Electronic expansion valve control circuit and electrical equipment
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-15
- Publication Date
- 2026-08-14
AI Technical Summary
[0007]本实用新型实施例提供一种电子膨胀阀控制电路及电器设备，以至少解决现有技术中电子膨胀阀的开关噪声会对控制器及周围带电设备造成干扰的问题
[0025]应用本实用新型的技术方案，在MCU与驱动芯片之间设置光耦隔离电路，使得MCU输出的控制信号与驱动芯片输出的驱动信号隔离，且MCU及光耦输入端与驱动芯片、电子膨胀阀及光耦输出端使用相互隔离的电源进行供电，避免了电源之间的相互串扰，实现了电子膨胀阀的控制端与驱动端在控制和电源上的隔离，减少了控制线路与驱动线路之间的相互干扰，电子膨胀阀驱动线路中的干扰无法传递到MCU控制端，减少了电子膨胀阀线圈所引起的电磁干扰，避免电子膨胀阀动作时产生的开关噪声对MCU造成干扰导致控制失常，也避免电子膨胀阀动作时产生的开关噪声对周围带电设备的电磁干扰，保证控制器以及周围带电设备运行的稳定性，解决了电子膨胀阀的开关噪声会对控制器及周围带电设备造成干扰的问题。
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Figure CN224635643U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of equipment control technology, and more specifically, to an electronic expansion valve control circuit and electrical equipment. Background Technology
[0002] As a core component of refrigeration equipment (such as air conditioners and refrigerators) that regulates the flow of refrigerant, the electronic expansion valve needs to be controlled to achieve an accurate opening degree.
[0003] The working principle of the electronic expansion valve is to use a stepper motor to control the valve needle. The stepper motor includes a stator and a rotor. The controller MCU sends a control signal to apply a pulse voltage to the stator winding (i.e., coil), which drives the rotor to move and change the valve needle opening to achieve flow regulation.
[0004] The coil of an electronic expansion valve is an inductive load. During the operation of the electronic expansion valve, the charging and discharging of the coil generates noise, i.e., the coil of the electronic expansion valve produces switching noise. The switching noise of the electronic expansion valve can not only interfere with the controller, causing it to malfunction, but also cause electromagnetic interference and affect surrounding electrical equipment.
[0005] If the electronic expansion valve operates for an extended period of time, it will cause the coil temperature to rise, the internal resistance to increase, the power loss to increase, and the efficiency to decrease. This will lead to an increase in the coil current, which will exacerbate the switching noise of the electronic expansion valve and thus intensify electromagnetic interference.
[0006] There is currently no effective solution to the problem that the switching noise of electronic expansion valves in existing technologies can interfere with the controller and surrounding electrical equipment. Utility Model Content
[0007] This utility model provides an electronic expansion valve control circuit and electrical equipment to at least solve the problem in the prior art that the switching noise of the electronic expansion valve will interfere with the controller and surrounding electrical equipment.
[0008] To solve the above-mentioned technical problems, this utility model provides an electronic expansion valve control circuit, including:
[0009] The controller MCU is used to output control signals;
[0010] A driver chip is connected to the electronic expansion valve and is used to drive the electronic expansion valve to operate according to the control signal.
[0011] An optocoupler isolation circuit is connected between the MCU and the driver chip. The optocoupler isolation circuit includes an optocoupler input terminal and an optocoupler output terminal.
[0012] A switching power supply is used to output a first power supply and a second power supply that are independently isolated from each other. The first power supply powers the MCU and the optocoupler input terminal, and the second power supply powers the driver chip, the electronic expansion valve and the optocoupler output terminal.
[0013] Optionally, the optocoupler isolation circuit includes at least one optocoupler, the number of which is equal to the number of control signals output by the MCU;
[0014] The optical input terminal of the at least one optocoupler is connected to at least one control signal output terminal of the MCU in a one-to-one correspondence.
[0015] The output terminal of the at least one optocoupler is connected to at least one control signal input terminal of the driver chip in a one-to-one correspondence.
[0016] Optionally, the positive terminal of the optocoupler input is connected to the first power supply through a current-limiting resistor; the negative terminal of the optocoupler input is connected to the control signal output terminal of the MCU; and the positive terminal of the optocoupler input is also connected to the negative terminal of the optocoupler input through a filter capacitor.
[0017] Optionally, the collector of the optocoupler output terminal is connected to the control signal input terminal of the driver chip; the collector of the optocoupler output terminal is also connected to the second power supply through a pull-up resistor; and the emitter of the optocoupler output terminal is grounded.
[0018] Optionally, the switching power supply includes a transformer, the transformer including at least two secondary coils, the transformer outputting the first power supply and the second power supply through different secondary coils.
[0019] Optionally, the switching power supply further includes a Y capacitor, one end of which is connected to the primary bus of the transformer, and the other end of which is connected to the ground terminal of the secondary coil of the transformer used to output the second power supply.
[0020] Optionally, the MCU includes:
[0021] A timing module is used to record the continuous operating time of the electronic expansion valve;
[0022] The control module is used to stop outputting control signals to stop the electronic expansion valve from operating when the continuous operation time reaches a first preset time, and to continue outputting control signals to stop the electronic expansion valve from operating after a second preset time, and so on, until the electronic expansion valve reaches the target number of steps.
[0023] Optionally, the first preset time is longer than the second preset time.
[0024] This utility model embodiment also provides an electrical device, including: an electronic expansion valve and the electronic expansion valve control circuit described in this utility model embodiment.
[0025] By applying the technical solution of this utility model, an optocoupler isolation circuit is set between the MCU and the driver chip, which isolates the control signal output by the MCU from the drive signal output by the driver chip. Furthermore, the MCU and optocoupler input terminals are powered by mutually isolated power supplies from the driver chip, electronic expansion valve, and optocoupler output terminals, avoiding crosstalk between power supplies. This achieves isolation between the control and drive terminals of the electronic expansion valve in terms of control and power supply, reducing mutual interference between the control and drive circuits. Interference in the electronic expansion valve drive circuit cannot be transmitted to the MCU control terminal, reducing electromagnetic interference caused by the electronic expansion valve coil. This prevents the switching noise generated when the electronic expansion valve operates from interfering with the MCU and causing control malfunctions, and also prevents electromagnetic interference from the switching noise generated when the electronic expansion valve operates on surrounding electrical equipment. This ensures the stability of the controller and surrounding electrical equipment, solving the problem of interference caused by the switching noise of the electronic expansion valve to the controller and surrounding electrical equipment. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the control circuit for an existing electronic expansion valve;
[0027] Figure 2 This is a schematic diagram of the control principle of an existing electronic expansion valve;
[0028] Figure 3 This is a schematic diagram of the electronic expansion valve control circuit provided in this embodiment of the utility model. Figure 1 ;
[0029] Figure 4 This is a schematic diagram of the electronic expansion valve control circuit provided in this embodiment of the utility model. Figure 2 ;
[0030] Figure 5 This is a schematic diagram of the electronic expansion valve control circuit provided in this embodiment of the utility model;
[0031] Figure 6 This is a flowchart of the electronic expansion valve control method provided in this embodiment of the utility model;
[0032] Figure 7 This is a flowchart of the intermittent control method for the electronic expansion valve provided in this embodiment of the utility model. Detailed Implementation
[0033] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0034] It should be noted that the terms "first," "second," etc., used in the specification, claims, and drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0035] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.
[0036] The optional embodiments of this utility model are described in detail below with reference to the accompanying drawings.
[0037] like Figure 1 The diagram shows a schematic of a prior art electronic expansion valve control circuit. L1 is the high-frequency transformer of the switching power supply, CL is the bus capacitor, U7 is the PWM controller, and U6 is an optocoupler bridging high and low voltage circuits. These components, along with diodes D1 and D2 and capacitors C1, C2, and C10, constitute the switching power supply. The 220V AC mains power is rectified to 310V DC. The switching power supply converts this 310V DC to the required power (e.g., 12V) to power the controller MCU, driver chip U5, and electronic expansion valve EXV. PWM_CTR controls the conduction of the primary coil of the transformer, thereby transferring the voltage from the primary coil to the secondary winding. Diodes D1 and D2 are rectifier diodes, conducting in one direction, allowing capacitors C1, C2, and C10 to charge and form a voltage. Unconnected terminals in the secondary coil of transformer L1 can output the required power for other circuits, such as an 18V output.
[0038] The power supply VCC_AUX supplies power to the PWM controller U7 through the output of optocoupler U6. The input of optocoupler U6, together with the 12V power supply output by the switching power supply and the voltage reference Vref, forms a voltage sampling to form a stable 12V power supply. This 12V power supply is then converted by the power converter U8 (e.g., DC-DC topology) to supply power to the MCU.
[0039] Taking an air conditioner as an example, the outdoor unit sends the target number of steps required by the electronic expansion valve to the MCU. The MCU implements the control cycle of the electronic expansion valve. U5 is the driver chip for the electronic expansion valve, which realizes the driving function of the electronic expansion valve. EXV1, EXV2, EXV3, and EXV4 are the control signals for the electronic expansion valve. The MCU outputs control signals according to the target number of steps sent by the outdoor unit to make the electronic expansion valve perform forward and reverse rotation.
[0040] The coil of the electronic expansion valve is divided into two parts, each part has two windings, for a total of four windings. Each winding corresponds to one phase, that is, four phases. The common terminal of the windings is connected to the power supply.
[0041] exist Figure 1 In the diagram, cross intersections with solid dots indicate that they are connected, while T-shaped intersections are connected by default.
[0042] like Figure 2 The diagram shown illustrates the control principle of an existing electronic expansion valve, demonstrating the correspondence between excitation methods and valve opening / closing. Taking a four-phase eight-step stepper motor as an example, energizing one winding first, then two windings, requires eight energizations to complete one control cycle. This driving method is called four-phase eight-step. Energizing in a 1-2-1-2 phase sequence is called 1-2 phase excitation. If two windings are energized each time, four energizations are required to complete one control cycle. This driving method is called four-phase four-step. Energizing two windings each time is called 2-phase excitation, also known as 2-2 phase excitation. This is not shown in this embodiment. Phase A, Phase B, ... Mutually, The phase is controlled by four control signals EXV1, EXV2, EXV3, and EXV4.
[0043] If it is necessary to increase the opening of the electronic expansion valve, the MCU outputs EXV1, EXV2, EXV3, and EXV4 in a positive phase sequence, i.e. Figure 2 The valve opening direction is shown. If it is necessary to reduce the opening of the electronic expansion valve, the MCU outputs EXV4, EXV3, EXV2, and EXV1 in reverse timing sequence, i.e. Figure 2 The valve closing direction is shown.
[0044] Example 1
[0045] To address the problem that the switching noise of electronic expansion valves in existing technologies can interfere with the controller and surrounding electrical equipment, this embodiment provides an electronic expansion valve control circuit. Figure 3 This is a schematic diagram of the electronic expansion valve control circuit provided in this embodiment of the utility model. Figure 1 ,like Figure 3 As shown, the electronic expansion valve control circuit includes: a controller MCU 10, a driver chip 20, an electronic expansion valve 30, an optocoupler isolation circuit 40, and a switching power supply 50.
[0046] MCU 10 is used to output control signals.
[0047] The driver chip 20 is connected to the electronic expansion valve 30 and is used to drive the electronic expansion valve 30 to operate according to the control signal.
[0048] Optical isolation circuit 40 is connected between the MCU 10 and the driver chip 20. The optical isolation circuit 40 includes an optical input terminal and an optical output terminal.
[0049] The switching power supply 50 is used to output a first power supply and a second power supply that are independently isolated from each other. The first power supply powers the MCU 10 and the optocoupler input terminal, while the second power supply powers the driver chip 20, the electronic expansion valve 30, and the optocoupler output terminal. The voltage values of the first power supply and the second power supply can be equal, for example, both being 12V. Figure 3 In the middle, the dashed line represents the power supply line.
[0050] This embodiment sets up an optocoupler isolation circuit between the MCU and the driver chip, which isolates the control signal output by the MCU from the drive signal output by the driver chip. Furthermore, the MCU and optocoupler input terminals are powered by mutually isolated power supplies from the driver chip, electronic expansion valve, and optocoupler output terminals, avoiding crosstalk between power supplies. This achieves isolation between the control and drive terminals of the electronic expansion valve in terms of control and power supply, reducing mutual interference between the control and drive circuits. Interference in the electronic expansion valve drive circuit cannot be transmitted to the MCU control terminal, reducing electromagnetic interference caused by the electronic expansion valve coil. This prevents the switching noise generated when the electronic expansion valve operates from interfering with the MCU and causing control malfunctions, and also prevents electromagnetic interference from the switching noise generated when the electronic expansion valve operates on surrounding electrical equipment. This ensures the stability of the controller and surrounding electrical equipment, solving the problem of interference caused by the switching noise of the electronic expansion valve to the controller and surrounding electrical equipment.
[0051] The optocoupler isolation circuit 40 includes at least one optocoupler, the number of which is equal to the number of control signals output by the MCU 10. For example, for an electronic expansion valve driven by a four-phase eight-step stepper motor, the MCU outputs four control signals.
[0052] The optical input terminals of the at least one optocoupler are respectively connected to at least one control signal output terminal of the MCU 10. The optical output terminals of the at least one optocoupler are respectively connected to at least one control signal input terminal of the driver chip 20.
[0053] In this embodiment, the number of optocouplers is set to be equal to the number of control signal outputs from the MCU. The input terminals of the optocouplers are connected to the control signal output terminals of the MCU, and the output terminals of the optocouplers are connected to the control signal input terminals of the driver chip. This realizes the connection of the optocoupler isolation circuit between the MCU and the driver chip, ensuring that the control signals and drive signals are isolated.
[0054] An optocoupler typically consists of a light emitter and a light receiver. The light emitter can be a light-emitting diode (LED), and the light receiver can be a photosensitive device, such as a phototransistor. The light emitter serves as the input terminal of the optocoupler, and the light receiver serves as the output terminal.
[0055] like Figure 4 As shown, the positive terminal of the optocoupler input is connected to the first power supply through a current-limiting resistor R; the negative terminal of the optocoupler input is connected to the control signal output terminal of the MCU 10; the positive terminal of the optocoupler input is also connected to the negative terminal of the optocoupler input through a filter capacitor C. Figure 4 In the middle, the dashed line represents the power supply line.
[0056] This embodiment prevents damage to the LED by setting a current-limiting resistor at the input of the optocoupler; and filters high-frequency noise and effectively blocks interference signals by setting a filter capacitor at the input of the optocoupler, ensuring a purer and more stable input signal for the optocoupler.
[0057] like Figure 4 As shown, the collector of the optocoupler output terminal is connected to the control signal input terminal of the driver chip 20; the collector of the optocoupler output terminal is also connected to the second power supply through a pull-up resistor R0; the emitter of the optocoupler output terminal is grounded.
[0058] This embodiment uses a pull-up resistor at the output of the optocoupler to clamp the signal at a high level, ensuring signal stability and also limiting current.
[0059] In an optional embodiment, the switching power supply 50 includes a transformer, the transformer including at least two secondary coils, the transformer outputting the first power supply and the second power supply through different secondary coils.
[0060] This embodiment outputs two independent and isolated power supplies through different secondary coils, which facilitates the isolation between the control end and the drive end of the electronic expansion valve, and the implementation method is simple.
[0061] In an optional embodiment, the switching power supply 50 further includes a Y capacitor, one end of which is connected to the primary bus of the transformer, and the other end of which is connected to the ground terminal of the secondary coil of the transformer used to output the second power supply, so that interference from the secondary side flows back to the primary side, forming an interference flow loop. See details for further information. Figure 5 .
[0062] This embodiment, by setting a Y capacitor, can provide an internal flow path for interference, preventing interference from flowing out of the line and affecting surrounding electrical equipment.
[0063] If the electronic expansion valve operates for an extended period, it will cause the coil temperature to rise, increasing internal resistance, power loss, and efficiency to decrease. This leads to an increase in coil current, which exacerbates the switching noise of the electronic expansion valve and thus intensifies electromagnetic interference. In an optional embodiment, the MCU 10 includes:
[0064] A timing module is used to record the continuous operating time of the electronic expansion valve;
[0065] The control module is used to stop outputting control signals to stop the electronic expansion valve from operating when the continuous operation time reaches a first preset time, and to continue outputting control signals to stop the electronic expansion valve from operating after a second preset time, and so on, until the electronic expansion valve reaches the target number of steps.
[0066] The duration of continuous operation can be obtained by monitoring the action of the electronic expansion valve, or it can be considered as the duration for which the MCU continuously sends control signals. The first preset time and the second preset time can be set according to the actual situation.
[0067] This embodiment, by intermittently controlling the electronic expansion valve, can prevent the problem of increased switching noise caused by prolonged operation of the electronic expansion valve, thereby exacerbating electromagnetic interference.
[0068] Optionally, the first preset time is longer than the second preset time. For example, the first preset time is 10 seconds and the second preset time is 1 second. In this embodiment, the continuous operating time of the electronic expansion valve is longer than the shut-off time, which enables intermittent control while ensuring the normal operation of the electronic expansion valve and preventing the increased switching noise caused by prolonged operation of the electronic expansion valve.
[0069] The electronic expansion valve control circuit described above will be illustrated below with a specific example. However, it is worth noting that this specific embodiment is only for better illustration of this application and does not constitute an undue limitation of this application. The same or corresponding terminology used in the above embodiments will not be repeated in this embodiment.
[0070] like Figure 5As shown, L1 is the high-frequency transformer of the switching power supply, CL is the bus capacitor, U7 is the PWM controller, and U6 is the optocoupler bridging high and low voltage. These components, along with diodes D1, D2, D3, and capacitors C1, C2, C3, C4, and C10, constitute the switching power supply. The 220V AC mains power is rectified to 310V DC. The switching power supply converts this 310V DC to the required power (e.g., 12V_A and 12V_B) to power the MCU, optocoupler isolation circuit, driver chip U5, and electronic expansion valve EXV. PWM_CTR controls the conduction of the primary coil of the transformer, thereby transferring the voltage from the primary coil to the secondary winding. Diodes D1, D2, and D3 are rectifier diodes, conducting in one direction, allowing capacitors C1, C2, C3, C4, and C10 to charge and form a voltage. Unconnected terminals in the secondary coil of transformer L1 can output the required power for other circuits, such as an 18V output. Figure 5 In the diagram, cross intersections with solid dots indicate that they are connected, while T-shaped intersections are connected by default.
[0071] Taking an air conditioner as an example, the outdoor unit sends the target number of steps required by the electronic expansion valve to the MCU. The MCU implements the control cycle of the electronic expansion valve. U5 is the driver chip for the electronic expansion valve, which implements the driving function of the electronic expansion valve. EXV1, EXV2, EXV3, and EXV4 are the control signals for the electronic expansion valve. The MCU outputs control signals according to the target number of steps sent by the outdoor unit to make the electronic expansion valve perform forward and reverse rotation. The coil of the electronic expansion valve is divided into two parts, each part has two windings, for a total of four windings. Each winding corresponds to one phase, that is, four phases. The common terminal of the windings is connected to the power supply.
[0072] In this embodiment, an optocoupler isolation circuit (including optocouplers U1 to U4) is set between the MCU and the driver chip U5. The MCU, optocouplers U1 to U4, driver chip U5, and electronic expansion valve EXV are powered by a switching power supply. The switching power supply outputs two independent and isolated power supplies through different secondary coils, namely power supplies 12V_A and 12V_B. Power supply 12V_A supplies power to driver chip U5, the output of the optocouplers, and the electronic expansion valve EXV, while power supply 12V_B supplies power to the MCU and the input of the optocouplers. Because the two power supplies belong to different coils of the high-frequency transformer, they are isolated on the circuit, thus reducing mutual interference between the control circuit and the drive circuit and preventing interference to the MCU caused by the operation of the electronic expansion valve, which could lead to control malfunctions.
[0073] Control isolation section: Optocouplers U1, U2, U3, and U4 provide isolation in the control circuit, and the input and output sides of the optocouplers are powered by isolated power supplies. This prevents interference in the electronic expansion valve drive circuit from being transmitted to the MCU control terminal, avoiding interference from the switching noise generated when the electronic expansion valve operates, which could lead to control malfunctions. Resistors R1, R2, R3, and R4 are current-limiting resistors at the optocoupler input terminals, capacitors C5, C6, C7, and C8 are filter capacitors at the optocoupler input terminals, and resistors R5, R6, R7, and R8 are pull-up resistors at the optocoupler output terminals.
[0074] Power isolation section: The switching power supply outputs two independent and isolated power supplies, namely power supplies 12V_A and 12V_B, through different secondary coils. The lines between the power supplies are isolated from each other, avoiding crosstalk. Power supply VCC_AUX powers the PWM controller U7 through the output of optocoupler U6. The input of optocoupler U6, together with the power supply 12V_B output from the switching power supply and the voltage reference Vref, forms a voltage sample, resulting in a stable power supply 12V_B. This stable power supply 12V_B is then converted by power converter U8 (e.g., DC-DC topology) to power the MCU. This stable power supply 12V_B also powers the input of the optocoupler. Power supply 12V_A powers the driver chip U5, the optocoupler output, and the electronic expansion valve EXV.
[0075] Drive Section: If the MCU's control signal EXV1 output is low, the LED at the input of optocoupler U1 conducts, which in turn conducts at the output of optocoupler U1. The input of driver chip U5 is low, and the corresponding I / O output of driver chip U5 is high, causing the corresponding electronic expansion valve winding to de-conduct. If the MCU's control signal EXV1 output is high, the LED at the input of optocoupler U1 de-conducts, which in turn de-conducts at the output of optocoupler U1. The input of driver chip U5 is high, and the corresponding I / O output of driver chip U5 is low, causing the corresponding electronic expansion valve winding to conduct. Other control signals follow a similar pattern, thus controlling the opening degree of the electronic expansion valve.
[0076] The electronic expansion valve control circuit described in this embodiment can achieve isolation between the control end and the drive end of the electronic expansion valve in terms of control and power supply, reducing the interference caused by the switching noise generated by the electronic expansion valve coil to the controller and surrounding electrical equipment, ensuring the stability of the controller and surrounding electrical equipment operation, and solving the problem of interference caused by the switching noise of the electronic expansion valve to the controller and surrounding electrical equipment in the prior art. Furthermore, intermittent control of the electronic expansion valve can prevent the switching noise from aggravating due to prolonged operation, thus preventing the exacerbation of electromagnetic interference.
[0077] Example 2
[0078] This embodiment provides an electrical device, including: an electronic expansion valve and the electronic expansion valve control circuit described in the above embodiment.
[0079] The electrical equipment in this embodiment can be an air conditioner or a refrigerator, etc.
[0080] This embodiment sets up an optocoupler isolation circuit between the MCU and the driver chip, which isolates the control signal output by the MCU from the drive signal output by the driver chip. Furthermore, the MCU and optocoupler input terminals are powered by mutually isolated power supplies from the driver chip, electronic expansion valve, and optocoupler output terminals, avoiding crosstalk between power supplies. This achieves isolation between the control and drive terminals of the electronic expansion valve in terms of control and power supply, reducing mutual interference between the control and drive circuits. Interference in the electronic expansion valve drive circuit cannot be transmitted to the MCU control terminal, reducing electromagnetic interference caused by the electronic expansion valve coil. This prevents the switching noise generated when the electronic expansion valve operates from interfering with the MCU and causing control malfunctions, and also prevents electromagnetic interference from the switching noise generated when the electronic expansion valve operates on surrounding electrical equipment. This ensures the stability of the controller and surrounding electrical equipment, solving the problem of interference caused by the switching noise of the electronic expansion valve to the controller and surrounding electrical equipment.
[0081] Example 3
[0082] This embodiment provides an electronic expansion valve control method, which is applied to the electronic expansion valve control circuit described in the above embodiment. Figure 6 This is a flowchart of the electronic expansion valve control method provided in this embodiment of the utility model, such as... Figure 6 As shown, the method includes the following steps:
[0083] S601 records the continuous operating time of the electronic expansion valve.
[0084] S602, when the continuous operation time reaches a first preset time, the control signal is stopped to stop the electronic expansion valve from operating. After a second preset time, the control signal is continued to be output to make the electronic expansion valve continue to operate. This cycle is repeated until the electronic expansion valve reaches the target number of steps.
[0085] The duration of continuous operation can be obtained by monitoring the action of the electronic expansion valve, or it can be considered as the duration for which the MCU continuously sends control signals. The first preset time and the second preset time can be set according to the actual situation.
[0086] This embodiment, by intermittently controlling the electronic expansion valve, can prevent the problem of increased switching noise caused by prolonged operation of the electronic expansion valve, thereby exacerbating electromagnetic interference.
[0087] Optionally, the first preset time is longer than the second preset time. For example, the first preset time is 10 seconds and the second preset time is 1 second. In this embodiment, the continuous operating time of the electronic expansion valve is longer than the shut-off time, which enables intermittent control while ensuring the normal operation of the electronic expansion valve and preventing the increased switching noise caused by prolonged operation of the electronic expansion valve.
[0088] The above electronic expansion valve control method will be illustrated below with a specific example. This specific example is only for better illustration of this application and does not constitute an undue limitation on this application.
[0089] like Figure 7 As shown, the intermittent control method for the electronic expansion valve includes the following steps:
[0090] S701, power on.
[0091] S702 resets the electronic expansion valve. Specifically, the MCU sends control signals EXV4, EXV3, EXV2, and EXV1 in reverse phase sequence until the electronic expansion valve rotates to its reverse limit position, at which point the electronic expansion valve is completely closed, thus achieving valve closure and reset. The electronic expansion valve is reset each time the device is powered on to ensure it is completely closed, and the step count at this position is set to 0, serving as the reference for the adjustment step count.
[0092] During equipment operation, the S703 MCU records the current step count of the electronic expansion valve and receives the target step count sent by the outdoor unit based on the cooling / heating requirements.
[0093] S704 compares the current number of steps with the target number of steps.
[0094] S705 If the current step number is greater than the target step number, it means that the opening of the electronic expansion valve needs to be reduced. Calculate the difference between the current step number and the target step number, and use this difference as the number of rotations R1. The MCU sends control signals EXV4, EXV3, EXV2, and EXV1 in reverse phase sequence to make the electronic expansion valve rotate R1 steps.
[0095] S706 If the current step number is less than the target step number, it means that the opening of the electronic expansion valve needs to be increased. Calculate the difference between the target step number and the current step number, and take this difference as the number of steps R2 to be rotated. The MCU sends control signals EXV1, EXV2, EXV3, and EXV4 in the positive phase sequence to make the electronic expansion valve rotate R2 steps.
[0096] S707 If the current step number equals the target step number, it means that the opening of the electronic expansion valve does not need to be adjusted. The MCU does not output a control signal and returns to S703.
[0097] S708, record the continuous operating time t of the electronic expansion valve. When t reaches t1 (i.e., the first preset time mentioned above), control the electronic expansion valve to stop operating. When the stopping time reaches t2 (i.e., the second preset time mentioned above), control the electronic expansion valve to continue operating. This cycle continues until the R1 or R2 steps required for the electronic expansion valve to rotate reach the target number of steps. t1 / t2 > 1.
[0098] The operation of the electronic expansion valve refers to the MCU outputting control signals (including positive and negative timing signals), while the MCU stopping the output of control signals means that the electronic expansion valve is shut down.
[0099] This embodiment achieves accurate control of the electronic expansion valve by intermittent control, preventing the problem of increased power loss and aggravated electromagnetic interference caused by prolonged operation of the electronic expansion valve.
[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.
Claims
1. An electronic expansion valve control circuit, characterized in that, include: The controller MCU is used to output control signals; A driver chip, connected to the electronic expansion valve, is used to drive the electronic expansion valve to operate according to the control signal; An optocoupler isolation circuit is connected between the MCU and the driver chip. The optocoupler isolation circuit includes an optocoupler input terminal and an optocoupler output terminal. A switching power supply is used to output a first power supply and a second power supply that are independently isolated from each other. The first power supply powers the MCU and the optocoupler input terminal, and the second power supply powers the driver chip, the electronic expansion valve and the optocoupler output terminal.
2. The electronic expansion valve control circuit according to claim 1, characterized in that, The optocoupler isolation circuit includes at least one optocoupler, the number of which is equal to the number of control signals output by the MCU; The optical input terminal of the at least one optocoupler is connected to at least one control signal output terminal of the MCU in a one-to-one correspondence. The output terminal of the at least one optocoupler is connected to at least one control signal input terminal of the driver chip in a one-to-one correspondence.
3. The electronic expansion valve control circuit according to claim 1, characterized in that, The positive terminal of the optocoupler input is connected to the first power supply through a current-limiting resistor; The negative terminal of the optocoupler input is connected to the control signal output terminal of the MCU; The positive terminal of the optocoupler input is also connected to the negative terminal of the optocoupler input via a filter capacitor.
4. The electronic expansion valve control circuit according to claim 1, characterized in that, The collector of the optocoupler output terminal is connected to the control signal input terminal of the driver chip; The collector of the optocoupler output terminal is also connected to the second power supply via a pull-up resistor; The emitter of the optocoupler output terminal is grounded.
5. The electronic expansion valve control circuit according to claim 1, characterized in that, The switching power supply includes a transformer, which includes at least two secondary coils, and the transformer outputs the first power supply and the second power supply through different secondary coils.
6. The electronic expansion valve control circuit according to claim 5, characterized in that, The switching power supply further includes a Y capacitor, one end of which is connected to the primary bus of the transformer, and the other end of which is connected to the ground terminal of the secondary coil of the transformer used to output the second power supply.
7. The electronic expansion valve control circuit according to claim 1, characterized in that, The MCU includes: A timing module is used to record the continuous operating time of the electronic expansion valve; The control module is used to stop outputting control signals to stop the electronic expansion valve from operating when the continuous operation time reaches a first preset time, and to continue outputting control signals to stop the electronic expansion valve from operating after a second preset time, and so on, until the electronic expansion valve reaches the target number of steps.
8. The electronic expansion valve control circuit according to claim 7, characterized in that, The first preset time is greater than the second preset time.
9. An electrical appliance, characterized in that, include: An electronic expansion valve and an electronic expansion valve control circuit according to any one of claims 1 to 8.