CN116482532A - Double-machine clutch type testing device and method for measuring mechanical loss of variable frequency motor - Google Patents
Double-machine clutch type testing device and method for measuring mechanical loss of variable frequency motor Download PDFInfo
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Abstract
The invention discloses a double-machine clutch type testing device and a method for measuring the mechanical loss of a variable frequency motor, wherein the double-machine clutch type testing device comprises two identical variable frequency motors, a rotating speed measuring unit, a power measuring unit and a driving control unit, wherein any variable frequency motor is used as a driving motor, the other variable frequency motor is a load motor, and the driving motor is always in a power-off state in the whole testing process, and is separated from or connected with the load motor through a coupler so as to realize no-load or load; when the driving motor is connected with the load motor, the input active power of the driving motor running at different rotating speeds and loads is measured through the rotating speed measuring unit and the power measuring unit; when the driving motor is separated from the load motor, the input active power of the driving motor which runs at different rotation speeds in a idle mode is measured; the change of the input active power measured value of the same rotating speed and empty load operation of the driving motor is the corresponding rotating speed mechanical loss. The invention has the advantages of relatively simple measurement process and experimental data processing process, high measurement efficiency, high measurement precision and the like.
Description
Technical Field
The invention mainly relates to the technical field of motor testing, in particular to a double-machine clutch type testing device and method for measuring mechanical loss of a variable frequency motor.
Background
The current global resource energy shortage crisis and environmental pollution problems are becoming more serious due to the rapid development of the human industry, the uncontrolled emission of industrial pollutants and the over exploitation and utilization of resource energy in the past few decades. It is counted that the industrial electricity in the world currently occupies more than 70% of the total electricity consumption in the world. The electrical energy required for industrial production is mainly consumed by the motor. The motor is used as a power source and is indirectly driven by a transmission system or directly drives the actuating mechanism to work or run without the transmission system. The variable frequency speed regulating motor (called variable frequency motor for short) is a motor for realizing stepless speed regulation by utilizing electromagnetic induction or action and a variable frequency speed regulating principle, and has the outstanding technical advantages of compact structure, small volume, high power density, high transmission efficiency, high efficiency, energy saving, wide speed regulating range, small vibration noise, low failure rate, on-line or remote accurate control and the like, and is widely applied to the fields of aerospace, high-speed precision machine tools, high-speed fan compressors, new energy electric automobiles and the like because intermediate transmission links such as belts, chains and the like are omitted structurally. The variable frequency motor is an important direction for research, development, design, production, application and development of the current motor because of high efficiency, energy conservation and environmental protection, and has very important strategic significance for relieving the current resource energy shortage crisis and environmental pollution problem.
The mechanical loss is used as a main loss of the variable frequency motor, is the power consumed by the motor to overcome the friction work of the rotor, and has important influence on the energy consumption, efficiency, force performance characteristics and comprehensive performance of the motor. The traditional measuring method cannot adapt to the mechanical loss measurement requirement of the variable frequency motor for various reasons, the influence on the technical development of the variable frequency motor cannot be ignored, and a new method needs to be researched and explored.
The traditional no-load constant-speed transformation method is a common method for measuring the mechanical loss of a common 50Hz power frequency induction motor. The method comprises the following specific implementation processes: 1. a voltage regulator is connected between the tested motor and a 50Hz three-phase sinusoidal alternating current power supply, and the output voltage of the voltage regulator is adjustable within a certain range. 2. The tested motor is started directly under no load at the rated voltage (380V) and the rated frequency (50 Hz), and is fully idle until the mechanical loss is stable. 3. And after the mechanical loss is stable, measuring the input voltage, the input current and the input active power of the tested motor under different power supply voltage conditions. The input voltage of the tested motor is changed by adjusting the output voltage of the voltage regulator, the input voltage of the tested motor is gradually reduced from 1.25 times of rated voltage until the input current of the tested motor is minimum or unstable rising starts to occur, but the power supply frequency of the tested motor is always 50Hz in the voltage regulation and idle running test process, so that the rotating speed or mechanical loss of the tested motor is always kept constant in the test process. 7-9 measuring points are taken, and each measuring point is used for measuring three-phase input voltage, three-phase input current and input active power of a stator winding of the tested motor. In order to reduce random errors in the measuring process, the average value of the multiple measuring results of each measuring point is taken. 4. And stopping the machine to measure the resistance of the stator winding of the tested motor. And 3, stopping the operation of the tested motor after the measurement is completed, and immediately measuring the resistance of the stator winding of the tested motor after the stop, so that the influence of the temperature on the measurement result is reduced as much as possible. 5. And (3) based on the measurement results of the steps (3) and (4), indirectly obtaining the measurement value of the copper loss of each measuring point and the measurement value of the loss of the deducted copper loss through calculation. And on the basis of the three-phase input current of the stator winding of the tested motor measured at each measuring point and the resistance measured value of the stator winding during shutdown, the copper loss measured value of each measuring point is indirectly obtained through calculation of a copper loss formula. And subtracting the corresponding copper loss measurement value from the input active power measured at each measuring point to obtain a loss measurement value of each measuring point deducting copper loss. 6. And drawing a idle operation input active power curve and a loss curve deducting copper loss of the tested motor by adopting coordinate paper. The horizontal axis represents the change of input voltage, the vertical axis represents the change of input active power and loss (containing mechanical loss and iron loss components) with copper loss deduction, and a curve of the change of the input active power and the loss with copper loss deduction of the idle operation of the tested motor along with the input voltage is drawn in the same coordinate system by adopting a coordinate paper. 7. And (3) obtaining a test result of the mechanical loss of the tested motor by extending the two curves to obtain an intersection point on the basis of the two curves drawn in the step (6). The two curves are intersected on the vertical axis (the input voltage of the tested motor is zero at the moment), and the vertical coordinate value of the intersection point is the test result of the mechanical loss of the tested motor.
The no-load constant-speed transformation method can eliminate electromagnetic loss from the measurement principle, realizes mechanical loss separation, has higher reliability of measurement results, but is not applicable to the measurement of the mechanical loss of the variable frequency motor, and is characterized in that:
1. the method principle is not applicable. The idle constant-speed voltage transformation method measurement principle requires that the tested motor runs idle at a constant rotation speed and simultaneously requires that the input voltage of the tested motor is changed to perform multi-measuring-point multi-physical-quantity measurement, so as to obtain the idle running input active power of the tested motor and a change curve of the loss of copper loss with the input voltage, and obtain the test result of the mechanical loss of the tested motor by prolonging the two curves to obtain an intersection point. Compared with a common 50Hz power frequency motor, the variable frequency motor adopts an inverter to drive and control speed regulation, but no matter in which control speed regulation area, once the power supply frequency or the rotating speed is determined, the output voltage of the inverter or the input voltage of the motor can not be changed. In a constant torque control speed regulation area with rated rotation speed and below, the output voltage of the inverter is in direct proportion to the power supply frequency, and the frequency conversion is performed, and the voltage is also changed, but once the power supply frequency of the inverter or the rotation speed of the motor is determined, the output voltage of the inverter or the input voltage of the motor is also determined uniquely; in the constant power field weakening control speed regulation area above the rated rotation speed, the output voltage of the inverter reaches the maximum value and remains unchanged all the time, and is always equal to the rated voltage of the motor. For the above reasons, the measurement principle of the no-load constant-speed transformation method is not suitable for measuring the mechanical loss of the variable frequency motor.
2. The measurement process and the experimental data are complex to process, and the measurement efficiency is low. The points to be measured and the physical quantity to be measured are more at the same rotating speed, and three-phase input voltages, three-phase input currents and input active power of 7-9 points are usually measured. Moreover, a series of post-processing of the measured raw experimental data is also required, including: copper loss calculation of each measuring point, loss calculation of deducting copper loss, drawing a change curve of idle input active power of a tested motor and loss of deducting copper loss along with input voltage, and prolonging the two curves to obtain an intersection point. In short, the measurement process and the experimental data are relatively complicated to process, and the measurement efficiency is low.
3. The test result of the mechanical loss of the tested motor is obtained by drawing and prolonging the mode of obtaining the intersection point, and the measurement accuracy is affected. The test result of the mechanical loss of the tested motor is obtained by drawing a change curve of the idle input active power of the tested motor and the loss of deducted copper loss along with the input voltage and obtaining an intersection point by extending the two curves. The method can theoretically separate out mechanical loss, but in practice, certain errors are caused because: on one hand, the two curve extension parts are not supported by experimental data; on the other hand, the law of change of the extension parts of the two curves is not clear theoretically. The two uncertainty factors can influence the specific position of the intersection point of the two curves, so that the actual intersection point of the two curves is not coincident with the theoretical intersection point or deviates from the theoretical intersection point (the input voltage of the tested motor at the theoretical intersection point is zero, the input current is also zero, the electromagnetic loss can be completely eliminated just, and the mechanical loss separation is realized).
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the problems existing in the prior art, the invention provides a double-machine clutch type testing device and method for measuring the mechanical loss of a variable frequency motor, wherein the measuring process and the experimental data processing process are relatively simple, and the measuring efficiency is high.
The double-machine clutch type testing device for measuring the mechanical loss of the variable frequency motor comprises two identical variable frequency motors, a rotating speed measuring unit, a power measuring unit and a driving control unit, wherein one variable frequency motor is a driving motor, the other variable frequency motor is a load motor, and the driving motor is separated from or connected with the load motor through a coupler so as to realize the mechanical clutch of the driving motor and the load motor or the empty load of the driving motor; wherein the load motor is always in a non-energized state;
when the driving motor is connected with the load motor through a coupler, the rotating speed of the driving motor is measured through the rotating speed measuring unit, and the load input active power of the driving motor under the corresponding rotating speed is measured through the power measuring unit;
when the driving motor is separated from the load motor through a coupler, the rotating speed of the driving motor is measured through the rotating speed measuring unit, and the idle input active power of the driving motor under the corresponding rotating speed is measured through the power measuring unit;
the driving control unit is connected with the driving motor and is used for driving the driving motor and controlling variable frequency speed regulation, so that the driving motor can randomly change the rotating speed within the speed regulation range for testing;
the driving control unit is respectively connected with the rotating speed measuring unit and the power measuring unit and is used for obtaining the mechanical loss of the variable frequency motor according to the active power input by the load and the active power input by the idle load.
Preferably, the drive motor is always connected to the coupling during testing to eliminate the effect of coupling wind friction loss on the measurement results.
Preferably, the rotation speed measuring unit comprises a speed sensor for measuring a rotation speed signal of the driving motor and a signal conditioning box for amplifying and filtering the rotation speed signal.
Preferably, the power measurement unit comprises a current sensor, a voltage sensor and a power measurement analyzer, wherein the current sensor is used for measuring the input current of the driving motor; the voltage sensor is used for measuring the input voltage of the driving motor, and the power measurement analyzer is respectively connected with the current sensor and the voltage sensor and used for obtaining the input active power of the driving motor according to the measured input voltage, input current and power factor of the driving motor.
The invention also discloses a testing method based on the double-machine clutch type testing device for measuring the mechanical loss of the variable frequency motor, which comprises the following steps:
the driving motor is connected with the load motor through a coupler, and the load input active power of the driving motor running at different rotating speeds under the load is measured;
the driving motor is separated from the load motor through a coupler, and idle input active power of the driving motor at different rotation speeds is measured;
and the difference value of the active power input by the load and the active power input by the idle load, which are measured under the same rotating speed condition, is the mechanical loss test result of the driving motor at the corresponding rotating speed.
Preferably, the specific process of measuring the load input active power is as follows:
the driving motor is connected or coupled in series with the non-energized load motor through a coupler, so that the driving motor is in a load state;
the driving motor carries out load voltage-dropping frequency-reducing soft start through the inverter, and the rotating speed of the driving motor is increased to the target measuring rotating speed by adjusting the power supply frequency of the inverter;
the driving motor fully loads and operates to the stable mechanical loss at the target measurement rotating speed, and after the mechanical loss is stable, the rotating speed of the driving motor load operation and the corresponding load input active power are respectively measured through the rotating speed measuring unit and the power measuring unit; changing the target measurement rotating speed, and repeating the steps to obtain the load input active power at different rotating speeds.
Preferably, the specific process of measuring the idle input active power is as follows:
the non-energized load motor is not connected with or separated from the coupler so as to enable the driving motor to be in an idle state;
the driving motor carries out no-load voltage-reducing frequency-reducing soft start through the inverter, and the rotating speed of the driving motor is increased to the target measuring rotating speed by adjusting the power supply frequency of the inverter;
the driving motor is fully idle running to stable mechanical loss at a target measurement rotating speed, and the idle running rotating speed of the driving motor and corresponding idle input active power are respectively measured through a rotating speed measuring unit and a power measuring unit after the mechanical loss is stable; changing the target measurement rotating speed, and repeating the steps to obtain the idle input active power at different rotating speeds.
In the test process, the driving motor selects a constant torque control mode in a speed regulation area with the rated rotation speed or below, and selects a constant power flux weakening control mode in a speed regulation area with the rated rotation speed or above.
The three-phase input current of the driving motor running at the same rotation speed and the stator winding phase resistance during the shutdown are measured, and then the influence caused by the current and copper loss change before and after the loading of the driving motor is eliminated through calculation processing.
Compared with the prior art, the invention has the advantages that:
the invention only needs to measure the change of the input active power of the driving motor and the non-electrified load motor in a mechanical clutch or the driving motor running at the same rotation speed and under the empty load, does not need to change the input voltage of the tested motor at the same rotation speed to measure multiple measuring points and physical quantities, does not need to carry out a series of post-processing on the measured original experimental data, and has the advantages of small error introduced by the principle of the method, relatively simple measuring process and experimental data processing, high measuring efficiency and the like.
According to the invention, only two identical variable frequency motors are needed to be used as tested motors, any one of the motors can be used as a driving motor or a load motor, the driving motor is always connected with the coupler in the test process, the influence of wind friction loss of the coupler on a measurement result is eliminated, but the load motor is always in a non-energized state in the test process, and the mechanical loss of the driving motor is always loaded when the driving motor is connected with the non-energized load motor through the coupler or is coupled in series to carry out load operation test.
Drawings
FIG. 1 is a flow chart of a testing method according to an embodiment of the invention.
FIG. 2 is a schematic diagram of a testing device according to an embodiment of the present invention.
FIG. 3 is a diagram showing an embodiment of the test method of the present invention in a specific application.
Detailed Description
The invention is further described below with reference to the drawings and specific examples.
As shown in fig. 2, the dual clutch testing device for measuring the mechanical loss of the variable frequency motor in the embodiment of the invention comprises two variable frequency motors which are identical, a rotating speed measuring unit, a power measuring unit and a driving control unit, wherein one variable frequency motor is a driving motor, the other variable frequency motor is a load motor, and the driving motor is separated from or connected with the load motor through a coupler so as to realize the mechanical clutch of the driving motor and the load motor or the no-load or load of the driving motor; wherein the load motor is in a non-energized state; when the driving motor is connected with the load motor through the coupler, the rotating speed of the driving motor is measured through the rotating speed measuring unit, and the load input active power of the driving motor under the corresponding rotating speed is measured through the power measuring unit; when the driving motor is separated from the load motor through the coupler, the rotating speed of the driving motor is measured through the rotating speed measuring unit, and the idle input active power of the driving motor under the corresponding rotating speed is measured through the power measuring unit; the driving control unit is used for driving and controlling variable frequency speed regulation of the driving motor, so that the driving motor can randomly change the rotating speed within the speed regulation range for testing; the difference value of the load input active power and the idle input active power measured under the same rotating speed condition is the mechanical loss test result of the variable frequency or tested motor under the corresponding rotating speed.
In specific application, two identical variable frequency motors are selected as tested motors, any one of the motors can be used as a driving motor or a load motor, mechanical clutch of the two motors is realized through a coupler, no-load or load of the driving motor is realized in a form of either clutch or clutch, and no-load or load of the driving motor is always in a non-energized state. The mechanical loss of the motor under test is measured by measuring the variation in the input active power of the drive motor operating at any given speed, idle and loaded.
Wherein the input active power of the idle operation of the driving motor comprises copper loss, iron loss and mechanical loss components. The driving motor and the load motor are completely the same motor, the driving motor is connected with the non-energized load motor through a coupler or is coupled in series to carry out mechanical loss of the driving motor during load operation test, the mechanical loss is usually only a few percent of rated power of the tested motor, the load is small, and meanwhile, the change of the rotating speed, the mechanical loss, the current and the copper loss of the driving motor before and after loading is small due to the fact that the rotating speeds of the driving motor in no-load operation test and the load operation test are the same, the change can be approximately considered unchanged, but the iron loss is unchanged. Therefore, the invention loads the mechanical loss of the tested motor, and measures the separated mechanical loss of the tested motor.
As shown in fig. 2, the driving motor and the load motor are fixed on a cast iron flat plate with a T-shaped groove through bolt installation, and mechanical clutch of the driving motor and the load motor is realized through a coupler. When the coupler is only connected with the driving motor and is not connected with the load motor, the driving motor is separated or separated from the load motor, and the driving motor is in an idle state; when the driving motor is connected or coupled with the load motor through the coupler, the driving motor is in a load state. The input of the drive motor is connected to the output R, S, T of the inverter by a cable, while the input U, V, W of the inverter is connected to the output of the 50Hz three-phase sinusoidal ac power supply by a cable. The rated power, rated voltage, rated current, rated rotation speed and highest rotation speed of the driving motor should be matched with the frequency converter. The power measuring unit is used for measuring the change of the input active power of the driving motor operated at any given rotating speed and the idle load, and the rotating speed measuring unit is used for measuring the corresponding rotating speed.
Specifically, the power measurement unit is composed of a current sensor, a power measurement analyzer (integrating signal conditioning, acquisition, analysis and display functions) and a computer. The current sensor is used for measuring the input current of the driving motor. Three wires connecting the input end of the driving motor and the output end of the frequency converter pass through the center holes of the three current sensors respectively, as shown in fig. 2. The output signals of the three current sensors are respectively connected to the corresponding current input ends of the power measurement analyzer through signal transmission lines. The input voltage of the driving motor (the output voltage of the frequency converter) is directly connected to the corresponding voltage input end of the power measurement analyzer through three wires respectively.
The rotating speed measuring unit consists of a speed sensor, a signal conditioning box and a computer. The signals measured by the speed sensor are amplified and filtered by the signal conditioning box and then are collected by the collecting card of the signal conditioning box, and finally are directly led into a computer for analysis through a data transmission line. The voltage, current and power signals measured by the power measurement analyzer can also be led into a computer for analysis through a data transmission line.
The invention only needs to measure the change of the input active power of the driving motor and the non-electrified load motor in a mechanical clutch or the driving motor running at the same rotation speed and under the empty load, does not need to change the input voltage of the tested motor at the same rotation speed to measure multiple measuring points and physical quantities, does not need to carry out a series of post-processing on the measured original experimental data, and has the advantages of small error introduced by the principle of the method, relatively simple measuring process and experimental data processing, high measuring efficiency and the like.
According to the invention, only two identical variable frequency motors are needed to be used as tested motors, any one of the motors can be used as a driving motor or a load motor, the driving motor is always connected with the coupler in the test process, the influence of wind friction loss of the coupler on a measurement result is eliminated, but the load motor is always in a non-energized state in the test process, and the mechanical loss of the driving motor is always loaded when the driving motor is connected with the non-energized load motor through the coupler or is coupled in series to carry out load operation test.
As shown in fig. 1, the embodiment of the invention also discloses a testing method based on the dual clutch testing device for measuring the mechanical loss of the variable frequency motor, which comprises the following steps:
connecting a driving motor with a load motor through a coupler, and measuring the load input active power of the driving motor at different rotating speeds;
the method comprises the steps of separating a driving motor from a load motor through a coupler, and measuring idle load input active power of the driving motor at different rotating speeds;
the difference value of the load input active power and the idle input active power measured under the same rotating speed condition is the mechanical loss test result of the variable frequency motor at the corresponding rotating speed.
The same dual-machine mechanical clutch driving motor has the principle that the same-speed running loss is approximately unchanged, the mechanical loss of the tested motor is loaded, the separated mechanical loss of the tested motor is measured, and the accuracy of a measuring result can be ensured. The method has the advantages of innovation in principle, smaller introduced error and higher credibility of the measurement result. The existing idle constant-speed voltage transformation method measurement principle requires that the tested motor runs idle at the same rotating speed and simultaneously requires that the input voltage of the tested motor is changed to perform multi-measuring-point multi-physical-quantity measurement, the purpose is to obtain the idle input active power of the tested motor and a change curve of loss of copper loss with the input voltage, and obtain a test result of the mechanical loss of the tested motor by extending the two curves to obtain an intersection point, but the measurement principle of the method is not applicable to the mechanical loss measurement of the variable frequency motor with the unchanged input voltage once the rotating speed is given. The same dual-machine mechanical clutch driving motor of the invention has the following principle that the same-speed running loss is approximately unchanged: optionally, two identical variable frequency motors are used as tested motors, any one of the variable frequency motors can be used as a driving motor or a load motor, the driving motor is always connected with a coupler, the influence of wind friction loss of the coupler is eliminated, the load motor is always in a non-energized state, mechanical clutch is carried out on the two motors through the coupler to realize no-load or load of the driving motor, and the mechanical loss of the tested motor is measured by measuring the change of active power input by the driving motor running at the same rotating speed and no load.
The input active power to drive the motor idle (separate from the unpowered load motor) includes mechanical losses, core losses, and copper losses. The driving motor is connected or coupled in series with the load motor which is completely the same as the driving motor through a coupler, and drives the non-energized load motor to run together with the driving motor at the same idle rotation speed for loading, and the loading is the mechanical loss of the driving motor. The degree of influence of loading on the mechanical loss, iron loss and copper loss of the driving motor directly determines the measurement accuracy.
The influence of the loading on the rotation speed and the mechanical loss of the driving motor is small, and the driving motor can be approximately considered unchanged, because: 1. because the driving motor and the load motor are completely the same motors, the rotation speed of the driving motor in the idle load operation test is the same, the mechanical loss of the driving motor is loaded during the load test of the driving motor, the mechanical loss is usually only a few percent of the rated power of the driving motor, the load is smaller, and the influence on the rotation speed of the driving motor is almost avoided; 2. the variation in rotor rotational friction characteristics of identical motors is almost very small.
Wherein the loading has no effect on the iron loss of the driving motor, because: 1. because the measurement of the active power input before and after the loading of the driving motor is carried out at the same rotating speed, the power supply frequency of the inverter is kept the same, so that the alternating frequency of the magnetic field before and after the loading is not changed; 2. the magnetic flux or magnetic flux density is uniquely determined regardless of the load, regardless of the control speed regulation zone, once the drive motor speed or inverter power frequency is determined. The driving motor performs constant torque control speed regulation at rated rotation speed and below, magnetic flux is kept unchanged all the time, and performs constant power flux weakening control speed regulation at rated rotation speed and above, the magnetic flux is inversely proportional to the rotation speed, and once the rotation speed is determined, the magnetic flux is determined.
Although the input current before and after loading of the drive motor changes, the current and copper loss change due to the smaller applied load is also small and can be approximately considered unchanged. However, the influence of current and copper loss change before and after loading the driving motor can be eliminated by measuring three-phase input current of the driving motor running at the same rotation speed and empty or load and stator winding phase resistance during shutdown and then by the following calculation processing.
Specifically, the input active power measured before the driving motor is loaded is P 1， The three phases of input current are respectively I 11 、I 12 And I 13 The measured rotation speed is n 1 The method comprises the steps of carrying out a first treatment on the surface of the The input active power measured under the same rotating speed condition after the driving motor is loaded is P 2 The measured three-phase input currents are respectively I 21 、I 22 And I 23 The method comprises the steps of carrying out a first treatment on the surface of the The phase resistances of the stator windings measured when the driving motor is stopped are respectively R 1 、R 2 And R is 3 . The corrected mechanical loss measurement result isSimilarly, the mechanical loss measurement result of any measured rotational speed can be corrected.
The invention measures the mechanical loss of the tested motor by measuring the mechanical clutch of the driving motor and the non-electrified load motor or the change of the input active power of the driving motor in the same rotating speed and the idle load operation, does not need to change the input voltage of the tested motor at the same rotating speed to measure multiple measuring points and multiple physical quantities, does not need to carry out a series of post-processing on the measured original experimental data (including copper loss calculation of each measuring point, loss calculation for deducting copper loss and the test result of eliminating electromagnetic loss and separating out the mechanical loss by drawing and prolonging the acquisition of an intersection point), has relatively simple measuring process and high measuring efficiency.
In order to better understand the above technical solutions, the following detailed description will refer to the accompanying drawings and specific embodiments.
(1) Optionally, two identical variable frequency motors are used as tested motors, wherein any one of the motors can be used as a driving motor or a load motor (which is not electrified all the time), mechanical clutch of the two motors is realized through a coupler, no-load or load of the driving motor is realized in a form of either separation (the driving motor is separated from the non-electrified load motor through the coupler) or combination (the driving motor is connected with the non-electrified load motor through the coupler or is coupled in series), no-load or load is realized, the driving motor is always connected with the coupler, and the influence of wind friction loss of the coupler on a measurement result is eliminated.
(2) Setting driving motor parameters, control mode, starting frequency and speed raising mode.
2.1, the output end of the 50Hz three-phase sinusoidal alternating current power supply is connected to the power input end U, V and W of the inverter respectively by adopting a power cable, and the power output ends R, S and T of the inverter are connected to the input end of the stator winding of the driving motor respectively.
2.2 closing the inverter power switch S1 shown in fig. 2 to enable the inverter to be in an electrified state, and preparing for setting the parameters, control mode, starting frequency and speed increasing mode of the driving motor.
And 2.3, setting parameters of the driving motor through an inverter control panel. The parameters that the drive motor needs to set include the basic parameters (resistance, inductance, number of poles, type), the rated parameters (rated power, rated voltage, rated current, rated rotational speed) and the highest operating frequency of the drive motor. The method comprises the steps of finding a motor parameter setting module of inverter control software through a navigation key on an inverter control panel, displaying the found motor parameter setting module on a display screen of the control panel, finding a corresponding code of a motor parameter to be set through the navigation key on the control panel, confirming by pressing an Enter key, setting a parameter value of a driving motor through an increase and decrease key and a shift key on the control panel, and confirming by pressing the Enter key after setting.
And 2.4, setting a control mode of the driving motor through an inverter control panel. The control mode of the drive motor is set in a similar way as the motor parameter setting. The control modes adopted by the driving motor in the speed regulating area of the rated rotation speed and below and the speed regulating area of the rated rotation speed and above are different, and the driving motor should be set respectively. When setting, a constant torque control mode should be selected in the speed regulation area at the rated rotation speed and below, and a constant power weak magnetic control mode should be selected in the speed regulation area at the rated rotation speed and above.
And 2.5, setting the starting frequency and the speed increasing mode of the driving motor through an inverter control panel. The starting frequency and the rising speed of the driving motor are set by adopting a method similar to the setting of the motor parameters. In order to reduce system impact, reduce starting current and prevent the starting current from being overlarge, the inverter is automatically tripped due to overcurrent protection, so that starting failure is caused, meanwhile, enough starting torque is ensured during starting, and a driving motor adopts a voltage-dropping frequency-reducing soft starting mode instead of a direct starting mode (starting at rated voltage and rated frequency). Typically, the starting frequency of soft starts is relatively low (varying in magnitude from a few hertz, tens of hertz to tens of hertz), as well as the starting voltage is relatively low (much lower than the rated voltage 380V). The selection and setting of the magnitude of the soft start frequency should be determined according to the specific application of the motor under test. The requirements on the speed increasing modes are different according to the application occasions of the tested motors, and the specific speed increasing modes are selected according to the specific conditions. The common speed raising modes include straight line, broken line, S curve and parabola.
(3) And when the driving motor is separated from or separated from the non-energized load motor, the driving motor is idle at different rotation speeds to input the measurement of the active power and the corresponding rotation speed.
And 3.1, the non-energized load motor is not connected with or separated from the coupler, so that the driving motor is in an idle state.
And 3.2, carrying out no-load frequency-reduction and frequency-reduction soft start on the driving motor through the inverter, and increasing the rotating speed to the target measurement rotating speed by adjusting the power supply frequency of the inverter.
And 3.3, the driving motor is fully idle running at a target measurement rotating speed until the mechanical loss is stable, and the idle running input active power and the corresponding rotating speed of the driving motor are respectively measured by adopting a power meter and a speed sensor shown in fig. 2 after the mechanical loss is stable.
And 3.4, changing the target measurement rotating speed, and repeating the step 3.3, so that the test result of inputting active power and corresponding rotating speed by the driving motor in idle running at different rotating speeds can be obtained. The measurement results are shown in Table 1.
Table 1 measurement results of the active power and the corresponding rotational speed of the drive motor at different rotational speeds
| Measuring rotation speed n (r/min) | n 1 | n 2 | n 3 | … | n i |
| Measuring active power P no-load (W) | P no-load1 | P no-load2 | P no-load3 | … | P no-loadi |
In table 1: i is the number of stations, i= 1,2.3, …, n. In order to truly reflect the change rule of the mechanical loss of the tested motor along with the rotating speed, the number of the measuring points is selected according to the rated working rotating speed and the highest working rotating speed of the tested motor.
(4) The drive motor is connected or coupled in series with the unpowered load motor through a coupling and is operated at different rotational speeds to input active power and corresponding rotational speed measurements.
And 4.1, stopping the operation of the driving motor by pressing a Stop key on the control panel of the inverter after the no-load test of the driving motor is finished.
And 4.2, connecting or coupling the driving motor with a non-energized load motor in series through a coupler to enable the driving motor to be in a load state.
And 4.3, carrying out load voltage-reducing frequency-reducing soft start on the driving motor through the inverter, and enabling the rotating speed to rise to the target measurement rotating speed through adjusting the power supply frequency of the inverter.
4.4, the driving motor is fully loaded to run to the stable mechanical loss at the target measurement rotating speed, and the active power and the corresponding rotating speed are respectively measured by adopting a power meter and a speed sensor shown in fig. 2 after the mechanical loss is stable.
And 4.5, changing the target measurement rotating speed, and repeating the step 4.4, so that the test result of the driving motor for inputting the active power and the corresponding rotating speed by the load operation of different rotating speeds can be obtained. The measurement results are shown in Table 2.
Table 2 measurement results of the input active power and corresponding rotational speed of the drive motor operating at different rotational speed loads
| Measuring rotation speed n (r/min) | n 1 | n 2 | n 3 | … | n j |
| Measuring active power P load (W) | P load1 | P load2 | P load3 | … | P loadj |
In table 2: j is the number of stations, j= 1,2.3, …, n. No matter how the number of measurement points and the measurement data in tables 1 and 2 are changed, when i=j, there must be n i ＝n j And the method is established, so that the measurement of the input active power of the idle load operation of the driving motor is ensured to be carried out under the same rotating speed condition.
(5) The difference between the measured values of the input active power of the driving motor operated at the same rotation speed and the idle load is the test result of the mechanical loss of the corresponding rotation speed of the tested motor, and the detailed result is shown in table 3. And an experimental curve or a mechanical loss experimental curve of the mechanical loss of the tested motor along with the change of the rotating speed can be generated through the measurement result of each rotating speed.
TABLE 3 mechanical loss test results for the tested motors
As used in this disclosure and in the claims, the terms "a," "an," "the," and/or "the" are not specific to a singular, but may include a plurality, unless the context clearly dictates otherwise. The terms "first," "second," and the like, as used in this disclosure, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Likewise, the word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above examples, and all technical solutions belonging to the concept of the present invention belong to the protection scope of the present invention. It should be noted that modifications and adaptations to the invention without departing from the principles thereof are intended to be within the scope of the invention as set forth in the following claims.
Claims (9)
1. The double-machine clutch type testing device for measuring the mechanical loss of the variable frequency motor is characterized by comprising two identical variable frequency motors, a rotating speed measuring unit, a power measuring unit and a driving control unit, wherein one variable frequency motor is a driving motor, the other variable frequency motor is a load motor, and the driving motor is separated from or connected with the load motor through a coupler so as to realize mechanical clutch of the driving motor and the load motor or empty load of the driving motor; wherein the load motor is always in a non-energized state;
when the driving motor is connected with the load motor through a coupler, the rotating speed of the driving motor is measured through the rotating speed measuring unit, and the load input active power of the driving motor under the corresponding rotating speed is measured through the power measuring unit;
when the driving motor is separated from the load motor through a coupler, the rotating speed of the driving motor is measured through the rotating speed measuring unit, and the idle input active power of the driving motor under the corresponding rotating speed is measured through the power measuring unit;
the driving control unit is connected with the driving motor and is used for driving the driving motor and controlling variable frequency speed regulation, so that the driving motor can randomly change the rotating speed within the speed regulation range to test;
the driving control unit is respectively connected with the rotating speed measuring unit and the power measuring unit and is used for obtaining the mechanical loss of the variable frequency motor according to the active power input by the load and the active power input by the idle load.
2. The dual clutch type testing device for measuring mechanical loss of variable frequency motor according to claim 1, wherein the driving motor is always connected with the coupler during the testing process so as to eliminate the influence of wind friction loss of the coupler on the measurement result.
3. The dual clutch type testing device for measuring mechanical loss of a variable frequency motor according to claim 1 or 2, wherein the rotation speed measuring unit comprises a speed sensor for measuring a rotation speed signal of the driving motor and a signal conditioning box for amplifying and filtering the rotation speed signal.
4. The dual clutch type test device for measuring mechanical loss of a variable frequency motor according to claim 1 or 2, wherein the power measuring unit comprises a current sensor for measuring input current of the driving motor, a voltage sensor and a power measuring analyzer; the voltage sensor is used for measuring the input voltage of the driving motor, and the power measurement analyzer is respectively connected with the current sensor and the voltage sensor and used for obtaining the input active power of the driving motor according to the measured input voltage, input current and power factor of the driving motor.
5. A testing method based on the dual clutch type testing device for measuring the mechanical loss of the variable frequency motor according to any one of claims 1 to 4, comprising the steps of:
the driving motor is connected with the load motor through a coupler, and the load input active power of the driving motor running at different rotating speeds under the load is measured;
the driving motor is separated from the load motor through a coupler, and idle input active power of the driving motor at different rotation speeds is measured;
and the difference value of the active power input by the load and the active power input by the idle load, which are measured under the same rotating speed condition, is the mechanical loss test result of the driving motor at the corresponding rotating speed.
6. The method according to claim 5, wherein the specific process of measuring the load input active power is:
the driving motor is connected or coupled in series with the non-energized load motor through a coupler, so that the driving motor is in a load state;
the driving motor carries out load voltage-dropping frequency-reducing soft start through the inverter, and the rotating speed of the driving motor is increased to the target measuring rotating speed by adjusting the power supply frequency of the inverter;
the driving motor fully loads and operates to the stable mechanical loss at the target measurement rotating speed, and after the mechanical loss is stable, the rotating speed of the driving motor load operation and the corresponding load input active power are respectively measured through the rotating speed measuring unit and the power measuring unit; changing the target measurement rotating speed, and repeating the steps to obtain the load input active power at different rotating speeds.
7. The test method according to claim 5, wherein the specific process of measuring the no-load input active power is:
the non-energized load motor is not connected with or separated from the coupler so as to enable the driving motor to be in an idle state;
the driving motor carries out no-load voltage-reducing frequency-reducing soft start through the inverter, and the rotating speed of the driving motor is increased to the target measuring rotating speed by adjusting the power supply frequency of the inverter;
the driving motor is fully idle running to stable mechanical loss at a target measurement rotating speed, and the idle running rotating speed of the driving motor and corresponding idle input active power are respectively measured through a rotating speed measuring unit and a power measuring unit after the mechanical loss is stable; changing the target measurement rotating speed, and repeating the steps to obtain the idle input active power at different rotating speeds.
8. The method according to claim 5, 6 or 7, wherein during the test, the drive motor selects a constant torque control mode in a speed regulation region at or below a rated rotational speed, and selects a constant power field weakening control mode in a speed regulation region at or above the rated rotational speed.
9. The test method according to claim 5, 6 or 7, wherein the influence of current and copper loss change before and after loading of the drive motor is eliminated by measuring three-phase input current and stator winding phase resistance at the time of shutdown of the drive motor at the same rotational speed and empty or loaded.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116699401A (en) * | 2023-07-27 | 2023-09-05 | 山西电机制造有限公司 | Comparison verification test method for separating iron loss and mechanical loss of ultra-efficient motor |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116699401A (en) * | 2023-07-27 | 2023-09-05 | 山西电机制造有限公司 | Comparison verification test method for separating iron loss and mechanical loss of ultra-efficient motor |
| CN116699401B (en) * | 2023-07-27 | 2023-10-27 | 山西电机制造有限公司 | Comparison verification test method for separating iron loss and mechanical loss of ultra-efficient motor |
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