Speed regulating circuit and fan system

Abstract

The application discloses a speed regulating circuit and a fan system. The speed regulating circuit comprises: a voltage conversion circuit comprising a power input end, a power output end and a feedback end, the power input end being used for being connected with a power supply, the power output end being used for being connected with a fan to provide a fan power supply voltage; the power output end is further connected with the ground through a first voltage dividing circuit, the feedback end is connected with a voltage dividing point of the first voltage dividing circuit, and the voltage conversion circuit is used for converting the power supply voltage into the fan power supply voltage based on a feedback voltage of the feedback end; a control circuit is used for generating a pulse modulation signal based on an ambient temperature; and a low-pass filter circuit, an input end of the low-pass filter circuit receiving the pulse modulation signal, and an output end of the low-pass filter circuit being connected with the voltage dividing point of the first voltage dividing circuit. Not only can the non-speed-regulating fan meet the demand of adapting to the ambient temperature, but also the speed of the fan can be reduced when the ambient temperature is low, so that the noise is reduced and the service life is prolonged.

Description

Technical Field

[0001] This application relates to the field of wind turbine control technology, and more specifically, to a speed control circuit and a wind turbine system. Background Technology

[0002] Fans, as a heat dissipation device, are widely used in energy systems. Currently, fans are mainly divided into two categories: variable-speed fans and non-variable-speed fans. Variable-speed fans have their own PWM signal for speed regulation, making them expensive. Considering cost factors, non-variable-speed fans are usually used in related technologies. However, non-variable-speed fans can only operate at a constant speed, which not only fails to meet the requirements for adapting to ambient temperature but also results in high noise and a short lifespan. Utility Model Content

[0003] This application provides a speed control circuit and a fan system. The various aspects involved in this application embodiment are described below.

[0004] In a first aspect, a speed control circuit is provided, comprising: a voltage conversion circuit, including a power input terminal, a power output terminal, and a feedback terminal, wherein the power input terminal is used to connect to a power source, the power output terminal is used to connect to a fan to provide a fan power supply voltage; the power output terminal is also grounded through a first voltage divider circuit, the feedback terminal is connected to the voltage division point of the first voltage divider circuit, and the voltage conversion circuit is used to convert the power supply voltage into the fan power supply voltage based on the feedback voltage of the feedback terminal; a control circuit, used to generate a pulse modulation signal based on the ambient temperature; and a low-pass filter circuit, wherein the input terminal of the low-pass filter circuit receives the pulse modulation signal, and the output terminal of the low-pass filter circuit is connected to the voltage division point of the first voltage divider circuit.

[0005] As one possible implementation, the low-pass filter circuit includes: a first filter circuit, including a first resistor and a first capacitor, wherein a first terminal of the first resistor receives the pulse modulation signal, a second terminal of the first resistor is connected to a first terminal of the first capacitor, and a second terminal of the second capacitor is grounded; and a second filter circuit, including a second resistor and a second capacitor, wherein a first terminal of the second resistor is connected to a second terminal of the first resistor, a second terminal of the second resistor is connected to a first terminal of the second capacitor, a second terminal of the second capacitor is grounded, and a second terminal of the second resistor is used to connect to the voltage divider point of the first voltage divider circuit.

[0006] As one possible implementation, the speed control circuit further includes a voltage follower circuit, which includes a positive input terminal, a negative input terminal, and an output terminal. The positive input terminal is connected to the output terminal of the low-pass filter circuit, the negative input terminal is connected to the output terminal of the voltage follower circuit, and the output terminal of the voltage follower circuit is also connected to the voltage divider point of the first voltage divider circuit.

[0007] As one possible implementation, the voltage follower circuit includes: a first operational amplifier, including a first positive input terminal, a first negative input terminal, and a first output terminal, wherein the first positive input terminal is connected to the output terminal of the low-pass filter circuit, and the first negative input terminal is connected to the first output terminal; and a second operational amplifier, including a second positive input terminal, a second negative input terminal, and a second output terminal, wherein the second positive input terminal is connected to the first output terminal, the second negative input terminal is connected to the second output terminal, and the second output terminal is also connected to the voltage divider point of the first voltage divider circuit.

[0008] As one possible implementation, the speed control circuit further includes a third resistor, one end of which is connected to the output terminal of the voltage follower circuit, and the other end of which is connected to the voltage divider point of the first voltage divider circuit.

[0009] In one possible implementation, the voltage conversion circuit includes a BUCK chip and an inductor, the control circuit includes a start / stop control terminal, the BUCK chip includes a pulse voltage output terminal and an enable terminal, the pulse voltage output terminal is connected to the power output terminal through the inductor, and the enable terminal is connected to the start / stop control terminal, so as to start or stop the BUCK chip by controlling the enable terminal.

[0010] As one possible implementation, the speed control circuit further includes: a first switching transistor, a first terminal of which is connected to the power supply terminal of the control circuit, a second terminal of which is connected to the enable terminal, and a control terminal of which is connected to the start / stop control terminal.

[0011] As one possible implementation, the speed control circuit further includes a temperature signal processing circuit, wherein the input terminal of the temperature signal processing circuit is used to receive an ambient temperature detection signal, and the output terminal of the temperature signal processing circuit is connected to the temperature detection interface of the control circuit.

[0012] As one possible implementation, the temperature signal processing circuit further includes: a pull-up resistor, the first end of which is connected to a power supply terminal, and the second end of which receives the ambient temperature detection signal; a current-limiting resistor, the first end of which is connected to the second end of the pull-up resistor, and the second end of which is connected to the temperature detection interface of the control circuit; and an interface protection circuit, the first end of which is connected to the second end of the pull-up resistor, and the second end of which is grounded.

[0013] In a second aspect, a fan system is provided, comprising: a fan and a speed control circuit as described in the first aspect.

[0014] The embodiments of this application add a control circuit and a low-pass filter circuit, which can realize the adjustment of feedback voltage based on ambient temperature to adjust the fan power supply voltage. This is beneficial for adjusting the fan speed by adjusting the fan power supply voltage based on ambient temperature when using low-cost non-speed-regulating fans. This not only allows non-speed-regulating fans to meet the requirements of adapting to ambient temperature, but also reduces the fan speed when the ambient temperature is low, thereby reducing noise and extending life. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the speed control circuit provided in one embodiment of this application.

[0016] Figure 2 This is a schematic diagram of the speed control circuit provided in another embodiment of this application.

[0017] Figure 3 This is a schematic diagram of the speed control circuit provided in another embodiment of this application.

[0018] Figure 4 This is a schematic diagram of the speed control circuit provided in another embodiment of this application. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application should fall within the scope of protection of the present application.

[0020] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0021] To facilitate understanding of this application, the following is combined with... Figure 1 The speed control circuit provided in the embodiments of this application will be described. For example... Figure 1 As shown, the speed control circuit 100 includes a voltage conversion circuit 110, a control circuit 120, and a low-pass filter circuit 130.

[0022] See details Figure 1 The voltage conversion circuit 110 may include a power input terminal, a power output terminal, and a feedback terminal FB. The power input terminal is used to connect to a power supply to receive the power supply voltage (i.e., the input voltage V).in The power output terminal is used to connect to the fan to provide a stable power supply voltage (i.e., output voltage V) for the fan. out Based on this supply voltage V out This supply voltage is used to drive the fan; in the following text, it will be referred to as the fan supply voltage V. out The power output terminal can also be grounded through the first voltage divider circuit 140, and the feedback terminal FB can be connected to the voltage divider point of the first voltage divider circuit 140 to use the detected voltage of the voltage divider point of the first voltage divider circuit 140 as the feedback voltage (or sampling voltage or detection voltage).

[0023] It is understandable that the voltage at the voltage divider point of the first voltage divider circuit 140 is the fan power supply voltage V. out Given that the first voltage divider circuit 140 is known, the voltage at the voltage divider point of the first voltage divider circuit 140 can be used to indicate the magnitude of the actual output fan power supply voltage.

[0024] The voltage at the voltage division point of the first voltage divider circuit 140 is related to the specific structure of the first voltage divider circuit 140. This application embodiment does not specifically limit the structure of the first voltage divider circuit 140; the first voltage divider circuit 140 can be composed of two or more resistors or other impedance components connected in series. As an example, such as... Figure 2 and Figure 4 As shown, the first voltage divider circuit 140 includes a fourth resistor R4 and a fifth resistor R5. One end of the fourth resistor R4 is connected to the power output terminal, and the other end of the fourth resistor R4 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is grounded. Optionally, the fifth resistor R5 can also be connected in parallel with the fifth capacitor C5.

[0025] The voltage conversion circuit 110 is used to convert the power supply voltage into a fan supply voltage based on the feedback voltage at the feedback terminal FB. Specifically, the voltage conversion circuit 110 compares the feedback voltage detected at the feedback terminal FB with a reference voltage inside the voltage conversion circuit 110, and controls the duty cycle of the switching transistor in the voltage conversion circuit 110 based on the comparison result, so that the power supply output terminal of the voltage conversion circuit 110 outputs a stable fan supply voltage. In other words, the fan supply voltage is determined by the feedback voltage at the feedback terminal FB and the reference voltage.

[0026] The control circuit 120 is connected to the feedback terminal FB through the low-pass filter circuit 130, and is used to adjust the feedback voltage of the feedback terminal FB based on the ambient temperature.

[0027] Specifically, the control circuit 120 is used to generate a pulse-width modulation (PWM) signal based on the ambient temperature. In this application, the control circuit 120 can be understood as a controller or a microcontroller. In some embodiments, the control circuit 120 may be a microcontroller unit (MCU).

[0028] In some embodiments, the control circuit 120 itself can detect the ambient temperature and generate a PWM signal based on the ambient temperature. For example, the control circuit 120 may integrate a temperature sensor or a thermistor or other device capable of detecting the ambient temperature.

[0029] In other embodiments, the control circuit 120 may generate a PWM signal based on a signal related to ambient temperature fed back by the temperature signal processing circuit 160.

[0030] Different ambient temperatures correspond to different PWM signals, and different PWM signals correspond to different duty cycles. A higher duty cycle indicates a higher proportion of high-level time within a cycle. This embodiment does not specifically limit the PWM signal generated by the control circuit 120 based on the ambient temperature. For example, the control circuit 120 can generate a first PWM signal based on a first ambient temperature and a second PWM signal based on a second ambient temperature. When the first ambient temperature is higher than the second ambient temperature, the duty cycle in the first PWM signal is lower than the duty cycle in the second PWM signal.

[0031] The low-pass filter circuit 130 may include an input terminal and an output terminal. The input terminal of the low-pass filter circuit 130 is connected to the control circuit 120 to receive the PWM signal. The output terminal of the low-pass filter circuit 130 is connected to the voltage division point of the first voltage divider circuit. The low-pass filter circuit 130 is used to convert the PWM signal output by the control circuit 120 into a voltage signal Vset, and outputs this voltage signal through the output terminal of the low-pass filter circuit 130. The voltage signal is used to change (or adjust) the magnitude of the feedback voltage detected by the feedback terminal FB. Based on this voltage signal, it can be understood as an adjustment voltage. This voltage signal may be referred to as Vset in the following text.

[0032] The feedback voltage at the feedback terminal FB, adjusted by the voltage signal Vset, is called the adjusted feedback voltage. This adjusted feedback voltage is used by the voltage conversion circuit to adjust the fan supply voltage based on a closed-loop feedback mechanism. In other words, the adjusted fan supply voltage is determined by the adjusted feedback voltage and the reference voltage of the voltage conversion circuit 110. Adjusting the fan supply voltage is equivalent to adjusting the fan's driving force, which in turn is equivalent to adjusting the fan's rotational speed.

[0033] This embodiment of the application, through a control circuit 120 and a low-pass filter circuit, enables the control circuit 120 to generate a PWM signal based on ambient temperature. The low-pass filter circuit then converts the PWM signal into a voltage signal used to adjust the feedback voltage at the feedback terminal FB, thereby adjusting the fan's power supply voltage based on the adjusted feedback voltage. This is advantageous in using low-cost, non-speed-regulating fans to adjust the fan's power supply voltage based on ambient temperature, thus regulating the fan's speed. This not only allows non-speed-regulating fans to adapt to ambient temperature requirements but also reduces fan speed at lower ambient temperatures, thereby reducing noise and extending lifespan.

[0034] This application does not specifically limit the type of the low-pass filter circuit 130. For example, the low-pass filter circuit 130 can be an RC low-pass filter circuit. As another example, the low-pass filter circuit 130 can be an LC low-pass filter circuit.

[0035] The RC low-pass filter circuit 130 can be a single-stage RC low-pass filter circuit or a multi-stage RC low-pass filter circuit.

[0036] As an example, such as Figure 2 and Figure 4 As shown, the low-pass filter circuit 130 is a two-stage RC low-pass filter circuit. See details. Figure 2 and Figure 4 The low-pass filter circuit 130 includes a first filter circuit and a second filter circuit. The first filter circuit includes a first resistor R1 and a first capacitor C1. The first end of the first resistor R1 is connected to the control circuit 120 to receive the PWM signal. The second end of the first resistor R1 is connected to the first end of the first capacitor C1, and the second end of the second capacitor C2 is grounded. The second filter circuit includes a second resistor R2 and a second capacitor C2. The first end of the second resistor R2 is connected to the second end of the first resistor R1, and the second end of the second resistor R2 is connected to the first end of the second capacitor C2. The second end of the second capacitor C2 is grounded. The second end of the second resistor R2 is the output terminal of the low-pass filter circuit 130. The second end of the second resistor R2 is also connected to the voltage divider point of the first voltage divider circuit and is used to output the voltage signal Vset. After the PWM signal is filtered by these two stages of RC low-pass filter circuits 130, it can be converted into a smooth DC signal (i.e., the voltage signal Vset). The larger the duty cycle D in the PWM signal, the larger the filtered voltage signal Vset; conversely, the smaller the duty cycle D, the smaller the filtered voltage signal Vset.

[0037] By setting the low-pass filter circuit 130 as a two-stage RC low-pass filter circuit, not only is the cost low, but the noise suppression capability is also improved, which can improve the smoothness and purity of the voltage signal Vset converted from the PWM signal.

[0038] In some implementations, such as Figure 3 and Figure 4 As shown, the speed control circuit 100 may further include a voltage follower circuit 150. The voltage follower circuit 150 is located between the low-pass filter circuit 130 and the voltage division point of the first voltage divider circuit. Specifically, the voltage follower circuit 150 includes a positive input terminal, a negative input terminal, and an output terminal. The positive input terminal of the voltage follower circuit 150 is connected to the output terminal of the low-pass filter circuit 130, the negative input terminal of the voltage follower circuit 150 is connected to the output terminal of the voltage follower circuit 150, and the output terminal of the voltage follower circuit 150 is also connected to the voltage division point of the first voltage divider circuit 140. The voltage signal at the output terminal of the voltage follower circuit 150 follows the change of the voltage signal Vset at the positive input terminal of the voltage follower circuit 150; in other words, the voltage follower circuit 150 is used to transmit the voltage signal Vset at the positive input terminal of the voltage follower circuit 150 through its output terminal. The voltage follower circuit 150 has the characteristics of high input impedance and low output impedance, which can effectively isolate the preceding and following circuits and enhance the signal carrying capacity.

[0039] By setting a voltage follower circuit 150 between the output of the low-pass filter circuit 130 and the voltage division point of the first voltage divider circuit 140, it is equivalent to isolating the low-pass filter circuit 130 and the voltage conversion circuit 110 while buffering the voltage signal Vset without gain, thus avoiding circuit interference from the control circuit 120 to the voltage conversion circuit 110.

[0040] The structure of the voltage follower circuit 150 in this application embodiment is not specifically limited. For example, the voltage follower circuit 150 can be an operational amplifier-based voltage follower circuit. Alternatively, the voltage follower circuit 150 can be a transistor-based voltage follower circuit. Furthermore, the voltage follower circuit 150 can also be a buffer chip with integrated voltage follower functionality.

[0041] Taking the voltage follower circuit 150 as an example, which is an operational amplifier-based voltage follower circuit, the voltage follower circuit 150 may include an operational amplifier, which includes a positive input terminal, a negative input terminal, and an output terminal. The positive input terminal of the operational amplifier is connected to the output terminal of the low-pass filter circuit 130, the negative 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 also connected to the voltage division point of the first voltage divider circuit.

[0042] In some embodiments, such as Figure 4As shown, the operational amplifier in the voltage follower circuit 150 can be a two-stage operational amplifier. Specifically, the voltage follower circuit 150 can include a first operational amplifier and a second operational amplifier. The first operational amplifier includes a first positive input terminal, a first negative input terminal, and a first output terminal. The first positive input terminal is connected to the output terminal of the low-pass filter circuit 130, and the first negative input terminal is connected to the first output terminal. The second operational amplifier includes a second positive input terminal, a second negative input terminal, and a second output terminal. The second positive input terminal is connected to the first output terminal, the second negative input terminal is connected to the second output terminal, and the second output terminal is also connected to the voltage divider point of the first voltage divider circuit 140.

[0043] By setting the voltage follower circuit 150 as a two-stage operational amplifier, the cost of the voltage follower circuit 150 can be reduced as much as possible, while making the voltage follower circuit 150 more suitable for circuits with higher requirements for accuracy and stability.

[0044] Optionally, such as Figure 4 As shown, the first output terminal can also be grounded through a third voltage divider circuit, and the second positive input terminal is connected to the voltage divider point of the third voltage divider circuit. The third voltage divider circuit may include a sixth resistor R6 and a seventh resistor R7 connected in series. The sixth resistor R6 is also connected to the first output terminal, and the seventh resistor R7 is also grounded. The second output terminal can also be connected to a sixth capacitor C6, the other end of which is grounded.

[0045] In some embodiments, such as Figure 4 As shown, the speed control circuit 100 may also include a third resistor R3, and the voltage follower circuit 150 can be connected to the voltage division point of the first voltage divider circuit 140 through the third resistor R3. That is, one end of the third resistor R3 is connected to the output terminal of the voltage follower circuit 150, and the other end of the third resistor R3 is connected to the voltage division point of the first voltage divider circuit.

[0046] By connecting a third resistor R3 between the voltage follower circuit 150 and the voltage divider point of the first voltage divider circuit 140, the voltage follower circuit 150 and the control circuit can be protected by the third resistor R3, thereby improving the stability of the circuit, limiting transient circuits, and suppressing noise.

[0047] As mentioned above, the voltage conversion circuit 110 is used to convert the power supply voltage into the fan power supply voltage based on the feedback voltage of the feedback terminal FB. This application does not impose specific limitations on the structure of the voltage conversion circuit 110, as long as the voltage conversion circuit 110 can convert the power supply voltage into the fan power supply voltage based on a closed-loop feedback mechanism.

[0048] As an example, such as Figure 2 and Figure 4As shown, the voltage conversion circuit 110 may include a BUCK chip 111 and an inductor L1. The BUCK chip 111 is a power management integrated circuit for implementing buck DC-DC conversion. The BUCK chip 111 internally integrates a closed-loop feedback control circuit formed by an error amplifier, a reference voltage power supply, and a PWM controller. The BUCK chip 111 may include multiple pins; for example, it may include a power input terminal VIN, a pulse voltage output terminal SW, and a feedback terminal FB. VIN forms the power input terminal of the voltage conversion circuit 110. FB forms the feedback terminal of the voltage conversion circuit 110. SW is connected to the power output terminal of the voltage conversion circuit 110 through the inductor L1. Alternatively, one end of the inductor L1 is connected to SW, and the other end of the inductor L1 forms the power output terminal of the voltage conversion circuit 110.

[0049] To further control the start and stop of the BUCK chip 111, in some embodiments, such as... Figure 2 and Figure 4 As shown, the BUCK chip 111 also includes an enable terminal EN, and the control circuit 120 includes a start / stop control terminal ON / OFF. The start / stop control terminal ON / OFF is connected to the enable terminal EN, and controls the enable terminal EN to start or stop the BUCK chip. Specifically, the start / stop control terminal ON / OFF is used to output a control signal to control the enable terminal EN to start or stop the BUCK chip 111. For example, when the start control terminal outputs a high level, the high level can pull the enable terminal EN pin high, thereby starting the BUCK chip 111. When the start control terminal outputs a low level, the low level can pull the enable terminal EN pin low, thereby stopping the BUCK chip 111.

[0050] In some embodiments, to enhance the safety of start-stop control, such as Figure 2 and Figure 4 As shown, the control circuit 120 may further include a first switching transistor Q1. The first terminal of the first switching transistor Q1 is connected to the power supply terminal VDD of the control circuit 120, the second terminal of the first switching transistor Q1 is connected to the enable terminal EN, and the control terminal of the first switching transistor Q1 is connected to the start / stop control terminal ON / OFF. Optionally, the control terminal of the first switching transistor Q1 can be connected to the start / stop control terminal ON / OFF via a filtering device. The filtering device is used to filter the control signal to remove noise, thereby further improving the safety of the start / stop control. As an example, such as... Figure 2 and Figure 4As shown, the filtering device may include an eighth resistor R8 and a third capacitor C3. One end of the eighth resistor R8 is connected to the ON / OFF control terminal, and the other end of the eighth resistor R8 is connected to the third capacitor C3, the other end of the third capacitor C3 being grounded. The control terminal of the first switching transistor Q1 is connected to the other end of the eighth resistor R8.

[0051] As previously mentioned, the control circuit 120 can generate a PWM signal based on the ambient temperature-related signal fed back by the temperature signal processing circuit 160. Therefore, in some embodiments, such as... Figure 2 and Figure 4 As shown, the speed control circuit 100 also includes a temperature signal processing circuit 160. The temperature signal processing circuit 160 includes an input terminal and an output terminal. The input terminal of the temperature signal processing circuit 160 is used to receive an ambient temperature detection signal. The ambient temperature detection signal can be obtained through a temperature detection circuit (…). Figures 1-4 (Not shown) The temperature is detected. The temperature detection circuit may include, for example, a negative temperature coefficient (NTC) thermistor. The output of the temperature signal processing circuit 160 is connected to the temperature detection interface NTC of the control circuit 120, and the temperature signal processing circuit 160 is used to process the received ambient temperature detection signal and transmit the processed signal to the control circuit 120. The magnitude of the electrical signal processed by the temperature signal processing circuit 160 can reflect the magnitude of the ambient temperature. By setting the temperature signal processing circuit 160 in the speed control circuit 100, the ambient temperature detection signal can be processed and converted by hardware circuitry. Compared with directly detecting the temperature through the chip itself, the requirements for the chip can be reduced, thereby reducing costs.

[0052] As one possible implementation, such as Figure 2 and Figure 4 As shown, the temperature signal processing circuit 160 also includes a pull-up resistor R9, a current-limiting resistor R10, and an interface protection circuit. The first terminal of the pull-up resistor R9 is connected to the power supply terminal VDD, and the second terminal of the pull-up resistor R9 receives the ambient temperature detection signal. The first terminal of the current-limiting resistor R10 is connected to the second terminal of the pull-up resistor R9, and the second terminal of the current-limiting resistor R10 is connected to the temperature detection interface NTC of the control circuit 120. Optionally, the second terminal of the current-limiting resistor R10 can also be grounded through a fourth capacitor C4. The first terminal of the interface protection circuit is connected to the second terminal of the pull-up resistor R9, and the second terminal of the interface protection circuit is grounded. The interface protection circuit is used to respond to and suppress voltage spikes in a very short time, thereby protecting the control circuit 120 from damage. As one implementation, the interface protection circuit can be as follows: Figure 2 and Figure 4The diagram shows a bidirectional transient voltage suppressor (TVS) D1. By setting pull-up resistor R9, current-limiting resistor R10, and interface protection circuitry, the safety of control circuit 120 can be ensured in all aspects.

[0053] As previously described, the control circuit 120 determines the fan supply voltage Vout based on its internal reference voltage Vref and the feedback voltage at the feedback terminal FB. In this embodiment, the PWM signal provided by the control circuit 120 is converted into a voltage signal by the low-pass filter circuit 130 and used to adjust the feedback voltage, thereby adjusting the fan supply voltage. The PWM signal is used by the low-pass filter circuit 130 to determine the voltage signal Vset, which is then used to adjust the feedback voltage at the feedback terminal FB. The feedback voltage at the feedback terminal FB is then used to adjust the fan supply voltage. Alternatively, the PWM signal is used by the low-pass filter circuit 130 to determine the voltage signal Vset, the adjusted feedback voltage is determined by the reference voltage Vref and the voltage signal Vset, and the adjusted fan supply voltage is determined by the adjusted feedback voltage and the reference voltage Vref.

[0054] To make it easier to understand, the following will be combined with... Figure 4 The circuit structure in the diagram will be explained in detail. It should be noted that... Figure 4 The values ​​of each resistor in the circuit are known, and the reference voltage Vref in the control circuit 120 is also known.

[0055] (1) Where Vout is the adjusted power supply voltage for the fan. The adjusted feedback voltage, This is a voltage signal converted from a PWM signal. The relationship between the duty cycle D in the PWM signal and the PWM signal can be specifically expressed by the following formula.

[0056] (2) Where N is a known constant.

[0057] Substitute formula (2) into formula (1), and then... Substituting R3, R5, and R4 into the equation, we can finally determine... It is a linear function related to D, and the larger D is, the better. The smaller the value, the smaller D is. The larger.

[0058] In addition, this application embodiment also provides a fan system, including a fan and the speed control circuit described above.

[0059] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any other combination. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this disclosure are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a machine-readable storage medium or transmitted from one machine-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The machine-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., digital video discs (DVDs)), or semiconductor media (e.g., solid-state drives (SSDs)).

[0060] In the several embodiments provided in this disclosure, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0061] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0062] In addition, the functional units in the various embodiments of this disclosure can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0063] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A speed control circuit, characterized in that, include: A voltage conversion circuit includes a power input terminal, a power output terminal, and a feedback terminal. The power input terminal is used to connect to a power source, and the power output terminal is used to connect to a fan to provide a power supply voltage for the fan. The power output terminal is also grounded through a first voltage divider circuit, and the feedback terminal is connected to the voltage divider point of the first voltage divider circuit. The voltage conversion circuit is used to convert the power supply voltage into the fan power supply voltage based on the feedback voltage of the feedback terminal. Control circuitry for generating pulse modulation signals based on ambient temperature; A low-pass filter circuit, wherein the input terminal of the low-pass filter circuit receives the pulse modulation signal, and the output terminal of the low-pass filter circuit is connected to the voltage division point of the first voltage divider circuit.

2. The speed regulating circuit according to claim 1, characterized in that, The low-pass filter circuit includes: The first filter circuit includes a first resistor and a first capacitor. The first end of the first resistor receives the pulse modulation signal, the second end of the first resistor is connected to the first end of the first capacitor, and the second end of the second capacitor is grounded. The second filter circuit includes a second resistor and a second capacitor. The first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is connected to the first end of the second capacitor. The second end of the second capacitor is grounded, and the second end of the second resistor is used to connect to the voltage divider point of the first voltage divider circuit.

3. The speed regulating circuit according to claim 1, characterized in that, The speed control circuit also includes: The voltage follower circuit includes a positive input terminal, a negative input terminal, and an output terminal. The positive input terminal is connected to the output terminal of the low-pass filter circuit, the negative input terminal is connected to the output terminal of the voltage follower circuit, and the output terminal of the voltage follower circuit is also connected to the voltage divider point of the first voltage divider circuit.

4. The speed regulating circuit according to claim 3, characterized in that, The voltage follower circuit includes: The first operational amplifier includes a first positive input terminal, a first negative input terminal, and a first output terminal. The first positive input terminal is connected to the output terminal of the low-pass filter circuit, and the first negative input terminal is connected to the first output terminal. The second operational amplifier includes a second positive input terminal, a second negative input terminal, and a second output terminal. The second positive input terminal is connected to the first output terminal, the second negative input terminal is connected to the second output terminal, and the second output terminal is also connected to the voltage divider point of the first voltage divider circuit.

5. The speed regulating circuit according to claim 3, characterized in that, The speed control circuit also includes: The third resistor has one end connected to the output terminal of the voltage follower circuit and the other end connected to the voltage divider point of the first voltage divider circuit.

6. The speed regulating circuit according to claim 1, characterized in that, The voltage conversion circuit includes a BUCK chip and an inductor. The control circuit includes a start / stop control terminal. The BUCK chip includes a pulse voltage output terminal and an enable terminal. The pulse voltage output terminal is connected to the power output terminal through the inductor. The enable terminal is connected to the start / stop control terminal so that the BUCK chip can be started or stopped by controlling the enable terminal.

7. The speed regulating circuit according to claim 6, characterized in that, The speed control circuit also includes: The first switching transistor has a first end connected to the power supply terminal, a second end connected to the enable terminal, and a control terminal connected to the start / stop control terminal.

8. The speed regulating circuit according to claim 1, characterized in that, The speed control circuit also includes: A temperature signal processing circuit, wherein the input terminal of the temperature signal processing circuit is used to receive the ambient temperature detection signal, and the output terminal of the temperature signal processing circuit is connected to the temperature detection interface of the control circuit.

9. The speed regulating circuit according to claim 8, characterized in that, The temperature signal processing circuit further includes: A pull-up resistor, the first end of which is connected to the power supply terminal, and the second end of which receives the ambient temperature detection signal; A current-limiting resistor, the first end of which is connected to the second end of the pull-up resistor, and the second end of which is connected to the temperature detection interface of the control circuit; An interface protection circuit is provided, wherein the first terminal of the interface protection circuit is connected to the second terminal of the pull-up resistor, and the second terminal of the interface protection circuit is grounded.

10. A fan system, characterized in that, include: Fan; And the speed control circuit as described in any one of claims 1-9.

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