阅读说明：本技术 一种电机损耗的测试装置 (Testing arrangement of motor loss ) 是由 吴涛 于 2020-12-29 设计创作，主要内容包括：本发明提供了一种电机损耗的测试装置,利用V/F控制模式产生电压指令,该电压指令经过SVPWM调制器产生三相逆变桥上功率器件的PWM驱动控制信号,定子绕组的电流可经过电流传感器采样后经过Park变换得到定子电流的有功电流和无功电流分量。同时为了更加精确的补偿由于定子电流存在谐波分量后的角度偏移,可在结构中增加由上述两个电压指令生成的角度补偿指令。经过待测的电机不需要拖动电机的台架下就可以产生足够的定子电流进行电机的热测试。待测的电机在V/F控制模式下,避免无功电流增大后引起的控制震荡。由于利用本发明的装置进行电机的测试,不需要电机转台的参与,因此上述电机热测试方法可以有效节能。(The invention provides a motor loss testing device, which utilizes a V/F control mode to generate a voltage instruction, the voltage instruction generates a PWM (pulse-width modulation) driving control signal of a power device on a three-phase inverter bridge through an SVPWM (space vector pulse-width modulation) modulator, and the current of a stator winding can be sampled by a current sensor and then subjected to Park conversion to obtain the active current and reactive current components of the stator current. Meanwhile, in order to more accurately compensate the angle offset caused by harmonic components of the stator current, the angle compensation command generated by the two voltage commands can be added into the structure. The motor to be tested can generate enough stator current to carry out the thermal test of the motor without dragging a rack of the motor. And the motor to be tested avoids control oscillation caused by the increase of reactive current in a V/F control mode. The device of the invention is used for testing the motor, and the participation of a motor rotary table is not needed, so the motor thermal testing method can effectively save energy.)

1. The testing device for the motor loss is characterized by comprising a control unit, a modulator, a conversion unit, an integration unit, an adjustment unit, a first calculation unit and a compensation unit;

the input end of the control unit is connected with an input power supply, the input power supply is used for providing a first voltage instruction to the control unit, the output end of the control unit is connected with the input end of the modulator, the input power supply is also connected with the integrating unit and is used for generating an angle compensation instruction, and the angle compensation instruction is fed back to the modulator;

the output end of the modulator is used for being connected with a motor and the input end of the conversion unit, the output end of the conversion unit and the output end of the compensation unit are connected to the input end of the regulation unit after passing through the first calculation unit, the output end of the regulation unit is connected with the input end of the modulator and the input end of the control unit, and the compensation unit is used for providing compensation current to the first calculation unit;

the adjusting unit is used for generating a second voltage instruction according to an output result of the first calculating unit and outputting the second voltage instruction to the control unit and the modulator, the control unit is used for generating a third voltage instruction according to the first voltage instruction and the second voltage instruction and supplying the third voltage instruction to the modulator, and the modulator is used for generating a load voltage according to the second voltage instruction and the third voltage instruction and supplying the load voltage to the motor.

2. The apparatus for testing loss of an electric motor according to claim 1, further comprising a function calculating unit;

the output end of the control unit and the output end of the adjusting unit are connected with the input end of the function calculating unit, the output end of the function calculating unit and the output end of the integrating unit are connected with the input end of a second calculating unit, and the output end of the second calculating unit is connected with the modulator and the transforming unit.

3. The apparatus for testing loss of an electric motor according to claim 2, wherein said function calculating unit is an arctangent function calculating unit.

4. The motor loss testing apparatus of claim 1, wherein the control unit comprises a V/F control module and a formula calculation module;

the input end of the V/F control module is connected with the input power supply, the output end of the V/F control module and the output end of the adjusting unit are connected to the input end of the formula calculation module, the output end of the formula calculation module is connected with the input end of the modulator, and the formula calculation module is used for generating the first voltage instruction.

5. The apparatus for testing motor loss according to claim 4, wherein the frequency of the input power is f, the rated voltage of the motor is Ve, the rated frequency of the motor is fe, the first voltage command is Vx, the second voltage command is Vy, and the formula of the first voltage command is:

if:then:if:then:

6. the apparatus for testing motor losses of claim 1, wherein said modulator is an SVPWM modulator.

7. The apparatus for testing motor loss according to claim 1, wherein a current sensor is further connected between the output terminal of the modulator and the input terminal of the transforming unit for sampling the current at the output terminal of the modulator.

8. The apparatus for testing motor loss according to claim 7, wherein the transformation unit is a Park transformation unit for performing Park transformation on the current sampled by the current sensor.

9. The apparatus for testing motor loss according to claim 1, wherein the regulating unit is a PI regulator for generating the second voltage command.

10. The apparatus for testing motor losses of claim 1, wherein the magnitude of the compensation current is set according to mechanical losses and stator losses of the motor.

Technical Field

The invention belongs to the technical field of electric energy regulation and control, and particularly relates to a testing device for motor loss.

Background

The loss test of the stator and the rotor of the alternating current motor is the basic requirement of the calibration of the motor driving equipment rack. In the traditional method, resistance torque is generated on the towed motor, so that enough stator current generated by motor driving equipment is ensured to enable the calorific value of the motor to cover the design torque range of the motor, but the towed motor rack is required to exist in the method to complete the task. The loss test of the tested motor is carried out on the towing motor rack, and the extra electric energy loss of the load motor and the load frequency converter can be caused inevitably. Usually, loss tests of the motor are calibrated under different motor rotating speeds and load torques, so that the traditional motor loss test method needs to pay extra equipment cost and electricity charge.

In the conventional motor loss test methods, a loss test method without load motor loss is also adopted, and a large stator current needs to be generated in a stator winding of the motor. In order to achieve the above effect, a rotation speed control signal slightly deviating from the reference rotation speed test is generally superimposed on the reference rotation speed at some rotation speed test points of the motor. For example, the required rated voltage command of the motor is controlled at 60Hz, and a voltage command of 40 or 50Hz is superimposed on the rated voltage command when the command is actually generated. Under the above conditions, the stator winding of the motor can be excited to a magnitude up to the rated current even if the motor operates without load. However, the above control method has problems that: because the tested motor is in an open-loop working mode, the motor can work in an unstable area before the motor rises to a rated rotating speed due to singular characteristic values of motor parameters, and the risk of oscillation and even out of control of the rotating speed of the motor is caused.

Disclosure of Invention

The invention aims to provide a motor loss testing device which is used for solving the problems that in the prior art, because a tested motor is in an open-loop working mode, the motor can work in an unstable area before the motor rises to a rated rotating speed due to singular characteristic values of motor parameters, so that the rotating speed control of the motor has the risk of oscillation and even out of control and the like.

In order to solve the above technical problem, the present invention provides a testing apparatus for motor loss, which includes a control unit, a modulator, a transformation unit, an integration unit, an adjustment unit, a first calculation unit, and a compensation unit;

the input end of the control unit is connected with an input power supply, the input power supply is used for providing a first voltage instruction to the control unit, the output end of the control unit is connected with the input end of the modulator, the input power supply is also connected with the integrating unit and is used for generating an angle compensation instruction, and the angle compensation instruction is fed back to the modulator;

the output end of the modulator is used for being connected with a motor and the input end of the conversion unit, the output end of the conversion unit and the output end of the compensation unit are connected to the input end of the regulation unit after passing through the first calculation unit, the output end of the regulation unit is connected with the input end of the modulator and the input end of the control unit, and the compensation unit is used for providing compensation current to the first calculation unit;

the adjusting unit is used for generating a second voltage instruction according to an output result of the first calculating unit and outputting the second voltage instruction to the control unit and the modulator, the control unit is used for generating a third voltage instruction according to the first voltage instruction and the second voltage instruction and supplying the third voltage instruction to the modulator, and the modulator is used for generating a load voltage according to the second voltage instruction and the third voltage instruction and supplying the load voltage to the motor.

Furthermore, the system also comprises a function calculation unit;

the output end of the control unit and the output end of the adjusting unit are connected with the input end of the function calculating unit, the output end of the function calculating unit and the output end of the integrating unit are connected with the input end of a second calculating unit, and the output end of the second calculating unit is connected with the modulator and the transforming unit.

Optionally, the function calculating unit is an arc tangent function calculating unit.

Optionally, the control unit includes a V/F control module and a formula calculation module;

the input end of the V/F control module is connected with the input power supply, the output end of the V/F control module and the output end of the adjusting unit are connected to the input end of the formula calculation module, the output end of the formula calculation module is connected with the input end of the modulator, and the formula calculation module is used for generating the first voltage instruction.

Optionally, the frequency of the input power supply is f, the rated voltage of the motor is Ve, the rated frequency of the motor is fe, the first voltage command is Vx, the second voltage command is Vy, and the formula of the first voltage command is:

if:then:if:then:

optionally, the modulator is an SVPWM modulator.

Optionally, a current sensor is further connected between the output end of the modulator and the input end of the transformation unit, and is used for sampling a current at the output end of the modulator.

Optionally, the conversion unit is a Park conversion unit, and is configured to perform Park conversion on the current sampled by the current sensor.

Optionally, the adjusting unit is a PI regulator for generating a second voltage command.

Optionally, the magnitude of the compensation current is set according to mechanical losses and stator losses of the motor.

The invention provides a motor loss testing device, which utilizes a V/F control mode to generate a voltage instruction, the voltage instruction generates a PWM driving control signal of a power device on a three-phase inverter bridge through an SVPWM modulator, and the current of a stator winding can be sampled by a current sensor and then is subjected to Park conversion to obtain the active current and reactive current components of the stator current. Because the motor to be measured works in a no-load mode, a compensation current is required to be externally arranged for compensating the inherent mechanical loss of the motor rotation friction and the stator loss of the motor. The active current passes through a voltage command output by the PI regulator and the previous voltage command and generates PWM driving signals of six power switching tubes of the three-phase inverter through the SVPWM modulator. Meanwhile, in order to more accurately compensate the angle offset caused by harmonic components of the stator current, the angle compensation command generated by the two voltage commands can be added into the structure. The motor to be tested can generate enough stator current to carry out the thermal test of the motor without dragging a rack of the motor. And the motor to be tested avoids control oscillation caused by the increase of reactive current in a V/F control mode. Because the motor is tested without the participation of a motor rotary table, the motor thermal testing method can effectively save energy.

Drawings

Fig. 1 is a schematic structural diagram of a device for testing motor loss according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of another testing apparatus for testing motor loss according to an embodiment of the present invention;

10-a control unit, 101-a V/F control module, 102-a formula calculation module, 11-a modulator, 12-a transformation unit, 13-an integration unit, 14-an adjustment unit, 15-a compensation unit, 16-an input power supply, 17-a first calculation unit, 18-a function calculation unit, 19-a second calculation unit and 20-a motor.

Detailed Description

The following describes a testing apparatus for motor loss according to the present invention in further detail with reference to the accompanying drawings and specific embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "left", "right", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

As shown in fig. 1, an embodiment of the present invention provides a device for testing motor loss, which includes a control unit 10, a modulator 11, a transformation unit 12, an integration unit 13, an adjustment unit 14, a first calculation unit 17, and a compensation unit 15. An input end of the control unit 10 is connected to an input power supply 16, the input power supply is configured to provide a first voltage command to the control unit 10, and an output end of the control unit 10 is connected to an input end of the modulator 11. The input power supply 16 is further connected to the integrating unit 13 for generating an angle compensation command, and the angle compensation command is fed back to the modulator 11.

The output end of the modulator 11 is connected to a motor 20 and the input end of the transforming unit 12, and the output end of the transforming unit 12 and the output end of the compensating unit 15 are connected to the input end of the adjusting unit 14 after passing through the first calculating unit 17. The output end of the adjusting unit 14 is connected to the input end of the modulator 11 and the input end of the control unit 10, the compensating unit 15 is configured to provide a compensating current to the first calculating unit 17, the adjusting unit 14 generates a second voltage command according to the output result of the first calculating unit 17 and outputs the second voltage command to the control unit 10 and the modulator, the control unit 10 is configured to generate a third voltage command according to the first voltage command and the second voltage command and provide the third voltage command to the modulator 11, and the modulator 11 is configured to generate a load voltage according to the second voltage command and the third voltage command and provide the load voltage to the motor 20.

And generating the third voltage command by using the control unit 10, wherein the voltage command generates a driving control signal of a power device on the three-phase inverter bridge through the modulator 11, and the current of the stator winding passes through the transformation unit 12 to obtain active current and reactive current components of the stator current. Since the motor 20 to be measured is operated in the no-load mode, a compensation unit 15 is required to provide a compensation current, wherein the magnitude of the compensation current is selected according to the inherent mechanical loss of the rotational friction of the motor 20 and the stator loss of the motor 20. The active current generates the driving signals of six power switching tubes of the three-phase inverter through the modulator 11 through the voltage command output by the regulating unit 14 and the previous voltage command. The structure provided by the embodiment can effectively avoid the control increase caused by overlarge reactive current, so that the tested motor 20 can meet the requirement of the current effective value of the thermal test of the motor 20 under the condition of no load motor. In addition, the motor rotary table is not needed, so that the device provided by the invention can effectively save energy.

Further, in order to more accurately compensate for the angular offset of the harmonic components due to the stator currents, the device may be provided with a function calculation unit 18. As shown in fig. 2, the output of the control unit 10 and the output of the adjusting unit 14 are connected to the input of the function calculating unit 18, the output of the function calculating unit 18 and the output of the integrating unit 13 are connected to the input of a second calculating unit 19, and the output of the second calculating unit 19 is connected to the modulator 11 and the transforming unit 12.

Optionally, the function calculation unit 18 is an arctangent function calculation unit 18.

Optionally, the control unit 10 includes a V/F control module 101 and a formula calculation module 102. The input end of the V/F control module 101 is connected to the input power supply 16, the output end of the V/F control module 101 and the output end of the regulating unit 14 are connected to the input end of the formula calculation module 102, the output end of the formula calculation module 102 is connected to the input end of the modulator 11, and the formula calculation module 102 is configured to generate the first voltage command.

Optionally, the frequency of the input power source 16 is f, the rated voltage of the motor 20 is Ve, the rated frequency of the motor 20 is fe, the first voltage command is Vx, the second voltage command is Vy, and the formula of the first voltage command is:

when in useWhen the first voltage command Vx is:when in useThen, the value of the first voltage forest Vx is:

therefore, the arctangent function unit actually obtains the arctangent function, namely arctan (Vy/Vx) of the first voltage command and the second voltage command, and obtains an angle command.

Alternatively, the modulator 11 may be configured as an SVPWM modulator 11, and of course, the SVPWM modulator 11 is not limited to be used, and may also be a general PWM modulator 11, and the present invention is not limited thereto, as long as the PWM signal required by the test can be obtained.

Optionally, a current sensor is further connected between the output end of the modulator 11 and the input end of the transformation unit 12 for sampling a current at the output end of the modulator 11.

Optionally, the transformation unit 12 is a Park transformation unit 12, configured to perform Park transformation on the current sampled by the current sensor. The current sampled by the current sensor comes from the current used to drive the motor 20 after the modulator 11.

Optionally, the adjusting unit 14 is a PI regulator for generating the second voltage instruction.

In summary, the testing apparatus for motor loss provided by the present invention utilizes a V/F control mode to generate a voltage command, the voltage command generates a PWM driving control signal of a power device on a three-phase inverter bridge through a SVPWM modulator, and the current of a stator winding can be sampled by a current sensor and then undergo Park conversion to obtain active current and reactive current components of the stator current. Because the motor to be measured works in a no-load mode, a compensation current is required to be externally arranged for compensating the inherent mechanical loss of the motor rotation friction and the stator loss of the motor. The active current passes through a voltage command output by the PI regulator and the previous voltage command and generates PWM driving signals of six power switching tubes of the three-phase inverter through the SVPWM modulator. Meanwhile, in order to more accurately compensate the angle offset caused by harmonic components of the stator current, the angle compensation command generated by the two voltage commands can be added into the structure. The motor to be tested can generate enough stator current to carry out the thermal test of the motor without dragging a rack of the motor. And the motor to be tested avoids control oscillation caused by the increase of reactive current in a V/F control mode. Because the motor is tested without the participation of a motor rotary table, the motor thermal testing method can effectively save energy.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example" or "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. And the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments. Furthermore, various embodiments or examples described in this specification can be combined and combined by those skilled in the art.

Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.