Fan driving circuit of air conditioner and air conditioner

Abstract

The invention discloses a fan driving circuit of an air conditioner and the air conditioner, and the circuit comprises a control module which is used for sending a driving signal for driving a fan; the driving module is used for driving the fan to operate, and the driving module comprises a first port used for receiving a driving signal; wherein the driving module is connected with a first ground, and the control module is connected with a second ground; the first ground is connected with the second ground; the first ground represents a ground terminal not isolated from the mains supply, and the second ground represents a ground terminal isolated from the mains supply; in the transmission process of the driving signal, the driving signal does not pass through the optocoupler. The hot ground (namely the first ground) and the cold ground (namely the second ground) of a traditional air conditioner are connected, so that the reference potential of the control module is the same as that of the driving module, an optocoupler on a fan driving circuit can be omitted, effective communication between the control module and the fan is kept, and the size of a PCB (printed circuit board) in the air conditioner is reduced.

Description

Technical Field

[0001] The present application relates to air conditioning technology in the field of electronic technology, and in particular to a fan drive circuit of an air conditioner and an air conditioner. Background Art

[0002] In the related art, an optocoupler is connected to the circuit where the speed drive signal port Vsp and the speed feedback signal port Vfg on the DC fan of an existing air conditioner are located. Due to the large size of the optocoupler, the size of the PCB (Printed Circuit Board) is large, which is not conducive to the development of miniaturized electronic controls such as integrated air conditioners. Summary of the Invention

[0003] In view of this, an embodiment of the present application provides a fan drive circuit of an air conditioner and an air conditioner, aiming to reduce the PCB size of the air conditioner.

[0004] The technical solution of the embodiment of the present application is implemented as follows:

[0005] In a first aspect, an embodiment of the present application provides a fan drive circuit for an air conditioner, comprising:

[0006] A control module, used for sending a driving signal for driving the fan;

[0007] A driving module, configured to drive the fan to operate, the driving module comprising a first port, the first port being configured to receive the driving signal;

[0008] Wherein, the driving module is connected to a first ground, and the control module is connected to a second ground; the first ground is connected to the second ground; the first ground represents a ground terminal that is not isolated from the mains power, and the second ground represents a ground terminal that is isolated from the mains power;

[0009] During the transmission of the driving signal, the driving signal does not pass through the optical coupler.

[0010] In some embodiments, the circuit further includes a switching power supply, which is configured to provide at least a first power source to the first port; in the switching power supply, the branch where the port of the first power source is located includes a feedback circuit.

[0011] In some embodiments, the switching power supply includes a switching power supply chip, the feedback circuit includes a voltage stabilizing module and a first optocoupler; the voltage stabilizing module includes a second port, a third port, and a fourth port;

[0012] The voltage stabilizing module is configured to: when the voltage of the second port exceeds a first voltage threshold, conduction is performed between the third port and the fourth port, so that conduction is performed between the collector and the emitter of the first optical coupler, and the switching power supply chip receives a first signal;

[0013] The first signal is used to instruct the switching power supply chip to reduce the voltage of the first power supply.

[0014] In some embodiments, the voltage stabilization module further includes an operational amplifier and a transistor, the second port is connected to the positive input of the operational amplifier, the output of the operational amplifier is connected to the base of the transistor, the collector of the transistor is connected to the third port, and the emitter of the transistor is connected to the fourth port.

[0015] In some embodiments, the switching power supply chip includes a fifth port; the port of the first power supply is connected to the second port through a first resistor, the fifth port is connected to the collector of the first optocoupler, and the emitter of the first optocoupler is connected to the first ground.

[0016] In some embodiments, one end of the first resistor is connected to a port of the first power source, and the other end is respectively connected to the second port and a second resistor, and the second resistor is connected to the second ground.

[0017] In some embodiments, the air conditioner further comprises a touch module and / or a display module;

[0018] The switching power supply module is further configured to provide a second power supply to at least the touch control module and / or the display module;

[0019] The touch module and / or the display module is connected to a third ground, and the third ground is isolated from the first ground and the second ground.

[0020] In some embodiments, the driving module further includes a sixth port, and the sixth port is used to output a feedback signal;

[0021] The feedback signal includes the rotation speed information of the fan;

[0022] The control module is further configured to receive the feedback signal and output the driving signal based on the feedback signal.

[0023] In some embodiments, the control module is specifically configured to:

[0024] outputting a drive signal based on first speed information, wherein the first speed information includes a target speed of the fan;

[0025] receiving the feedback signal, and determining second speed information based on the feedback signal, wherein the second speed information includes an actual speed of the fan;

[0026] If it is determined based on the first speed information and the second speed information that the target speed is different from the actual speed, the duty cycle of the driving signal is adjusted until the actual speed is the same as the target speed.

[0027] In some embodiments, the bottom of the printed circuit board PCB where the control module is located is wrapped with a plastic shell made of ABS material, and the outside of the plastic shell is wrapped with fireproof sheet metal.

[0028] In a second aspect, an embodiment of the present application provides an air conditioner, comprising a fan and a fan drive circuit as described in the first aspect.

[0029] The fan drive circuit provided by the embodiment of the present application includes: a control module for sending a drive signal for driving the fan; a drive module for driving the fan to operate, the drive module including a first port, the first port being used to receive the drive signal; wherein the drive module is connected to a first ground, and the control module is connected to a second ground; the first ground is connected to the second ground; the first ground represents a ground terminal that is not isolated from the mains power, and the second ground represents a ground terminal that is isolated from the mains power; during the transmission of the drive signal, the drive signal does not pass through an optocoupler. By connecting the hot ground (i.e., the first ground) and the cold ground (i.e., the second ground) of the traditional air conditioner, the reference potential of the control module is made the same as the reference potential of the drive module, so that the drive signal sent by the control module and the signal that can be received by the fan are at the same potential reference. In this way, the solution provided by the embodiment of the present application can eliminate the optocoupler on the fan drive circuit and maintain effective communication between the control module and the fan, reducing the size of the PCB in the air conditioner, which is conducive to the development of miniaturized electronic control. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic structural diagram of a fan drive circuit provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of the circuit structure of a conventional fan drive circuit provided in an embodiment of the present application;

[0032] Figure 3 A schematic diagram of the circuit structure of a fan drive circuit provided in an embodiment of the present application;

[0033] Figure 4 A simulation diagram of the fan drive circuit provided for the application example of this application;

[0034] Figure 5 A schematic diagram of the circuit structure of a switching power supply provided for the application example of this application;

[0035] Figure 6Schematic diagram of the waveform of the Vsp port voltage connected to the +15V / 100mA power supply provided for the application example of this application

[0036] Figure 7 Schematic diagram of the simulated waveform of the Vsp port voltage connected to a +15V / 100mA power supply provided for the application example of this application;

[0037] Figure 8 A schematic diagram of the signal waveforms of port Vsp and port Vfg after removing the optical coupler provided in the application example of this application;

[0038] Figure 9 Schematic diagram of the DC fan control logic provided for the application example of this application. DETAILED DESCRIPTION

[0039] The present application will be described in further detail below with reference to the accompanying drawings and embodiments.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0041] In the related art, optocouplers are provided on the circuits where the speed drive signal port Vsp and the speed feedback signal port Vfg on the DC fan of the existing air conditioner are located. Due to the large size of the optocoupler, the size of the PCB (Printed Circuit Board) is large, which is not conducive to the development of miniaturized electronic controls such as all-in-one air conditioners.

[0042] In various embodiments of the present application, by connecting the hot ground and the cold ground of the traditional air conditioner, the reference potential of the control module is made the same as the reference potential of the drive module, so that the drive signal sent by the control module and the signal that the fan can receive are at the same potential reference. In this way, the solution provided by the embodiment of the present application can eliminate the optocoupler on the fan drive circuit and maintain effective communication between the control module and the fan, reducing the size of the PCB in the air conditioner, which is conducive to the development of miniaturized electronic control.

[0043] The embodiment of the present application provides a fan drive circuit, such as Figure 1As shown, it includes: a control module 101 and a drive module 102, the control module 101 is used to send a drive signal for driving the fan; the drive module 102 is used to drive the fan to operate, and the drive module 102 includes a first port 1021, and the first port 1021 is used to receive the drive signal; wherein, the drive module 102 is connected to a first ground, and the control module 101 is connected to a second ground; the first ground is connected to the second ground; the first ground represents a grounding end that is not isolated from the mains, and the second ground represents a grounding end that is isolated from the mains; during the transmission of the drive signal, the drive signal does not pass through the optocoupler.

[0044] In actual application, the driving signal can be a pulse width modulation (PWM) wave, and the fan speed can be increased by increasing the duty cycle of the PWM wave; the first ground can also be called a hot ground, which is not isolated from the live wire and neutral wire of the mains. In the air conditioner, the primary side of the switching power transformer is directly connected to the AC power grid and the hot ground. The potential on the hot ground wire is not equal to the real earth potential and may have a fluctuating voltage; the second ground can also be called a cold ground. The secondary side of the switching power transformer, that is, the DC low-voltage part (such as +5V, +12V) output through the transformer isolation is generally connected to the cold ground. The cold ground is electrically isolated from the high-voltage power grid. The ground wire is usually directly defined as the "0V" reference point of the air conditioner; here, the specific names of the first ground and the second ground are not limited in this embodiment of the application. The driving module can also be called a motor control module or a motor control board module. The specific name of the driving module is not limited in this embodiment of the application.

[0045] The control module may specifically include a microcontroller unit (MCU), a system on chip (SoC), a digital signal processor (DSP), or a field-programmable gate array (FPGA). The embodiments of the present application do not limit the specific device type and model of the control module.

[0046] For example, a conventional fan drive circuit such as Figure 2 As shown, it includes: fan drive module CN308, fuse FUSE2, electrolytic capacitor E521, transient suppression diode DZ510, capacitor CX501, capacitor C521, capacitor C522, capacitor C523, resistor R517, resistor R518, resistor R519, resistor R520, resistor R521, resistor R522, resistor R523, resistor R524, resistor R526, optocoupler IC504, optocoupler IC505, and transistor Q503;

[0047] Among them, the fan drive module CN308 includes port Vs, port NC, port +15V, port GND, port Vsp (i.e. the above-mentioned first port), and port Vfg; port NC is an empty port, port GND is connected to the thermal ground, port Vs is connected to the DC bus power supply P+ through the fuse FUSE2, and is connected to the thermal ground through the capacitor CX501, port +15V is connected to the +15V, 100mA power supply, port Vsp is connected to R517 and then connected to the capacitor C521, transient suppression diode DZ510, electrolytic capacitor E521, resistor R518, and finally connected to the emitter of the optocoupler IC504. The other ends of the capacitor C521, transient suppression diode DZ510, electrolytic capacitor E521, and resistor R518 are all connected to the thermal ground. The collector of the optocoupler IC504 receives the +15V voltage and 100mA power supply through the resistor R519, and the anode of the diode of the optocoupler IC504 is connected to the 5V power supply. Voltage, the cathode is connected to the collector of the transistor Q503 through the resistor R526, the emitter of the transistor Q503 is grounded, the base is connected to the resistors R23 and R524 respectively, the other end of the resistor R23 is connected to the cold ground, and the other end of the resistor R524 receives the drive signal 24T_DCFAN1-C, which is used to receive the drive signal from the control module; the port Vfg is connected to the capacitor C522 and the cathode of the diode of the optocoupler IC505 respectively, the other end of the capacitor C522 is connected to the hot ground, the anode of the diode of the optocoupler IC505 is connected to the +15V, 100mA power supply through the resistor R520, the emitter of the optocoupler IC505 is connected to the cold ground, the collector is connected to the resistors R521 and R522 respectively, the other end of the resistor R521 receives the +5V power supply voltage, the other end of the resistor R522 is connected to the capacitor C523 and sends the feedback signal 24T_DCFAN1-F, and the other end of the capacitor C523 is connected to the cold ground. Here, P+ can also be called the electric control board bus power supply, and the +15V, 100mA power supply can be called the power module drive control power supply or the motor control module drive power supply.

[0048] In actual application, when the PWM wave sent by the control module is at a high level, it turns on transistor Q503, thereby turning on the optocoupler IC504. When the optocoupler IC504 is turned on, the 15V, 100mA power supply charges the integrator circuit where the electrolytic capacitor E521 is located, raising the voltage at port Vsp. The higher the PWM wave's duty cycle, the longer it takes for electrolytic capacitor E521 to charge, and the higher the voltage at port Vsp, thereby controlling the fan speed. The driver module's Vfg port outputs a PWM waveform feedback signal, which, when low, turns on the optocoupler IC505. When the optocoupler IC505 is turned on, the 5V voltage connected to the collector flows to the cold ground, forming a low-level feedback signal. When the optocoupler IC505 is turned off, the 5V voltage connected to the collector flows to the control module, forming a high-level feedback signal, thereby accurately conveying the feedback signal output from the Vfg port to the control module. Here, the closer capacitor C523 is to the control module, the better it is at filtering out feedback signal noise.

[0049] The fan drive circuit provided in the embodiment of the present application is as follows Figure 3 As shown, it can be seen that the fan drive circuit provided in the embodiment of the present application is Figure 2 Based on the circuit shown, the optocoupler IC504, optocoupler IC505, and resistor R520 are cancelled, and the transistor Q504 and resistor R532 are added; and the hot ground of the circuit on the left side of the original optocoupler IC504 and optocoupler IC505 is connected to the cold ground of the circuit on the right side. At this time, the hot ground and the cold ground have the same potential, and the hot ground and the cold ground are collectively referred to as ground here.

[0050] Among them, the improved parts include: port Vsp is connected to resistor R517, then connected to capacitor C521, transient suppression diode DZ510, electrolytic capacitor E521, resistor R518, then connected to resistor R519, and finally connected to the collector of transistor Q504. The emitter of transistor Q504 is connected to the power supply voltage of 12.5V and 750mA and resistor R526 respectively. The other end of resistor R526 is connected to the base of transistor Q504 and resistor R532 respectively. The other end of resistor R532 is connected to the collector of transistor Q503; port Vfg is connected to capacitor C522, resistor R521 and resistor R522 respectively. The other end of capacitor C522 is grounded. The other end of resistor R521 is connected to the power supply voltage of 5V. The other end of R522 sends the feedback signal 24T_DCFAN1-F and is connected to capacitor C523. The other end of capacitor C523 is grounded.

[0051] In actual application, transistor Q504 can be a PNP type transistor, which is turned on when the base potential is low; transistor Q503 can be an NPN type transistor, which is turned on when the base potential is high; the control module can be an MCU, and the square wave signal (PWM wave, which can be 1Khz) sent by the MCU on the main control board is at a high level, which turns on transistor Q503, and the power supply 12.5V flows into the ground through the transistor Q503 through the resistors, reducing the base voltage of the transistor Q504, turning on the transistor Q504, and allowing the 12.5V power supply voltage to charge the integration circuit composed of resistor R518 and electrolytic capacitor E521, converting the time integral of the input square wave signal into an output voltage, raising the voltage value of the port Vsp, and when the duty cycle of the square wave signal increases, the voltage on the electrolytic capacitor E521 increases, and vice versa, the voltage decreases.

[0052] The Vfg port of the driver module directly outputs a feedback signal, which is a square wave signal with different duty cycles generated based on the motor speed. The feedback signal is input to the MCU of the main control board for processing. The MCU calculates the actual motor speed based on the feedback square wave signal, compares it with the control set speed, and adjusts the control duty cycle according to the deviation between the two.

[0053] It is understandable that by connecting the hot ground (i.e., the first ground) and the cold ground (i.e., the second ground) of a traditional air conditioner, the reference potential of the control module is made the same as the reference potential of the drive module, thereby making the drive signal sent by the control module and the signal that can be received by the fan at the same potential reference. In this way, the solution provided by the embodiment of the present application can eliminate the optocoupler on the fan drive circuit and maintain effective communication between the control device and the fan, reducing the size of the PCB in the air conditioner and facilitating the development of miniaturized electronic controls. In addition, by directly connecting the cold ground and the hot ground, while reducing the optocoupler, the changes to the internal circuit of the air conditioner are minimized, and the wiring length of the circuit is effectively shortened.

[0054] In the related art, the DC fan of the air conditioner is prone to making a sound similar to "tidal waves" during operation, which affects the user's experience of the product.

[0055] Based on this, in some embodiments, the circuit further includes a switching power supply, which is used to at least provide a first power supply to the first port; in the switching power supply, the branch where the port of the first power supply is located includes a feedback circuit.

[0056] here, Figure 2The 12.5V, 750mA power supply voltage is collected from the branch of the feedback circuit in the switching power supply. During the development of the all-in-one air conditioner, the inventors of this application discovered that the electronic expansion valve of the air conditioner would generate electromagnetic interference to the external circuit when in operation, and the drive signal for driving the fan was easily interfered with, causing a "tidal" sound to be heard by the user when the fan was running. Therefore, the power source of the Vsp port (first port) of the fan drive module was switched to the branch of the feedback circuit on the switching power supply. This improved the stability of the power supply of the fan control circuit and avoided the "tidal" sound caused by the branch power provided by the switching power supply being disturbed when the electronic expansion valve of the air conditioner was in operation, thereby improving the user's experience of the product. In actual application, the power supply of the feedback circuit in the switching power supply is not necessarily 12.5V and 750mA. The specific values ​​of the power supply voltage and current can be set according to actual needs, and this application does not limit this.

[0057] Accurate voltage regulation of switching power supplies requires an efficient feedback regulation mechanism.

[0058] Based on this, in some embodiments, the switching power supply includes a switching power supply chip, the feedback circuit includes a voltage stabilizing module and a first optical coupler; the voltage stabilizing module includes a second port, a third port and a fourth port;

[0059] The voltage stabilizing module is configured to: when the voltage of the second port exceeds a first voltage threshold, conduction is performed between the third port and the fourth port, so that conduction is performed between the collector and the emitter of the first optical coupler, and the switching power supply chip receives a first signal;

[0060] The first signal is used to instruct the switching power supply chip to reduce the voltage of the first power supply.

[0061] Here, when the voltage at the second port exceeds the preset threshold, the internal conduction of the voltage regulator module activates the first optocoupler, sending a voltage reduction signal to the switching power supply chip. This design builds a fast-response closed-loop voltage regulation system and realizes signal coupling between the high and low voltage sides through optocoupler isolation, ensuring that the switching power supply chip obtains voltage abnormality signals in real time and quickly adjusts the output, significantly improving the power supply output accuracy and dynamic response capability.

[0062] The operation of the voltage regulator module relies on a sophisticated internal structure.

[0063] Based on this, in some embodiments, the voltage stabilizing module also includes an operational amplifier and a transistor, the second port is connected to the positive input terminal of the operational amplifier, the output terminal of the operational amplifier is connected to the base of the transistor, the collector of the transistor is connected to the third port, and the emitter of the transistor is connected to the fourth port.

[0064] In practical applications, the op amp's inverting input is connected to an internal 2.5V reference source, and its second port is connected to the op amp's positive input for voltage sampling. When the voltage at the second port exceeds 2.5V, the op amp drives the transistor base, controlling the transistor's collector and emitter to conduct, thereby turning on the third and fourth ports. This design utilizes the op amp's high gain to amplify the voltage deviation signal and, combined with the transistor's switching characteristics, achieves precise threshold triggering, enabling the voltage regulator module to more sensitively respond to voltage fluctuations and improve the accuracy and reliability of feedback control. Specifically, the voltage regulator module can use the TL431 adjustable shunt regulator.

[0065] The signal interaction between the switching power supply chip and the feedback circuit requires a stable connection architecture.

[0066] Based on this, in some embodiments, the switching power supply chip includes a fifth port; the port of the first power supply is connected to the second port through a first resistor, the fifth port is connected to the collector of the first optocoupler, and the emitter of the first optocoupler is connected to the first ground.

[0067] Reasonable selection of resistor values ​​forms a stable voltage divider network, which can proportionally convert the high voltage signal into a safe voltage suitable for detection by the voltage regulator module, ensuring that the second port accurately reflects the power output status in real time and provides a reliable front-end signal for voltage regulation control.

[0068] Based on this, in some embodiments, one end of the first resistor is connected to the port of the first power supply, and the other end is respectively connected to the second port and the second resistor, and the second resistor is connected to the second ground.

[0069] Here, in actual application, since the hot ground and the cold ground are already connected, the first ground and the second ground are actually the same ground. The first power port is connected to the second port of the voltage regulator module through the first resistor, and the other end of the first resistor is respectively connected to the second port of the voltage regulator module and the second resistor, and the second resistor is grounded. In this way, the 12.5V power supply voltage can be divided by the first resistor and the second resistor, so that the second port of the voltage regulator module receives a lower voltage (such as less than or equal to 2.5V). When the power supply voltage 12.5V increases abnormally, the voltage received by the second port will also increase. When it exceeds 2.5V, the voltage regulator module turns on the optocoupler, so that the switching power supply chip receives a low-level signal, and the switching power supply chip begins to control the 12.5V voltage to drop.

[0070] When the cold ground and the hot ground are connected, there is a risk of electric shock where the air conditioner comes into contact with people.

[0071] Based on this, in some embodiments, the air conditioner further includes a touch module and / or a display module;

[0072] The switching power supply module is further configured to provide a second power supply to at least the touch control module and / or the display module;

[0073] The touch module and / or the display module is connected to a third ground, and the third ground is isolated from the first ground and the second ground.

[0074] Here, the switching power supply provides a second, separately grounded power source for the user-accessible display or touchpad. This power source is completely isolated from the ground connected to the driver and control modules within the air conditioner, ensuring user safety. For example, the third ground can be designed as a floating ground or powered by an independent transformer, ensuring its potential is independent of the mains. Therefore, by providing a separate ground for user-accessible components, while also providing a balanced balance between cost, reliability, and safety, based on the hot and cold grounding of the secondary side of the switching power supply transformer.

[0075] Accurate control of fan speed requires real-time speed feedback.

[0076] Based on this, in some embodiments, the driving module further includes a sixth port, and the sixth port is used to output a feedback signal;

[0077] The feedback signal includes the rotation speed information of the fan;

[0078] The control module is further configured to receive the feedback signal and output the driving signal based on the feedback signal.

[0079] In some embodiments, the control module is specifically configured to:

[0080] outputting a drive signal based on first speed information, wherein the first speed information includes a target speed of the fan;

[0081] receiving the feedback signal, and determining second speed information based on the feedback signal, wherein the second speed information includes an actual speed of the fan;

[0082] If it is determined based on the first speed information and the second speed information that the target speed is different from the actual speed, the duty cycle of the driving signal is adjusted until the actual speed is the same as the target speed.

[0083] Here, the sixth port in the driver module is the speed feedback signal port Vfg. In actual application, the Vfg port outputs a feedback signal containing speed information to the MCU. The MCU dynamically adjusts the drive signal according to the actual fan speed contained in the feedback signal, realizing real-time monitoring and compensation of the fan speed, ensuring that the fan can operate at the expected speed under different working conditions, and improving the operating efficiency and stability of the air conditioner.

[0084] Since the cold ground and hot ground inside the air conditioner are connected together, the PCB board of the main control circuit faces environmental reliability challenges.

[0085] Based on this, in some embodiments, the bottom of the PCB where the control module is located is wrapped with a plastic shell made of ABS material, and the outside of the plastic shell is wrapped with fireproof sheet metal.

[0086] Here, the ABS material has good insulation properties, and the fireproof sheet metal provides mechanical protection and flame retardancy, meeting stringent safety certification requirements. This design significantly improves the environmental adaptability of the control module and ensures circuit safety. In actual application, you can use ABS plastic with a thickness of 2.6mm that meets the 5VA certification requirements and fireproof sheet metal with a thickness of 1mm. To ensure safety, when designing the PCB board, you can also set the electrical clearance and creepage distance of the PCB board to be greater than the national standard. Specifically, the electrical clearance of the PCB board can be no less than 3.2mm, and the creepage distance can be no less than 4.0mm. The PCB where the control module is located can only include the weak current circuits in the air conditioner, while in the all-in-one solution, the printed circuit board PCB can include all the circuits in the air conditioner (such as the fan drive circuit, switching power supply, etc.). The embodiment of the present application does not limit the specific circuits on the PCB.

[0087] The fan drive circuit provided by the embodiment of the present application includes: a control module for sending a drive signal for driving the fan; a drive module for driving the fan to operate, the drive module including a first port, the first port being used to receive the drive signal; wherein the drive module is connected to a first ground, and the control module is connected to a second ground; the first ground is connected to the second ground; the first ground represents a ground terminal that is not isolated from the mains power, and the second ground represents a ground terminal that is isolated from the mains power; during the transmission of the drive signal, the drive signal does not pass through an optocoupler. By connecting the hot ground (i.e., the first ground) and the cold ground (i.e., the second ground) of the traditional air conditioner, the reference potential of the control module is made the same as the reference potential of the drive module, so that the drive signal sent by the control module and the signal that can be received by the fan are at the same potential reference. In this way, the solution provided by the embodiment of the present application can eliminate the optocoupler on the fan drive circuit and maintain effective communication between the control module and the fan, reducing the size of the PCB in the air conditioner, which is conducive to the development of miniaturized electronic control.

[0088] An embodiment of the present application further provides an air conditioner, which includes a fan and a fan driving circuit corresponding to the various embodiments described above.

[0089] The present application is described in further detail below with reference to application examples.

[0090] In an application example of this application, the fan drive circuit simulation schematic diagram is as follows: Figure 4As shown in the figure, the simulation tool used is LTspice, V(Vb1) represents the voltage of the PWM wave input by the MCU, V(Vb2) represents the base voltage of the transistor Q504, V(vout) represents the voltage value of the electrolytic capacitor, that is, the voltage value received by the Vsp port, Ie(Q504) and Ib(Q504) represent the emitter current and base current of the transistor Q504 respectively, Ib(Q503) and Ic(Q503) represent the base current and collector current of the transistor Q503 respectively; it can be seen that when the PWM wave input by the MCU is at a high level, the transistor Q503 is turned on, Vb2 changes from a high level to a low level, and the transistor Q504 is turned on, so that the 12.5V power supply can charge the electrolytic capacitor E521. Since the duty cycle of the PWM wave does not change, V(vout) also does not change.

[0091] The circuit diagram of the switching power supply provided in the application example of this application is as follows: Figure 5 As shown, since the cold ground and hot ground are already connected, connecting to the cold ground and the hot ground is essentially the same, and is hereinafter referred to as grounding. Ports 7 and 8 of the switching power supply chip IC401 are connected, and are respectively connected to the anode of diode D401 and terminal 3 of the primary winding of transformer T401. The cathode of diode D401 is respectively connected to capacitor C401 and resistor R411. The other ends of capacitor C401 and resistor R411 are connected to terminal 1 of the primary winding of transformer T401, and are connected to the DC bus power supply P+.

[0092] The five terminals of the switching power supply chip IC401 are connected to the cathodes of electrolytic capacitor E406, capacitor C402, and diode D402, respectively. The other terminals of electrolytic capacitors E406 and C402 are grounded. The anode of diode D402 is connected to resistor R409. The other terminal of R409 is connected to the five terminals of the auxiliary winding and the anode of diode D405, respectively. The cathode of diode D405 is connected to electrolytic capacitor E401 and capacitor C403, respectively. The switching power supply chip IC401 outputs a +15V, 100mA power supply. The other terminals of electrolytic capacitors E401 and C403 are grounded. The 1st port of the switching power supply chip IC401 is connected to the resistor R2, the resistor R3, the resistor R4, and the resistor R5 respectively and then grounded. The 2nd and 3rd ports of the switching power supply chip IC401 are grounded. The 4th port of the switching power supply chip IC401 (i.e., the fifth port mentioned above) is connected to the collector of the optocoupler IC403 and the capacitor C412 respectively. The other end of the capacitor C412 is grounded. The emitter of the optocoupler IC403 is grounded. The anode of the diode of the optocoupler IC403 is connected to the resistor R404 and the resistor R405 respectively. The cathode of the diode of the optocoupler IC403 is connected to the other end of R405 and the capacitor C408 respectively. The voltage stabilizing module The cathode of block IC404 (i.e. the above-mentioned third port), the anode of the voltage stabilizing module IC404 (i.e. the above-mentioned fourth port) are grounded, the reference end of the voltage stabilizing module IC404 (i.e. the above-mentioned second port), the reference end of the voltage stabilizing module IC404 is connected to resistor R406, the other end of resistor R406 is connected to the other end of capacitor C408, the other end of resistor R404 is connected to a +12.5V, 750mA power supply, and is connected to resistor R407, the other end of resistor R407 is respectively connected to the other end of R406, resistor R408, and resistor R411, and the other ends of resistors R408 and R411 are grounded.

[0093] Terminal 10 of the secondary winding of transformer T401 is connected to the anode of diode D404, the cathode of diode D404 is connected to electrolytic capacitor E408 and capacitor C404 respectively, and outputs a +12V, 500mA power supply (i.e., the above-mentioned second power supply). The other ends of electrolytic capacitor E408 and capacitor C404 are separately grounded (i.e., the above-mentioned third ground) and are respectively connected to terminal 9 of the secondary winding of transformer T401 and capacitor C425. The other end of capacitor C425 is connected to capacitor C426, and the other end of capacitor C426 is grounded.

[0094] Terminals 7 of the secondary winding of transformer T401 are connected to the anode of diode D406, the anode of diode D403, and capacitor C418, respectively. The other end of capacitor C418 is connected to resistors R425 and R426, respectively. The other ends of resistors R425 and R426 are connected to the cathodes of diode D406 and diode D403, and are also connected to terminals 4 of the auxiliary winding of transformer T401, electrolytic capacitors E404, E402, C411, C413, and C419, respectively. The other ends of electrolytic capacitors E404, E402, C411, C413, and C419 are all grounded. The cathodes of diodes D406 and D403 are connected to a +12.5V, 750mA power supply.

[0095] The operating principle of the switching power supply includes: the DC bus voltage P+ enters the primary coil 1 end of the transformer T401, and provides power to the switching power supply chip IC401 from the primary coil 3 end. The 4th port of the switching power supply chip generates power through the internal circuit of the module to charge the electrolytic capacitor E406 and capacitor C402 connected to the 5th port. After the voltage of the 5th port reaches a certain threshold, the switching power supply chip IC401 works and generates a PWM square wave inside it to control the internal switching tube. The transformer T401 outputs the following three voltages: +15V / 100mA, which is mainly used to power the compressor frequency conversion module (in the traditional power supply scheme, +15V is also used to power the fan drive circuit); +12V / 500mA, which powers the electronic control module that can be touched by the human body (such as the touch panel, display screen, etc.); +12.5V / 750mA, which is used to drive the relay, expansion valve and the fan drive circuit provided in the embodiment of the present application.

[0096] If the +12.5V voltage output by the secondary side of the switching power supply becomes higher due to reasons such as higher mains voltage or electromagnetic interference, the voltage divided by the sampling voltage divider circuit composed of resistors R407, R408, and R421 connected at +12.5V will also become higher. This voltage is sent to the reference end of the voltage regulator module IC404. When the voltage reaches +2.5V, the cathode and anode of IC404 are turned on, and the voltage difference across the diode of the optocoupler IC403 causes it to emit light, so that the collector and emitter of the optocoupler IC403 are also turned on, and the voltage of the 4-port of the switching power supply chip is pulled down. At this time, the duty cycle of the PWM square wave controlled by the switching power supply chip IC401 becomes smaller, the operating frequency of the switching tube inside the chip becomes lower, the voltage of the primary coil of the transformer becomes lower, and the induced voltage of the secondary coil also becomes lower, thereby pulling down the output high voltage and quickly adjusting it to the normal +12.5V. On the other hand, if the mains input voltage is too low or the load is too heavy and the current is too high, the secondary voltage is pulled down, the voltage value obtained by the sampling voltage divider circuit becomes low, and the voltage sent to the reference terminal of the voltage regulator module IC404 does not reach the +2.5V reference voltage. The anode and cathode of IC404 are not conducting, and the collector and emitter of the optocoupler IC403 are not conducting. As a result, the voltage at the 4-port of the switching power supply chip IC401 becomes higher, the duty cycle of the PWM square wave inside the chip increases, the operating frequency of the switching tube increases, the voltage of the primary winding of the transformer also increases, and the induced voltage of the secondary winding increases. At this time, the low output voltage is raised to the normal +12.5V. Therefore, in actual application, switching the power supply connected to the Vsp port of the driver module from the 15V branch of the switching power supply to the 12.5V branch can quickly adjust the power supply voltage when the power provided by the switching power supply is disturbed when the electronic expansion valve of the air conditioner is activated, reducing voltage fluctuations, thereby avoiding the "tidal" sound similar to the fan operation, and improving the user experience of the product.

[0097] The waveform diagram of the Vsp port voltage connected to the +15V / 100mA power supply provided in the application example of this application is as follows Figure 6 As shown, it can be seen that when the electronic expansion valve of the air conditioner is activated, the voltage of the +15V branch of the switching power supply (as shown by the line in the box) will be periodically disturbed. If the Vsp port of the drive module is connected to a +15V power supply, the Vsp port voltage (as shown by the line without a frame) will fluctuate, thereby affecting the speed control of the fan. The fan will make a sound similar to "tidal waves", affecting the user's experience of the product.

[0098] The simulation waveform diagram of the Vsp port voltage connected to the +15V / 100mA power supply provided in the application example of this application is as follows Figure 7As shown, it can be seen that when the branch where the switching power supply +15V voltage (as shown by the unframed line) is located is not disturbed by the action of the electronic expansion valve, the Vsp port voltage of the driving module, that is, the curve of V(Vsp1) is smooth, and will not affect the speed control of the fan; when the branch where the switching power supply +15V voltage (as shown by the line in the frame) is located is disturbed by the action of the electronic expansion valve, the Vsp port voltage of the driving module, that is, the curve of V(Vsp1) will fluctuate, which will affect the speed control of the fan and cause a "tidal" sound when the fan is running.

[0099] The signal waveform diagram of port Vsp and port Vfg after removing the optical coupler provided in the application example of this application is as follows Figure 8 As shown in the figure, after the optocoupler is removed from the fan drive circuit, whether there is coupling interference after the power ground (hot ground) and the signal ground (cold ground) are connected is detected. It can be seen that based on the solution of the above embodiment, the control signal (dark curve), that is, the signal received by the Vsp port, and the feedback signal (light curve), that is, the signal sent by the Vfg port, have no glitch interference, so the drive module can still communicate normally with the MCU.

[0100] The DC fan control logic diagram provided in this application example is as follows Figure 9 As shown, the control logic is applied to the control module, including:

[0101] Step 901: Power on to control the fan to rotate, and then execute step 902;

[0102] Step 902, set the DC motor speed r1, and then execute step 903;

[0103] Step 903, calculate the speed r2 based on the feedback signal, and then execute step 904;

[0104] Step 904, determine whether r1 is equal to r2, if so, execute step 906, if not, execute step 905;

[0105] Step 905, adjust the square wave duty cycle, and then execute step 903;

[0106] Step 906: Output according to the duty cycle.

[0107] Here, after the fan is powered on, the control module outputs a drive signal (such as a 1Khz PWM wave) to the Vsp port of the driver module according to the speed r1 to control the fan to rotate at the speed r1, and obtains a feedback signal from the Vfg port of the driver module. The feedback signal contains the actual fan speed, that is, r2. When r1 and r2 are different, the duty cycle of the drive signal is adjusted until r1 and r2 are the same, so as to ensure that the fan runs at the expected speed and improve the operating efficiency and stability of the air conditioner.

[0108] From the above description, it can be seen that the power supply +12.5V / 750mA branch is the output with the largest load output and the best anti-interference degree of the flyback switching power supply. Since the power supply negative feedback selects this branch, when the power supply voltage of this branch is disturbed, the power supply +12.5V / 750mA is quickly adjusted through the feedback circuit where TL431 is located. When the solution of this application is aimed at the overall air-conditioning unit, the elimination of the optocoupler is beneficial to the PCB layout and wiring, simplifies the circuit design, and makes the circuit more reliable and maintainable. When it comes to the indoor unit of the split unit, if there are two fans in the indoor unit, whether the fan IPM (Intelligent Power Module) is integrated with the fan (built-in solution) or the fan IPM is set on the main control board (external solution), the switching power supply circuit structure of the overall unit can be used (such as Figure 5 As shown), and there is no need to set up a 7815 three-terminal regulator at the 15V power port, and use the improved DC fan control circuit, that is, the fan drive circuit (as shown Figure 3 As shown in the figure, the optocoupler between the main control chip and the driver chip is eliminated, which simplifies the circuit design and facilitates the PCB wiring layout under the requirement of miniaturization of electronic control.

[0109] In summary, this application provides a control circuit for DC motor speed regulation. The control circuit is built with basic components, which greatly simplifies the circuit design and implementation process, making the circuit more reliable and maintainable. At the same time, circuit simulation is also performed on the control circuit. The simulation tool uses LTspice. The basic components have good usability and cost-effectiveness, making the entire design more economical.

[0110] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0111] In addition, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the embodiments of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. It should be noted that: "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0112] It should be understood that references throughout this specification to "some embodiments" mean that a particular feature, structure, or characteristic associated with an embodiment is included in at least one embodiment of the present application. Therefore, the appearance of "in some embodiments" throughout this specification does not necessarily refer to the same embodiment. Furthermore, these particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments, provided they do not conflict.

[0113] The term "and / or" in this article is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0114] In the description of the embodiments of the present application, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" or "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be internal communication between two elements or an interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0115] The above description is merely a preferred embodiment of the present application and is not intended to limit the scope of patent protection of the present application. Any equivalent structural transformations made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the scope of patent protection of the present application.

Claims

1. A fan drive circuit for an air conditioner, characterized in that: include: A control module, used for sending a driving signal for driving the fan; A driving module, configured to drive the fan to operate, the driving module comprising a first port, the first port being configured to receive the driving signal; Wherein, the driving module is connected to a first ground, and the control module is connected to a second ground; the first ground is connected to the second ground; the first ground represents a ground terminal that is not isolated from the mains power, and the second ground represents a ground terminal that is isolated from the mains power; During the transmission of the driving signal, the driving signal does not pass through the optical coupler.

2. The circuit according to claim 1, wherein: The circuit further includes a switching power supply, which is configured to provide at least a first power source to the first port. In the switching power supply, the branch where the port of the first power source is located includes a feedback circuit.

3. The circuit according to claim 2, characterized in that The switching power supply includes a switching power supply chip, and the feedback circuit includes a voltage stabilizing module and a first optical coupler; the voltage stabilizing module includes a second port, a third port and a fourth port; The voltage stabilizing module is configured to: when the voltage of the second port exceeds a first voltage threshold, conduction is performed between the third port and the fourth port, so that conduction is performed between the collector and the emitter of the first optical coupler, and the switching power supply chip receives a first signal; The first signal is used to instruct the switching power supply chip to reduce the voltage of the first power supply.

4. The circuit according to claim 3, characterized in that The voltage stabilizing module also includes an operational amplifier and a transistor, the second port is connected to the positive input terminal of the operational amplifier, the output terminal of the operational amplifier is connected to the base of the transistor, the collector of the transistor is connected to the third port, and the emitter of the transistor is connected to the fourth port.

5. The circuit according to claim 3, characterized in that The switching power supply chip includes a fifth port; the port of the first power supply is connected to the second port through a first resistor, the fifth port is connected to the collector of the first optocoupler, and the emitter of the first optocoupler is connected to the first ground.

6. The circuit according to claim 5, characterized in that One end of the first resistor is connected to a port of the first power supply, and the other end is connected to the second port and the second resistor respectively. The second resistor is connected to the second ground.

7. The circuit according to claim 1, characterized in that The air conditioner further includes a touch module and / or a display module; The switching power supply module is further configured to provide a second power supply to at least the touch control module and / or the display module; The touch module and / or the display module is connected to a third ground, and the third ground is isolated from the first ground and the second ground.

8. The circuit according to claim 1, wherein: The driving module further includes a sixth port, and the sixth port is used to output a feedback signal; The feedback signal includes the rotation speed information of the fan; The control module is further configured to receive the feedback signal and output the driving signal based on the feedback signal.

9. The circuit according to claim 8, characterized in that The control module is specifically used to: outputting a drive signal based on first speed information, wherein the first speed information includes a target speed of the fan; receiving the feedback signal, and determining second speed information based on the feedback signal, wherein the second speed information includes an actual speed of the fan; If it is determined based on the first speed information and the second speed information that the target speed is different from the actual speed, the duty cycle of the driving signal is adjusted until the actual speed is the same as the target speed.

10. The circuit according to any one of claims 1 to 9, characterized in that: The bottom of the printed circuit board PCB where the control module is located is wrapped with a plastic shell made of ABS material, and the outside of the plastic shell is wrapped with fireproof sheet metal.

11. An air conditioner, characterized in that: The invention comprises a fan and a fan driving circuit according to any one of claims 1 to 10.

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