CN113606761A - Current loop communication circuit and air conditioner - Google Patents
Current loop communication circuit and air conditioner Download PDFInfo
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- CN113606761A CN113606761A CN202110976505.1A CN202110976505A CN113606761A CN 113606761 A CN113606761 A CN 113606761A CN 202110976505 A CN202110976505 A CN 202110976505A CN 113606761 A CN113606761 A CN 113606761A
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- communication circuit
- communication
- photoelectric coupler
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
- F24F11/63—Electronic processing
- F24F11/64—Electronic processing using pre-stored data
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/88—Electrical aspects, e.g. circuits
Abstract
The invention discloses a current loop communication circuit and an air conditioner, wherein the current loop communication circuit comprises: the first communication circuit and the second communication circuit share a zero line N, the first communication circuit and the second communication circuit are connected with a communication S line for communication, a discharge circuit is arranged between the communication S line and the zero line N, and parasitic capacitance generated between the communication S line and the zero line N is eliminated by the discharge circuit. According to the invention, when the first communication circuit and the second communication circuit are connected, high-level signal transmission between the first communication circuit and the second communication circuit is realized; when the first communication circuit sends a low-level signal to the second communication circuit, the parasitic capacitance is eliminated, the limitation of the current loop communication circuit on the length of the connecting line is reduced, and the communication distance is increased. Meanwhile, when the second communication circuit sends a low-level signal to the first communication circuit, a power supply boosting control method is adopted to pull up the voltage of the communication S line to the power supply voltage, so that the stability of the voltage of the communication S line is ensured.
Description
Technical Field
The invention relates to the field of communication, in particular to a current loop communication circuit and an air conditioner.
Background
At present, communication between an indoor unit and an outdoor unit of a household air conditioner is generally realized by adopting a current loop communication circuit, and the current loop communication is realized by three wires, namely a live wire L and a zero wire N of an alternating current power supply and an additional communication S wire. The indoor unit part and the outdoor unit part form a current loop communication circuit through a live wire L, a zero wire N and a communication S wire to realize the communication between the indoor unit and the outdoor unit of the air conditioner. The whole communication circuit has few connecting wires and low cost.
The current loop communication needs to share the zero line N with the power circuit, and in the actual installation and use process, the communication S line and the power line are mostly wired in parallel, the parallel wiring can generate parasitic capacitance, and the parasitic capacitance can influence the communication quality. For the same wire, when the connecting wire is short, the parasitic capacitance is small, and the influence of the charging and discharging of the parasitic capacitance on the level of the current loop communication S wire is small; when the connecting line is lengthened gradually, the parasitic capacitance is increased, the stored energy is enhanced, and the influence of charging and discharging on the level of the communication S line is increased; when the connecting line is added to a certain length, the level fluctuation caused by the charging and discharging of the parasitic capacitor can interfere the transmission of the effective level on the communication S line, thereby causing the communication failure. Therefore, the communication distance of the current loop communication circuit in the prior art is relatively short, and is usually only 30m-50 m.
Disclosure of Invention
The invention provides a current loop communication circuit and an air conditioner, aiming at solving the technical problem that the distance of a communication line is short due to parasitic capacitance existing when a power line and the communication line are wired in parallel in the prior art.
The technical scheme adopted by the invention is as follows:
the invention provides a current loop communication circuit and an air conditioner, wherein the current loop communication circuit comprises: the first communication circuit and the second communication circuit share a zero line N, and are connected with a communication S line for communication; particularly, a discharge circuit is arranged between the communication S line and the zero line N, and the discharge circuit eliminates parasitic capacitance between the communication S line and the zero line N.
Further, when the first communication circuit and the second communication circuit are connected, the discharging circuit does not work; when the first communication circuit and the second communication circuit are interrupted, the discharging circuit works.
Further, the discharge circuit includes: a forward discharge circuit and a reverse discharge circuit; when the voltage of the communication S line is greater than the voltage of the zero line N, the forward discharging circuit works; conversely, the reverse discharge circuit operates.
In an embodiment, when the voltage sent by the signal sending end of the first communication circuit or the second communication circuit is higher than or equal to a set high voltage value, a current flows between the first communication circuit and the second communication circuit; when the voltage sent by the signal sending end of the first communication circuit or the second communication circuit is lower than or equal to a set low voltage value, no current flow is interrupted between the first communication circuit and the second communication circuit.
Further, the current loop communication circuit further includes: a first power supply loop and a second power supply loop sharing a power line L; the first power supply loop is connected with the first communication circuit and supplies power to the first communication circuit; and the second power supply loop is connected with the second communication circuit and supplies power to the second communication circuit.
In one embodiment, a pull-up circuit is arranged between the second power supply loop and the second communication circuit; when the voltage output by the second communication circuit is lower than or equal to a set low voltage value, the pull-up circuit works to pull up the voltage of the communication S line to the output voltage of the second power supply loop, and the voltage of the communication S line is fixed to be unchanged.
In one embodiment, the forward discharge circuit includes: a resistor R14 and a photoelectric coupler PC 11; one end of the resistor R14 is connected with the communication S line, the other end of the resistor R14 is connected with the collector of the photoelectric coupler PC11, the emitter of the photoelectric coupler PC11 is connected with the zero line N, and the light emitting diode of the photoelectric coupler PC11 is connected with the signal sending end of the first communication circuit.
In one embodiment, the reverse discharge circuit includes: a diode D5; the anode of the diode D5 is connected with the neutral wire N, and the cathode of the diode D5 is connected with the communication S wire.
In one embodiment, the pull-up circuit includes: a photocoupler PC 21; a collector of the photoelectric coupler PC21 is connected to an output terminal of the second power supply loop, an emitter of the photoelectric coupler PC21 is connected to the communication S line, and a light emitting diode of the photoelectric coupler PC21 is connected to a signal transmitting terminal of the second communication circuit.
In one embodiment, the first communication circuit includes: a photoelectric coupler PC10, a photoelectric coupler PC12, a diode D4, a resistor R13, a resistor R2 and a diode D6; the collector of the triode of the photoelectric coupler PC10 is connected with a first power supply loop, the emitter of the triode of the photoelectric coupler PC10 is connected with the anode of the light emitting diode of the photoelectric coupler PC12, the cathode of the light emitting diode of the photoelectric coupler PC12 is sequentially connected with the anode of the resistor R2 and the anode of the diode D6 in series, meanwhile, the cathode of the light emitting diode of the positive photoelectric coupler PC12 of the diode D4, the cathode of the diode D4 is connected with the anode of the light emitting diode of the photoelectric coupler PC12, and the resistor R13 is connected with two ends of the diode D4 in parallel.
In one embodiment, the second communication circuit includes: a photoelectric coupler PC20, a photoelectric coupler PC22, a diode D9, a resistor R20, a diode D8, a resistor R15 and a resistor R17; the collector of the photoelectric coupler PC20 is sequentially connected in series with the negative electrodes of a resistor R15 and a diode D8, one end of the resistor R17 is connected between the resistor R15 and the collector of the photoelectric coupler PC20, the other end of the resistor R17 is connected with the emitter of the photoelectric coupler PC20, the emitter of the photoelectric coupler PC20 is connected with the positive electrode of the light emitting diode of the photoelectric coupler PC22, the negative electrode of the light emitting diode of the photoelectric coupler PC22 is connected with the zero line N, the positive electrode of the diode D9 is connected with the negative electrode of the light emitting diode of the photoelectric coupler PC22, the negative electrode of the diode D9 is connected with the positive electrode of the light emitting diode of the photoelectric coupler PC22, and the resistor R20 is connected in parallel with the two ends of the diode D9.
In one embodiment, when the voltage transmitted by the signal transmitting end of the first communication circuit is higher than or equal to a set high voltage value, the photocouplers PC10 and PC22 are turned on; when the voltage transmitted by the signal transmitting end of the second communication circuit is higher than or equal to a set high voltage value, the photocoupler PC20, the photocoupler PC10 and the photocoupler PC12 are turned on.
An air conditioner, comprising: the indoor unit is provided with the first communication circuit, the outdoor unit is provided with the second communication circuit, and the indoor unit and the outdoor unit are communicated by using the current loop communication circuit.
In one embodiment, when the voltage sent by the indoor unit is lower than or equal to a set low voltage value, the outdoor unit receives a low level signal; when the voltage sent by the indoor unit is higher than or equal to a set high voltage value, the outdoor unit receives a high level signal; when the voltage sent by the outdoor unit is lower than or equal to a set low voltage value, the indoor unit receives a low level signal; and when the voltage sent by the outdoor unit is higher than or equal to a set high voltage value, the indoor unit receives a high level signal.
Compared with the prior art, the invention realizes double-loop control: when the first communication circuit and the second communication circuit carry out high-level transmission, the first communication circuit and the second communication circuit are connected to form a communication loop, so that high-level signal transmission between the first communication circuit and the second communication circuit is realized; when the first communication circuit sends a low-level signal to the second communication circuit, the parasitic capacitance is eliminated, and the communication distance is increased. Meanwhile, the invention also adopts a power supply boosting control method, when the second communication circuit sends a low-level signal to the first communication circuit, the voltage of the communication S line is boosted to the power supply voltage, and the stability of the voltage of the communication S line is ensured.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1 is a schematic diagram of the overall structure of the present invention;
FIG. 2 is a schematic diagram of the overall structure in an embodiment of the present invention;
FIGS. 3-5 are specific circuit diagrams of embodiments of the present invention;
FIG. 6 is a specific circuit diagram of another embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Because the industrial control application often involves long-distance accurate transmission of data or control signals, and the current is used as a carrier to transmit data, the noise tolerance of the signals can be increased, and the anti-attenuation capability of the signals can be improved. The current loop communication circuit for carrying signals on a current loop to realize long-distance signal transmission often shares the current loop with a zero line of an alternating current power supply to form a common-zero-line current loop communication circuit. The current loop communication circuit has wide application due to its advantages. In the prior art, because the indoor unit and the outdoor unit of the air conditioner are far away from each other, a current loop communication circuit with a common zero line is often adopted for communication.
In order to facilitate understanding of the principle of the present invention, the current loop communication circuit provided by the present invention is particularly applied to the communication situations of the indoor unit and the outdoor unit of the air conditioner, and the present invention is explained with reference to the usage scenario, but the usage scenario is not a limitation to the present invention, and the current loop communication circuit provided by the present invention may also be applied to other situations.
The communication between the indoor unit and the outdoor unit of the air conditioner is generally realized by adopting a current loop communication circuit, and the current loop communication is realized by three wires, namely a live wire L and a zero wire N of an alternating current power supply and an additional communication wire. However, the current loop communication needs to share the zero line N with the power circuit supplying power to the current loop communication circuit, and in the actual installation and use process, the communication S line and the power line are mostly wired in parallel, and the parallel wiring will generate parasitic capacitance, which will affect the communication distance.
The invention provides a current loop communication circuit, aiming at solving the problem that parasitic capacitance generated by parallel wiring of a zero line N and a communication S line influences the communication distance in the prior art.
The principles and construction of the present invention will be described in detail below with reference to the drawings and examples.
The present invention provides a current loop communication circuit, as shown in fig. 1, including: the communication device comprises a first communication circuit and a second communication circuit, wherein an alternating current power supply live wire L, a zero wire N and a communication S wire are connected between the first communication circuit and the second communication circuit, so that communication is realized. Meanwhile, a discharge circuit is connected between the zero line N and the communication S line. When the first communication circuit and the second communication circuit are connected, the discharge circuit does not work due to the fact that the communication circuit has large effective communication current, the anti-interference capability is strong, and the influence of parasitic capacitance is small; when the first communication circuit and the second communication circuit are interrupted, the voltage inequality between the communication S line and the zero line N is influenced by the voltage fluctuation of the power line live wire L, and the discharging circuit works. The current loop communication circuit provided by the invention eliminates the parasitic capacitance generated between the communication S line and the zero line N, improves the communication quality and increases the communication distance.
As shown in fig. 2, in the present embodiment, specifically: the first communication circuit is connected with a first power supply loop, the second communication circuit is connected with a second power supply loop, and the first power supply loop and the second power supply loop share a zero line N and a live line L so as to supply power for the first communication circuit and the second communication circuit. And a communication S line is connected between the first communication circuit and the second communication circuit, so that the first communication circuit, the second communication circuit, the first power supply loop and the second power supply loop can form a complete circuit loop. Meanwhile, the first power supply loop, the second power supply loop and the communication S line share a zero line N, and a discharge circuit is connected between the communication S line and the zero line N. Because the first communication circuit and the second communication circuit realize remote communication, the first power supply loop and the second power supply loop are arranged to respectively supply power to the first communication circuit and the second communication circuit, the practical requirement and the use condition are met, and the communication control is convenient to realize.
In the present invention, the discharge circuit is further specifically configured as: a forward discharge circuit and a reverse discharge circuit. If the voltage of the communication S line is higher than the voltage of the zero line N, the forward discharging circuit works to level the voltage of the communication S line and the voltage of the zero line N; if the voltage of the communication S line is lower than the voltage of the zero line N, the reverse discharge circuit works to level the voltage of the communication S line and the voltage of the zero line. The design of two one-way conduction discharge circuits has high reliability and strong practicability, and can more accurately and more quickly find whether the discharge circuit breaks down. If one of the discharge circuits is in fault, the other discharge circuit can still be used, so that when only one discharge circuit works for a long time, a prompt can be given to a user to remind the user to detect and timely eliminate the fault.
According to the specific functions and requirements of the current loop-through circuit, the invention designs a specific circuit which is simple and convenient for practical use.
As shown in fig. 3, the first communication circuit includes: a photoelectric coupler PC10, a photoelectric coupler PC12, a diode D4, a resistor R13, a resistor R2 and a diode D6; the collector of the triode of the photoelectric coupler PC10 is connected with a first power supply loop, the emitter of the triode of the photoelectric coupler PC10 is connected with the anode of the light emitting diode of the photoelectric coupler PC12, the cathode of the light emitting diode of the photoelectric coupler PC12 is sequentially connected with the anode of the resistor R2 and the anode of the diode D6 in series, meanwhile, the cathode of the light emitting diode of the positive photoelectric coupler PC12 of the diode D4, the cathode of the diode D4 is connected with the anode of the light emitting diode of the photoelectric coupler PC12, and the resistor R13 is connected with two ends of the diode D4 in parallel.
As shown in fig. 3, the second communication circuit includes: a photoelectric coupler PC20, a photoelectric coupler PC22, a diode D9, a resistor R20, a diode D8, a resistor R15 and a resistor R17; the collector of the photoelectric coupler PC20 is sequentially connected in series with the negative electrodes of a resistor R15 and a diode D8, one end of the resistor R17 is connected between the resistor R15 and the collector of the photoelectric coupler PC20, the other end of the resistor R17 is connected with the emitter of the photoelectric coupler PC20, the emitter of the photoelectric coupler PC20 is connected with the positive electrode of the light emitting diode of the photoelectric coupler PC22, the negative electrode of the light emitting diode of the photoelectric coupler PC22 is connected with the zero line N, the positive electrode of the diode D9 is connected with the negative electrode of the light emitting diode of the photoelectric coupler PC22, the negative electrode of the diode D9 is connected with the positive electrode of the light emitting diode of the photoelectric coupler PC22, and the resistor R20 is connected in parallel with the two ends of the diode D9.
And a communication S line is connected between the cathode of the diode D6 and the anode of the diode D8, so that the first communication circuit is connected with the inner machine communication circuit to form a complete loop.
As shown in fig. 4, the forward discharge circuit includes: a parasitic capacitor C2, a resistor R14 and a photoelectric coupler PC11 are generated between the communication S line and the zero line N; the reverse discharge circuit includes: the circuit comprises a parasitic capacitor C2 and a diode D5, wherein one end of a resistor R14 is connected with a communication S line, the other end of the resistor R14 is connected with a collector of a photoelectric coupler PC11, an emitter of the photoelectric coupler PC11 is connected with a zero line N, a cathode of a diode D5 is connected with the communication S line, and an anode of a diode D5 is connected with the zero line N.
Meanwhile, as shown in fig. 5, in the present embodiment, the first power supply loop includes: the circuit comprises a resistor R1, a diode D1, a capacitor C1, a resistor R4, a diode D2 and a clamping diode D3; the second power supply loop includes: the circuit comprises a resistor R27, a diode D10, a capacitor C3, a resistor R26, a diode D12 and a clamping diode D11; one end of the resistor R1 is connected with the live wire L, and the other end of the resistor R1 is connected with the anode of the diode D1; the capacitor C1, the resistor R4, the diode D2 and the clamping diode D3 are connected in parallel, one end of the capacitor is connected with the negative electrode of the diode D1, the other end of the capacitor is connected with the zero line N, specifically, the negative electrodes of the diode D2 and the clamping diode D3 are connected with the negative electrode of the diode D1, and the positive electrodes of the diode D2 and the clamping diode D3 are connected with the zero line N. One end of the resistor R27 is connected with the live wire L, and the other end of the resistor R27 is connected with the anode of the diode D10; the capacitor C3, the resistor R26, the diode D12 and the clamping diode D11 are connected in parallel, one end of the capacitor is connected with the negative electrode of the diode D10, the other end of the capacitor is connected with the zero line N, specifically, the negative electrodes of the diode D12 and the clamping diode D11 are connected with the negative electrode of the diode D10, and the positive electrodes of the diode D12 and the clamping diode D11 are connected with the zero line N.
Because the first power supply loop supplies power to the first communication circuit, the collector of the triode of the photoelectric coupler PC10 is connected with the capacitor C1 and between the capacitor C1 and the diode D1; similarly, the second power supply loop supplies power to the second communication circuit, a photoelectric coupler PC21 is connected between the second power supply loop and the second communication circuit, a collector of a triode of the photoelectric coupler PC21 is connected between the capacitor C3 and the diode D10, an emitter of the photoelectric coupler PC21 is connected with the anode of the diode D8, and the photoelectric coupler PC21 is kept to be conducted when the second communication circuit works, so that the second power supply loop can supply power to the second communication circuit.
Meanwhile, in consideration of circuit practicability, corresponding control circuits need to be designed at the signal sending end and the signal receiving end of the first communication circuit and the second communication circuit. In the actual use process, the communication between the first communication circuit and the second communication circuit is realized by controlling the control circuit. As shown in fig. 3, in the present embodiment, specifically:
a signal transmitting terminal TX of the first communication circuit simultaneously controls a photoelectric coupler PC10 and a photoelectric coupler PC11, and a signal receiving terminal RX is connected with the photoelectric coupler PC 12. The positive electrode of a light emitting diode of the photoelectric coupler PC10 is sequentially connected with resistors R3 and VCC, the negative electrode of the light emitting diode of the photoelectric coupler PC10 is connected with the collector of a switch tube Q1, the base of the switch tube Q1 is connected with a resistor R5, a resistor R5 is connected with a signal sending end TX, and the emitter of the switch tube Q1 is grounded; the positive electrode of a light emitting diode of the photoelectric coupler PC11 is connected with the collector of a switch tube Q2, the base of a switch tube Q2 is connected with a resistor R7, the resistor R7 is connected with a signal sending end, a resistor R8 is connected between the base and the emitter of a switch tube Q2, the emitter of the switch tube Q2 is connected with VCC, and the negative electrode of the light emitting diode of the photoelectric coupler PC11 is connected with a resistor R9 and then grounded. The collecting electrode of the triode of the photoelectric coupler PC12 is connected with the signal receiving end, the collecting electrode of the triode of the photoelectric coupler PC12 is also connected with a resistor R11, the other end of the resistor R11 is connected with VCC, and the emitting electrode of the photoelectric coupler PC12 is grounded. The switch tube Q1 is an NPN transistor, and the switch tube Q2 is a PNP transistor.
And a signal transmitting end TXD of the second communication circuit simultaneously controls a photoelectric coupler PC21 and a photoelectric coupler PC20, and a signal receiving end RXD is connected with the photoelectric coupler PC 22. The positive electrode of a light emitting diode of the photoelectric coupler PC21 is connected with the collector electrode of a switch tube Q4, the base electrode of a switch tube Q4 is connected with a resistor R24, the other end of the resistor R24 is connected with a signal sending end TXD, the emitter electrode of a switch tube Q4 is connected with VCC, a resistor R23 is connected between the emitter electrode and the base electrode of a switch tube Q4, and the negative electrode of the light emitting diode of the photoelectric coupler PC21 is connected with a resistor R25 and then grounded. The positive electrode of a light emitting diode of the photoelectric coupler PC20 is connected with the resistor R16 and then is connected with VCC, the negative electrode of the light emitting diode of the photoelectric coupler PC20 is connected with the collector of the switch tube Q3, the base of the switch tube Q3 is connected with the resistor R18, the other end of the resistor R18 is connected with a signal sending end TXD, and the emitter of the switch tube Q3 is grounded. The emitter of the triode of the photoelectric coupler PC22 is grounded, the collector of the triode of the photoelectric coupler PC22 is connected with the signal receiving terminal RXD, the collector of the photoelectric coupler PC22 is connected with the resistor R21, and the other end of the resistor 21 is connected with VCC. The switch tube Q3 is an NPN transistor, and the switch tube Q4 is a PNP transistor.
The above is a specific circuit, and the communication principle is explained below with reference to the specific circuit.
Firstly, it should be clear that in this embodiment, the current loop communication circuit transmits digital signals, and according to the design of this embodiment, the voltage value of VCC is specified as a set high voltage value, and a high level signal is obtained when the voltage values of the signal transmitting terminal TX, the signal transmitting terminal TXD, the signal receiving terminal RX, and the signal receiving terminal RXD are higher than or equal to the set high voltage value; the specified voltage value 0 bit sets a low voltage value, and the low level signal is obtained when the voltage values of the signal transmitting terminal TX, the signal transmitting terminal TXD, the signal receiving terminal RX and the signal receiving terminal RXD are lower than or equal to the set low voltage value. The digital signal transmission can simplify the control of the current loop communication circuit and can prevent the components in the circuit from being in a state of misconduction when the input voltage is between a set high voltage value and a set low voltage value.
When the signal transmitting end TX of the first communication circuit transmits a high level signal, the switching tube Q1 is turned on, the switching tube Q2 is turned off, and thus the photocoupler PC10 is turned on and the photocoupler PC11 is turned off. Meanwhile, the signal sending end of the second communication circuit is controlled to keep a high level to control the photoelectric coupler PC20 to keep a conducting state unchanged (when the photoelectric coupler PC20 is conducted, the resistor R17 is short-circuited, the current of the current loop communication circuit is increased, and the conducting voltage drop of a light emitting diode of the photoelectric coupler PC22 is met). At this time, the second communication circuit and the first communication circuit are connected to form a communication loop, and a communication current flows from the capacitor C1 through the photocoupler PC10, the photocoupler PC12, the resistor R2 and the diode D6 in sequence, then flows into the diode D8, the resistor R15 and the photocoupler PC20 of the second communication circuit along the communication S line and returns to the zero line N, so that the signal receiving end RXD of the second communication circuit can receive a high-level signal, and signal transmission between the first communication circuit and the second communication circuit is realized.
Meanwhile, when a signal sending end TX of the first communication circuit sends a high-level signal, the second communication circuit and the first communication circuit form a communicated communication loop, the circuit current is large, and the influence of voltage fluctuation of a live wire L on the communication level can be almost ignored. At this time, the forward discharge circuit and the reverse discharge circuit do not operate.
When the signal transmitting end TX of the first communication circuit transmits a low level signal, the switching tube Q2 is turned on, the switching tube Q1 is turned off, and thus the photocoupler PC10 is turned off and the photocoupler PC11 is turned on. Meanwhile, the signal sending end TXD of the second communication circuit is controlled to keep a high level to control the photoelectric coupler PC20 to keep a conducting state unchanged (because the invention transmits high and low level signals, if the photoelectric coupler PC20 is not controlled to be conducted, the signal sending end TXD is a low level signal to lead the photoelectric coupler PC21 to be conducted, so that the voltage of a communication S line is pulled to the voltage of a capacitor C3 to influence the communication). At this time, the first communication circuit and the second communication circuit are interrupted, and the receiving terminal RXD of the second communication circuit receives a low level signal.
When a signal sending end TX of a first communication circuit sends a low-level signal, if a parasitic capacitor C2 is influenced by voltage fluctuation of a power line live wire L and is in a charging state, at the moment, the voltage of a communication S line is higher than the voltage of a zero line N, a forward discharging circuit is conducted, the parasitic capacitor C2 can discharge through the forward discharging circuit, current starts from the communication S line, sequentially flows through a resistor R14 and a photoelectric coupler PC11, then returns to the zero line N until the voltage of the communication S line and the voltage of the zero line N are leveled, and the forward discharging circuit is disconnected. If the parasitic capacitor C2 is in a discharging state under the influence of voltage fluctuation of a power line live wire L, at the moment, the voltage of a communication S line is lower than the voltage of a zero line N, the reverse discharging circuit is conducted, the parasitic capacitor C2 can discharge through the reverse discharging circuit, current starts from the zero line N, flows through the diode D5 and then returns to the communication S line until the voltage of the communication S line is equal to the voltage of the zero line N, and the reverse discharging circuit is disconnected.
When the signal transmitting end TXD of the second communication circuit transmits a high level signal, the switching tube Q3 is turned on, the switching tube Q4 is turned off, and thus the photoelectric coupler PC20 is turned on and the photoelectric coupler PC21 is turned off. Meanwhile, a signal sending end TX of the first communication circuit outputs a high level to control the conduction of a photoelectric coupler PC 10. At this time, the second communication circuit and the first communication circuit are connected to form a communication loop, and a level signal can be transmitted among the photocoupler PC10, the photocoupler PC12, the resistor R2, the diode D6, the communication S line, the diode D8, the resistor R15, and the photocoupler PC20, so that the signal receiving terminal RX of the first communication circuit can receive a high level signal. Namely, signal transmission and information transmission are realized between the second communication circuit and the first communication circuit.
Meanwhile, when the signal sending end TXD of the second communication circuit sends a high-level signal, the first communication circuit and the first communication circuit form a communicated communication loop, the circuit current is large, and the influence of the voltage fluctuation of the live wire L on the communication level can be almost ignored. At this time, the forward discharge circuit and the reverse discharge circuit do not operate.
When the signal transmitting end TXD of the second communication circuit transmits a low level signal, the switching tube Q3 is cut off, the switching tube Q4 is conducted, and therefore the photoelectric coupler PC21 is conducted and the photoelectric coupler PC20 is disconnected. Meanwhile, a signal sending end TX of the first communication circuit outputs a high level to control the conduction of a photoelectric coupler PC 10. At this time, a conductive loop cannot be formed between the second communication circuit and the first communication circuit, and the receiving terminal RX of the first communication circuit receives a low-level signal at this time.
When the signal transmitting terminal TXD of the second communication circuit transmits a low-level signal, the parasitic capacitor C2 is in a charge-discharge state under the influence of voltage fluctuation of the power line live wire L, but because the photoelectric coupler PC11 is turned off at this time, the forward discharge circuit does not work, and the influence of the voltage of the parasitic capacitor C2 cannot be eliminated. In view of this problem, the present invention designs a pull-up circuit, namely, a photo-coupler PC 21. Since the photocoupler PC21 is turned on when the signal transmitting terminal TXD of the second communication circuit transmits a low level signal, the voltage of the communication S line is pulled up to the voltage of the capacitor C3, and the voltage of the communication S line is fixed to the voltage of the capacitor C3, so that the voltage of the communication S line is not affected by the charging and discharging of the parasitic capacitor C2. Under the condition, the voltage of the communication S line is greater than the voltage of the zero line N, and even if the forward discharge circuit and the reverse discharge circuit do not work at the moment, the communication process cannot be influenced, and the anti-interference capability of communication is provided. Meanwhile, since the photocoupler PC10 is also turned on at this time, the photocoupler PC12 may be turned on erroneously, and in order to prevent this, it is ensured that the voltage of the capacitor C3 is not lower than the voltage of the capacitor C1 when designing the circuit parameters.
In summary, the first aspect of the present invention is to realize dual loop control: when the first communication circuit and the second communication circuit carry out high-level transmission, the first communication circuit and the second communication circuit are connected to form a communication loop, so that high-level signal transmission between the first communication circuit and the second communication circuit is realized; when the first communication circuit sends a low-level signal to the second communication circuit, the voltage generated by the parasitic capacitor C2 is eliminated, the limitation of the length of the connecting wire on current loop communication is reduced, and the communication distance is increased. Secondly, the invention adopts a power supply boosting control method, and when the second communication circuit sends a low level signal to the first communication circuit, the optical coupler is adopted to pull up the communication S line to the power supply voltage, thereby ensuring the stability of the level of the communication S line.
The invention also provides an air conditioner, which comprises an indoor unit and an outdoor unit, wherein the signal receiving end and the signal transmitting end of the second communication circuit are connected with the indoor unit, the signal receiving end and the signal transmitting end of the first communication circuit are connected with the outdoor unit, and further the indoor unit and the outdoor unit transmit signals through the current loop communication circuit. The outdoor unit receives a low level signal when the indoor unit sends the low level signal, and receives a high level signal when the indoor unit sends the high level signal; the indoor unit receives a low level signal when the outdoor unit transmits the low level signal, and the indoor unit receives a high level signal when the outdoor unit transmits the high level signal.
In another embodiment, the diode D5 in fig. 3 can be directly eliminated, and in this embodiment, the reverse discharging circuit is eliminated, and the discharging of the neutral wire N to the communication S line through the diode D5 cannot be realized. However, in practical use, communication is not affected, but a negative value appears in a low-level waveform of communication, which is not beneficial to analysis and processing of data in the test and verification process, the circuit diagram after modification is shown in fig. 6, and the communication principle is consistent with the above description. In other embodiments, the switching transistors Q1-Q4 may be replaced by switching devices such as MOSFET transistors with the same switching control function, and the photocoupler may also be replaced by any optoelectronic isolation device.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (14)
1. A current loop communication circuit, comprising: the first communication circuit and the second communication circuit share a zero line N, and are connected with a communication S line for communication; the high-voltage power supply is characterized in that a discharging circuit is arranged between the communication S line and the zero line N, and the discharging circuit eliminates parasitic capacitance between the communication S line and the zero line N.
2. The current loop communication circuit of claim 1, wherein said discharge circuit is not operational when said first communication circuit and said second communication circuit are on; when the first communication circuit and the second communication circuit are interrupted, the discharging circuit works.
3. The current loop communication circuit according to claim 2, wherein when the voltage sent by the signal sending end of the first communication circuit or the second communication circuit is higher than or equal to a set high voltage value, a current flows between the first communication circuit and the second communication circuit; when the voltage sent by the signal sending end of the first communication circuit or the second communication circuit is lower than or equal to a set low voltage value, no current flow is interrupted between the first communication circuit and the second communication circuit.
4. The current loop communication circuit of claim 1, wherein the discharge circuit comprises: a forward discharge circuit and a reverse discharge circuit; when the voltage of the communication S line is greater than the voltage of the zero line N, the forward discharging circuit works; conversely, the reverse discharge circuit operates.
5. The current loop communication circuit of claim 1, further comprising: a first power supply loop and a second power supply loop sharing a power line L; the first power supply loop is connected with the first communication circuit and supplies power to the first communication circuit; and the second power supply loop is connected with the second communication circuit and supplies power to the second communication circuit.
6. The current loop communication circuit of claim 5, wherein a pull-up circuit is disposed between the second power loop and the second communication circuit; when the voltage sent by the signal sending end of the second communication circuit is lower than or equal to a set low voltage value, the pull-up circuit works to pull up the voltage of the communication S line to the output voltage of the second power supply loop, and the voltage of the communication S line is fixed to be unchanged.
7. The current loop communication circuit of claim 4, wherein the forward discharge circuit comprises: a resistor R14 and a photoelectric coupler PC 11; one end of the resistor R14 is connected with the communication S line, the other end of the resistor R14 is connected with the collector of the photoelectric coupler PC11, the emitter of the photoelectric coupler PC11 is connected with the zero line N, and the light emitting diode of the photoelectric coupler PC11 is connected with the signal sending end of the first communication circuit.
8. The current loop communication circuit of claim 4, wherein the reverse discharge circuit comprises: a diode D5; the anode of the diode D5 is connected with the neutral wire N, and the cathode of the diode D5 is connected with the communication S wire.
9. The current loop communication circuit of claim 6, wherein the pull-up circuit comprises: a photocoupler PC 21; a collector of the photoelectric coupler PC21 is connected to an output terminal of the second power supply loop, an emitter of the photoelectric coupler PC21 is connected to the communication S line, and a light emitting diode of the photoelectric coupler PC21 is connected to a signal transmitting terminal of the second communication circuit.
10. A current loop communication circuit according to claim 3, wherein the first communication circuit comprises: a photoelectric coupler PC10, a photoelectric coupler PC12, a diode D4, a resistor R13, a resistor R2 and a diode D6; the negative electrode of a light emitting diode of the photoelectric coupler PC10 is connected with the signal sending end of the first communication circuit, and the collector electrode of a triode of the photoelectric coupler PC12 is connected with the signal receiving end of the first communication circuit; the collector of the triode of the photoelectric coupler PC10 is connected with a first power supply loop, the emitter of the triode of the photoelectric coupler PC10 is connected with the anode of the light emitting diode of the photoelectric coupler PC12, the cathode of the light emitting diode of the photoelectric coupler PC12 is sequentially connected with the anode of the resistor R2 and the anode of the diode D6 in series, the anode of the diode D4 is connected with the cathode of the light emitting diode of the photoelectric coupler PC12, the cathode of the diode D4 is connected with the anode of the light emitting diode of the photoelectric coupler PC12, the resistor R13 is connected with two ends of the diode D4 in parallel, and the emitter of the triode of the photoelectric coupler PC12 is grounded.
11. The current loop communication circuit of claim 10, wherein said second communication circuit comprises: a photoelectric coupler PC20, a photoelectric coupler PC22, a diode D9, a resistor R20, a diode D8, a resistor R15 and a resistor R17; the negative electrode of a light emitting diode of the photoelectric coupler PC20 is connected with the signal sending end of the second communication circuit, and the collector electrode of a triode of the photoelectric coupler PC22 is connected with the signal receiving end of the second communication circuit; the collector of the photoelectric coupler PC20 is sequentially connected in series with the negative electrodes of a resistor R15 and a diode D8, one end of the resistor R17 is connected between the resistor R15 and the collector of the photoelectric coupler PC20, the other end of the resistor R17 is connected with the emitter of the photoelectric coupler PC20, the emitter of the photoelectric coupler PC20 is connected with the positive electrode of the light emitting diode of the photoelectric coupler PC22, the negative electrode of the light emitting diode of the photoelectric coupler PC22 is connected with the zero line N, the positive electrode of the diode D9 is connected with the negative electrode of the light emitting diode of the photoelectric coupler PC22, the negative electrode of the diode D9 is connected with the positive electrode of the light emitting diode of the photoelectric coupler PC22, the resistor R20 is connected in parallel with the two ends of the diode D9, and the emitter of the triode of the photoelectric coupler PC22 is grounded.
12. The current loop communication circuit of claim 11, wherein when the voltage sent by the signal sending end of the first communication circuit is higher than or equal to a set high voltage value, the photo coupler PC10, the photo coupler PC22 are turned on; when the voltage transmitted by the signal transmitting end of the second communication circuit is higher than or equal to a set high voltage value, the photocoupler PC20, the photocoupler PC10 and the photocoupler PC12 are turned on.
13. An air conditioner, comprising: indoor unit provided with said first communication circuit, outdoor unit provided with said second communication circuit, characterized in that said indoor unit and said outdoor unit communicate using a current loop communication circuit according to any of claims 1-12.
14. The air conditioner of claim 13, wherein the outdoor unit receives a low level signal when the voltage transmitted from the indoor unit is lower than or equal to a set low voltage value; when the voltage sent by the indoor unit is higher than or equal to a set high voltage value, the outdoor unit receives a high level signal; when the voltage sent by the outdoor unit is lower than or equal to a set low voltage value, the indoor unit receives a low level signal; and when the voltage sent by the outdoor unit is higher than or equal to a set high voltage value, the indoor unit receives a high level signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110976505.1A CN113606761A (en) | 2021-08-24 | 2021-08-24 | Current loop communication circuit and air conditioner |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110976505.1A CN113606761A (en) | 2021-08-24 | 2021-08-24 | Current loop communication circuit and air conditioner |
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| CN113606761A true CN113606761A (en) | 2021-11-05 |
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| CN202110976505.1A Pending CN113606761A (en) | 2021-08-24 | 2021-08-24 | Current loop communication circuit and air conditioner |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114500125A (en) * | 2022-01-21 | 2022-05-13 | 珠海格力电器股份有限公司 | Power supply and communication assembly, system and communication equipment |
| CN114777299A (en) * | 2022-03-31 | 2022-07-22 | 安徽中家智康科技有限公司 | One-to-two communication system and method for air conditioner outdoor unit |
-
2021
- 2021-08-24 CN CN202110976505.1A patent/CN113606761A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114500125A (en) * | 2022-01-21 | 2022-05-13 | 珠海格力电器股份有限公司 | Power supply and communication assembly, system and communication equipment |
| CN114500125B (en) * | 2022-01-21 | 2022-12-16 | 珠海格力电器股份有限公司 | Power supply and communication assembly, system and communication equipment |
| CN114777299A (en) * | 2022-03-31 | 2022-07-22 | 安徽中家智康科技有限公司 | One-to-two communication system and method for air conditioner outdoor unit |
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