JPH10201221A - Converter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a converter device that enables the reduction of power supply harmonic current and the improvement of power factor, and is small-sized and inexpensive with less electromagnetic noise generated. SOLUTION: A reactor 103 is inserted into the phase-R input and phase-T input of a capacitor-smoothing rectifier circuit in single-phase input. The reactor 103 is electrically insulated between phase R and phase T, and magnetically independent. Or, the reactor 103 is magnetically coupled so that inductance is produced preferentially in the normal mode. Or, the reactor 103 is magnetically coupled so that inductance is produced both in the normal mode and in the common mode. A noise filter is inserted in either or both of the input and output of the reactor 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a converter device.

[0002]

2. Description of the Related Art Conventionally, AC input is rectified by a diode,
There is a converter device that obtains a DC output by smoothing with a capacitor.

FIG. 10 is a diagram showing a conventional converter device. In the figure, 1001, 1002, 1003, 100
4 is a diode and 1005 is a smoothing capacitor. Diodes 1001 and 1002, 1003 and 1004 are respectively connected in series. These two connection points are AC inputs 1006 and 1007, respectively, and are connected to a single-phase AC power supply. Also, a diode 1001 connected in series
, 1002, 1003 and 1004 are both connected in parallel with the smoothing capacitor 1005. The connection points are the DC outputs 1008 and 1009, and the load is connected.

[0004]

In a conventional converter device, an AC input is rectified by a diode, and stored and smoothed by a capacitor to obtain a DC output. Therefore, an input current flows during a period when the voltage of the smoothing capacitor, that is, the DC output voltage is lower than the AC input voltage.

This input current flows in a short period when the DC output voltage becomes lower than the AC input voltage, and flows later than the AC input voltage, so that the power factor is reduced.

Further, since the current flows for a short period of time, the input current does not become the same sine wave as the AC input voltage but becomes spire. The steeple input current includes a power supply harmonic current that is a frequency component that is a positive multiple of the fundamental frequency. This power supply harmonic current causes various failures to other devices via the commercial power supply.

On the other hand, the load of the converter device often includes a switching circuit that generates electromagnetic noise. For this reason, it is necessary to provide a new noise filter for suppressing electromagnetic noise on the power receiving side, that is, on the input side of the converter device, which leads to an increase in size and cost of the entire device.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce power supply harmonic current and improve power factor, and to be small and inexpensive.
An object of the present invention is to provide a converter device that achieves low electromagnetic noise.

[0009]

In the converter device of the present invention, a reactor is inserted into each of the R-phase and T-phase inputs of a rectifier circuit of a capacitor smoothing type with a single-phase input. In the reactor, the R phase and the T phase are electrically insulated, and are magnetically independent. Alternatively, the reactor is magnetically coupled such that the R-phase and the T-phase are electrically insulated and preferentially produce normal mode inductance. Alternatively, the reactor is R
The phase and the T phase are electrically insulated and are magnetically coupled so as to generate inductance in both the normal mode and the common mode. Then, if necessary, a noise filter is inserted into one or both of the input and output of the reactor.

In the converter device having the above-described configuration, the reactors inserted into the respective inputs of the R phase and the T phase increase the conduction width of the input current, reduce the power supply harmonic current, and improve the power factor. In addition, both normal mode and common mode electromagnetic noise are suppressed. This makes it possible to reduce the power supply harmonic voltage and electromagnetic noise and to improve the power factor. In addition, the amount of attenuation required for the noise filter can be reduced, and the size and cost of the converter device can be reduced at the same time.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. In the figure, 101 is a load including a switching circuit, 102 is a single-phase input, capacitor smoothing converter, 103 is a reactor, and 104 is an AC power supply.

The output of the converter 102 is connected to a load 101, and the input is a reactor 103 whose R and T phases are electrically insulated and magnetically independent.
Is connected to the AC power supply 104 via the.

The converter 102 rectifies the AC input with a diode, accumulates and smoothes the AC input with a capacitor, and outputs DC. Further, the input current of the converter 102 tends to flow spontaneously in a spike-shape during a short period when the voltage of the capacitor, that is, the DC output voltage becomes lower than the AC input voltage.

The reactor 103 plays a role of extending the period (conduction width) during which the spike-shaped current flows by the sum of the energy stored in the R-phase and T-phase inductances. As a result, the power factor is improved and the power supply harmonic current is suppressed.

The reactor 103 has an R phase and a T phase.
Because it is inserted in the phase, the noise mainly transmitted from the load 101 including the switching circuit is not only the noise component of the normal mode flowing in the R phase and the T phase, but also the R component.
It is also possible to suppress a common mode noise component that is transmitted in phase to the phase and the T phase.

Here, even if the reactor is inserted into one of the R and T phases, it is possible to improve the power factor and suppress the power supply harmonic current flowing between the R and T phases and the normal mode noise. It is. However, only one phase has an effect on the common mode noise, and it is impossible to suppress the common mode noise of the other phase. Therefore, by inserting the reactor 103 into the R phase and the T phase, it is possible to suppress common mode noise.

In particular, reactor 103 has an R phase and a T phase.
If the phase inductance is obtained from a magnetically independent core, the magnetic flux generated in both cores will not cancel out the common mode noise component, and the same inductance as the normal mode will be obtained. improves.

At this time, if the R-phase and T-phase inductances are set to different values, the impedance of each phase is different, and a part of the common mode noise induces the normal mode noise. Therefore, this can be avoided by setting the inductance of the reactor 103 so that the R-phase and the T-phase have the same value.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention. In the drawing, reference numeral 203 denotes a reactor in which the R phase and the T phase are electrically insulated and magnetically coupled so as to preferentially generate normal mode inductance.

The output of the converter 102 is connected to a load 101, and the input is a reactor 20 for both the R and T phases.
3 and connected to an AC power supply 104.

As in the first embodiment, the converter 102
Rectifies the AC input with a diode, accumulates and smoothes it with a capacitor, and outputs a DC. The converter 102
Input current tends to flow spontaneously in a spike in a short period of time when the voltage of the capacitor, that is, the DC output voltage becomes lower than the AC input voltage.

The reactor 203 plays a role in extending the period (conduction width) during which the spike-shaped current flows by the sum of the energy stored in the R-phase and T-phase inductances. As a result, the power factor is improved and the power supply harmonic current is suppressed.

In addition, reactor 203 suppresses normal mode noise flowing in the R and T phases.

The reactor 203, which is magnetically coupled so as to preferentially generate normal mode inductance, can be obtained, for example, by differentially winding R-phase and T-phase wires on a common core. Can be

At this time, the inductance of each phase of the R phase and the T phase is about one half of the inductance obtained from the magnetically independent core due to the mutual inductance. This corresponds to √ of the number of turns and 1/2 of the cross-sectional area of the core, and the reactor 203 can be significantly reduced in size.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention. In the figure, reference numeral 303 denotes a reactor in which the R phase and the T phase are electrically insulated and magnetically coupled so as to generate inductance in both the normal mode and the common mode.

The output of converter 102 is connected to load 101, and the input is connected to reactor 30 for both the R and T phases.
3 and connected to an AC power supply 104.

As in the first embodiment, the reactor 303
Can improve the power factor and suppress the power supply harmonic current and the normal mode noise by the sum of the energy stored in the R-phase and T-phase normal mode inductances.

In addition, the reactor 303 can suppress the common mode noise by the common mode inductance.

FIG. 4 shows an embodiment of a reactor in which inductance can be obtained in both the common mode and the normal mode. In the figure, 401 and 402 are R-phase windings Lnr and Lc
r, 403 and 404 are T-phase windings Lnt and Lct, 40
5 is a ferrite core, and 406 is a silicon steel sheet core.

The windings Lnr401 and Lnt403 are differentially wound and generate an inductance with respect to a normal mode current. Further, the windings Lcr402 and Lct40b are wound in the same phase and generate inductance in a common mode. And
These windings are wound around a common ferrite core 405 and a silicon steel sheet core 406 and are magnetically coupled.

Windings Lnr401 and Lnt403, Lcr
If 402 and Lct 404 have the same number of turns, respectively,
For the current flowing through the R and T phases, Lcr 402
And the magnetic fluxes generated in Lct 404 cancel each other out, and Ln
Only r401 and Lnt403 generate inductance.
In addition, Lnr4
01 and the magnetic flux generated in Lnt 403 cancel each other out,
Only Lcr402 and Lct404 generate inductance.

Thus, in the reactor of this embodiment,
Inductance can be obtained in both the common mode and the normal mode.

A common core is a ferrite core 405.
And the silicon steel core 406 as a hybrid,
The frequency characteristics of each core can be realized, and an inductance having a wide frequency band can be obtained.

FIG. 5 is a diagram showing a fourth embodiment of the present invention. In the figure, reference numeral 501 denotes a noise filter.

The output of the converter 102 is connected to the load 101, and the input is the reactor 10 for both the R and T phases.
3 and the AC power supply 1 through the noise filter 501 in order.
04.

Here, in the figure, the noise filter 501 and the reactor 103 are connected to the AC power supply 105 in this order. However, the reactor 103 and the noise are changed according to the power supply impedance and the load impedance, and the required noise attenuation. The order of the filters 104, or
Noise filter 104, reactor 103, and second
Are connected to the AC power supply 105 in the order of the noise filter (not shown).

The noise filter 501 is connected to the reactor 10
3 removes mainly high-frequency noise, which is not sufficient by the noise suppression effect alone. Therefore, the dependency of the noise filter on the noise filter is reduced, and the number of elements and constants constituting the noise filter can be reduced.

Although there are various circuit configurations of the noise filter 501, the common mode choke coil Lc, the X capacitor Cx for shunting the R phase and the T phase, and the Y capacitor between each phase and the ground are used here to reduce the amount of attenuation. It is composed of a capacitor Cy. The Y capacitor Cy is set irrespective of the presence or absence of the reactor 103 in order to effectively utilize the upper limit of the leakage current. However, the X capacitor Cx and the common mode choke coil Lc need only have a value of about 1/10, 1/2, respectively, of the circuit configuration in which the reactor 103 is not inserted. Therefore, the size of the noise filter 501 can be reduced.

The noise suppressing effect due to the presence or absence of the reactor 103 will be described in detail with reference to one design example.

FIG. 6 is an equivalent circuit of FIG. 5 for common mode noise. In the figure, 601 is the impedance Zs of the AC power supply. 602 is the inductance Lc of the common mode choke coil. 603 is a parallel capacitance Cy of the R-phase and T-phase Y capacitors. 604 is a common mode inductance Ln of the reactor. 605 is the impedance Zr of the noise source. 606 is a noise source Vn.

For a noise source of frequency f and voltage Vn, Z
Attenuation is obtained by expressing the voltage V between terminals of s in decibels;
Assuming −20 Log (V / Vn), the attenuation of the present equivalent circuit is given by the following equation.

[0044]

-20Log (V / Vn) =-20Log (Zs) + 20Log [Zs + ωLc + {ωCy (Zs + ωLc) +1} (ωLn + Zr)] (Formula 1) where ω = 2πf.

Next, FIG. 7 shows the relationship between the amount of attenuation and the frequency obtained from equation (1). In the figure, for the sake of comparison, the case where no reactor is inserted, that is, the relationship when Ln = 0, is simultaneously indicated by a dotted line.

Here, Zs changes depending on conditions such as a place where the apparatus is connected. Therefore, using the common mode value of the pseudo power supply network used in each standard, Zs = 25Ω
And Zr also varies depending on the load connected, but assuming a parasitic capacitance between the load and the ground, Zr = 2n
F is the capacitive impedance. Each of the other elements has Lc = 3 mH, Cy = 10 nF,
Ln = 2.5 mH, an ideal element, and frequency dependence is not considered. Further, the capacitance and the inductance parasitic to each element and the wiring are neglected. For this reason, in the figure, the attenuation increases as the frequency increases, but actually the attenuation decreases from around ten and several MHz.

However, as shown in the figure, the insertion of the reactor greatly increases the attenuation. At 10 MHz, the difference is about 10%.
It can be seen that 0 dB is also present.

FIG. 8 is an equivalent circuit of FIG. 5 for normal mode noise. In the figure, reference numeral 801 denotes an inductance Lco of a common mode choke coil with respect to a normal mode current. 802 is the capacitance Cx of the X capacitor. 803
Is a normal mode inductance Ln of the reactor.

The amount of attenuation of this equivalent circuit is as follows.

[0050]

-20Log (V / Vn) =-20Log (Zs / 2) + 20Log [Zs + 2ωLco + {ωCx (Zs + 2ωLco) +1} (2ωLn + Zr)] (Equation 2) Relationship between attenuation amount and frequency obtained from the above equation Is shown in FIG. In the figure, for comparison, when no reactor is inserted,
That is, the relationship at the time of Ln = 0 is simultaneously shown by the dotted line.

Also in this case, Zs changes depending on conditions such as a place where the apparatus is connected. Therefore, using the value of the normal mode of the pseudo power supply network used in each standard, Zs = 1
00Ω. Zr also changes depending on the connected load. However, assuming a parasitic capacitance in the load, Zr = 2n
F is the capacitive impedance. Since the common mode choke coil cancels out the magnetic fluxes generated with respect to the normal mode current, the inductance Lco of the small value of the leakage magnetic flux is set to Lco = 20 nH. And
Each of the other elements has Cy = 10 nF and Ln =
It is an ideal element of 2.5 mH, and frequency dependence is not considered. Further, the capacitance and the inductance parasitic to each element and the wiring are neglected. For this reason, in the figure, the attenuation increases as the frequency increases, but actually the attenuation decreases from around ten and several MHz.

However, as is apparent from the figure, when no reactor is inserted, only about 5 dB of attenuation is obtained up to around 10 MHz, whereas when a reactor is inserted, the attenuation increases with the frequency. It can be seen that the amount greatly decreases. And, at 10 MHz, the difference is 1
It can be seen that an attenuation exceeding 00 dB can be obtained. As described above, according to the present invention, the reactor is changed to the R phase and the T phase.
It can be seen that the power supply harmonic current of the capacitor smoothing type rectifier circuit can be suppressed, the power factor can be improved, and the electromagnetic noise can be suppressed by inserting it into each phase input. . Further, it can be seen that the noise suppression effect of the reactor reduces the amount of attenuation of the noise filter, thereby making it possible to reduce the size and cost of the noise filter and, consequently, to reduce the size and cost of the converter device.

[0053]

According to the present invention, by inserting a reactor into each of the R-phase and T-phase inputs, the power supply harmonic current of the capacitor smoothing type rectifier circuit can be suppressed, the power factor can be improved, and the power factor can be improved. Noise can be suppressed.
In addition, the noise suppression effect of the reactor reduces the amount of attenuation of the noise filter, thereby making it possible to reduce the size and cost of the noise filter. Furthermore, the reactor itself can be reduced in size by constituting the reactor with a magnetically coupled core.

For this reason, in particular, the power supply harmonic current is small,
The present invention is useful for a converter device requiring a high power factor, low electromagnetic noise, small size and low cost.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an embodiment of a reactor in which inductance is obtained in both the common mode and the normal mode.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention.

6 is an equivalent circuit diagram for the common mode in FIG.

FIG. 7 is a circuit diagram showing the effect of attenuating common mode noise depending on the presence or absence of a reactor.

8 is an equivalent circuit diagram for the normal mode in FIG.

FIG. 9 is a circuit diagram showing an attenuation effect of normal mode noise depending on the presence or absence of a reactor.

FIG. 10 is a circuit diagram showing a conventional converter.

[Explanation of symbols]

101: load, 102: converter, 103: reactor, 104: AC power supply.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kenji Kubo 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd.

Claims (5)

[Claims] 1. A converter device wherein a reactor is inserted into each of the R-phase and T-phase inputs of a rectifier circuit of a capacitor smoothing type with a single-phase input. 2. A reactor is inserted into each of the R-phase and T-phase inputs of a rectifier circuit of a capacitor smoothing type with a single-phase input. The converter device is also independent. 3. A reactor is inserted in each of the R-phase and T-phase inputs of a single-phase input, capacitor-smoothing type rectifier circuit. A converter device which is magnetically coupled so as to preferentially generate inductance. 4. A reactor is inserted in each of the R-phase and T-phase inputs of a single-phase input, capacitor-smoothing type rectifier circuit. A converter device characterized by being magnetically coupled so as to generate an inductance with a common mode. 5. A reactor having a single-phase input, a reactor inserted into each of the R-phase and T-phase inputs of the capacitor smoothing rectifier circuit, and a noise filter inserted into one or both of the input and output of the reactor. A converter device characterized by the above-mentioned.