Test method for solid state transformer

Abstract

The present invention relates to a test method for a semiconductor transformer, comprising the steps of charging a DC voltage to the DC side of a semiconductor transformer module and applying AC power to the AC side in a control unit, and controlling a power converter connected between the DC side of the semiconductor transformer module and the grid in the control unit to perform no-load and load tests on the semiconductor transformer module, wherein if there is an abnormality in a parameter detected during the test, the test may be stopped and an error log may be collected.

Description

Technology Field

[0001] The present invention relates to a test method for a semiconductor transformer, and more specifically, to a test method capable of testing the integrity of a semiconductor transformer. Background Technology

[0002] In general, solid-state transformers (SSTs) are one of the cutting-edge topics in power electronics applications and feature bidirectional conversion between AC and DC power.

[0003] SST is connected to medium voltage (MV) levels, whereas conventional power electronics applications use low voltage (LV) levels. Additionally, SST is characterized by being electrically isolated using medium frequency (MF) or high frequency (HF) transformers.

[0004] In addition, SST differs from conventional power transformers in that it can provide various functions through control flexibility.

[0005] Transformers need to be tested for performance, and Korean Patent Registration No. 10-2654141 (registered on March 29, 2024, Transformer Characteristic Test Apparatus and Method) describes a test method for a general winding transformer.

[0006] Specifically, the method includes a step in which an iron loss test unit detects the secondary side voltage and secondary side current of the transformer to test the iron loss of the transformer, a step in which a copper loss test unit detects the primary side and secondary side voltage and current of the transformer, respectively, to test the copper loss of the transformer, a step in which a resistance temperature test unit detects the primary side and secondary side voltage and current of the transformer, respectively, and detects the resistance and temperature of the primary winding and secondary winding of the transformer, and an analysis unit analyzes the characteristics of the transformer based on the measurements of the iron loss test unit, the copper loss test unit, and the resistance temperature test unit. In the step in which the iron loss test unit detects the secondary side voltage and current of the transformer to test the iron loss of the transformer, the iron loss test unit adjusts the secondary side voltage of the transformer within a preset voltage setting range and describes a method for measuring the secondary side voltage and secondary side current of the transformer.

[0007] However, such conventional transformer characteristic testing methods cannot be applied to the testing of semiconductor transformers.

[0008] Semiconductor transformers do not use windings, iron cores, etc., and therefore, there is a demand in the current market for the development of methods to test semiconductor transformers. The problem to be solved

[0010] The problem that the present invention aims to solve, taking into account the problems of the conventional technology described above, is to provide a test method capable of testing the performance of a semiconductor transformer.

[0011] Specifically, the present invention aims to provide a test method capable of testing the performance of a semiconductor transformer unit module by applying a power feedback method. means of solving the problem

[0012] A test method for a semiconductor transformer according to a preferred embodiment of the present invention includes the steps of charging a DC voltage to the DC side of a semiconductor transformer module and applying AC power to the AC side in a control unit, and controlling a power converter connected between the DC side of the semiconductor transformer module and the grid in the control unit to perform no-load and load tests on the semiconductor transformer module, wherein if there is an abnormality in a parameter detected during the test, the test may be stopped and an error log may be collected.

[0013] In an embodiment of the present invention, step a) may include a-1) a step of pre-charging the DC side of the semiconductor transformer module, a-2) a step of performing DC link charging within the semiconductor transformer module with the pre-charged voltage, and a-3) a step of supplying an AC voltage to the AC side of the semiconductor transformer module using a high-voltage transformer.

[0014] In an embodiment of the present invention, after step a-3), a step of stopping precharging may be further included.

[0015] In an embodiment of the present invention, the pre-charging voltage, DC link charging voltage, and AC voltage are detected in each of steps a-1), a-2), and a-3), and the next step can be performed only if the detected voltage is within a reference range.

[0016] In an embodiment of the present invention, if the detected voltage deviates from a reference range, the control unit may further include the step of collecting an error log.

[0017] In an embodiment of the present invention, step b) may include b-1) a step of checking the settings of the power converter in the control unit and performing a load test using the power converter, and b-1) a step of performing the load test, wherein a forward load test and a reverse load test are performed.

[0018] In an embodiment of the present invention, the forward load test is a power direction test from the semiconductor transformer module to the grid based on the power converter, and the reverse load test may be a power direction test from the grid to the semiconductor transformer module based on the power converter. Effects of the invention

[0020] The present invention has the effect of ensuring the reliability and stability of semiconductor transformers by applying a power feedback method to test the performance of semiconductor transformer unit modules, thereby identifying malfunctions and defects before manufacturing semiconductor transformers. Brief explanation of the drawing

[0022] FIG. 1 is a flowchart of a semiconductor transformer test method according to a preferred embodiment of the present invention. FIG. 2 is an exemplary diagram of a device for the application of the present invention. Figure 3 is a block diagram of the control unit in Figure 2. Figure 4 is an example of a semiconductor transformer module. FIG. 5 is a flowchart of the error log collection method of the present invention. Specific details for implementing the invention

[0023] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention are described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various modifications can be made. The description of the embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. In the attached drawings, components are depicted with their sizes enlarged compared to their actual size for convenience of explanation, and the proportions of each component may be exaggerated or reduced.

[0024] Terms such as 'first' and 'second' may be used to describe various components, but said components should not be limited by said terms. These terms may be used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, 'first component' may be named 'second component,' and similarly, 'second component' may be named 'first component.' Furthermore, singular expressions include plural expressions unless the context clearly indicates otherwise. Unless otherwise defined, terms used in the embodiments of the present invention may be interpreted in the sense commonly known to those skilled in the art.

[0025] Hereinafter, a test method for a semiconductor transformer according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0027] FIG. 1 is a flowchart of a semiconductor transformer test method according to a preferred embodiment of the present invention.

[0028] Referring to FIG. 1, the present invention includes a voltage supply step (S10) for testing and a no-load and load test step (S20) using a power converter.

[0029] The voltage supply step (S10) includes a step of checking parameters of a semiconductor transformer module to be tested (S11), a step of pre-charging the semiconductor transformer module (S12), a step of checking the pre-charged voltage (S13), a step of charging the DC link when the pre-charging voltage is normal (S14), a step of supplying an AC high voltage (S15), a step of operating the semiconductor transformer module to be tested (S16), and a step of stopping pre-charging (S17).

[0030] The no-load and load test step (S20) includes a step of checking the communication status and settings of the power converter (S21), a step of executing a no-load test (S22), a step of executing a forward load test (S23), and a step of executing a reverse load test (S24).

[0031] Hereinafter, the configuration and operation of a preferred embodiment of the semiconductor transformer test method of the present invention configured as described above will be explained in more detail.

[0032] FIG. 2 is an exemplary diagram of a test apparatus to which a semiconductor transformer test method according to a preferred embodiment of the present invention is applied, and FIG. 3 is an exemplary diagram of an exemplary configuration of a control unit.

[0033] Referring to FIG. 2 and FIG. 3 respectively, the present invention can be applied to the operation of the following test device.

[0034] A device can be implemented comprising: a power converter (PCS, 20) connecting the DC side of a semiconductor transformer module (10) to be tested to a grid (GRID, 1); a precharger (30) pre-charging the DC side of the semiconductor transformer module (10); a high-voltage transformer (40) providing AC high voltage to the AC side of the semiconductor transformer module (10); a first circuit breaker (61) between the power converter (20) and the grid (1); a second circuit breaker (62) between the high-voltage transformer (40) and the grid (1); a third circuit breaker (63) between the high-voltage transformer (40) and the semiconductor transformer module (10); and a control unit (50) that detects the state of the semiconductor transformer module (10) and controls the state of the first to third circuit breakers (61, 62, 63).

[0035] The control unit (50) is configured to include a user interface (51), an interface (52) for insulation, and a circuit breaker driving unit (53) for driving the first to third circuit breakers (61 to 63).

[0036] The user interface (51) may be a graphical user interface (GUI) and supports interaction with the test device of the present invention. That is, the user interface (51) visually displays parameter information of the semiconductor transformer module (10) that is the subject of the test and allows checking voltage information of a specific node, etc.

[0037] The interface (52) isolates the test area and the user area, thereby preventing the occurrence of safety accidents.

[0038] The circuit breaker driving unit (53) controls the state of the first circuit breaker (61), the second circuit breaker (62), and the third circuit breaker (63) according to the input of the user interface (51).

[0039] A semiconductor transformer is used by connecting a plurality of semiconductor transformer modules (10) in series according to the magnitude of the input voltage. Before manufacturing the semiconductor transformer, the present invention tests the performance of the semiconductor transformer modules (10) constituting the semiconductor transformer.

[0040] An example of the configuration of a semiconductor transformer module (10) is shown in FIG. 4.

[0041] The semiconductor transformer module (10) includes a Dual Active Bridge (DAB) converter (11) and an Active Front End (AFE) rectifier (12), and includes DC link capacitors (C1, C2) positioned between the DAB converter (11) and the AFE rectifier (12).

[0042] In addition, it includes a capacitor (C3) on the input side of the DAB converter (11).

[0043] The characteristics of this composition will be discussed in more detail in the following explanation.

[0044] The power converter (PCS Power Conversion System, 20) can convert commercial power from the grid (1) into a power form desired by the user and control the flow of power.

[0045] The power converter (20) can convert various types of power, including AC to DC and DC to AC, and can control the direction of power flow according to the control of the control unit (50).

[0046] First, as in step S10, the status and setting parameters of the components of the test device are checked, and power is supplied to the DC side and AC side of the semiconductor transformer module (10) that is the subject of the test.

[0047] Specifically, the communication status between the control unit (50) and the semiconductor transformer module (10) is checked as in step S11.

[0048] The DAB converter (11) and AFE rectifier (12) of the semiconductor transformer module (10) each include sensors and a means to transmit the detection results of the sensors to the outside.

[0049] For example, CAN (Controller Area Network) communication and optic SPI (Serial Peripheral Interface) can be used for communication between processors.

[0050] First, check whether a normal communication connection has been established, and collect and verify various parameters including current and voltage of the semiconductor transformer module (10).

[0051] Next, as in step S12, the control unit (50) operates the precharger (30) and increases the DC side voltage of the semiconductor transformer module (10) to a reference range.

[0052] For example, it can be stepped up to 750VDC.

[0053] Next, in step S13, it is checked whether the DC side voltage of the semiconductor transformer module (10) has been boosted to the reference range (750VDC).

[0054] In the present invention, each step can be defined as performing the next step only when a condition is satisfied.

[0055] FIG. 5 is a flowchart of the processing sequence of the present invention for proceeding to the next step.

[0056] Referring to FIG. 5, the present invention may include a step (S31) of determining whether the result detected in a previous step, such as steps S12 and S13, is within a reference range.

[0057] Such a judgment is made by the control unit (50), and the next step can be performed only when it is within the standard range.

[0058] If it is outside the standard range, the power converter, etc. is turned off (S32), the first to third circuit breakers (61, 62, 63) are controlled to be open (S33), and an error log is collected (S33).

[0059] The error log may indicate an error in a value detected during the execution of a specific step.

[0060] Next, if it is confirmed that the voltage has been boosted to the reference range in step S13, the DC link capacitors (C1, C2) are charged as in step S14, and it is checked whether charging has been performed.

[0061] Charging of the DC link is performed by operating the DAB converter (11) in the control unit (50). The capacitors (C1, C2) are charged with a voltage of 1600VDC, and it is checked whether the voltage is maintained for a certain period of time.

[0062] Through this process, it is possible to verify the switch burnout of the DAB converter (11).

[0063] When it is determined that the charging of the DC link is complete, the control unit (50) controls the second circuit breaker (62) and the third circuit breaker (63) to be closed through the circuit breaker driving unit (53) as in step S15, and supplies an AC voltage to the AC side of the semiconductor transformer module (10) through the high-voltage transformer (40). At this time, the AC voltage may be 1000VAC.

[0064] For safety when using the high-voltage transformer (40), it is preferable to place a second circuit breaker (62) and a third circuit breaker (63) at each end of the high-voltage transformer (40).

[0065] After confirming that the AC voltage is being supplied, the semiconductor transformer module (10) is operated as in step S16, and the operation of the precharger (30) is stopped as in step S17.

[0066] Through each of these steps, a DC voltage and an AC voltage set at both ends of the semiconductor transformer module (10) are applied.

[0067] The control unit (50) of the present invention tests the semiconductor transformer module (10) as in step S20.

[0068] To do this, communication with the power converter (20) is checked as in step S21, and parameters are verified.

[0069] The parameters at this time are determined by checking various setting values ​​of the power converter (20).

[0070] If it is determined that the result is normal, the control unit (50) operates the power converter (20) as in step S22 to perform a no-load test.

[0071] The operation of the power converter (20) can perform a no-load test. That is, the no-load test of the semiconductor transformer module (10) is controlled in conjunction with the AFE rectifier (12) in an open state, and the normality of the rated voltage can be checked.

[0072] In normal cases, a load test is performed. The load test can be performed in both directions depending on the characteristics of the semiconductor transformer module (10). At this time, the first circuit breaker (61) can be closed using the circuit breaker driving unit (53).

[0073] Although it is stated that Step S23 performs a forward load test and Step S24 performs a reverse load test, the order may be changed.

[0074] Forward power conversion is defined in the present invention as power being formed in a direction toward the grid (1) through the semiconductor transformer module (10) and the power converter (20), and reverse power conversion is defined as power from the grid (1) being supplied to the semiconductor transformer module (10) through the power converter (20) in the opposite direction.

[0075] This is achieved by controlling the flow of power by controlling such a directional power converter (20).

[0076] In step S23, the power flow direction of the power converter (20) is first set to the grid (1) side in the control unit (50) so that power is supplied to the grid (1).

[0077] That is, the AC-DC conversion state of the semiconductor transformer module (10) is created, and at this time, the parameters of the semiconductor transformer module (10) are collected by the control unit (50) to check whether it is normal.

[0078] If determined to be normal, perform the reverse load test of step S24.

[0079] The control unit (50) controls the power flow direction of the power converter (20) from the grid (1) toward the semiconductor transformer module (10) and detects the characteristics of the semiconductor transformer module (10).

[0080] That is, a DC-AC conversion state of the semiconductor transformer module (10) is created, and at this time, parameters of the semiconductor transformer module (10) can be collected to check whether it is normal.

[0081] If it is determined that there is an abnormality during the load test phase, the system can be turned off for safety, and the first to third circuit breakers (61 to 63) can be turned off, and the error log of the semiconductor transformer module (10) can be collected.

[0082] In this way, the present invention enables the performance of no-load test, forward load test, and reverse load test of a semiconductor transformer module (10) constituting a semiconductor transformer.

[0084] Although embodiments according to the present invention have been described above, they are merely illustrative and those skilled in the art will understand that various modifications and equivalent embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the following claims. Explanation of the symbols

[0085] 10: Semiconductor transformer module 11: DAB converter 12: AFE Rectifier 20: Power Converter 30: Precharger 40: High-voltage transformer 50: Control unit 51: User interface 52: Interface 53: Circuit breaker drive unit 61: 1st circuit breaker 62: 2nd circuit breaker 63: Third circuit breaker

Claims

Claim 1 a) a step of charging a DC voltage to the DC side of a semiconductor transformer module and applying AC power to the AC side in the control unit; and b) a step of controlling a power converter connected between the DC side of the semiconductor transformer module and the grid in the control unit to perform no-load and load tests on the semiconductor transformer module, wherein if there is an abnormality in a parameter detected during the test, the test is stopped and an error log is collected. Claim 2 A method for testing a semiconductor transformer according to claim 1, wherein step a) comprises: a-1) a step of pre-charging the DC side of the semiconductor transformer module; a-2) a step of performing DC link charging within the semiconductor transformer module with the pre-charged voltage; and a-3) a step of supplying an AC voltage to the AC side of the semiconductor transformer module using a high-voltage transformer. Claim 3 A test method for a semiconductor transformer according to paragraph 2, further comprising a step of stopping precharging after step a-3) above. Claim 4 A test method for a semiconductor transformer according to claim 2, characterized in that, in each of the steps a-1), a-2), and a-3), the pre-charging voltage, DC link charging voltage, and AC voltage are detected, and the next step is performed only if the detected voltage is within a reference range. Claim 5 A test method for a semiconductor transformer according to claim 4, further comprising the step of collecting an error log in the control unit when the detected voltage deviates from a reference range. Claim 6 A method for testing a semiconductor transformer according to claim 1, wherein step b) comprises: b-1) a step of checking the settings of the power converter in the control unit and performing a load test using the power converter; and b-1) a step of performing the load test, wherein a forward load test and a reverse load test are performed. Claim 7 A test method for a semiconductor transformer according to claim 6, characterized in that the forward load test is a power direction test from the semiconductor transformer module to the grid based on the power converter, and the reverse load test is a power direction test from the grid to the semiconductor transformer module based on the power converter.

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