JP2001103761A - Switching regulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching regulator capable of preventing the peaks of input currents running into a rectifying and filtering circuit from overlapping. SOLUTION: For harmonic current restraining reactors 5a, 5b provided for respective rectifying the filtering circuits 4a, 4b, by selectively and individually setting the inductance that the peaks of input currents do not overlap.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a switching regulator for adjusting power supplied to a load.

[0002]

2. Description of the Related Art Generally, a switching regulator is
It converts an alternating current into a direct current, adjusts a direct current power supply, and supplies power to an electric product as a load. That is, an alternating current from a commercial frequency AC power supply is rectified by a rectifying / smoothing circuit, and the power is adjusted by a switching control circuit so as to be supplied to an electric product as a load.

When the power consumption of an electric product is large or the output load is multi-output, a plurality of rectifying / smoothing circuits are provided after an input section of a commercial frequency AC power supply to branch off. Various power loads are connected to supply power. A harmonic current suppression reactor for suppressing a harmonic current included in the input current is provided at a stage preceding each rectifying and smoothing circuit.

[0004]

However, in such a conventional switching regulator, harmonic currents are suppressed by using a plurality of harmonic current suppression reactors provided for each rectifying and smoothing circuit. Current peaks of a plurality of harmonic current suppression reactors may overlap in phase. When the phases are the same, the current peak further increases. Therefore, in order to suppress the peak of the harmonic current, the capacity of the reactor for suppressing the harmonic current is increased. In other words, since the harmonic current suppression reactor responds by increasing the size and the inductance, there is a problem in that the component mounting area is increased due to the increase in the size and the capacity and the cost is increased.

It is an object of the present invention to provide a switching regulator in which the peaks of the input current entering the rectifying / smoothing circuit do not overlap.

[0006]

A switching regulator according to a first aspect of the present invention is provided with a plurality of switching regulators, each branching from an input section for inputting a commercial frequency AC power supply, and rectifying the AC power supply and supplying a direct current to a load. Rectifying / smoothing circuits; a plurality of switching control circuits respectively provided corresponding to the rectifying / smoothing circuits, for controlling direct current obtained by the rectifying / smoothing circuits, and adjusting power supplied to the load; A plurality of harmonic current suppressing reactors provided before the smoothing circuit and having inductance values such that peaks of input currents entering the respective rectifying and smoothing circuits do not overlap;
It is characterized by having.

The definitions and technical meanings of the terms in claims 1 and 2 are based on the following description unless otherwise specified.

A commercial frequency AC power supply is 50 Hz or 6 Hz.
It is an alternating current of 0 Hz. The rectifying and smoothing circuit includes, for example, a full-wave rectifying circuit of a diode bridge and a smoothing capacitor.
It converts an alternating current into a direct current and smoothes it. It branches off from the input part of the AC power supply and is provided in parallel with two or more. The switching control circuit operates at a predetermined high frequency,
This adjusts the DC power supplied to the load.

The harmonic current suppressing reactor is provided at the input of each rectifying and smoothing circuit, and limits the input current. As the inductance value of the harmonic current suppression reactor, a different inductance value is selected and used for each rectifying / smoothing circuit so that the input current peaks of the rectifying / smoothing circuits do not overlap. In selecting the inductance value, it is determined in consideration of the inductance and capacitance existing in the circuit.

The switching regulator according to claim 2 is
2. The switching regulator according to claim 1, wherein the plurality of harmonic current suppressing reactors include a harmonic current suppressing reactor in which a part of the plurality of rectifying and smoothing circuits are collectively installed.

There are three or more rectifying / smoothing circuits, and the number of the harmonic current suppressing reactors is smaller than the number of the rectifying circuits. A part of the rectifying / smoothing circuits is collectively provided as one harmonic current suppressing reactor. In this case, the inductance value of the harmonic current suppression reactor is also rectified so that the peaks of the input currents entering the harmonic current suppression reactor do not overlap, as in the case of the first aspect of the present invention. A phase shifter is selected and used for each smoothing circuit. Thereby, the peak value of the harmonic current is suppressed.

[0012]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a switching regulator according to a first embodiment of the present invention.

An alternating current from a commercial frequency AC power supply 1 is input to a filter circuit 3 via an input unit 2. The filter circuit 3 includes a reactor and a capacitor. Two rectifying / smoothing circuits 4a and 4b are provided at the subsequent stage of the filter circuit 3, and rectify the AC from the AC power supply 1. Each rectifying / smoothing circuit 4a, 4b has a rectifying / smoothing circuit 4
Harmonic current suppression reactors 5a and 5b for suppressing harmonic currents included in input currents entering a and b are provided.

Further, switching control circuits 6a and 6b are provided at the subsequent stage of each of the rectifying and smoothing circuits 4a and 4b, and control the direct current obtained by each of the rectifying and smoothing circuits 4a and 4b.
The power supplied to the loads connected to the transformers 7a and 7b is adjusted.

Here, the harmonic current suppressing reactor 5a,
5b is selected and used as an inductance value such that the peaks of the input currents input to the rectifying / smoothing circuits 4a and 4b do not overlap. That is, the inductance values of the harmonic current suppressing reactors 5a and 5b inserted into the rectifying and smoothing circuits 4a and 4b branched into two at the subsequent stage of the filter circuit 3 are designed for each of the rectifying and smoothing circuits 4a and 4b.

In selecting an inductance value such that the peaks of the harmonic currents do not overlap, the inductance value is determined in consideration of the inductance and capacitance of the filter circuit 3 and the stray capacitance of the circuit. As a result, the peaks of the harmonic currents do not overlap at the input portions of the rectifying / smoothing circuits 4a and 4b, so that the harmonic current suppressing circuit can be configured with a small harmonic current reactor.

Next, a second embodiment of the present invention will be described. FIG. 2 is a configuration diagram of a switching regulator according to a second embodiment of the present invention. The second embodiment differs from the first embodiment shown in FIG. 1 in that a plurality of rectifying / smoothing circuits are provided instead of providing a harmonic current suppressing reactor 5 for each rectifying / smoothing circuit 4. 4 are arranged so that one harmonic current suppressing reactor 5 is provided.

In FIG. 2, a plurality of (three) rectifying / smoothing circuits 4a, 4b and 4c are provided with a harmonic current suppressing reactor 5a corresponding to the rectifying / smoothing circuit 4a. 4b and 4c are provided with one harmonic current suppressing reactor 5b collectively.

In this case, as in the first embodiment, the harmonic current suppressing reactors 5a and 5b are
a is selected and used so that the peaks of the input currents input to the rectifying / smoothing circuits 4b and 4c do not overlap. The inductance values of the harmonic current suppression reactors 5a and 5b are determined by the rectifying and smoothing circuit 4a and the rectifying and smoothing circuit 4a.
b, 4c.

Similarly, in selecting an inductance value such that the peaks of the harmonic current do not overlap,
It is determined in consideration of the inductance and capacitance of the filter circuit 3 and the stray capacitance of the circuit. As a result, the peaks of the harmonic currents do not overlap at the input portions of the rectifying / smoothing circuits 4a and 4b, so that the harmonic current suppressing circuit can be configured with a small harmonic current reactor.

[0021]

As described above, according to the first aspect of the present invention, the value of the harmonic current suppressing reactor is selected and used so as not to overlap the current peak of the other high frequency current suppressing reactor. The suppression circuit can be provided at low cost and with a small mounting area. According to the second aspect of the present invention, in addition to the effect of the first aspect, the harmonic current suppressing reactor can be saved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a switching regulator according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a switching regulator according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Input part 3 Filter circuit 4 Rectifier smoothing circuit 5 Harmonic current suppression reactor 6 Switching control circuit 7 Transformer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G065 AA05 DA01 DA06 DA07 EA06 FA01 HA14 MA01 MA03 MA10 NA03 5H006 AA01 BB06 CA07 CB01 CC01 CC04 CC08 DA02 FA02 HA84 5H740 BA18 BB05 BB08 BC01 BC02 MM12 MM18 NN01

Claims (2)

[Claims] 1. A plurality of rectifying / smoothing circuits, each of which is provided by being branched from an input section for inputting a commercial frequency AC power supply, and rectifies the AC power supply and supplies DC to a load; A plurality of switching control circuits respectively provided to control the DC obtained by the rectifying / smoothing circuit and adjusting the power supplied to the load; and A plurality of harmonic current suppression reactors having inductance values such that the peaks of the input current entering the smoothing circuit do not overlap. 2. The switching device according to claim 1, wherein the plurality of harmonic current suppressing reactors include a harmonic current suppressing reactor in which a part of the plurality of rectifying and smoothing circuits are collectively installed. regulator.