Communication system of air conditioner

Abstract

The communication system of an air conditioner according to an embodiment is used for communication among a plurality of devices in an air conditioner in which the plurality of devices are connected through an AC power line and a single communication line. The air conditioner control circuit is configured to control the device, and the receiving circuit is configured to receive a communication signal transmitted via one of the communication line and the AC power supply line. The receiving circuit is provided with: a power supply circuit which is insulated from the air-conditioning control circuit and which generates a DC voltage based on an AC power supply line for transmitting the communication signal; a filter unit that extracts a voltage change in the communication signal; an amplification unit that uses the DC voltage as a power source and amplifies a signal output from the filter unit; and an insulation unit that insulates the signal output from the amplification unit and inputs the signal to the air-conditioning control circuit.

Description

Technical Field

[0001] Embodiments of the present invention relate to a system for communication between equipment rooms constituting an air conditioner. Background Art

[0002] Communication is carried out by wire between the equipment constituting the air conditioner and between multiple indoor units of the air conditioner. Usually, these devices are installed in separate locations, so the communication lines connecting the equipment rooms are relatively long. In addition, when the outdoor unit and each indoor unit are respectively connected to a common AC power supply, in order to reduce the number of wirings, one of the AC power lines is also used as a communication line. In such a communication environment, in order to reduce the influence of interference, it is desired to reduce the impedance of the communication circuit.

[0003] In communication using one of the AC power lines, the influence of the parasitic inductance of the wiring is small, and the parasitic capacitance and parasitic resistance become the main interference factors. Among them, the parasitic resistance generates a voltage amplitude proportional to the current flowing through one phase shared by the AC power supply. Therefore, in the case of sharing the wiring with a capacitor-input type load, a large amount of current flows only near the peak value of the power supply voltage. Through this current, a large-amplitude interference voltage is superimposed on the communication line. In addition, when high-order harmonic currents flow through the wiring, interference caused by the parasitic inductance component is also generated, but the interference caused by the parasitic resistance is dominant.

[0004] For example, in Patent Document 1, a switching element is used to reduce the impedance of the circuit. In addition, in Patent Documents 2 and 3, by connecting multiple devices using a constant current element, a reduction in noise margin is avoided.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent No. 3578134 Gazette

[0008] Patent Document 2: Japanese Patent No. 4419592 Gazette

[0009] Patent Document 3: Japanese Patent No. 4725199 Gazette Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] However, as in Patent Document 1, merely reducing the impedance of the circuit is effective for interference caused by parasitic capacitance, but has no effect on interference caused by parasitic resistance. In addition, in Patent Documents 2 and 3, since the circuit on the transmission side supplies power to a plurality of circuits on the reception side using a communication line, the entire power supply capacity of the opto-coupler for insulation that can drive the reception circuit located on the reception side is required. In addition, it is also necessary to add the transmission voltage required for driving the constant current element, and the noise radiated to the surroundings through communication becomes large. Furthermore, there is a problem of being vulnerable to interference noise caused by the above-mentioned parasitic resistance.

[0012] Therefore, a communication system for an air conditioner is provided that reduces the burden on the power supply capacity of the transmission side and is resistant to interference caused by either parasitic capacitance or parasitic resistance.

[0013] Means for Solving the Problem

[0014] In the communication system of the air conditioner according to the embodiment, in an air conditioner in which a plurality of devices are connected by an AC power line and one communication line, for communication between the plurality of devices, it is composed of an air conditioner control circuit for controlling the devices and a reception circuit for receiving the transmitted communication signal.

[0015] The receiving circuit includes: a power supply circuit, insulated from the air conditioner control circuit, generating a DC voltage based on the AC power line used for transmitting the communication signal; a filtering unit, extracting the voltage change of the communication signal; an amplifying unit, using the DC voltage as a power supply to amplify the signal output from the filtering unit; and an insulating unit, insulating and inputting the signal output from this amplifying unit to the air conditioner control circuit. Description of the Drawings

[0016] Figure 1 It is the first embodiment, and is a functional block diagram showing the configuration of an air conditioner with respect to parts related to power supply and communication.

[0017] Figure 2 It is a functional block diagram mainly showing the configuration of the communication devices provided in the outdoor unit and the indoor unit.

[0018] Figure 3 It is a functional block diagram showing the configuration of the air conditioner control circuit.

[0019] Figure 4 It is a functional block diagram showing the configuration of the receiving circuit of the communication device.

[0020] Figure 5 It is a diagram showing the frequency characteristics of the filtering unit of this receiving circuit.

[0021] Figure 6 It is a diagram showing the configuration of this receiving circuit with a specific circuit.

[0022] Figure 7 is a diagram showing the signal voltage waveforms of the respective parts of the receiving circuit.

[0023] Figure 8 is a diagram showing the input / output characteristics of the amplifying section of the receiving circuit. DETAILED DESCRIPTION

[0024] Hereinafter, an embodiment will be described. In Figure 1 , an outdoor unit 1 and a plurality of indoor units 2A, 2B, …, 2Z are connected by a single-phase 200V commercial AC power supply 3 and two power lines 4a, 4b. Further, the outdoor unit 1 and the plurality of indoor units 2A, 2B, …, 2Z are connected by a communication line 5. In addition, the AC power supply 3 may be a three-phase AC. In the case of using three-phase AC, three-phase AC is supplied to the outdoor unit 1 from three power lines, and two of the three power lines are connected to each indoor unit 2 to supply a single-phase AC voltage.

[0025] As Figure 2 shown, a communication device 6 provided in the outdoor unit 1 and each indoor unit 2 includes a power supply circuit 11, a transmission circuit 12, a receiving circuit 13, and an air-conditioning control circuit connection section 14. The air-conditioning control circuit connection section 14 is a wiring group that connects the communication device 6 to an air-conditioning control circuit 7 that controls the mounted equipment, that is, the outdoor unit 1 or the indoor unit 2. A power line 4a, a power line 4b, and a communication line 5 are connected to the communication device 6, and only the power lines 4a and 4b are connected to the air-conditioning control circuit 7. One power line 4b also serves as a communication line. The power supply circuit 11 converts the AC voltage of the AC power supply 3 supplied via the power lines 4a and 4b into a low-voltage DC.

[0026] As Figure 3 shown, the air-conditioning control circuit 7 includes: a rectifying circuit 71 that rectifies the AC voltage of the AC power supply 3 supplied via the AC power lines 4a, 4b, and is constituted by, for example, a full-wave rectifying circuit of a diode bridge; a capacitor 72 for smoothing, connected to the output of the rectifying circuit 71; and an inverter 74 that receives the smoothed DC output of the capacitor 72 and outputs a three-phase AC voltage for driving various motors 75 used in the air conditioner. In addition, the air-conditioning control circuit 7 includes: a motor 75 driven by the inverter 74; an inverter drive section 76 that drives the switching elements constituting the inverter 74; a main control section 77 that includes a microcomputer that controls the equipment incorporated in the outdoor unit 1 and the indoor units 2 to unify the control of the air conditioner; an air-conditioning DC power supply circuit 73 that serves as a low-voltage power supply; and its peripheral circuits. The motor 75 is a compressor motor and a motor for driving an outdoor fan in the outdoor unit 1, and is a motor for driving an indoor fan in the indoor unit 2.

[0027] The microcomputer in the air conditioner main control unit 77 has the function of receiving the communication signal shaped by the insulation unit 23 in the receiving circuit 13 and generating the signal transmitted via the transmitting circuit 12. Further, the DC power supply circuit 73 for the air conditioner is connected to the AC power supply lines 4a and 4b and supplied with the power of the AC power supply 3, but becomes a power supply insulated from the power supply circuit 11 on the communication circuit 6 side, that is, a DC power supply with different respective ground potentials. The DC power supply circuit 73 for the air conditioner supplies power to the inverter drive unit 76 and the main control unit 77, and further supplies power to a part of the insulation unit of the receiving circuit 13 described later.

[0028] In this way, a capacitor input type circuit having a rectifier circuit 71 and a smoothing capacitor 72 is provided in both the outdoor unit 1 and the indoor unit 2. Therefore, the current waveforms flowing through the power supply lines 4a and 4b are not sinusoidal waveforms imitating the voltage waveform, but distorted waveforms. Further, the outdoor unit 1 and the indoor unit 2 of the air conditioner are equipped with an inverter 74, which is a driving device for the motor of the compressor or the motor of the indoor fan, as a load of the capacitor input type circuit. The inverter 74 performs a high-frequency switching operation of several kHz, so high-order harmonic currents generated along with this switching operation also flow through the power supply lines 4a and 4b, becoming a noise source with respect to the communication signal.

[0029] By being connected to such an air conditioner control circuit 7, load currents of the air conditioner control circuit 7 flow through the power supply lines 4a and 4b. Due to the parasitic resistance components and inductance components of the power supply lines 4a and 4b, a back electromotive force is generated by the above load currents. The communication device 6 uses the power supply line 4b on one side of the communication line, so the amplitude of the communication signal decreases on the receiving side due to the back electromotive force of the load current. That is, the above back electromotive force becomes interference and affects the communication, so it is necessary to remove the interference.

[0030] The output DC voltage of the power supply circuit 11 that generates a DC voltage of X (V), for example, 16V, from the input AC power and supplies it as the operating power supply to the transmitting circuit 12 and the receiving circuit 13 is generated with the power supply line 4b, which is a phase of the AC power supply 3 and used for transmitting the communication signal, as the reference potential. The transmitting circuit 12 uses the communication line 5 and the power supply line 4b to transmit the signal input from the air conditioner control circuit 7 via the air conditioner control circuit connection part 14 to the receiving circuit 13. The communication performed between the transmitting circuit 12 and the receiving circuit 13 is serial communication, and the communication speed is, for example, 2400 bps.

[0031] As Figure 4 shown, the receiving circuit 13 includes a filtering unit 21, an amplifying unit 22, and an insulating unit 23. The filtering unit 21 extracts the change in the voltage of the communication line 5 and is, for example, a high-pass filter. As Figure 5As shown, the higher the frequency of the filtering unit 21, the greater the gain. It suppresses the frequency components of interference with relatively low suppression ratios and allows the frequency components of the communication signal in a higher frequency band to pass through.

[0032] In the Figure 6 that shows a more specific circuit configuration of the receiving circuit 13, the filtering unit 21 is a CR filter composed of a capacitor 31 and a resistance element 32. By using a CR filter, the circuit configuration can be simplified. The capacitor 31 is connected between the communication line 5 and the inverting input terminal of a comparator 33 that constitutes an amplifying unit 22 described later, and the resistance element 32 is connected between the inverting input terminal and the power supply line 4b.

[0033] Figure 7 It represents the input of the filtering unit 21 which is the input of the receiving circuit 13 for the communication signal, the output of the filtering unit 21 that inputs the communication signal, the input of the insulating unit 23 which is the output of the amplifying unit 22 that receives the output of the filtering unit 21 and amplifies it, and the output of the insulating unit 23 that supplies the output of the amplifier 22 to the air conditioner control circuit 7. From this figure, it can be seen that the signal voltage waveform flowing through the communication line 5 input to the filtering unit 21 becomes a waveform with interference superimposed with periodic fluctuations. Then, the output signal of the filtering unit 21 input with this waveform becomes a signal waveform in which the interference components are suppressed and the center potentials are consistent. The original communication signal uses voltages that are binary-coded as low and high in a specified period. At the output of the filtering unit 21, the time point when the communication signal rises from low to high becomes clear.

[0034] In the amplifying unit 22 that is input with the output signal of the above-mentioned filtering unit 21, a series circuit of resistance elements 34 and 35 is connected between the Y(V) output by the power supply circuit 11 and the ground on the receiving circuit 13 side, and the power supply line 4b is connected to this ground. The common connection point of the above-mentioned series circuit is connected to the non-inverting input terminal of the comparator 33.

[0035] A resistance element 36 is connected between the DC output of the power supply circuit 11 and the output terminal of the comparator 33, and a resistance element 37 is connected between the non-inverting input terminal and the output terminal. By imparting hysteresis characteristics using this feedback resistance, the amplifying unit 22 is configured as a hysteresis comparator. In addition, the amplification gain is set to about "8", for example.

[0036] Figure 8 It represents the input-output characteristics of the amplifying unit 22. By imparting hysteresis characteristics, only signals with an amplitude of a certain value or more of the output signal of the filtering unit 21 are amplified. As a result, interference superimposed on the amplitude that is difficult to separate in the filtering unit 21 can be removed. As a result, the output waveform of the amplifying unit 22 is Figure 7 shaped as shown and becomes a complete rectangular wave, restoring to a form in which the original transmitted signal can be clearly determined.

[0037] The insulating section 23 can be applied to various insulating elements and insulating circuits. However, in the present embodiment, as shown in Figure 6 , a photocoupler, which is a type of optical isolator with a simple circuit configuration, is used. A DC power supply of Y (V) supplied from the power supply circuit 11 of the communication circuit 6 and the output terminal of the comparator 33 are connected to the light-emitting diode on the input side. A DC power supply of X (V) and the ground on the side of the air conditioner control circuit 7 are connected to the phototransistor on the output side. X (V) is the voltage supplied from the DC power supply circuit 73 for the air conditioner provided on the side of the air conditioner control circuit 7, and uses the same AC power supply 3 as the power supply circuit 11 of the communication circuit 6, but becomes mutually insulated power supplies with different grounds. In the present embodiment, the voltages of the respective DC power supplies are Y = 16 (V) and X = 5 (V). Further, by passing through the insulating section 23, the receiving circuit 13 side and the air conditioner control circuit 7 side are insulated from each other.

[0038] As shown in Figure 7 , at the lowermost stage of the figure, the output waveform of the insulating section 23 becomes a form that inverts the output waveform of the amplifier 22 in the figure, and the high and low of the signal waveform can be clearly distinguished. Here, in the output waveform of the amplifier 22, there may sometimes be a very short pulse waveform (the P point in Figure 7 ), but due to the low responsiveness of the photocoupler constituting the insulating section 23, such a short-term pulse waveform is excluded from the output of the insulating section 23 and becomes a good waveform.

[0039] As described above, according to the present embodiment, in the air conditioner, the outdoor unit 1 and the indoor units 2A to 2Z are connected by the power supply lines 4a and 4b and the communication line 5, and the communication system is composed of an air conditioner control circuit 7, a transmission circuit 12 that transmits a communication signal via the communication line 5 and the power supply line 4b, and a receiving circuit 13 that receives the signal transmitted from the transmission circuit 12. The receiving circuit 13 includes: a power supply circuit 11, insulated from the air conditioner control circuit 7, generating a DC voltage based on the voltage of the power supply line 4b, which is a phase for transmitting the communication signal, in the AC power supply 3; a filtering section 21 that extracts the voltage change of the communication signal; an amplifying section 22 that amplifies the signal output from the filtering section 21 using the DC voltage as the power supply; and an insulating section 23 that insulates the signal output from the amplifying section 22 and inputs it to the air conditioner control circuit 7.

[0040] Thus, by providing the amplifier 22 for amplifying the received signal in the receiving circuit 13, the communication signal can be stably received even in an environment where the communication line 5 becomes longer and the amplitude of the communication signal decreases. In addition, the transmitting circuit 12 can be configured on the premise of the amplification in the amplifier 22 provided on the receiving side. Therefore, even when multiple communication devices 6 are connected to the same communication line 5 and receive signals from one transmitting circuit 12, the power supply capacity of the transmitting circuit 12 can be reduced, and the degree of freedom in component selection is increased.

[0041] Furthermore, if the amplification unit 22 is constituted by a hysteresis comparator, the interference superimposed on the amplitude that is difficult to separate in the filtering unit 21 can be removed, and the communication signal can be binarized.

[0042] (Other Embodiments)

[0043] The communication device 2 may also be applicable only to the communication between the indoor units 2.

[0044] When multiple outdoor units 1 are used, they can be connected by a communication line, or it can be applicable to the communication between the outdoor units 1.

[0045] The connection point to the AC power supply 3 can be either on the indoor unit 2 or the outdoor unit 1 side.

[0046] The characteristics of the filtering unit are not limited to a high-pass filter, and it can also be a low-pass filter, a band-pass filter, a band-stop filter, a notch filter, etc. according to the frequency components of the interference. In addition, when the amplification unit has the characteristic of removing noise, as the gain adjustment, the filtering unit can also be constituted by a resistor voltage division circuit.

[0047] The amplification unit can also be constituted by an operational amplifier.

[0048] The communication speed, the gain of the amplification unit, the voltage values X and Y can be appropriately changed according to individual designs.

[0049] Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments or their modifications are included in the scope or gist of the invention and are included in the invention described in the claims and its equivalents.

[0050] Description of Reference Numerals

[0051] 1 represents the outdoor unit, 2 represents the indoor unit, 3 represents the AC power supply, 4a and 4b represent the power lines, 5 represents the communication line, 6 represents the communication device, 7 represents the air conditioner control circuit, 11 represents the power supply circuit, 12 represents the transmission circuit, 13 represents the reception circuit, 14 represents the air conditioner control circuit connection part, 21 represents the filtering part, 22 represents the amplification part, 23 represents the insulation part, 31 represents the capacitor, 32 represents the resistance element, 71 represents the rectifier circuit, 72 represents the capacitor, 73 represents the DC power supply circuit for the air conditioner, 74 represents the inverter.

Claims

1. A communication system for an air conditioner, In an air conditioner connected by an AC power line and a communication line among multiple devices, for communication among the multiple devices, it is composed of an air conditioner control circuit for controlling the devices and a receiving circuit for receiving a communication signal sent via one of the communication line and the AC power line. The receiving circuit includes: A power supply circuit, insulated from the air conditioner control circuit, generating a DC voltage based on the AC power line for transmitting the communication signal. A filtering section, extracting the voltage change of the communication signal. An amplifying section, using the DC voltage as a power supply to amplify the signal output from the filtering section. And An insulating section, insulating and inputting the signal output from this amplifying section to the air conditioner control circuit.

2. The communication system for an air conditioner according to claim 1, The amplifying section has a hysteresis characteristic.

3. The communication system for an air conditioner according to claim 1, The filtering section is a high-pass filter composed of a capacitor and a resistor element.

4. The communication system for an air conditioner according to claim 1, The insulating section is composed of an optocoupler, Supplying power from the air conditioner control circuit to the phototransistor on the output side of the optocoupler.

5. The communication system for an air conditioner according to claim 1 includes: A transmitting circuit, which transmits the communication signal via one of the communication line and the AC power line.

6. The communication system for an air conditioner according to any one of claims 1 to 5, The air conditioner control circuit includes a rectifying circuit and an inverter, and the rectifying circuit is connected to the AC power line.

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