CN201947169U - Stagger active PFC (power factor correction) circuit of inverter air conditioner - Google Patents

Abstract

The utility model relates to a stagger active PFC (power factor correction) circuit of an inverter air conditioner, which provides a novel full wave active PFC scheme. Two small PFC branch circuits connected in parallel work in a positive half-wave period and a negative half-wave period of alternating current respectively, thereby effectively reducing the volume and noise of reactors and simultaneously reducing capacities of direct electrolytic capacitors. The stagger active PFC circuit is provided with bridge rectifiers connected to two ends of an alternating current power supply in parallel and a pair of two-way power factor branch circuits. Current input end and output end of the two-way power factor branch circuits are overlaid, and a phase difference of the two-way factor branch circuits is 180 degrees. Two small PFC circuits are arranged at the position where a single bigger PFC circuit is disposed originally. The two small PFC circuits with halved power are connected in parallel, and the input end and the output end of the two small PFC circuits are overlaid, thereby reducing input current ripples and output current ripples caused by two inductive currents.

Description

Staggered active PFC circuit of variable frequency air conditioner

Technical Field

The utility model provides a be applied to inverter air conditioner's active PFC circuit of alternating expression belongs to the domestic appliance field.

Background

Due to the use of low-carbon environmental protection technology, the cognition degree of consumers on the high-energy-efficiency variable-frequency air conditioner is continuously improved, and the domestic variable-frequency air conditioner is rapidly popularized.

The PFC factor correction technology for forming the driving board of the variable-frequency air conditioner is mainly divided into the technical types of passive PFC, partial active PFC and full-wave active PFC.

The passive PFC technology has the defects of difficult harmonic wave passing, large element volume and the like;

the volume of part of the active PFC is still larger, and a larger installation space is needed;

full-wave active PFCs exist at low efficiency because they do not start during the positive half-wave or negative half-wave cycle of the ac. In addition, such PFC reactors have high noise and require an electrolytic capacitor having a large capacity.

This patent application is made in view of this.

SUMMERY OF THE UTILITY MODEL

Active PFC circuit of inverter air conditioner alternating expression, its design aim at solve the problem that above-mentioned prior art exists and propose a novel active PFC scheme of full wave to two parallelly connected little power factor correction branch roads of each other work respectively in the positive half-wave of alternating current, burden half-wave cycle, realize reducing reactor volume and noise effectively under high switching frequency operating condition, reduce the capacity of direct current electrolytic capacitor simultaneously.

In order to achieve the above design purpose, the interleaved active PFC circuit of the inverter air conditioner comprises:

a bridge rectifier and a group of 2-path power factor branches are connected in parallel at two ends of an alternating current power supply. Wherein,

the current input end and the output end of the 2-path power factor branch circuit are mutually overlapped,

the phase difference of the 2 power factor branches is 180 degrees.

According to the characteristics of the basic scheme, 2 small power factor branches which are connected in parallel and have half-reduced power and overlapped input ends and output ends are arranged at the original position where a single large power factor correction circuit is placed, and the 2 small power factor branches work in the positive half-wave period and the negative half-wave period of alternating current respectively with the phase difference of 180 degrees, so that input current ripples and output current ripples caused by two inductive currents can be reduced.

In a further improvement, a boosting inductor and a power IGBT are connected in series in each power factor branch.

As above, the staggered active PFC circuit of the inverter air conditioner of the present invention has the advantages of:

1. a novel full-wave active PFC technical scheme is realized, and the volume and noise of a reactor can be reduced under the working state of high switching frequency.

2. Since the noise of the reactor can be reduced without arranging an electrolytic capacitor with a larger capacity, the whole drive board can be reduced to achieve the design purpose of miniaturization.

3. Based on the characteristics of the full-wave active PFC technology, high efficiency is realized in the full cycle of alternating current, and the use power can be increased to 4kW so as to be applied to a high-power variable-frequency air conditioner controller.

Drawings

The present invention will now be further described with reference to the accompanying drawings

FIG. 1 is a schematic diagram of an interleaved active PFC circuit of the inverter air conditioner;

fig. 2 is a graph of different types of PFC power versus time.

Detailed Description

Embodiment 1, as shown in fig. 1, an interleaved active PFC circuit for an inverter air conditioner includes,

a bridge rectifier and a group of 2-path power factor branches are connected in parallel at two ends of an alternating current power supply,

the current input end and the output end of the 2 power factor branches are mutually overlapped, and the phase difference of the 2 power factor branches is 180 degrees.

The boost inductor L1 and the power IL1 are connected in series in one power factor branch, and the boost inductor L2 and the power IL2 are connected in series in the other power factor branch.

As shown in fig. 2, the inductor energy EsL required by the conventional single-stage active PFC is

$E_{\mathrm{SL}}=\frac{1}{2}{\mathrm{<figure-callout\; id="2"\; label="LI"\; filenames="DEST\_PATH\_HDA0000056138720000011.png"\; state="\{\{state\}\}">LI</figure-callout>}}^2$

Total inductive energy of staggered active PFC

Is composed of

$E_{I({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="DEST\_PATH\_HDA0000056138720000011.png,DEST\_PATH\_HDA0000056138720000012.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2)}=\frac{1}{2}L{\left(\frac{I}{2}\right)}^2+\frac{1}{2}L{\left(\frac{I}{2}\right)}^2=\frac{1}{4}{\mathrm{<figure-callout\; id="2"\; label="LI"\; filenames="DEST\_PATH\_HDA0000056138720000011.png"\; state="\{\{state\}\}">LI</figure-callout>}}^2$

For the same power level, if the same inductance value is used in both designs, the total inductance energy required for the interleaved active PFC is only half that of a single stage, i.e., one stage

$E_{\mathrm{SL}}=\frac{1}{2}{E}_{I({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="DEST\_PATH\_HDA0000056138720000011.png,DEST\_PATH\_HDA0000056138720000012.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2)}$

Compared with the existing single-stage active PFC, the staggered active PFC can reduce the total inductance energy required by the design by 50% at most.

The reduced inductive power of interleaved active PFC can reduce the magnet volume by up to 32%. Compared with a single-stage active PFC structure, the high-frequency output capacitor of the staggered active PFC has the root mean square current less than 50% of that of the high-frequency output capacitor, and the root mean square current of a large-capacity capacitor is reduced. The RMS current reduction of the high frequency boost capacitor can reduce the number of boost capacitors by up to 25%.

Conduction loss P of single-stage active PFC_CSIs composed of

P_CS＝I²R

Overall conduction loss for interleaved active PFCP_CIIs composed of

$\mathrm{PCI}={\left(\frac{I}{2}\right)}^{2}R+{\left(\frac{I}{2}\right)}^{2}R$

From the above formula

$P_{\mathrm{CI}}=\frac{1}{2}{P}_{\mathrm{CS}}$

Compared with a single-stage active PFC, the staggered active PFC can reduce the conduction loss by 50% at most.

During the operation of the single-phase CCM PFC circuit under light load and heavy load, the power factor is maintained at about 0.95.

Under the condition that 2 branches with 180-degree phase difference work alternately, the interleaved active PFC circuit can maintain the power factor to be more than 0.98 within the range of more than 700W of heavy load.

Claims (2)

1. The utility model provides a frequency conversion air conditioner alternating active PFC circuit which characterized in that: a bridge rectifier and a group of 2 power factor branches are connected in parallel at two ends of an alternating current power supply, the current input end and the current output end of the 2 power factor branches are mutually overlapped, and the phase difference of the 2 power factor branches is 180 degrees.

2. The interleaved active PFC circuit of claim 1, wherein: in each power factor branch circuit, a boosting inductor and a power IGBT are connected in series.

Images