Composite type high-efficiency power factor correction circuit

Abstract

The invention discloses a composite type high-efficiency power factor correction circuit which comprises an alternating current input circuit, a rectification circuit, at least one inductor, two flywheel diodes, two electronic switches and two capacitors. The composite type high-efficiency power factor correction (PFC) circuit has the advantages of high efficiency of a BUCK type correction circuit, low output ripple and small voltage and current stress of a switching tube and also has the advantages of high power factor of a BOOST type correction circuit, and moreover, the composite type high-efficiency PFC circuit shares the same inductor and is an economic and high-efficiency PFC correction circuit.

Description

technical field [0001] The present invention relates to a power factor correction (PFC) circuit of an AC-to-DC conversion circuit, in particular to a combined circuit using BUCK step-down and BOOST step-up PFC, which improves the efficiency of the circuit and reduces the voltage of the switch tube and the current stress, reducing the output ripple current. Background technique [0002] With the enhancement of global environmental awareness, the application of green and environmentally friendly power supplies will become more and more popular in countries around the world, especially in developed countries and regions. Among power supplies, switching power supplies have the highest efficiency. Conventional switching power supplies, due to the The input of the converter (AC-DC) has rectification and filter capacitors, so the PF (power factor) value of the AC is very low, generally around 0.6 to 0.8, the harmonic interference is large, and a large number of low power factor pow...

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Problems solved by technology

[0002] With the enhancement of global environmental awareness, the application of green and environmentally friendly power supplies will become more and more popular in countries around the world, especially in developed countries and regions. Among power supplies, switching power supplies have the highest efficiency. Conventional switching power supplies, due to the The input of the converter (AC-DC) has rectification and filter capacitors, so the PF (power factor) value of the AC is very low, generally around 0.6 to 0.8, the harmonic interference is large, and a large number of low power factor power supplies are connected to the grid. It causes the power grid to be inefficient and has a large amount of harmonic injection, which interferes with the normal operation of the power grid and affects the safety of the power grid. Therefore, most countries in the world now require power factors greater than 0.9 for switching power supplies with a power greater than 75W. , The conventional power factor correction circuit is divided into passive correction and active correction. Passive correction requires a large inductance, which consumes a lot of copper and is bulky. In order to save copper consumption and reduce the size of the power supply, the main Power factor correction circuits basically use active correction circuits, and active power factor correction circuits are mainly BOOST step-up circuits, and a small part of active power factor correction circuits use BUCK step-down circuits. Each correction circuit has its advantages and disadvantages; the advantage of BOOST step-up power factor correction circuit is high power factor, the disadvantage is that the switch tube voltage and current stress are large, the efficiency of the circuit is lower than that of BUCK circuit, and the output ripple is large; BUCK step-down power The advantages of the factor correction circuit are high efficiency, small switch tube voltage and current stress, and small output ripple. The disadvantage is that the power factor is lower than that of the BOOST circuit, and when the input voltage is lower than the output voltage, the circuit cannot work.

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