JP2587542Y2 - Power converter - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a power converter,
More particularly, the present invention relates to a power conversion device in which the arrangement of a main circuit protection current detector and a circuit breaker mounted between a DC smoothing capacitor of a smoothing capacitor series circuit and a power transistor of an inverter unit in a power conversion device is improved.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional power converter. In the figure, reference numeral 1 denotes a commercial power supply, and 2 denotes a converter unit, which converts alternating current input from the commercial power supply 1 into direct current. Reference numeral 3 denotes a smoothing capacitor for smoothing the DC output from the converter unit 2. Reference numeral 4 denotes an inverter, which reversely converts the DC smoothed by the smoothing capacitor 3 into an AC having a predetermined voltage and frequency. When the inverter unit 4 outputs an alternating current of a predetermined voltage and frequency and the induction motor 5 is operated, when a discharge current flows from the smoothing capacitor 3 to the inverter unit 4, a current detector 6 for detecting the discharge current And a protection circuit breaker 7 for the inverter unit. Reference numeral 8 denotes a main circuit voltage detection circuit,
And the control circuit of the device determines whether the main circuit voltage is excessive or insufficient.

FIG. 5 is a front view of the conventional power converter shown in FIG. 4, and FIG. 6 is a bottom view of FIG. 5, which show the wiring structure from the smoothing capacitors 11 to 16 to the power transistor 17 of the inverter. Is shown. FIG. 5 shows an example in which the smoothing capacitors 11 to 13 and 14 to 16 are connected in series and used for a high voltage. The power transistor 17 of the inverter section fixed to the cooling body 18 and the smoothing capacitors 11 to 13 are used. Are connected to each other by bar conductors 19 and 20. The current detector 21 is connected to the bar conductors 19 and 2.
Fixed by 0 and mounted. With such a configuration, the smoothing capacitors 11 to 13 and the power transistor 17
When the current detector 21 for protecting the main circuit is attached between the power supply circuits, the wiring from the smoothing capacitors 11 to 13 to the power transistor 17 of the inverter unit becomes long, and it is difficult to reduce the size of the main circuit structure in the structure. The device itself becomes large. Also, if the wiring from the smoothing capacitors 11 to 13 to the power transistor 17 becomes long, the bar conductor 1
Since the inductance of the switches 9 and 20 increases, the surge voltage at the time of switching increases, and the snubber circuit and the like for breathing the surge voltage become complicated, and as a result, the main circuit structure increases. 4 and 5, the circuit breaker 22 for protecting the main circuit is mounted in addition to the current detector 21. The terminal 24 is connected to the + side of the converter unit,
Is connected to the negative side of the converter section. 5 and 6, parts other than the wiring of the smoothing capacitor and the power transistor are omitted.

[0004]

The conventional power converter has a structure in which a current detector and a circuit breaker for protecting a main circuit are mounted between bar conductors from a smoothing capacitor to a power transistor as described above. Therefore, the distance from the smoothing capacitor to the power transistor is long. Therefore, when the rated capacity of the power converter increases, the components themselves such as the power transistor and the smoothing capacitor also increase, and the connecting bar conductor also increases in proportion to the current value. become. Under the above conditions, if the current detector and the circuit breaker are connected between the smoothing capacitor and the power transistor, the bar conductor becomes longer, the inductance of the bar conductor increases, and the surge voltage during switching tends to increase. It is in. Therefore, a power transistor protection circuit such as a snubber circuit that absorbs surge voltage during switching,
There is a problem that it becomes complicated and expensive.

Therefore, an object of the present invention is to make the wiring distance between the smoothing capacitor and the power transistor as short as possible.
Moreover, an object of the present invention is to provide a power conversion device having a reduced external dimension.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, a converter for converting an AC input into a DC is connected to the converter, and the converter is connected to an output. A smoothing capacitor series circuit composed of two or more smoothing capacitors for smoothing a direct current, and connected to the smoothing capacitor series circuit via a bar conductor to convert the DC smoothed by the smoothing capacitor series circuit to a predetermined voltage and frequency. An inverter unit comprising a power transistor for converting back to alternating current, wherein the inverter unit, a protection current detector for the converter unit, and a circuit breaker are provided between the smoothing capacitors constituting the smoothing capacitor series circuit. Is provided.

Further, in the invention according to claim 2,
2. The power converter according to claim 1, wherein an insulator is wound around a bar conductor connecting each smoothing capacitor of the series circuit of the smoothing capacitor and the power transistor of the inverter unit, and furthermore, the bar conductors in the direction of canceling magnetic flux are brought into close contact with each other. It is a feature.

[0008]

According to the first aspect of the present invention, there is provided a power converter.
By mounting the current detector and the circuit breaker in the middle of the series-connected smoothing capacitors, it is possible to connect the smoothing capacitors of the series circuit of the smoothing capacitors directly to the power transistors of the inverter section with bar conductors. Therefore,
The distance between the bar conductors connecting the smoothing capacitor and the power transistor is the shortest.

In the power conversion device according to the present invention, an insulating material is wound around a bar conductor from each smoothing capacitor to the power transistor, and the bar conductors that cancel out magnetic flux are brought into close contact with each other, so that the wiring structure space is reduced. And reduce the inductance of the bar conductor.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to the drawings.

FIG. 1 is a front view showing a power converter according to an embodiment of the present invention, and FIG. 2 is a bottom view of FIG. 1, showing a wiring structure from a smoothing capacitor to a power transistor in an inverter section. In FIGS. 1 and 2, a cooling body 18 in which a power transistor 17 is closely contacted for cooling is shown in FIG.
Similarly, it is arranged on one side of the power converter. The current detector 21 and the circuit breaker 22 attached to the conventional power converter are connected to the smoothing capacitors 11 to 13 connected in series.
And between 14 and 16 via a bar conductor,
The smoothing condensers 11 to 13 and 14 to 16 are
8 can be arranged adjacent to the first embodiment. The smoothing capacitors 11 to 13 and the power transistor 17 are connected to a bar conductor 19.
And the smoothing capacitors 14 to 16 are connected to the bar conductor 20.
Connected.

With the above configuration, as compared with the power converter shown in FIG. 5, in this embodiment, the current detector 21 and the circuit breaker 22 are replaced by the smoothing capacitors 11 to 13 and the power transistor 1
7, the smoothing capacitors 11 to 16 can be connected to the power transistor 17 by the bar conductors 19 and 20. Therefore, the bar conductors 19 and 20 connecting the smoothing capacitors 11 to 16 and the power transistor 17 are connected.
Can be shortened, and the inductance of the bar conductors 19 and 20 due to the wiring can be made smaller than the conventional structure shown in FIG.

Further, an insulator 23 is provided on the bar conductors 19 and 20.
(Flow coating is applied), the bar conductors that cancel each other out of the magnetic flux are brought into close contact with each other, and the magnetic fluxes cancel each other out, whereby the inductance can be reduced. Therefore, the surge voltage at the time of switching can be suppressed, the structure can be directly connected from the smoothing capacitors 11 to 16 to the power transistor 17, and the bar conductors that cancel out magnetic flux can be closely attached to each other. can do. FIG. 3 shows a block diagram of the power converter shown in FIGS.

By inserting a current detector 6 for detecting a current flowing through the inverter unit 4 and a circuit breaker 7 between the smoothing capacitors 3, an arrangement structure as shown in FIGS. In the present embodiment in which the current detector 6 is inserted between the smoothing capacitors 3, in addition to the discharge current flowing from the smoothing capacitor 3 which can be detected at the position of the current detector 6 in the conventional device to the inverter unit 4, It is also possible to detect the charging current flowing through the smoothing capacitor 3. However, when the circuit breaker 7 for protecting the main circuit is cut off only by inserting the circuit breaker 7 in the middle of the smoothing capacitor 3, the main circuit voltage detection circuit 8 determines whether the smoothing capacitor 3 is charged with voltage. Not detectable. Therefore, even if the resistor 9 is connected in parallel with the circuit breaker 7 and the circuit breaker 7 is cut off, the voltage of the smoothing capacitor 3 is detected by the main circuit voltage detection path 8 while the smoothing capacitor 3 is being charged. Do.

[0015]

As described above, according to the present invention, in the power converter, the current detector for protecting the main circuit and the circuit breaker are connected between the smoothing capacitors connected in series, so that the smoothing capacitor is connected. And the inverter section can be directly connected by a bar conductor, and the distance between the bar conductor connecting the smoothing capacitor and the power transistor is shortened. Therefore, the inductance of the bar conductors 19 and 20 due to the wiring can be made smaller than that of the conventional device structure, and the surge voltage at the time of switching can be suppressed as much as possible.

Further, an insulator is wound around the bar conductor from each smoothing capacitor to the power transistor, and the bar conductors that cancel out magnetic flux are brought into close contact with each other, so that the wiring structure space is reduced and the inductance is reduced. Surge voltage can be suppressed as much as possible.

[Brief description of the drawings]

FIG. 1 is a structural front view of a main circuit of a power converter according to an embodiment of the present invention.

FIG. 2 is a bottom view of FIG.

FIG. 3 is a block diagram of a main circuit of the power converter according to the embodiment of the present invention;

FIG. 4 is a block diagram of a main circuit of a conventional power converter.

FIG. 5 is a structural front view of a main circuit of a conventional power converter.

FIG. 6 is a bottom view of FIG. 5;

[Explanation of symbols]

1 ... commercial power supply 2 ... converter section 3
... Smoothing capacitor, 4 ... Inverter section, 5 ... Induction motor, 6 ... Current detector, 7 ... Circuit breaker,
8: Main circuit voltage detection circuit, 9: Resistance, 11, 1
2, 13, 14, 15, 16 ... smoothing capacitor, 17 ...
Power transistor, 18: cooling body, 19, 20: bar conductor, 21: current detector, 22: breaker,
23 ... insulator, 24, 25 ... terminals.

Claims (2)

(57) [Scope of request for utility model registration] A converter for converting an AC input to a DC; a smoothing capacitor series circuit connected to the converter for smoothing the DC output from the converter; An inverter unit that is connected to a series circuit via a bar conductor and that includes a power transistor that reversely converts the DC smoothed by the smoothing capacitor series circuit into an AC having a predetermined voltage and frequency. A power converter, wherein the inverter unit, a protection current detector for the converter unit, and a circuit breaker are provided in the middle of a smoothing capacitor forming a capacitor series circuit. 2. The power converter according to claim 1,
An electric power converter characterized in that an insulator is wound around a bar conductor connecting each smoothing capacitor of a smoothing capacitor series circuit and a power transistor of an inverter unit, and the bar conductors in directions in which magnetic fluxes cancel each other are adhered to each other.