Motor rotation speed measuring device and measuring method thereof

Abstract

The application relates to the technical field of motor rotating speed measurement, in particular to a motor rotating speed measurement device. The application samples and processes the high-frequency current signal of the reverse electromotive force generated by the cutting of the magnetic induction line when the rotor winding wire of the motor rotates, filters the high-frequency current signal through a filter, and obtains the corresponding motor rotating speed through analysis and calculation processing of a processor. The application has the advantages of simple design and fast analysis and calculation of the motor rotating speed. A motor rotating speed measurement method has the advantages of simple principle, low detection cost, sampling of the high-frequency current signal of the reverse electromotive force generated by the cutting of the magnetic induction line when the rotor winding wire of the motor rotates, analysis and calculation processing through a processor, measurement of the rotating speed of the motor output shaft, simple and fast measurement, and greatly reduced measurement cost.

Description

Technical Field

[0001] This invention relates to the field of motor speed measurement technology, and in particular to a motor speed measuring device and its measuring method. Background Technology

[0002] Electric motors are now ubiquitous in our daily lives. Most mechanical equipment relies on motors to perform the movements required by the machine. Therefore, the requirements for motor control technology are extremely important. In many applications, we need precise closed-loop control of motor speed to achieve target movement or tracking. This requires real-time feedback of the motor's speed. Furthermore, in open-loop control, the speed value is also needed, allowing for coarse speed control by manually adjusting the given frequency or voltage. Currently, motor speed measurement is complex, costly, and has relatively poor accuracy. Summary of the Invention

[0003] This invention addresses the problems of existing technologies by providing a motor speed measuring device and its measuring method.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A motor speed measuring device includes: (1) a current signal sampling unit: the high-frequency sinusoidal current signal corresponding to the reverse induced electromotive force generated when the motor rotor winding conductors rotate and cut magnetic field lines is sampled and processed by the current signal sampling unit to obtain motor current signal data; (2) a filter: the motor current signal data is preliminarily filtered by the filter to remove a large number of harmonic components, and the processed data is sent to the processor; (3) a processor: the processor performs debiasing processing on the received filtered data to remove the current of the motor itself, and obtains the fundamental component of the high-frequency sinusoidal current superimposed on the motor rotation current. Then, through analysis and calculation, the period value of the fundamental component of the high-frequency sinusoidal current is extracted, and the period value is filtered again to obtain a stable high-frequency current period value Tms. The speed R of the motor output shaft can be calculated by the formula. rpm .

[0006] Preferably, the sampling processing unit is a current sampling unit with a sampling frequency much higher than the frequency of the high-frequency current signal to be sampled. The sampling unit is a motor current sampling resistor connected in series in the motor drive circuit loop, or an external Hall sampling unit. The signal sampled by the sampling unit is processed by differential, amplification, filtering, and analog-to-digital conversion, and the processed data is sent to the filter for filtering.

[0007] Preferably, the processor is a microprocessor (MCU). The filter needs to perform moving average filtering on the sampled high-frequency current waveform and arithmetic average filtering on the extracted period value. The processor needs to perform debiasing processing on the filtered current signal, extract the sinusoidal fundamental period value of the current signal, and calculate the motor output shaft speed.

[0008] Preferably, the debiasing process involves first calculating the average value of the fundamental current signal within a certain time range in real time, and then subtracting the average value from the filtered current signal value to obtain the real-time debiased fundamental current signal.

[0009] Preferably, the process of extracting the period value of the fundamental component of the high-frequency sinusoidal current is to combine two methods, namely, zero-crossing detection and highest and lowest point detection, to calculate the period value of each current fundamental component.

[0010] Preferably, the formula used by the processor to calculate the motor output shaft speed is: R rpm =Bn / N2 / (2*N); where R rpm Where is the motor output shaft speed, Bn is the number of periodic waveforms of the high-frequency current signal within 1 minute, and its relationship with the period value Tms of the fundamental current component is: Bn=60*1000 / T, N2 is the reduction ratio between the motor rotor and the motor output shaft, and N is the number of magnetic poles of the motor rotor.

[0011] A method for measuring motor speed includes the following steps:

[0012] (1) Current signal sampling: The high-frequency sinusoidal current signal corresponding to the reverse induced electromotive force generated when the motor rotor winding conductors rotate and cut the magnetic field lines is sampled and processed by the current signal sampling unit to obtain the motor current signal data.

[0013] (2) Sampling current data filtering: The motor current signal data is initially filtered by a filter to remove a large number of harmonic components, and the processed data is sent to the processor; (3) Calculation of the period value of the fundamental current component: The processor performs debiasing processing on the received filtered data to remove the current of the motor itself, and obtains the high-frequency sinusoidal current fundamental component superimposed on the motor rotation current. Then, through analysis and calculation, the period value of the high-frequency sinusoidal current fundamental component is extracted. The period value is filtered again to obtain a stable high-frequency current period value Tms. The speed R of the motor output shaft can be calculated by the formula. rpm .

[0014] Preferably, the formula for the processor to analyze and process the data is: R rpm =60*1000 / T / N2 / (2*N); where R rpm(Unit: revolutions per minute) represents the motor output shaft speed; T (unit: ms) represents the period value of the fundamental current component, calculated by the processor; N2 represents the reduction ratio between the motor rotor and the motor output shaft, obtained from the motor instruction manual; N represents the number of motor rotor poles, obtained from the motor instruction manual.

[0015] The beneficial effects of this invention are:

[0016] The present invention provides a motor speed measuring device, comprising: (1) a current signal sampling unit: the high-frequency sinusoidal current signal corresponding to the reverse induced electromotive force generated when the motor rotor winding conductors rotate and cut magnetic field lines is sampled and processed by the current signal sampling unit to obtain motor current signal data; (2) a filter: the motor current signal data is preliminarily filtered by the filter to remove a large number of harmonic components, and the processed data is sent to the processor; (3) a processor: the processor performs debiasing processing on the received filtered data to remove the current of the motor itself, and obtains the fundamental component of the high-frequency sinusoidal current superimposed on the motor rotation current. Then, through analysis and calculation, the period value of the fundamental component of the high-frequency sinusoidal current is extracted, and the period value is filtered again to obtain a stable high-frequency current period value Tms. The speed R of the motor output shaft can be calculated by the formula. rpm This invention samples the high-frequency current signal when the motor is rotating and filters the high-frequency current signal. The corresponding motor rotation speed can be obtained by the processor analysis and calculation. This invention is simple in design, can quickly analyze and calculate the motor rotation speed, and has accurate and reliable detection, effectively reducing the detection cost of motor speed.

[0017] A method for measuring motor speed is disclosed. This method is simple in principle and has low testing cost. It only requires measuring the sinusoidal high-frequency current signal of the back electromotive force generated by the rotation of the motor rotor winding wires cutting magnetic field lines. The motor speed can be calculated from the period of the high-frequency current generated by the induced electromotive force. The measurement is simple and fast, which greatly reduces the measurement cost. Attached Figure Description

[0018] Figure 1 This is a framework diagram of the present invention.

[0019] Figure 2 This is a connection diagram of different sampling methods for the sampling unit of the present invention.

[0020] Figure 3 This is a flowchart of the measurement process of the present invention.

[0021] The reference numerals in the attached figures are as follows:

[0022] Motor--1, Current signal sampling unit--2, Filter--3, Processor--4. Detailed Implementation

[0023] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention. The present invention will be described in detail below with reference to the accompanying drawings.

[0024] Example 1

[0025] like Figure 1 As shown, the present invention provides a motor speed measuring device, including a current signal sampling unit 2, a filter 3, and a processor 4. The current signal sampling unit 2 is connected to the motor 1 in two ways, such as... Figure 2 As shown, the current signal sampling unit 1 samples the sinusoidal high-frequency current signal of the back electromotive force generated by the rotation of the rotor winding conductor of motor 5 cutting the magnetic field lines, and filters the sampled high-frequency current signal through filter 3. The processor 4 analyzes and calculates the filtered current signal to obtain the rotation data of motor 5. This invention samples the current signal when motor 5 rotates and filters the high-frequency current signal through filter 3. The processor 4 can then analyze and calculate the corresponding rotation speed of motor 5. This invention is simple in design, can quickly analyze and calculate the rotation speed of motor 5, and the detection is accurate and reliable, effectively reducing the detection cost of motor 5 speed.

[0026] In this embodiment, the formula for processor 4 to analyze and process data is: R rpm =60*1000 / T / N2 / (2*N); where R rpm (Unit: revolutions per minute) represents the motor output shaft speed; T (unit: ms) represents the period value of the fundamental current component, calculated by the processor; N2 represents the reduction ratio between the motor rotor and the motor output shaft, obtained from the motor instruction manual; N represents the number of motor rotor poles, obtained from the motor instruction manual.

[0027] In this embodiment, the current signal sampling unit 2 samples the sinusoidal high-frequency current signal of the back electromotive force generated by the rotation of the rotor winding conductors of motor 1 cutting the magnetic field lines. In actual detection, the rotation of motor 5 needs to drive other components to rotate, such as wheels. When other components generate friction during rotation, it has a significant impact on the sampled high-frequency current signal. Therefore, when extracting the sinusoidal fundamental period value, a combination of sine zero-crossing detection and maximum and minimum point detection can be used to obtain an accurate period value, so as to eliminate the influence of different harmonics added to the current signal when the motor is under different loads, making the detection more accurate and reliable.

[0028] In this embodiment, the processor is a microprocessor (MCU). The filter needs to perform moving average filtering on the sampled high-frequency current waveform and arithmetic average filtering on the extracted period values. The processor needs to perform debiasing processing on the filtered current signal, extract the sinusoidal fundamental wave period value of the current signal, and calculate the motor output shaft speed. The debiasing processing first calculates the average value of the fundamental current signal within a certain time range in real time, and then subtracts the average value from the filtered current signal value to obtain the real-time debiased fundamental current signal. The extraction of the period value of the high-frequency sinusoidal current fundamental component is achieved by combining zero-crossing detection and highest and lowest point detection methods on the debiased sinusoidal current fundamental to calculate each current fundamental wave period value.

[0029] Example 2

[0030] like Figure 2 As shown, a method for measuring motor speed includes the following steps:

[0031] (1) Current signal sampling: The high-frequency sinusoidal current signal corresponding to the reverse induced electromotive force generated when the motor rotor winding conductors rotate and cut the magnetic field lines is sampled and processed by the current signal sampling unit to obtain the motor current signal data.

[0032] (2) Sampling current data filtering: The motor current signal data is initially filtered by a filter to remove a large number of harmonic components, and the processed data is sent to the processor; (3) Calculation of the period value of the fundamental current component: The received filtered data is debiased to remove the current of the motor itself, and the high-frequency sinusoidal current fundamental component superimposed on the motor rotation current is obtained. Then, through analysis and calculation, the period value of the high-frequency sinusoidal current fundamental component is extracted. The period value is filtered again to obtain a stable high-frequency current period value Tms. The speed R of the motor output shaft can be calculated by the formula. rpm .

[0033] In this embodiment, the formula for the processor to analyze and process the data is: R rpm =60*1000 / T / N2 / (2*N); where R rpm (Unit: revolutions per minute) represents the motor output shaft speed; T (unit: ms) represents the period value of the fundamental current component, calculated by the processor; N2 represents the reduction ratio between the motor rotor and the motor output shaft, obtained from the motor instruction manual; N represents the number of motor rotor poles, obtained from the motor instruction manual.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the present invention without departing from the scope of the present invention are within the scope of the present invention.

Claims

1. A motor speed measuring device, characterized in that, include: (1) Current signal sampling unit: The high-frequency sinusoidal current signal corresponding to the reverse induced electromotive force generated when the motor rotor winding conductors rotate and cut the magnetic field lines is sampled and processed by the current signal sampling unit to obtain the motor current signal data. (2) Filter: The motor current signal data is initially filtered by the filter to remove a large number of harmonic components, and the processed data is sent to the processor. (3) Processor: The processor performs debiasing processing on the received filtered data, removes the current of the motor itself, and obtains the fundamental component of the high-frequency sinusoidal current superimposed on the motor's rotating current. Then, through analysis and calculation, it extracts the period value of the fundamental component of the high-frequency sinusoidal current, and performs filtering processing on the period value again to obtain a stable high-frequency current period value Tms. The speed Rrpm of the motor output shaft can be obtained by formula calculation. The processor is a microprocessor (MCU). The filter needs to perform moving average filtering on the sampled high-frequency current waveform and arithmetic average filtering on the extracted period value. The processor needs to perform debiasing processing on the filtered current signal, extract the sinusoidal fundamental period value of the current signal, and calculate the motor output shaft speed. The formula for calculating the motor output shaft speed by the processor is: Rrpm=Bn / N2 / (2*N); where Rrpm is the motor output shaft speed, Bn is the number of periodic waveforms of the high-frequency current signal within 1 minute, and its relationship with the period value Tms of the fundamental current component is: Bn=60*1000 / T, N2 is the reduction ratio between the motor rotor and the motor output shaft, and N is the number of magnetic poles of the motor rotor.

2. The motor speed measuring device according to claim 1, characterized in that: The sampling processing unit is a current sampling unit with a sampling frequency much higher than the frequency of the high-frequency current signal to be sampled. The sampling unit is a motor current sampling resistor connected in series in the motor drive circuit loop, or an external Hall sampling unit. The signal sampled by the sampling unit is processed by differential, amplification, filtering, and analog-to-digital conversion, and the processed data is sent to the filter for filtering.

3. The motor speed measuring device according to claim 1, characterized in that: The debiasing process involves first calculating the average value of the fundamental current signal within a certain time range in real time, and then subtracting the average value from the filtered current signal value to obtain the real-time debiased fundamental current signal.

4. The motor speed measuring device according to claim 1, characterized in that: The process of extracting the period value of the fundamental component of the high-frequency sinusoidal current involves combining two methods: zero-crossing detection and highest and lowest point detection, to calculate the period value of each fundamental component of the current.

5. A method for measuring motor speed using a motor speed measuring device as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Current signal sampling: The high-frequency sinusoidal current signal corresponding to the reverse induced electromotive force generated when the motor rotor winding conductors rotate and cut the magnetic field lines is sampled and processed by the current signal sampling unit to obtain the motor current signal data. (2) Sampling current data filtering: The motor current signal data is initially filtered by the filter to remove a large number of harmonic components, and the processed data is sent to the processor. (3) Calculation of the period value of the fundamental component of the current: The processor performs debiasing processing on the received filtered data, removes the current of the motor itself, and obtains the fundamental component of the high-frequency sinusoidal current superimposed on the motor rotation current. Then, through analysis and calculation, the period value of the fundamental component of the high-frequency sinusoidal current is extracted. The period value is filtered again to obtain a stable high-frequency current period value Tms. The speed Rrpm of the motor output shaft can be obtained by calculation using the formula.

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