CN217332661U - Aging loading device of frequency converter - Google Patents

Abstract

The application provides a converter loading device that ages includes: the input ends of the plurality of test branches are used for receiving the output current of the frequency converter to be tested, and the plurality of test branches are provided with load loading devices; the input end of the energy recovery unit is connected with the output ends of the plurality of test branches, and the output end of the energy recovery unit is connected with the frequency converter to be tested and used for recovering and feeding back the output currents of the plurality of test branches to the frequency converter to be tested; and the control unit is connected with the plurality of test branches and used for controlling the on-off of the plurality of test branches according to the power section of the frequency converter to be tested so as to provide an aging test load matched with the power section of the frequency converter to be tested.

Description

Aging loading device of frequency converter

Technical Field

The application relates to the field of frequency converter testing, in particular to an aging loading device for a frequency converter.

Background

The aging test is an important ring in the reliability test of the frequency converter, and comprises the step of testing the requirements of the frequency converter such as overvoltage, short circuit, rated load, overload and the like so as to comprehensively detect the functions and the reliability of a control loop and a driving loop of a frequency converter product.

In the related art, a flywheel or a motor torsion mode is generally adopted for aging loading test. The method can only realize the test of the frequency converter within a narrow power range, and has complex structure and low test efficiency.

SUMMERY OF THE UTILITY MODEL

In view of this, an embodiment of the present application provides an apparatus for loading aging of a frequency converter, where the apparatus includes: the input ends of the plurality of test branches are used for receiving the output current of the frequency converter to be tested, and the plurality of test branches are provided with load loading devices; the input end of the energy recovery unit is connected with the output ends of the plurality of test branches, and the output end of the energy recovery unit is connected with the frequency converter to be tested and used for recovering and feeding back the output currents of the plurality of test branches to the frequency converter to be tested; and the control unit is connected with the plurality of test branches and used for controlling the on-off of the plurality of test branches according to the power section of the frequency converter to be tested so as to provide an aging test load matched with the power section of the frequency converter to be tested.

Optionally, contactors are arranged on the plurality of test branches, and the contactors are connected with the control unit and used for being switched on and off under the control of the control unit according to the power section of the frequency converter to be tested.

Optionally, the load loading device includes a reactor and a rectifier connected in series, and an output end of the rectifier is connected to the energy recovery unit, and is configured to invert an output current of the reactor into a dc signal and output the dc signal to the energy recovery unit.

Optionally, the rectifier is connected to the control unit, so that the control unit can adjust a current parameter of the rectifier according to the power section of the frequency converter to be tested, so as to adjust a load on the test branch.

Optionally, the energy recovery unit includes an inverter for inverting the dc signal output by the rectifier into an ac signal with the same frequency and phase as the ac signal provided by the energy recovery unit.

Optionally, the energy recovery unit further includes an inductor-capacitor-inductor filter, and the inductor-capacitor-inductor filter is disposed between the inverter and the frequency converter to be tested, and is configured to filter out harmonics in an output signal of the inverter.

Optionally, the test branches further include a filtering unit, and the filtering unit is disposed between the frequency converter to be tested and the load loading device, and is configured to filter out harmonics in an output signal of the frequency converter to be tested.

Optionally, the filtering unit includes an inductor-capacitor filter, and is configured to filter out a harmonic in an output signal of the frequency converter to be tested.

Optionally, the filtering unit further includes an isolation transformer, and the isolation transformer is disposed between the inductor-capacitor filter and the load loading device, and is configured to electrically isolate the test branch and filter out odd harmonics generated by the frequency converter to be tested.

Optionally, the frequency converter aging loading device further includes a power segment obtaining unit, where the power segment obtaining unit is connected to the control unit, and is configured to obtain and send the power segment of the frequency converter to be tested to the control unit. The frequency converter aging loading device provided by the embodiment of the application controls the on-off of each test branch according to the power section of the frequency converter to be tested by arranging a plurality of load loading devices which are connected in parallel, so that the aging test of the frequency converter within a wider power range can be realized, the test efficiency is improved, and the energy consumption of the loading devices is reduced.

Drawings

Fig. 1 is a schematic structural diagram of an aging loading device of a frequency converter according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of an aging loading apparatus of a frequency converter according to another embodiment of the present application;

Detailed Description

For the convenience of understanding, before describing the embodiments of the present application, a method for testing the aging of a frequency converter in the prior art and the problems thereof will be described in detail.

A manufacturer of a frequency converter needs to test various performances of the frequency converter before the product is delivered from a factory. The aging test is an important loop in the reliability test of the frequency converter, and comprises the step of testing the requirements of the frequency converter such as overvoltage, short circuit, rated load, overload and the like so as to comprehensively detect the functions and the reliability of a control loop and a driving loop of a frequency converter product.

There are various methods for burn-in test of frequency converters in the related art. For example, the output end of the frequency converter to be tested can be connected with an asynchronous motor, a flywheel assembly with large mass is arranged on the output shaft of the asynchronous motor to serve as a load, the frequency converter to be tested is used for driving the motor to rotate, and then the flywheel assembly is driven to rotate, so that the frequency converter to be tested is loaded.

Alternatively, in some related arts, the torque may be also be applied by a motor. Specifically, for example, a load motor and a loading motor are mechanically coupled through a coupler and the like, the frequency converter to be tested is used for driving the load motor to rotate, the load motor drives the loading motor to rotate under the action of the coupler, and the loading motor drives a four-quadrant frequency converter of the loading motor to feed energy back to a power supply system.

In the test mode of using the flywheel subassembly as load, the current value that uses after steady operation is less, the unable abundant problem that exposes the converter existence to in the test procedure, most energy all converts the kinetic energy of flywheel rotation and loses. The burn-in test usually lasts for a long time, and the loss of energy causes the test cost to increase.

In the technical scheme of motor torque-to-torque, instantaneous current of a load motor and an on-load motor is large when the load motor and the on-load motor are started, and high requirements are provided for the performance of a power supply system. On the other hand, although the test method can recover energy to a certain degree, a large part of the energy is converted into heat energy to be volatilized, so that the energy recovery efficiency is low. In addition, the mechanical connection methods such as the coupling can generate large noise during testing.

With the development of test technology, a burn-in test method using a reactor as a load appears in the related art. The output end of the frequency converter to be tested is connected with the reactor in series, the output end of the reactor is connected with the bus of the power supply system in parallel, and energy is fed back to the input end of the frequency converter to be tested.

However, when the aging test system based on the reactor is designed, the type of the reactor is usually matched with the power of the frequency converter to be tested to which the test system is applied. In other words, such a test system in the related art can perform only a test of a frequency converter of a narrow frequency band. When the frequency converters with different power sections need to be tested, different reactors are often required to be replaced, which results in complex operation and low efficiency of the testing process.

In view of the above problems, embodiments of the present application provide an aging loading device for frequency converters, which utilizes a plurality of load loading devices connected in parallel to realize batch testing of frequency converters in different power sections, and solves the testing requirement in a wider power range; and meanwhile, the energy recovery unit is utilized to recover the energy of the aging loading device of the frequency converter, so that the energy consumption is further reduced.

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Fig. 1 is a schematic structural diagram of an aging loading apparatus 10 for a frequency converter provided in an embodiment of the present application, where the aging loading apparatus for a frequency converter in fig. 1 includes: a load loading device 11, an energy recovery unit 12 and a control unit 13.

The output end of the frequency converter to be tested is connected to a plurality of test branches (for example, three test branches are shown in fig. 1), wherein each test branch is provided with a load loading device 11. In other words, a plurality of load loading devices 11 are connected in parallel, wherein an input end of each load loading device 11 is connected with an output end of the frequency converter to be tested. In the frequency converter aging loading device 10, the load loading device 11 is used as a load to realize the aging test of the frequency converter to be tested.

In some embodiments, in order to solve the test requirement of a wider power range, the loading device is suitable for loading of frequency converters to be tested in different power sections. The load loading devices 11 on the plurality of test branches may be configured to be switchably connected to the output end of the frequency converter to be tested. The load of the loading device can be adjusted by controlling the on-off of each test branch. For example, when the power section of the frequency converter to be tested is 45-55kW, two of the multiple test branches can be controlled to be closed, so that the other test branches are all opened, and the test on the frequency converter of the frequency section can be completed by using the load loading devices on the two test branches in the closed state; and when the power section of the frequency converter to be tested is 90-132kW, the three testing branches can be controlled to be closed simultaneously, and the test of the power section can be met.

With continued reference to fig. 1, the loading device provided in the embodiment of the present application further includes an energy recovery unit 12. The energy recovery unit 12 is arranged on a trunk of the loading device, an input end of the energy recovery unit 12 is connected with output ends of the load loading devices 11 on the plurality of test branches, current output by the frequency converter to be tested can be converged into the energy recovery unit 12 after flowing through the plurality of load loading devices 11 connected in parallel, the energy recovery unit 12 rectifies and regulates the current, and then alternating current signals with the same frequency and phase provided by the power supply unit are input into the frequency converter to be tested again together, so that the whole frequency converter aging loading device only generates a small part of energy loss in a control loop and an energy conversion process of the frequency converter to be tested, most of energy is still fed back into the loading device in an electric energy mode, and the energy consumption of the system is reduced.

And the control unit 13 is used for executing the control of the frequency converter aging loading device 10. The control unit 13 may be connected to the frequency converter under test and the energy recovery unit 12. When the loading device is used for carrying out aging loading on the frequency converter to be tested, the control unit 13 can obtain the power section of the frequency converter to be tested, determine the required load reactance value according to the power section of the frequency converter to be tested, and further realize aging loading test on the frequency converters with different power sections by controlling the on-off of each test branch.

The loading device provided by the embodiment of the application controls the on-off of each test branch according to the power section of the frequency converter to be tested by arranging the plurality of load loading devices which are connected in parallel, so that the test system can test the frequency converter within a wider power range, the test efficiency can be improved, and the energy consumption of the loading device is reduced.

In some embodiments, the loading device may further include a power supply unit 14, where the power supply unit 14 is configured to be connected to an input end of the frequency converter under test, and is used to provide power to the frequency converter under test. The power supply unit may be, for example, an ac power grid, for example, capable of supplying a three-phase ac power with a rated voltage of 380V to the frequency converter under test.

In some embodiments, the loading device provided in the embodiments of the present application may be disposed in an automatic test system of a frequency converter. At this time, the connection between the output end of the power supply unit and the input end of the frequency converter to be tested may be: when the frequency converter to be tested is moved to a test station of an automatic test system by an automatic assembly line or an unmanned guide vehicle, the input end of the frequency converter to be tested is butted with a power supply terminal of the test system, and a power supply unit can supply power to the frequency converter to be tested through the butted terminals.

In some embodiments, the connection between the load loading devices 11 on the multiple test branches and the output end of the frequency converter under test may also be implemented by corresponding terminal terminals in the automatic test system, which is similar to the connection between the aforementioned power supply unit and the input end of the frequency converter under test, and will not be further described herein.

In some embodiments, the plurality of load loading devices 11 in the testing device 10 may provide the same or different burn-in test loads, which is not limited in this embodiment of the present invention. For example, the sizes of the loads provided by the multiple load loading devices 11 may be set to be different, and when the power of the frequency converter to be tested is small, one corresponding test branch may be selected according to the power of the frequency converter to work, so as to reduce the influence on the energy recovery unit 12 and the control unit 13 due to the need of the multiple test branches to work cooperatively; when the frequency converter is used for executing aging loading of a frequency converter with higher power, a plurality of test branches can be controlled to work simultaneously, and energy loss can be reduced by reasonably configuring the size of the load provided by the plurality of load loading devices 11.

Fig. 2 shows a schematic structural diagram of a loading device according to another embodiment of the present application. Referring to fig. 2, in some embodiments, the loading device further includes a plurality of contactors 21, and the contactor 21 may be disposed in front of the load loading device 11 in each test branch to connect the frequency converter under test with the load loading device 11, so as to implement the above-mentioned switchable connection between the load loading device 11 on each test branch and the output end of the frequency converter under test.

The contactor 21 may be connected to the control unit 13. In some embodiments, the control unit 13 may include a Programmable Logic Controller (PLC), and the coil of the contactor 21 is connected to a digital output interface of the PLC, and the PLC may output a high/low level to control the power on/off of the coil of the contactor 21, so as to control the on/off of each test branch.

In some embodiments, as shown in fig. 2, the load loading device 11 may include a reactor 111 therein for providing an aging test load for the frequency converter under test. Therefore, the loading by the load loading devices 11 on the plurality of test branches may be performed by the reactors 111 on the plurality of test branches. It can be understood that the outputs of the reactors 111 in the multiple test branches are all ac signals, and when the parameters of the reactors 111 in the test branches are different, the frequency and/or phase of the current signals output by the test branches may have a large difference. It will also be appreciated that if the ac signals with different amplitudes and/or phases are simply superimposed and fed back to the frequency converter under test, this may cause disturbances in the input signal of the frequency converter and even irreversible losses such as short circuits.

In view of the above, in some embodiments, with continuing reference to fig. 2, a rectifier 112 may be disposed in the load loading device 11 on each test branch. The rectifier 112 may be disposed behind the reactor 111, and an input end thereof is connected to an output end of the reactor 111, and is capable of receiving an ac signal output by the reactor 111 and inverting the ac signal into a dc signal.

The output signal of the rectifier 112 of each test branch can be transmitted to the energy recovery unit 12 according to the principle that dc signals can be superimposed on each other. Correspondingly, in this embodiment, the energy recovery unit 12 is further provided with an inverter 121. The inverter 121 is configured to superimpose the dc signals output by the rectifiers 112 of the test branches and invert them into ac signals having the same frequency and phase as the ac signals provided by the power supply unit, which are fed back to the frequency converter under test.

With continued reference to fig. 2, in some embodiments, an inductor-capacitor-inductor (LCL) filter 122 may also be included in the energy recovery unit 12. The lc-lc filter 122 may be disposed behind the inverter 121, and an input end of the lc-lc filter 122 is connected to an output end of the inverter 121, so as to receive the ac signal output by the inverter 121 and filter out harmonic components therein, so as to avoid adverse effects such as interference caused by the harmonic components in the ac signal on the power supply unit and the frequency converter to be tested.

In some embodiments, as shown in fig. 2, the loading device 20 further includes a filtering unit 23 disposed on each test branch. The filtering unit 23 is disposed between the frequency converter to be tested and the load loading device 11, and is configured to filter harmonic components in an output signal of the frequency converter to be tested.

It can be understood that the output signal of the frequency converter to be tested is generally an SPWM (sinusoidal pulse width modulation) signal, which includes some harmonic components, and these harmonic components may affect the load applying device 11, for example, cause additional loss to the reactor 111 in the load applying device 11, or cause interference to the operation of the rectifier 112. Therefore, the filter unit 23 is added to the loading device 20, so that the adverse effects can be effectively avoided.

In some embodiments, referring to fig. 2, the filtering unit 23 includes an inductance-capacitance (LC) filter 231. The inductance-capacitance filter is a passive filter formed by combining an inductance, a capacitance and a resistance, and can effectively filter one or more times of harmonic waves. In the embodiment of the present application, by disposing the inductor-capacitor filter 231 after the frequency converter to be tested, the SPWM modulated wave output by the frequency converter to be tested can be filtered into an approximately sinusoidal waveform, and part of the harmonics can be eliminated.

After filtering by the lc filter 231 described above, some harmonics of lower frequencies are effectively filtered out, but some harmonics of higher frequencies are also present. Therefore, in a further embodiment, the filtering unit 23 may further include an isolation transformer 232, and the isolation transformer 232 may be disposed after the lc-lc filter 231, and can effectively filter some odd harmonics, such as the third harmonic and the fifth harmonic generated by the frequency converter under test. In addition, since the isolation transformer converts the voltage and the current based on the principle of electromagnetic induction, and no direct current flows between the primary side and the secondary side thereof, the isolation transformer 232 also has an electrical isolation function in the loading device, and the safety of the loading device can be ensured.

The embodiment of the present application does not limit the specific type of the isolation transformer, and for example, the isolation transformer may be a star-delta isolation transformer, that is, one end of the isolation transformer 232 is connected in a star shape, and the other end is connected in a delta shape. The star-delta connected transformer can provide a loop for the third harmonic current, so that the induced electromotive force can be ensured to be sine wave, and the distortion is avoided.

The rectifier 112 described above can also be used to: following the variation in the amplitude and phase of the output voltage of the isolation transformer 232, the induced electromotive force is regulated at the secondary side of the isolation transformer 232 and a secondary winding current is generated. The current on the primary side of the isolation transformer 232 is equal to the sum of the current on the secondary side and the no-load current of the isolation transformer 232, which is obtained from the magnetomotive force balance equation of the transformer, so that the function of regulating the load can be realized according to the above principle. That is, for each test branch, the current parameter of the rectifier 112 is adjusted, so that the load on the test branch can be adjusted, the on-off of the contactor 21 on each test branch can be controlled, and the load of the whole aging loading device can be adjusted, thereby realizing the aging test of the frequency converter to be tested in a wider power range.

Based on the above principle, in some embodiments, the rectifier 112 may be configured to be connected to the control unit 13, so that the control unit 13 can send a control signal to the rectifier 112 according to the power section of the frequency converter to be tested, so as to adjust the current parameter of the rectifier 112, thereby implementing smooth adjustment of the load of the loading device therein.

In some embodiments, the frequency converter aging loading apparatus 20 may further include a power segment determining unit 24, configured to obtain a power segment of the frequency converter to be tested. The power segment determining unit 24 may be connected to the control unit 13, and may send the obtained power segment information of the frequency converter to be tested to the control unit 13.

The implementation manner of the power segment determining unit 24 may be many, and the embodiment of the present application is not particularly limited in this respect. The power segment determining unit may be, for example, an RFID reader, and at the same time, an RFID tag configured to record device information including the power segment of the frequency converter under test may be provided on the frequency converter under test. By reading the RFID tag with the RFID reader, the power section of the frequency converter to be tested can be determined. For another example, the power segment of the frequency converter to be tested may be determined based on an image identifier, specifically, for example, the power segment determining unit may be a code scanning gun, and the frequency converter to be tested has an image identifier (for example, a barcode or a two-dimensional code), the image identifier is configured to record device information including the power segment of the frequency converter to be tested, and the power segment of the frequency converter to be tested can be obtained by scanning the image identifier with the code scanning gun.

In some embodiments, the control unit may further include a PLC switching value monitoring device and a testing system, where the PLC switching value monitoring device and the testing system are used to perform real-time control and monitoring on the switching value of the entire aging loading device for the frequency converter, and meanwhile, a safety relay is added in the PLC switching value monitoring device to perform safe and reliable operation control on the entire device. The test system communicates with the frequency converter to be tested in real time through a port conforming to FC protocol, communicates with the AFEI inverter and the AFE inverter in real time through a port conforming to Modbus TCP protocol, and communicates with the PLC switching value monitoring device in real time through Profinet IO industrial Ethernet, so that the control of the whole frequency converter aging loading device is completed.

The aging test process of the aging loading device for the frequency converter provided by the embodiment of the present application is briefly described below in conjunction with the above description.

When testing is carried out, the whole frequency converter aging loading device is electrified, and the PLC switching value monitoring device carries out safety self-detection; the AFE inverter completes the self power-on process through the pre-charging device, and the whole loading device is started; connecting the frequency converter to be tested with a corresponding test fixture, confirming the model and the power section of the current frequency converter to be tested through FC protocol communication by a test system, and controlling the start operation of the current frequency converter to be tested; receiving an instruction of a test system through a ProfineI IO industrial Ethernet, controlling the output of the switching value by the PLC, and simultaneously carrying out safety monitoring on the corresponding input switching value to realize closed-loop control on the switching value; and the test system controls and modifies parameters of the AFEI inverter and the AFE inverter through a Modbus TCP protocol. The specific process is as follows:

a) controlling the frequency converter to be tested to operate;

b) the stable and reliable load is provided by setting the current parameters of the AFEI inverter, and meanwhile, the three-phase alternating current output by the secondary side of the isolation transformer is converted into direct current;

c) the AFE inverter inverts the direct current provided by the AFEI inverter into three-phase alternating current, and then the three-phase alternating current is fed back to the power supply unit after harmonics are eliminated through an inductance-capacitance-inductance (LCL) filter;

d) and after the aging test of the frequency converter to be tested is finished, disconnecting the frequency converter to be tested.

The embodiments described above are only a part of the embodiments of the present application, and not all of the embodiments. The order in which the above-described embodiments are described is not intended to be a limitation on the preferred order of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be understood that in the embodiment of the present application, "B corresponding to a" means that B is associated with a, from which B can be determined. It should also be understood that determining B from a does not mean determining B from a alone, but may also be determined from a and/or other information.

It should be understood that the term "and/or" herein is merely one type of association relationship that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

It should be understood that, in the various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (10)

1. A frequency converter aging loading device is characterized by comprising:

the input ends of the plurality of test branches are used for receiving the output current of the frequency converter to be tested, and the plurality of test branches are provided with load loading devices;

the input end of the energy recovery unit is connected with the output ends of the plurality of test branches, and the output end of the energy recovery unit is connected with the frequency converter to be tested and used for recovering and feeding back the output currents of the plurality of test branches to the frequency converter to be tested; and

and the control unit is connected with the plurality of test branches and used for controlling the on-off of the plurality of test branches according to the power section of the frequency converter to be tested so as to provide an aging test load matched with the power section of the frequency converter to be tested.

2. Frequency converter aging loading device according to claim 1,

and contactors are arranged on the test branches, connected with the control unit and used for being switched on and off under the control of the control unit according to the power section of the frequency converter to be tested.

3. Frequency converter aging loading device according to claim 1,

the load loading device comprises a reactor and a rectifier which are connected in series, wherein the output end of the rectifier is connected with the energy recovery unit and is used for inverting the output current of the reactor into a direct current signal and outputting the direct current signal to the energy recovery unit.

4. Frequency converter aging loading device according to claim 3,

the rectifier is connected with the control unit, so that the control unit can adjust the current parameters of the rectifier according to the power section of the frequency converter to be tested, and the load on the test branch circuit can be adjusted.

5. Frequency converter aging loading device according to claim 3,

the energy recovery unit comprises an inverter which is used for inverting the direct current signal output by the rectifier into an alternating current signal with the same frequency and phase as the alternating current signal provided by the energy recovery unit.

6. Frequency converter aging loading device according to claim 5,

the energy recovery unit further comprises an inductor-capacitor-inductor filter, and the inductor-capacitor-inductor filter is arranged between the inverter and the frequency converter to be tested and used for filtering harmonic waves in output signals of the inverter.

7. Frequency converter aging loading device according to claim 1,

the test branches further comprise a filtering unit, and the filtering unit is arranged between the frequency converter to be tested and the load loading device and used for filtering harmonic waves in output signals of the frequency converter to be tested.

8. Frequency converter aging loading device according to claim 7,

the filtering unit comprises an inductance-capacitance filter for filtering harmonic waves in the output signal of the frequency converter to be tested.

9. Frequency converter aging loading device according to claim 8,

the filtering unit further comprises an isolation transformer, and the isolation transformer is arranged between the inductance-capacitance filter and the load loading device and used for electrically isolating the test branch and filtering out odd harmonics generated by the frequency converter to be tested.

10. Frequency converter aging loading device according to claim 1,

the frequency converter aging loading device further comprises a power section acquisition unit, wherein the power section acquisition unit is connected with the control unit and used for acquiring and sending the power section of the frequency converter to be tested to the control unit.

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