JP2005287157A - Noise filter and air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a noise filter which has a large effect of suppressing the noise flowing out by the drive of an inverter, and an air conditioner which is equipped with an inverter device especially for its outdoor unit, having a large effect of suppressing the noise flowing out of an inverter, in simple constitution. <P>SOLUTION: An outdoor unit is equipped with a common mode coil 2 which is provided between an inverter circuit composed of a rectifier 7, an inverter element 10, etc. and a power source 13, line bypass capacitors 4, 5 and 6 which are provided between an earth line connected to an earth 14 and the power line, and a coil 3 for the earth line which is provided in the earth line. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a noise filter for suppressing an outflow noise component in an inverter device. It is particularly suitable for an air conditioner including an inverter device in an outdoor unit.

In a conventional air conditioner with an inverter unit installed in an outdoor unit, a noise filter is configured with a common mode coil and a line bypass capacitor between the power line and ground, and the outflow noise superimposed on the inverter unit The component is suppressed (see, for example, Patent Document 1).
JP 2001-268890 A

  However, as described above, in the method using only the common mode coil as the noise suppression method, it is necessary to increase the diameter of the winding wound around the common mode coil when the power supply current increases. When the common mode coil is viewed in the same core size, the larger the wire diameter, the smaller the number of turns and the smaller the obtained inductance. Therefore, in order to obtain an inductance sufficient to suppress noise, it is necessary to increase the core size and the number of turns, and there are problems such as an increase in coil mounting space and an increase in cost.

  The present invention has been made to solve the above-described problems, and a first object thereof is to obtain a noise filter having a large effect of suppressing noise flowing out by driving an inverter device. The second object is to obtain an air conditioner including an inverter unit in an outdoor unit that has an inexpensive configuration and a large effect of suppressing outflow noise of the inverter unit.

  A noise filter according to the present invention includes a common mode coil provided in a power supply line between a power supply and an inverter circuit, a line bypass capacitor provided between the ground line connected to ground and the power supply line, and a ground line. And a coil for the earth line provided.

  According to the present invention, since another noise coil is provided for the earth line and the noise filter is configured to be provided on the earth line (inserted into the earth line), the coil has a small common mode flowing through the earth line. In order to suppress the noise current, it is possible to make the winding thin by reducing the winding with a small current rating. Therefore, there is an effect that a large inductance can be obtained even with a small size. Also, by providing a coil on the earth line, noise flowing out from the earth line to the power supply is also suppressed, so noise returning to the inverter device via the power supply is also reduced, and a common mode coil provided on the power supply line It is possible to reduce the inductance. Therefore, the common mode coil provided in the power supply line can also reduce the core and the number of turns of the winding by the power supply line, and has an effect of enabling an inexpensive and small configuration as a whole noise filter configuration. .

Embodiment 1 FIG.
FIG. 1 shows a configuration diagram of an outdoor unit of an air conditioner equipped with an inverter device according to Embodiment 1 of the present invention. In this embodiment, an example applied to an outdoor unit of an air conditioner equipped with an inverter device will be described. In FIG. 1, an inverter device composed of a rectifier 7, a reactor 8, a smoothing capacitor 9, and an inverter element 10 is mounted in the outdoor unit 1 of the air conditioner, and the compressor 11 is driven to operate. Further, the common mode coil 2 provided on the power supply line (inserted into the power supply line), line bypass capacitors 4, 5 and 6 provided between the power supply line and the earth line, and an earth line provided on the earth line The coil 3 constitutes a noise filter. This noise filter suppresses common-mode noise components that flow out of the stray capacitances 15, 16, 17, and 18. The outdoor unit 1 of the air conditioner is connected to a power source 13 and a ground 14 via a power source / ground connection terminal block 12. In the present embodiment, the power source 13 is a three-phase AC power source.

  Here, the common mode coil 2 constituting the noise filter has three wires constituting the power supply line wound around the magnetic core in the present embodiment. On the other hand, the coil 3 for the earth line winds one wire constituting the earth line around another magnetic core.

  By driving the rectifier 7, the inverter element 10, and the compressor 11 of the inverter circuit, a noise current (noise component) flows out (generates) to the ground line and flows into the ground 14. Although the noise current is very small, it cannot be ignored. Further, when this noise current flows into the ground 14, noise flows out to the power supply 13. Therefore, the current flowing through the power supply line is also affected, and further noise is generated. Moreover, it is necessary to increase the number of turns of the wire wound around the common mode coil 2 or increase the wire diameter for the countermeasure. Therefore, the ground line coil 3 is provided in the ground line to suppress noise components flowing out to the ground line. Since the noise current flowing out to the earth line is very small, even if the magnetic core of the earth line coil 3 is small, the noise suppressing effect is exhibited. Moreover, since the noise component flowing into the power supply line (outdoor unit 1) is suppressed by providing the earth line coil 3, the common mode coil 2 can be downsized as a result.

  Next, the operation will be described. In the outdoor unit 1 of the air conditioner configured as described above, the rectifier 7, the inverter element 10, and the compressor 11 have stray capacitances 15, 16, and 17, respectively, although not intended. A noise component flows out through the stray capacitances 15, 16, and 17, and a noise current flows through the ground line. This noise current is suppressed by the earth line coil 3 provided on the earth line. Therefore, almost no noise current flows through the ground 14, thereby reducing the noise current flowing out to the power supply 13 and the outdoor unit 1 via the stray capacitance 18. Therefore, the common mode coil 2 necessary for suppressing the noise current can be configured with a core smaller than usual.

  As described above, according to the first embodiment, a minute noise current flowing out to the earth line (earth 14) via the stray capacitance of the inverter device is suppressed by the earth line coil 3 provided on the earth line. As a result, the noise filter can be configured using the ground line coil 3 which is thinned and reduced in size with a small current rating. Therefore, the noise filter can be downsized as a whole without increasing the size of the common mode coil 2. Furthermore, since the noise current flowing out to the ground 14 is reduced by providing the ground line coil 3, the noise returning to the outdoor unit 1 of the air conditioner through the power supply 13 through the stray capacitance 18 is also reduced. . Therefore, since the inductance of the common mode coil 2 provided on the power supply line can be reduced, the core can be reduced and the number of winding turns can be reduced. Is possible.

Embodiment 2. FIG.
In the above-described first embodiment, the noise filter is provided in the outdoor unit of the air conditioner, but the present invention is not limited to this. For example, it can be used for all devices (especially those with a large power supply current) driven using an inverter circuit, such as various pumps, blowers, dust collectors, heaters, and coolers.

It is a block diagram of the outdoor unit of the air conditioner carrying the inverter apparatus in Embodiment 1 of this invention.

Explanation of symbols

1 outdoor unit, 2 common mode coil, 3 ground line coil, 4, 5, 6 line bypass capacitor, 7 rectifier, 8 reactor, 9 smoothing capacitor, 10 inverter element, 11 compressor, 12 power supply / ground connection Terminal block, 13 power supply, 14 ground, 15, 16, 17, 18 stray capacitance.

Claims (3)

A common mode coil provided in a power line between the power source and the inverter circuit;
A line bypass capacitor provided between the ground line connected to ground and the power supply line;
A noise filter comprising a ground line coil provided on the ground line.   The noise filter according to claim 1, wherein the coil for the earth line is a small coil having a large inductance. An air conditioner comprising the noise filter according to claim 1 or 2 in an outdoor unit.

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