Fan drive circuit and refrigerator

Abstract

The embodiment of the application provides a fan driving circuit and a refrigerator, the fan driving circuit comprises: a switching circuit, an input end of the switching circuit is used for connecting a control signal, the switching circuit is used for generating a driving voltage signal according to the control signal; an isolation circuit, an input end of the isolation circuit is connected with an output end of the switching circuit, and an output end of the isolation circuit is used for connecting a fan, and the isolation circuit is used for carrying out isolation processing on the driving voltage signal, so as to drive the fan by using the driving voltage signal after the isolation processing. By setting the isolation circuit to isolate the fan from the power supply, the influence of the reverse electromotive force generated when the fan operates on the power supply can be reduced, and then the influence of the power supply ripple on other circuit components can be reduced, and then the use experience of the user can be improved.

Description

Technical Field

[0001] This application belongs to the field of refrigerator technology, and particularly relates to a fan drive circuit and a refrigerator. Background Technology

[0002] The basic task of a drive circuit is to convert the signals from information electronic circuits into signals that can be applied between the control terminal and the common terminal of the electronic device, according to the requirements of its control objectives, so as to turn the device on or off. For semi-controlled devices, only an on control signal needs to be provided, while for fully controlled devices, both on and off control signals need to be provided to ensure that the device can reliably turn on or off as required.

[0003] However, in existing circuits with inductive loads, such as fan drive circuits, the back electromotive force generated by the inductive load during operation can easily affect the power supply, thereby causing power supply ripple to affect other circuit components. Utility Model Content

[0004] This application provides a fan drive circuit and electronic device that can reduce the impact of the back electromotive force generated during the operation of inductive loads on the power supply, thereby reducing the impact of power supply ripple on other circuit components.

[0005] In a first aspect, embodiments of this application provide a wind turbine drive circuit, including:

[0006] A switching circuit, the input of which is used to receive a control signal, and the switching circuit is used to generate a drive voltage signal according to the control signal;

[0007] An isolation circuit is provided, the input of which is connected to the output of the switching circuit, and the output of which is used to connect to a fan. The isolation circuit is used to isolate the drive voltage signal so that the fan can be driven by the isolated drive voltage signal.

[0008] Optionally, the isolation circuit includes a voltage follower circuit, one input terminal of which is connected to the output terminal of the switching circuit, and the other input terminal of which is connected to its output terminal. The output terminal of the voltage follower circuit is used to connect to the fan, and the voltage follower circuit is used to keep the output voltage synchronized with the input drive voltage signal.

[0009] Optionally, the voltage follower circuit includes:

[0010] An operational amplifier, wherein the non-inverting input terminal of the operational amplifier is connected to the output terminal of the switching circuit, the inverting input terminal of the operational amplifier is connected to the output terminal of the operational amplifier, and the output terminal of the operational amplifier is used to connect to the fan;

[0011] The first resistor is connected between the inverting input terminal and the output terminal of the operational amplifier.

[0012] Optionally, the voltage follower circuit further includes:

[0013] The first current-limiting resistor has one end connected to the non-inverting input terminal of the operational amplifier and the other end connected to the output terminal of the switching circuit.

[0014] The second current-limiting resistor has one end connected to the output terminal of the operational amplifier and the other end used to connect to the fan.

[0015] Optionally, the wind turbine drive circuit further includes:

[0016] A startup capacitor is connected in parallel between the output of the isolation circuit and ground.

[0017] Optionally, the startup capacitor includes:

[0018] The first capacitor has one end connected to the output terminal of the isolation circuit and the other end grounded.

[0019] The second capacitor is connected in parallel with the first capacitor, and the capacitance value of the second capacitor is different from that of the first capacitor.

[0020] Optionally, the switching circuit includes:

[0021] The first driving sub-circuit has an input terminal for receiving control signals, a power supply terminal for receiving a first power supply, and an output terminal for grounding.

[0022] The second driving sub-circuit has its input terminal connected to the power supply terminal of the first driving sub-circuit, and its power supply terminal is used to connect to a second power supply. The voltage of the second power supply is greater than the voltage of the first power supply, and its output terminal is grounded.

[0023] Optionally, the first driving sub-circuit includes:

[0024] The first transistor has its base connected to a control signal through a second resistor, its collector connected to the first power supply through a third resistor, and its emitter grounded.

[0025] The fourth resistor has one end connected to the base of the first transistor and the other end grounded.

[0026] Optionally, the second driving sub-circuit includes:

[0027] The base of the second transistor is connected to the collector of the first transistor through a fifth resistor, the collector of the second transistor is connected to the second power supply through a sixth resistor, and the emitter is grounded.

[0028] The seventh resistor has one end connected to the base of the second transistor and the other end grounded.

[0029] Secondly, embodiments of this application also provide a refrigerator, including the fan drive circuit as described in any of the preceding claims.

[0030] In the fan drive circuit and refrigerator of this application embodiment, by setting an isolation circuit to isolate the fan from the power supply, the influence of the back electromotive force generated during the operation of the fan on the power supply can be reduced, thereby reducing the influence of power supply ripple on other circuit components and improving the user experience. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings. In the following description, the same reference numerals denote the same parts.

[0033] Figure 1 A structural block diagram of a wind turbine drive circuit provided in an embodiment of this application.

[0034] Figure 2 A circuit diagram of a wind turbine drive circuit provided in an embodiment of this application. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0036] Common driving methods include direct drive, push-pull drive, and isolated drive. Direct drive circuits consist of individual electronic components (such as diodes, transistors, MOSFETs, resistors, and capacitors) connected together. They lack electrical isolation and are often used in simple, low-power applications. In complex digital power systems, direct drive circuits have been gradually phased out due to low integration and high failure rates. Push-pull drives can be used when the power IC's driving capability is insufficient. This type of drive circuit improves current delivery and quickly completes the charging process of the gate input capacitor. This topology increases the turn-on time but reduces the turn-off time, allowing the switching transistor to turn on quickly and avoiding high-frequency oscillations on the rising edge. Isolated drive circuits include isolation devices, commonly including optocoupler drives, transformer drives, and isolation capacitor drives. Optocoupler drives are simple, reliable, and have good switching performance. Transformer drives not only provide driving but also serve as voltage isolation and impedance matching.

[0037] However, in existing circuits driving inductive loads, such as fan drive circuits, the back electromotive force generated by the inductive load during operation can easily affect the power supply, causing power supply ripple to impact other circuit components. Therefore, how to achieve isolation between the power supply and the inductive load in a simple structure has become an urgent problem to be solved.

[0038] To reduce the impact of the back electromotive force generated by inductive loads such as fans during operation on the power supply, embodiments of this application provide a fan drive circuit and a refrigerator, which will be described below with reference to the accompanying drawings.

[0039] Please see Figure 1 , Figure 1 This is a structural block diagram of a fan drive circuit provided in an embodiment of this application. The fan drive circuit 100 is applied to a refrigerator, which may include a main control board or MCU. The main control board is used to control the overall operation of the refrigerator, and the fan drive circuit 100 is used to receive control signals from the main control board to drive the fan. Of course, the drive circuit of this application is not only applicable to fans, but can also be applied to other inductive loads such as compressors; and the electronic equipment is not limited to refrigerators, but can also be air conditioners, washing machines, etc. This application uses a refrigerator fan drive circuit as an example for illustration, and should not be construed as a limitation on electronic equipment and inductive loads.

[0040] For example, the fan drive circuit 100 includes a switching circuit 110 and an isolation circuit 120.

[0041] The input terminal of the switching circuit 110 is used to receive the control signal, which is the signal issued by the main control board to control the operation of the fan. The switching circuit 110 is used to generate a drive voltage signal according to the control signal.

[0042] The isolation circuit 120 is used to isolate the power supply from the load, thereby reducing the impact of the load on the power supply and improving the stability of system operation. The input terminal of the isolation circuit 120 is connected to the output terminal of the switching circuit 110, and the output terminal of the isolation circuit 120 is used to connect to the fan. The isolation circuit 120 is used to isolate the drive voltage signal so that the isolated drive voltage signal can be used to drive the fan.

[0043] In the fan drive circuit 100 provided in this application embodiment, the fan is isolated from the power supply by setting an isolation circuit 120, which can reduce the impact of the reverse electromotive force generated during the operation of the fan on the power supply, thereby reducing the impact of power supply ripple on other circuit components and improving the user experience.

[0044] For example, the isolation circuit 120 may include a voltage follower circuit. One input of the voltage follower circuit is connected to the output of the switching circuit 110, and the other input is connected to its output. The output of the voltage follower circuit is used to connect to a fan, and the voltage follower circuit is used to keep the output voltage synchronized with the input drive voltage signal. That is to say, when driving a load, the power supply does not directly supply power to the load, but the voltage follower circuit drives it, which can reduce system power supply interference and improve system circuit stability.

[0045] For example, please refer to Figure 1 And see Figure 2 As shown, Figure 2 This is a circuit diagram of a wind turbine drive circuit provided in an embodiment of this application. The voltage follower circuit includes an operational amplifier U1, a first resistor R1, a first current-limiting resistor R11, and a second current-limiting resistor R12.

[0046] The non-inverting input of operational amplifier U1 is connected to the output of switching circuit 110, the inverting input of operational amplifier U1 is connected to the output of operational amplifier U1, and the output of operational amplifier U1 is used to connect to the fan.

[0047] The first resistor R1 is connected between the inverting input terminal and the output terminal of the operational amplifier U1. The first resistor R1 is a current-limiting resistor for the feedback signal.

[0048] One end of the first current-limiting resistor R11 is connected to the non-inverting input terminal of the operational amplifier U1, and the other end of the first current-limiting resistor R11 is connected to the output terminal of the switching circuit 110. The first current-limiting resistor R11 is an input current-limiting resistor used for circuit protection.

[0049] One end of the second current-limiting resistor R12 is connected to the output terminal of the operational amplifier U1, and the other end of the second current-limiting circuit R12 is used to connect to the fan. The second current-limiting resistor R12 is the output current-limiting resistor to prevent the output port from being incorrectly grounded, which would cause the operational amplifier output port current to be too large and burn out the chip.

[0050] In this embodiment, the operational amplifier U1, the first resistor R1, the first current limiting current R11, and the second current limiting resistor R12 constitute a voltage follower circuit. Essentially, it is an integrated operational amplifier with a gain of 1. It also has a negative feedback function, which can automatically adjust the difference between the output voltage and the input voltage to keep the output voltage and the input voltage synchronized.

[0051] To prevent large voltage fluctuations after load startup, this embodiment of the application also connects a startup capacitor to the output terminal of the isolation circuit 120. For example, the fan drive circuit 100 further includes a startup capacitor connected in parallel between the output terminal of the isolation circuit 120 and ground (GND).

[0052] For example, the starting capacitor may include a first capacitor C1 and a second capacitor C2. One end of the first capacitor C1 is connected to the output terminal of the isolation circuit 120, and the other end of the first capacitor C1 is grounded (GND). The second capacitor C2 is connected in parallel with the first capacitor C1. The capacitance values ​​of the second capacitor C2 and the first capacitor C1 are different, for example, the capacitance value of the second capacitor C2 is greater than that of the first capacitor C1. Furthermore, the second capacitor C2 can be an electrolytic capacitor, and the first capacitor C1 is a general-purpose capacitor. By using two different types of capacitors in combination, such as the first capacitor C1 having a smaller capacitance to maintain the phase difference and power factor during normal operation, and the second capacitor C2 having a larger capacitance to provide instantaneous high-power starting torque, the combination of the two starting capacitors can achieve a smooth start-up of the system and prevent the problem of large voltage fluctuations after the load starts.

[0053] The switching circuit 110 can be implemented using a two-stage driving circuit. For example, the switching circuit 110 includes a first driving sub-circuit and a second driving sub-circuit.

[0054] The input terminal of the first driving sub-circuit is used to receive control signals, the power supply terminal of the first driving sub-circuit is used to receive the first power supply, and the output terminal of the first driving sub-circuit is grounded.

[0055] For example, the first driving sub-circuit may include a first transistor Q1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The base of the first transistor Q1 is connected to a control signal through the second resistor R2, the collector of the first transistor Q1 is connected to a first power supply through the third resistor R3, and the emitter of the first transistor Q1 is grounded to GND. One end of the fourth resistor R4 is connected to the base of the first transistor Q1, and the other end of the fourth resistor R4 is grounded to GND.

[0056] The input terminal of the second driving sub-circuit is connected to the power supply terminal of the first driving sub-circuit. The power supply terminal of the second driving sub-circuit is used to connect to a second power supply, the voltage of which is greater than that of the first power supply. The output terminal of the second driving sub-circuit is grounded. For example, the voltage of the first power supply can be 5V, and the voltage of the second power supply can be 12V.

[0057] For example, the second driver sub-circuit includes a second transistor Q2, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. The base of the second transistor Q2 is connected to the collector of the first transistor Q1 through the fifth resistor R5, the collector of the second transistor Q2 is connected to a second power supply through the sixth resistor R6, and the emitter of the second transistor Q2 is grounded to GND. One end of the seventh resistor R7 is connected to the base of the second transistor Q2, and the other end of the seventh resistor R7 is grounded to GND.

[0058] Understandably, the two transistors form a two-stage drive switching circuit. Since the main control board (MCU) operates at 5V and outputs a 5V signal, to prevent the 12V voltage from directly flowing into the MCU and damaging it due to transistor breakdown, the base of the first transistor Q1 is connected to the MCU's I / O port via the second resistor R2. Simultaneously, a pull-down resistor R4 is connected to the base of the first transistor Q1. The base of the second transistor Q2 is connected to the collector of the first transistor Q1 via the fifth resistor R5. The main chip sends a high-level or low-level signal to control the conduction or cutoff of the first transistor Q1, changing the voltage at the collector of the first transistor Q1, and thus controlling the conduction or cutoff of the second transistor Q2.

[0059] The working principle of the fan drive circuit 100 is as follows: When the main control board, i.e. the MCU, outputs a high level at the IO port, the base voltage of the first transistor Q1 is 5V. At this time, the first transistor Q1 is turned on, that is, the collector and emitter are turned on, and the emitter is grounded. Therefore, the voltage at the first transistor Q1 is pulled low. The base voltage of the second transistor Q2 is low, so Q2 is cut off, meaning its collector and emitter are disconnected. The collector of Q2 is connected to the second 12V power supply through the pull-up resistor (R6), resulting in a collector voltage of 12V. This voltage is then input to the operational amplifier U1 through the current-limiting resistor (R11). Based on the virtual short and virtual open characteristics of the operational amplifier circuit, the formulas for calculating the non-inverting input voltage V1, the inverting input voltage V3, and the output voltage V4 are: V1 = V3 = 12V, (12V - V1) / (R6 + R11) = (V3 - V4) / (R1 + R12) = 0. Therefore, the output voltage is 12V.

[0060] When the circuit is off, and the I / O port of the main control board (i.e., the MCU) outputs a low level, the base voltage of the first transistor Q1 is 0V. At this time, the first transistor Q1 is cut off, meaning the collector and emitter are disconnected. The collector is connected to a pull-up resistor, i.e., the third resistor R3, so the voltage at the collector of the first transistor Q1 is pulled high. Consequently, the base voltage of the second transistor Q2 is high, and the second transistor Q2 is turned on, meaning the collector and emitter are connected. The emitter is grounded, and the voltage at the second transistor Q2 is pulled low. This voltage is input to the integrated operational amplifier U1 through the current-limiting resistor, i.e., the first current-limiting resistor R11. Based on the virtual short and virtual open characteristics of the integrated operational amplifier circuit, the calculation formulas for the non-inverting input voltage V1, the inverting input voltage V3, and the output voltage V4 of the operational amplifier are: V1 = V3 = 0V, (0V - V1) / R11 = (V3 - V4) / (R1 + R12) = 0. That is, the output voltage is 0V.

[0061] This ensures that the output voltage and input voltage remain consistent. The front-end switching circuit 110 is controlled by two transistors, enabling fast switching. The rear-end integrated operational amplifier chip isolates the load. This embodiment optimizes the traditional transistor-driven principle. The voltage follower circuit composed of integrated operational amplifiers has isolation capabilities, isolating the impact of the fan load during startup, operation, and shutdown on the drive circuit, thereby reducing the power supply ripple of the system circuit.

[0062] The fan drive circuit 100 provided in this application embodiment is optimized based on the traditional load drive circuit by adding a voltage follower drive. When driving the load, the power supply does not directly supply power to the load, but the voltage follower drives it, which can reduce interference to the system power supply and improve the stability of the system circuit.

[0063] This application also provides a refrigerator, including a fan drive circuit as described above. Since the refrigerator uses the above-described fan drive circuit, it has all the beneficial effects of all the above embodiments.

[0064] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0065] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features.

[0066] The fan drive circuit and refrigerator provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A fan drive circuit, characterized by comprising: include: A switching circuit, the input of which is used to receive a control signal, and the switching circuit is used to generate a drive voltage signal according to the control signal; An isolation circuit is provided, the input of which is connected to the output of the switching circuit, and the output of which is used to connect to a fan. The isolation circuit is used to isolate the drive voltage signal so that the fan can be driven by the isolated drive voltage signal.

2. The fan drive circuit of claim 1, wherein, The isolation circuit includes a voltage follower circuit. One input terminal of the voltage follower circuit is connected to the output terminal of the switching circuit, and the other input terminal of the voltage follower circuit is connected to its output terminal. The output terminal of the voltage follower circuit is used to connect to the fan. The voltage follower circuit is used to keep the output voltage synchronized with the input drive voltage signal.

3. The fan drive circuit according to claim 2, characterized in that, The voltage follower circuit includes: An operational amplifier, wherein the non-inverting input terminal of the operational amplifier is connected to the output terminal of the switching circuit, the inverting input terminal of the operational amplifier is connected to the output terminal of the operational amplifier, and the output terminal of the operational amplifier is used to connect to the fan; The first resistor is connected between the inverting input terminal and the output terminal of the operational amplifier.

4. The fan drive circuit of claim 3, wherein, The voltage follower circuit also includes: The first current-limiting resistor has one end connected to the non-inverting input terminal of the operational amplifier and the other end connected to the output terminal of the switching circuit. The second current-limiting resistor has one end connected to the output terminal of the operational amplifier and the other end used to connect to the fan.

5. The fan drive circuit of claim 1, wherein, The fan drive circuit also includes: A startup capacitor is connected in parallel between the output of the isolation circuit and ground.

6. The fan drive circuit of claim 5, wherein, The startup capacitor includes: The first capacitor has one end connected to the output terminal of the isolation circuit and the other end grounded. The second capacitor is connected in parallel with the first capacitor, and the capacitance value of the second capacitor is different from that of the first capacitor.

7. The fan drive circuit of claim 1, wherein, The switching circuit includes: The first driving sub-circuit has an input terminal for receiving control signals, a power supply terminal for receiving a first power supply, and an output terminal for grounding. The second driving sub-circuit has its input terminal connected to the power supply terminal of the first driving sub-circuit, and its power supply terminal is used to connect to a second power supply. The voltage of the second power supply is greater than the voltage of the first power supply, and its output terminal is grounded.

8. The fan drive circuit of claim 7, wherein, The first driving sub-circuit includes: The first transistor has its base connected to a control signal through a second resistor, its collector connected to the first power supply through a third resistor, and its emitter grounded. The fourth resistor has one end connected to the base of the first transistor and the other end grounded.

9. The fan drive circuit of claim 8, wherein, The second driving sub-circuit includes: The base of the second transistor is connected to the collector of the first transistor through a fifth resistor, the collector of the second transistor is connected to the second power supply through a sixth resistor, and the emitter is grounded. The seventh resistor has one end connected to the base of the second transistor and the other end grounded.

10. A refrigerator characterized by comprising: Includes the wind turbine drive circuit as described in any one of claims 1 to 9.

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