Fan speed measuring device

Abstract

The utility model discloses a fan speed measuring device. Dependence on the capturing function of a single-chip microcomputer is avoided. The fan speed measuring device comprises a Hall sensor, a monostable trigger, a first resistance circuit and a Buck circuit, the output positive electrode of the Hall sensor is connected with one end of the first resistance circuit, and the output negative electrode of the Hall sensor is grounded; the other end of the first resistance circuit is connected with a power supply and is connected with a trigger input pin of the monostable trigger; the frequency of the pulse signal output by the Hall sensor is in positive correlation with the rotating speed of the fan; the output end of the monostable trigger is connected with the gate pole of a switching tube in the Buck circuit; the input end of the Buck circuit is connected with a power supply; and when the monostable trigger triggers the input pin to receive a rising edge signal, the monostable trigger switches from low level output to high level output and maintains the high level output, and when the maintaining time of the high level output reaches a preset time, the monostable trigger switches back to the low level output.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and particularly to a fan speed measurement device. Background Art

[0002] Fan speed measurement refers to the process of measuring the rotational speed of a fan. The Hall speed measurement method is a commonly used fan speed measurement method. This method is based on the Hall effect principle. By using a Hall sensor, the periodic change of the magnetic field during the rotation of the fan can be accurately sensed. Whenever the magnetic field changes once, the Hall sensor outputs a pulse signal. There is a dedicated capture module in the single-chip microcomputer to capture the number of pulses generated by the Hall sensor within a certain period of time, and based on the corresponding relationship between the number of pulses and the fan speed, the real-time speed of the fan is calculated.

[0003] However, this method needs to rely on the capture function of the single-chip microcomputer, so it cannot be applied to a wider range of single-chip microcomputer models and scenarios. Utility Model Content

[0004] In view of the above problems, this application provides a fan speed measurement device to avoid relying on the capture function of the single-chip microcomputer. The specific solution is as follows:

[0005] This application provides a fan speed measurement device, including: a Hall sensor, a monostable flip-flop, a first resistor circuit, and a Buck circuit;

[0006] Wherein, the positive output terminal of the Hall sensor is connected to one end of the first resistor circuit, and the negative output terminal of the Hall sensor is grounded;

[0007] The other end of the first resistor circuit is connected to the power supply and is also connected to the trigger input pin of the monostable flip-flop;

[0008] The frequency of the pulse signal output by the Hall sensor is positively correlated with the rotational speed of the fan;

[0009] The output terminal of the monostable flip-flop is connected to the gate of the switching tube in the Buck circuit; the input terminal of the Buck circuit is connected to the power supply;

[0010] The monostable flip-flop is used to switch from a low-level output to a high-level output and maintain it when a rising edge signal is received at the trigger input pin. When the holding time of the high-level output reaches a preset time, it switches back to the low-level output.

[0011] In a possible implementation, the monostable flip-flop is replaced with: when a falling edge signal is received at the trigger input pin, it switches from a low-level output to a high-level output and maintains it. When the holding time of the high-level output reaches a preset time, it switches back to the low-level output;

[0012] The fan speed measurement device further includes: an inverter connected between the second end of the first resistor circuit and the trigger input pin of the monostable flip-flop.

[0013] In a possible implementation, the monostable flip-flop is replaced with: when a rising edge signal is received at the trigger input pin, it switches from a high-level output to a low-level signal and holds, and when the holding time of the low-level signal reaches a preset time, it switches back to a high-level output;

[0014] The fan speed measurement device further includes: an inverter connected between the output end of the monostable flip-flop and the gate of the switching tube.

[0015] In a possible implementation, the monostable flip-flop is replaced with: when a falling edge signal is received at the trigger input pin, it switches from a high-level output to a low-level signal and holds, and when the holding time of the low-level signal reaches a preset time, it switches back to a high-level output;

[0016] The fan speed measurement device further includes: an inverter connected between the second end of the first resistor circuit and the trigger input pin of the monostable flip-flop, and an inverter connected between the output end of the monostable flip-flop and the gate of the switching tube.

[0017] In a possible implementation, the switching tube is installed on the negative side of the Buck circuit.

[0018] In a possible implementation, the switching tube is a MOSFET or a triode.

[0019] In a possible implementation, the fan speed measurement device further includes: a second resistor circuit, and the second resistor circuit is connected in parallel with the capacitor in the Buck circuit.

[0020] In a possible implementation, the fan speed measurement device further includes: a differential operational amplifier; the first input terminal of the differential operational amplifier is connected to the high-voltage terminal of the capacitor in the Buck circuit, the second input terminal of the differential operational amplifier is connected to the low-voltage terminal of the capacitor, and the output terminal of the differential operational amplifier is used to access the analog-to-digital converter port of the single-chip microcomputer.

[0021] In a possible implementation, the differential operational amplifier includes an operational amplifier, a third resistor circuit, a fourth resistor circuit, and a fifth resistor circuit;

[0022] The non-inverting input terminal of the operational amplifier is connected to one end of the third resistor circuit, and the other end of the third resistor circuit serves as the first input terminal of the differential operational amplifier;

[0023] The inverting input terminal of the operational amplifier is connected to one end of the fourth resistor circuit, and the other end of the fourth resistor circuit serves as the second input terminal of the differential operational amplifier;

[0024] The fifth resistor circuit is connected between the inverting input terminal and the output terminal of the operational amplifier;

[0025] The output terminal of the operational amplifier serves as the output terminal of the differential operational amplifier.

[0026] In a possible implementation, the Hall sensor is installed on the motor of the fan.

[0027] By means of the above technical solution, the fan speed measurement device provided by the present application can convert the pulse signal output by the Hall sensor into a voltage analog quantity. Specifically: the faster the fan speed, the higher the frequency of the pulse signal output by the Hall sensor, and thus the larger the duty cycle of the pulse signal output by the monostable flip-flop, and further the longer the conduction time of the switching tube relative to the turn-off time, and further the higher the voltage of the capacitor in the Buck circuit. There is a fixed positive correlation between the voltage of this capacitor and the fan speed. Therefore, only by measuring this analog quantity of the voltage of this capacitor can the fan speed be calculated. The voltage analog quantity can be directly measured with a multimeter and does not rely on the capture function of the single-chip microcomputer. Therefore, this device can be applied to a wider range of single-chip microcomputer models and scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Combined with the drawings and referring to the following specific embodiments, the above and other features, advantages and aspects of the various embodiments of the present disclosure will become more obvious. Throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the original components and elements are not necessarily drawn to scale.

[0029] Figure 1 It is a schematic diagram of a fan speed measurement device provided by the present application;

[0030] Figure 2 It is a schematic diagram of the change curves of the fan speed, the output level of the Hall sensor, and the output level of the monostable flip-flop over time provided by the present application;

[0031] Figure 3 It is a schematic diagram of another fan speed measurement device provided by the present application;

[0032] Figure 4 It is a schematic diagram of another fan speed measurement device provided by the present application;

[0033] Figure 5 It is a schematic diagram of another fan speed measurement device provided by the present application;

[0034] Figure 6Schematic diagram of another fan speed measurement device provided by this application;

[0035] Figure 7 Schematic diagram of another fan speed measurement device provided by this application;

[0036] Figure 8 Schematic diagram of another fan speed measurement device provided by this application. Detailed implementation

[0037] In the following description, to ensure the accuracy of citations and the fluency of reading, the key technical terms, abbreviations or acronyms involved in the text are summarized and explained as follows:

[0038] DSP: Digital Signal Processor, digital signal processor;

[0039] ARM: Advanced RISC Machine, advanced reduced instruction set machine;

[0040] Buck circuit: buck chopper circuit;

[0041] RC network: resistor-capacitor network;

[0042] MOSFET: Metal-Oxide-Semiconductor Field-Effect Transistor, metal oxide semiconductor field effect transistor;

[0043] ADC: Analog to Digital Converter, analog-to-digital converter.

[0044] Fan speed measurement refers to the process of measuring the rotational speed of a fan, which is an important means to evaluate the performance of a fan, ensure its normal operation, and conduct fault prediction and maintenance. In many fields such as aerospace, energy generation, and industrial manufacturing, fan speed measurement plays a crucial role.

[0045] Taking the aerospace field as an example, the fans used in this field, such as engine cooling fans and environmental control system fans, the precise control of their rotational speeds is directly related to the performance and safety of the aircraft. Therefore, precise fan speed measurement is of extremely important significance for ensuring the stable operation of the aircraft. Through speed measurement, the rotational speed changes of the fan can be monitored in real time, any potential fault hazards can be detected in a timely manner, and then necessary maintenance or replacement measures can be taken to ensure the overall safety of the aircraft.

[0046] Hall speed measurement method is a commonly used method for measuring the speed of a fan. Briefly speaking, this method is based on the principle of Hall effect. By using a Hall sensor, it can accurately sense the periodic changes of the magnetic field during the rotation of the fan. Every time the magnetic field changes, the Hall sensor outputs a pulse signal. By accumulating the number of these pulse signals and according to the corresponding relationship between the number of pulses and the fan speed, the real-time speed of the fan can be calculated.

[0047] To facilitate a deeper understanding of the Hall speed measurement method, its working principle is introduced in detail as follows:

[0048] The Hall effect is an electromagnetic phenomenon. When an electric current passes through a conductor placed in a magnetic field, an electric potential difference (i.e., Hall voltage) will be generated in the direction perpendicular to both the current and the magnetic field. The Hall sensor utilizes this principle to convert the change of the magnetic field into a measurable electrical signal. In the fan speed measurement, a magnet is fixed on the rotating shaft of the fan. As the fan rotates, the magnet on the rotating shaft also rotates. During this rotation process, the direction and intensity of the magnetic field of the magnet will change periodically relative to the Hall sensor fixed nearby. Under standard operating conditions, every time a magnetic pole (either the N pole or the S pole) of the magnet rotates to the position opposite to the Hall sensor, the Hall sensor can sensitively capture the change of the magnetic field of this magnetic pole and output a pulse signal. The generation of this pulse signal is directly related to the number of times the magnetic pole of the magnet passes through the sensor. Therefore, the frequency of the pulse signal is positively correlated with the speed of the fan (when the change directions of two variables are the same, that is, when one variable increases, the other variable also increases; or when one variable decreases, the other variable also decreases, we say that these two variables are positively correlated). In other words, the faster the fan rotates, the more times the magnet rotates past the Hall sensor, and the higher the frequency of the generated pulse signal.

[0049] Traditional fan speed measurement schemes based on the Hall speed measurement method require a dedicated capture module in a microcontroller (such as DSP or ARM, etc.) to capture the number of pulses generated by the Hall sensor within a certain period of time, and calculate the real-time speed of the fan according to the corresponding relationship between the number of pulses and the fan speed.

[0050] Hall sensors have the advantages of non-contact measurement, high sensitivity, fast response, and strong anti-interference ability, so they are very suitable for fan speed measurement. However, this traditional fan speed measurement scheme based on the Hall speed measurement method relies on the capture function of the microcontroller, so it cannot be applied to a wider range of microcontroller models and scenarios.

[0051] To avoid relying on the capture function of the single-chip microcomputer, the embodiment of the present application provides a fan speed measurement device. This device converts the pulse signal output by the Hall sensor into a voltage analog quantity, which can be directly measured with a multimeter. Then, based on the corresponding relationship between the voltage analog quantity and the fan speed, the real-time speed of the fan can be calculated. The entire speed measurement process does not rely on the capture function of the single-chip microcomputer, so it can be applied to a wider range of single-chip microcomputer models and scenarios.

[0052] The following describes in detail a fan speed measurement device provided by the embodiment of the present application with reference to the accompanying drawings. As can be known to those of ordinary skill in the art, with the development of technology and the emergence of new scenarios, the technical solution provided by the embodiment of the present application is equally applicable to similar technical problems.

[0053] The terms "first", "second", etc. in the specification, claims and above-mentioned drawings of the present application are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances, which is only a way of distinguishing objects with the same attributes when describing the embodiments of the present application. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, so that a process, method, system, product or device comprising a series of units does not necessarily have to be limited to those units, but may include other units not clearly listed or inherent to these processes, methods, products or devices.

[0054] See Figure 1 , a fan speed measurement device provided by the embodiment of the present application includes: a Hall sensor U3, a monostable flip-flop U2, a first resistor circuit 100, and a Buck circuit 200;

[0055] Among them, the positive output of the Hall sensor U3 is connected to the first end of the first resistor circuit 100, and the negative output of the Hall sensor U3 is grounded to GND;

[0056] The second end of the first resistor circuit 100 is connected to the power supply Vbat and is also connected to the trigger input pin (abbreviated as pin 1) of the monostable flip-flop U2;

[0057] The installation position of the Hall sensor U3 needs to ensure that the frequency of the pulse signal output by the Hall sensor U3 is positively correlated with the speed of the fan;

[0058] The ground terminal of Hall sensor U3 (abbreviated as pin 5) is grounded to GND; the output terminal of monostable flip-flop U2 (abbreviated as pin 6) is connected to the gate of switching transistor Q1 in Buck circuit 200; the input terminal of Buck circuit 200 is connected to power supply BAT1, that is, the positive input of Buck circuit 200 is connected to the positive pole of power supply BAT1, and the negative input of Buck circuit 200 is connected to the negative pole of power supply BAT1. The negative pole of power supply BAT1 is generally grounded to GND;

[0059] The monostable flip-flop U2 is used to switch from a low-level output to a high-level output and hold when a rising-edge signal is received at the trigger input pin. When the holding time of the high-level output reaches the preset time, it switches back to the low-level output.

[0060] The following details Figure 1 the working principle of the illustrated embodiment:

[0061] When the fan rotates, Hall sensor U3 will periodically detect the magnetic field change generated during the rotation of the fan, and thus output a series of pulse signals with a fixed duty cycle and a frequency positively correlated with the fan speed (such as a square wave signal, and the duty cycle of the square wave signal is 50%. The duty cycle refers to the proportion of the time when the signal is at the high level in a pulse period; the frequency is the reciprocal of the pulse period).

[0062] A monostable flip-flop is a circuit with a stable state (steady state) and a transient state (non-steady state). Its basic structure includes a trigger input terminal, a steady-state output terminal, and a transient-state time control element (usually an RC network). The working principle of a monostable flip-flop with this structure is as follows: when no trigger signal is received at the trigger input terminal, the monostable flip-flop is in the steady state, and at this time the output terminal remains at a fixed level (high level or low level); when a trigger signal that meets the conditions (such as a rising edge, a falling edge, or a signal with a specific level) is received at the trigger input pin, the monostable flip-flop switches from the steady state to the transient state and holds for a period of time, and then automatically returns to the steady state (if the steady state is high level, the transient state is low level; vice versa). The duration of the transient state is determined by the parameter values of the RC network. When the parameter values of the RC network are fixed, the duration of the transient state is a fixed value.

[0063] Figure 2 In the illustrated embodiment, the monostable flip-flop U2 is designed to be triggered by a rising edge, and its steady state is set to low level and the transient state is set to high level. When the monostable flip-flop U2 receives a rising-edge signal at pin 1, it switches from a low-level output to a high-level output and holds for a period of time, and then automatically returns to the low-level output. When the fan speed is getting faster and faster, a series of pulse signals with an increasing frequency are output at pin 6 of the monostable flip-flop U2.

[0064] Since the duration of the monostable flip-flop U2 in the quasi-stable state (high level) is fixed, the pulse width of the pulse signal output from pin 6 of the monostable flip-flop U2 (the pulse width refers to the duration of the high level within a pulse period) remains unchanged. Then, the higher the frequency of the pulse signal output from pin 6, the shorter the duration of the low level of the pulse signal output from pin 6, and thus the larger the duty cycle of the pulse signal output from pin 6.

[0065] For example Figure 2 as shown Figure 2 Among them, the three waveforms from top to bottom respectively represent the curve of the fan speed n changing with time t, the curve of the output level V of the Hall sensor U3 changing with time t, and the curve of the output level V of the monostable flip-flop U2 changing with time t. Obviously, from U3 it can be seen that the frequency of the pulse output by the Hall sensor U3 is positively correlated with the fan speed n, and the frequency and duty cycle of the pulse output by the monostable flip-flop U2 are also positively correlated with the fan speed n. U2 From Figure 2 it can be known that the frequency of the pulse output by the Hall sensor U3 is positively correlated with the fan speed n, and the frequency and duty cycle of the pulse output by the monostable flip-flop U2 are also positively correlated with the fan speed n.

[0066] Pin 6 of the monostable flip-flop U2 is the gate signal of the switching transistor Q1. When the gate signal of the switching transistor Q1 is at a high level, the switching transistor Q1 conducts, and the input voltage of the buck circuit 200 charges the capacitor C1 in the buck circuit 200 through the switching transistor Q1; when the gate signal of the switching transistor Q1 is at a low level, the switching transistor Q1 turns off, and the capacitor C1 starts to discharge. As the duty cycle of the gate signal becomes larger and larger, the voltage of the capacitor C1 becomes higher and higher, that is, the voltage of the capacitor C1 is positively correlated with the duty cycle of the gate signal of the switching transistor Q1.

[0067] In summary, the faster the fan speed, the higher the frequency of the pulse output by the Hall sensor U3, the larger the duty cycle of the pulse output by the monostable flip-flop U2, the longer the conduction time of the switching transistor Q1 relative to the turn-off time, and the higher the voltage of the capacitor C1. There is a clear positive correlation between the voltage of the capacitor C1 and the fan speed. Therefore, by measuring the voltage of the capacitor C1, the fan speed can be calculated. In the embodiment of the present application, the pulse of the Hall sensor U3 is converted into an analog quantity of the voltage of the capacitor C1, and this analog quantity can be directly measured with a multimeter, and then the corresponding fan speed can be calculated, without relying on the capture function of the single-chip microcomputer. Therefore, it can be applied to a wider range of single-chip microcomputer models and scenarios.

[0068] In a possible implementation, the monostable flip-flop U2 in any of the above-provided fan speed measurement devices can also be replaced with other types. For example, when a falling edge signal is received at the trigger input pin, it switches from a low-level output to a high-level signal and remains there. When the holding time of the high-level signal reaches a preset time, it switches back to a low-level output. At the same time, as Figure 3As shown, the fan speed measurement device further includes: an inverter U3 connected between the second end of the first resistor circuit 100 and the trigger input pin of the monostable flip-flop, for inverting the logical state of the inverter input signal, that is: if the input signal is high level, the output signal is low level; conversely, if the input signal is low level, the output signal is high level.

[0069] In a possible implementation, the monostable flip-flop U2 in any of the above-provided fan speed measurement devices can also be replaced with other types. For example, when a rising edge signal is received at the trigger input pin, it switches from a high-level output to a low-level signal and holds. When the holding time of the low-level signal reaches the preset time, it switches back to a high-level output. At the same time, as Figure 4 shown, the fan speed measurement device further includes: an inverter connected between the output end of the monostable flip-flop and the gate of the switching transistor Q1.

[0070] In a possible implementation, the monostable flip-flop U2 in any of the above-provided fan speed measurement devices can also be replaced with other types. For example, when a falling edge signal is received at the trigger input pin, it switches from a high-level output to a low-level signal and holds. When the holding time of the low-level signal reaches the preset time, it switches back to a high-level output. At the same time, as Figure 5 shown, the fan speed measurement device further includes: an inverter connected between the second end of the first resistor circuit 100 and the trigger input pin of the monostable flip-flop, and an inverter connected between the output end of the monostable flip-flop and the gate of the switching transistor Q1.

[0071] For different types of monostable flip-flops, by introducing an inverter, Figures 3 to 5 the same technical effects can be achieved as Figure 1 and will not be elaborated here one by one.

[0072] In a possible implementation, the switching transistor Q1 in the Buck circuit 200 in any of the above-provided fan speed measurement devices can be installed on the positive side or the negative side. Figure 1 、 Figures 2 to 5 Both

[0073] take the switching transistor Q1 installed on the negative side as an example. Figure 1 、 Figures 2 to 5As shown, when the switching transistor Q1 is installed on the negative side, the internal circuit connection relationship of the Buck circuit 200 is as follows: the output pole of the switching transistor Q1 is connected to the negative pole of the power supply BAT1, the input pole of the switching transistor Q1 is connected to the anode of the freewheeling diode D1 and one end of the capacitor C1, the cathode of the freewheeling diode D1 is connected to the positive pole of the power supply BAT1 and one end of the inductor L1, and the other end of the inductor L1 is connected to the other end of the capacitor C1.

[0074] Moving the switching transistor Q1 in the Buck circuit to the negative side compared to the traditional design of placing it on the positive side can simplify the design of the drive circuit. The specific analysis is as follows: when the switching transistor Q1 is placed on the negative side, the drive circuit of the switching transistor Q1, that is, the monostable flip-flop, can use a lower voltage to drive the switching transistor Q1, so the drive circuit design is usually simpler. The simplification of the drive circuit may reduce the need for expensive drive ICs or isolation components, reducing costs.

[0075] The switching transistor Q1 can be a MOSFET or a triode. When the switching transistor Q1 is a MOSFET, the input pole of the switching transistor Q1 is the drain of the MOSFET, the output pole of the switching transistor Q1 is the source of the MOSFET, and the gate of the switching transistor Q1 is the gate of the MOSFET. When the switching transistor Q1 is a triode, the input pole of the switching transistor Q1 is the collector of the triode, the output pole of the switching transistor Q1 is the emitter of the triode, and the gate of the switching transistor Q1 is the base of the triode.

[0076] In a possible implementation, any of the above-provided fan speed measurement devices further includes: a second resistor circuit, and the second resistor circuit is connected in parallel with the capacitor C1, as Figure 6 shown. The second resistor circuit is used as a dummy load to stabilize the voltage.

[0077] In a possible implementation, as Figure 7 shown, any of the above-provided fan speed measurement devices further includes: a differential operational amplifier 300; the first input terminal of the differential operational amplifier 300 is connected to the high-voltage terminal of the capacitor C1, the second input terminal of the differential operational amplifier 300 is connected to the low-voltage terminal of the capacitor C1, and the output terminal of the differential operational amplifier 300 is used to access the ADC port of the single-chip microcomputer.

[0078] Specifically, the differential operational amplifier is used to convert the differential input signal (i.e., the difference between the two input signals) into a single-ended output signal. The differential operational amplifier has the function of suppressing common-mode noise and interference in signal processing, and its output signal can be directly connected to the ADC port of the single-chip microcomputer for analog-to-digital conversion. As the voltage on the capacitor C1 gets higher and higher, the voltage at the output terminal VspeedOut of the differential operational amplifier gets higher and higher, and the single-chip microcomputer can calculate the fan speed based on the converted digital voltage.

[0079] Still referring toFigure 7 The differential operational amplifier 300 includes an operational amplifier U1, a third resistor circuit, a fourth resistor circuit, and a fifth resistor circuit;

[0080] The non-inverting input terminal of the operational amplifier U1 is connected to one end of the third resistor circuit, and the other end of the third resistor circuit serves as the first input terminal of the differential operational amplifier;

[0081] The inverting input terminal of the operational amplifier U1 is connected to one end of the fourth resistor circuit, and the other end of the fourth resistor circuit serves as the second input terminal of the differential operational amplifier;

[0082] The fifth resistor circuit is connected between the inverting input terminal and the output terminal of the operational amplifier U1;

[0083] The output terminal of the operational amplifier U1 serves as the output terminal VspeedOut of the differential operational amplifier 300.

[0084] Each resistor circuit in the embodiments of the present application can be a single resistor, or a series combination, a parallel combination, or a series-parallel combination (i.e., a connection method that includes both series and parallel connections) of multiple resistors.

[0085] In a possible implementation, referring to Figure 8 , the first resistor circuit 100 is resistor R4, the second resistor circuit is resistor RL, the third resistor circuit is resistor R1, the fourth resistor circuit is the parallel combination of resistor R3 and resistor R4, and the fifth resistor circuit is resistor R2.

[0086] In a possible implementation, the Hall sensor U3 is installed on the motor of the fan. The motor of the fan is the core component of the fan operation. It is responsible for converting electrical energy into mechanical energy, driving the fan blades to rotate, and thus generating air flow.

[0087] The various embodiments in this specification are described in a progressive manner. The key point of each embodiment is the difference from other embodiments. The same or similar parts among the embodiments can be referred to each other.

[0088] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the embodiments of the present application. Therefore, the embodiments of the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fan speed measuring device, characterized in that: include: Hall sensor, monostable trigger, first resistor circuit and Buck circuit; Wherein, the output positive electrode of the Hall sensor is connected to one end of the first resistance circuit, and the output negative electrode of the Hall sensor is grounded; The other end of the first resistance circuit is connected to a power supply and is also connected to a trigger input pin of the monostable trigger; The frequency of the pulse signal output by the Hall sensor is positively correlated with the rotation speed of the fan; The output end of the monostable trigger is connected to the gate of the switch tube in the Buck circuit; the input end of the Buck circuit is connected to a power supply; The monostable trigger is used to switch from low-level output to high-level output and maintain it when the trigger input pin receives a rising edge signal, and switch back to low-level output when the holding time of the high-level output reaches a preset time.

2. The fan speed measuring device according to claim 1, characterized in that: The monostable trigger is replaced by: when the trigger input pin receives a falling edge signal, it switches from a low level output to a high level output and maintains it, and when the holding time of the high level output reaches a preset time, it switches back to a low level output; The wind turbine speed measuring device further includes: an inverter connected between the second end of the first resistance circuit and the trigger input pin of the monostable trigger.

3. The wind turbine speed measuring device according to claim 1, characterized in that: The monostable trigger is replaced by: when the trigger input pin receives a rising edge signal, it switches from a high-level output to a low-level signal and maintains it, and when the holding time of the low-level signal reaches a preset time, it switches back to a high-level output; The wind turbine speed measuring device further includes: an inverter connected between the output end of the monostable trigger and the gate of the switch tube.

4. The wind turbine speed measuring device according to claim 1, characterized in that: The monostable trigger is replaced by: when the trigger input pin receives a falling edge signal, it switches from a high level output to a low level signal and maintains it, and when the holding time of the low level signal reaches a preset time, it switches back to a high level output; The wind turbine speed measuring device also includes: an inverter connected between the second end of the first resistance circuit and the trigger input pin of the monostable trigger, and an inverter connected between the output end of the monostable trigger and the gate of the switch tube.

5. The wind turbine speed measuring device according to any one of claims 1 to 4, characterized in that: The switch tube is installed on the negative electrode side of the Buck circuit.

6. The wind turbine speed measuring device according to any one of claims 1 to 4, characterized in that: The switch tube is a MOSFET or a triode.

7. The wind turbine speed measuring device according to any one of claims 1 to 4, characterized in that: The wind turbine speed measuring device further includes: a second resistance circuit, which is connected in parallel with the capacitor in the Buck circuit.

8. The wind turbine speed measuring device according to any one of claims 1 to 4, characterized in that: The wind turbine speed measuring device also includes: a differential operational amplifier; a first input end of the differential operational amplifier is connected to the high voltage end of the capacitor in the Buck circuit, a second input end of the differential operational amplifier is connected to the low voltage end of the capacitor, and an output end of the differential operational amplifier is used to access an analog-to-digital converter port of a single-chip microcomputer.

9. The wind turbine speed measuring device according to claim 8, characterized in that: The differential operational amplifier comprises an operational amplifier, a third resistance circuit, a fourth resistance circuit and a fifth resistance circuit; The in-phase input terminal of the operational amplifier is connected to one end of the third resistor circuit, and the other end of the third resistor circuit serves as the first input terminal of the differential operational amplifier; The inverting input terminal of the operational amplifier is connected to one end of the fourth resistor circuit, and the other end of the fourth resistor circuit serves as the second input terminal of the differential operational amplifier; The fifth resistor circuit is connected between the inverting input terminal and the output terminal of the operational amplifier; The output end of the operational amplifier serves as the output end of the differential operational amplifier.

10. The wind turbine speed measuring device according to any one of claims 1 to 4, characterized in that: The Hall sensor is mounted on the motor of the fan.

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