JP2000102260A - Power converter - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the inductance of wiring, reduce the radiated magnetic field generated around the wiring, improve power efficiency, and affect the surrounding conductors (mainly the housing of the power converter). Provide a small power converter. A main circuit wiring includes a P-side wiring connecting a P terminal of a forward converter and a P terminal of an inverse converter, and
An N-side wiring 42 connects the N terminal of the forward converter 3 and the N terminal of the inverse converter 6. P-side wiring 41 and N-side wiring 4
Reference numeral 2 denotes a plate-shaped conductor (bus bar) having substantially the same thickness and width. Between the smoothing capacitor 5 and the inverter 6, the P-side wiring 41 branches into two P-side wirings 41a and 41b, and the two P-side wirings 41a and 41b sandwich the N-side wiring 42 therebetween. I have.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter comprising a forward converter, a smoothing capacitor, and an inverter, and more particularly, to reduce the inductance of a main circuit wiring between the forward converter and the inverter. The present invention relates to a power converter.

[0002]

2. Description of the Related Art A general power converter includes a forward converter (converter) for converting an AC input power supply to DC, a smoothing capacitor for smoothing the output of the forward converter, and the DC converted to a variable voltage and a variable frequency. A main circuit that connects each electrical component such as an inverter (converter) that performs conversion, control means that drives and controls these converters, and a cooling body (cooling fins, cooling fans, wind tunnel, etc.) that cools these electrical components Cooling body).

A bus bar (conductor plate) wiring is used for the main circuit wiring connecting the forward converter and the inverse converter to reduce the inductance of the wiring, and a smoothing capacitor is connected between the bus bar wirings. .

Since the amount of current flowing through the wiring between the smoothing capacitor and the inverter is large, if the inductance of the wiring is large, the jump voltage increases when the inverter performs a switching operation. When the jump voltage is large, the power loss of the power converter increases. Also, if the jump voltage is very large, the elements in the power converter may be destroyed. Further, the jump voltage waveform has a high frequency component, and generates a radiation magnetic field.

[0005] When the switching operation of the inverter is performed, a current transiently flows through the wiring, and a magnetic field fluctuating around the wiring is generated. This fluctuating magnetic field generates an eddy current in the conductor around the wiring, so the conductor around the wiring generates heat,
It contributes to power loss.

The phenomenon that occurs between the smoothing capacitor and the inverter also occurs in the snubber circuit in the converter.
The snubber circuit is a circuit composed of a capacitor connected in parallel with a diode connected in parallel with the power semiconductor element, and has a function of limiting a voltage applied to the element at the time of turn-off and a current flowing through the element at the time of turn-on. Also in this snubber circuit, if the inductance of the wiring is large, the jumping voltage becomes large at the time of the switching operation of the inverse conversion circuit, and the function cannot be exhibited. In addition, since a current also transiently flows through the wiring of the snubber circuit, a radiation magnetic field is generated around the wiring, and power is lost.

Japanese Unexamined Patent Publication No. 6-225545 describes that two plate-shaped wirings through which a reciprocating current flows are arranged close to each other in order to reduce the inductance of the wirings.

Japanese Patent Application Laid-Open No. 7-46857 describes that a plurality of plate-like wires are stacked to reduce the inductance of the wires.

[0009]

However, when a plurality of plate-like wirings are stacked as in the prior art described above, the inductance can be reduced as the wiring area is increased, but the size of the wiring is limited. Cannot sufficiently reduce the inductance.

[0010] Further, simply stacking the bus bar wiring connecting the terminals of each component cannot reduce the radiation magnetic field generated around the wiring.

SUMMARY OF THE INVENTION An object of the present invention is to reduce the inductance of a wiring, reduce a radiated magnetic field generated around the wiring, improve power efficiency, and provide conductors and the like around the main body (mainly a housing of a power converter).
To provide a power converter having a small effect on the power converter.

[0012]

A feature of the present invention that achieves the above object is that a main circuit wiring connecting a forward converter and an inverse converter has the same terminal in the forward converter and the inverse converter. The first wiring and the second wiring that connect between the terminals (for example, between the same P-pole terminals), and the terminals that are different from the terminals to which the first wiring and the second wiring are connected (for example, the N-pole terminal) Between the first wiring and the second wiring (for example, one N-side wiring is connected to two P-side wirings). Between them). A first wiring is provided between a first wiring and a third wiring of the same polarity, which connect the same terminals, compared to a conventional main circuit wiring having a structure in which two wirings having different polarities are arranged in parallel. The main circuit wiring having a structure in which a second wiring having a polarity different from that of the third wiring is sandwiched has a smaller wiring inductance, and has a shield structure by the first wiring and the third wiring having the same polarity. Therefore, the radiation magnetic field is small.

Therefore, according to the feature of the present invention, since the inductance of the main circuit wiring is small and the radiation magnetic field is small,
A jump voltage can be reduced when the inverter performs a switching operation, and power loss of the power converter can be reduced. In addition, the radiation magnetic field due to the jump voltage can be reduced, and the influence on surrounding conductors and the like (mainly the housing of the power converter) such as eddy current loss due to heat generation can be reduced.

In the snubber circuit wiring between the smoothing capacitor and the inverter, and also in the snubber circuit wiring of the inverter, the first and third wirings having the same polarity and connecting the same terminals are connected to each other. The second wiring having a different polarity from the first wiring and the third wiring.
The same operation and effect as described above can be obtained even with the structure sandwiching the wiring.

Further, a dielectric may be arranged between the first wiring and the third wiring and between the third wiring and the second wiring to insulate the three wirings. .

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A power converter according to an embodiment of the present invention will be described. First, the circuit configuration of the power converter will be described with reference to FIG.

The power converter converts an AC voltage generated by the three-phase AC power supply 1 into a variable voltage or a variable frequency power and supplies it to a load such as an induction motor 8. The power converter includes a forward converter 3 (also called a converter) for converting an AC voltage generated by the three-phase AC power supply 1 into a DC voltage, a smoothing capacitor 5 for smoothing the converted DC voltage, and a smoothed DC voltage. Is converted to a variable voltage or a variable frequency. The input converter 2 connects the three-phase AC power supply 1 and the forward converter 3 with the input wire 2, and the forward converter 3 and the inverse converter are sandwiched by the smoothing capacitor 5. 6 is connected by a main circuit wiring 4, and the inverter 6 and the induction motor 8 are connected by an output wiring 7.

The forward converter 3 is composed of a variable control element such as an IGBT, an IPM, or a power semiconductor. The forward converter 3 converts an AC voltage generated by the three-phase AC power supply 1 into a DC voltage, and converts a DC voltage into a DC voltage. When the value exceeds a certain specified value, electric power generated on the load side is regenerated on the three-phase AC power supply 1 side. When the power generated on the load side is not regenerated to the three-phase AC power supply 1 side, a diode module for performing full-wave rectification may be used instead of the forward converter 3.

The inverter 6 is composed of a variable control element such as an IGBT, IPM, or power semiconductor, and forms a snubber circuit by connecting a snubber capacitor 11 in parallel with a diode.

FIG. 1 shows a main circuit wiring 4 for connecting a smoothing capacitor 5 and an inverter 6. The main circuit wiring 4 includes a P-side wiring 41 that connects a P terminal (not shown) of the forward converter 3 and a P terminal of the inverse converter 6, and an N terminal (not shown) of the forward converter 3. N-side wiring 4 for connecting to the N terminal of the inverter 6
Consists of two. The P-side wiring 41 and the N-side wiring 42 are respectively connected to one of the two terminals of the smoothing capacitor 5 between the forward converter 3 and the inverse converter 6. The P-side wiring 41 and the N-side wiring 42 are plate-shaped conductors (bus bars) having substantially the same thickness and width.

Between the smoothing capacitor 5 and the inverter 6, the P-side wiring 41 is branched into two P-side wirings 41a and 41b, and the two P-side wirings 41a and 41b are connected between the N-side wiring 42. Sandwiched between. The dielectric plate 10 is provided between the P-side wirings 41a and 41b and the N-side wiring 42. The dielectric plate 10 electrically insulates the P-side wirings 41a and 41b from the N-side wiring 42, and also includes the P-side wirings 41a and 41b.
And the N-side wiring 42.

Next, the inductance of the main circuit wiring 4 of the power converter of this embodiment is determined. FIG. 3 shows a simplified wiring structure from the forward converter 3 to the inverse converter 6 in FIG.
FIG. 4 shows an equivalent circuit of the P-side wirings 41a and 41b and the N-side wiring 42 of FIG. In this equivalent circuit, the smoothing capacitor 5 is regarded as the power supply 17.

[0023] For simplicity, the same L ₀ the self-inductance of the P-side wiring 41a, 41b and N-side interconnect 42, P-side wiring 41a, the mutual inductance between 41b and N-side interconnect 42 M _1, P-side wiring the mutual inductance of each other and M _2. However, it is _{L 0> M 1> M 2} .

P seen from the power supply 17 (smoothing capacitor 5)
Side wiring 41a, the inductance L ₃ and 41b and N-side interconnect 42 is expressed by (Equation 1).

L ₃ = (3 × L ₀ −4 × M ₁ + M ₂ ) / 2 (Equation 1) Inductance L ₂ when two conventional bus bar wirings (N side and P side) are arranged in parallel. Is represented by (Equation 2).

L ₂ = 2 × L ₀ −2 × M ₁ (Equation 2) Comparing the inductance L ₂ of the inductance L ₃ ,
From (Equation 3), it is _{L 2> L 3> L 2} /2.

L ₃ = {L ₂ + (L ₂ + M ₂ −2 × M ₁ )} / 2 (Equation 3) Therefore, the N-side wiring 4 is smaller than the conventional two parallel wiring structure.
In the three parallel wiring structures in which 2 is sandwiched between two P-side wirings 41a and 41b, the wiring inductance is smaller.

FIGS. 5 and 6 show the cross section of the wiring and the distribution of the magnetic field lines of the radiated magnetic field generated around the cross section. FIG. 5 shows a case where two conventional wires are arranged in parallel, and FIG. 6 shows a case where three wires of this embodiment are arranged in parallel.
This is a distribution of lines of magnetic force when currents flowing in opposite directions flow through the N-side wiring 42 and the P-side wiring 41.

In the case of the conventional two parallel wiring structure shown in FIG. 5, the magnetic force lines 14 are widely distributed outward. On the other hand, FIG.
In the case of the three parallel wiring structures of the present embodiment, the number of magnetic lines of force 14 distributed outside is small. This is because the two P-side wires 41
This is because the radiated magnetic field spreading outside the P-side wirings 41a and 41b is canceled by the a and 41b, and the lines of magnetic force 14 are confined between the wirings. That is, the main circuit wiring 4 of the present embodiment has a shield structure by the two outer P-side wirings 41a and 41b.

Therefore, the three parallel wiring structures in which the N-side wiring 42 is sandwiched between the two P-side wirings 41a and 41b have smaller inductance and lower radiated magnetic field than the conventional two parallel wiring structures. Since it is small, the jump voltage can be reduced when the inverter performs a switching operation, and the power loss of the power converter can be reduced. In addition, the radiation magnetic field due to the jump voltage can be reduced, and the influence on surrounding conductors and the like (mainly the housing of the power converter) such as eddy current loss due to heat generation can be reduced.

The two P-side wirings 41a and 41b provide N
Although the case of the wiring structure sandwiching the side wiring 42 has been described, the radiated magnetic field can be similarly reduced even if the polarity is reversed.

As described above, according to the power converter of this embodiment, the inductance of the main circuit wiring 4 between the smoothing capacitor 5 and the inverter 6 is reduced, and the generation of the radiation magnetic field in the main circuit wiring 4 is reduced. Since the power consumption is reduced, the power efficiency can be improved, and the influence on surrounding conductors and the like (mainly, the housing of the power converter) can be reduced.

Although the dielectric plate 10 is used in this embodiment, the P-side wirings 41a, 41a,
If the wiring 41b and the N-side wiring 42 can be electrically insulated and arranged close to each other, the dielectric plate 10 need not be used.

Further, as shown in FIG.
5, a forward converter 3, a smoothing capacitor 5, an inverse converter 6,
Circuit components and wires constituting other power converters may be provided. Although the wiring is arranged on the printed board 15 in FIG. 7, a PN wiring may be arranged so as to sandwich the printed board instead of the dielectric plate 10.

As shown in FIG. 8, in the snubber circuit wiring connecting the snubber capacitor 11 with the diode constituting the inverter and the power semiconductor element 16, one of the snubber wirings is branched, and Snubber wiring 91
Even if a and 91b sandwich the other snubber wiring 92 therebetween, the inductance of the snubber wiring can be reduced, and the influence of the snubber wiring current on the surroundings of the fluctuating magnetic field can be reduced.

In the above description, three wiring structures in which one of the NP wirings is branched and the other wiring is branched and two wirings are sandwiched are shown.
Even in the structure in which one of the P wirings sandwiches the other, the wiring inductance and the radiation magnetic field can be reduced as in the present embodiment.

[0037]

According to the present invention, since the inductance of the main circuit wiring is small and the radiated magnetic field is small, the jumping voltage can be reduced when the inverter performs the switching operation, and the power loss of the power converter can be reduced. In addition, the radiation magnetic field due to the jump voltage can be reduced, and the influence on surrounding conductors and the like (mainly the housing of the power converter) such as eddy current loss due to heat generation can be reduced.

In the snubber circuit wiring between the smoothing capacitor and the inverter and the snubber circuit wiring of the inverter, the first wiring and the third wiring having the same polarity and connecting the same terminals are connected to each other. The second wiring having a different polarity from the first wiring and the third wiring.
The same operation and effect as described above can be obtained even with the structure sandwiching the wiring.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main circuit wiring 4 for connecting a smoothing capacitor 5 and an inverter 6;

FIG. 2 is a diagram showing a circuit configuration of the power converter according to the embodiment.

FIG. 3 is a diagram showing a simplified wiring structure from a forward converter 3 to an inverse converter 6;

FIG. 4 is a diagram showing an equivalent circuit of P-side wirings 41a and 41b and an N-side wiring 42 of FIG. 3;

FIG. 5 is a diagram showing a magnetic field line distribution when two conventional wirings are arranged in parallel.

FIG. 6 is a diagram showing a magnetic field line distribution when three wires of the present invention are arranged in parallel.

FIG. 7 is a diagram showing a power conversion device using a printed circuit board 15.

FIG. 8 is a diagram showing a snubber circuit wiring structure.

[Explanation of symbols]

1: three-phase AC power supply, 2: input wire, 3: forward converter, 4:
Main circuit wiring, 5 ... smoothing capacitor, 6 ... inverter, 7 ...
Output wiring, 8: induction motor, 10: dielectric plate, 11: snubber capacitor, 14: magnetic field line, 15: printed circuit board,
16: diode and power semiconductor element, 17: power supply,
41, 41a, 41b ... P side wiring, 42 ... N side wiring, 9
1a, 91b, 92 ... snubber wiring.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kiyoji Komatsu 1070 Ma, Hitachinaka-shi, Ibaraki F-term in Mito Plant, Hitachi, Ltd. BB10 BC06 PP02 PP03

Claims (4)

[Claims] A forward converter for rectifying an alternating current to convert it to a direct current voltage; a smoothing capacitor for smoothing an output of the forward converter;
In a power converter including a reverse converter for converting a DC voltage obtained from the smoothing capacitor into an AC, and a main circuit wiring connecting between the forward converter and the reverse converter, the main circuit wiring is A first wiring and a second wiring connecting between the same terminals of the converter and the inverse converter, and terminals different from terminals connected to the first wiring and the second wiring are connected. A power converter, comprising a third wiring, wherein the third wiring is arranged between the first wiring and the second wiring. 2. A forward converter for rectifying an AC and converting it to a DC voltage, a smoothing capacitor for smoothing an output of the forward converter,
In a power converter including a reverse converter for converting a DC voltage obtained from the smoothing capacitor into an alternating current, and a main circuit wiring for connecting between the forward converter and the reverse converter, the main circuit wiring includes: A first wiring connecting between a capacitor and the same terminal of the inverter;
And a third wiring connecting between terminals different from the terminals to which the first wiring and the second wiring are connected. The third wiring includes the first wiring and the third wiring. A power converter, wherein the power converter is disposed between the power converter and the second wiring. 3. A forward converter for rectifying an AC and converting it to a DC voltage, a smoothing capacitor for smoothing an output of the forward converter,
In a power converter including a reverse converter for converting a DC voltage obtained from the smoothing capacitor into an AC, and a snubber circuit wiring for connecting between a diode in the reverse converter and a snubber capacitor, the snubber circuit wiring includes: A first wiring and a second wiring connecting between the same terminals of the diode and the snubber capacitor, and a third wiring connecting between terminals different from the terminals connected to the first wiring and the second wiring. The power converter, wherein the third wiring is disposed between the first wiring and the second wiring. 4. A method according to claim 1, wherein said first wiring and said third wiring are arranged between said first wiring and said third wiring.
4. A dielectric is disposed between the third wiring and the second wiring.
Power converter.