JPH11144982A - Choke coil and rectifying/smoothing circuit using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase an inductance value in a small current region compared with that in a large current region, by providing a choke coil with a core having an air gap in a magnetic path and a winding wound around the core, and by making size of a void ununiform in accordance with a current flowing through the winding. SOLUTION: An AC current 11, a rectifying/smoothing circuit 31, six switching elements, an inverter 15 and a motor 16 are provided. The circuit 31 includes a bridge type rectifying circuit 12, a choke coil 13 and a smoothing capacitor 14. The coil 13 has a winding 18 wound around a core 17 that is formed by laminating silicon steel plates, and also has a void 20 along a magnetic path of magnetic fluxes 19 that are generated when a current flows through the winding 18. The void 20 is made ununiform with respect to the cross-sectional area of the magnetic path of the core 17. As a result of this construction, an inductance value in a small current region is increased compared with that in a large current region, and the harmonics of the power supply particularly at a low load can be reduced and the magnitude of the harmonics of the power supply per input power under low load conditions is controlled while suppressing the shape, weight and cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a choke coil and a rectifying / smoothing circuit for rectifying and smoothing an alternating current into a direct current, and used in an apparatus for home use or the like.

[0002]

2. Description of the Related Art Conventionally, a choke coil of this type and a rectifying / smoothing circuit using the same are as shown in FIG. In the figure, the rectifying and smoothing circuit is 100 volts 5
An AC power supply 1 having a sine wave voltage waveform of 0 to 60 Hz,
A bridge-type rectifier circuit 2 composed of four silicon diodes, a choke coil 3, a smoothing capacitor 4 composed of an electrolytic capacitor, and an inverter 5 composed of six switching elements for converting a DC voltage into a three-phase AC. , And a three-phase motor 6 connected to its output.

Here, the choke coil 3 is formed by winding a winding 8 of an enamel wire around an iron core 7 laminated with a silicon steel sheet, and in the middle of a magnetic path through which a magnetic flux 9 generated when a current flows through the winding 8. An air gap 10 is provided.

The gap 10 is 3 mm, which is uniform with respect to the sectional area of the magnetic path of the iron core. FIG. 5 shows the characteristics of the choke coil 3, in which the horizontal axis represents the DC current superimposed value and the vertical axis represents the inductance value.

When the direct current superimposed value is 0, the inductance value is 4 mH.
Up to approximately flat inductance value,
At A, the magnetic flux density of the iron core 7 becomes about 1.5 Tesla, and at a current value higher than that, the inductance value decreases rapidly due to the magnetic saturation of the iron core 7.

With the above configuration, when operating the motor 6, the output voltage of the AC power supply 1 is rectified by the rectifier circuit 2, and the almost complete DC voltage with small ripple is output by the choke coil 3 and the smoothing capacitor 4. Both ends of the smoothing capacitor 4 are supplied to the inverter 5.

Here, since the smoothing capacitor 4 tends to be intensively supplied near the peak phase of the AC power supply 1, the peak value is reduced by inserting the choke coil 3, and 1 has the effect of reducing the harmonic components of the current supplied from 1.

By supplying the inverter 5 with an almost perfect DC voltage having a small ripple, the inverter 5
The motor 6 can be driven well.

[0009]

As shown in FIG. 5, in the power generating apparatus having the above-mentioned configuration, the inductance value is secured to approximately 4 mH in a region where the peak value of the current flowing through the choke coil 3 is up to 15 A. Therefore, the choke coil 3 is almost 4 in the range of the condition of the full-power operation where the input power reaches 800 W from the light load condition to the power generation device.
A constant value of mH is secured.

However, regarding the harmonic components of the current supplied from the AC power supply 1, the third and fifth harmonic components, especially when the input power is a light load such as about 60 W and the absolute value is at full power, Although lower, the value obtained by dividing the harmonic component by the input power tends to increase.

In the future, in order to reduce the influence of harmonics on the power supply system, it will be important to reduce power supply harmonics per input power for each electric device. It is necessary to improve the point that the value obtained by dividing the harmonic by the input power at a light load becomes large.

However, in order to solve the problem at the time of light load with the conventional configuration, the inductance value of the choke coil 3 needs to be set to a considerably large value of about 7 mH. In order to suppress magnetic saturation, the shape, weight,
There has been a problem that the cost becomes very large, and the shape, weight, and price of the device also become large.

[0013]

In order to solve the above-mentioned problems, a choke coil according to the present invention includes an iron core having an air gap in a magnetic path, and a winding wound on the iron core, wherein the air gap is:
In order to obtain a predetermined inductance according to the value of the current flowing through the winding, the size of the winding is made non-uniform.

[0014]

The invention according to claims 1, 2 and 3 includes an iron core having a gap in a magnetic path, and a winding wound around the core, and the gap flows through the winding. By making the size non-uniform in order to obtain a predetermined inductance according to the current value, the inductance value in the small current region can be made larger than that in the large current region.

According to a fourth aspect of the present invention, the use of the choke coil of the first aspect in a rectifying / smoothing circuit reduces the power supply harmonics, especially at light load, while suppressing the shape, weight and cost. This suppresses the magnitude of power supply harmonics per input power under load conditions.

[0016]

Embodiments of the present invention will be described below. FIG. 1 shows an embodiment of claims 1 and 2.
FIG. 1 is a circuit diagram of a power generating device configured using a rectifying and smoothing circuit using a choke coil according to an embodiment of the present invention.

The power generator of FIG.
It comprises an AC power supply 11 of 60 Hz, a rectifying / smoothing circuit 31, six switching elements, an inverter 15 for converting a DC voltage into a three-phase AC, and a three-phase motor 16 connected to its output. .

Here, the rectifying / smoothing circuit 31 comprises a bridge-type rectifying circuit 12 composed of four silicon diodes, a choke coil 13, and a smoothing capacitor 14 composed of an electrolytic capacitor.

The choke coil 13 is formed by winding a winding 18 of an enameled wire around an iron core 17 laminated with a silicon steel sheet.
An air gap 20 is provided in the middle of a magnetic path through which a magnetic flux 19 generated when a current flows through the winding 18.

In the present embodiment, the air gap 20 is not uniform with respect to the cross-sectional area of the magnetic path of the iron core, and is about
/ 5 is 1 mm, and 3 mm in other parts
And

FIG. 2 shows another embodiment.
The configuration is similar to that of FIG. 1 except that the configuration of the choke coil 21 is slightly different. In FIG. 2, the gap 22 is 1
It is configured to change continuously to about 3 mm.

FIG. 3 shows the characteristics of the choke coil 13 and the choke coil 21. The abscissa represents the direct current superimposed value, and the ordinate represents the inductance value.
a is the characteristic of the choke coil 13, b is the choke coil 2
This shows the characteristic of No. 1.

As shown in FIG. 3, the choke coil 13 shown in FIG.
Since the magnetic flux concentrates on the portion of m, the inductance value is 7.5 mH. However, if it exceeds 2A, the magnetic flux density in the 1 mm portion of the gap 20 becomes about 1.6 Tesla, causing magnetic saturation, and the magnetic flux turns to the portion in which the gap 20 is 3 mm. Therefore, the inductance value is almost 4
mH, which is maintained up to 14A.

On the other hand, in the choke coil 21 shown in FIG. 2, since the air gap 22 changes continuously, the magnetic saturation is also reduced.
Occur sequentially from a small portion to a large portion, so that the characteristic becomes gentle as seen in b. In both of a and b, compared with the characteristic c of the conventional choke coil,
The inductance value becomes large in the small current range, and the magnitude of the harmonic current per input power at light load can be suppressed to a value equivalent to that of full power operation, thereby reducing the problem of harmonics in the commercial power supply system. Can be solved.

In this embodiment, although the inductance value can be increased in a small current region, the inductance value in a large current region is not increased.
The shape, weight and cost of the choke coil can be reduced.

In FIG. 1, a C-shaped silicon steel plate is used, a step of 1 mm and 3 mm is provided, and a plurality of these are stacked to constitute the iron core 17, so that a single die is used. An excellent effect that a silicon steel plate is punched out is obtained.
mm may be configured to have a step in the thickness direction.

Also, in FIG. 2, the size of the gap may be sequentially changed in the stacking direction.

In any case of the input current, the curve 22 of FIG. 2 may be optimally designed so that the inductance value required for the choke coil can always be ensured.

Further, the iron core is not limited to the C type, but may be an EE type or an EI type.

Further, in each embodiment, a rectifier circuit for performing full-wave rectification is used. However, it is not always necessary to perform full-wave rectification. For example, partial rectification or double voltage rectification may be used. Further, the choke coil is not limited to the choke coil inserted on the output side of the current circuit, and the choke coil of the present embodiment can be inserted on the input side of the rectifier circuit, that is, on the AC side.

In any case, the current flowing through the choke coil becomes small when the load is light, and a large inductance value is obtained at that time. Therefore, the effect that the harmonic current component per input power can be suppressed is obtained. What you get is no different.

The load connected to the output of the rectifying / smoothing circuit is an inverter for driving the motor in each embodiment. However, the present invention is not limited to this, and the load is operated by inputting a DC voltage. Anything may be used.

[0033]

As described above, the first, second, and third aspects of the present invention include an iron core having an air gap in a magnetic path, and a winding wound on the iron core. By making the magnitude non-uniform in order to obtain a predetermined inductance according to the current value flowing through the wire, it is possible to provide a choke coil in which the inductance value in a small current region is larger than that in a large current region. is there.

According to a second aspect of the present invention, a rectifying / smoothing circuit is formed by using the choke coil according to the first aspect of the present invention. This reduces the number of waves and suppresses the magnitude of power supply harmonics per input power under light load conditions.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a power generator using a rectifying and smoothing circuit according to an embodiment of the present invention.

FIG. 2 is another circuit configuration diagram of the power generator.

FIG. 3 is a diagram showing a direct current superposition characteristic of a choke coil used in the rectifying and smoothing circuit.

FIG. 4 is a circuit configuration diagram of a power generation device using a rectifying and smoothing circuit in a conventional example.

FIG. 5 is a diagram showing a direct current superposition characteristic of a choke coil used in the rectifying and smoothing circuit.

[Explanation of symbols]

 17 Iron core 18 Winding 20 Air gap 19 Magnetic flux

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI H02M 7/06 H01F 27/24 H

Claims (4)

[Claims] An iron core having an air gap in a magnetic path, and a winding wound around the iron core, wherein the air gap has a size to obtain a predetermined inductance corresponding to a current value flowing through the winding. Choke coil that becomes uneven. 2. The choke coil according to claim 1, wherein the air gap has a nonuniform size so as to obtain a predetermined inductance corresponding to a region of a current value flowing through the winding. 3. The choke coil according to claim 1, wherein the air gap has a non-uniform size so as to continuously obtain inductances having different sizes according to a current value flowing through the winding. 4. A rectifying / smoothing circuit using the choke coil according to claim 1.