CN208461724U - Portable electronic magnetic linkage torque tester - Google Patents

Abstract

The utility model relates to a portable electronic flux linkage torque tester. The torque tester is internally provided with a processor (1), and the processor (1) detects the current of a motor (9) under test through a current sensor (2), The voltage of the motor (9) under test is detected by the voltage transformer (3), the current signal of the motor measured by the current sensor (2) and the voltage signal of the motor measured by the voltage transformer (3) are passed through the filter (4). The signal is conditioned and filtered into the processor (1). The torque tester is easy to carry, small in size and light in weight, and can be applied to most motors. The current of the motor under test can be measured through the non-contact Rogowski coil, and the original signal of the stator current can be obtained. The voltage transformer can measure The original voltage signal of the motor is then processed by a filter and then sent to the processor for processing and calculation. The obtained motor torque error is small and the precision is high.

Description

Portable Electronic Flux Torque Tester

technical field

The utility model relates to a test device, in particular to a portable electronic flux linkage torque tester, which is used for on-site efficiency detection of motor torque.

Background technique

With the intensification of energy shortage and greenhouse effect, the development and utilization of clean energy, energy conservation and emission reduction have become the focus of attention of all countries in the world. For China, which is short of resources and has a large population, energy saving is particularly necessary. Small and medium-sized three-phase asynchronous motors are the most widely used products with high energy consumption, and their application range covers all fields of the national economy. And the operating efficiency of the motor is generally low, so it is of great significance to improve the operating efficiency of the motor. There are many reasons for the low operating efficiency of the motor, including the problems of the motor itself, but more importantly, the use of problems, such as low load rate, motor aging and so on. There are many ways to solve this problem, such as promoting the use of high-efficiency motors, replacing motors with significantly low operating efficiency, or improving the operating efficiency of motors through appropriate control methods. To achieve this goal, it is first necessary to accurately detect the actual operating efficiency of the motor without interfering with the normal operation of the motor. Traditional testing methods based on laboratory environment cannot be directly used for field testing, because no-load test, short-circuit test, stator resistance test, rotational speed test and torque test are difficult to complete in field conditions.

For large motors, an on-line motor status monitoring system is often equipped, which can generally detect the operating efficiency of the motor. For small and medium-capacity motors, from the perspective of cost, a monitoring system is generally not equipped. The small and medium-capacity motors account for the vast majority of the motors in use in terms of quantity and power consumption. On-line monitoring of all small and medium motors is almost impossible, and this work must be done by field staff. For this reason, it is necessary to develop a low-cost field efficiency detection device suitable for small and medium motors. On-site personnel generally hope that the operation of the detection device is as simple as possible, small in size, light in weight, and easy to carry.

The usual portable detection device is a handheld infrared or laser sensor. Compared with the photoelectric encoder, its price is low, and it does not need to be installed on the motor. The operation is simple, and it is more practical for small and medium-sized and low-power motors. However, for those large motors that cannot observe the motor shaft, such sensors will not be used, and infrared or laser sensors have low measurement accuracy and often cannot meet the requirements of high-precision test systems. After comprehensive consideration, it is found that for the field portable motor test system, it is unreliable to use the sensor to directly obtain the motor torque. Therefore, it is of great significance to study the sensorless motor torque online identification algorithm for obtaining high-precision motor torque results.

Utility model content

In order to solve the technical problems existing in the background art, the utility model provides a portable electronic flux linkage torque tester that is lightweight, portable, convenient and practical, and has high measurement accuracy.

The technical scheme adopted by the utility model to solve its technical problems is:

A portable electronic flux linkage torque tester, the top of the shell of the torque tester has a hole for wiring out, and is used for wiring with the motor under test. Detect the current of the motor under test, and use the voltage transformer to detect the voltage of the motor under test. The current signal of the motor measured by the current sensor and the voltage signal of the motor measured by the voltage transformer are subjected to signal conditioning and filtering in the filter. Input processing In the device, the processor includes a microprocessing module, and the microprocessing module is connected with a data acquisition module and a data processing module, wherein the data acquisition module is connected with the current sensor and the voltage transformer, and the data acquisition module passes the collected data through the microcomputer. The processing module is sent to the data processing module, the processor is also provided with a display module, a keyboard module and a signal processing module, the processor sends the calculated motor torque adjustment value to the control module through the signal processing module, and the control module Connected to the motor under test, it can control the action of the motor under test.

The surface of the casing of the torque tester is provided with a display screen and various buttons for control.

The processor is an ARM microcontroller.

The current sensor is a Rogowski coil.

The beneficial effects of the present utility model:

This portable electronic flux linkage torque tester is easy to carry, small in size and light in weight, and can be applied to most motors. The current of the motor under test can be measured through a non-contact Rogowski coil, and the original signal of the stator current, voltage can be obtained. The transformer can measure the original voltage signal of the motor, and then send it to the processor for processing and calculation after being processed by the filter. The obtained motor torque error is small and the precision is high.

In addition, the online identification algorithm adopted by this portable electronic flux linkage torque tester has the following advantages:

(1) Based on the traditional torque meter method, a sensorless torque online identification method is proposed to replace the role of the original torque sensor to obtain the torque parameters required to calculate the motor efficiency.

(2) In the research of the sensorless motor torque identification algorithm, the method of estimating the motor shaft end torque through the air-gap torque is adopted, which improves the identification accuracy, has a simple structure, is easy to implement, and has a higher identification accuracy of the stator flux linkage.

(3) This patent adopts the air-gap torque calculation formula under the rotating coordinate system, and performs Clark transformation and Park transformation on the three-phase voltage and current respectively, and transforms from the three-phase static coordinate system to the two-phase rotating coordinate system. At the same time, the voltage , current, and stator flux linkage are also converted from alternating current to direct current. Matlab/Simulink simulation and experimental results show that the identification error of the motor energy efficiency detection method proposed in this patent is less than 1%, which shows the effectiveness and feasibility of the method.

Description of drawings

The utility model will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the outline structure diagram of the portable electronic flux linkage torque tester of the present invention.

FIG. 2 is a schematic diagram of the portable electronic flux linkage torque tester of the present invention.

FIG. 3 is a schematic diagram of the internal modules of the processor in FIG. 2 .

FIG. 4 is a Simulink simulation schematic diagram of the stator flux linkage observer based on the low-pass filter of the present invention.

Figure 5 is a schematic diagram of the Park transformation in the Simulink simulation in Figure 4.

FIG. 6 is a diagram showing the identification result of the simulation of the stator flux linkage observer based on the low-pass filtering of the present invention.

FIG. 7 is a comparison diagram of the simulation results of the stator flux linkage observer based on the low-pass filtering method of the present invention and the novel integral method.

FIG. 8 is a diagram showing the calculation result of the stator flux linkage in the two-phase stationary coordinate system based on the low-pass filtering method of the present invention.

FIG. 9 is a diagram of the stator flux linkage and stator current under the alpha-beta-0 coordinate of the utility model performing Park transformation to obtain the stator flux linkage and stator current under the two-phase rotating coordinate system.

FIG. 10 is a comparison diagram of the measured torque and the estimated torque of the motor of the present invention.

In the figure: processor 1, microprocessor module 1.1, data acquisition module 1.2, data processing module 1.3, current sensor 2, voltage transformer 3, filter 4, display module 5, keyboard module 6, signal processing module 7, control module 8. Motor under test 9.

Detailed ways

The present utility model will be described in further detail below in conjunction with the accompanying drawings.

The utility model relates to a portable electronic flux linkage torque tester. Referring to FIG. 1 , the top of the shell of the portable electronic flux linkage torque tester has an opening to allow wires to be connected out. There is a display screen and a variety of buttons for control.

This portable electronic flux linkage torque tester is internally provided with a microcontroller, see Figure 2, this portable electronic flux linkage torque tester mainly includes a processor 1, the processor 1 is an ARM microcontroller, and the processor 1 The current of the motor 9 under test is detected by the current sensor 2, and the voltage of the motor is measured by the voltage transformer 3. The motor 9 under test is the most widely used three-phase AC asynchronous motor, the current sensor 2 is a Rogowski coil, and the Rogowski coil is also It is called a current measurement coil. The measurement principle is based on Faraday's law of electromagnetic induction. The output signal is the differential of current to time, and then the real current signal can be restored through an integrating circuit. The advantage is that it does not contain magnetic materials and has no hysteresis effect. The phase error is almost zero, and there is no saturation phenomenon. The measurement range is from several amperes to hundreds of amperes. Compared with traditional current transformers, it has the advantages of wide measurement range, high measurement accuracy and fast response speed. It is suitable for occasions with high current accuracy. , the current signal of the motor measured by the current sensor 2 and the voltage signal of the motor measured by the voltage transformer 3 are input into the processor 1 after signal conditioning and filtering in the filter 4 .

Referring to FIG. 3 and FIG. 4 , the processor 1 includes a micro-processing module 1.1, and the micro-processing module 1.1 is connected with a data acquisition module 1.2 and a data processing module 1.3, wherein the data acquisition module 1.2 is connected with the current sensor 2 and the voltage transformer. 3 are connected to collect voltage and current parameters, the data acquisition module 1.2 sends the collected data to the data processing module 1.3 through the micro-processing module 1.1, and the data processing module 1.3 processes the data, and the processor 1 is also provided with a display module 5. The keyboard module 6 and the signal processing module 7, the processor 1 can send the calculated motor torque adjustment value to the control module 8 through the signal processing module 7, and the control module 8 is connected with the tested motor 9, and can control the measured motor torque. Action of the motor 9.

In addition, the processor 1 can identify and calculate the motor torque online through an optimized air-gap torque-based method, and the obtained motor torque has a smaller error and higher precision.

Among them, the role of electromagnetic force and the generation of electromagnetic torque:

The electromagnetic torque generated by the axial electromagnetic force of the rotor of the rotating motor is an important factor in the electromechanical energy conversion of the motor. Considering the actual structure of the motor rotor, the electromagnetic force acts not only on the rotor winding, but also on the rotor core of the motor. Therefore, this patent describes the generation of electromagnetic force and electromagnetic torque based on the electromagnetic field theory.

When the three-phase windings of the stator are fed with symmetrical three-phase currents, a rotating magnetic field will be generated. Under the action of the rotating magnetic field, the motor rotor will generate induced electromotive force and induced current, thereby generating electromagnetic force and electromagnetic torque. The generation of the electromagnetic force can be explained by the Lorentz force of the electric charge in the magnetic field from a microscopic point of view. According to the electromagnetic field theory, the electromagnetic force acting on the unit volume of the magnetic object in the magnetic field can be calculated by the following formula:

where f is the electromagnetic force acting on the volume element;

H is the magnetic field strength at the volume element;

i is the current density at the volume element;

J0 is the permanent magnetization at the volume element;

Ur is the permeability at the volume element.

In the above formula, the first term is the force on the current-carrying conductor in the magnetic field, the second term is the force generated by the uneven magnetic saturation in the iron core or the boundary between the magnetic material and the air, and the third term is the permanent magnet. the force received.

The main modes of action of these forces are as follows:

(1) Acting on the stator winding, that is, the first item in the above formula.

(2) Acting on the surface of the iron core, that is, the boundary between the magnetic material and the air is generated.

(3) Acting on the inside of the iron core, including the uneven magnetic saturation of the iron core and the force on the permanent magnet.

Finally, the electromagnetic torque can be obtained through the electromagnetic force and its action vector. However, if the electromagnetic force and electromagnetic torque are obtained by this method, it is necessary to obtain the structural parameters of the motor. Generally, these parameters are difficult to obtain, so this method has great limitations and cannot be applied to the calculation of the motor torque in the field.

At home and abroad, the torque information of the motor is generally obtained through the torque sensor, and the sensor is installed between the motor under test and the load motor. However, this method is not only expensive, but also difficult to install. It also interferes with the operation of the motor during testing. It should not be used in On-site motor torque measurement. Therefore, many scholars have devoted themselves to the research of sensorless torque identification technology. After decades of research, this technology has developed rapidly. At present, there are mainly neural network method, extended Kalman filter method and air-gap torque method. .

In this patent, the method based on the air gap torque is used to identify the motor torque online. According to the structure of the motor, there is a thin layer of gap between the stator and the rotor, which is called the air gap. This method only needs the voltage and current input at the motor terminal to calculate the electromagnetic torque, which is simpler and easier to implement than the traditional method. Among them, in the air-gap torque method, the key to solving the air-gap torque is to calculate the motor stator flux linkage value. At present, there are mainly two methods in the identification of motor stator flux linkage at home and abroad: the traditional pure integral method and the new stator flux linkage observer. The traditional pure integral method is simple in structure and convenient in calculation, and has very low hardware requirements, but the calculation accuracy often fails to meet the requirements. New-type stator flux observers are generally based on filter algorithms, such as stator flux observers based on low-pass filters. This method has a complex structure, high hardware requirements, but high calculation accuracy. The stator flux linkage observer based on the pass filter method is used to identify the motor torque online.

1) Stator flux linkage observer based on low-pass filtering method

It can be seen from the above analysis that to obtain the electromagnetic torque of the motor, it is necessary to obtain the flux linkage information of the motor. Since the traditional pure integral calculation of the stator flux linkage will bring great errors, in view of the disadvantage of the integral method in calculating the stator flux linkage, in this section, a low-pass filter is used to replace the pure integral link, and the calculation results are compared with the integral method. To find the most suitable stator flux linkage calculation method for the subsequent calculation of air gap torque.

The space vector expression of the stator flux linkage based on the voltage model is:

in, are the voltage, current, flux linkage and induced electromotive force vector respectively in the static coordinate system of the motor, e _s is the back electromotive force, and Es the phase angle and amplitude of the induced electromotive force vector, ω _e is the stator angular frequency.

Considering the zero-drift of voltage and current and the initial value of integral during measurement, the traditional integral method makes the observation result have a DC bias problem, and a low-pass filter is used to replace the pure integral link. The expression of the stator flux linkage is:

Among them, ω _c is the cutoff frequency of the low-pass filter, ψ _s is the actual flux linkage, and ψ' _s is the estimated flux linkage.

In order to eliminate the steady-state error introduced by the low-pass filter, it is necessary to perform amplitude and phase compensation on the result after the low-pass filter. G is a compensation vector function, so there is the following formula.

ψ' _s G=ψ _s 3.41

in:

On the basis of the stator flux linkage observer based on the traditional low-pass filter, a new improved low-pass filter algorithm is proposed, that is, the calculation order of the amplitude and phase compensation and the low-pass filter is exchanged, that is, the amplitude and phase compensation is performed first. , and then calculated by the low-pass filter, it can be seen from the formula that the amplitude and phase compensation of the induced electromotive force need to be performed first, namely:

E _'s G=Es _3.44

In order to simplify the calculation and reduce the structure of the hardware, it is necessary to perform Clark transformation on the stator voltage and current before performing the amplitude and phase compensation, and transform from the three-phase static a-b-c coordinate system to the two-phase static α-β-0 coordinate system, namely:

Therefore, the expression of the induced electromotive force in the two-phase stationary α-β-0 coordinate system is:

Substitute into the formula to get:

Among them, u _sα , u _sβ , is _sα , is _sβ are the voltage and current components in the stationary α-β-0 coordinate system of the motor, and _es α , _es β are the components of the actual motor back EMF under the stationary α-β-0 coordinate system , e' _sα , e' _sβ are the estimated components of the motor back EMF in the two-phase stationary α-β-0 coordinate system. The formula is the new low-pass filter stator flux observer algorithm.

The Simulink simulation schematic is shown in Figure 4.

Transformed by Park, we get

In formula 3.46, it is necessary to determine the size of the synchronous angular velocity θ when performing the Park transformation. This is not easy to obtain the voltage and current data obtained in the real-time acquisition state. Therefore, in this patent, the relationship between the synthetic flux linkage and the component flux linkage is used to determine the value of θ. value, as follows:

In Simulink, the schematic diagram of the Park transformation is shown in Figure 5.

Therefore, the electromagnetic torque Te of the motor is:

where p is the number of pole pairs of the motor.

2) Simulation of stator flux linkage observer based on low-pass filtering

In order to verify the accuracy of the torque online identification algorithm proposed in this patent, a simulation of the stator flux linkage observer based on low-pass filtering is established in Matlab/Simulink. The motor power supply is 220V AC and the frequency is 50Hz.

The simulation results are basically consistent with the estimated flux linkage of this algorithm and the theoretical flux linkage, as shown in Figure 6, which shows the effectiveness of the algorithm.

In order to find the most suitable stator flux linkage calculation method for the motor energy efficiency calculation of this patent, the simulation results of the stator flux linkage observer based on the low-pass filtering method proposed in this patent and the new integral method are compared, and the results are shown in Figure 7. Show. It can be seen from the figure that compared with the new integral method, the identification accuracy of the low-pass filtering method is very high. After the motor runs stably, the identification error is basically 0, while the error of the new integral method fluctuates greatly. In an accurate case, the low-pass filtering method has obvious advantages and is easy to implement in hardware, so this patent uses a stator flux linkage observer based on the low-pass filtering method to calculate the stator flux linkage.

The motor air-gap torque is determined by Equation 3.48, so the calculation of the air-gap torque requires the stator flux linkage ψ _d , ψ _q and the stator current _id , i _q in the two-phase rotating coordinate system dq-0, so it is necessary to The voltage and current are Clark transformed and Park transformed. Since the voltage and current obtained by the motor measurement module in Matlab/Simulink are in the two-phase static coordinate system alpha-beta-0, only Park transformation is required during simulation. Simulink-based motor torque online identification algorithm simulation, the actual torque of the motor is collected by oscilloscope for result verification.

The identification result of stator flux linkage based on the low-pass filtering method is shown in Fig. 8.

The stator flux linkage and stator current in the alpha-beta-0 coordinate are Parked to obtain the stator flux linkage and stator current in the two-phase rotating coordinate system, as shown in Figure 9. It can be seen from the figure that the motor runs stably when the motor is running stably. Afterwards, both the stator flux linkage and the stator current components become DC quantities.

By substituting the stator flux linkage and stator current obtained after Park transformation into Equation 3.51, the air-gap torque of the motor can be obtained and compared with the actual torque. The comparison results are shown in Figure 10 and Table 1. After experiencing a brief shock at startup, the torque of the motor tends to be stable after running for about 1s. In the figure, the solid line represents the measured torque, and the dashed line represents the estimated torque. It can be seen from the simulation results that the torque curve obtained by using the torque online identification algorithm proposed by this patent is almost completely consistent with the actual torque curve, indicating that this algorithm reliability.

From the analysis of the results in Table 1, it can be seen that the air gap torque calculated by this algorithm in the simulation is 1.4934Nm, the actual torque is 1.4936Nm, the error is 0.0002Nm, and the relative error is 0.01%. The results verify the algorithm proposed in this patent. The high precision and effectiveness can be used for the calculation of motor efficiency.

Table 1 Error analysis of torque identification algorithm

Therefore, the motor torque obtained by the above-mentioned optimized air-gap torque-based online identification method has high accuracy and small error.

Taking the above ideal embodiment according to the present invention as inspiration, through the above description, relevant staff can make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present utility model is not limited to the content in the description, and its technical scope must be determined according to the scope of the claims.

Claims (4)

1. The utility model provides a portable electron flux linkage torque tester which characterized in that: the torque tester is characterized in that a hole is formed in the top of a shell of the torque tester to lead out a wire for connecting with a tested motor (9), a processor (1) is arranged in the torque tester, the processor (1) detects the current of the tested motor (9) through a current sensor (2), the voltage of the tested motor (9) is detected through a voltage transformer (3), a current signal of the motor detected by the current sensor (2) and a voltage signal of the motor detected by the voltage transformer (3) are input into the processor (1) after signal regulation and filtering in a filter (4), the processor (1) comprises a micro-processing module (1.1), the micro-processing module (1.1) is connected with a data acquisition module (1.2) and a data processing module (1.3), wherein the data acquisition module (1.2) is connected with the current sensor (2) and the voltage transformer (3), and the data acquisition module (1.2) transmits acquired data to the data processing module (1.3) through the micro-processing module (1.1), the processor (1) is also provided with a display module (5), a keyboard module (6) and a signal processing module (7), the processor (1) sends the calculated motor torque adjusting value to the control module (8) through the signal processing module (7), and the control module (8) is connected with the motor to be tested (9) and can control the action of the motor to be tested (9).

2. A portable electronic flux linkage torque tester as claimed in claim 1, wherein: the surface of the shell of the torque tester is provided with a display screen and a plurality of buttons for control.

3. A portable electronic flux linkage torque tester as claimed in claim 1, wherein: the processor (1) is an ARM microcontroller.

4. A portable electronic flux linkage torque tester as claimed in claim 1, wherein: the current sensor (2) is a Rogowski coil.