stage power factor correction circuit and a post-stage switching power supply circuit. The function of the pre-stage power factor correction circuit is to improve the power factor of the electrical equipment, reduce the reactive current, and reduce the pollution of the reactive current to the power grid. There are two main types of common power factor correction circuits at present, as follows: figure 1 and figure 2 shown. [0003] figure 1 It is a current...

AI Technical Summary

Problems solved by technology

The minimum output voltage of the passive valley-filling circuit is less than half of the peak value of the AC power, which requires that the subsequent switching power supply must adapt to a wider input voltage range, which leads to a decrease in the performance index and an increase in the cost of the subsequent switching power supply, and also leads to The application of this valley filling circuit is limited

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