Inverter aging detection device and inverter aging detection system

Abstract

The utility model discloses an inverter aging detection device and an inverter aging detection system, and belongs to the technical field of power electronics. The inverter aging detection device comprises a multi-voltage power supply unit which is provided with a plurality of output ends and is configured to provide output voltages with different amplitudes through the output ends; the switching unit comprises a plurality of switching circuits and at least one output line, the first ends of the switching circuits are correspondingly and electrically connected with the output ends of the multi-voltage conversion unit, the second ends of the switching circuits are connected in parallel and electrically connected with the first ends of the output lines, and the second ends of the output lines are used for being connected with an inverter; the alternating current input end of the rectification unit is electrically connected with the output line, the alternating current input end of the rectification unit is used for being connected with the alternating current output end of the tested inverter, and the direct current output end of the rectification unit is used for being connected with the direct current input end of the tested inverter. The number of devices and occupied space are reduced, energy can be recycled, and energy is saved.

Description

Inverter aging test device and inverter aging test system Technical Field

[0001] This application belongs to the field of power electronics technology, and in particular relates to an inverter aging detection device and inverter aging detection system. Background Technology

[0002] Before an inverter is put into use, it needs to undergo factory aging tests to ensure the reliability of the product's power devices and the integrity of its inverter function. In traditional testing processes, different voltage levels require different testing equipment, involving a large number of electrical devices. The aging test process also results in significant power loss, leading to a waste of cost and space. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes an inverter aging test device and an inverter aging test system, which achieves multiple voltage outputs through a single power supply circuit, so that the input voltage on the DC side of the inverter matches the test requirements, reduces the number of devices and space occupation, and enables energy reuse, thus saving energy.

[0004] In a first aspect, this application provides an inverter aging detection device, comprising:

[0005] The multi-voltage power supply unit has multiple output terminals and is configured to provide output voltages of different amplitudes through each output terminal;

[0006] The switching unit includes multiple switching circuits and at least one output line. The first terminal of each switching circuit is electrically connected to each output terminal of the multi-voltage conversion unit, and the second terminal of each switching circuit is connected in parallel with each other and electrically connected to the first terminal of the output line.

[0007] At least one rectifier unit is provided. The AC input terminal of the rectifier unit is electrically connected to the output line. The AC input terminal of the rectifier unit is used to connect to the AC output terminal of the inverter under test, and the DC output terminal of the rectifier unit is used to connect to the DC input terminal of the inverter under test.

[0008] According to one embodiment of this application, the switching circuit includes:

[0009] The first branch, the first end of the first branch is connected to the output end of the multi-voltage conversion unit, and the second end of the first branch is electrically connected to the first end of the output line;

[0010] The main contact of the first contactor is located in the first branch circuit;

[0011] The inverter aging detection device also includes:

[0012] The main control unit includes multiple first contactor coils, and the first contactor coils are coupled to the main contacts of the first contactors.

[0013] According to one embodiment of this application, the main control unit further includes:

[0014] A programmable logic controller with multiple output ports;

[0015] Multiple second branches are connected in parallel, and each second branch includes a relay and a first contactor coil connected in series. The coil of each relay is connected to the corresponding output port of the programmable logic controller.

[0016] According to one embodiment of this application, the main control unit further includes:

[0017] An interlocking circuit includes multiple first contactor auxiliary contacts, which are respectively disposed on each second branch, and each second branch is provided with at least one first contactor auxiliary contact from another second branch. The first contactor auxiliary contact is disconnected when the corresponding first contactor main contact is engaged.

[0018] According to one embodiment of this application, the number of first contactor auxiliary contacts provided on each second branch is equal to the number of the remaining second branches, and each first contactor auxiliary contact on any second branch comes from a different branch.

[0019] According to one embodiment of this application, the multi-voltage power supply unit includes:

[0020] A multi-winding transformer has a primary winding and multiple secondary windings. The primary winding is used to connect to the power grid, and the secondary windings are connected to the first terminal of each switching circuit.

[0021] Secondly, this application provides an inverter aging detection system, including at least one of the aforementioned inverter aging detection devices and an inverter, wherein the inverter is electrically connected to the inverter aging detection device.

[0022] According to several embodiments of the inverter aging test apparatus and inverter aging test system of this application, the multi-voltage power supply unit can provide output voltages of different amplitudes to adapt to inverters of different voltage levels. Multi-voltage output is achieved through a single power supply circuit, reducing the number of devices and space occupation. During the aging test of the inverter, the converted AC output is transmitted to the AC input terminal of the rectifier unit, and then rectified by the rectifier unit before being supplied to the inverter under test, realizing the reuse of energy and saving energy.

[0023] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0024] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 is a structural block diagram of the inverter aging detection device provided in an embodiment of this application;

[0026] Figure 2 is a circuit diagram of the inverter aging detection device provided in an embodiment of this application;

[0027] Figure 3 is one of the circuit diagrams of the main control unit provided in the embodiments of this application;

[0028] Figure 4 is a second circuit diagram of the main control unit provided in the embodiments of this application.

[0029] Figure label:

[0030] Multi-voltage power supply unit 100, switching unit 200, switching circuit 210, output line 220, first branch 211, programmable logic controller 311, interlock circuit 312, second branch 313, power grid 400, inverter under test 500, rectifier unit 600, main contacts of first to third contactors KM1~KM3, coils of first to third contactors KM1'~KM3', auxiliary contacts of first contactor KM1", relay K, relay coil K', air switch QF1, fan M, power-on button S, power-on indicator light L, fan M. Detailed Implementation

[0031] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0032] In the following description, a "circuit" refers to a conductive loop consisting of at least one element or sub-circuit connected by an electrical or electromagnetic link. When an element or circuit is said to be "coupled to" or "connected to" another element, or when an element / circuit is said to be "coupled at" or "connected at" two nodes, it can be directly coupled to or connected to the other element, or there may be intermediate elements. The connection between elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there are no intermediate elements between them.

[0033] In the description, the terms "first," "second," etc., are used to distinguish similar objects, not to describe a specific order or sequence. It should be understood that such numerical descriptors can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0034] Furthermore, the use of terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0035] Before an inverter is put into use, it needs to undergo factory aging tests to ensure the reliability of the power devices and the integrity of the inverter function. In related technologies, products of different voltage levels require different testing equipment, involving a large number of electrical devices. The aging test process has significant power loss, resulting in wasted cost and space.

[0036] Figure 1 illustrates an inverter aging test device provided in an embodiment of this application. Referring to Figure 1, an embodiment of this application proposes an inverter aging test device, including: a multi-voltage power supply unit 100, a switching unit 200, and at least one rectifier unit 600. The multi-voltage power supply unit 100 has multiple output terminals and is configured to provide output voltages of different amplitudes through each output terminal; the switching unit 200 includes multiple switching circuits 210 and at least one output line 220, the first terminal of each switching circuit 210 is electrically connected to each corresponding output terminal of the multi-voltage switching unit, the second terminal of each switching circuit 210 is connected in parallel with each other and electrically connected to the first terminal of the output line 220; the AC input terminal of the rectifier unit 600 is electrically connected to the output line, the AC input terminal of the rectifier unit is used to connect to the AC output terminal of the inverter under test 500, and the DC output terminal of the rectifier unit 600 is used to connect to the DC input terminal of the inverter under test 500.

[0037] The multi-voltage power supply unit 100 is mainly used to provide two or more voltage outputs with different amplitudes. The multi-voltage power supply unit 100 can be composed of an input terminal, a voltage conversion unit, and an output terminal. The input terminal of the multi-voltage power supply unit 100 receives the voltage output from the power supply device, the voltage conversion unit is responsible for converting the input voltage into multiple required voltage levels, and the output terminal is used to output these different voltage levels. The specific circuitry and structure of the voltage conversion unit can be selected according to the actual application scenario and are not limited here. For example, the voltage conversion unit may include a transformer, a voltage regulator, or a switching power supply.

[0038] The specific structure of the power supply device can be selected according to the actual application scenario, and is not limited here. For example, the power supply device can be the power grid or a DC power source. It is understood that when the power supply device is the power grid, the DC side of the inverter under test 500 needs to be connected to a rectifier unit to convert the AC voltage output by the multi-voltage power supply unit 100 into DC voltage.

[0039] The switching unit 200 is mainly used to selectively output a voltage of a certain amplitude to the inverter under test 500 at the same time. Each switching circuit 210 is electrically connected to each output terminal of the multi-voltage conversion unit, and the switching circuit 210 can switch between on and off states. When a certain switching circuit 210 is on, the test voltage output from the output terminal of the multi-voltage conversion unit 100 connected to it can be provided to the inverter under test 500.

[0040] It should be noted that each output line 220 is electrically connected to one inverter under test (UTD) 500. Since the multi-voltage power supply unit 100 can only selectively output one voltage level at a time, when performing aging tests on multiple UTDs 500 simultaneously, it is necessary to ensure that the multiple UTDs 500 are at the same voltage level. The number of output lines 220 can be selected according to the actual application scenario and is not limited here. For example, the number of output lines 220 can be 3, 4, or 5, etc.

[0041] It is understandable that the number of output lines 220 determines the number of inverters 500 under test at the same voltage level that the inverter under test aging test device can simultaneously test. For example, when there are 3 output lines 220, it means that the inverter under test aging test device of this application can simultaneously perform aging tests on 3 inverters 500 under test at the same voltage level.

[0042] The number of rectifier units 600 is the same as the number of output lines 220. The AC input terminal of each rectifier unit 600 is electrically connected to the second terminal of the output line 220, enabling the AC voltage output from the multi-voltage power supply unit 100 to be converted to DC voltage. The DC output terminal of each rectifier unit 600 can be connected to the DC input terminal of an inverter under test 500, providing a stable and clean DC power supply to the inverter under test 500. Connecting the AC input terminal of the rectifier unit 600 to the AC output terminal of the inverter under test 500 allows the AC power converted and output during the aging test of the inverter under test 500 to be transmitted to the AC input terminal of the rectifier unit 600. The rectifier unit 600 then rectifies the AC power before supplying it to the inverter under test 500, achieving energy reuse and saving energy.

[0043] The specific structure and function of the rectifier unit 600 are already based on relatively mature technologies, and will not be elaborated here.

[0044] In some embodiments, a second contactor is provided on the line between the AC output terminal of the inverter under test 500 and the AC input terminal of the rectifier unit 600. The number of second contactors can be the same as the number of inverters under test 500 being tested simultaneously, forming a controllable conduction loop between each inverter under test 500 and its corresponding rectifier unit 600, thereby achieving flexible control of the testing state.

[0045] The specific method for aging testing the inverter under test 500 can be selected according to the actual application scenario and is not limited here. The aging electrical parameters of the inverter under test 500 can be its output voltage under full load conditions, or its efficiency under full load conditions, etc. As an example, after the main control unit controls the multi-voltage power supply unit 100 to output a voltage of appropriate amplitude according to the operating voltage of the inverter under test 500, the output voltage of the AC side of the inverter under test 500 can be detected under full load conditions. When the output voltage of the AC side of the inverter under test 500 is within the allowable range, it is determined that the inverter under test 500 has not aged. The allowable range can be the theoretical output voltage Uo ±5%.

[0046] In some embodiments, the inverter aging detection device further includes a main control unit. The main control unit is electrically connected to each switching circuit 210, and is configured to determine the test voltage of the inverter and control the corresponding switching circuit 210 to turn on in order to provide the test voltage to the inverter 500.

[0047] The method by which the main control unit determines the test voltage of the inverter under test 500 can be selected according to the actual application scenario, and is not limited here. For example, the main control unit can determine the rated voltage of the inverter under test 500 through the Modbus protocol, or identify the rated voltage of the inverter under test 500 by scanning the barcode on the inverter under test 500, etc., and the test voltage can be determined based on the rated voltage of the inverter under test 500. The test voltage can be equal to the rated voltage, or it can be calculated based on the rated voltage. After the main control unit determines the test voltage of the inverter under test 500, it controls the switching circuit 210 connected to the output terminal of the multi-voltage power supply unit 100 with the corresponding voltage amplitude to be turned on, so as to supply the test voltage to the DC side of the inverter under test 500.

[0048] According to the aging test device for inverters under test of this application, the multi-voltage power supply unit 100 converts the grid voltage 400 into multiple output voltage levels to adapt to inverters under test 500 with different voltage levels. Multi-voltage output is achieved through a single power supply circuit, reducing the number of devices and space occupation. During the aging test of the inverter, the converted AC output is transmitted to the AC input terminal of the rectifier unit 600, where it is rectified before being supplied to the inverter under test 500, realizing the reuse of energy and saving energy.

[0049] Figure 2 illustrates an aging detection device for an inverter under test provided in an embodiment of this application. Referring to Figure 2, in some embodiments, the multi-voltage power supply unit 100 includes: a multi-winding transformer having a primary winding and multiple secondary windings, the primary winding being used for electrical connection to the power grid, and the secondary windings being electrically connected to the first terminal of each switching circuit 210.

[0050] The multi-winding transformer includes a primary winding and multiple secondary windings. The primary winding is directly connected to the power grid 400, responsible for receiving AC power from it. The secondary windings are designed with different turns ratios to output voltages of varying amplitudes. The main control unit controls the conduction of different switching circuits 210 to establish a power transmission path between the output line 220 and specific secondary windings, thereby meeting the input voltage requirements of different inverters under test 500.

[0051] As an example, a multi-winding transformer can convert the grid voltage of 400V into four voltage amplitudes: 220VAC, 380VAC, 480VAC, and 600VAC. After passing through a rectifier unit 600 containing a filter circuit, the corresponding DC-side output voltages of the rectifier unit 600 are approximately VDC, 540VDC, 680VDC, and 850VDC, respectively. After determining the rated voltage of the inverter 500 under test, the main control unit identifies its rated DC input voltage as 540V, thus determining its test voltage to be 380VAC. The main control unit then controls the switching circuit 210 connected to the secondary winding that outputs 380VAC to conduct.

[0052] In some embodiments, an air switch QF1 is also provided between the output line 220 and the rectifier unit 600. When the rectifier unit 600 generates excessive current due to a short circuit or excessive load, the air switch QF1 can detect and cut off the circuit to prevent the rectifier unit 600 from being damaged due to overload.

[0053] In some embodiments, the switching circuit 210 includes a first branch 211 and a first contactor main contact KM1. The first end of the first branch 211 is connected to the output end of the multi-voltage conversion unit 100, and the second end of the first branch 211 is electrically connected to the first end of the output line 220; the first contactor main contact KM1 is disposed in each of the first branches 211; the main control unit includes a plurality of first contactor coils KM1', and the first contactor coils KM1' are correspondingly coupled to the first contactor main contacts KM1.

[0054] Each first branch 211 has its first end connected to a corresponding secondary winding, and each first branch 211 has its second end electrically connected to the first end of the output line 220. A first contactor main contact KM1 is provided on each first branch 211. These contacts act as switches for the power transmission path. When the first contactor main contact KM1 is engaged, the first branch 211 it belongs to is turned on. The secondary winding connected to this first branch 211 can transmit the test voltage to its corresponding rectifier unit 600, and after rectification by the rectifier unit 600, it is transmitted to the inverter under test 500.

[0055] When the main control unit detects that the inverter under test 500 requires a certain voltage level, it energizes the target first contactor coil KM1', causing the corresponding target first contactor main contact KM1 to close. The target first contactor main contact KM1 refers to the first contactor main contact KM1 on the first branch 211 connected to the secondary winding capable of providing the required test voltage to the inverter under test 500. The target first contactor coil KM1' refers to the first contactor coil coupled to the target first contactor main contact KM1. After the target first contactor main contact KM1 closes, the first branch 211 it belongs to will conduct, thereby enabling the inverter under test 500 to obtain the required stable voltage.

[0056] Figures 3 and 4 illustrate the main control unit provided in an embodiment of this application. Referring to Figures 3 and 4, in some embodiments, the main control unit further includes a programmable logic controller (PLC) and multiple second branches. The PLC has multiple output ports; each second branch is connected in parallel, and each second branch includes a relay and a first contactor coil connected in series, with the coil of each relay corresponding to a first output port of the PLC.

[0057] It is understandable that the number of second branch 313 and relay K is the same as the number of first branch 211. Each second branch 313 corresponds to one first branch 211. When a certain second branch 313 is turned on, the first contactor coil KM1' set on the second branch 313 is energized, so that the first contactor main contact KM1 coupled to the energized first contactor coil KM1' can be attracted. That is, when the second branch 313 is turned on, the corresponding first branch 211 is turned on.

[0058] Both relay K and the first contactor coil KM1' are located on the second branch 313. Relay K can open or close its second branch 313 according to the instructions of programmable logic controller 311, thereby controlling the energization state of the first contactor coil KM1'. By controlling the opening and closing of relay K on the second branch 313 to control the opening and closing of the first contactor on the first branch 211, weak current can control strong current, achieving electrical isolation between programmable logic controller 311 and switching unit 200. This isolation effectively reduces the impact of strong current flowing through switching unit 200 on programmable logic controller 311, improving system safety.

[0059] Referring to Figure 4, the output port of the programmable logic controller 311 is connected to the coil of each relay K, and can activate the target output port in response to a drive signal. When the target output port is activated, the target relay coil K' connected to it will receive electrical energy, thereby causing the target relay to operate. The target relay and the target first contactor coil are located on the same second branch 313. Therefore, when the target relay operates, the target first contactor coil is energized, realizing the conduction of the target first branch where the main contact of the target first contactor coil is located.

[0060] As an example, the switching unit 200 includes four first branches 211, the output voltages of the secondary windings connected to the four first branches 211 being 220VAC, 380VAC, 480VAC, and 600VAC, respectively. The main contacts of the first contactors on the four first branches 211 are KM1a, KM1b, KM1c, and KM1d, respectively. The first contactor coils located on the second branch 313 corresponding to each main contactor are KM1a', KM1b', KM1c', and KM1d', respectively. The relays K connected in series with each first contactor coil on the second branch 313 are Ka, Kb, Kc, and Kd, respectively. The relay coils connected to the output port of the programmable logic controller 311 are Ka', Kb', Kc', and Kd', respectively. After reading the nameplate parameters of the inverter under test 500, the main control unit identifies that its DC input voltage is 540V (corresponding to 380VAC on the AC side of the rectifier unit 600). Upon this identification, a drive signal is generated. This drive signal activates the output port of the programmable logic controller 311, which is connected to the relay coil Kb', to output a high-level signal. The target relay coil Kb' is energized, and the target relay b closes. At this time, the target first contactor coil KM1b' is energized, and the main contact KM1b of the target first contactor conducts. That is, the first branch 211, connected to the secondary winding with an output voltage of 380VAC, is activated, and the secondary winding with an output voltage of 380VAC provides power to the inverter under test 500.

[0061] Referring to Figure 3, in some embodiments, the main control unit further includes a third contactor KM3, a power-on button S, a power-on indicator light L, and a fan M. When the power-on button S is pressed, the third contactor coil KM3' is energized, causing the main contacts of the third contactor KM3 to close, and the second control unit 310 is powered. The fan M operates to dissipate heat from the second control unit 310, the power-on indicator light L illuminates, and the programmable logic controller 311 is powered on and operates normally.

[0062] Referring to Figure 4, in some embodiments, the main control unit further includes an interlock circuit 312. The interlock circuit 312 includes a plurality of first contactor auxiliary contacts, which are respectively disposed on each of the second branches 313. The interlock circuit 312 includes a plurality of first contactor auxiliary contacts KM1”, which are respectively disposed on each of the second branches 313. At least one first contactor auxiliary contact KM1” from another second branch 313 is disposed on each of the second branches 313. The first contactor auxiliary contact KM1” is disconnected when the corresponding first contactor main contact KM1 is engaged.

[0063] The interlock circuit 312 is mainly used to force the non-target second branch 313 to be disconnected when the target second branch 313 is turned on, effectively reducing the safety hazards such as current overload and short circuit that may be caused by multiple branches being turned on at the same time, and ensuring the stable operation of the electrical system.

[0064] The first contactor auxiliary contacts KM1” installed on each of the second branches 313 form a cross-interlocking network. When a certain first contactor main contact KM1 is engaged, its corresponding first contactor auxiliary contact KM1” is disengaged, and the second branch 313 with its corresponding first contactor auxiliary contact KM1” is also in an open state. Therefore, the first contactor main contact KM1 on the first branch 211 corresponding to the second branch 313 is disengaged.

[0065] Taking the aforementioned example, the second branch 313, which houses the first contactor coil KM1a', also has a first contactor auxiliary contact KM1b' corresponding to the first contactor main contact KM1b. When the target first contactor coil KM1b' is energized and the target first contactor main contact KM1b is conducting, the first contactor auxiliary contact KM1b' is disconnected, causing the second branch 313 with the first contactor coil KM1a' to disconnect, which in turn disconnects the first branch 211 where the first contactor main contact KM1a is located. This reduces the risk that the first branch 211 where the first contactor main contact KM1a is located will also be conducting when the first branch 211 where the first contactor main contact KM1b is located is conducting.

[0066] In some embodiments, the number of first contactor auxiliary contacts KM1” provided on each second branch 313 is equal to the number of the remaining second branches 313, and each first contactor auxiliary contact KM1” on any second branch 313 comes from a different branch.

[0067] Each second branch 313 is provided with an auxiliary contact KM1” from each of the other second branches 313. When any first contactor coil KM1’ is energized, its corresponding first contactor main contact KM1 is attracted, and the auxiliary contacts of the first contactor main contact KM1 on the other second branches 313 close, causing the other second branches 313 to open, that is, the other first contactor main contacts KM1 are open, thus turning off the other first branches 211. By providing auxiliary contacts from each of the other second branches 313 on each second branch 313, it is possible to ensure that only one first branch 211 is conducting at any given time, reducing the risk of short circuits caused by multiple branches being conducting simultaneously.

[0068] One embodiment of this application provides an inverter aging detection system, including an inverter under test 500 and the aforementioned inverter aging detection device.

[0069] The specific structure and working principle of the inverter aging detection device can be referred to in the aforementioned embodiments, and will not be repeated here.

[0070] According to the inverter aging test system of this application, the multi-voltage power supply unit 100 converts the grid voltage 400 into multiple levels of output voltage to adapt to the inverter under test 500 with different voltage levels. Multi-voltage output is achieved through a single power supply circuit, reducing the number of devices and space occupation. During the aging test of the inverter, the converted AC output is transmitted to the AC input terminal of the rectifier unit 600, where it is rectified before being supplied to the inverter under test 500, realizing the reuse of energy and saving energy.

[0071] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An inverter aging detection device, characterized in that, include: A multi-voltage power supply unit (100) has multiple output terminals and is configured to provide output voltages of different amplitudes through each of the output terminals; The switching unit (200) includes multiple switching circuits (210) and at least one output line (220). The first terminal of each switching circuit (210) is electrically connected to each output terminal of the multi-voltage conversion unit (100). The second terminal of each switching circuit (210) is connected in parallel with each other and electrically connected to the first terminal of the output line (220). The second terminal of the output line (220) is used to connect to the AC output terminal of the inverter under test. At least one rectifier unit (600) is included. The AC input terminal of the rectifier unit (600) is used to connect to the AC output terminal of the inverter under test (500), and the DC output terminal of the rectifier unit (600) is used to connect to the DC input terminal of the inverter under test (500).

2. The inverter aging detection device according to claim 1, characterized in that, The switching circuit includes: a first branch (211), the first end of which is connected to the output end of the multi-voltage conversion unit, and the second end of which is electrically connected to the first end of the output line; a first contactor main contact (KM1) disposed in the first branch (211); the inverter aging detection device further includes: a main control unit, including multiple first contactor coils (KM1'), the first contactor coils (KM1') being coupled to the first contactor main contact (KM1).

3. The inverter aging detection device according to claim 2, characterized in that, The main control unit further includes: a programmable logic controller (311) with multiple output ports; multiple second branches (313), each second branch (313) is connected in parallel with each other, and each second branch (313) includes a relay (K) and the first contactor coil (KM1') connected in series, and the coil (K') of each relay is respectively connected to the output port of the programmable logic controller (311).

4. The inverter aging detection device according to claim 3, characterized in that, The main control unit further includes an interlock circuit (312), which includes a plurality of first contactor auxiliary contacts (KM1”), the first contactor auxiliary contacts (KM1”) are respectively disposed on each of the second branches (313), and each second branch (313) is provided with at least one first contactor auxiliary contact (KM1”) from another second branch (313), the first contactor auxiliary contact (KM1”) is disconnected when the corresponding first contactor main contact (KM1) is engaged.

5. The inverter aging detection device according to claim 4, characterized in that, The number of first contactor auxiliary contacts (KM1”) provided on each of the second branches (313) is equal to the number of the remaining second branches (313), and each of the first contactor auxiliary contacts (KM1”) on any second branch (313) comes from a different branch.

6. The inverter aging detection device according to any one of claims 1-5, characterized in that, The multi-voltage power supply unit (100) includes: a multi-winding transformer having a primary winding and multiple secondary windings, wherein the primary winding is used for electrical connection to the power grid and the secondary windings are electrically connected to the first terminal of each of the switching circuits (210).

7. An inverter aging detection system, characterized in that, It includes at least one inverter aging detection device according to any one of claims 1-6 and an inverter under test, wherein the inverter under test is electrically connected to the inverter aging detection device.

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