Motor speed measurement device and method based on electromagnetic induction

Abstract

The invention provides a motor speed measuring device and method based on electromagnetic induction, and belongs to the technical field of motor rotating speed measurement. The motor speed measuring device comprises a signal acquisition device, a signal processing module and a main control unit; the signal acquisition device is used for acquiring a motor magnetic flux leakage signal and inducing to generate an input voltage signal; the stator current frequency signal processing unit comprises a filter circuit, a signal amplification circuit and a shaping frequency dividing circuit; the preprocessed input voltage signal passes through the filter circuit and the signal amplification circuit to obtain a sine wave signal; the sinusoidal signal is processed by the shaping frequency dividing circuit to obtain a square signal which is fed back to the main control unit; the rotor current frequency signal processing unit converts a rotor current frequency signal into a square wave signal and feeds back the square wave signal to the main control unit; and the main control unit obtains the rotating speeds of different motors through frequency division filtering, maximum and minimum value filtering and multi-channel signal comparison processing and calculation. The rotating speed of the synchronous motor and the rotating speed of the asynchronous motor can be measured, and the universality of the device is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of motor speed measurement, and particularly relates to a motor speed measurement device and method based on electromagnetic induction. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] The accurate measurement of motor speed is of great significance in production applications. Current motor speed measurement methods mainly include acoustic speed measurement, Hall sensor / optical encoder method, current analysis method, vibration spectrum analysis method, etc. For submersible pumps, submersible oil pumps and other types of completely sealed motors, due to their special structure and working environment, it is impossible to install reflective stickers, magnetic steel and optical probes, and only non-contact speed measurement methods with relatively low environmental requirements can be used.

[0004] The existing completely sealed motor speed measurement methods are: ① using a galvanometer to measure the frequency with a stopwatch, but the operation is troublesome and the accuracy is poor; ② analyzing the harmonic frequency of the motor stator current to extract the slip rate or synchronous speed information, but the precision is greatly affected by load fluctuations and power grid interference. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the present application provides a motor speed measurement device and method based on electromagnetic induction, which solves the difficulty of measuring the speed of submersible pumps, submersible oil pumps and other types of completely sealed motors, and provides a speed measurement method and device that meets the requirements of motor structure and working environment and has high measurement accuracy. The stator current and rotor current frequencies are detected in real time, the influence of load fluctuations and power grid interference on motor speed detection is reduced, and the stator current frequency is detected in real time, so there is no need to read the output frequency value of the frequency converter, thereby improving the independence and universality of the device.

[0006] To achieve the above object, one or more embodiments of the present application provide the following technical solutions: In a first aspect, a motor speed measurement device based on electromagnetic induction is disclosed, comprising a signal acquisition device, a signal processing module and a main control unit. The signal acquisition device is used to acquire motor leakage magnetic signals and generate input voltage signals, and comprises a core, a winding and a shielded shell. The winding is wound on the core, and the winding and the core are sealed in the shielded shell. The signal processing module comprises a stator current frequency signal processing unit and a rotor current frequency signal processing unit; the stator current frequency signal processing unit comprises a filter circuit, a signal amplification circuit and a shaping frequency division circuit, and a preprocessed input voltage signal is subjected to the filter circuit and the signal amplification circuit to obtain a sine wave signal; the sine wave signal is subjected to the shaping frequency division circuit to obtain a square wave signal which is fed back to the main control unit; the rotor current frequency signal processing unit converts a rotor current frequency signal into a square wave signal which is fed back to the main control unit. The main control unit obtains a frequency division signal by frequency division filtering of the square wave signal, obtains a single pulse signal period by mean value processing of the frequency division signal, performs maximum and minimum value filtering on array values in a sampling period and takes an average value, obtains a period value of the current frequency signal in the sampling period according to the average value, and calculates the rotating speed of the motor according to the period value.

[0007] In a second aspect, a motor speed measurement method based on electromagnetic induction is disclosed, comprising: A motor leakage magnetic signal is collected and an input voltage signal is induced and generated, the collected voltage signal is subjected to a signal processing module to obtain a stator current frequency signal and a rotor current frequency signal for subsequent processing, the stator current frequency signal is processed by a stator current frequency signal processing unit to obtain a square wave signal, and the rotor current frequency signal is converted into a square wave signal by a rotor current frequency signal processing unit. A frequency division signal is obtained by frequency division filtering of the square wave signal, a single pulse signal period is obtained by mean value processing of the frequency division signal, maximum and minimum value filtering is performed on array values in a sampling period and an average value is taken, a period value of the current frequency signal in the sampling period is obtained according to the average value, and the rotating speed of the motor is calculated according to the period value.

[0008] Compared with the prior art, the present application has the following beneficial effects: The signal collection device is attached to the shaft end of the motor, and the motor rotating speed signal is collected in real time, so that the operation is simple and manual operation is not required. The stator current frequency signal and the rotor current frequency signal are obtained by processing the collected signals by the stator current frequency signal processing unit and the rotor current frequency signal processing unit, so that the device can measure the rotating speed of a synchronous motor and the rotating speed of an asynchronous motor, and the universality of the device is realized. The stator current frequency signal is processed by two shaping frequency division circuits, the current frequency is determined when the frequency values measured by the two channels are equal, the measurement error is reduced, and the signal anti-interference capability is improved. The signal processing of the application improves the signal processing precision by combining hardware filtering and software filtering, specifically, the signal is fed back to the main control unit after being processed by the hardware filtering and frequency division circuit, and then is processed by signal frequency division, maximum and minimum value filtering and other processing methods, thereby reducing the influence of load fluctuation and power grid interference on motor speed detection and improving the signal processing precision.

[0009] Advantages of the additional aspects of the application will be partly given in the following description, partly will become apparent from the following description, or will be learned by the practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0010] The accompanying drawings, which form a part of the specification, are included to provide a further understanding of the application and are incorporated herein by reference. The illustrations are shown schematically and are not intended to limit the application in any way.

[0011] Figure 1 The signal acquisition device described in embodiment one of the application is shown in the schematic diagram.

[0012] Figure 2 The stator current frequency signal filtering and amplifying circuit described in embodiment one of the application is shown in the schematic diagram.

[0013] Figure 3 The stator current frequency signal shaping and frequency division circuit described in embodiment one of the application is shown in the schematic diagram.

[0014] Figure 4 The rotor current frequency signal filtering circuit described in embodiment one of the application is shown in the schematic diagram.

[0015] Figure 5 The rotor current frequency signal amplifying circuit described in embodiment one of the application is shown in the schematic diagram. DETAILED DESCRIPTION

[0016] It should be noted that the following detailed description is merely exemplary and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs.

[0017] It should be noted that the terms used herein are merely intended to describe specific embodiments and are not intended to limit the exemplary embodiments according to the application.

[0018] The embodiments in the application and the features in the embodiments can be combined with each other without conflict.

[0019] Embodiment one In one or more embodiments, a motor speed measurement device based on electromagnetic induction is disclosed, comprising a signal acquisition device, a signal processing module and a main control unit. The signal acquisition device is used for acquiring the magnetic flux leakage signal of the motor and generating an input voltage signal, as shown in the figure, which comprises an induction coil composed of a core 2, a winding 3 and a shielded shell 1, wherein the core 2 is made of ultra-fine crystal material, the winding 3 is wound on the core 2 by 30000 turns of enameled wire, and the core 2 and the winding 3 are sealed in the shielded shell 1 by epoxy resin; the signal acquisition device is attached to the shaft end of the motor to acquire the magnetic flux leakage at the shaft end of the motor and generate an induction signal. Figure 1

[0020] The signal processing module comprises a power distribution unit, a stator current frequency signal processing unit and a rotor current frequency signal processing unit.

[0021] The power distribution unit comprises a power conversion module and a voltage dividing circuit, which is used for pre-processing the conversion of the power supply voltage into the voltage required by different elements, adopts 24V to 24V, 24V to 5V, 5V to 3.3V power conversion module, and provides power supply voltage and bias voltage for main control chip, amplifier, flip-flop and other elements. And the voltage signal fed back by the signal acquisition device is lifted to 12v through the voltage dividing circuit, so that the fluctuation range of the induction signal voltage is within the voltage range of 0-24v, and the input signal is generated; The stator current frequency signal processing unit comprises a filter circuit, a signal amplification circuit and a shaping frequency division circuit. The input signal is filtered by the filter circuit and the signal amplification circuit to obtain a sine wave signal, and the signal amplification circuit comprises an amplification filter circuit and an amplification circuit, as shown in the figure, the input signal is filtered by the filter circuit composed of the first capacitor C31 and the first inductor L1 to filter out the frequency signal above 339HZ. Then, the amplification filter circuit composed of the first operational amplifier TLC2272, the first resistor R93, the second resistor R94, the second capacitor C93, the third capacitor C94, etc. and the amplification circuit composed of the second operational amplifier LM386, the fourth capacitor C33, the fifth capacitor C34, etc. are obtained. Sine wave signal. Figure 2

[0022] ​​Specifically, one end of the first capacitor C31 is grounded, and the other end is connected to one end of the first inductor L1 and the input signal respectively, and the other end of the first inductor L1 is connected to the non-inverting input terminal of the first operational amplifier TLC2272; the first resistor R93 and the second capacitor C93 are connected in parallel, one end of which is grounded, and the other end is connected to the inverting input terminal of the first operational amplifier TLC2272 and one end of the second resistor R94 and the third capacitor C94 connected in parallel respectively, and the other end of the second resistor R94 and the third capacitor C94 connected in parallel is connected to the output terminal of the first operational amplifier TLC2272. The output terminal of the first operational amplifier TLC2272 is connected to the third pin of the second operational amplifier LM386, one end of the fourth capacitor C33 is connected to the first pin GAIN of the second operational amplifier, and the other end is connected to the eighth pin GAIN, and the seventh pin of the second operational amplifier is connected to the fifth capacitor C34.

[0023] The stator current frequency signal is shaped and processed by two shaping frequency division circuits, and the signal output at the vout end of the second operational amplifier LM386 amplifier is filtered by the sixth capacitor C35 and the seventh capacitor CT15, then connected to the optocoupler, and after isolation by the optocoupler, a signal TB-P1 is generated, as shown in Figure 3 The TB-P1 is connected to two shaping frequency division circuits respectively to shape and process the stator current frequency signal, the first circuit is that the TB-P1 is connected to the pin 1 of the inverter, and after inverting shaping processing, it is connected to the pin 2 and the third resistor R150 to the pin 3 of the flip-flop, and after 4 frequency division, it is output through the pin 9 of the flip-flop; the second circuit is that the TB-P1 is connected to the pin 1 of the inverter, and after inverting shaping processing, it is connected to the pin 13 of the inverter, and after inverting processing again, it is output from the pin 12 of the inverter. After processing by the two circuits, a square wave signal is obtained, which is fed back to the main control unit for subsequent processing.

[0024] The rotor current frequency signal processing unit is composed of RC low-pass filter circuit, active low-pass filter circuit and signal amplification circuit. As shown in Figure 4 The input voltage signal collected by the signal collection device is a mixed signal, which includes rotor current frequency signal, stator current frequency signal and interference signal; the input signal passes through the RC low-pass filter circuit composed of the fourth resistor R1, the eighth capacitor CT1, the fifth resistor R2, the ninth capacitor CT17, the sixth resistor R5 and the tenth capacitor CT2, and two first-order active low-pass filter circuits composed of the seventh resistor R4, the eighth resistor R3, the eleventh capacitor C1, the third operational amplifier LM324 and the ninth resistor R7, the tenth resistor R8, the twelfth capacitor C2 and the fourth operational amplifier LM324, to filter out the stator frequency signal and high-frequency noise signal, and after amplification processing by the amplification circuit as shown in Figure 5 A sinusoidal wave signal of the rotor current frequency is obtained. After isolation by the optocoupler and inverter shaping processing, the rotor current frequency signal is converted into a square wave signal and fed back to the main control unit.

[0025] Specifically, the first end of the fourth resistor R1 is connected to the input signal, and the second end is connected to the first end of the eighth capacitor CT1 and the first end of the fifth resistor R2. The second end of the eighth capacitor CT1 is connected to the first end of the ninth capacitor CT17. The second end of the ninth capacitor CT17 is connected to the second end of the fifth resistor R2. The first end of the ninth capacitor CT17 is connected to one end of the seventh resistor R4, the first end of the tenth capacitor CT2, and the first end of the ninth resistor R7. The other end of the seventh resistor R4 is connected to the non-inverting input of the third operational amplifier. The second end of the fifth resistor R2 is connected to the inverting input of the third operational amplifier. The eighth resistor R3 and the eleventh capacitor C1 are connected in parallel, and their two ends are connected to the inverting input and output of the third operational amplifier, respectively. The output of the third operational amplifier is connected to the inverting input of the fourth operational amplifier through the sixth resistor R5. The second end of the ninth resistor R7 is connected to the non-inverting input of the fourth operational amplifier. The tenth resistor R8 and the twelfth capacitor C2 are connected in parallel, and their two ends are connected to the inverting input and output of the fourth operational amplifier, respectively. The output signal of the fourth operational amplifier is input to the amplification circuit. The amplifier circuit is as follows: the input signal is input to the inverting input of the fifth operational amplifier through the eleventh resistor R15. The non-inverting input of the fifth operational amplifier is grounded through the twelfth resistor R16. One end of the thirteenth resistor R17 is connected to the inverting input of the fifth operational amplifier through the fourteenth resistor R18, and the other end is connected to the output of the fifth operational amplifier. The output of the fifth operational amplifier produces a sine wave signal. This circuit filters out noise signals from the input signal and amplifies the input signal, providing a stable sine wave signal for subsequent shaping.

[0026] Even after hardware processing, the signals fed back to the main control unit still contain interference and anomalies, affecting the accuracy of motor speed processing. The main control unit processes and calculates the speeds of different motors through frequency division filtering, maximum and minimum value filtering, and multi-channel signal comparison. The specific processing procedure is as follows: (1) Acquisition of synchronous motor speed There is no speed difference between the stator and rotor of a synchronous motor. The speed of the synchronous motor can be calculated by processing the stator current frequency signal. After the stator current frequency signal is fed back to the main control unit, it is first automatically divided into frequencies, with the division coefficient N (rounded to the nearest integer). ,in The stator current frequency calculated for the previous sampling period , The frequency is set to 10Hz. After frequency division, the output frequency signal is averaged to obtain the period of a single pulse signal. , , n is the number of pulses in the frequency division output period, after frequency division, the aliasing effect of data is reduced, and the sampling precision is improved. The obtained single pulse period value is stored in a one-dimensional array, and the array size is 40. The sampling period is set to 1s, and the maximum and minimum value filtering processing is performed on the array values obtained in the sampling period. After multiple filtering processing, the average value of the array is obtained. When the average value of the array and each value in the array after filtering processing are equal, the average value of the array is taken as the period value of the stator current frequency signal in the sampling period, and the stator current frequency value is calculated.

[0027] It should be understood that the single pulse period value is the time value of a pulse, and the values of different pulse periods are not necessarily equal; the array values obtained in the sampling period refer to 40 single pulse period values sampled in the sampling period of 1s to form an array; The average value of the array and each value in the array after filtering processing are equal, specifically, wherein the average value of the array is the average value obtained after multiple filtering processing, each value in the array after filtering processing is the remaining value in the array after filtering, and the average value is the value obtained by adding and averaging each value in the array after filtering. When the stator current frequency is stable, the values in the sampling period are equal. The purpose of this processing is to obtain the frequency of the stator current in the steady state According to the designed hardware circuit, the stator current frequency signal is fed back to the control unit through two channels, and the feedback signal is processed to obtain the stator current frequency value 、 Only when the stator current frequency values obtained by the two channels are equal, that is, = , the is taken as the stator current frequency in this sampling period. If ≠ , the stator current frequency remains unchanged at the frequency value of the last sampling period. According to the formula , the synchronous motor speed can be further calculated.

[0028] (2) Asynchronous motor speed acquisition The asynchronous motor speed acquisition needs to obtain the stator current frequency value and the rotor current frequency value, and the processing method of the stator current frequency is the same as that of the synchronous motor. After processing, the stator current frequency value The asynchronous motor rotor current frequency signal is fed back to the main control unit, first the signal is automatically frequency-divided, and the frequency signal output after frequency division is processed by averaging to obtain a single pulse signal period value and stored in an array, then the array in the 1s sampling period is processed by maximum and minimum value filtering, the average value of the array is obtained after multiple filtering, and the average value of the array is taken as the period value of the rotor current frequency signal in the sampling period, and the rotor current frequency value is calculated According to the formula The speed of the asynchronous motor can be further calculated.

[0029] Preferably, a code switch is installed in the speed measurement device hardware circuit, which is connected with the main control unit through the PCB copper-clad line, and different codes are set according to the pole pairs of the motor to be measured The control unit calculates the speed of the motor with different pole pairs according to the feedback of different code combinations. The universality of the device is improved, and the speed measurement demand of motors with different pole pairs is met.

[0030] Example two In one or more embodiments, a motor speed measurement method based on electromagnetic induction is disclosed, comprising: Step S1, collecting motor leakage magnetic signal and generating input voltage signal by induction.

[0031] Step S2, lifting the midpoint voltage of the collected induction signal to 12v through a voltage dividing circuit, so that the fluctuation range of the induction signal voltage is within 0-24v voltage range, obtaining the stator current frequency signal and the rotor current frequency signal for subsequent processing; the stator current frequency signal is processed by a stator current frequency signal processing unit to obtain a square wave signal, which is fed back to the main control unit; the rotor current frequency signal is converted into a square wave signal by a rotor current frequency signal processing unit and fed back to the main control unit; Specifically, the working principle of the stator current frequency signal processing unit is: The stator current frequency signal processing unit first filters out high-frequency signals above 339HZ, and then filters out low-frequency signals including the rotor current frequency signal, the processed signals are amplified and subjected to two different shaping processes, one is frequency division processing to better filter out noise signals, and the other is not frequency division. The two signals are fed back to the main control unit for processing, and when the collected stator current frequency is stable and free of interference, the stator current frequency values obtained by processing the two signals are equal. The use of two different shaping methods improves the detection accuracy of the stator current frequency signal and reduces load fluctuations and power grid interference.

[0032] Specifically, the working principle of the rotor current frequency signal processing unit is: The rotor current frequency signal processing unit extracts the low frequency rotor current frequency from the induction signal outputted by the acquisition device. Since the stator current frequency signal is higher than the rotor current frequency signal, the stator frequency signal and the high frequency noise signal are filtered out by a low pass filter circuit first, and then a smooth square wave signal is obtained after isolation and shaping.

[0033] In step S3, the square wave signal is divided by frequency filtering to obtain a divided frequency signal, the divided frequency signal is processed by mean value to obtain a single pulse signal period, the maximum and minimum values of the array values in the sampling period are filtered and averaged, the period value of the current frequency signal in the sampling period is obtained according to the average value, and the speed of the motor is calculated according to the period value.

[0034] The specific method is: (1) Synchronous motor speed acquisition There is no speed difference between the stator and the rotor of the synchronous motor, and the speed of the synchronous motor can be calculated by processing the stator current frequency signal. After the stator current frequency signal is fed back to the main control unit, the signal is first automatically divided by frequency, the division coefficient N (integer by rounding method), , wherein is the stator current frequency calculated in the previous sampling period , is 10 HZ. After frequency division, the output frequency signal is processed by mean value to obtain a single pulse signal period , , n is the number of pulses in the frequency division output period, and the aliasing effect of the data is reduced after frequency division, improving the sampling accuracy. The single pulse period value obtained by processing is stored in a one-dimensional array, and the array size is 40. The sampling period is set to 1s, and the maximum and minimum values of the array values obtained in the sampling period are filtered. After multiple filtering processing, the average value of the array is obtained. When the array average value and each value in the filtered array are equal, the array average value is taken as the period value of the stator current frequency signal in the sampling period, and the stator current frequency value is calculated.

[0035] According to the designed hardware circuit, the stator current frequency signal is fed back to the control unit through two channels, and the stator current frequency value , is obtained after the feedback signal is processed. Only when the stator current frequency values obtained by the two channels are equal, that is, = , the is taken as the stator current frequency in this sampling period. If ≠ , the stator current frequency remains the same as the frequency value in the previous sampling period. According to the formula , the speed of the synchronous motor can be further calculated.

[0036] (2) Asynchronous motor speed acquisition The asynchronous motor speed acquisition needs to obtain the stator current frequency value and the rotor current frequency value. The stator current frequency processing method is the same as that of the synchronous motor. After processing, the stator current frequency value is finally obtained . After the asynchronous motor rotor current frequency signal is fed back to the control unit, the signal is first automatically frequency-divided, and the frequency signal output after frequency division is processed by mean value. The single pulse signal period value is obtained and stored in an array. The maximum and minimum value filtering processing is performed on the array in 1s sampling period. After multiple filtering processing, the average value of the array is obtained. The average value of the array is taken as the period value of the rotor current frequency signal in the sampling period, and the rotor current frequency value is calculated . According to the formula , the speed of the asynchronous motor can be further calculated.

[0037] The present application is described with reference to flowcharts and / or block diagrams of the method, device (system) and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device that realizes the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams. Figure 1 The computer program instructions can also be stored in a computer readable memory capable of guiding the computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer readable memory produce a manufactured product including instruction devices, which realize the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams. Figure 1 The computer program instructions can also be loaded into the computer or other programmable data processing device to execute a series of operation steps on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams. The computer program instructions can also be loaded into the computer or other programmable data processing device to execute a series of operation steps on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams.

[0038] The computer program instructions can also be loaded into the computer or other programmable data processing device to execute a series of operation steps on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams. Figure 1 The computer program instructions can also be loaded into the computer or other programmable data processing device to execute a series of operation steps on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams. Figure 1 The computer program instructions can also be loaded into the computer or other programmable data processing device to execute a series of operation steps on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams. The computer program instructions can also be loaded into the computer or other programmable data processing device to execute a series of operation steps on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams.

[0039] The computer program instructions can also be loaded into the computer or other programmable data processing device to execute a series of operation steps on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams. Figure 1 The computer program instructions can also be loaded into the computer or other programmable data processing device to execute a series of operation steps on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams. Figure 1 The computer program instructions can also be loaded into the computer or other programmable data processing device to execute a series of operation steps on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams. The computer program instructions can also be loaded into the computer or other programmable data processing device to execute a series of operation steps on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one or more flows or one or more blocks in the flowcharts and / or block diagrams.

[0040] The description of each of the above-mentioned embodiments has a focus on that embodiment. Parts that have not been described in detail for a certain embodiment can be gathered from the description of the other embodiments.

[0041] The above descriptions are merely some embodiments of the present application, not intended to limit the present application. According to the application, various modifications and variations can be made thereto by those skilled in the art without departing from the spirit and principles of the application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall fall within the scope of the present application.

Claims

1. An electromagnetic induction based motor speed sensing device, characterized in that, The motor current frequency signal processing unit comprises an RC low-pass filter circuit, an active low-pass filter circuit and a signal amplification circuit. The signal acquisition device is used for acquiring a motor leakage magnetic signal and generating an input voltage signal, and comprises a core, a winding and a shielding shell. The signal processing module comprises a stator current frequency signal processing unit and a rotor current frequency signal processing unit. The main control unit obtains a frequency division signal by frequency division filtering of the square wave signal, obtains a single pulse signal period by mean value processing of the frequency division signal, performs maximum and minimum value filtering on a plurality of values in a sampling period and takes an average value, obtains a period value of the current frequency signal in the sampling period according to the average value, and calculates the motor speed according to the period value.

2. An electromagnetic induction based motor speed sensing device as claimed in claim 1, wherein, The signal processing module further comprises a power distribution unit, the power distribution unit comprises power conversion modules of different specifications and a voltage dividing circuit, the power conversion modules provide power supply voltage and bias voltage for elements, and the voltage dividing circuit is used for preprocessing an input voltage signal and improving an induced signal voltage.

3. An electromagnetic induction based motor speed sensing device as claimed in claim 1, wherein, The signal amplification circuit comprises an amplification filter circuit and an amplification circuit. The input signal of the signal amplification circuit passes through a filter circuit composed of a first capacitor and a first inductor. Then, the signal passes through an amplification filter circuit composed of a first operational amplifier, a first resistor, a second resistor, a second capacitor and a third capacitor, and an amplification circuit composed of a second operational amplifier, a fourth capacitor and a fifth capacitor, to obtain a sine wave signal.

4. An electromagnetic induction based motor speed sensing device as claimed in claim 1, wherein, The shaping frequency division circuit comprises a first circuit and a second circuit. The second circuit connects the filtered signal to the inverter pin 1 after optical coupling isolation, and outputs by the inverter pin 12 after twice inversion processing.

5. An electromagnetic induction based motor speed sensing device as claimed in claim 1, wherein, The rotor current frequency signal processing unit comprises an RC low-pass filter circuit, an active low-pass filter circuit and a signal amplification circuit. The RC low-pass filter circuit composed of a fourth resistor, an eighth capacitor, a fifth resistor, a ninth capacitor, a sixth resistor and a tenth capacitor, and the two first-order active low-pass filter circuits composed of a seventh resistor, an eighth resistor, an eleventh capacitor C1, a third operational amplifier, a ninth resistor, a tenth resistor, a twelfth capacitor and a fourth operational amplifier, filter out the stator frequency signal and the high-frequency noise signal; the sine wave signal of the rotor current frequency is obtained after amplification processing by the amplification circuit; the rotor current frequency signal is converted into a square wave signal after optical coupling isolation and inverter shaping processing.

6. An electromagnetic induction based motor speed sensing device as claimed in claim 5, wherein, The input signal of the amplification circuit is input to the inverting input terminal of the fifth operational amplifier through the eleventh resistor, one end of the thirteenth resistor is connected to the fifth inverting input terminal of the operational amplifier through the fourteenth resistor, and the other end is connected to the output terminal of the fifth operational amplifier, and the output terminal of the fifth operational amplifier obtains a sine wave signal.

7. An electromagnetic induction based motor speed sensing device as claimed in claim 1, wherein, Also includes a dial, according to the number of pole pairs of the motor to be measured to set different dials, the main control unit calculates the speed of the motor with different pole pairs according to the feedback of different dial combinations.

8. A method of measuring the speed of an electromagnetic induction based motor, characterized in that, It comprises: Collecting motor magnetic flux leakage signals and generating input voltage signals through induction; The collected induction signals are lifted through the voltage dividing circuit to obtain the stator current frequency signal and the rotor current frequency signal for subsequent processing; the stator current frequency signal is processed through the stator current frequency signal processing unit to obtain a square wave signal; the rotor current frequency signal is converted into a square wave signal through the rotor current frequency signal processing unit; The square wave signal is divided by frequency filtering to obtain a frequency division signal, and the frequency division signal is averaged to obtain a single pulse signal period; the maximum and minimum values of the array values in the sampling period are filtered and averaged, and the average value is obtained; the period value of the current frequency signal in the sampling period is obtained according to the average value, and the speed of the motor is calculated according to the period value.

9. A method of measuring the speed of an electromagnetic induction based motor as claimed in claim 8, wherein, The speed calculation method comprises: synchronous motor speed; The stator current frequency signal of the synchronous motor is automatically frequency-divisioned; The output frequency signal is processed by averaging to obtain a single pulse signal period; The single pulse period value obtained by processing is stored in an array and is subjected to maximum and minimum value filtering processing, and the average value of the array is obtained after multiple filtering processing; When the average value of the array is equal to each value in the array, the value is the period value of the stator current frequency signal in the sampling period, and the stator current frequency value is calculated; When the frequency values of the stator current obtained by the two channels of the shaping frequency division circuit are equal, the obtained frequency value is the frequency of the stator current in this sampling period, and according to , the rotating speed of the synchronous motor is calculated.

10. A method of measuring the speed of an electromagnetic induction based motor as claimed in claim 8, wherein, The speed calculation method also comprises: asynchronous motor speed acquisition; The rotor current frequency signal and the stator current frequency signal are respectively automatically frequency-divided and mean value processed, a single pulse signal period value is obtained and stored in an array, and the array is maximum minimum value filtered and processed, an array average value is obtained, the array average value is taken as the period value of the rotor current frequency signal and the stator current signal in the sampling period, and the rotor current frequency value and the stator current frequency value are calculated; the rotor speed of the asynchronous motor is calculated according to the formula , wherein, is the stator current frequency value, is the rotor current frequency value.

Images