JP2008104307A - Noise suppressor for semiconductor power conversion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain noise reduction with a ferrite core and reduction in size and cost. <P>SOLUTION: In a semiconductor power conversion device including filter circuits 2, 3 for removing high frequency provided to the input part of an AC power source 1 and power conversion unit for converting AC to DC with a converter 4 using semiconductor elements as main circuit switching elements to supply the DC to a load, ground wires 2E, 4E, 5E, 6E for a CR filter, a converter, an inverter and an inductor motor are pulled around a ground bus line 10 for wiring, and are wound between the ferrite cores 11, 12 for the reduction in noises leaking from each section by the required number of times to be connected to the bus line. Respective ground wires are wound around the ferrite core so that their polarities of the main current in the ground current flowing into the ground wires are mutually reversed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a noise reduction device that suppresses noise leakage from a semiconductor power conversion device to an external device using a ferrite core.

  As a semiconductor power conversion apparatus according to the present invention, a main configuration of an inverter apparatus that drives an induction motor at a variable speed is shown in FIG. The input section to which an AC power source 1 such as a commercial power source is connected is provided with a high frequency removing filter circuit comprising a CR filter 2 for suppressing harmonics and an AC reactor 3, and the AC − AC power is taken into the converter 4 as a DC power converter. The inverter 5 as a DC-AC power conversion unit uses the converter 4 as a DC power supply, controls the voltage and frequency, and further obtains a PWM-controlled three-phase output, and outputs this AC current to the induction motor 6 serving as a load as an output transformer. The induction motor 6 is driven at a variable speed.

  The converter 4 and the inverter 5 are provided with power semiconductor elements such as diodes, IGBTs, GTOs, and transistors as main switch elements, and obtain a desired power conversion operation by switching them. A pulsed current flows, and this current is induced as noise in peripheral computers and other devices connected to an AC power supply, causing malfunction of these external devices.

  As a noise reduction method for suppressing noise leakage from the inverter device to the external device, a ferrite core 7 and a ferrite core 8 are attached to a three-phase cable of an AC input unit and an inverter output unit, and further, an induction motor ground wire is connected. A ferrite core 9 is attached to the included four-phase cable, and noise is prevented from leaking to the outside by high frequency electromagnetic induction generated between the ferrite cores 7 to 9 and the cable.

The ferrite core is formed into a donut-shaped integral structure or an assembly structure of a plurality of square core materials, and a three-phase cable or a four-phase cable is wound around this several turns. Furthermore, a plurality of ferrite cores are integrated and a cable is wound around them (see, for example, Patent Document 1).
JP 2000-340375 A

  In the attached structure of the ferrite core as described above, since the three-phase cable requires a large current capacity, the wire diameter and the insulation coating become large, and an expected number of turns is obtained between the ferrite core and the cable. Increases the size of the ferrite core and the required number. Further, since the ferrite core generates heat due to the high frequency current, its cooling structure is required.

  Under these circumstances, the conventional noise reduction device has a problem of increasing the size and cost of the device including the ferrite core and the cable.

  An object of the present invention is to provide a noise reduction device for a semiconductor power conversion device that has solved the above-described problems.

  In order to solve the above-mentioned problems, the present invention is configured such that the ground wire of each part constituting the semiconductor power conversion device and the ground wire of the load are routed to the ground bus and wired so that the ground as the semiconductor power conversion device is integrated with the ground bus. These ground wires are wound around the ferrite core by the required number of turns and connected to the ground bus, and have the following configuration.

(1) A filter circuit for removing high frequency is provided at an input unit that takes in AC power from an AC power source, and a power conversion unit that converts the AC power into AC or DC and supplies it to a load using a semiconductor element as a main circuit switch element is provided. In the semiconductor power converter
The input unit, the power conversion unit and the ground wire of the load are routed to the ground bus of the semiconductor power conversion device, and each ground wire is necessary between the ferrite core for reducing noise leaking from the semiconductor power conversion device. The configuration is characterized in that it is wound by the number of turns and connected to the ground bus.

  (2) Each of the ground wires is characterized in that it is wound around the ferrite core so that the polarities of the main currents out of the ground currents flowing through them are opposite to each other.

  As described above, according to the present invention, the ground wire as the semiconductor power converter is unified by the ground bus by routing the ground wire of each part constituting the semiconductor power converter and the ground wire of the load to the ground bus. Since these ground wires are wound around the ferrite core by the required number of turns and connected to the ground bus, the following effects are obtained.

  (1) The ferrite core only needs to have a configuration in which only a very thin ground wire is wound compared to the power cable, so that it is possible to reduce the size, reduce the cost, and reduce the required quantity. And cost reduction.

  (2) Since the ground current is very small compared to the output current of the power converter, the high-frequency noise current flowing in the ferrite core is also reduced, and the heat generated in the ferrite core can be reduced to a small amount, and the cooling No structure is required. In particular, a remarkable effect can be obtained by winding the ferrite core so that the polarities of the main currents out of the ground currents flowing through the respective ground wires are opposite to each other.

  FIG. 1 shows an embodiment of the present invention, which is applied to an inverter device. 2 differs from FIG. 2 in that the ground wire of each part constituting the inverter device and the ground wire of the load are routed to the ground bus, and the ground as the inverter device is unified by the ground bus. Is wound around a ferrite core and connected to a ground bus.

  In FIG. 1, the ground wire 2 </ b> E of the filter circuit 2, the ground wire 4 </ b> E of the converter 4, the ground wire 5 </ b> E of the inverter 5 and the ground wire 6 </ b> E of the induction motor 6 are respectively routed to the position of the ground bus 10. Ground.

  In ferrite core 11, both ground wire 2E of filter circuit 2 and ground wire 4E of converter 4 are wound by the required number of turns, and both ground wires 2E and 4E are connected to ground bus 10, respectively. Here, the winding direction of both ground wires around the ferrite core 11 is wound so that the polarities of the main currents out of the ground currents flowing through the ground wire 2E and the ground wire 4E are opposite to each other. The polarities of these main currents are indicated by arrows in the figure.

  In ferrite core 12, both ground wire 5E of inverter 5 and ground wire 6E of induction motor 6 are wound by the required number of turns, and both ground wires 5E and 6E are connected to ground bus 10, respectively. In this case as well, the winding direction of both ground wires around the ferrite core 12 is wound so that the polarities of the main currents out of the ground currents flowing through the ground wire 5E and the ground wire 6E are opposite to each other. The polarities of these main currents are indicated by arrows in the figure.

  According to the noise reduction device having the above configuration, each of the ground wires 2E, 4E, 5E, and 6E has a single-wire configuration and a small earth current capacity. Compared with very thin lines. Thereby, in order to wind the necessary number of turns around the ferrite cores 11 and 12, it is possible to use a ferrite core that is significantly reduced in size as compared with the conventional method.

  Further, since the ground wires 2E and 4E are wound around one ferrite core 11 and their main ground currents have opposite polarities, the amount of magnetic flux generated in the ferrite core 11 is canceled out by both ground currents. The heat generation of the ferrite core 11 can be greatly reduced. Similarly, the main ground currents of the ground wires 5E and 6E wound around the ferrite core 12 have opposite polarities, and the heat generation of the ferrite core 12 can be greatly reduced.

  Although the embodiment shows a case where the present invention is applied to an inverter device, the present invention uses a semiconductor element such as a power chopper or a cycloconverter as a main switch element and is applied to a semiconductor power conversion device having a large current capacity. An effect can be obtained.

  In the embodiment, the converter ground wire and the CR filter ground wire are wound around one ferrite core, and the inverter ground wire and the induction motor ground wire are wound around one ferrite core. The design is appropriately changed according to the configuration of the semiconductor power conversion device, such as a configuration in which a plurality of ground wires are wound around one ferrite core, and a configuration in which a plurality of ground wires are wound around three or more ferrite cores.

The principal part block diagram of the inverter apparatus which shows embodiment of this invention. The principal part block diagram of the conventional inverter apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 CR filter 3 AC reactor 4 Converter 5 Inverter 6 Induction motor 7-9 Ferrite core 10 Ground bus 11, 12 Ferrite core

Claims (2)

Semiconductor power provided with a high frequency elimination filter circuit at the input section for taking in AC power from an AC power supply, and with a power conversion section for converting the AC power into AC or DC power and supplying it to a load using a semiconductor element as a main circuit switch element In the conversion device,
The input unit, the power conversion unit, and the load ground wire are routed to the ground bus of the semiconductor power conversion device, and each ground wire is necessary between the ferrite core for reducing noise leaking from the semiconductor power conversion device. A noise reduction device for a semiconductor power conversion device, characterized in that it is wound by the number of turns and connected to the ground bus.   2. The noise of the semiconductor power converter according to claim 1, wherein each of the ground wires is wound around the ferrite core such that polarities of main currents out of ground currents flowing through the ground wires are opposite to each other. Reduction device.

Images