Rotating speed control circuit, chip and method

Abstract

The invention provides a rotating speed control circuit, a chip and a method. The rotating speed control circuit comprises a PWM fan control unit electrically connected with the PWM fan and a voltage control unit. The PWM fan control unit adjusts the target output voltage of the voltage control unit according to the received PWM input signal, and adjusts the duty ratio of the PWM output signal according to the PWM input signal and the rotating speed detection signal of the PWM fan; the voltage control unit receives the target output voltage and provides power supply voltage for the PWM fan according to the target output voltage; and the PWM fan receives the PWM output signal and operates to reach a target rotating speed corresponding to the PWM input signal under the control of the power supply voltage and the PWM output signal. According to the invention, the PQ conversion efficiency can be obviously improved, and the energy-saving and consumption-reducing effects are realized; and the rotating speed of the PWM fan can be accurately controlled, and the requirements of various working conditions are met.

Description

Technical Field

[0001] The present invention relates to the technical field of PWM fan control, and in particular to a speed control circuit, chip and method. Background Art

[0002] With the rapid development of science and technology, electronic products are becoming more and more sophisticated, and the speed of operation is getting faster and faster, which generates more and more heat. In order to ensure that the system of electronic products can work normally, the heat dissipation of electronic devices is dissipated by cooling fans. In the prior art, most cooling fans pursue power consumption efficiency when running at full speed, but ignore that the cooling fan rotates at medium and low speeds when the system is running normally. According to investigation, the current fan speed control method basically adopts PWM control method to change the fan speed. However, after extensive research by the inventor, it was found that when the PWM control method is adopted, when the PWM fan runs at a low speed, the duty cycle of the PWM control signal is relatively small, resulting in poor P (Pressure) Q (Quantity) conversion efficiency.

[0003] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0004] The purpose of the present invention is to provide a speed control circuit, chip and method to solve the problem of low PQ conversion efficiency when the PWM fan is running at medium and low speeds by using a PMW control method to control the speed of the PWM fan in the prior art. The present invention provides a suitable power supply voltage for the PWM fan to control the speed of the PWM fan, and can keep the duty cycle of the PWM output signal received by the PWM fan (that is, the PWM control signal provided by the speed control circuit to the PWM fan) in a reasonable range, which can significantly improve the PQ conversion efficiency and achieve energy saving and consumption reduction effects; on the other hand, the present invention can further detect the speed detection signal of the PWM fan on the basis of adjusting the power supply voltage of the PWM fan, and fine-tune the speed by changing the duty cycle of the PWM output signal received by the PWM fan, so as to accurately control the speed of the PWM fan and meet the needs of various working conditions.

[0005] To achieve the above object, the present invention is implemented by the following technical solutions: a speed control circuit for a PWM fan, the speed control circuit comprising a PWM fan control unit and a voltage control unit electrically connected to the PWM fan;

[0006] The PWM fan control unit is used to adjust the target output voltage of the voltage control unit according to the received PWM input signal, and adjust the duty cycle of the PWM output signal according to the PWM input signal and the speed detection signal of the PWM fan;

[0007] The voltage control unit is used to receive the target output voltage and provide a power supply voltage for the PWM fan according to the target output voltage;

[0008] The PWM fan receives the PWM output signal and operates under the control of the power supply voltage and the PWM output signal to reach a target rotation speed corresponding to the PWM input signal.

[0009] Optionally, the voltage control unit receives an input voltage and converts the input voltage into the supply voltage according to the target output voltage. The output end of the voltage control unit is coupled to the PWM fan and provides the supply voltage to the PWM fan.

[0010] Optionally, the PWM input signal comes from a wireless communication signal or a host controller electrically connected to the PWM fan control unit.

[0011] Optionally, the voltage control unit includes a voltage control circuit, which receives the target output voltage and controls the supply voltage output by the voltage control unit, and the voltage control circuit is integrated in a chip.

[0012] Optionally, the PWM fan control unit detects a duty cycle of the PWM input signal, and obtains the target output voltage according to an editable correspondence between the duty cycle of the PWM input signal and the target output voltage;

[0013] Among them, when the duty cycle of the PWM input signal is larger, the corresponding target output voltage is higher.

[0014] Optionally, the PWM fan control unit obtains the target speed based on the correspondence between an editable PWM input signal duty cycle and the target speed, and adjusts the duty cycle of the PWM output signal according to the target speed and the speed detection signal. The speed detection signal received by the PWM fan control unit reflects the speed detection signal of the PWM fan.

[0015] Optionally, the PWM fan control unit is arranged on a first control chip and the voltage control circuit is arranged on a second control chip, or the PWM fan control unit and the voltage control circuit are arranged on the same chip.

[0016] In order to achieve the above-mentioned objectives, the present invention also provides a speed control chip for a PWM fan, wherein the speed control chip integrates a PWM fan control unit of the speed control circuit described in any of the above items, and the speed control chip is electrically connected to the voltage control unit and provides the target output voltage to the voltage control unit.

[0017] In order to achieve the above object, the present invention further provides another speed control chip for a PWM fan, wherein the speed control chip integrates the PWM fan control unit and the voltage control unit.

[0018] In order to achieve the above object, the present invention further provides a speed control method for a PWM fan, the speed control method comprising:

[0019] Receive PWM input signal;

[0020] adjusting the supply voltage of the PWM fan and the duty cycle of the PWM output signal according to the PWM input signal;

[0021] The power supply voltage is provided to the PWM fan, and the duty cycle of the PWM output signal is adjusted according to the rotation speed detection signal of the PWM fan, so as to control the PWM fan to operate at a target rotation speed corresponding to the PWM input signal.

[0022] Compared with the prior art, the speed control circuit, chip and method provided by the present invention have the following advantages:

[0023] The speed control circuit for a PWM fan provided by the present invention comprises a PWM fan control unit and a voltage control unit electrically connected to the PWM fan, wherein the PWM fan control unit is used to adjust the target output voltage of the voltage control unit according to the received PWM input signal, and adjust the duty cycle of the PWM output signal according to the PWM input signal and the speed detection signal of the PWM fan; the voltage control unit is used to receive the target output voltage and provide a power supply voltage for the PWM fan according to the target output voltage; the PWM fan receives the PWM output signal and operates under the control of the power supply voltage and the PWM output signal to achieve a target speed corresponding to the PWM input signal. Therefore, the speed control circuit for a PWM fan provided by the present invention includes a PWM fan control unit and a voltage control unit, and the PWM fan control unit can adjust the target output voltage of the voltage control unit according to the received PWM input signal (for example, the target output voltage is reduced when the target speed corresponding to the PWM input signal is low, and the target output voltage is increased when the corresponding target speed is high). On the one hand, the present invention controls the speed of the PWM fan by providing a suitable power supply voltage to the PWM fan, and can keep the duty cycle of the PWM output signal received by the PWM fan (that is, the PWM control signal provided by the speed control circuit to the PWM fan) in a reasonable range, and minimize the power supply voltage under the premise of achieving the target speed, thereby reducing power losses such as switching losses, and significantly improving the PQ conversion efficiency, and achieving energy saving and consumption reduction effects; on the other hand, the present invention, on the basis of adjusting the PWM fan supply voltage, further detects the speed detection signal of the PWM fan, and fine-tunes the speed by changing the duty cycle of the PWM output signal received by the PWM fan (for example, when it is detected that the PWM fan speed is too fast, the duty cycle is reduced, and when the speed is too slow, the duty cycle is increased), so that the PWM fan speed can be accurately controlled to meet the needs of various working conditions.

[0024] The speed control chip and method provided by the present invention belong to the same inventive concept as the speed control circuit provided by the present invention. Therefore, the speed control chip and method provided by the present invention at least have all the advantages of the speed control circuit provided by the present invention. In order to avoid redundancy, no further explanation is given here. For more details, please refer to the relevant description of the beneficial effects of the speed control circuit provided by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of a speed control circuit in the prior art;

[0026] Figure 2 A structural block diagram of a speed control circuit provided by the present invention;

[0027] Figure 3A schematic diagram of the circuit structure of a speed control circuit provided in a first embodiment of the present invention;

[0028] Figure 4 A schematic diagram of the circuit structure of a speed control circuit provided in a second embodiment of the present invention;

[0029] Figure 5a A schematic diagram showing the PQ characteristics when a PWM fan is controlled by the speed control circuit provided by the present invention and the PQ efficiency comparison of a PWM fan when a PWM control method is used in the prior art;

[0030] Figure 5b It is a waveform diagram of a PWM output signal of a PWM fan when a PWM control method is adopted in the prior art;

[0031] Figure 5c A waveform diagram of a PWM output signal when a PWM fan is controlled by the speed control circuit provided by the present invention;

[0032] Figure 6 A flow chart of a speed control method provided in one embodiment of the present invention;

[0033] The reference numerals are as follows:

[0034] PWM fan control chip-100; PWM fan-200, switch tube control circuit-210, motor-220;

[0035] PWM fan control unit-300, signal interface circuit-310, main control circuit-320, main control module-321, voltage stabilizing module-322, driving module-323;

[0036] Voltage control unit 400, voltage control circuit 410, DC-DC conversion module 411, DC-DC controller 412, controlled MOS tube circuit 413, inductor 420, capacitor 430;

[0037] Diodes-510, 520;

[0038] PWM input signal - PWM IN , PWM output signal - PWM OUT , input voltage -V IN , target output voltage -V GOAL , supply voltage -V OUT ; Speed ​​detection signal-FG OUT . DETAILED DESCRIPTION

[0039] The following is a further detailed description of the speed control circuit, chip and method proposed in the present invention in conjunction with the accompanying drawings. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Any modification of the structure, change in the proportional relationship or adjustment of the size, under the same or similar conditions as the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention. The specific design features of the present invention disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific environment to be applied and used. And, in the embodiments described below, sometimes the same figure mark is used in common between different drawings to represent the same part or part with the same function, and its repeated description is omitted. In this specification, similar reference numerals and letters are used to denote similar items, and thus, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0040] It should be noted that if the method described herein includes a series of steps, the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method. In addition, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

[0041] It should be understood that in the description of the present invention, unless otherwise clearly specified and limited, when a component is referred to as being "connected", "connected to", or "coupled to" another component, it may be directly connected to the other component, or there may be intervening components. On the contrary, when a component is referred to as being "directly connected" or "directly connected to" another component, there are no intervening components.

[0042] In order to facilitate the understanding of the present invention, before describing in detail the specific embodiments of the speed control circuit, chip and method provided by the present invention, the main research process of proposing the present invention is briefly described as follows:

[0043] Please see attached Figure 1 , Figure 1 It is a structural schematic diagram of a speed control circuit in the prior art. Figure 1 In, PWM IN To receive the host computer ( Figure 1 The PWM fan control chip 100 built in the PWM fan 200 calculates the duty cycle of the PWM control signal required to achieve the target speed, and then drives the switch control circuit 210 according to the PWM control signal, thereby driving the motor 220 of the PWM fan 200 to make the PWM fan 200 reach the required speed. However, it has been found through research that this method completely uses the PWM control signal to control the speed, and only uses the PWM control method. When the PWM fan 200 runs at a low speed, the lower the duty cycle, the worse its PQ efficiency.

[0044] Based on the above research, in order to solve the problem of low PQ conversion efficiency when the PWM fan is running at medium and low speeds when the PWM fan is controlled by the PMW control method, different from the prior art that only uses the PWM control method, the present invention adds a voltage control unit on the basis of the existing PWM fan internal control chip, and uses the "power supply voltage + PWM duty cycle" method to accurately control the speed of the PWM fan.

[0045] In order to realize the above idea, the present invention provides a speed control circuit for a PWM fan. For example, see Figure 2 , Figure 2 This is a structural block diagram of the speed control circuit provided by the present invention. Figure 2 As shown, the speed control circuit provided by the present invention includes a PWM fan control unit 300 and a voltage control unit 400 electrically connected to the PWM fan 200. Further, the PWM fan control unit 300 is used to receive a PWM input signal PWM IN Adjust the target output voltage V of the voltage control unit 400 GOAL , and according to the PWM input signal PWM IN and the speed detection signal FG of the PWM fan 200 OUT Adjust PWM output signal PWM OUT The voltage control unit 400 is used to receive the target output voltage V GOAL , and according to the target output voltage V GOAL Provides a power supply voltage V for the PWM fan 200 OUT ; The PWM fan 200 receives the PWM output signal PWM OUT , and at the supply voltage V OUTAnd the PWM output signal PWM OUT The PWM input signal PWM is controlled by IN The corresponding target speed.

[0046] Therefore, the speed control circuit for the PWM fan 200 provided by the present invention includes a PWM fan control unit 300 and a voltage control unit 400, and the PWM fan control unit 300 can receive a PWM input signal PWM IN Adjust the target output voltage V of the voltage control unit 400 GOAL (For example, PWM input signal PWM IN When the corresponding target speed is low, the target output voltage V is reduced. GOAL , when the corresponding target speed is high, the target output voltage V is increased GOAL ), on the one hand, the present invention provides a suitable power supply voltage V for the PWM fan 200 OUT To control the speed of the PWM fan 200, the PWM output signal PWM received by the PWM fan 200 can be OUT The duty cycle of the PWM control signal (that is, the PWM control signal provided by the speed control circuit to the PWM fan) is kept in a reasonable range, and the supply voltage V is minimized while achieving the target speed. OUT , thereby reducing power losses such as switching losses, can significantly improve PQ conversion efficiency, and can achieve energy saving and consumption reduction effects; on the other hand, the present invention adjusts the PWM fan 200 power supply voltage V OUT Based on this, the speed detection signal FG of the PWM fan 200 is further detected. OUT and by changing the PWM fan 200 received PWM output signal PWM OUT The duty cycle of the PWM fan 200 can be fine-tuned (for example, when it is detected that the speed of the PWM fan 200 is too fast, the duty cycle is reduced, and when the speed is too slow, the duty cycle is increased). The speed of the PWM fan 200 can be accurately controlled to meet the needs of various working conditions.

[0047] For example, in some of the exemplary embodiments, please continue to refer to Figure 2 ,like Figure 2 As shown, the voltage control unit 400 receives an input voltage V IN , and according to the target output voltage V GOAL The input voltage V IN Converts the supply voltage V OUT The output terminal of the voltage control unit 400 is coupled to the PWM fan 200 and provides the power supply voltage V to the PWM fan 200. OUT Therefore, the speed control circuit provided by the present invention receives the input voltage V through the voltage control unit 400.IN And according to the target output voltage V set by the PWM fan control unit 300 GOAL The input voltage V IN Converted into the supply voltage V provided to the PWM fan 200 OUT , so that the PWM fan can run at the target speed while maintaining the PWM output signal PWM OUT The duty cycle is in a reasonable range.

[0048] For example, in some exemplary embodiments, the PWM input signal PWM IN from a wireless communication signal; in some other exemplary embodiments, the PWM input signal PWM IN It may also come from a higher-level controller (not shown in the figure) electrically connected to the PWM fan control unit 300. With such configuration, the speed control circuit provided by the present invention has better applicability.

[0049] It should be noted that, as those skilled in the art can understand, the above-mentioned PWM input signal PWM IN The source is only an exemplary description of a preferred embodiment, and is not a limitation of the present invention. The present invention has no limitation on the PWM input signal PWM IN There is no restriction on the source.

[0050] Preferably, in some of the exemplary embodiments, see Figure 3 , Figure 3 The circuit structure diagram of the speed control circuit provided by the first embodiment of the present invention is shown in FIG. Figure 3 It can be seen that the voltage control unit 400 includes a voltage control circuit 410, and the voltage control circuit 410 receives the target output voltage V GOAL , and controls the supply voltage V output by the voltage control unit 400 OUT , the voltage control circuit 410 is integrated into the chip ( Figure 4 In the embodiment shown in gray, the control circuit and the controlled switch element are included. It can be seen that by adopting the design method of integrating the voltage control circuit 410 into the chip, the integration level of the PWM fan with the speed control circuit provided by the present invention can be significantly improved.

[0051] For example, in some of the exemplary embodiments, please continue to refer to Figure 3 ,like Figure 3 As shown, the speed control circuit provided by the first embodiment of the present invention has a voltage control circuit 410 including a DC-DC conversion module 411, the input end of which receives the input voltage V INThe control end of the DC-DC conversion module 411 is coupled to the PWM fan control unit 300 to receive the target output voltage V GOAL The output end of the DC-DC conversion module 411 is coupled to the switch control circuit 210 of the PWM fan 200. Further, as mentioned above, the voltage control circuit 410 is separately integrated in the chip.

[0052] For example, in some other implementations, see Figure 4 , Figure 4 FIG. 1 is a schematic diagram of the circuit structure of a speed control circuit provided in the second embodiment of the present invention. Figure 4 As shown, in this embodiment, the voltage control circuit 410 of the speed control circuit includes a DC-DC controller 412 and a controlled MOS transistor circuit 413, and the input end of the DC-DC controller 412 and the input end of the controlled MOS transistor circuit 413 are used to receive the input voltage V IN , the control end of the DC-DC controller 412 is coupled to the PWM fan control unit 300, the output end of the DC-DC controller 412 is coupled to the control end of the controlled MOS tube circuit 413, and the output end of the controlled MOS tube circuit 413 is coupled to the switch tube control circuit 210 of the PWM fan 200. The DC-DC controller 412 is separately integrated in the chip (indicated by the gray box in FIG. 5 ), so that the controlled MOS tube circuit 413 is separated from the DC-DC controller 412. This implementation is particularly suitable for high current and high power consumption scenarios.

[0053] It should be noted that the voltage control circuit 410 can be implemented by a BUCK circuit, a BOOST circuit or a combination thereof. For more detailed information about the DC-DC conversion module 411 and the DC-DC controller 412, please refer to the understanding of the adaptability of the relevant technologies regarding the voltage conversion circuit known to those skilled in the art. Due to space limitations, this article will not elaborate on the DC-DC conversion module 411 and the DC-DC controller 412.

[0054] Next, combine Figure 3 The speed control circuit provided by the present invention is further described. In order to avoid redundancy, Figure 4 Please refer to the following description for an adaptive understanding of the relevant contents of the illustrated implementation method.

[0055] like Figure 3 As shown, the speed control circuit may also include a device for improving stability and anti-interference capability. For example, the voltage control circuit 410 is further coupled to a diode 510 and a diode 520 for inputting a voltage V INFurthermore, the voltage control unit 400 may further include an inductor 420, which is coupled between the DC-DC conversion module 411 and the switch tube control circuit 210 of the PWM fan 200, thereby further increasing the supply voltage V output by the speed control circuit provided by the present invention. OUT stability; further, the voltage control unit 400 may also include a capacitor 430. After the voltage control circuit 410 is coupled to the inductor 420, the capacitor 430 is connected in series and then grounded, thereby further improving the anti-interference performance of the voltage control unit 400 provided by the present invention.

[0056] It should be noted that, as those skilled in the art can understand, the present invention does not impose too many limitations on the specific implementation of the PWM fan control unit 300. Figure 3 For example, Figure 3 As shown, in some exemplary embodiments, the PWM fan control unit 300 may include a signal interface circuit 310 and a main control circuit 320, wherein the main control circuit 320 includes a main control module 321, a voltage stabilizing module 322 and a driving module 323, and the main control module 321 may detect the speed of the PWM fan 200 to obtain a speed detection signal FG of the PWM fan 200. OUT , or receive the speed detection signal FG via the signal interface circuit 310 OUT Furthermore, the main control circuit 320 can be integrated into a chip built into the PWM fan 200 ( Figure 3 Furthermore, the PWM fan control unit 300 can also detect the speed of the PWM fan 200 using the gray box; OUT Feedback to the host controller so that the host controller can better control the system, including but not limited to adjusting the PWM input signal PWM IN For more detailed information about the PWM fan control unit 300, please refer to the relevant technical adaptability understanding of the PWM fan 200 control known to those skilled in the art. Due to space limitations, the PWM fan control unit 300 will not be further described in this article.

[0057] It should be particularly noted that those skilled in the art should be able to understand that the present invention does not impose too many restrictions on the specific connection method between the PWM fan control unit 300 and the voltage control unit 400. For example, in some exemplary implementations, they can be connected through their respective I / O pins.

[0058] The following combination Figure 3 The working process of the speed control circuit provided by the present invention is briefly described as follows:

[0059] Host controller ( Figure 3 ) sends a PWM input signal PWM to the PWM fan 200 IN

[0060] To control the speed of the PWM fan 200, the PWM fan control unit 300 receives the PWM input signal PWM IN Then according to the PWM input signal PWM IN Set the target output voltage V of the voltage control unit 400 GOAL , the target output voltage V GOAL The PWM input signal PWM provided by the host computer to the PWM fan 200 IN When the PWM input signal PWM provided by the host computer is adjusted IN After fixing, the voltage control unit 400 provides the power supply voltage V OUT The supply voltage V OUT Under the condition that the speed of the PWM fan 200 is slightly higher or lower than the PWM input signal PWM IN The corresponding target speed, at this time, the PWM fan control unit 300 will be based on the PWM input signal PWM IN The speed detection signal of the PWM fan 200 adjusts the PWM output signal PWM OUT The duty cycle of the PWM fan 200 is set so that the speed of the PWM fan 200 reaches the same value as the PWM input signal PWM IN The corresponding target speed.

[0061] In order to make the present invention more understandable, the following takes the relevant test statistical data of a PWM fan of the same model with parameters of input voltage 48V, full speed 33000PRM (rev / min) and half speed 16500PRM (rev / min) as an example to provide a more intuitive explanation of the beneficial effects of the speed control circuit provided by the present invention.

[0062] First, see Figure 5a , Figure 5a The figure is a schematic diagram comparing the PQ characteristics when the speed control circuit provided by the present invention is used to control a PWM fan and the PQ efficiency of the PWM fan when the PWM control method is used in the prior art.

[0063] Figure 5a Middle: Left vertical axis P STP is the wind pressure under standard test conditions, in mmAq, 1 mmAq = 9.80665 Pa; the horizontal axis Q STPis the air volume under standard test conditions, the unit is CFM, 1CFM = 0.000471947443 cubic meters per second; the vertical axis on the right is the PQ efficiency, which can be calculated by the following formula:

[0064] PQ efficiency = (wind pressure × wind volume) ÷ power consumption

[0065] In the above formula, the unit of wind pressure is Pascal (Pa), the unit of air volume is cubic meter per second, and the unit of power is Watt (W).

[0066] from Figure 5a It can be seen that when the prior art "PWM control" is used at 50% speed (16500PRM), the PQ efficiency is up to 31.69%, and when the speed control circuit provided by the present invention is used at 50% speed (16500PRM) of the PWM fan, the PQ efficiency (indicated by the long dashed line in the figure) is up to 39.61%. It can be seen that the speed control circuit provided by the present invention has a higher PQ efficiency. Compared with the prior art (same test conditions and PWM fan), the speed control circuit provided by the present invention significantly reduces power consumption (about 20%) and significantly improves PQ efficiency (about 7.92%).

[0067] Next, see Figure 5b and Figure 5c ,in, Figure 5b It is a waveform diagram of a PWM output signal of a PWM fan when a PWM control method is adopted in the prior art; Figure 5c This is a waveform diagram of the PWM output signal when the speed control circuit provided by the present invention is used to control the PWM fan. Figure 5b and Figure 5c It can be seen that: when the "PWM control" method of the prior art is adopted, the duty cycle of the PWM output signal is relatively low and the power supply voltage is relatively high, which causes the switch tube of the switch tube control circuit 210 to have a large switching loss when switching, so the power consumption is high and the PQ efficiency is low; while the speed control circuit provided by the present invention adopts a control method that combines reducing the power supply voltage and increasing the duty cycle of the PWM output signal, so that when the PWM fan runs near the target speed, the duty cycle of the PWM output signal is relatively high and the power supply voltage is relatively low, which can significantly reduce the loss when the switch tube is switched and improve the PQ efficiency during low-speed operation. At the same time, the feedback control of the fan speed is added for fine-tuning to ensure accurate control of the speed.

[0068] Preferably, in some exemplary embodiments, the PWM fan control unit 300 detects the PWM input signal PWM IN The target output voltage V is obtained according to the corresponding relationship between the duty cycle of the PWM input signal and the target output voltage.GOAL ; Wherein, the PWM input signal PWM IN The larger the duty cycle, the corresponding target output voltage V GOAL Therefore, the speed control circuit provided by the present invention can obtain the target output voltage V according to the corresponding relationship between an editable PWM input signal duty cycle and the target output voltage through the PWM fan control unit 300. GOAL , which can not only further improve the control accuracy of the speed control circuit provided by the present invention, but also has simple logic and is easy to implement.

[0069] It should be noted that, as can be understood by those skilled in the art, the present invention does not impose too many restrictions on the manner of obtaining the correspondence between the editable PWM input signal and the target output voltage. For example, in some embodiments, the PWM input signal PWM IN With the supply voltage V OUT The corresponding relationship between the PQ efficiency and the duty cycle is pre-calibrated; in other embodiments, it can also be personalized as needed. For example, it can be edited by the upper controller and communicated with the PWM fan control unit 300 via the signal interface circuit. Further, the present invention provides how the PWM fan control unit 300 obtains the target output voltage V through an editable corresponding relationship between the PWM input signal duty cycle and the target output voltage. GOAL The specific implementation method is not limited too much. For example, in some embodiments, the corresponding relationship between the editable PWM input signal duty cycle and the target output voltage can be pre-stored in the memory of the PWM fan control unit 300 and implemented through software control.

[0070] For example, please refer to Table 1, which shows the corresponding relationship between the editable PWM input signal duty cycle and the target output voltage of a specific example.

[0071] Table 1:

[0072] PWM IN duty cycle 100％ 90％ 80％ 70％ 60％ 50％ 40％ 30％％ 20％ 10％ 0％ DCDC Vout 48 43.2 38.4 33.6 28.8 24 19.2 14.4 9.6 4.8 0

[0073] In Table 1, PWM IN duty cycle is the duty cycle of the PWM input signal, and DCDC out is the target output voltage in volts (V).

[0074] Preferably, in some exemplary embodiments, the PWM fan control unit 300 obtains the target speed according to a corresponding relationship between an editable PWM input signal duty cycle and the target speed, and adjusts the PWM output signal PWM according to the target speed and the speed detection signal. OUTThe speed detection signal received by the PWM fan control unit 300 reflects the speed detection signal FG of the PWM fan 200. OUT Thus, the PWM fan control unit 300 of the speed control circuit provided by the present invention obtains the target speed according to the corresponding relationship between an editable PWM input signal duty cycle and the target speed, and obtains the speed detection signal FG according to the target speed and the speed detection signal. OUT Adjust the PWM output signal PWM OUT The duty cycle can not only further improve the control accuracy of the speed control circuit provided by the present invention, but also has simple logic and is easy to implement.

[0075] For example, please refer to Table 2, which shows the corresponding relationship between the editable PWM input signal duty cycle and the target speed in a specific example.

[0076] Table 2:

[0077] PWM IN duty cycle 100％ 90％ 80％ 70％ 60％ 50％ 40％ 30％ 20％ 10％ 0％ SPEED RPM 33000 29700 26400 23100 19800 16500 13200 9900 6600 3300 0

[0078] In Table 2, PWM IN duty cycle is the duty cycle of the PWM input signal; SPEED RPM is the target speed in revolutions per minute (RPM).

[0079] Finally, taking the PWM input signal duty cycle of 50% as an example, combined with Figure 3 Table 1 and Table 2 further illustrate the working process of the speed control circuit provided by the present invention as follows:

[0080] First, when the PWM input signal PWM IN When the duty cycle is 50%, according to Table 1, the required target output voltage V GOAL is 24V; according to Table 2, the desired target speed is 16500RPM; at this time, the PWM fan control unit 300 receives the PWM input signal PWM IN The duty cycle is 50%, and the voltage control unit 400 is provided with the target output voltage V GOAL The voltage control unit 400 provides a 24V supply voltage V to the PWM fan 200. OUT At the same time, the PWM fan control unit 300 will also determine whether the speed of the PWM fan 200 reaches the required target speed: if the speed is too low, the PWM fan control unit 300 will increase the PWM output signal PWM OUT If the speed is too high, the PWM output signal PWM is reduced. OUT The duty cycle of the PWM fan 200 is thus INThe corresponding target speed (16500RPM) is operated.

[0081] It should be noted that, as can be understood by those skilled in the art, the present invention does not impose too many restrictions on the acquisition method of the corresponding relationship between the editable PWM input signal duty cycle and the target speed. For example, in some embodiments, it can be pre-calibrated; in other embodiments, it can also be personalized as needed, or obtained through a host controller.

[0082] It should be further explained that those skilled in the art should be able to understand that the present invention does not impose any limitation on the specific implementation of the speed control circuit. For example, in some exemplary embodiments, the PWM fan control unit 300 is arranged on a first control chip and the voltage control circuit 410 is arranged on a second control chip. As a result, the system using the speed control circuit provided by the present invention has better design flexibility. For another example, in some other exemplary embodiments, the PWM fan control unit 300 and the voltage control circuit 410 are arranged on the same chip, and thus, the system using the speed control circuit provided by the present invention has better integration.

[0083] Another embodiment of the present invention provides a speed control chip for a PWM fan, wherein the speed control chip integrates a PWM fan control unit of the speed control circuit described in any of the above embodiments, and the speed control chip is electrically connected to the voltage control unit, and provides the target output voltage to the voltage control unit. The speed control chip provided by the present invention belongs to the same inventive concept as the speed control circuit provided by the present invention. Therefore, the speed control chip provided by the present invention has at least all the advantages of the speed control circuit provided by the present invention. In order to avoid redundancy, it will not be described in detail here. For more detailed content, please refer to the relevant description of the beneficial effects of the speed control circuit provided by the present invention.

[0084] Another embodiment of the present invention further provides a speed control chip for a PWM fan, wherein the speed control chip integrates the PWM fan control unit and the voltage control unit. Thus, a chip integrating the PWM fan control unit and the voltage control unit can achieve precise control of the PWM fan, thereby effectively saving energy consumption. The speed control chip provided by the present invention can further effectively improve the integration and performance of the system.

[0085] Another embodiment of the present invention provides a speed control method for a PWM fan. For example, see Figure 6 , Figure 6 Flow chart of the speed control method provided in this embodiment. Figure 6It can be seen that the speed control method provided in this embodiment includes:

[0086] S100: receiving PWM input signal;

[0087] S200: adjusting the supply voltage of the PWM fan and the duty cycle of the PWM output signal according to the PWM input signal;

[0088] S300: providing the power supply voltage to the PWM fan, and adjusting the duty cycle of the PWM output signal according to the speed detection signal of the PWM fan, so as to control the PWM fan to operate at a target speed corresponding to the PWM input signal.

[0089] It can be seen that the speed control method provided by the present invention can control the speed of the PWM fan by providing a suitable power supply voltage to the PWM fan, so as to keep the duty cycle of the PWM output signal received by the PWM fan (that is, the PWM control signal provided to the PWM fan) in a reasonable range, and minimize the power supply voltage while achieving the target speed, thereby reducing power losses such as switching losses, and significantly improving the PQ conversion efficiency, thereby achieving energy saving and consumption reduction effects; on the other hand, the present invention, on the basis of adjusting the power supply voltage of the PWM fan, further detects the speed detection signal of the PWM fan, and fine-tunes the speed by changing the duty cycle of the PWM output signal received by the PWM fan (for example, reducing the duty cycle when it is detected that the PWM fan speed is too fast, and increasing the duty cycle when the speed is too slow), so as to accurately control the speed of the PWM fan to meet the needs of various working conditions.

[0090] For example, in some exemplary implementations, step S200 adjusts the supply voltage of the PWM fan according to the PWM input signal, including:

[0091] According to a corresponding relationship between an editable PWM input signal duty cycle and a target output voltage, a target output voltage is obtained, and according to the target output voltage, a power supply voltage of the PWM fan is adjusted.

[0092] Preferably, when the duty cycle of the PWM input signal is larger, the corresponding target output voltage is higher.

[0093] For example, in some exemplary implementations, step S300 adjusts the duty cycle of the PWM output signal according to the real-time rotation speed of the PWM fan, including:

[0094] When the real-time speed of the PWM fan is lower than the target speed corresponding to the PWM output signal, the duty cycle of the PWM output signal is increased; when the real-time speed of the PWM fan is higher than the target speed corresponding to the PWM output signal, the duty cycle of the PWM output signal is reduced.

[0095] Since the speed control method for a PWM fan provided by the present invention has the same basic principle as the speed control circuit provided by the present invention, for the parts not mentioned in this embodiment, please refer to the relevant description of the speed control circuit of the PWM fan provided by the present invention in the above text for adaptive understanding. Due to space limitations, the speed control method for a PWM fan provided by the present invention will not be described in detail.

[0096] In summary, compared with the prior art, the speed control circuit, chip and method provided by the present invention have the following advantages:

[0097] The speed control circuit for a PWM fan provided by the present invention comprises a PWM fan control unit and a voltage control unit, and the PWM fan control unit can adjust the target output voltage of the voltage control unit according to the received PWM input signal (for example, the target output voltage is reduced when the target speed corresponding to the PWM input signal is low, and the target output voltage is increased when the corresponding target speed is high). On the one hand, the present invention controls the speed of the PWM fan by providing a suitable power supply voltage to the PWM fan, and can keep the duty cycle of the PWM output signal received by the PWM fan (that is, the PWM control signal provided to the PWM fan) in a reasonable range, and reduce the power supply voltage as much as possible under the premise of achieving the target speed, thereby reducing power losses such as switching losses, and can significantly improve the PQ conversion efficiency, and can achieve energy saving and consumption reduction effects; on the other hand, on the basis of adjusting the PWM fan supply voltage, the present invention further detects the speed detection signal of the PWM fan, and fine-tunes the speed by changing the duty cycle of the PWM output signal received by the PWM fan (for example, when it is detected that the PWM fan speed is too fast, the duty cycle is reduced, and when the speed is too slow, the duty cycle is increased), so that the PWM fan speed can be accurately controlled to meet the needs of various working conditions.

[0098] In addition, the functional modules in the various embodiments of this document may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0099] The above description is only a description of the preferred implementation of the speed control circuit, chip and method provided by the present invention, and is not intended to limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure are within the scope of protection of the present invention. Obviously, technicians in this field can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. In this way, if these modifications and variations fall within the scope of the present invention and its equivalent technology, the present invention is also intended to include these modifications and variations.

Claims

1. A speed control circuit for a PWM fan, characterized in that: The speed control circuit includes a PWM fan control unit and a voltage control unit electrically connected to the PWM fan; The PWM fan control unit is used to adjust the target output voltage of the voltage control unit according to the received PWM input signal, and adjust the duty cycle of the PWM output signal according to the PWM input signal and the speed detection signal of the PWM fan; The voltage control unit is used to receive the target output voltage and provide a power supply voltage for the PWM fan according to the target output voltage; The PWM fan receives the PWM output signal and operates under the control of the power supply voltage and the PWM output signal to reach a target rotation speed corresponding to the PWM input signal.

2. The speed control circuit according to claim 1, characterized in that: The voltage control unit receives an input voltage and converts the input voltage into the supply voltage according to the target output voltage. The output terminal of the voltage control unit is coupled to the PWM fan and provides the supply voltage to the PWM fan.

3. The speed control circuit according to claim 1, characterized in that: The PWM input signal comes from a wireless communication signal or a host controller electrically connected to the PWM fan control unit.

4. The speed control circuit according to claim 1 or 2, characterized in that: The voltage control unit includes a voltage control circuit, which receives the target output voltage and controls the supply voltage output by the voltage control unit. The voltage control circuit is integrated in a chip.

5. The speed control circuit according to claim 1, characterized in that: The PWM fan control unit detects the duty cycle of the PWM input signal, and obtains the target output voltage according to an editable correspondence between the duty cycle of the PWM input signal and the target output voltage; Among them, when the duty cycle of the PWM input signal is larger, the corresponding target output voltage is higher.

6. The speed control circuit according to claim 5, characterized in that: The PWM fan control unit obtains the target speed based on the correspondence between an editable PWM input signal duty cycle and the target speed, and adjusts the duty cycle of the PWM output signal based on the target speed and the speed detection signal. The speed detection signal received by the PWM fan control unit reflects the speed detection signal of the PWM fan.

7. The speed control circuit according to claim 4, characterized in that: The PWM fan control unit is arranged on a first control chip and the voltage control circuit is arranged on a second control chip, or the PWM fan control unit and the voltage control circuit are arranged on the same chip.

8. A speed control chip for a PWM fan, characterized in that: The speed control chip integrates a PWM fan control unit of the speed control circuit according to any one of claims 1 to 7, and the speed control chip is electrically connected to the voltage control unit and provides the target output voltage to the voltage control unit.

9. A speed control chip for a PWM fan, characterized in that: The speed control chip integrates the PWM fan control unit and the voltage control unit as claimed in claim 4.

10. A speed control method for a PWM fan, characterized in that: The speed control method comprises: Receive PWM input signal; adjusting the supply voltage of the PWM fan and the duty cycle of the PWM output signal according to the PWM input signal; The power supply voltage is provided to the PWM fan, and the duty cycle of the PWM output signal is adjusted according to the rotation speed detection signal of the PWM fan, so as to control the PWM fan to operate at a target rotation speed corresponding to the PWM input signal.

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