Powe supply unit and air conditioner with the power supply unit

Abstract

The invention provides a power supply unit wherein the conduction angle of input current is widened through simple control and thereby the power factor is improved and the harmonic component of the input current is reduced. The power supply unit is provided with a rectification circuit that rectifies the voltage of alternating-current power supply, a reactor connected with the rectification circuit, a power-factor improvement circuit that includes a plurality of switching elements and capacitor circuits and is fed as input with the output voltage of the rectification circuit, a change-over switch portion that is connected between the rectification circuit and the power-factor improvement circuit and switches the state of conduction of a current path formed between them from the state in conduction to the state out of conduction and vice versa, a change- over switch control portion that controls the state of conduction of the change-over switch portion, a pulse signal control portion that generates and outputs pulse signals for turning on and off the individual switching elements in the power-factor improvement circuit, and a switch driving portion that receives the pulse signals from the pulse signal control portion and drives the switching elements in the power-factor improvement circuit.

Description

technical field [0001] The invention relates to a power supply device which converts alternating current into direct current, reduces high-order harmonic components of input current, improves power factor, and provides required power supply voltage and an air conditioner using the power supply device. Background technique [0002] In the past, as an AC-DC conversion circuit, a capacitor input rectifier circuit has been used in various fields. It inputs AC voltage into a diode rectifier circuit to obtain a pulsating current output, and uses a capacitor to smooth the pulsating current to obtain a DC voltage. In the capacitor input type rectifier circuit, because the current conduction angle of the input current is narrowed, the power factor is poor, and the reactive power is large, so not only the power cannot be used effectively, but also there are many high-order harmonic components, which are harmful to the connection to the Machines in the same power system constitute obst...

AI Technical Summary

Problems solved by technology

[0011] However, in the Figure 26 In the conventional power supply device shown, although the power factor can be improved with a simple structure, the improvement effect is small, and a satisfactory power factor cannot be obtained.

Moreover, there is also the following problem: in order to obtain a high power factor with this circuit structure, the value of the choke coil needs to be increased, which will lead to an increase in the size of the structural components and the resulting increase in loss

In addition, when switching the energized state of the relay circuit 130, the output voltage changes greatly, which may adversely affect the load 105.

[0012] in addition, Figure 27 In the power supply unit shown, although the power factor can be greatly improved by simple switch control, when the power supply unit is used in an air conditioner, etc., there are the following problems: First, when the input When the choke coil is 200V, the loss in the choke coil increases due to the enlargement of the choke coil; second, because the size of the choke coil is different when the input is 100V and when the input is 200V, the circuit cannot be shared; Three, when switching the energized state of the relay circuit 130, the output voltage changes greatly, which may bring adverse effects to the load 105

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