Outdoor unit and air conditioner

Abstract

The application discloses an outdoor unit and an air conditioner, wherein the outdoor unit comprises: a rectifier circuit receiving an alternating current power supply and used for outputting a rectified voltage; a PFC circuit connected to an output end of the rectifier circuit and used for outputting a bus voltage; a thin film capacitor used for ensuring stability of the bus voltage; a driving unit receiving the bus voltage and used for driving a load of the frequency converter circuit; an isolation transformer comprising a primary side and a secondary side, the primary side receiving an alternating current power supply at a front end of the rectifier circuit, and a transformation ratio of the primary side and the secondary side is greater than 1; and a power conversion unit having an input end connected to the secondary side and used for converting the alternating current power supply of the secondary side into a direct current power supply, the direct current power supply providing a required voltage for a chip on the outdoor side. The application can reduce an interference voltage of an outdoor substrate to ground and improve outdoor communication quality when a thin film capacitor is used on a main loop of the outdoor unit.

Description

Technical Field

[0001] This invention relates to the field of air conditioning communication technology, and more particularly to an outdoor unit and an air conditioner. Background Technology

[0002] Currently, with the continuous improvement of modern science and technology, air conditioners have become widely used in people's daily lives. The control circuit of the air conditioner compressor generally uses large electrolytic capacitors to stabilize the bus voltage. However, large electrolytic capacitors are large in size and have a limited lifespan, which greatly limits the miniaturization and service life of the electronic control system. If small capacitors are used, the corresponding compressor cannot meet the requirements of electronic control due to limitations, and the system cannot operate stably and reliably.

[0003] Some air conditioning systems use an electrolysis-free solution (see...) Figure 2 This involves replacing the electrolytic capacitors used for energy storage in the frequency converter with film capacitors to avoid the problems of short lifespan, large size, and high temperature of electrolytic capacitors, while also achieving certain economic benefits.

[0004] Outdoor machines without electrolysis solutions will adopt Figure 3 The power supply is designed based on the architecture, with the auxiliary power supply directly drawn from the DC bus, outputting DC power through a flyback switching power supply, and then converting the voltage to provide the required DC 5V power to the outdoor side chip (e.g., outdoor side main control chip, communication chip).

[0005] However, after using small-capacity film capacitors instead of large-capacity electrolytic capacitors, there will be abundant harmonic components on the DC bus, which will affect the quality of indoor and outdoor Homebus communication. Summary of the Invention

[0006] In response to the problems pointed out in the background art, some embodiments of this application provide an outdoor unit that directly draws power from AC power and supplies power to the outdoor side chip after voltage conversion through an isolation transformer and a power conversion unit. This avoids the influence of high-frequency harmonics on the DC bus on the outdoor side chip, and at the same time, the isolation transformer increases the isolation between the primary and secondary sides, reduces the interference voltage of the outdoor substrate to ground, and improves the communication quality of the outdoor unit.

[0007] To achieve the above-mentioned objectives, the present invention employs the following technical solution: Some embodiments of this application relate to an outdoor unit, including: The frequency converter circuit includes: A rectifier circuit receives AC power and outputs rectified voltage. The PFC circuit is connected to the output terminal of the rectifier circuit and outputs the bus voltage. Thin-film capacitors are used to ensure the stability of the bus voltage; A drive unit that receives the bus voltage and is used to drive the load of the inverter circuit; An isolation transformer includes a primary side and a secondary side, wherein the primary side receives AC power from the front end of the rectifier circuit, and the turns ratio of the primary side and the secondary side is greater than 1. A power conversion unit, whose input terminal is connected to the secondary side, is used to convert the AC power supply on the secondary side into DC power supply, which provides the required voltage to the outdoor side chip. The outdoor-side chip includes an outdoor-side main control chip and an outdoor-side communication chip.

[0008] This technical solution has the following beneficial effects or advantages: The primary side of the isolation transformer draws power directly from the AC power supply, avoiding the impact of high-frequency harmonics from the DC bus on the outdoor chips. Furthermore, due to the increased primary-secondary isolation, even if there is interference in the AC power supply, it will not affect the voltage output from the secondary side of the isolation transformer, ensuring the reliability of the power supplied to the outdoor chips.

[0009] Furthermore, the turns ratio of the primary and secondary sides of the isolation transformer is greater than 1, which is a step-down transformer. The distributed capacitance of the secondary side to ground is greater than the distributed capacitance between the primary and secondary sides, which reduces the voltage to ground of the outdoor base plate and effectively improves the communication quality.

[0010] In some embodiments of this application, the power conversion unit includes: The first voltage converter receives the voltage output from the secondary side of the isolation transformer at its input terminal and outputs a first DC voltage. A second voltage converter receives the first DC voltage and converts it into a second DC voltage required by the outdoor chip, wherein the second DC voltage is less than the first DC voltage.

[0011] This technical solution has the following beneficial effects or advantages: The AC power supply on the outdoor side has a large amplitude. After being stepped down by the isolation transformer, the secondary side still outputs a low-amplitude AC voltage. Therefore, the first voltage converter needs to convert the AC power into DC power and output a first DC voltage. However, the amplitude of the first DC voltage is large, so a second voltage converter is needed to output a smaller second DC voltage required by the outdoor chip. In this way, the reliability and stability of the power supply for the outdoor chip are ensured.

[0012] In some embodiments of this application, the first voltage converter is a flyback switching power supply, the two ends of the primary winding of the flyback switching power supply are respectively connected to the two ends of the secondary side of the isolation transformer, and output the first DC voltage.

[0013] This technical solution has the following beneficial effects or advantages: When a flyback switching power supply is installed in the original outdoor unit to supply power to the outdoor side chip, the resource configuration of the original flyback switching power supply is not changed. Only an isolation transformer is added and the power is drawn from the AC power supply at the front end of the rectifier circuit. This reduces the interference voltage of the outdoor board to ground, ensures the reliability of power supply to the outdoor side chip, and effectively improves the communication quality of the outdoor unit.

[0014] In some embodiments of this application, the second voltage converter is a linear regulator used to regulate the second DC voltage it outputs.

[0015] This technical solution has the following beneficial effects or advantages: The second voltage converter uses a linear regulator, which on the one hand realizes the step-down conversion of DC voltage to DC voltage, and on the other hand provides a stable second DC voltage to the outdoor chip, ensuring a reliable and stable power supply to the outdoor chip.

[0016] In some embodiments of this application, the power conversion unit is an AC-DC buck converter.

[0017] This technical solution has the following beneficial effects or advantages: An AC-DC step-down converter is used as the power conversion unit. A single device can convert the AC voltage on the secondary side of the isolation transformer to the DC voltage required by the outdoor chip, which is beneficial for the miniaturization design of the outdoor substrate.

[0018] AC-DC step-down converters can be selected as isolated types, forming double isolation together with the front-end isolation transformer, ensuring the reliability of power supply to outdoor chips.

[0019] A non-isolated AC-DC step-down converter can also be selected because the AC-DC step-down converter has already selected an isolation transformer at the front end for primary and secondary isolation. Selecting a non-isolated AC-DC step-down converter can reduce cost investment.

[0020] In some embodiments of this application, the first voltage converter is an AC-DC step-down converter, which receives the voltage output from the secondary side of the isolation transformer at its input terminal and outputs the first DC voltage.

[0021] This technical solution has the following beneficial effects or advantages: To improve the stability and reliability of power supply to the outdoor chip, the power conversion unit uses a two-stage voltage conversion. First, the first voltage converter, selected as an AC-DC step-down converter, is used to convert the AC power to the first DC voltage. Then, the second voltage converter is used to convert the first DC voltage to the second DC voltage.

[0022] AC-DC step-down converters can be selected as isolated types, forming double isolation together with the front-end isolation transformer, ensuring the reliability of power supply to outdoor chips.

[0023] A non-isolated AC-DC step-down converter can also be selected because the AC-DC step-down converter has already selected an isolation transformer at the front end for primary and secondary isolation. Selecting a non-isolated AC-DC step-down converter can reduce cost investment.

[0024] In some embodiments of this application, the second voltage converter is a linear regulator used to regulate the second DC voltage it outputs.

[0025] This technical solution has the following beneficial effects or advantages: The second voltage converter uses a linear regulator, which on the one hand realizes the step-down conversion of DC voltage to DC voltage, and on the other hand provides a stable second DC voltage to the outdoor chip, ensuring a reliable and stable power supply to the outdoor chip.

[0026] In some embodiments of this application, the AC-DC buck converter is selected from non-isolated AC-DC power buck chips.

[0027] This technical solution has the following beneficial effects or advantages: Since the AC-DC step-down converter has already selected an isolation transformer for primary and secondary isolation at the front end, a non-isolated AC-DC step-down converter is selected to reduce cost investment.

[0028] In some embodiments of this application, the PFC circuit includes: An inductor is connected to one end of the positive terminal of the input power supply of the PFC circuit, and the other end of the inductor is divided into a first path and a second path. The first path is connected to the collector of the switching transistor; A diode, the second path is connected to the anode of the diode, the cathode of the diode is the output terminal of the PFC circuit, one plate of the film capacitor is connected to the cathode of the diode and the other plate is connected to the common connection position of the emitter of the switching transistor and the negative terminal of the input power supply of the PFC circuit.

[0029] This technical solution has the following beneficial effects or advantages: The PFC circuit, in conjunction with the film capacitor, achieves stable bus voltage.

[0030] Some embodiments of this application also relate to an air conditioner, comprising: Indoor unit, used to regulate indoor air; The outdoor unit, which is communicatively connected to the indoor unit via a Homebus bus, comprises: The frequency converter circuit includes: A rectifier circuit receives AC power and outputs rectified voltage. The PFC circuit is connected to the output terminal of the rectifier circuit and outputs the bus voltage. Thin-film capacitors are used to ensure the stability of the bus voltage; A drive unit that receives the bus voltage and is used to drive the load of the inverter circuit; An isolation transformer includes a primary side and a secondary side, wherein the primary side receives AC power from the front end of the rectifier circuit, and the turns ratio of the primary side and the secondary side is greater than 1. A power conversion unit, whose input terminal is connected to the secondary side, is used to convert the AC power supply on the secondary side into DC power supply, which provides the required voltage to the outdoor side chip. The outdoor-side chip includes an outdoor-side main control chip and an outdoor-side communication chip.

[0031] This technical solution has the following beneficial effects or advantages: In the outdoor unit, the primary side of the isolation transformer draws power directly from the AC power supply at the front end of the rectifier circuit, avoiding the impact of high-frequency harmonics from the DC bus on the power supply to the outdoor chip. Furthermore, due to the increased isolation provided by the isolation transformer, even if there is interference in the AC power supply, it will not affect the voltage output from the secondary side of the isolation transformer, ensuring the reliability of the power supply provided to the outdoor chip.

[0032] Furthermore, the turns ratio of the primary and secondary sides of the isolation transformer is greater than 1, making it a step-down transformer. The distributed capacitance to ground on the secondary side is greater than the distributed capacitance between the primary and secondary sides, which reduces the voltage to ground on the outdoor board, effectively improves the communication quality on the Homebus bus, and enables reliable communication between the indoor and outdoor units in the air conditioner.

[0033] Other features and advantages of the present invention will become clearer after reading the detailed embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is the main circuit for the outdoor unit, which has an electrolytic capacitor. Figure 2 For the outdoor unit main circuit with film capacitors; Figure 3 Power supply method for outdoor units with film capacitors; Figure 4 A simplified diagram showing the connection between the outdoor main control chip and the outdoor communication chip on the outdoor unit's circuit board. Figure 5 Common-mode interference circuit of flyback switching power supply in outdoor unit power supply method with film capacitor; Figure 6 A simplified diagram showing the effect of the Y capacitor on the secondary side; Figure 7 The waveforms of the communication signal V output by the outdoor communication chip, the communication signal VI received by the outdoor main control chip, and the bus signal IV are shown when the Y capacitor is set. Figure 8 A simplified diagram showing the impact on the secondary side without a Y capacitor; Figure 9 The waveforms of the communication signal V output by the outdoor communication chip, the communication signal VI received by the outdoor main control chip, and the bus signal IV are shown when the Y capacitor is not set. Figure 10 This is a schematic block diagram of the power supply method for the outdoor unit according to this application; Figure 11 The schematic diagram of the power conversion unit in the outdoor unit according to this application is shown. Figure 12 The principle of the power supply method for the outdoor unit proposed in this application. Figure 1 ; Figure 13 To Figure 12 Simplified diagram; Figure 14 For use Figure 12 The waveforms of the communication signal V output by the outdoor communication chip, the communication signal VI received by the outdoor main control chip, and the bus signal IV are shown after the power supply method is displayed. Figure 15 The principle of the power supply method for the outdoor unit proposed in this application. Figure 2 ; Figure 16 To Figure 15 Simplified diagram; Figure 17 This is a schematic diagram illustrating the communication between the indoor and outdoor units of an air conditioner according to this application; Figure label: 100. Outdoor unit; 110. Inverter circuit; 111. Rectifier circuit; 112. PFC circuit; 113. IPM; 114. Charging circuit; 120. Isolation transformer; 130. Power conversion unit; 131. First voltage converter; 131A. Flyback switching power supply; 132. Second voltage converter; 132A. LDO; 140. Outdoor side chip; 141. Outdoor side main control chip; 142. Outdoor side communication chip; 150. Demodulation circuit; 160. Modulation circuit; 170. Bus drive circuit; 181. Receiver side AC coupling circuit; 182. Transmitter side AC coupling circuit; 200. Indoor unit. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0038] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0039] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0040] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0041] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0042] Air conditioners execute a refrigeration cycle using a compressor, condenser, expansion valve, and evaporator. The refrigeration cycle involves a series of processes, including compression, condensation, expansion, and evaporation, to cool or heat an indoor space.

[0043] Low-temperature, low-pressure refrigerant enters the compressor, which compresses it into a high-temperature, high-pressure refrigerant gas and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and the heat is released to the surrounding environment through the condensation process.

[0044] The expansion valve expands the high-temperature, high-pressure liquid refrigerant that condenses in the condenser into a low-pressure liquid refrigerant. The evaporator evaporates the expanded refrigerant in the expansion valve and returns the low-temperature, low-pressure refrigerant gas to the compressor. The evaporator achieves its cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled. Throughout the cycle, the air conditioner regulates the temperature of the indoor space.

[0045] The outdoor unit of an air conditioner refers to the part of the refrigeration cycle that includes the compressor and the outdoor heat exchanger. The indoor unit of an air conditioner includes the indoor heat exchanger, and an expansion valve can be provided in either the indoor or outdoor unit.

[0046] The indoor and outdoor heat exchangers function as either condensers or evaporators. When the indoor heat exchanger is used as a condenser, the air conditioner functions as a heater in heating mode; when the indoor heat exchanger is used as an evaporator, the air conditioner functions as a cooler in cooling mode.

[0047] The outdoor unit of an air conditioner is usually referred to as outdoor unit 100, and the indoor unit of an air conditioner is usually referred to as indoor unit 200.

[0048] Figure 1 The outdoor unit main circuit with electrolytic capacitors E1 / E2 is shown. Figure 2 The outdoor unit main circuit without electrolytic capacitors is shown.

[0049] Figure 1 The main circuit of the outdoor unit includes a frequency converter circuit 110, which includes a rectifier circuit 111, a charging circuit 114, a PFC circuit 112, electrolytic capacitors E1 / E2 (and a balancing resistor (not shown) connected in parallel with them) and a drive unit.

[0050] The drive unit is used to drive the load of the inverter circuit 110 and includes a driver (not shown) and an IPM (Intelligent Power Module) 113. The driver is used to drive each switching transistor in the IPM 113, and the IPM 113 is used to receive the bus voltage output by the PFC circuit 112 to drive the load.

[0051] The purpose of adding a balancing resistor is to prevent the electrolytic capacitors E1 / E2 from being damaged due to voltage imbalance across them.

[0052] Figure 2 The outdoor unit main circuit shown in the figure is relative to Figure 1 The charging circuit 114 and the balancing resistors connected in parallel with the electrolytic capacitors E1 / E2 are omitted, and the electrolytic capacitors E1 / E2 are replaced by a thin film capacitor C. The inverter circuit 110 still includes a rectifier circuit 111, a PFC circuit 112 and a drive unit.

[0053] The drive unit is used to drive the load of the inverter circuit 110 and includes a driver and an IPM 113. The driver is used to drive each switch in the IPM 113, and the IPM 113 is used to receive the bus voltage output by the PFC circuit 112 to drive the load.

[0054] In some embodiments of this application, the power supply method of the outdoor unit 100 under an electrolysis-free scheme is mainly considered. Therefore, with Figure 2 For example, the rectifier circuit 111, the PFC circuit 112, and the film capacitor C can form the power supply device for the outdoor unit 100.

[0055] See Figure 1 and Figure 2 At the very front, the input terminal of the rectifier circuit 111 is connected to a (single-phase or three-phase) AC power supply. The rectifier circuit 111 is used to rectify the AC power supplied by the AC power supply to obtain rectified pulsating waves.

[0056] The rectifier circuit 111 is a single-phase bridge rectifier bridge composed of four diodes, or a three-phase bridge rectifier bridge composed of six diodes.

[0057] See also Figure 1 and Figure 2 The PFC circuit 112 is connected between the output terminal of the rectifier circuit 111 and the thin film capacitor C. The PFC circuit 112 is used to perform power factor correction on the power supply.

[0058] The film capacitor C is connected in parallel with the load, which can refer to a compressor or an outdoor fan.

[0059] That is, after the AC power is rectified by the rectifier circuit 111, it passes through the PFC circuit 112 and then drives the IPM 113 to supply power to the load.

[0060] See also Figure 1 and Figure 2 The power output from the rectifier circuit 111 serves as the input power supply for the PFC circuit 112, and has a positive input power supply terminal and a negative input power supply terminal.

[0061] The PFC circuit 112 includes an inductor L, a switching transistor Q1, and a diode D1.

[0062] The positive terminal of the input power supply of PFC circuit 112 is connected to one end of inductor L, and the other end of inductor L is divided into two paths: the first path and the second path.

[0063] The first path is connected to the collector of the switching transistor Q1, and the second path is connected to the anode of the diode D1.

[0064] The cathode of diode D1 is the output terminal of PFC circuit 112. One end of film capacitor C is connected to the cathode of diode D1, and the other end of film capacitor C is connected to the emitter of switching transistor Q1, the negative terminal of the input power supply of PFC circuit 112, and ground.

[0065] The rectifier circuit 111 and the thin film capacitor C are both used in conjunction with the PFC circuit 112.

[0066] The PFC circuit 112 can correct the power factor of the power supply and boost the rectified pulsating wave to provide a stable DC bus voltage Vdc to the film capacitor C.

[0067] The DC bus voltage Vdc output by PFC circuit 112 is supplied to IPM 113.

[0068] In some embodiments of this application, see Figure 3 In the existing electrolysis-free outdoor unit 100, when powering the outdoor unit 100, the main power supply circuit supplies power to the drive motor (e.g., compressor, outdoor fan, etc.), and the auxiliary power supply circuit supplies power to the outdoor side chip 140 (e.g., outdoor side main control chip 141, outdoor side communication chip 142). The auxiliary power supply circuit is equipped with a flyback switching power supply 131A that draws power directly from the bus.

[0069] During the communication process between indoor unit 200 and outdoor unit 100, it was discovered that... Figure 3 Under the outdoor unit power supply method shown, communication interference will occur on the communication bus, affecting communication quality. The specific reasons will be explained below.

[0070] In some embodiments of this application, the communication principle between the outdoor unit 100 and the indoor unit 200 will be described first.

[0071] The indoor unit 200 and the outdoor unit 100 are connected to the Homebus bus for communication. Communication signals can be sent from the indoor unit 200 to the outdoor unit 100, or from the outdoor unit 100 to the indoor unit 200.

[0072] In some embodiments of this application, the focus is on the impact of power supply on the outdoor unit side on the outdoor communication quality; therefore, see [link to relevant documentation]. Figures 4 to 16 The description focuses on the communication on the outdoor unit side.

[0073] See Figure 4 The outdoor unit 100 includes an outdoor main control chip 141 and an outdoor communication chip 142.

[0074] In some embodiments of this application, the outdoor communication chip 142 typically uses the MM1192 communication chip, which receives signals that have undergone Alternate Mark Inversion (AMI) (hereinafter referred to as AMI signals).

[0075] The outdoor communication chip 142 has a Homebus bus interface for connecting to the Homebus bus.

[0076] The Homebus includes a first differential bus (i.e., Homebus-A) and a second differential bus (i.e., Homebus-B), on which the bus AMI signal is transmitted.

[0077] In some embodiments of this application, in order to ensure the transmission of AMI signals, a corresponding peripheral circuit is also provided for the outdoor communication chip 142.

[0078] The peripheral circuit described above includes: a signal coupling circuit, a bus drive circuit 170, a demodulation circuit 150, and a modulation circuit 160.

[0079] The signal coupling circuit is used to send and receive communication commands for the outdoor communication chip 142, and includes a receiving-side AC coupling circuit 181 and a sending-side AC coupling circuit 182.

[0080] The receiving-side AC coupling circuit 181 is used to receive communication signals sent from the indoor unit 200 on the Homebus bus and send them to the receiving end of the outdoor communication chip 142 of the outdoor unit 100.

[0081] The receiving-side AC coupling circuit 181 is implemented by selecting appropriate resistors and capacitors to ensure that the signal received from the Homebus bus is filtered out from noise such as DC signals.

[0082] The transmitting-side AC coupling circuit 182 is used to receive the communication signal output by the outdoor-side communication chip 142 at the transmitting end and send it to the Homebus bus.

[0083] The AC coupling circuit 182 on the transmitting side is implemented by selecting appropriate resistors and capacitors to ensure that the signal sent to the Homebus bus is filtered out of noise such as DC signals.

[0084] Due to the technical requirements of the MM1192 communication chip, see [link / reference]. Figure 4 A bus drive circuit 170 is also connected between Homebus-A and Homebus-B of the Homebus bus to drive the signal output by the external communication chip 142 at the transmitting end of the amplifier.

[0085] When the outdoor unit 100 receives a signal, the AMI signal from the Homebus bus (i.e., the signal shown at IV) is received by the Homebus bus interface on the receiving side of the outdoor communication chip 142 and outputs the signal shown at V at its output terminal.

[0086] The signal shown at output VI is converted by demodulation circuit 150 and received at the receiver RXD of outdoor main control chip 141.

[0087] When the outdoor unit 100 sends a signal, after processing by the outdoor main control chip 141, the signal shown at point I is output at the signal transmission terminal TXD of the outdoor main control chip 141 and sent to the modulation circuit 160.

[0088] The signal shown at output III after conversion by modulation circuit 160 is input to the input terminal of outdoor communication chip 142.

[0089] In some embodiments of this application, based on the parasitic capacitance circuit of the flyback switching power supply 131A, Figure 5 The common-mode interference circuit of flyback switching power supply 131A is shown. Cpc is the distributed capacitance of the primary winding of flyback switching power supply 131A to the magnetic core, Cps is the distributed capacitance of the primary winding of flyback switching power supply 131A to the secondary winding, Ccg is the distributed capacitance of the magnetic core of flyback switching power supply 131A to ground, and Csg is the distributed capacitance of the secondary winding of flyback switching power supply 131A to ground. Among them, the dominant capacitance is Cps.

[0090] In the flyback switching power supply 131A, the switching transistor can be controlled to be cut off or turned on, for example, by a square wave output by the power supply chip, and the flyback switching power supply 131A is used to convert, for example, AC 220V to DC 15V.

[0091] See Figure 6 The power supply chip, switching transistor, and flyback switching power supply 131A can be considered as a single interference source, and the interference voltage to ground generated by the interference source can be analyzed.

[0092] A Y capacitor is a type of safety capacitor. (See also: [link to relevant documentation]) Figure 5 When the Y capacitor (Cy) is used in the flyback switching power supply 131A, it is connected in series between the high voltage ground and the low voltage ground to provide a loop for the common-mode current of the secondary to the primary, reducing the impact of the common-mode current on the output and playing a role in suppressing common-mode interference. It can effectively reduce the impact of electromagnetic interference on the circuit.

[0093] See Figures 6 to 9 The interference of the interference voltage generated by the interference source to ground on the communication of the outdoor unit is explained from two aspects: with and without Y capacitor Cy.

[0094] In some embodiments of this application, see Figure 6 This shows a simplified diagram of the effect of the Y capacitor Cy on the secondary side.

[0095] Since the distributed capacitance of the flyback switching power supply 131A, as mentioned above, is generally less than 100pF, while the value of the Y capacitor Cy is generally above 100pF, therefore, considering C... sg When connected in parallel with Cy, the distributed capacitance is negligible.

[0096] Assuming the interference voltage generated by the interference source to ground is Vnoise, then the impedance to ground at point B (equivalent to the secondary ground of the 131A flyback switching power supply, specifically the secondary ground on the outdoor substrate during testing) is Xb = 1 / (2πfC). sg The impedance of capacitor Y is Xy = 1 / (2πfCy), and the voltage at point B is VB = Vnoise*Xb / (Xb + Xy).

[0097] When the air conditioner is running, because the resistance of the Y capacitor is relatively large and the impedance is relatively small, the voltage to ground on the outdoor circuit board will be relatively high. The voltage at point B to the outdoor unit's 100-inch sheet metal will reach about 100V.

[0098] When the outdoor unit 100 operates using the electrolytic-free solution with the Y capacitor as described above, please refer to... Figure 7 Communication failures will occur, interference will appear in the middle level of the bus waveform IV, and it can be clearly seen from the waveform VI received by the outdoor main control chip 141 that the part that should be high level (between a and b) in the receiving part of the outdoor main control chip 141 has become alternating high and low levels. This situation will directly lead to communication failure.

[0099] In some embodiments of this application, see Figure 8 This diagram shows a simplified representation of the effect on the secondary side without the Y capacitor Cy.

[0100] Without the Y capacitor, the distributed capacitance C between the primary and secondary sides of the flyback switching power supply 131A is... ps It plays a dominant role, therefore, C ps Take that into consideration.

[0101] Assuming the interference voltage generated by the interference source to ground is Vnoise, then the impedance of point B to ground is Xb = 1 / (2πfC). sg ), C ps The impedance of the capacitor itself is Xc = 1 / (2πfC). ps The voltage at point B is VB = Vnoise * Xb / (Xb + Xc).

[0102] When the air conditioner is running, C ps The capacitor plays a major role, with most of the voltage applied to the flyback switching power supply 131A. When testing point B, the voltage across the outdoor unit's 100mm sheet metal reaches approximately 30V.

[0103] See Figure 9 In this case, although no communication failure occurred, the bus waveform IV still showed interference, according to the bus waveform quality analysis.

[0104] In some embodiments of this application, in order to remove interference on the bus, see [link to relevant documentation]. Figure 10 An isolation transformer 120 is installed on the auxiliary power supply circuit. This isolation transformer 120 draws power from the AC power supply (e.g., AC 400V) at the front end of the rectifier circuit 111, and does not draw power from the DC bus with high harmonic content. Therefore, the high-frequency harmonics on the DC bus are avoided from affecting the power supply of the downstream outdoor chip 140, and the communication quality is effectively improved.

[0105] Furthermore, the isolation transformer 120 can increase the isolation between the primary and secondary sides, preventing front-end interference from interfering with the back-end outdoor chip 140.

[0106] In some embodiments of this application, see Figure 10 The outdoor unit 100 also includes a power conversion unit 130.

[0107] The primary side of the isolation transformer 120 is connected to the AC power supply at the front end of the rectifier circuit 111, and the secondary side is connected to the input terminal of the power conversion unit 130. The power conversion unit 130 outputs DC power, which provides the required voltage to the outdoor chip 140.

[0108] In some embodiments of this application, the primary-secondary turns ratio of the isolation transformer 120 is greater than 1, that is, the isolation transformer 120 is a step-down transformer.

[0109] In some embodiments of this application, the primary side of the isolation transformer 120 receives an AC 400V voltage, which can be stepped down to AC 220V (this type of isolation transformer 120 is referred to as T1); the power conversion unit 130 is an AC to DC step-down converter.

[0110] In some embodiments of this application, the outdoor main control chip 141 and the outdoor communication chip 142 require a DC +5V voltage. Therefore, the power conversion unit 130 can be selected as a step-down converter that converts AC 220V to DC 5V.

[0111] This 220V AC to 5V DC step-down converter can be either isolated or non-isolated.

[0112] Since the power conversion unit 130 already has an isolation transformer 120 at the front end for isolation, in order to reduce costs, the AC 220V to DC 5V step-down converter can be selected as a non-isolated AC-DC power chip step-down circuit. It can be built using inductors, varistors, rectifier bridges, capacitors, XD308H power chips and other components to form a non-isolated power supply with an output of 5V / 0.5A.

[0113] In some embodiments of this application, see Figure 11 In order to provide a stable and reliable power supply to the outdoor chip 140, the power conversion unit 130 includes a first voltage converter 131 and a second voltage converter 132.

[0114] The input terminal of the first voltage converter 131 receives the voltage output from the secondary side of the isolation transformer 120 and outputs a first DC voltage.

[0115] In some embodiments of this application, the first voltage converter 120 is an AC to DC buck converter.

[0116] In some embodiments of this application, the first voltage converter 120 may be selected as a step-down converter that converts AC 220V to DC 12V / 15V.

[0117] This 220V AC to 12 / 15V DC step-down converter can be either isolated or non-isolated.

[0118] Since the front end already has an isolation transformer 120 for isolation, in order to reduce costs, this AC 220V to DC 12 / 15V step-down converter can be a non-isolated AC-DC power chip step-down circuit. It can be built using inductors, varistors, rectifier bridges, capacitors, XD308H power chips and other components to form a non-isolated power supply with an output of, for example, 12V / 0.5A.

[0119] In some embodiments of this application, the second voltage converter 132 is a DC-DC to DC-DC buck converter.

[0120] In some embodiments of this application, see Figure 12 ,against Figure 3 The circuit already includes an auxiliary power supply circuit with a flyback switching power supply 131A and a linear regulator LDO 132A (low-dropout regulator). Utilizing the existing configuration of the flyback switching power supply 131A and the linear regulator LDO 132A, the flyback switching power supply 131A is used as the first voltage converter 131, and the linear regulator LDO 132A is used as the second voltage converter 132.

[0121] Still referencing Figure 12 The primary and secondary sides of the isolation transformer 120 are connected to the AC power supply at the front end of the rectifier circuit 111, and the secondary side is connected to the input terminal of the flyback switching power supply 131A. The output terminal of the flyback switching power supply 131A is connected to the input terminal of the linear regulator LDO 132A.

[0122] In some embodiments of this application, when the primary side of the isolation transformer 120 receives an AC 400V voltage and steps it down to AC 220V, the flyback switching power supply 131A can convert the AC 220V into a first DC voltage, which can be DC 15V.

[0123] The linear regulator LDO 132A receives a first DC voltage and converts it into a second DC voltage, which can be 5V DC.

[0124] As described above, the use of a two-layer conversion between a first voltage converter 131 and a second voltage converter 132 ensures reliable power supply to the outdoor chip 140. At the same time, the linear regulator LDO 132A of the second voltage converter 132 can stably output a second DC voltage to provide a stable voltage for the outdoor chip 140.

[0125] In some embodiments of this application, the portions of the auxiliary power supply circuit that affect the voltage required by the outdoor chip 140 are collectively referred to as interference sources. Therefore, when using... Figure 12 When the power supply method is shown, it can be simplified to Figure 13 Conduct theoretical analysis.

[0126] When the isolation transformer 120 receives 400V AC voltage on its primary side and outputs 220V AC voltage on its secondary side, there is also a distributed capacitance C' between the primary and secondary sides of the isolation transformer 120. ps The distributed capacitance of the secondary winding to ground is C. line After actual testing, C line Approximately 10 times C' ps .

[0127] Assuming the interference voltage generated by the interference source to ground is Vnoise, then the impedance of point B to ground is Xb = 1 / (2πfC). sg ), C ps The impedance of the capacitor itself is Xc = 1 / (2πfC). ps Therefore, the voltage at point B, VB = Vnoise * (Xb / (Xb + Xc)) * (1 / 11), is 1 / 11 of the original voltage. That is, without the Y capacitor Cy, the voltage at point B to ground is less than 3V, and with the Y capacitor Cy, the voltage at point B to ground is less than 10V. The interference voltage generated by the interference source to ground is significantly reduced compared to before.

[0128] See Figure 14 It shows the bus waveform IV, the waveform VI received by the receiver RXD of the outdoor main control chip 141, and the waveform V output by the outdoor communication chip 142.

[0129] Waveform analysis shows that interference is virtually nonexistent on the bus, and long-term verification confirms its effectiveness.

[0130] In some embodiments of this application, the flyback switching power supply 131A can be replaced for cost considerations. In this case, the conversion voltage of the first voltage converter 131 is different from that of the flyback switching power supply 131A.

[0131] In some embodiments of this application, the type of the first voltage converter 131 can be selected based on the primary-secondary turns ratio of the isolation transformer 120 at the front end of the first voltage converter 131.

[0132] When the primary side of the isolation transformer 120 receives AC 400V voltage and is stepped down to AC 22V (the isolation transformer 120 in this case is referred to as T2), the first voltage converter 131 can select a step-down converter that converts AC 22V to DC 12V / 15V.

[0133] This 22V AC to 12 / 15V DC step-down converter can be either isolated or non-isolated.

[0134] Since the front end already has an isolation transformer 120 for isolation, in order to reduce costs, this AC 22V to DC 12 / 15V step-down converter can be selected as a non-isolated AC-DC power chip step-down circuit.

[0135] The second voltage converter 132 can be a linear regulator LDO 132A to provide a stable voltage to the outdoor-side chip 140.

[0136] In Adoption Figure 15 When the power supply method is shown, it can be simplified to Figure 16 Conduct theoretical analysis.

[0137] When the isolation transformer 120 receives 400V AC voltage on its primary side and outputs 22V AC voltage on its secondary side, there is a distributed capacitance C' between the primary and secondary sides of the isolation transformer 120. ps The distributed capacitance of the secondary winding to ground is C. line After actual testing, C line Approximately 100 times C' ps .

[0138] Since the flyback switching power supply 131A has been removed, C no longer exists. ps and C sg .

[0139] Assuming the interference voltage generated by the interference source to ground is Vnoise, then the voltage at point B, VB = Vnoise**(1 / 101), is lower than before, thus improving communication quality.

[0140] In some embodiments of this application, the air conditioner includes an indoor unit 200 and an outdoor unit 100, and the indoor unit 200 and the outdoor unit 100 are communicatively connected to a Homebus bus.

[0141] See Figure 17It shows a simplified block diagram of communication between an indoor unit 200 and an outdoor unit 100.

[0142] The outdoor unit 100 includes an outdoor main control chip 141 and an outdoor communication chip 142.

[0143] The main power supply circuit of the outdoor unit 100 includes a frequency converter circuit 110, which includes a rectifier circuit 111, a PFC circuit 112, a film capacitor C, and a drive unit. The auxiliary power supply circuit of the outdoor unit 100 includes an isolation transformer 120 and a power conversion unit 130. The primary side of the isolation transformer 120 receives the AC power from the front end of the rectifier circuit 111. The power conversion unit 130 is used to convert the AC voltage on the secondary side of the isolation transformer 120 into the voltage required by the outdoor main control chip 141 and the outdoor communication chip 142.

[0144] Because an isolation transformer 120 that draws power directly from the AC power supply is added to the auxiliary power supply circuit, power is avoided from the DC bus with abundant harmonic components, reducing interference to the power supply to the outdoor chip 140 at the back end. At the same time, because the isolation transformer 120 increases the primary-secondary isolation, even if there is interference in the AC power supply, it will not affect the voltage output on the secondary side of the isolation transformer 120, ensuring the reliability of the power supply to the outdoor chip 140.

[0145] Furthermore, the turns ratio of the primary and secondary sides of the isolation transformer 120 is greater than 1, which is a step-down transformer. The distributed capacitance of the secondary side to ground is greater than the distributed capacitance between the primary and secondary sides, which reduces the voltage to ground of the outdoor substrate and effectively improves the communication quality.

[0146] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0147] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An outdoor unit, characterized in that, include: The frequency converter circuit includes: A rectifier circuit receives AC power and outputs rectified voltage. The PFC circuit is connected to the output terminal of the rectifier circuit and outputs the bus voltage. Thin-film capacitors are used to ensure the stability of the bus voltage; A drive unit that receives the bus voltage and is used to drive the load of the inverter circuit; An isolation transformer includes a primary side and a secondary side, wherein the primary side receives AC power from the front end of the rectifier circuit, and the turns ratio of the primary side and the secondary side is greater than 1. A power conversion unit, whose input terminal is connected to the secondary side, is used to convert the AC power supply on the secondary side into DC power supply, which provides the required voltage to the outdoor side chip. The outdoor-side chip includes an outdoor-side main control chip and an outdoor-side communication chip.

2. The outdoor unit according to claim 1, characterized in that, The power conversion unit includes: The first voltage converter receives the voltage output from the secondary side of the isolation transformer at its input terminal and outputs a first DC voltage. A second voltage converter receives the first DC voltage and converts it into a second DC voltage required by the outdoor-side chip. Wherein, the second DC voltage is less than the first DC voltage.

3. The outdoor unit according to claim 2, characterized in that, The first voltage converter is a flyback switching power supply. The two ends of the primary winding of the flyback switching power supply are respectively connected to the two ends of the secondary side of the isolation transformer, and output the first DC voltage.

4. The outdoor unit according to claim 3, characterized in that, The second voltage converter is a linear regulator used to regulate the second DC voltage it outputs.

5. The outdoor unit according to claim 1, characterized in that, The power conversion unit is an AC-DC step-down converter.

6. The outdoor unit according to claim 2, characterized in that, The first voltage converter is an AC-DC step-down converter, which receives the voltage output from the secondary side of the isolation transformer at its input terminal and outputs a first DC voltage.

7. The outdoor unit according to claim 6, characterized in that, The second voltage converter is a linear regulator used to regulate the second DC voltage it outputs.

8. The outdoor unit according to claim 6, characterized in that, The AC-DC buck converter uses a non-isolated AC-DC power buck chip.

9. The outdoor unit according to claim 1, characterized in that, The PFC circuit includes: An inductor is connected to one end of the positive terminal of the input power supply of the PFC circuit, and the other end of the inductor is divided into a first path and a second path. The first path is connected to the collector of the switching transistor; A diode, the second path is connected to the anode of the diode, the cathode of the diode is the output terminal of the PFC circuit, one plate of the film capacitor is connected to the cathode of the diode and the other plate is connected to the common connection position of the emitter of the switching transistor and the negative terminal of the input power supply of the PFC circuit.

10. An air conditioner, characterized in that, include: Indoor unit, used to regulate indoor air; The outdoor unit, which is communicatively connected to the indoor unit via a Homebus bus, comprises: The frequency converter circuit includes: A rectifier circuit receives AC power and outputs rectified voltage. The PFC circuit is connected to the output terminal of the rectifier circuit and outputs the bus voltage. Thin-film capacitors are used to ensure the stability of the bus voltage; A drive unit that receives the bus voltage and is used to drive the load of the inverter circuit; An isolation transformer includes a primary side and a secondary side, wherein the primary side receives AC power from the front end of the rectifier circuit, and the turns ratio of the primary side and the secondary side is greater than 1. A power conversion unit, whose input terminal is connected to the secondary side, is used to convert the AC power supply on the secondary side into DC power supply, which provides the required voltage to the outdoor side chip. The outdoor-side chip includes an outdoor-side main control chip and an outdoor-side communication chip.

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