Motor pair drags and water pump test system and variable frequency test power supply system thereof

Abstract

The application provides a motor pair-dragging and water pump test system and a variable frequency test power supply system thereof. The variable frequency test power supply system has two different loop states based on the switching state of each switch, so as to correspond to motor test and water pump test respectively, and the power supply loops in the two loop states share hardware. Therefore, the variable frequency test power supply system provided by the embodiment of the application can integrate the test of the tested motor and the tested water pump into one test system, so that the same test system can serve both motor pair-dragging energy feedback test and water pump direct drive test, thereby greatly reducing the initial investment, land occupation and long-term operation energy consumption cost of the test system.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a test system for a motor-to-pump system and a variable frequency test power supply system thereof. Background Technology

[0002] Electric motors and water pumps are indispensable power equipment in modern industry, and their performance testing is a crucial step in ensuring product quality, optimizing energy efficiency, and developing new products. Traditional testing platforms typically require separate test systems to perform load characteristic tests on motors and performance tests on water pumps separately. This not only leads to high construction costs and large site requirements, but also increases investment in power distribution infrastructure and daily operating energy consumption due to excessively high power quota configurations.

[0003] Specifically, in motor load testing, high-performance test platforms often employ a "coaxial-to-coaxial" configuration. The specific operating mode is as follows: the test motor connected to the shaft operates as a motor, drawing electrical energy from the test power supply and converting it into mechanical energy; while the load motor, coaxially connected, is forced to rotate, operating as a generator, converting the mechanical energy transmitted from the shaft into electrical energy. To recover this energy and reduce the load on the main power supply, the design allows the electrical energy generated by the load motor to be fed back to a common DC bus via an inverter, and then utilized by the test motor drive unit connected to this bus, thus forming an energy closed loop. While this scheme offers some energy savings, the capacity requirements for the rectifier unit (drawing power from the grid and supplying power to the bus) are relatively low, only needing to compensate for internal system losses.

[0004] However, the situation is completely different in pump performance testing. When the pump under test is driven by a motor, its output mechanical energy is entirely consumed by the load (usually simulating pipeline resistance or the pump itself, such as a trailer pump), and cannot be converted into regenerative electrical energy through another motor as in motor testing. Traditional industrial pump testing methods often involve "direct start + throttling adjustment," which leads to two major problems: First, the inrush current during motor startup can reach 6-8 times the rated current, forcing the power supply system (especially the rectifier) ​​to be configured with 2 times or even higher rated power to prevent startup overload; second, adjusting the flow rate through valves to achieve testing at different operating points wastes a significant amount of energy on the pressure drop generated by the valves, with an energy loss rate as high as 30% to 50%, which contradicts current energy conservation and carbon reduction goals.

[0005] Therefore, existing testing systems are difficult to integrate motor testing and water pump testing, often requiring separate investments in motor testing stations and water pump testing stations, resulting in redundant investment, low space utilization, and high overall energy consumption. Summary of the Invention

[0006] To address the existing technical problems, this application provides a motor-to-motor and water pump testing system and its variable frequency test power supply system that can test both motors and water pumps, thereby reducing the testing costs of motors and water pumps.

[0007] In a first aspect, embodiments of this application provide a variable frequency test power supply system for a motor-to-motor and water pump test system. The motor-to-motor and water pump test system is used to test the motor under test by coaxially towing the motor under test and the load motor, and is also used to test the water pump under test. The variable frequency test power supply system includes a common AC terminal, a rectifier unit, a DC bus, a first power conversion unit, a second power conversion unit, multiple switches, a motor under test connection terminal for connecting the motor under test, a water pump under test connection terminal for connecting the water pump under test, and a load motor connection terminal for connecting the load motor. The common AC terminal is used to receive AC power and is connected to the input terminal of the rectifier unit via a first switch, and to the AC terminal of the first power conversion unit via a second switch. The output terminal of the rectifier unit, the DC terminal of the first power conversion unit, and the DC terminal of the second power conversion unit are respectively connected to the DC bus. The AC terminal of the first power conversion unit is connected to the test motor terminal via a third switch and to the test water pump terminal via a fourth switch. The AC terminal of the second power conversion unit is connected to the load motor terminal via a fifth switch.

[0008] In some embodiments, the frequency conversion test power supply system further includes a controller, which is connected to each of the switches and is used to control the switching state of each switch according to the test mode. Specifically, when the test mode is the motor test mode, the controller controls the first switch, the third switch, and the fifth switch to be turned on, while the second switch and the fourth switch are turned off; when the test mode is the water pump test mode, the controller controls the first switch, the third switch, and the fifth switch to be turned off, while the second switch and the fourth switch are turned on.

[0009] In some embodiments, the frequency conversion test power supply system further includes a bus capacitor connected to the DC bus.

[0010] In some embodiments, the capacitance value of the bus capacitor is configured to satisfy the following: during the peak power surge of the test water pump at startup, the output power of the second power conversion unit in rectification mode is 1.2 times the rated power of the test water pump.

[0011] In some embodiments, the bus capacitor includes a thin-film capacitor and a supercapacitor connected in parallel.

[0012] In some embodiments, the frequency conversion test power supply system further includes an isolation transformer connected between the power grid and the common AC terminal, for drawing power from the power grid and outputting AC power to the common AC terminal.

[0013] In some embodiments, the first power conversion unit and / or the second power conversion unit includes a full-power self-commutating inverter.

[0014] In some embodiments, the full-power self-commutating inverter incorporates an LCL filter, which is used to filter the current output from the inverter bridge in the full-power self-commutating inverter.

[0015] In some embodiments, the first power conversion unit and / or the second power conversion unit are IGBT bidirectional inverter units.

[0016] Secondly, embodiments of this application provide a test system for a motor-driven pump, including a load motor, a coaxial cable, and a frequency conversion test power supply system as described in any of the foregoing items; The load motor is used to connect to the load motor connection terminal in the frequency conversion test power supply system when the motor-paired pump test system is under motor test, and the coaxial connector is used to connect the load motor and the test motor coaxially.

[0017] The variable frequency test power supply system for the motor-to-drive and water pump test system provided in this application embodiment has two different circuit states based on the switching states of each switch, corresponding to the motor test and the water pump test respectively. The power circuits in both circuit states share a common AC terminal, DC bus, and second power conversion unit. Therefore, based on the variable frequency test power supply system provided in this application embodiment, the tests of the tested motor and the tested water pump can be integrated into one test system. This allows the same test system to serve both the motor-to-drive energy feedback test and the water pump direct drive test, thereby greatly reducing the initial investment, floor space, and long-term energy consumption costs of the test system. Attached Figure Description

[0018] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the structure of a variable frequency test power supply system for testing motors and water pumps, provided in some embodiments of this application.

[0019] Figure 2 This is a schematic diagram of the structure of a frequency conversion test power supply system in the first loop state, provided for some embodiments of this application.

[0020] Figure 3 This is a schematic diagram of the structure of a frequency conversion test power supply system in the first loop state, provided for some embodiments of this application.

[0021] Figure 4 This is a schematic diagram comparing the energy storage characteristics of different capacitor types. Detailed Implementation

[0022] The technical solution of this application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] To reduce the cost of motor and pump testing, there is an urgent need for a testing system that can integrate the two into one. Based on this, embodiments of this application provide a motor-to-motor and pump testing system and its variable frequency power supply system. The variable frequency power supply system provided in this application, through ingenious topology design and control logic, enables the same testing system to serve both motor-to-motor energy feedback testing and direct pump drive testing, thereby significantly reducing initial investment, floor space, and long-term energy consumption costs.

[0024] The motor-paired and water pump test system of this embodiment is used to test the motor under test by coaxially pairing the test motor and the load motor, and is also used to test the water pump under test. The frequency converter test power supply system is used to supply power to the motor-paired and water pump test system. The following will combine... Figures 1 to 4 The power supply system for testing motors and water pumps and their frequency conversion tests provided in the embodiments of this application will be described accordingly.

[0025] Please see Figure 1 The diagram shown is a structural schematic of the variable frequency test power supply system for the motor-to-motor and water pump test provided in this embodiment. The variable frequency test power supply system in this embodiment includes a common AC terminal 11, a rectifier unit 12, a DC bus 13, a first power conversion unit 14, a second power conversion unit 15, multiple switches, a test motor connection terminal 16 for connecting the test motor 20, a test water pump connection terminal 17 for connecting the test water pump 30, and a load motor connection terminal 18 for connecting the load motor 40. When the motor-to-motor and water pump test system tests the test motor 20, the test motor 20 is coaxially connected to the load motor 40 via a coaxial connector 50, thereby enabling the test of the test motor 20 using a motor-to-motor configuration.

[0026] The common AC terminal 11 is used to receive AC power and is connected to the input terminal of the rectifier unit 12 via a first switch K1, and to the AC terminal of the first power conversion unit 14 via a second switch K2. The output terminal of the rectifier unit 12, the DC terminal of the first power conversion unit 14, and the DC terminal of the second power conversion unit 15 are respectively connected to the DC bus 13. The AC terminal of the first power conversion unit 14 is connected to the test motor connection terminal 16 via a third switch K3, and to the test water pump connection terminal 17 via a fourth switch K4. The AC terminal of the second power conversion unit 15 is connected to the load motor connection terminal 18 via a fifth switch K5. Specifically, the first power conversion unit 14 converts the DC power input at its DC terminal into AC power, which is then output from its AC terminal; the second power conversion unit 15 converts the AC power input at its AC terminal into DC power, which is then output from its DC terminal. That is, in this embodiment, the first power conversion unit 14 has the function of converting DC power into AC power, and the second power conversion unit 15 has the function of converting AC power into DC power. Furthermore, in this embodiment, the multiple switches of the frequency conversion test power supply system include the first switch K1 to the fifth switch K5.

[0027] The AC power received at the common AC terminal 11 comes from a transformer, power grid, or other power source. The rectifier unit 12 is used to rectify the AC power at the common AC terminal 11 when the first switch K1 is in the ON state, and output DC power to the DC bus 13. The DC bus is used to provide a common DC voltage platform for the motor-to-trailer and water pump test system.

[0028] In the variable frequency test power supply system provided in this application embodiment, the common AC terminal 11 is connected to the rectifier unit 12 and the second power conversion unit 15 through corresponding switches. The load motor 40 can be connected to the DC bus 13 through the second power conversion unit 15. The second power conversion unit 15 can convert the AC power obtained from the common AC terminal 11 or the load motor 40 into DC power and output it to the DC bus 13. The first power conversion unit 14 can obtain DC power from the DC bus 13 and convert it into AC power to output to the tested motor 20 or the tested water pump 30. Therefore, the variable frequency test power supply system provided in this application embodiment has two circuit states, as shown below. Figure 2 and Figure 3 As shown, where Figure 2 For the frequency converter test power supply system in the first circuit state, Figure 3This is a variable frequency test power supply system in the second circuit state. When the first switch K1, the third switch K3, and the fifth switch K5 are in the conducting state, and the second switch K2 and the fourth switch K4 are in the open state, the variable frequency test power supply system is in the first circuit state. The AC power from the common AC terminal 11 is input to the rectifier unit 12 via the first switch K1 for rectification, and then input to the DC bus 13. The first power conversion unit 14 obtains DC power from the DC bus 13, converts it into AC power, and then supplies it to the test motor 20 via the third switch K3 to power the test motor 20, so that the test motor 20 is in the test state. During the operation of the test motor 20, electrical energy is converted into mechanical energy, and it is coaxially connected to the load motor 40 through the coaxial connector 50, thereby driving the load motor 40 to work, so that the load motor 40 is in the generating state, that is, converting mechanical energy into electrical energy. The AC power output by the load motor 40 is input to the second power conversion unit 15 via the fifth switch K5, and then converted into DC power by the second power conversion unit 15 and fed back to the DC bus 13. When the first switch K1, the third switch K3, and the fifth switch K5 are in the open state, and the second switch K2 and the fourth switch K4 are in the closed state, the frequency converter test power supply system is in the second loop state. The AC power from the common AC terminal 11 is input to the second power conversion unit 15 via the second switch K2, and then converted into DC power by the second power conversion unit 15 before being input to the DC bus 13. The first power conversion unit 15 takes DC power from the DC bus 13, converts it into AC power, and outputs it to the tested water pump 30 via the fourth switch K4 to power the tested water pump 30, thus putting the tested water pump 30 into the test state. When the frequency converter test power supply system is in the first loop state, the power supply loop 1, i.e., the energy feedback loop, is composed of the common AC terminal 11, the first switch K1, the rectifier unit 12, the DC bus 13, the first power conversion unit 14, the third switch K3, the tested motor 20, the load motor 40, the fifth switch K5, and the second power conversion unit 15. The energy feedback loop here refers to the electrical energy supplying the test motor 20 based on the mutual drive between the test motor 20 and the load motor 40, which is then converted into electrical energy by the load motor 40 and fed back to the DC bus 13 via the second power conversion unit 15. When the frequency conversion test power supply system is in the second loop state, the power circuit 2 consists of the common AC terminal 11, the second switch K2, the second power conversion unit 15, the DC bus, the first power conversion unit 14, the fourth switch K4, and the test water pump 17.

[0029] The power supply circuit provided in this application embodiment has a first circuit state for supplying power to the test motor 20 based on the motor-driven method and a second circuit state for supplying power to the test motor 30 based on the motor-driven method. The power supply circuit 1 in the first circuit state and the power supply circuit 2 in the second circuit state share a common AC terminal 11, a DC bus 13, and a second power conversion unit 14. Therefore, based on the frequency conversion test power supply system provided in this application embodiment, the tests of the test motor 20 and the test water pump 30 can be integrated into one test system. This allows the same test system to serve both the motor-driven energy feedback test and the direct drive test of the water pump, thereby greatly reducing the initial investment, floor space, and long-term energy consumption cost of the test system.

[0030] In some embodiments, the frequency conversion test power supply system includes a controller ( Figures 1 to 3 (Not shown in the diagram), the controller is connected to each switch in the power circuit and is used to control the switching state of each switch according to the test mode. Specifically, when the test mode is motor test mode, the controller controls the first switch K1, the third switch K3, and the fifth switch K5 to be turned on, and the second switch K2 and the fourth switch K4 to be turned off; when the test mode is water pump test mode, the controller controls the first switch K1, the third switch K3, and the fifth switch K5 to be turned off, and the second switch K2 and the fourth switch K4 to be turned on.

[0031] The frequency conversion test power supply system provided in this embodiment automatically controls the switching state of each switch according to the test mode through the controller, thereby realizing the automatic switching between the first circuit state and the second circuit state of the frequency conversion test power supply system, and thus realizing the automatic switching of the test mode of the motor-to-drive and water pump test systems. It can not only provide power for motor test and water pump test separately, but also is simple to operate and can reduce labor costs.

[0032] In some embodiments, the controller can be a control device with a display screen or a control device connected to a display screen. The user can input the test mode based on the display interface. The controller obtains the test mode information currently input by the user based on the display interface, and controls each switch to be in the corresponding switching state according to it, so that the frequency conversion test power supply system is in the loop state matching the current test mode, thereby supplying power to the test motor 20 or the test water pump 30, so that the test motor 20 or the test water pump 30 enters the test state.

[0033] Please continue reading. Figures 1 to 3 As shown, in some embodiments, the frequency converter test power supply system further includes a bus capacitor 19 connected to the DC bus 13. Specifically, one end of the bus capacitor 19 can be connected to the DC bus 13, and the other end is grounded. It should be noted here that... Figures 1 to 3The bus capacitor 19 in the diagram is only represented by a structural frame to indicate that it is connected to the DC bus 13, but it does not mean that both ends of the bus capacitor 19 are connected to the DC bus 13. The bus capacitor 19 can release electrical energy to the DC bus 13 to replenish the DC bus 13, and it can also draw electrical energy from the DC bus 13 to charge itself.

[0034] During the water pump test, the mechanical energy converted from electrical energy by the tested water pump 30 cannot be recovered and fed back to the DC bus 13. The second power conversion unit 15 is in rectification mode to convert the electricity from the common AC terminal into DC through controllable rectification and supply it to the DC bus 13. Power is then supplied to the tested water pump 30 through the DC bus 13 and the first power conversion unit 14. In this embodiment, due to the presence of the bus capacitor 19, during the water pump test, the bus capacitor 19 can supply electrical energy to the DC bus 13. With the energy storage and buffering effect of the bus capacitor 19, the power output of the second power conversion unit 15 can be effectively reduced. For example, without the bus capacitor 19, the power output of the second power conversion unit 15 during the water pump test needs to be more than twice the rated power of the tested water pump 30. However, in this embodiment, the power output of the second power conversion unit 15 can be reduced to 1.2 times the rated power of the tested water pump 30. Therefore, the frequency conversion test power supply system provided in this application embodiment, based on the setting of bus capacitor, can solve key problems such as bidirectional energy flow and bus voltage stability when the dual test systems of motor and water pump are combined, and the comprehensive energy saving rate is more than 30%.

[0035] In some embodiments, in order to effectively reduce the output power of the second power conversion unit 15 in rectification mode to 1.2 times the rated power of the test water pump 30, during the peak power period of the test water pump at startup, the output power of the second power conversion unit 15 in rectification mode is 1.2 times the rated power of the test water pump 30.

[0036] Bus capacitor 19 plays a dual role as an energy buffer and voltage stabilizer in the frequency conversion test power supply system. Its energy storage process follows the capacitor energy formula E=1 / 2CU², where C is the capacitance of bus capacitor 19 and U is the voltage between the two plates of bus capacitor 19, which is also the bus voltage of DC bus 13. When there is a momentary imbalance between the power output of the second power conversion unit 15 and the power required by the tested water pump 30, i.e., when there is an energy difference, bus capacitor 19 dynamically adjusts the energy difference through charging and discharging. For example, in some embodiments, during the start-up phase of the water pump test, the instantaneous power of the tested water pump 3 may reach more than three times its rated power. At this time, the output power Prect of the second power conversion unit 15 is designed to be 1.2 times the rated power of the tested water pump 30, i.e., Prect=1.2Pn. Wherein, Pn is the rated power of the water pump under test 30. The portion of the power output by the second power conversion unit 13 that is insufficient for the instantaneous power of the water pump under test 30 is released to the DC bus 13 by the bus capacitor 19 to compensate for the energy of the water pump under test 30. The formula for calculating the required compensation energy is as follows: ΔE=∫(Pload-Prect)dt=1 / 2C(U1²-U2²); Where ΔE is the required supplemental energy, Pload is the instantaneous power of the tested water pump 30, and U1 and U2 are the bus voltages on the DC bus 13 before and after the bus capacitor 19 discharges. When the frequency conversion test power supply system is running stably, the bus capacitor 19 mainly absorbs the ripple power output by the second power unit 15, so that the bus voltage fluctuation is controlled within ±5% of the rated value.

[0037] Please see Figure 4 As shown, it is a schematic diagram comparing the energy storage characteristics of different capacitor types. In this embodiment, the bus capacitor 19 adopts a hybrid energy storage architecture of film capacitor and supercapacitor. That is, the bus capacitor 19 includes film capacitor and supercapacitor connected in parallel. In this way, the low ESR characteristics of film capacitor can be used to suppress high frequency ripple, while the high power density of supercapacitor can be used to deal with instantaneous power surges. This ensures that the bus voltage recovery time of the motor-to-trailer and water pump test system is controlled within 5ms when the tested water pump 30 suddenly increases to 200% of its rated power.

[0038] In the variable frequency test power supply system provided in this application embodiment, the core of the design of the second power conversion unit 15 outputting 1.2 times the rated power of the tested water pump 30 during the water pump test lies in establishing a dynamic matching model between the output power of the second power conversion unit and the load characteristics of the tested water pump 30. Let the rated power of the tested water pump 30 be Pn, the rated current be In, and the motor efficiency be η. Then, the power Prated output by the second power conversion unit 15 must satisfy: Prated = 1.2Pn = 1.2 × (In × Un) / η, where Un is the rated voltage of the motor of the tested water pump 30. In related technologies, designing the power output of the second power conversion unit 15 as more than twice the rated power of the tested water pump 30 stems from not considering the dynamic changes in the load characteristics of the tested water pump 30. However, in reality, the peak power duration during the test start-up process of the tested water pump 30 is only 0.3-0.5 seconds, and the energy released through the bus capacitor 19 can compensate for the energy difference during this stage. Based on ΔE=Prated×Δt, according to the law of conservation of energy, the following formula can be obtained: C×(Umax²-Umin²) / 2=ΔP×Δt; Wherein, ΔP is the power difference between the peak power of the tested water pump 30 and the output power of the second power conversion unit 15 in rectification mode. In some embodiments, ΔP = 0.8Pn, Δt = 0.4s, then according to the above formula, the minimum capacitance C required for the bus capacitor 19 can be obtained, and its calculation formula is as follows: C = 1.6PnΔt / (Umax² - Umin²); Wherein, Umax and Umin are the maximum and minimum voltages of bus capacitor 19, respectively.

[0039] Please continue reading. Figures 1 to 3 As shown, in some embodiments, the frequency conversion test power supply system further includes an isolation transformer 10 connected between the power grid 60 and the common AC terminal 11. The isolation transformer 10 is used to draw power from the power grid 60 and output AC power to the common AC terminal 11. Furthermore, the frequency conversion test power supply system may further include a sixth switch K6 connected between the isolation transformer 10 and the power grid 60, so as to realize the switching between the frequency conversion test power supply system and the power grid 60 through the sixth switch K6, thereby improving the power supply safety of the frequency conversion test power supply system.

[0040] Please continue reading. Figures 1 to 3As shown, in some embodiments, the first power conversion unit 14 includes a full-power self-commutating inverter. A full-power self-commutating inverter is a power electronic device that can completely convert direct current (DC) into alternating current (AC). Its core feature is that it uses fully controlled power devices (such as IGBTs, GTOs, etc.) to achieve self-commutation, that is, it can autonomously switch the current direction without relying on the grid to provide commutation voltage.

[0041] In some embodiments, the second power conversion unit 15 can also be a full-power self-commutating inverter, and the second power conversion unit 15 can also convert AC power into DC power, that is, the second power conversion unit 15 is a bidirectional power conversion unit, so that it can both obtain DC power from the DC bus 13 and convert it into AC power for output, and convert the AC power provided by the common AC terminal 11 or the load motor 18 into DC power for output to the DC bus 13. Specifically, the second conversion unit 15 also has a controllable rectification state to rectify the AC power into DC power for output to the DC bus 13.

[0042] In some embodiments, the first power conversion unit 14 and the second power conversion unit 15 may be the same, for example, both may be bidirectional power conversion units, so that they can both realize AC to DC conversion and DC to AC conversion, thereby improving the application flexibility of the frequency conversion test power supply system.

[0043] Of course, in other embodiments, the first power conversion unit 14 and the second power conversion unit 15 may be different, and they are not limited to bidirectional power conversion units. For example, in some embodiments, the first power conversion unit 14 is a single-phase DC / AC converter, and the second power conversion unit 15 is a single-phase AC / DC converter.

[0044] In some embodiments, the first power conversion unit 14 and / or the second power conversion unit 15 are IGBT bidirectional inverter units, that is, the first power conversion unit 14 and / or the second power conversion unit include an IGBT bidirectional inverter. The IGBT bidirectional inverter can be, but is not limited to, a three-phase bridge arm inverter, where the upper and lower arms of each half-bridge of the three-phase bridge arm inverter are respectively composed of an IGBT and diodes connected in parallel across the IGBT. Based on the on / off control of the IGBT, the IGBT bidirectional inverter inverts DC power into AC power, and based on each diode, it can rectify AC power into DC power, thereby realizing bidirectional power conversion.

[0045] In some embodiments, the aforementioned full-power self-commutating inverter incorporates an LCL filter, which is used to filter the current output from the inverter bridge in the full-power self-commutating inverter. In some embodiments, the full-power self-commutating inverter with an incorporated LCL filter is a three-level full-bridge IGBT self-commutating inverter, and the LCL filter is connected to the AC terminal of the three-level full-bridge IGBT self-commutating inverter.

[0046] During motor testing, a coaxial drive scheme is adopted. The test motor 20 is connected to the load motor 40 through a coaxial connector 50. The load motor 40 operates in generator mode, and its output AC power is converted into DC power by a three-level full-bridge IGBT self-commutating inverter. After being filtered by an LCL filter, it is injected into the DC bus 13. Energy is stabilized at the DC bus 13 through the outer voltage loop and the inner current loop, ensuring that the feedback energy is directly consumed by the test motor 20, thereby improving the overall efficiency of the frequency conversion test power supply system by more than 85%.

[0047] In some embodiments, this application also provides a motor-to-tow and water pump test system, which may include, but is not limited to, a load motor 40, a coaxial connector 50, and a power supply circuit provided in any embodiment of this application. The load motor 40 is used to connect to the load motor connection terminal 18 in the frequency converter test power supply system when the motor-to-tow and water pump test system is in motor testing mode, and the coaxial connector 50 is used to coaxially connect the load motor 40 and the test motor 20.

[0048] Based on the variable frequency test power supply system with dual-loop operation provided in this application embodiment, the motor-to-motor and water pump test system, while testing the motor, does not require an additional power conversion unit. It can perform water pump testing by switching the switching states of various switches. That is, the water pump test and motor test share the same variable frequency test power supply system, thus enabling the motor-to-motor and water pump test system to test both the motor and the water pump, achieving a unified dual-test system. Furthermore, after the integration of the two systems, the water pump test can achieve a significant energy-saving effect. By controlling the switches in the variable frequency test power supply system, the control logic switching between the motor-to-motor test and the water pump test is realized. This allows the energy feedback during motor testing and the power supply during water pump testing to share a single main circuit, reducing the site area occupied by the motor and water pump test system by 50% and the initial investment by more than 40%.

[0049] Furthermore, the test system provided in this application embodiment achieves hardware reuse for motor and water pump tests through DC bus energy hub and IGBT self-commutation technology, reduces the power demand on the grid side by utilizing energy feedback during motor testing, and reduces the rectifier capacity by buffering the bus capacitor during water pump testing.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the ways in which this application may be implemented. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0051] In the description of this application, unless otherwise stated, "a plurality of" means two or more. Furthermore, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0052] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A variable frequency test power supply system for a motor-to-tow pump test system, characterized in that, The motor-paired and water pump test system is used to test the motor under test by coaxially pairing the motor under test and the load motor, and is also used to test the water pump under test. The frequency conversion test power supply system includes a common AC terminal, a rectifier unit, a DC bus, a first power conversion unit, a second power conversion unit, multiple switches, a motor under test connection terminal for connecting the motor under test, a water pump under test connection terminal for connecting the water pump under test, and a load motor connection terminal for connecting the load motor. The common AC terminal is used to receive AC power and is connected to the input terminal of the rectifier unit via a first switch, and to the AC terminal of the first power conversion unit via a second switch. The output terminal of the rectifier unit, the DC terminal of the first power conversion unit, and the DC terminal of the second power conversion unit are respectively connected to the DC bus. The AC terminal of the first power conversion unit is connected to the test motor terminal via a third switch and to the test water pump terminal via a fourth switch. The AC terminal of the second power conversion unit is connected to the load motor terminal via a fifth switch.

2. The frequency conversion test power supply system according to claim 1, characterized in that, It also includes a controller, which is connected to each of the switches and is used to control the switching state of each switch according to the test mode; Specifically, when the test mode is the motor test mode, the controller controls the first switch, the third switch, and the fifth switch to be turned on, while the second switch and the fourth switch are turned off; when the test mode is the water pump test mode, the controller controls the first switch, the third switch, and the fifth switch to be turned off, while the second switch and the fourth switch are turned on.

3. The frequency conversion test power supply system according to claim 1, characterized in that, It also includes a bus capacitor connected to the DC bus.

4. The frequency conversion test power supply system according to claim 3, characterized in that, The capacitance value of the bus capacitor is configured to satisfy the following condition: during the peak power period of the instantaneous start-up of the test water pump, the output power of the second power conversion unit in rectification mode is 1.2 times the rated power of the test water pump.

5. The frequency conversion test power supply system according to claim 4, characterized in that, The bus capacitor includes thin-film capacitors and supercapacitors connected in parallel.

6. The frequency conversion test power supply system according to claim 1, characterized in that, It also includes an isolation transformer connected between the power grid and the common AC terminal, for drawing power from the power grid and outputting AC power to the common AC terminal.

7. The frequency conversion test power supply system according to claim 1, characterized in that, The first power conversion unit and / or the second power conversion unit include a full-power self-commutating inverter.

8. The frequency conversion test power supply system according to claim 7, characterized in that, The full-power self-commutating inverter has a built-in LCL filter, which is used to filter the current output by the inverter bridge in the full-power self-commutating inverter.

9. The frequency conversion test power supply system according to claim 1, characterized in that, The first power conversion unit and / or the second power conversion unit are IGBT bidirectional inverter units.

10. A test system for motor-driven tow trucks and water pumps, characterized in that, Includes a load motor, a coaxial cable, and a frequency conversion test power supply system as described in any one of claims 1 to 9; The load motor is used to connect to the load motor connection terminal in the frequency conversion test power supply system when the motor-paired pump test system is under motor test, and the coaxial connector is used to connect the load motor and the test motor coaxially.

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