JP2012110092A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion device by which a high-frequency noise superposed on an output cable is less likely to be induced to an input cable while keeping the size of the device small without increasing the cost of the device.SOLUTION: A power conversion device has an output terminal for extracting an AC voltage converted by an inverter converting a DC voltage outputted from a converter, which converts an AC voltage of a commercial power supply into the DC voltage and outputting the DC voltage, into the desired AC voltage. The power conversion device has a ground conductor provided in the vicinity of the output terminal and connected to a ground line of the inverter. An output cable connected to the output terminal is arranged at a section where electrical coupling with the ground conductor becomes large.

Description

  The present invention relates to a power converter, and more particularly, to a technique for suppressing noise generated inside the power converter from flowing out to a commercial AC power source.

  FIG. 5 is a diagram showing a schematic configuration of a general power conversion device 1 that obtains a desired AC voltage / AC current from a three-phase commercial AC power source 2. The power conversion device 1 is connected to a noise filter circuit 4 provided to prevent noise generated in the power conversion device 1 from being transmitted to the commercial AC power supply 2 side, and an output side of the noise filter circuit 4, A converter 5 that converts an AC voltage input from the commercial AC power source 2 into a DC voltage, a smoothing capacitor 6 that smoothes a pulsation waveform output from the converter 5, and an output side of the smoothing capacitor 6 to switch a semiconductor element Thus, an inverter 7 that outputs an AC voltage / AC current required by the load 3 is provided.

  FIG. 6 is a schematic diagram showing a conventional power conversion device 1. A three-phase commercial AC power supply 2 (not shown in FIG. 6) to an input cable 8 (a cable connecting the commercial AC power supply 2 and the power converter 1 or a LISN (pseudo power supply network) and the power converter 1 3 phase AC power is supplied to the noise filter circuit 4 (not shown in FIG. 6) via the input terminal block 10 and the input bus bar 12 in order.

  The input cable 8 connected to the three-phase commercial AC power supply 2 is drawn into the power converter 1 from the external wiring inlet of the casing 17 of the power converter 1. Within the power converter 1, the wires of the three phases of the input cable 8 (here, R phase, S phase, and T phase; the same applies hereinafter) are connected to the R phase, S phase, and T phase of the input terminal block 10. The ground wire of the input cable 8 is connected to each terminal, and the ground wire of the input cable 8 is connected to the input ground terminal 14 configured by, for example, an L-shaped conductive member 16 a provided on the cooling fin 18 of the converter 5 and / or the inverter 7.

  The three-phase AC power output from the inverter 7 passes through the output bus bar 13, the output terminal block 11, and the output cable 9 (cable connecting the power converter 1 and the load 3) in order, and loads (in FIG. 6). (Not shown). The output cable 9 connected to the load is drawn into the power conversion device 1 from the external wiring inlet of the housing 17 of the power conversion device 1. In the power conversion device 1, the U-phase, V-phase, and W-phase electric wires of the output cable 9 are connected to the U-phase, V-phase, and W-phase terminals of the output terminal block 11, respectively. The wire and the shield wire are connected to an output ground terminal 15 configured by, for example, an L-shaped conductive member 16b.

  In such a power conversion device, for example, when each phase of the inverter 7 has a configuration having upper and lower arms of semiconductor elements, high-frequency voltage fluctuations occur at the midpoints of the upper and lower arms due to switching of these semiconductor elements. To do. This passes through the output cable 9 and becomes a high-frequency leakage current that charges and discharges the stray capacitance between the winding of the load 3 such as the motor and the frame, and is transmitted through the ground wire and the shield wire of the output cable 9. Reach body ground.

  In order to prevent the high-frequency leakage current flowing through the output cable 9 from flowing into the input cable 8, the distance (distance) between the cables should be as large as possible. However, the arrangement of the input bus bar 12 and the output bus bar 13 is roughly determined by the size of the power conversion device 1. That is, how far the distance between the input terminal block 10 and the output terminal block 11 and the distance between the input cable 8 and the output cable 9 connected to the input terminal block 10 and the output terminal block 11, respectively, in the vicinity of the connection point are separated. It can be said that this is determined by the design of the manufacturer of the power converter 1.

  On the other hand, when a person who has no knowledge of noise uses the power conversion device 1, there is a concern that the input cable 8 and the output cable 9 may be bundled in a binding band so as to keep the cables in order. At this time, the input cable 8 and the output cable 9 in the place bundled with the binding band are closer to each other than the distance between the terminal blocks 10 and 11 and the input / output cable 8 and the input cable 8 and the output cable 9 near the connection place. Resulting in. Since the capacitive coupling / inductive coupling between the input / output cables 8 and 9 at the location combined by the binding band is large, the high frequency noise flowing through the output cable 9 is induced to the input cable 8 side at this location. The high-frequency noise current leaked from the noise filter circuit 4 to the input cable portion on the commercial AC power supply 2 side returns to the power converter 1 around the commercial AC power supply 2 side, so that it deviates from the noise standard or is the same Cause malfunction of another device connected to the commercial AC power source.

  Therefore, a technique is disclosed in which a noise filter such as a common mode choke is installed on the output side of the power converter to prevent high frequency noise from being superimposed on the output cable of the power converter (see, for example, Patent Document 1). ). In Patent Document 1, a plurality of noise filters are provided and the plurality of noise filters are connected in parallel to each other. Even in the case of a power converter for high power, the core causes magnetic saturation or the cable diameter increases. There is nothing to do. Further, according to Patent Document 1, since high-frequency noise can be prevented from flowing out to the output cable, high-frequency noise induced in the input cable is reduced even when the capacitive coupling / dielectric coupling between the input and output cables is large. Is possible.

JP 2001-231268 A

  However, the method disclosed in Patent Document 1 described above has a configuration in which a plurality of noise filters are connected in parallel to each other in order to prevent the core from causing magnetic saturation or an increase in the cable diameter in the power converter for high power. ing. For this reason, the installation space of a plurality of noise filters and connection wiring with the plurality of noise filters is increased, so that there is a problem that the power converter cannot be reduced in size and the cost of the power converter increases.

  Next, electrical coupling, which is a factor that makes noise worse, will be described. It is well known that in a printed board that performs high-speed transmission, the crosstalk due to capacitive coupling and inductive coupling cannot be ignored as the distance between wirings decreases and the conduction speed increases. Although there is a difference between a high-speed printed board and a power converter, the capacitive coupling and inductive coupling that cause this crosstalk are collectively referred to as electrical coupling. Here, crosstalk is a phenomenon that deteriorates the transmission signal due to the effects of both capacitive coupling and inductive coupling (electrical coupling), but grasps the effects of capacitive coupling and inductive coupling completely separately. That is difficult in principle. For example, as the inter-wiring distance decreases, the influence of crosstalk increases and signal transmission becomes difficult. At this time, both electrostatic coupling and inductive coupling increase. Conversely, as the inter-wiring distance increases, the influence of crosstalk decreases and signal transmission becomes easier, but both electrostatic coupling and inductive coupling decrease. In other words, it is rather difficult to control only one of the effects when taking measures to reduce the influence of capacitive coupling and inductive coupling, and even measures intended for one can be applied to both capacitive coupling and inductive coupling. In general, a countermeasure effect can be obtained.

  Next, the cause of noise deterioration will be considered by applying the principle of crosstalk to a power converter. It is well known that a portion where a large current flows and a portion where the noise is small exist in the power converter. At this time, in a power conversion device having a configuration in which a portion where a large current flows and a portion where the noise is small are close to each other, the current in the portion where the noise is large is induced to the portion where the noise is small due to electrical coupling. And there also existed a problem that the induced high frequency leakage current reached LISN and noise was greatly measured. In order to prevent this type of problem, it is important to reduce the electrical coupling between the noisy output side and the noisy input side, and it is particularly effective to increase the physical distance. However, it cannot be applied to a power conversion device in which the distance between the input / output terminal blocks is determined in advance.

  Therefore, as another method for reducing the electrical coupling between the input side and the output side, it is known to install a ground potential flat plate directly under the input cable and / or the output cable. This is because the magnitude of capacitive coupling between objects is determined by the number of electric lines of force between objects (per unit area). Specifically, when an object with ground potential approaches the input line or output line, part of the lines of electric force that have been directed between the input line and output line until now extend from the input line or output line to the object with ground potential. It becomes like this. Therefore, the number of lines of electric force between the input line and the output line is reduced, and the capacitance is reduced. That is, the capacitive coupling between the input line and the output line is reduced, and the ratio of the current with a high noise level flowing to the output side flowing out to the input line is reduced, so that the measured noise level is lowered. If this concept is applied to a power conversion device, noise can be reduced because an inductive coupling is similarly reduced by installing an object having a ground potential near the input / output line. When this principle is replaced with a high-speed printed circuit board, the effect of crosstalk is reduced by using a microstrip line or a strip line in which the adjacent layer of the signal line is a solid pattern rather than transmitting a signal alone. The effect is considered to be similar.

  Or, when the ground plate is installed directly under both the input cable and the output cable, it is most effective, but even if only one of them is installed, a certain degree of effect may be obtained. Furthermore, since the coupling between the grounds becomes smaller when the ground is made of one flat conductor, the effect between the ground and the input side is reduced, and the effect is further enhanced.

  The power converter of the present invention has been made on the basis of such knowledge, and an object thereof is to solve the above-mentioned problems of the prior art. Specifically, an object of the present invention is to provide a power conversion device in which high-frequency noise superimposed on an output cable is not easily induced in an input cable without increasing the cost of the device while keeping the device small. .

  In order to achieve the above-described object, the power conversion device of the present invention includes an input terminal (for example, configured by a terminal block) to which commercial power is input, and an AC voltage of the commercial power supplied to the input terminal as a DC voltage. A converter that converts and outputs to the inverter, an inverter that converts the DC voltage output from the converter into a desired AC voltage, and an output terminal that extracts the AC voltage converted by the inverter (for example, a terminal block) A power conversion device comprising: a ground conductor provided in the vicinity of the output terminal and connected to a ground line; and an output cable connected to the output terminal is electrically coupled to the ground conductor. It is characterized in that it is arranged at a part where becomes large.

  In the above-described power conversion device, the output cable connected to the output terminal is arranged at a location where the electrical coupling with the ground conductor is large, so that the electrical coupling between the ground conductor and the output cable (capacitive coupling / inductive coupling) As the value increases, the electrical coupling between the input cable and the output cable decreases. Therefore, high frequency noise induced in the input cable is reduced.

  Alternatively, the power conversion device of the present invention includes an input terminal to which commercial power is input, a converter that converts an AC voltage of the commercial power supplied to the input terminal into a DC voltage, and a DC output from the converter. A power conversion device including an inverter that converts a voltage into a desired AC voltage and an output terminal that extracts an AC voltage converted by the inverter, the power conversion device being provided near the input terminal and connected to a ground line An input cable having a ground conductor and connected to the input terminal is arranged at a portion where electrical coupling with the ground conductor is increased.

  In the power conversion device described above, the input cable connected to the input terminal is arranged at a location where the electrical coupling with the grounding conductor is increased, so that the electrical coupling between the grounding conductor and the input cable is increased, so that the input The electrical coupling between the cable and the output cable is reduced. Therefore, high frequency noise induced in the input cable is reduced.

  The power converter according to the present invention includes an input terminal to which a commercial power supply is input, a converter that converts an AC voltage of the commercial power supplied to the input terminal into a DC voltage, and a DC output from the converter. A power conversion device including an inverter that converts a voltage into a desired AC voltage and an output terminal that extracts an AC voltage converted by the inverter, the power conversion device being provided near the input terminal and connected to a ground line An input side ground conductor and an output side ground conductor provided in the vicinity of the output terminal and connected to a ground line, and the input cable is located at a portion where electrical coupling with the input side ground conductor is increased. The output cable is arranged at a portion where electrical coupling with the output-side ground conductor is increased.

  In the power conversion device described above, the input cable connected to the input terminal and the output cable connected to the output terminal are arranged in a portion where electrical coupling with the ground conductor is increased. The electrical coupling between and becomes stronger. Therefore, the electrical coupling between the input cable and the output cable is reduced, and high frequency noise induced from the output cable to the input cable is reduced.

Alternatively, the power conversion device of the present invention includes an input terminal to which commercial power is input, a converter that converts an AC voltage of the commercial power supplied to the input terminal into a DC voltage, and a DC output from the converter. A power conversion device including an inverter that converts a voltage to a desired AC voltage and an output terminal that extracts an AC voltage converted by the inverter,
Proximate to the input terminal and the output terminal, and having a ground conductor connected to a ground line, the input cable connected to the input terminal and the output cable connected to the output terminal are respectively connected to the ground conductor. It is characterized by being arranged at a site where electrical coupling is increased.

  In the power conversion device described above, the input cable connected to the input terminal and the output cable connected to the output terminal are arranged in a portion where electrical coupling with the ground conductor is increased. The electrical coupling between and becomes stronger. Therefore, the electrical coupling between the input cable and the output cable is reduced, and high frequency noise induced from the output cable to the input cable is reduced.

  As described above, according to the present invention, it is possible to suppress induction of high-frequency noise from the output cable to the input cable without installing a noise filter at the output of the power converter.

It is the schematic which shows the power converter device which concerns on 1st embodiment of this invention. It is the schematic which shows the power converter device which concerns on 2nd embodiment of this invention. It is the schematic which shows the power converter device which concerns on 3rd embodiment of this invention. It is the schematic which shows the power converter device which concerns on 4th embodiment of this invention. It is a schematic block diagram of the power converter device which acquires electric power from a three-phase commercial alternating current power supply. It is the schematic which shows the conventional power converter device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, FIGS. 1-4 is for demonstrating the power converter device which concerns on one Embodiment of this invention, and this invention is not limited by these figures.
[First embodiment]
FIG. 1 is a schematic diagram showing a power conversion apparatus 1 according to the first embodiment of the present invention. The same functional members as those of the conventional power conversion apparatus of FIG. To do.

  Now, in the power conversion device 1 shown in FIG. 1, in the region from the output terminal block 11 to the external wiring lead-in port of the housing 17, the output provided on the cooling fin 18 at the lower position where the output cable 9 is installed. An output-side conductor (ground conductor) 19b having the same potential as the ground line grounded to the housing 17 via the ground terminal 15 is provided. In this embodiment, the output side ground conductor 19b has a plate shape.

  FIG. 1B is a schematic front view of the power converter 1 (a cross-sectional view taken along the line AA in FIG. 1A). As shown in FIG. 1B, the output cable 9 and the insulator 20, and the insulator 20 and the output-side ground conductor 19b are arranged so as to contact each other. Normally, the power converter is manufactured so that there is no exposed metal part other than the connection terminal with the cable, but in order to take insulation between the output cable 9 and the output side ground conductor 19b which is the exposed metal part, The insulator 20 is sandwiched between the output cable 9 and the output-side ground conductor 19b.

By adopting such a configuration, the capacitive coupling between the output cable 9 and the output side ground conductor 19b is further strengthened with respect to the capacitive coupling between the input cable 8 and the output cable 9. Propagating high frequency noise is not induced in the input cable 8. Therefore, according to the power conversion device according to the first embodiment of the present invention, high-frequency noise propagating through the output cable 9 is induced to the input cable 8 without installing a noise filter on the output side of the power conversion device 1. Can be suppressed.
[Second Embodiment]
FIG. 2 is a schematic diagram showing a power conversion device 1 according to the second embodiment of the present invention. The same functional members as those of the power conversion device 1 according to the first embodiment of the present invention described above are denoted by the same reference numerals and description thereof is omitted.

  The second embodiment differs from the first embodiment described above in that an input-side ground conductor 19a grounded to the housing 17 is provided near the lower portion of the position where the input cable 8 is installed. .

  According to the second embodiment of the present invention configured as described above, the electrostatic coupling between the input cable 8 and the input-side ground conductor 19a becomes strong, and high-frequency noise propagating through the output cable 9 is induced in the input cable 8. Not.

As described above, the power conversion device according to the second embodiment of the present invention can suppress high-frequency noise induced in the input cable.
[Third embodiment]
FIG. 3 is a schematic diagram showing a power converter 1 according to the third embodiment of the present invention. The same functional members as those of the power conversion device 1 according to the second embodiment of the present invention described above are denoted by the same reference numerals and description thereof is omitted.

  The third embodiment differs from the second embodiment described above in that an input-side ground conductor 19a grounded to the housing 17 near the lower portion of the input cable 8 and the output cable 9 as shown in FIG. The output side ground conductor 19b grounded to the housing 17 is separated into separate conductors in the vicinity of the lower portion thereof. The input side ground conductor 19a is connected to the input ground terminal 14 and the output side ground conductor 19b is connected to the output ground terminal 15.

  In the second embodiment, high-frequency noise induced from the output cable 9 to the input-side ground conductor 19a may flow to the ground wire of the input cable 8 via the input-side ground conductor 19a. By separating the ground conductor and the ground terminal on the input side and the output side as in the embodiment, high-frequency noise does not flow out to the input cable side directly via the ground conductor.

Therefore, the power conversion device according to the third embodiment of the present invention is preferable because it can further suppress high-frequency noise induced in the input cable.
[Fourth embodiment]
FIG. 4 is a schematic diagram showing a power converter 1 according to the third embodiment of the present invention. The same functional members as those of the power conversion device 1 according to the first to third embodiments of the present invention described above are denoted by the same reference numerals, and description thereof is omitted.

  The fourth embodiment is different from the above-described embodiment in that ground conductors 19 are provided close to the lower portion of the input cable 8 and the lower portion of the output cable 9 as shown in FIG.

  In this embodiment, the capacitive coupling between the input cable 8 and the ground conductor 19 and between the output cable 9 and the ground conductor 19 is larger than the capacitive coupling between the input cable 8 and the output cable 9. Become. That is, the electric power converter according to the fourth embodiment of the invention suppresses the electric lines of force between the output cable 9 and the input cable 8, and suppresses high-frequency noise induced in the input cable. It becomes possible.

  In each of the embodiments described above, the conductors 19a, 19b, 19 are plate-shaped, but the present invention is not limited to this. For example, a configuration may be adopted in which a cylindrical portion is prepared and an output cable is passed therethrough. Moreover, although the insulator 20 is laid between the cable and the conductor, the insulator 20 is not indispensable (that is, it may not be present). This insulator 20 merely prevents the core wire from accidentally contacting the conductor and short-circuiting when the core wire appears near the terminal block due to some damage to the cable insulation film.

  As described above, according to the present invention, even if no noise filter is installed at the output of the power converter, there is a practically great effect that high-frequency noise can be suppressed from being guided from the output cable to the input cable. .

DESCRIPTION OF SYMBOLS 1 Power converter 2 Commercial AC power supply 4 Noise filter circuit 5 Converter 7 Inverter 8 Input cable 9 Output cable 10 Input terminal block 11 Output terminal block 14 Input ground terminal 15 Output ground terminal 17 Case 18 Cooling fin 19 Ground conductor 19a Input side Ground conductor 19b Output side ground conductor 20 Insulator

Claims (4)

An input terminal to which commercial power is input;
A converter that converts the AC voltage of the commercial power supply given to the input terminal into a DC voltage and outputs it;
An inverter that converts the DC voltage output from the converter into a desired AC voltage;
An electric power conversion device comprising an output terminal for extracting an AC voltage converted by the inverter,
A ground conductor provided near the output terminal and connected to a ground line;
The power conversion apparatus according to claim 1, wherein an output cable connected to the output terminal is disposed at a portion where electrical coupling with the ground conductor is increased. An input terminal to which commercial power is input;
A converter that converts the AC voltage of the commercial power supply given to the input terminal into a DC voltage and outputs it;
An inverter that converts the DC voltage output from the converter into a desired AC voltage;
An electric power conversion device comprising an output terminal for extracting an AC voltage converted by the inverter,
A ground conductor provided near the input terminal and connected to a ground line;
The power converter according to claim 1, wherein an input cable connected to the input terminal is disposed in a portion where electrical coupling with the ground conductor is increased. An input terminal to which commercial power is input;
A converter that converts the AC voltage of the commercial power supply given to the input terminal into a DC voltage and outputs it;
An inverter that converts the DC voltage output from the converter into a desired AC voltage;
An electric power conversion device comprising an output terminal for extracting an AC voltage converted by the inverter,
An input-side ground conductor provided near the input terminal and connected to a ground line;
An output side ground conductor provided near the input terminal and connected to a ground line;
The input cable is disposed at a portion where electrical coupling with the input side ground conductor is increased, and the output cable is disposed at a portion where electrical coupling with the output side ground conductor is increased. A power converter. An input terminal to which commercial power is input;
A converter that converts the AC voltage of the commercial power supply given to the input terminal into a DC voltage and outputs it;
An inverter that converts the DC voltage output from the converter into a desired AC voltage;
An electric power conversion device comprising an output terminal for extracting an AC voltage converted by the inverter,
A ground conductor connected to a ground line in proximity to the input terminal and the output terminal;
The power converter according to claim 1, wherein the input cable connected to the input terminal and the output cable connected to the output terminal are respectively arranged at portions where electrical coupling with the ground conductor is increased.