Generator rotating speed measuring system and method

Abstract

The invention discloses a generator rotating speed measuring system and method, and the system comprises a motor body which is provided with a rotating shaft. The light source module is used for generating a light source; the photoelectric module is used for irradiating the light source generated by the light source module to the end face of the rotating shaft; the counting module comprises an integrated phase-locked loop and a frequency divider, the integrated phase-locked loop and the frequency divider are matched to multiply the number of pulses output from the shaping circuit within one second by 60 and then send the multiplied number to a counter and a display circuit, and the phase discriminator PD1 adopts an exclusive-OR gate structure; transmission mechanical gear speed measurement is changed into infrared photoelectric speed measurement, a phase-locked loop tracking speed measurement method is adopted, and a phase-locked loop has the characteristic of no frequency difference after locking, so that rapid measurement when a prime mover is at a low speed is realized, the rotation speed of a prime mover rotor can be followed in real time, and the problem of long measurement period of a traditional speed measurement method is solved.

Description

Technical Field

[0001] The present invention relates to the field of generator speed measurement, and in particular to a generator speed measurement system and method. Background Art

[0002] In generator control, it is often necessary to measure the generator speed. The traditional method of measuring generator speed is to measure the speed of the gear disc. The gear disc speed is obtained by measuring the number of teeth passing through per unit time and combining the distance between teeth.

[0003] The existing generator speed measurement method has a long measurement cycle and counter overflow occurs at low speeds, which deteriorates the system control effect and causes a "climbing" phenomenon. At the same time, the stability when testing the generator speed is not high, which greatly affects the tester's evaluation of the generator performance. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is that the existing generator speed measurement method has a long measurement period.

[0005] The above technical problems are solved by the following technical solutions: The present invention proposes a generator speed measurement system, which includes a motor body, on which a rotating shaft is provided; a light source module, which is used to generate a light source; a photoelectric module, which is used to irradiate the light source generated by the light source module onto the end surface of the rotating shaft; and a counting module, which includes an integrated phase-locked loop and a frequency divider, and the integrated phase-locked loop and the frequency divider cooperate to multiply the number of pulses output from the shaping circuit in one second by 60, and then send them to the counter and display circuit.

[0006] In a preferred embodiment of the generator speed measurement system of the present invention: the photoelectric module includes a photoelectric unit, a discharge unit and a shaper.

[0007] In a preferred embodiment of the generator speed measurement system of the present invention: the integrated phase-locked loop includes a voltage-controlled oscillator VCO, a source follower A2, a voltage stabilizer, a linear amplification and shaping circuit A1, two phase detectors PD1 and PD2, and 16 pins.

[0008] In a preferred embodiment of the generator speed measurement system of the present invention: the phase detector PD1 adopts an exclusive OR gate structure.

[0009] In a preferred embodiment of the generator speed measurement system of the present invention: the phase detector PD2 can input an asymmetric waveform, and the phase detector PD2 is provided with a capture frequency range; the two phase detectors are output by pins 2 and 13 respectively, and pin 1 is the other output end of the phase detector PD2, which outputs a locking signal that can be used as an indication of the phase-locked loop locking state.

[0010] In a preferred embodiment of the generator speed measurement system of the present invention, the input signal Ui at the pin 14 is firstly amplified and shaped by the circuit A1 so that its level and waveform meet the requirements of the phase detector.

[0011] In a preferred embodiment of the generator speed measurement system of the present invention, the loop filter uses an external resistor-capacitor network R3, R4, and R2, and the control voltage output by the network is connected to the input pin 9 of the voltage-controlled oscillator VCO.

[0012] In a preferred embodiment of the generator speed measurement system of the present invention: the voltage-controlled oscillator VCO adopts a cross-charge and discharge type voltage-controlled oscillator, and the charging current of the timing capacitor C1 by the voltage-controlled oscillator VCO is proportional to the control voltage input from pin 9; the output waveform of the voltage-controlled oscillator VCO is a symmetrical square wave.

[0013] In a preferred embodiment of the generator speed measurement system of the present invention: when the phase-locked loop is used for demodulating the frequency modulated wave, the control voltage output by the loop filter is transmitted through the source follower A2 to pin 10 to obtain the FM demodulation signal, and a load resistor R5 is connected between pin 10 and the ground.

[0014] In order to solve the above technical problems, the present invention also provides a generator speed measurement method: applied to a generator speed measurement system, further comprising:

[0015] First, a reflective marker is pasted on the shaft of the motor to be tested, and the light source module shines a beam of light onto the end face of the shaft to be tested through the optical system; every time the motor rotates one circle, the intensity of the reflected light projected onto the photoelectric element changes, so that the photoelectric element generates a pulse signal every time it is exposed to light; next, the pulse signal is shaped and amplified, and sent to the counter, which counts the input pulse signal to measure the number of pulses per unit time, which can be converted into the motor speed; then the counter counts incrementally under the triggering of the pulse signal output by the multiplier, accumulates the number of pulses generated per unit time, and resets the counter once per minute; finally, before each periodic reset, the value recorded by the counter is transmitted to the display module for storage. The number stored in the display module remains unchanged for the next 1 minute and is directly displayed, so that the number of revolutions per minute of the motor, that is, the speed of the motor to be tested, can be recorded.

[0016] The beneficial effects of the present invention are as follows: by changing the transmission mechanical gear speed measurement to infrared photoelectric speed measurement and adopting a phase-locked loop tracking speed measurement method, since the phase-locked loop has the characteristic of no frequency difference after locking, rapid measurement of the prime mover at low speed is achieved, and the speed of the prime mover rotor can be followed in real time, thereby solving the problem of long measurement cycle of traditional speed measurement methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments of the present invention. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Among them:

[0018] Figure 1 Shows the system block diagram of the generator speed measurement system;

[0019] Figure 2 The circuit diagram of the 60-frequency multiplier of the generator speed measurement system is shown;

[0020] Figure 3 The schematic diagram of the integrated phase-locked loop of the generator speed measurement system is shown;

[0021] Figure 4 The flow chart of the generator speed measurement method is shown.

[0022] In the figure: 100, motor body; 200, light source module; 300, photoelectric module; 301, photoelectric unit; 302, discharge; 303, shaping; 400, counting module; 500, display module. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to specific embodiments and the accompanying drawings.

[0024] The terms used in the present invention are those commonly used in the art in view of the functions of the present invention, but these terms may vary according to the intentions of those skilled in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the present invention. Therefore, the terms used in the specification should not be understood as simple names, but rather as the meanings of the terms and the overall description of the present invention.

[0025] Reference Figure 1 This embodiment provides a generator speed measurement system, including: Figure 1-3As shown, the present invention provides a synchronous AC generator speed measurement system, including a motor body 100, on which a rotating shaft is provided; a light source module 200, for generating a light source; a photoelectric module 300, for irradiating the light generated by the light source module 200 onto the end surface of the rotating shaft; and a counting module 400, wherein the counting module 400 includes an integrated phase-locked loop and a frequency divider, and the integrated phase-locked loop and the frequency divider cooperate to multiply the number of pulses output from the shaping circuit 303 in one second by 60, and then send the pulses to the counter and display circuit.

[0026] The photoelectric module 300 includes a photoelectric unit 301, a discharge 302, and a shaping circuit 303. The photoelectric unit 301 adopts one of a photodiode, a phototransistor, a photocell and an incandescent bulb. The photoelectric module 300 is used to irradiate the light beam generated by the light source module 200 to the end face of the motor shaft. The photoelectric element captures the change in the intensity of the reflected light caused by the reflective mark when the shaft rotates and converts it into a pulse signal. At the same time, the signal is discharged 302 to eliminate interference. The irregular waveform is then adjusted to a regular square wave pulse through the shaping circuit 303 to ensure that its level and waveform meet the processing requirements of the phase-locked loop and divider in the subsequent counting module 400, ultimately achieving high-precision acquisition and conversion of the speed signal.

[0027] The counter includes an integrated phase-locked loop and a frequency divider to form a 60-fold frequency multiplier. The integrated phase-locked loop includes a voltage-controlled oscillator VCO, a source follower A2, a voltage stabilizer, a linear amplification and shaping circuit 303 A1, two phase detectors PD1 and PD2, and 16 pins. Preferably, the phase detector PD1 adopts an exclusive OR gate structure. When the level states of the two input signals Ui and Uo are different, the output signal UΨ is a high level. Conversely, when the level states of Ui and Uo are the same, the output UΨ is a low level. When the phase difference Δφ of Ui and Uo changes between 0 and 80°, the pulse width of UΨ will also change accordingly, that is, the duty cycle is also changing. For the phase detector PD1, the duty cycles of Ui and Uo are both 50%, the phase detector PD2 is a digital storage phase detector triggered by the rising edge of the signal. The phase detector PD2 has low requirements for the duty cycle of the input signal and allows the input of asymmetric waveforms. The phase detector PD2 has a wide capture frequency range and will not lock the harmonics of the input signal. The two phase detectors are output by pins 2 and 13 respectively. Pin 1 is the other output terminal of the phase detector PD2, which outputs a lock signal that can be used as an indication of the lock state of the phase-locked loop. When lock is achieved, a 0° phase shift is maintained between the two input signals of the phase detector PD2. The input signal Ui at pin 14 needs to be amplified and shaped by circuit A1 303 so that its level and waveform meet the requirements of the phase detector.

[0028] The loop filter uses an external resistor-capacitor network R3, R4, and R2, and its output control voltage is connected to the input pin 9 of the voltage-controlled oscillator VCO. The voltage-controlled oscillator VCO uses a cross-charge and discharge 302 type voltage-controlled oscillator, so an external capacitor C1 and resistor R1 are connected between pins 6 and 7 as charging and discharging 302 elements. When the phase-locked loop has requirements for the frequency width of the input signal to be tracked, an external resistor R2 is also required. Since the voltage-controlled oscillator VCO is a current-controlled oscillator, the charging current of the timing capacitor C1 is proportional to the control voltage input from pin 9, so that the oscillation frequency of the voltage-controlled oscillator VCO is also proportional to the control voltage. When the control voltage of the voltage-controlled oscillator (VCO) is 0, its output frequency is the lowest. When the input control voltage is equal to the power supply voltage (VDD), the output frequency increases linearly to the maximum output frequency. The oscillation frequency range of the voltage-controlled oscillator (VCO) is determined by R1, R2, and C1. Since the charging and discharging 302 of the voltage-controlled oscillator (VCO) are both completed by the same capacitor (C1), the output waveform of the voltage-controlled oscillator (VCO) is a symmetrical square wave. When the phase-locked loop is used to demodulate FM waves, the control voltage output by the loop filter is transmitted to pin 10 via source follower A2 to obtain the FM demodulation signal. A load resistor R5 is connected between pin 10 and ground.

[0029] In this embodiment, input signal Ui is input from pin 14, amplified and shaped 303 by amplifier A1, and then applied to the input terminals of phase detectors PD1 and PD2. When switch K is set to pin 2, phase detector PD1 compares the phase of comparison signal Uo input from pin 3 with input signal Ui. The error voltage UΨ output by phase detector PD1 reflects the phase difference between the two. UΨ is filtered by resistors R3, R4, and C2 to generate a control voltage Ud, which is applied to the input terminal pin 9 of the voltage-controlled oscillator (VCO). This adjusts the oscillation frequency f2 of the VCO so that f2 rapidly approaches the input signal frequency f1. The output of the VCO then passes through a frequency divider and enters phase detector PD1 for further phase comparison with Ui. Ultimately, f2 is set to equal f1, and the phase difference between the two is constant, achieving phase lock. When switch K is set to pin 13, phase detector PD2 operates in the same process as phase detector PD1.

[0030] As an optional embodiment, Figure 4 As shown, the present invention provides a method for measuring the speed of a synchronous AC generator, which comprises the following steps:

[0031] Step 1: A reflective marker is attached to the motor shaft to be tested, and the light source module 200 irradiates a beam of light onto the end face of the shaft to be tested through the optical system;

[0032] Step 2: Every time the motor rotates one circle, the intensity of the reflected light projected onto the photoelectric element changes, so the photoelectric element generates a pulse signal every time it receives light;

[0033] Step 3: The pulse signal is shaped 303, amplified, and sent to a counter. The counter counts the input pulse signal, thereby measuring the number of pulses per unit time, which can be converted into motor speed.

[0034] Step 4: The counter counts up when triggered by the pulse signal output by the frequency multiplier, accumulates the number of pulses generated per unit time, and resets the counter once per minute;

[0035] Step 5: Before each periodic reset, the value recorded by the counter is transmitted to the display module 500 for storage. The number stored in the display module 500 remains unchanged for the next 1 minute and is directly displayed. In this way, the number of revolutions per minute of the motor, that is, the speed of the motor being measured, can be recorded.

[0036] In this embodiment, before counting the pulse signal, a 60-times frequency multiplier must be added to the circuit. The output signal frequency of the 60-times frequency multiplier is fo, which is 60 times the input signal frequency fi. Its function is to multiply the number of pulses output from the shaping circuit 303 in one second by 60, and then send it to the counter and display circuit. The displayed value is the motor speed r / min at that moment, thereby realizing fast and real-time measurement of the motor speed.

[0037] Finally, it should be pointed out that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways without departing from the scope of the present invention.

Claims

1. A generator speed measurement system, characterized by: include, A motor body (100), wherein a rotating shaft is provided on the motor body (100); A light source module (200), the light source module (200) is used to generate a light source; a photoelectric module (300), the photoelectric module (300) being used to irradiate the light source generated by the light source module (200) onto the end surface of the rotating shaft; and A counting module (400) includes an integrated phase-locked loop and a frequency divider, wherein the integrated phase-locked loop and the frequency divider cooperate to multiply the number of pulses output from the shaping circuit (303) within one second by 60, and then send the pulses to the counter and display circuit.

2. The generator speed measurement system according to claim 1, characterized in that: The photovoltaic module (300) includes a photovoltaic unit (301), a discharge unit (302) and a shaper (303); The photoelectric module (300) is used to irradiate the light beam generated by the light source module (200) onto the end surface of the motor shaft; Discharging (302) is used to eliminate signal interference; The shaping circuit (303) is used to adjust the irregular waveform into a regular square wave pulse.

3. The generator speed measurement system according to claim 2, characterized in that: The integrated phase-locked loop comprises a voltage-controlled oscillator VCO, a source follower A2, a voltage stabilizer, a linear amplification and shaping (303) circuit A1, two phase detectors PD1 and PD2, and 16 pins.

4. The generator speed measurement system according to claim 3, characterized in that: The phase detector PD1 adopts an exclusive OR gate structure.

5. The generator speed measurement system according to claim 4, characterized in that: The phase detector PD2 can input an asymmetric waveform, and the phase detector PD2 is set with a capture frequency range; The two phase detectors are output by pins 2 and 13 respectively. Pin 1 is the other output end of phase detector PD2, which outputs a lock signal that can be used as an indication of the phase-locked loop lock state.

6. The generator speed measurement system according to claim 5, characterized in that: The input signal Ui at pin 14 is first amplified and shaped by circuit A1 (303) so that its level and waveform meet the requirements of the phase detector.

7. The generator speed measurement system according to claim 6, characterized in that: The loop filter uses an external resistor-capacitor network R3, R4, and R2, and the control voltage output by the network is connected to the input pin 9 of the voltage-controlled oscillator VCO.

8. The generator speed measurement system according to claim 7, characterized in that: The voltage controlled oscillator VCO adopts a cross-charge and discharge (302) type voltage controlled oscillator, and the charging current of the timing capacitor C1 by the voltage controlled oscillator VCO is proportional to the control voltage input from the pin 9; The output waveform of the voltage controlled oscillator VCO is a symmetrical square wave.

9. The generator speed measurement system according to claim 8, characterized in that: When the phase-locked loop is used for demodulating FM waves, the control voltage output by the loop filter is transmitted to pin 10 via source follower A2 to obtain an FM demodulation signal. A load resistor R5 is connected between pin 10 and the ground.

10. A method for measuring generator speed, characterized in that: The generator speed measurement system according to any one of claims 1 to 9 further includes: First, a reflective mark is attached to the motor shaft to be tested, and a light source module (200) irradiates a beam of light onto the end face of the shaft to be tested through an optical system; Every time the motor rotates one circle, the intensity of the reflected light projected onto the photoelectric element changes, so the photoelectric element generates a pulse signal every time it receives light. Next, the pulse signal is shaped (303), amplified, and sent to a counter. The counter counts the input pulse signal, thereby measuring the number of pulses per unit time, which can be converted into the motor speed. Then the counter counts up under the trigger of the pulse signal output by the frequency multiplier, accumulates the number of pulses generated per unit time, and resets the counter once per minute; Finally, at the moment before each periodic reset, the value recorded by the counter is transmitted to the display module (500) for storage. The number stored in the display module (500) remains unchanged for the next 1 minute and is directly displayed, so that the number of revolutions per minute of the motor, that is, the speed of the motor being measured, can be recorded.

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