Automatic voltage transformation and speed regulation system of direct-current fan

Abstract

The invention discloses an automatic voltage transformation and speed regulation system for a direct current fan, and relates to the technical field of fan speed regulation, the system comprises a DC-DC unit used for realizing output voltage adjustable DC-DC power conversion in a wide input voltage range; the feedback automatic adjusting unit is used for collecting the output voltage of the DC-DC unit, comparing the output voltage with the control quantity input from the fan rotating speed control unit to obtain an error signal, and adjusting the output voltage of the DC-DC unit based on the error signal; and the fan rotating speed control unit is used for generating control voltage based on temperature detection or pulse signal conditioning and taking the control voltage as a control quantity to drive the feedback automatic adjusting unit so as to realize automatic control or active control of the rotating speed of the direct-current fan. Dynamic control over the rotating speed of the fan is achieved by automatically adjusting the input voltage of the direct-current fan, an automatic or active speed adjusting mode can be achieved according to temperature changes or external PWM signals, and the fan can be compatible with power supply voltage in a wider range.

Description

Technical Field

[0001] The present invention relates to the technical field of fan speed regulation, in particular to an automatic voltage-changing speed regulation system for a DC fan. Background Art

[0002] In energy storage temperature control systems, fans typically run continuously at a constant speed. The power supply system provides a fixed, constant voltage to the fans, ensuring they are always fully loaded for heat dissipation. This ensures system safety and stability under high-temperature conditions. While this saturated operating mode satisfies temperature control requirements, it lacks intelligent adjustment capabilities, manifesting in the following aspects: The fan speed is not adjustable and always runs at a fixed speed. It cannot dynamically adjust the cooling capacity according to changes in system load or when entering sleep mode, resulting in operating efficiency mismatch; the fan runs at a constant high speed for a long time, increasing mechanical wear and thus limiting the fan's service life; even if the system load is low, the fan continues to run at high power, resulting in increased overall energy consumption and long-term high noise.

[0003] Currently, no effective solutions have been proposed for the problems in related technologies. Summary of the Invention

[0004] (1) Technical problems solved In response to the shortcomings of the existing technology, the present invention provides a DC fan automatic voltage conversion speed regulation system, which has the advantage of dynamically controlling the fan speed by automatically adjusting the DC fan input voltage, thereby solving the problem that traditional fan speed regulation systems lack intelligent adjustment capabilities.

[0005] (2) Technical solution In order to achieve the above advantages of dynamically controlling the fan speed by automatically adjusting the DC fan input voltage, the specific technical solutions adopted by the present invention are as follows: A DC fan automatic voltage conversion and speed regulation system, the system includes a DC-DC unit, a feedback automatic adjustment unit and a fan speed control unit, wherein the DC-DC unit is electrically connected to the feedback automatic adjustment unit and the fan speed control unit in sequence; The DC-DC unit is used to achieve DC-DC power conversion with adjustable output voltage over a wide input voltage range. a feedback automatic adjustment unit, configured to collect the output voltage of the DC-DC unit and compare it with the control variable input from the fan speed control unit to obtain an error signal, and adjust the output voltage of the DC-DC unit based on the error signal; The fan speed control unit is used to generate a control voltage based on temperature detection or pulse signal conditioning, and use the control voltage as a control quantity to drive the feedback automatic adjustment unit to achieve automatic or active control of the DC fan speed.

[0006] Preferably, collecting the output voltage of the DC-DC unit and comparing it with the control amount input from the fan speed control unit to obtain an error signal, and adjusting the output voltage of the DC-DC unit based on the error signal includes: Sampling the output voltage of the DC-DC unit, and inputting the sampled output voltage into the first pin of the operational amplifier in the feedback automatic adjustment unit after signal conditioning; The control quantity of the fan speed control unit is input to the third pin of the operational amplifier, and the output voltage is compared with the control quantity by the operational amplifier to obtain an error signal; Based on the error signal, a feedback regulation network formed by a plurality of capacitors and resistors is driven to regulate the output voltage of the DC-DC unit through the feedback regulation network, and the speed of the DC fan is regulated according to the output voltage.

[0007] Preferably, adjusting the speed of the DC fan according to the output voltage includes: When the output voltage increases, the DC fan speed increases; when the output voltage decreases, the DC fan speed decreases.

[0008] Preferably, the fan speed control unit includes a temperature detection module, a reference voltage module and a pulse signal conditioning module, and the temperature detection module is electrically connected to the reference voltage module and the pulse signal conditioning module in sequence; The temperature detection module is used to generate a control voltage signal based on the temperature characteristics of the thermistor, and input the control voltage signal as a control quantity to the feedback automatic adjustment unit; A reference voltage module is used to provide a reference voltage for the temperature detection module; The pulse signal conditioning module is used to process the pulse signal to obtain a reference voltage.

[0009] Preferably, the thermal element is a negative temperature coefficient thermistor.

[0010] Preferably, generating a control voltage signal based on the temperature characteristics of the thermistor and inputting the control voltage signal as a control variable into the feedback automatic adjustment unit includes: When the temperature rises, the resistance of the negative temperature coefficient thermistor decreases, and the voltage output to the control quantity increases. At the same time, the output voltage of the DC-DC unit increases, and the speed of the DC fan increases. When the temperature drops, the resistance of the negative temperature coefficient thermistor increases, and the voltage output to the control quantity decreases. At the same time, the output voltage of the DC-DC unit decreases, and the speed of the DC fan decreases.

[0011] Preferably, when the temperature rises, the resistance of the negative temperature coefficient thermistor decreases, the voltage output to the control quantity increases, and the output voltage of the DC-DC unit increases. The DC fan speed is increased, including: When the temperature rises, the resistance of the negative temperature coefficient thermistor decreases, and the control voltage output by the temperature detection module increases; when the control voltage increases, the fourth pin of the operational amplifier in the feedback automatic adjustment unit dynamically decreases, the on-resistance of the field effect tube dynamically increases, the base current of the transistor dynamically decreases, and the on-resistance of the loop composed of the transistor and one of the resistors increases, so that the output voltage of the DC-DC unit increases and the speed of the DC fan increases.

[0012] Preferably, when the temperature decreases, the resistance of the negative temperature coefficient thermistor increases, the voltage output to the control quantity decreases, and at the same time, the output voltage of the DC-DC unit decreases, and the speed of the DC fan decreases, including: When the temperature drops, the resistance of the negative temperature coefficient thermistor increases, and the control voltage output by the temperature detection module decreases; when the control voltage decreases, the fourth pin of the operational amplifier in the feedback automatic adjustment unit is dynamically increased, the on-resistance of the field effect tube is dynamically reduced, the base current of the transistor is dynamically increased, and the on-resistance of the loop composed of the transistor and one of the resistors is reduced, so that the output voltage of the DC-DC unit decreases and the speed of the DC fan decreases.

[0013] Preferably, processing the pulse signal to obtain the reference voltage includes: Based on the duty cycle of the pulse signal, the pulse signal is filtered and smoothed to obtain a reference voltage which is input into the feedback automatic adjustment unit.

[0014] Preferably, the fifth pin of the chip in the DC-DC unit serves as a feedback input pin of the output voltage of the DC-DC unit; When the on-resistance of the loop formed by the transistor and one of the resistors increases, the feedback input voltage of the fifth pin of the chip in the DC-DC unit decreases, and at the same time the output voltage of the DC-DC unit increases, and the speed of the DC fan increases; when the on-resistance of the loop formed by the transistor and one of the resistors decreases, the feedback input voltage of the fifth pin of the chip in the DC-DC unit increases, and at the same time the output voltage of the DC-DC unit decreases, and the speed of the DC fan decreases.

[0015] (3) Beneficial effects Compared with the prior art, the present invention provides a DC fan automatic voltage conversion and speed regulation system, which has the following beneficial effects: (1) The present invention realizes dynamic control of the fan speed by automatically adjusting the DC fan input voltage. It can not only realize automatic or active speed regulation mode according to temperature changes or external PWM signals, thereby improving the system's adaptability to different working conditions, but also make the fan compatible with a wider range of power supply voltages, thereby enhancing the flexibility and stability of the overall system.

[0016] (2) The present invention can adjust the fan speed in real time according to the thermal load, and automatically reduce the speed or shut down when the system load is low or in sleep mode, thereby achieving intelligent temperature control and reducing unnecessary energy consumption and noise output, effectively improving the system energy efficiency ratio; in addition, the fan operates in a non-full load state for a long time, significantly reducing mechanical wear and thermal aging, extending the bearing life, and reducing maintenance frequency and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a principle block diagram of a DC fan automatic voltage conversion and speed regulation system according to an embodiment of the present invention; Figure 2 1 is a circuit diagram of a DC-DC unit and a feedback automatic adjustment unit in a DC fan automatic voltage conversion and speed regulation system according to an embodiment of the present invention; Figure 3 is a circuit diagram of a temperature detection module in a DC fan automatic voltage conversion and speed regulation system according to an embodiment of the present invention; Figure 4 is a circuit diagram of a reference voltage module in a DC fan automatic voltage conversion and speed regulation system according to an embodiment of the present invention; Figure 5 The present invention is a circuit diagram of a pulse signal conditioning module in a DC fan automatic voltage conversion and speed regulation system according to an embodiment of the present invention.

[0019] In the picture: 1. DC-DC unit; 2. Feedback automatic adjustment unit; 3. Fan speed control unit; 301. Temperature detection module; 302. Reference voltage module; 303. Pulse signal conditioning module. DETAILED DESCRIPTION

[0020] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention. They are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. By referring to these contents, ordinary technicians in this field should be able to understand other possible implementation methods and the advantages of the present invention.

[0021] According to an embodiment of the present invention, a DC fan automatic voltage conversion and speed regulation system is provided.

[0022] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. Figure 1As shown, according to an embodiment of the present invention, the DC fan automatic voltage conversion and speed regulation system includes a DC-DC unit 1, a feedback automatic adjustment unit 2 and a fan speed control unit 3, and the DC-DC unit 1 is electrically connected to the feedback automatic adjustment unit 2 and the fan speed control unit 3 in sequence.

[0023] The DC-DC unit 1 is used to realize DC-DC power conversion with adjustable output voltage under a wide input voltage range.

[0024] Specifically, such as Figure 2 As shown, the DC-DC unit 1 includes a chip U2, a capacitor C7, a capacitor C10, a capacitor C8, a capacitor C14, a resistor R14, a capacitor C13, a resistor R15, an inductor L1, a resistor R17, a capacitor C18, a capacitor C11, a capacitor C15, a capacitor C9 and a DC fan F1; Among them, the first pin of the chip U2 is connected to one end of the capacitor C13, the other end of the capacitor C16 is respectively connected to the inductor L1 and the second pin of the chip U2, the other end of the inductor L1 is respectively connected to one end of the capacitor C11, one end of the capacitor C15, one end of the capacitor C9, one end of the resistor R17, one end of the capacitor C18 and the first pin of the DC fan F1 and connected to V-OUT, the other end of the resistor R17 is respectively connected to the other end of the capacitor C18, one end of the resistor R15, the fifth pin of the chip U2 and the feedback automatic adjustment unit 22, and the other end of the resistor R15 is respectively connected to the capacitor C14. One end is connected and grounded, the other end of capacitor C14 is connected to the fourth pin of chip U2, the second pin of DC fan F1 is respectively connected to the other end of capacitor C11, the other end of capacitor C15, the other end of capacitor C9, one end of capacitor C8, and one end of capacitor C10 and grounded, the other end of capacitor C10 is connected to the other end of capacitor C8, the seventh pin and the eighth pin of chip U2 and connected to VIN, the third pin of chip U2 is connected to one end of resistor R14, the other end of resistor R14 is connected to VIN, the sixth pin of chip U2 is connected to one end of capacitor C7, and the other end of capacitor C7 is grounded.

[0025] The feedback automatic adjustment unit 2 is used to collect the output voltage of the DC-DC unit 1 and compare it with the control quantity input from the fan speed control unit 3 to obtain an error signal, and adjust the output voltage of the DC-DC unit 1 based on the error signal.

[0026] The output voltage of the DC-DC unit 1 is collected and compared with the control amount input from the fan speed control unit 3 to obtain an error signal, and the output voltage of the DC-DC unit 1 is adjusted based on the error signal, including: Sampling the output voltage of the DC-DC unit 1, and inputting the sampled output voltage into the first pin of the operational amplifier in the feedback automatic adjustment unit 2 after signal conditioning; The control value of the fan speed control unit 3 is input to the third pin of the operational amplifier, and the output voltage is compared with the control value by the operational amplifier to obtain an error signal; Based on the error signal, a feedback regulation network formed by a plurality of capacitors and resistors is driven to regulate the output voltage of the DC-DC unit 1 through the feedback regulation network, and the speed of the DC fan is regulated according to the output voltage.

[0027] Wherein, adjusting the speed of the DC fan according to the output voltage includes: When the output voltage increases, the DC fan speed increases; when the output voltage decreases, the DC fan speed decreases.

[0028] Specifically, such as Figure 2 As shown, the feedback automatic adjustment unit 22 includes: an operational amplifier U1, a transistor Q1, a resistor R1, a resistor R2, a resistor R4, a resistor R13, a capacitor C1, a resistor R8, a capacitor C2, a field effect transistor Q2, a resistor R5, a diode D1, a capacitor C17, a resistor R6, a resistor R7, a resistor R9, a capacitor C3 and a resistor R11; The first pin of the operational amplifier U1 is respectively connected to one end of the capacitor C2, one end of the capacitor C1, and one end of the resistor R6. The other end of the capacitor C1 is respectively connected to one end of the resistor R8, one end of the resistor R4, and the drain of the field effect transistor Q2. The other end of the resistor R8 is connected to the other end of the capacitor C2. The other end of the resistor R4 is respectively connected to one end of the resistor R2, the base of the transistor Q1, and one end of the resistor R13. The other end of the resistor R13 is connected to the collector of the transistor Q1 and the fifth pin of the chip U2. The emitter of the transistor Q1 is connected to one end of the resistor R1. The other end of the resistor R1 is respectively connected to the other end of the resistor R2 and one end of the resistor R9 and is connected to V-OUT. The other end of R9 is respectively connected to one end of resistor R11, one end of capacitor C3, and the other end of resistor R6. The other end of resistor R11 is connected to the other end of capacitor C3 and to ground. The second pin of operational amplifier U1 is grounded. The third pin of operational amplifier U1 is connected to one end of resistor R7. The other end of resistor R7 is connected to Ref. The fourth pin of operational amplifier U1 is connected to one end of resistor R5. The other end of resistor R5 is connected to the gate of field effect transistor Q2 and the cathode of diode D1. The anode of diode D1 is connected to the source of field effect transistor Q2 and to ground. The fifth pin of operational amplifier U1 is connected to one end of capacitor C17 and to VIN. The other end of capacitor C17 is grounded.

[0029] The fan speed control unit 3 is used to generate a control voltage based on temperature detection or pulse signal conditioning, and use the control voltage as a control quantity to drive the feedback automatic adjustment unit 2 to achieve automatic or active control of the DC fan speed.

[0030] Specifically, the wind speed control methods include: temperature sensor adjustment; main control PWM adjustment to achieve multiple gears; potentiometer adjustment.

[0031] The fan speed control unit 3 includes a temperature detection module 301, a reference voltage module 302 and a pulse signal conditioning module 303, and the temperature detection module 301 is electrically connected to the reference voltage module 302 and the pulse signal conditioning module 303 in sequence; The temperature detection module 301 is used to generate a control voltage signal based on the temperature characteristics of the thermistor, and input the control voltage signal as a control variable to the feedback automatic adjustment unit 2.

[0032] The thermistor is a negative temperature coefficient thermistor. A control voltage signal is generated based on the temperature characteristics of the thermistor, and the control voltage signal is input as a control quantity to the feedback automatic adjustment unit 2. When the temperature rises, the resistance of the negative temperature coefficient thermistor decreases, and the voltage output to the control quantity increases. At the same time, the output voltage of the DC-DC unit 1 increases, and the speed of the DC fan increases.

[0033] When the temperature rises, the resistance of the negative temperature coefficient thermistor decreases, and the voltage output to the control quantity increases. At the same time, the output voltage of the DC-DC unit 1 increases, and the speed of the DC fan increases. The following steps are involved: When the temperature rises, the resistance of the negative temperature coefficient thermistor decreases, and the control voltage output by the temperature detection module 301 increases; When the control voltage increases, the fourth pin of the operational amplifier in the feedback automatic adjustment unit 2 is caused to dynamically decrease, the on-resistance of the field effect tube is dynamically increased, the base current of the transistor is dynamically reduced, and the on-resistance of the loop composed of the transistor and one of the resistors is increased, so that the output voltage of the DC-DC unit 1 increases and the speed of the DC fan is increased.

[0034] When the temperature drops, the resistance of the negative temperature coefficient thermistor increases, and the voltage output to the control quantity decreases. At the same time, the output voltage of the DC-DC unit 1 decreases, and the speed of the DC fan decreases.

[0035] When the temperature decreases, the resistance of the negative temperature coefficient thermistor increases, and the voltage output to the control quantity decreases. At the same time, the output voltage of the DC-DC unit 1 decreases, and the speed of the DC fan decreases. When the temperature drops, the resistance of the negative temperature coefficient thermistor increases, and the control voltage output by the temperature detection module 301 decreases. When the control voltage decreases, the fourth pin of the operational amplifier in the feedback automatic adjustment unit 2 is dynamically increased, the on-resistance of the field effect transistor is dynamically reduced, the base current of the transistor is dynamically increased, and the on-resistance of the loop formed by the transistor and one of the resistors is reduced, so that the output voltage of the DC-DC unit 1 decreases and the speed of the DC fan decreases.

[0036] Among them, the fifth pin of the chip in the DC-DC unit 1 serves as the feedback input pin of the output voltage of the DC-DC unit 1; when the on-resistance of the loop composed of the transistor and one of the resistors increases, the feedback input voltage of the fifth pin of the chip in the DC-DC unit 1 decreases, and at the same time the output voltage of the DC-DC unit 1 increases, and the speed of the DC fan increases; when the on-resistance of the loop composed of the transistor and one of the resistors decreases, the feedback input voltage of the fifth pin of the chip in the DC-DC unit 1 increases, and at the same time the output voltage of the DC-DC unit 1 decreases, and the speed of the DC fan decreases.

[0037] Specifically, such as Figure 3 As shown, the temperature detection module 301 includes a thermistor R12, a resistor R10 and a capacitor C5; One end of the thermistor R12 is connected to 3.3 VREF, the other end of the thermistor R12 is connected to one end of the resistor R10 and one end of the capacitor C5 and to Ref, and the other end of the resistor R10 is connected to the other end of the capacitor C5 and to ground.

[0038] The reference voltage module 302 is configured to provide a reference voltage for the temperature detection module 301 .

[0039] Specifically, such as Figure 4 As shown, the reference voltage module 302 includes a capacitor C12, a diode U3, a resistor R16, a resistor R18, a resistor R19 and a capacitor C16; One end of capacitor C12 is connected to one end of resistor R16 and to VIN. The other end of resistor R16 is respectively connected to one end of resistor R18, the cathode of diode U3, and one end of capacitor C16 and to 3.3VREF. The other end of capacitor C12 is respectively connected to the anode of diode U3, one end of resistor R19, the other end of capacitor C16 and to ground. The other end of resistor R19 is connected to the other end of resistor R18.

[0040] The pulse signal conditioning module 303 is used to process the pulse signal to obtain a reference voltage, wherein the pulse signal is filtered and smoothed based on the duty cycle of the pulse signal to obtain the reference voltage and input it into the feedback automatic adjustment unit 2.

[0041] Specifically, such as Figure 5As shown, the pulse signal conditioning module 303 (equivalent to the PWM input signal conditioning circuit) includes a resistor R3, a capacitor C4 and a capacitor C6; One end of the resistor R3 is connected to the PWM signal, the other end of the resistor R3 is connected to one end of the capacitor C4 and the capacitor C6 and to Ref, and the other end of the capacitor C4 is connected to the other end of the capacitor C6 and is grounded.

[0042] In order to facilitate understanding of the above technical solutions of the present invention, the working principle or operation mode of the present invention in actual process is described in detail below.

[0043] In practical application, the present invention consists of a DC-DC unit 1 with a wide input voltage range and adjustable output voltage, a feedback automatic adjustment unit 2 and a fan speed control unit 3, wherein the fan speed control unit 3 includes a temperature detection module 301, a reference voltage module 302 and a pulse signal conditioning module 303.

[0044] Specifically, the wide input voltage range and output voltage adjustable DC-DC unit 1 of chip U2 mainly realizes DC-DC power conversion with adjustable output voltage, and its models or types include but are not limited to Figure 2 The fifth pin of chip U2 is the feedback input pin of the output voltage of DC-DC unit 1. F1 is a DC fan connected to the output of DC-DC unit 1.

[0045] Operational amplifier U1 comprises feedback auto-regulation unit 2, with resistor R1, transistor Q1, and resistor R17 connected in parallel. U1 is an operational amplifier. Resistors R9 and R11 in feedback auto-regulation unit 2 sample the voltage from the output of chip U2, which is then input to pin 1 of operational amplifier U1 after signal conditioning. Pin 3 of operational amplifier U1 is the control input pin, connected to temperature detection module 301, which consists of resistors R12, R10, and capacitor C5. Resistor R12 is a negative temperature coefficient (NTC) resistor, whose resistance decreases as temperature rises. The control input pin can also be connected to pulse signal conditioning module 303 (PWM input signal conditioning circuit), which consists of resistors R3, C4, and C6. This generates a stable reference voltage through filtering and smoothing by capacitors C4 and C6, based on the PWM duty cycle. Capacitor C1, resistor R8, and capacitor C2 form a feedback regulation network that regulates FET Q2 and transistor Q1, thereby adjusting the feedback input of chip U2 and regulating the output voltage of chip U2. The DC fan will change its speed according to the voltage. Section U3 is the reference voltage module 302, which provides a reference voltage for the temperature detection module 301 composed of capacitor R12, resistor R10, and capacitors.

[0046] 1. When the temperature rises: the resistance of thermistor R12 decreases, the control quantity Ref voltage increases, the fourth pin of operational amplifier U1 dynamically decreases, the gate voltage of field effect transistor Q2 becomes lower, the on-resistance of field effect transistor Q2 dynamically increases, the base current of transistor Q1 (the transistor is a PNP transistor) dynamically decreases, the on-resistance of the resistor R1 and transistor Q1 loop increases, the voltage feedback input voltage of the fifth pin of chip U2 becomes lower instantly, and chip U2 dynamically adjusts to increase the V-OUT output voltage. As the output voltage increases, the fan speed increases.

[0047] 2. When the temperature drops: the resistance of thermistor R12 increases, the control quantity Ref voltage decreases, the fourth pin of operational amplifier U1 increases dynamically, the gate voltage of field effect transistor Q2 becomes higher, the on-resistance of field effect transistor Q2 decreases dynamically, the base current of transistor Q1 (the transistor is a PNP transistor) increases dynamically, the on-resistance of resistor R1 and transistor Q1 loop decreases dynamically, the voltage feedback input voltage of the fifth pin of chip U2 increases instantaneously, and chip U2 dynamically adjusts to reduce the V-OUT output voltage. As the output voltage decreases, the fan speed decreases.

[0048] In summary, with the help of the above-mentioned technical solution of the present invention, the present invention realizes dynamic control of the fan speed by automatically adjusting the DC fan input voltage, which can not only realize automatic or active speed regulation mode according to temperature changes or external PWM signals, thereby improving the system's adaptability to different working conditions, but also make the fan compatible with a wider range of power supply voltages, thereby enhancing the flexibility and stability of the overall system; the present invention can adjust the fan speed in real time according to the thermal load, and automatically reduce the speed or shut down when the system load is low or in sleep state, thereby realizing intelligent temperature control and reducing unnecessary energy consumption and noise output, effectively improving the system energy efficiency ratio; in addition, the fan works in a non-full load state for a long time, which significantly reduces mechanical wear and thermal aging, extends the bearing life, and reduces maintenance frequency and cost.

[0049] In the present invention, unless otherwise clearly stipulated and limited, the terms "install", "set", "connect", "fix", "screw" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A DC fan automatic voltage conversion and speed regulation system, characterized in that: The system includes a DC-DC unit, a feedback automatic adjustment unit and a fan speed control unit, and the DC-DC unit is electrically connected to the feedback automatic adjustment unit and the fan speed control unit in sequence; Wherein, the DC-DC unit is used to realize DC-DC power conversion with adjustable output voltage under a wide input voltage range; The feedback automatic adjustment unit is used to collect the output voltage of the DC-DC unit and compare it with the control amount input from the fan speed control unit to obtain an error signal, and adjust the output voltage of the DC-DC unit based on the error signal; The fan speed control unit is used to generate a control voltage based on temperature detection or pulse signal conditioning, and use the control voltage as a control variable to drive the feedback automatic adjustment unit to achieve automatic or active control of the DC fan speed.

2. A DC fan automatic voltage conversion and speed regulation system according to claim 1, characterized in that: The collecting the output voltage of the DC-DC unit and comparing it with the control amount input from the fan speed control unit to obtain an error signal, and adjusting the output voltage of the DC-DC unit based on the error signal includes: Sampling the output voltage of the DC-DC unit, and inputting the sampled output voltage into the first pin of the operational amplifier in the feedback automatic adjustment unit after signal conditioning; Inputting the control quantity of the fan speed control unit into the third pin of the operational amplifier, and comparing the output voltage with the control quantity through the operational amplifier to obtain an error signal; A feedback regulation network formed by a plurality of capacitors and resistors is driven based on the error signal, the output voltage of the DC-DC unit is regulated through the feedback regulation network, and the speed of the DC fan is regulated according to the output voltage.

3. The DC fan automatic voltage conversion and speed regulation system according to claim 2, characterized in that: The step of adjusting the DC fan speed according to the output voltage includes: When the output voltage increases, the DC fan speed increases; when the output voltage decreases, the DC fan speed decreases.

4. The DC fan automatic voltage conversion and speed regulation system according to claim 1, characterized in that: The fan speed control unit includes a temperature detection module, a reference voltage module and a pulse signal conditioning module, and the temperature detection module is electrically connected to the reference voltage module and the pulse signal conditioning module in sequence; The temperature detection module is used to generate a control voltage signal based on the temperature characteristics of the thermistor, and input the control voltage signal as a control variable into the feedback automatic adjustment unit; The reference voltage module is used to provide a reference voltage for the temperature detection module; The pulse signal conditioning module is used to process the pulse signal to obtain a reference voltage.

5. The DC fan automatic voltage conversion and speed regulation system according to claim 4, characterized in that: The thermal element is a negative temperature coefficient thermistor.

6. The DC fan automatic voltage conversion and speed regulation system according to claim 5, characterized in that: Generating a control voltage signal based on the temperature characteristics of the thermistor and inputting the control voltage signal as a control variable into the feedback automatic adjustment unit includes: When the temperature rises, the resistance of the negative temperature coefficient thermistor decreases, and the voltage output to the control quantity increases. At the same time, the output voltage of the DC-DC unit increases, and the speed of the DC fan increases; When the temperature drops, the resistance of the negative temperature coefficient thermistor increases, and the voltage output to the control quantity decreases. At the same time, the output voltage of the DC-DC unit decreases, and the speed of the DC fan decreases.

7. The DC fan automatic voltage conversion and speed regulation system according to claim 6, characterized in that: When the temperature rises, the resistance of the negative temperature coefficient thermistor decreases, the voltage output to the control quantity increases, and at the same time, the output voltage of the DC-DC unit increases, and the speed of the DC fan increases, which includes: When the temperature rises, the resistance of the negative temperature coefficient thermistor decreases, and the control voltage output by the temperature detection module increases; When the control voltage increases, the fourth pin of the operational amplifier in the feedback automatic adjustment unit is caused to dynamically decrease, the on-resistance of the field effect transistor is dynamically increased, the base current of the transistor is dynamically reduced, and the on-resistance of the loop composed of the transistor and one of the resistors is increased, so that the output voltage of the DC-DC unit is increased and the speed of the DC fan is increased.

8. The DC fan automatic voltage conversion and speed regulation system according to claim 7, characterized in that: When the temperature decreases, the resistance of the negative temperature coefficient thermistor increases, the voltage output to the control quantity decreases, and at the same time, the output voltage of the DC-DC unit decreases, and the speed of the DC fan decreases, which includes: When the temperature drops, the resistance of the negative temperature coefficient thermistor increases, and the control voltage output by the temperature detection module decreases; When the control voltage decreases, the fourth pin of the operational amplifier in the feedback automatic adjustment unit is dynamically increased, the on-resistance of the field effect transistor is dynamically reduced, the base current of the transistor is dynamically increased, and the on-resistance of the loop composed of the transistor and one of the resistors is reduced, so that the output voltage of the DC-DC unit is reduced and the speed of the DC fan is reduced.

9. The DC fan automatic voltage conversion and speed regulation system according to claim 8, characterized in that: The processing of the pulse signal to obtain the reference voltage includes: Based on the duty cycle of the pulse signal, the pulse signal is filtered and smoothed to obtain a reference voltage which is input into the feedback automatic adjustment unit.

10. The DC fan automatic voltage conversion and speed regulation system according to claim 9, characterized in that: The fifth pin of the chip in the DC-DC unit serves as a feedback input pin of the output voltage of the DC-DC unit; When the loop conduction impedance increases, the feedback input voltage of the fifth pin of the chip in the DC-DC unit decreases, while the output voltage of the DC-DC unit increases, and the speed of the DC fan increases; When the loop conduction impedance decreases, the feedback input voltage of the fifth pin of the chip in the DC-DC unit increases, while the output voltage of the DC-DC unit decreases and the speed of the DC fan decreases.

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