JP2016103923A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve noise suppression effects in a filter part including a clamper which is connected from a connection point of two capacitors to a frame ground, the two capacitors being connected in series between a first line and a second line which connect a common-mode choke coil and a rectifier.SOLUTION: A filter part 3 includes a filter circuit 3j and a filter circuit 3k which are connected between an output terminal 3m and an output terminal 3n. The filter circuit 3j includes a capacitor 3b and a capacitor 3c which are connected in series between the output terminal 3m and the output terminal 3n, and a clamper 3e which is connected between a connection point of the capacitors and the frame ground. The filter circuit 3k includes a capacitor 3f and a capacitor 3g which are connected in series between the output terminal 3m and the output terminal 3n, and a connection point of the capacitor and the frame ground are connected.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an air conditioner, and more particularly to a noise filter connected to an AC power supply line.

Conventionally, an air conditioner has a configuration shown in the block diagram of FIG.
The air conditioner 50 in FIG. 3 includes an indoor unit 20 and an outdoor unit 40 that is communicatively connected to the indoor unit 20.
The outdoor unit 40 includes an input end 3h and an input end 3i to which an AC power supply (not shown) is connected, a filter unit 30 having an output end 3m and an output end 3n corresponding to these input ends, and each output of the filter unit 30 The rectifier 4 whose end is connected to the input side, the boost chopper circuit 5 connected to the output side of the rectifier 4, the inverter 6 connected to the output side of the boost chopper circuit 5, and the output of the inverter 6 are connected. The compressor 7 and the outdoor unit controller 8 that controls the outdoor unit 40 in accordance with a communication instruction output from the indoor unit 20 and outputs a drive signal to the boost chopper circuit 5 and the inverter 6 are provided. The compressor 7 to which a high voltage is applied to the internal motor is connected to a frame ground for ensuring safety.

  The filter unit 30 is connected in series between the capacitor 3a connected between the input terminal 3h and the input terminal 3i, between the input terminal 3h and the output terminal 3m, and between the input terminal 3i and the output terminal 3n. Common mode choke coil 3d, capacitor 3o connected between output terminal 3m and output terminal 3n, capacitor 3b and capacitor 3c connected in series between output terminal 3m and output terminal 3n, and capacitor 3b And a capacitor 3c having one end connected to the connection point of the capacitor 3c and the other end connected to the frame ground, and a capacitor 30a connected in parallel to the clamper 3e. A line connecting the input terminal 3h and the output terminal 3m is called a first line, and a line connecting the input terminal 3i and the output terminal 3n is called a second line.

  As described above, the outdoor unit 40 includes the step-up chopper circuit 5 and the inverter 6, which turn on / off a large current in accordance with a pulse signal input as a drive signal, so that a large noise voltage is generated. The generated noise voltage is a common mode noise voltage between the signal line or power supply line (including the first line and the second line) of the air conditioner 50 and the frame ground.

  Since the connection point between the capacitor 3b and the capacitor 3c is connected to the frame ground via the clamper 3e and the capacitor 30a, these components are applied between the first line and the second line and the frame ground. Noise can be reduced by short-circuiting the common mode noise voltage.

  Increasing the capacitances of the capacitors 3b and 3c improves the noise suppression effect at a relatively low frequency, while an alternating current flows from the first line and the second line to the frame ground, resulting in an increase in leakage current. . For this reason, the leakage current is suppressed by flowing the current only when the voltage at the connection point between the capacitor 3b and the capacitor 3c becomes equal to or higher than the voltage defined by the clamper 3e. For noise with a high frequency, the capacitor 30a bypasses the clamper 3e so that the noise suppression effect does not deteriorate. (For example, refer to Patent Document 1).

  However, since the common mode noise flowing in the first line and the second line passes through one stage of the capacitor 3b or the capacitor 3c and then passes through another stage of the capacitor 30a, the impedance in this path becomes high, and the capacitor 1 There is a problem that the noise suppression effect is reduced as compared with the case of passing through the step.

Japanese Patent No. 3825678 (page 4-5, FIG. 1)

  The present invention solves the above-described problems and connects between the connection point of two capacitors connected in series between the first line and the second line connecting the common mode choke coil and the rectifier to the frame ground. An object of the present invention is to improve a noise suppression effect in a filter unit including a clamper.

In order to solve the above-described problems, the present invention includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal to which an AC power source is connected. A filter unit, a rectifier connected to the first output end and the second output end of the filter unit, an inverter driven using a DC power source output from the rectifier, and a drive driven by the inverter An air conditioner including a compressor having a casing connected to a frame ground,
The filter unit is
A common mode choke coil connected in series between the first input end and the first output end, and between the second input end and the second output end;
A first filter circuit and a second filter circuit connected between the first output terminal and the second output terminal, or between the first input terminal and the second input terminal;
The first filter circuit includes a first capacitor and a second capacitor connected in series between the first output terminal and the second output terminal, a connection point between the first capacitor and the second capacitor, and the frame. It consists of a clamper connected between the ground and
The second filter circuit includes a third capacitor and a fourth capacitor that are connected in series between the first output terminal and the second output terminal, and that have a smaller capacity than the first capacitor and the second capacitor. A connection point between the third capacitor and the fourth capacitor is connected to the frame ground.

By using the above means, according to the air conditioner of the present invention,
The invention according to claim 1 eliminates the capacitor connected in parallel to the clamper provided in the filter unit of the conventional air conditioner, and instead is connected in series between the first output terminal and the second output terminal. Since the second filter circuit having the third capacitor and the fourth capacitor having a smaller capacity than the first capacitor and the second capacitor is provided independently, the common mode noise is reduced as compared with the filter part of the conventional air conditioner. Can be made.

It is a block diagram which shows the Example of the air conditioner by this invention. It is a graph which shows the noise terminal voltage measurement result in the air conditioner by this invention. It is a block diagram which shows the conventional air conditioner. It is a graph which shows the noise terminal voltage measurement result in the conventional air conditioner.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail as examples based on the attached drawings. Although the air conditioner 1 shown in FIG. 1 includes a heat exchanger, a blower fan motor, and a solenoid valve, these are not directly related to the present application, and illustration and description thereof are omitted.

The air conditioner 1 shown in FIG. 1 includes an indoor unit 20 and an outdoor unit 10 that is communicatively connected to the indoor unit 20.
The outdoor unit 10 includes an input terminal 3h (first input terminal) and an input terminal 3i (second input terminal), an output terminal 3m (first output terminal), and an output terminal 3n (second output) to which an AC power supply (not shown) is connected. Output section), a rectifier 4 in which each output terminal of the filter section 3 is connected to the input side, a boost chopper circuit 5 connected to the output side of the rectifier 4, and an output of the boost chopper circuit 5 The inverter 6 is connected to the side, the compressor 7 is connected to the output of the inverter 6 and the casing is connected to the frame ground, and the outdoor unit 10 is controlled and boosted according to the communication instruction output from the indoor unit 20 An outdoor unit control unit 8 that outputs drive signals to the chopper circuit 5 and the inverter 6 is provided.

  The filter unit 3 is connected in series between the capacitor 3a connected between the input terminal 3h and the input terminal 3i, between the input terminal 3h and the output terminal 3m, and between the input terminal 3i and the output terminal 3n. A common mode choke coil 3d, a capacitor 3o, a filter circuit 3j (first filter circuit), and a filter circuit 3k (second filter circuit) connected between the output terminal 3m and the output terminal 3n, respectively, are provided.

The filter circuit 3j has one end connected to a connection point between the capacitor 3b (first capacitor) and the capacitor 3c (second capacitor) connected in series between the output end 3m and the output end 3n, and the capacitor 3b and the capacitor 3c. The other end of the clamper 3e is connected to the frame ground.
The filter circuit 3k includes a capacitor 3f (third capacitor) and a capacitor 3g (fourth capacitor) connected in series between the output terminal 3m and the output terminal 3n. The connection point between the capacitor 3f and the capacitor 3g is connected to the frame ground.

  A line connecting the input terminal 3h and the output terminal 3m is called a first line, and a line connecting the input terminal 3i and the output terminal 3n is called a second line.

  Capacitor 3a and capacitor 3o suppress normal mode noise that flows out of outdoor unit 10 between the lines of the AC power supply connected to input end 3h and input end 3i, respectively. Further, the connection point between the capacitor 3b and the capacitor 3c is connected to the frame ground via the clamper 3e, and these are filter circuits 3j that suppress common mode noise of a relatively low frequency flowing in the first line and the second line. Is configured. On the other hand, the capacitor 3f and the capacitor 3g have a smaller capacity than the capacitors 3b and 3c, and constitute a filter circuit 3k that suppresses noise having a higher frequency than the filter circuit 3j. Capacitor 3b and capacitor 3c have a low impedance characteristic at a relatively low frequency, and capacitor 3f and capacitor 3g have a low impedance characteristic at a higher frequency than capacitors 3b and 3c.

  Thus, in the present invention, in the filter circuit 3j provided with the clamper 3e, the capacitor 30a for suppressing the noise of the relatively high frequency shown in FIG. 3 described in the background art is not connected to the clamper 3e, but a relatively low 5 MHz ( The filter circuit 3j that suppresses noise having a frequency of less than megahertz and a filter circuit 3k that suppresses noise having a relatively high frequency of 5 MHz or more are provided independently.

Next, the noise suppression effect of the conventional circuit shown in FIG. 3 and the circuit of the present application shown in FIG. 1 is compared based on actually measured data.
FIG. 4 shows the measurement result of the noise terminal voltage measured at the input end of the conventional circuit shown in FIG. In FIG. 4, the horizontal axis represents frequency, from 0.15 MHz to 30 MHz, and the vertical axis represents noise level unit: dB μV (Davy microvolt) where 1 μV (microvolt) is 0 decibel. The measurement conditions are as follows. Capacitors 3a and 3o have a capacitance of 3.3 μF (microfarad), common mode choke coil 3d has an inductance of 0.24 mH (millihenry), and capacitors 3b and 3c have a capacitance of 4700 PF (picofarad). The clamper 3e has a clamp voltage of 22V (volts) and the capacitor 30a has a capacity of 220PF.

  The graph of FIG. 4 shows the quasi-peak value of each noise voltage during FIG. 4 (1) heating operation and FIG. 4 (2) cooling operation. In the case of Class B of the VCCI standard in domestic air conditioners, The limit value of the quasi-peak value is 56 dBμV for 0.536 MHz to less than 5 MHz and 60 dBμV for 5 MHz to less than 30 MHz.

  FIG. 4 (1) During heating operation, the frequency is 56.6 dBμV which is closest to the standard limit value in the vicinity of 6 MHz. On the other hand, during the cooling operation in FIG. 4 (2), the frequency is 56.9 dBμV which is the closest to the standard limit value in the vicinity of 6 MHz.

  FIG. 2 shows the measurement result of the noise terminal voltage measured at the input terminal of the circuit of the present application shown in FIG. In FIG. 2, the horizontal axis represents the frequency, from 0.15 MHz to 30 MHz, and the vertical axis represents the noise level (unit: dBμV). The measurement conditions are as follows: the capacitors 3a and 3o have a capacitance of 3.3 μF, the common mode choke coil 3d has an inductance of 0.24 mH, the capacitors 3b and 3c have a capacitance of 4700 PF, the clamper 3e has a clamp voltage of 22 V, and the capacitor 3f. The capacity of the capacitor 3g is 220PF.

  The graph of FIG. 2 shows the quasi-peak value of each noise voltage during FIG. 2 (1) heating operation and FIG. 2 (2) cooling operation. In the case of Class B of the VCCI standard in domestic air conditioners, The limit value of the quasi-peak value is 56 dBμV for 0.536 MHz to less than 5 MHz and 60 dBμV for 5 MHz to less than 30 MHz.

  FIG. 2 (1) During heating operation, the frequency is 55.0 dBμV which is closest to the standard limit value in the vicinity of 6 MHz. On the other hand, at the time of the cooling operation in FIG. 2 (2), the frequency is 55.1 dBμV which is closest to the standard limit value in the vicinity of 6 MHz.

  2 and 4 are compared with each other in the heating operation and the cooling operation in the vicinity of 6 MHz. In the case of FIG. 2, that is, in the case of using the circuit of the present invention of FIG. 1, the case of using the conventional circuit of FIG. Even the noise voltage is suppressed. 56.6 dBμV (FIG. 4) −55.0 dBμV (FIG. 2) = 1.6 dBμV during heating operation, and 56.9 dBμV (FIG. 4) −55.1 dBμV (FIG. 2) = 1.8 dBμV during cooling operation. Thus, the effect of the present invention was confirmed.

  As described above, the capacitor connected in parallel to the clamper provided in the filter unit of the conventional air conditioner is deleted, and instead connected in series between the output terminal 3m and the output terminal 3n, the capacitor 3b Since the filter circuit 3k including the capacitors 3f and 3g having a smaller capacity than the capacitor 3c is provided independently, the circuit of this embodiment has a lower frequency than the filter unit of the conventional air conditioner described in FIG. Therefore, the common mode noise voltage can be suppressed over a wide range of high frequencies.

  On the other hand, in the filter unit 30 of the air conditioner described in the background art, the capacitor 3b and the capacitor 3c are targeted for relatively low frequency noise, and the capacitor 30a is targeted for relatively high frequency noise. For this reason, it is necessary to select the capacitance of each capacitor corresponding to the frequency of noise to be suppressed.

  When these capacitors are actually selected, even if the capacitor 30a is temporarily removed and the optimum capacity of the capacitor 3b and the capacitor 3c for suppressing noise of a relatively low frequency is determined, the capacitor 30a is additionally connected. As a result, the combined capacitance of the capacitor 30a, the capacitor 3b, and the capacitor 3c changes, and the characteristic of the noise suppression effect changes. Similarly, since the capacitor 30a is intended for relatively high frequency noise, it is necessary to determine the optimum value of the capacitor in consideration of the combined capacitance of the capacitor 30a, the capacitor 3b, and the capacitor 3c.

In this way, the filter unit 30 of the air conditioner described in the background art determines the value of each capacitor that achieves both a relatively low frequency noise suppression effect and a relatively high frequency noise suppression effect by cut-and-try. There was a need. For this reason, it has been difficult to make each capacitor have an optimum capacity.
In the present invention, the circuit is configured by separating the filter circuit 3j and the filter circuit 3k according to the frequency of the noise to be suppressed. Therefore, the optimum capacitor capacity is set according to the frequency of the noise to be reduced in each filter circuit. Easy to determine.

In this embodiment, a clamper is used to suppress the leakage current, but the present invention is not limited to this, and a constant voltage diode connected in series and in opposite directions may be used.
In this embodiment, the filter circuit 3j and the filter circuit 3k are connected in parallel to the output terminal 3m and the output terminal 3n. However, the present invention is not limited to this. Instead, the filter circuit 3j and the filter circuit 3k are input. Even if the end 3h and the input end 3i are connected in parallel, the same effect as the present embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 Air conditioner 3 Filter part 3a Capacitor 3b Capacitor (1st capacitor)
3c capacitor (second capacitor)
3d common mode choke coil 3e clamper 3f capacitor (third capacitor)
3g capacitor (4th capacitor)
3h Input terminal (first input terminal)
3i input terminal (second input terminal)
3j filter circuit (first filter circuit)
3k filter circuit (second filter circuit)
3m output terminal (first output terminal)
3n output terminal (second output terminal)
4 Rectifier 5 Boost Chopper Circuit 6 Inverter 7 Compressor 8 Outdoor Unit Control Unit 10 Outdoor Unit 20 Indoor Unit

Claims (1)

A filter unit having a first input terminal, a second input terminal, a first output terminal, and a second output terminal to which an AC power supply is connected, and is connected to the first output terminal and the second output terminal of the filter part. An air conditioner including a rectifier, an inverter driven using a DC power source output from the rectifier, and a compressor driven by the inverter and having a casing connected to a frame ground,
The filter unit is
A common mode choke coil connected in series between the first input end and the first output end, and between the second input end and the second output end;
A first filter circuit and a second filter circuit connected between the first output terminal and the second output terminal, or between the first input terminal and the second input terminal;
The first filter circuit includes a first capacitor and a second capacitor connected in series between the first output terminal and the second output terminal, a connection point between the first capacitor and the second capacitor, and the frame. It consists of a clamper connected between the ground and
The second filter circuit includes a third capacitor and a fourth capacitor that are connected in series between the first output terminal and the second output terminal, and that have a smaller capacity than the first capacitor and the second capacitor. A connection point between the third capacitor and the fourth capacitor and the frame ground are connected to each other.

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