High current source and testing system for power equipment testing

Abstract

A high-current source (200) for a test system of an electrical device (30) includes: a first group of multiple first switchable half-bridges (212) and a second group of multiple second switchable half-bridges (222), wherein the first and second switchable half-bridges are connected in parallel and are used to redundantly divide the test current. A control unit (280) controls the first and second switchable half-bridges (212, 222) according to an input signal, such that an output signal of the test current corresponding to the input signal is applied to a bridging branch (230) between the first switchable half-bridge (212) and the second switchable half-bridge (222).

Description

Technical Field

[0001] This invention belongs to the field of high current measurement technology, and particularly relates to a high current source for a test system for testing electrical energy devices and a test system having such a high current source. Background Technology

[0002] In power supply networks, electrical devices such as power transformers or switchgear are frequently used to convert and distribute electrical energy. In addition, this scenario also commonly uses high-voltage or high-current instrument transformers for measuring voltage and current within the power grid, circuit breakers such as primary and secondary relays for power distribution or as components of protection systems, and other electrical devices such as generators. These electrical devices, or other electrical devices such as electric motors, are also used in industrial sectors, particularly in manufacturing.

[0003] For the commissioning or maintenance of facilities containing such electrical energy devices, it may be necessary to check their functionality and characteristics. This can be done, for example, by measuring resistance with a test current to check the electrical contact, switching characteristics, or conductivity of electrical energy devices such as circuit breakers, transformers with any tap changers, grounding devices, or rotating machinery such as generators or electric motors. It can also be done, for example, by measuring the transformation ratio of electrical energy devices such as power transformers or current transformers with a test current. Since these functions and characteristics can change due to factors such as aging, damage during transportation, manufacturing defects, short circuits, or magnetization of the (transformer) cells, such measurements are particularly important, and correspondingly, regular monitoring may be necessary to ensure the operational reliability of the electrical energy devices and the corresponding high-voltage equipment.

[0004] Such tests are typically conducted in field use, i.e., in outdoor or industrial environments. In this case, the equipment used should be lightweight, especially for field use, and should be robust and durable enough to be transported to the appropriate location. Summary of the Invention

[0005] Therefore, there is a need to improve the testing of the functionality and characteristics of electrical devices using test current, and in particular, there is a need to manufacture high current sources for this purpose, as well as more robust, durable, transportable, reliable, or safer testing systems.

[0006] The present invention satisfies each of the above-mentioned requirements through a high-current source for a test system for testing electrical devices as claimed in claim 1, a test system for testing electrical devices with test current as claimed in claim 15, and the use of such a high-current source or such test system for testing electrical devices with test current as claimed in claim 16. The dependent claims relate to advantageous embodiments of the invention.

[0007] A first aspect of the present invention relates to a high-current source for a test system used for testing electrical devices. The high-current source has a first group of multiple first switchable half-bridges connected in parallel, with the number of these half-bridges redundantly dividing the test current. Furthermore, the high-current source has a second group of multiple second switchable half-bridges connected in parallel, with the number of these second switchable half-bridges also redundantly dividing the test current.

[0008] The control unit of the high current source is used to control the first group of multiple first switchable half-bridges and the second group of multiple second switchable half-bridges according to the input signal, so that the output signal of the test current exists on the bridging branch between the first switchable half-bridge and the second switchable half-bridge, and the output signal corresponds to the input signal.

[0009] One advantage of this high current source and the associated maximum current (approximately 500A or even in the kA range) that can be generated as the test current is that the electrical device can be tested with a test current that corresponds to or is at least higher than the rated operating current of the electrical device, at least substantially corresponding to the functions and characteristics of the electrical device during operation.

[0010] One advantage of redundancy in dividing the test current is that the test current can still be generated even if individual switchable half-bridges fail. This means that the test can be performed more reliably and the robustness of the high-current source can be improved. Test equipment such as high-current sources may be subjected to mechanical loads, such as during transportation, or thermal loads, due to the large test currents, which could cause individual half-bridges to fail. Therefore, the aforementioned redundancy can extend the service life of the high-current source.

[0011] By dividing the test current, the thermal and / or electrical loads of the high-current source components, especially the switchable half-bridge, can be reduced, thereby improving the reliability of the high-current source, reducing its failure, and / or enabling better testing with larger currents or shorter waiting times (e.g., waiting for cooling).

[0012] By generating the test current on the bridging branch, a larger voltage amplitude can be achieved at the preset operating voltage of the high current source, thereby enabling a larger (maximum) current and improving operational reliability. This is particularly true because, by employing a symmetrical operating voltage, the voltage amplitudes of the first and second switchable half-bridge sides relative to ground potential, as required by other aspects, are only about half.

[0013] Especially for cases where the test current is generated via a high-current transformer, one particular advantage of generating the test current using the first set of multiple switchable half-bridges and the second set of multiple switchable half-bridges is the reduction in weight. This specifically means that the high-current source or the test system containing the high-current source is lighter, thus making it easier to transport. This may be particularly advantageous not only for field applications but also for applications in other locations. Accordingly, some variations of the high-current source can weigh well below 10 kg.

[0014] For the purposes of this invention, "high current source" should be understood to mean at least one current source for providing a high current, i.e., a current with a maximum value of at least 500A. In principle, such high current sources can also provide smaller currents, for example, depending on their driving method. Such high current sources can also have different test current ranges that can be selected manually or automatically. For the purposes of this invention, "high current source" can also be understood to mean that the high current source is designed in the form of a structural unit. In this case, the high current source can be constructed as a high current module, for example, as an expansion module of a test system. Such expansion modules can be accommodated within module slots of the main equipment of the test system.

[0015] For the purposes of this invention, "high current" should be understood to specifically refer to a current of at least 500A. In the case of alternating current, this value may be related to the amplitude or effective value of the alternating current. In the case of direct current, this value may be related to the direct current component, or to the peak value or effective value that is the largest in absolute terms.

[0016] For the purposes of this invention, "high voltage" should be understood to specifically mean a voltage of at least 1000V. In the case of AC voltage, this value may be related to the amplitude or effective value of the AC voltage. In the case of DC voltage, this value may be related to the DC voltage component, or to the peak value or effective value that is the largest in absolute value.

[0017] For the purposes of this invention, "electrical device" should be understood to mean, for example, a device as part of a high-voltage energy supply system or as part of an electrically operated manufacturing apparatus, which operates under high voltage or high current for control, conversion, or measurement, or may be exposed to high current for some other reason, and therefore should be configured for safe operation, for example by providing sufficiently high conductivity. An electrical device may also be exposed to high voltage for some other reason, and therefore should be configured for safe operation, for example by providing sufficiently high electrical insulation. An electrical device that can be exposed to high voltage and configured for this purpose may also be called "high-voltage equipment". Such electrical devices can be particularly power transformers, (high-voltage) switchgear, (high-voltage) safety switches, circuit breakers such as primary or secondary relays, grounding devices, rotating machinery operating under or generating high voltage such as motors or generators, transformer tap changers, instrument transformers such as high-voltage or high-current transformers (e.g., inductive current transformers with transformer cores or Rogowski coils, or non-inductive current transformers using field plates, Faraday effects, etc.), or some other current transformers or voltage transformers. Such electrical devices can also be particularly used for other electrical equipment that measures large currents. Such electrical devices can also perform micro-ohmic measurements, particularly by measuring the large current from the high current source and the voltage generated during the process.

[0018] According to some embodiments, each of the first switchable half-bridges has two controllable switching elements connected in series by a connection point. Each of the second switchable half-bridges also has two controllable switching elements connected in series by a connection point. The connection points of the first switchable half-bridges are connected in parallel and electrically connected to a first side of the bridging branch. The connection points of the second switchable half-bridges are also connected in parallel and electrically connected to a second side of the bridging branch. Finally, the control unit is used to control or drive the controllable switching elements.

[0019] An advantage of the bridging branch located between the first and second switchable half-bridges and for the output signal is, for example, that it can be advantageously combined with embodiments in which each of the first and second switchable half-bridges has two controllable switching elements, and in particular, that the high current source does not require an energy supply device with a center tap.

[0020] In some embodiments where the connection points of the first and second switchable half-bridges are electrically connected to the first or second side of the bridging branch via filtering elements, the following advantages are particularly noticeable: the individual switchable half-bridges can be decoupled, for example, in terms of their switching behavior, thereby improving the synchronous and therefore particularly simple driving method of the first and second switchable half-bridges in some variations, or improving the asynchronous driving of the first and second switchable half-bridges in other variations. In other embodiments, synchronous or asynchronous driving can also be implemented without such filtering elements. In some variations with or without filtering elements and with asynchronous driving, the control unit is used to drive the switchable half-bridges in a time-biased manner, for example, at preset time intervals or randomly distributed. In some variations with or without filtering elements, the control unit is used to drive in an asynchronous and / or random manner.

[0021] In some embodiments, each of the switchable half-bridges has a non-synchronous hysteresis coil current regulator, particularly in combination with an LC filter. This advantageous approach allows for the regulation of the corresponding current flowing through each half-bridge in a self-oscillating manner.

[0022] In particular, for the case of generating test current through a high current transformer, an advantage of generating the test current through the first group of multiple and the second group of multiple switchable half-bridges is that, under the action of the multiple switchable half-bridges, the situation of all half-bridges synchronizing clock holes / switching cannot occur.

[0023] For example, one advantage of switching each half-bridge in a (random) biased manner by random or asynchronous driving or corresponding adjustment (e.g., by using hysteresis coil current adjustment) is that it can reduce the current ripple or voltage ripple in the output signal, that is, especially reduce the current ripple or voltage ripple in the test current.

[0024] Some embodiments of the energy supply device for receiving electrical energy and for providing positive and negative power supply voltages that are electrically isolated therefrom and supply power to the switchable half-bridge may have particular advantages in that they can improve operational reliability and / or robustness, for example, in terms of scattered interference or interference caused by the switching of the switchable half-bridge.

[0025] In some implementations, operational reliability can be improved by electrically isolating the input signal from the switchable half-bridge, wherein, specifically, in some variations, the output signal is electrically isolated from the input signal.

[0026] According to some implementations, the first group of multiple first switchable half-bridges and the second group of multiple switchable half-bridges are used to generate a large current of at least 500A or even in the kA range as the test current.

[0027] According to some implementations, the number of first switchable half-bridges is equal to the number of second switchable half-bridges, thereby particularly advantageously achieving a symmetrical structure.

[0028] According to some embodiments, the first and / or second groups each include a large number of first and second switchable half-bridges. In some variations, the switchable half-bridges can be discrete components or composed of discrete components. In some embodiments, all the first and / or second switchable half-bridges are also used to generate a maximum current of at least 3A or at most 200A and to conduct the current in the on-state. This advantageous approach allows for further partitioning of electrical and / or thermal loads, meaning that the load on individual components, especially discrete components, can be reduced to only a small fraction of the total load. Variations with more first and / or second switchable half-bridges, such as 20, 40, or more first switchable half-bridges and / or 20, 40, or more second switchable half-bridges, are even more advantageous, especially for larger test currents. The advantage of combining this redundant partitioning approach is particularly significant for field applications, improving fault tolerance and / or robustness.

[0029] A second aspect of the invention relates to a test system for testing an electrical device using a test current. The test system has a portable main device comprising: a housing having a module slot for accommodating and connecting an expansion module; and a connection device disposed on the housing for connecting a portable auxiliary device. The test system also includes a high-current source according to a first aspect of the invention, serving as the expansion module. Furthermore, the high-current source has a housing for the module slot and an energy supply connection device, an input connection device, and first and second high-current connectors disposed on the housing. The portable main device further comprises: a measuring device for measuring a variable under test; and a control device for controlling the measuring device and the high-current source for testing the electrical device. The portable main device controls the high-current source via the input connection device and supplies energy to the high-current source via the energy supply connection device when the high-current source is accommodated in the module slot. The high-current source is configured and controlled by the control device to generate an output signal between the first and second high-current connectors, thereby providing the test current.

[0030] The possible advantages, implementation methods, extensions or modifications mentioned above in relation to the first aspect of the present invention are also applicable to the testing system of the present invention.

[0031] The module slot having a receiving cylinder for the high current source, or some embodiments thereof, may have the particular advantage that the external dimensions of the portable main device or the external dimensions of the portable main device housing are at least substantially unaffected by the receiving or removal of the high current source, thereby simplifying its operation.

[0032] A third aspect of the present invention relates to the use of a device for testing electrical energy with a test current according to a high-current source according to the first aspect of the present invention or a test system according to the second aspect of the present invention. The high-current source or the high-current source of the test system is used to generate the test current. Furthermore, in the test, at least one variable to be measured, generated based on the test current, is measured, preferably by the measuring device of the high-current source or the test system.

[0033] The possible advantages, implementation methods, extensions or modifications mentioned above in relation to the foregoing aspects of the present invention are also applicable to the uses of the present invention.

[0034] Other advantages, features, and application possibilities will become apparent from the following detailed description and / or from the accompanying drawings. Attached Figure Description

[0035] The invention will now be described in further detail with reference to advantageous exemplary embodiments and the accompanying drawings. In these exemplary embodiments, the same elements or components are identified substantially by the same reference numerals, unless the description herein contradicts it, or unless the contradiction is obvious from the context.

[0036] The attached diagrams are all schematic diagrams, in which:

[0037] Figure 1 The image shows a high-current source according to one embodiment;

[0038] Figure 2 The image shows a test system according to one embodiment;

[0039] Figure 3 The diagram shown is a flowchart of the use of a high current source or test system according to one embodiment. Detailed Implementation

[0040] Figure 1 The image shows a high-current source 200 of a test system for testing electrical devices according to an embodiment of the present invention.

[0041] In one exemplary embodiment, the high-current source 200 includes a first set of multiple 210 first switchable half-bridges 212, a second set of multiple 220 second switchable half-bridges 222, a positive power rail 242, a negative power rail 246, and a control unit 280. The control unit 280 is configured to control or drive the first set of multiple 210 and the second set of multiple 220 half-bridges according to an input signal, such that a test current output signal on the bridging branch 230 between the first and second switchable half-bridges corresponds to the input signal.

[0042] Furthermore, some variations of the high-current source 200 have an energy supply device 240 electrically connected to the positive and negative power rails 242, 246, and for providing positive and negative power supply voltages through the power rails to first and second sets of multiple switchable half-bridges 210, 220, respectively. In other variations, the positive and negative power rails 242, 246 may form external contacts and accept the supplied power voltage.

[0043] One of the first switchable half-bridges 212 in the first group of multiple 210 is further shown in detail. Figure 1 As shown in the figure, each first switchable half-bridge has two field-effect transistors 216 and 217, such as MOSFETs, connected in series at connection point 218. For each first switchable half-bridge, the field-effect transistors 216 and 217 form a controllable switching element 216 electrically connected to the positive power rail 242 and another controllable switching element 217 electrically connected to the negative power rail 246. Some variations may also have other controllable switching elements besides field-effect transistors, such as bipolar transistors.

[0044] The connection points 218 of the first switchable half-bridge 212 are connected in parallel and electrically connected to the first side 231 of the bridging branch 230. In some variations, the connection points 218 can be directly electrically connected to each other, or connected to the first side 231 via the filter elements 213 of the corresponding first half-bridges 210 and 212. In some variations, the filter element 213 has an LC filter, or is composed of an LC filter.

[0045] Furthermore, in some variations, the high-current source 200 has a shared first filter element and / or first current sensor device 281 to filter or acquire the current on the first side 231 of the bridging branch 230, thereby advantageously reducing interference emitted due to the switching of controllable switching elements and enabling the determination of the actual test current, for example, for testing or feedback loop purposes. Furthermore, in some variations, the first current sensor device 281 has multiple current sensors and is used to acquire the current on the first side 231 of the bridging branch 230, which is the sum of the currents flowing through each current sensor. For this purpose, in some variations, the current sensors are connected in parallel. Alternatively, in some variations, each current sensor is assigned to one or more half-bridges such that each one acquires the current flowing out of or to the first side 231 of the corresponding half-bridge. This advantageous approach improves current acquisition accuracy and / or reduces weight compared to a current sensor device that acquires a correspondingly larger current with a single current sensor.

[0046] Furthermore, in some variations, each first switchable half-bridge 210 has an adjustment element 214 for regulating the switching of controllable switching elements 216, 217 via a hysteresis coil current regulator, which is in particular a self-oscillating regulator that is not synchronized with the corresponding other adjustment elements 214, and is based, for example, on a signal from the coil of filter element 213, particularly the aforementioned LC filter coil.

[0047] The above description also applies to the second group of multiple 220 second switchable half-bridges, wherein one of these second switchable half-bridges 222 is further shown in detail. Figure 1 Furthermore, each of these second switchable half-bridges has two field-effect transistors (or, more generally, controllable switching elements) 226, 227 connected in series between the positive power rail 242 and the negative power rail 246 via connection point 228. Similarly, the high-current source 200 may also have a shared second filter element and / or second current sensor device 282 corresponding to the second side 232 of the bridging branch 230 electrically connected to connection point 228. Each second half-bridge 220 may also have an adjustment element 224 and / or a filter element 223 for electrically connecting to the second side 232 via the adjustment element 224 and / or the filter element 223.

[0048] Figure 1The first group of multiple 210s and the second group of multiple 220s shown represent a total of seven first switchable half-bridges and a total of seven second switchable half-bridges, respectively. In other variations, the number of first and second switchable half-bridges can be even greater, for example, advantageously greater than or equal to ten, twenty, forty, or forty-eight. This allows for (or even) further subdivision of the resulting test current, thereby reducing the probability of simultaneous half-bridge switching and thus reducing current or voltage ripple, and / or allowing the resulting test current to continue increasing to a preset maximum current even in the event of individual half-bridge failure.

[0049] In some variations of the first and second groups of multiple 210, 220 half-bridges used to generate a maximum current of at least 1 kA as the test current, the maximum current of each half-bridge is designed to be approximately equal to or exactly equal to 25 A, and the number of the first and second switchable half-bridges is forty (or forty-eight for further redundancy). Thus, the provided test current is divided among forty 25 A half-bridges, and a 200 A reserve range is still available if necessary, for example, as redundancy or in response to (brief) overloads. In such variations with forty first half-bridges and forty second half-bridges (i.e., a total of eighty half-bridges), for the 1 kA test current and the first current sensor device 281 and the second current sensor device 282, the first current sensor device 281 has ten current sensors, wherein the first current sensor is used to acquire the current of a group of four first half-bridges, the second current sensor is used to acquire the current of a group of two second half-bridges consisting of another four first half-bridges, and so on; the second current sensor device 282 has ten corresponding current sensors. Compared to acquiring a correspondingly larger current using a single current sensor, dividing the current acquisition among several current sensors can advantageously reduce weight.

[0050] In some variations where the first / second current sensor device 281 / 282 has multiple current sensors, and particularly where the large current source has multiple operating ranges, the first current sensor device 281 (and correspondingly, the second current sensor device 282) has an additional current sensor. In this case, the current sensor device 281 or 282 is used (particularly for operating ranges with lower maximum test currents such as 100A) to collect the current of the first side 231 or the second side 232 through the additional current sensor, at least within a preset maximum current such as 100A. This advantageous approach improves accuracy. Furthermore, in variations with operating ranges for lower maximum test currents, operational reliability can be improved by limiting the maximum test current to the lower maximum test current.

[0051] In some alternative variations, the high-current source 200 has only one current sensor device, that is, only current sensor device 281 or current sensor device 282. This can further advantageously reduce weight. A particular advantage of the variation that simultaneously provides two current sensor devices 281 and 282 is that it is able to acquire asymmetrical currents.

[0052] In some variations, the first and second controllable switching elements 216, 217, 226, and 227 are discrete components, thereby enabling particularly better distribution of thermal load. In other variations, in each case, discrete components may also be formed by combining multiple controllable switching elements, such as two, four, six, or ten controllable switching elements respectively.

[0053] In some variations, each half-bridge is formed on a respective printed circuit board using SMD (Surface Mount Device) technology, or they are formed together on one or more shared printed circuit boards. This approach advantageously enables lightweight and low-cost structures, and / or allows components to be cooled by the printed circuit board or by airflow passing over the components.

[0054] Finally, the control unit 280 is used, for example, to drive controllable switching elements 216, 217, 226, 227 via control lines, so that they are turned on or off according to changes in the input signal, and in a variation with a feedback loop, further according to the output signal, thereby generating an output signal between the first side 231 and the second side 232 of the bridging branch 230 after filtering that may be performed by the filtering elements. In some variations, the control unit 280 can adjust the test current via current sensor devices 281 and / or current sensor devices 282. As an additional or alternative, in some variations, the control unit 280 can control or adjust the test current via adjusting elements 214 and 224. The high current source 200, especially the control unit 280 and the first set of multiple 210 and the second set of multiple 220 half-bridges, are used to generate at least one alternating current with a maximum frequency of at least 3 kHz, or to generate a direct current, or more generally, to generate a freely adjustable signal form as the test current. In alternative variations, a high-current source can also be used to generate only one AC current, or an AC current with a higher or lower maximum frequency.

[0055] One advantage of direct current (DC) measurement is its ability to test switching (or shut-off) characteristics under fault conditions where DC current occurs, particularly when used for circuit breaker testing, such as so-called "circuit breaker measurements," or for micro-ohm measurements. Another advantage of frequencies at least 3 kHz is its use, for example, in transformer characteristic / ratio testing with current transformers / instrument transformers (i.e., so-called "CT ratio measurement"), especially in so-called "power quality measurements," where transformer characteristics varying with frequency and, if necessary, further with load, can be examined. Variations with freely adjustable signal forms allow for the advantageous superposition of DC currents and / or one or more AC currents of potentially different amplitudes, thereby shortening the measurement time, particularly with at least substantially the same accuracy, or enabling the measurement of nonlinear effects, such as those in "power quality measurements." In variations capable of simultaneously generating DC and AC currents, another advantage is that AC current measurements can be performed directly after the DC current measurement without altering the wiring. For example, in the case of a circuit breaker with a current transformer immediately downstream, a micro-ohmic measurement can be performed first with a DC current, followed by demagnetization with an AC current, allowing the current transformer to be reconnected. For demagnetization, or other processes as part of the measurement process, or processes outside of the measurement process, the high-current source can operate in voltage mode, where the voltage of the output signal, especially rather than the (test) current, is controlled or regulated. For example, for demagnetization, this can be achieved by continuously decreasing the voltage, and thus continuously decreasing the current, through the hysteresis curve until a point of no further magnetization is reached. An advantage of a test current with a maximum current of at least 1 kA is particularly that the electrical device can be tested according to the load, and / or the test current used is already within a range that will not damage the electrical device, and / or corresponds to the rated current of the electrical device, or at least approaches the rated current in a way that improves the accuracy of the test process.

[0056] Some variations of the high-current source 200 include a deviation adjustment device, particularly for improving accuracy. In this case, the high-current source 200 and / or control unit 280 are used to compensate for (residual / residual) DC current deviations or DC voltage deviations, or more generally, the residual deviation between the output signal to be generated based on the input signal and the output signal actually generated by the first and second switchable half-bridges 210, 220. In some variations, such a deviation adjustment device has an analog adjustment device, or is composed of an analog adjustment device.

[0057] In some variations of the energy supply device 240, the energy supply device has multiple double-layer capacitors 241 for buffering positive and / or negative power supply voltages, thereby enabling (temporarily) higher test currents or power, thus avoiding the need for more robust grid connections or (permanently) more powerful and correspondingly heavier energy supply devices. In this case, the multiple double-layer capacitors 241 can be connected in series to achieve higher voltage load capacity. Typically, each such double-layer capacitor has a voltage load capacity of approximately 2.5V. Accordingly, six double-layer capacitors connected in series can buffer a power supply voltage of 15V. One advantage of generating the test current through a combination of multiple first and second half-bridges and double-layer capacitors is that the test current can be generated without a high (positive and / or negative) power supply voltage, thereby enabling sufficiently high dielectric strength with a relatively small number of series-connected double-layer capacitors. This particularly facilitates the balancing of the series-connected double-layer capacitors (e.g., by a balancer) and thus the generation of the current source. Another advantage of this is that, in addition to providing buffered DC voltage or buffered DC current, it can also generate AC current as a test current, and the energy required for this generation can be buffered. As an alternative or additional option, the energy supply device can have other energy storage devices such as rechargeable batteries for buffering or providing energy, eliminating the need for grid connection. A particular advantage of double-layer capacitors is that they can achieve higher current, are lighter, have a longer lifespan, and / or do not present problems in storage or transportation.

[0058] In some variations of the energy supply device 240, the energy supply device has a bidirectional DC / DC converter. For example, in a variation with a test current of 1 kA or less, the energy supply device 240 can be configured via the bidirectional DC / DC converter to supply power to the first and second sets of multiple half-bridges, which are interconnected via bridging branches 230 to form a full bridge, at a power supply voltage of 16V (which may be without a center tap), i.e., the voltage difference between the positive and negative power supply voltages. Advantageously, by incorporating a buffer function, the bidirectional DC / DC converter can be used to provide currents up to 400A. One particular advantage of this bidirectional DC / DC converter is that, for example, when measuring inductors such as transformers, the electrical energy supplied in reverse to a large current source via the test current can be fed back again, particularly via a grid connection, thereby significantly reducing the energy loss of the large current source and consequently reducing the need for cooling.

[0059] Figure 2 The figure shown is a test system 10 for testing electrical devices with a test current according to an embodiment of the present invention.

[0060] In one exemplary embodiment, the test system 10 includes: a portable main device 100 with a housing 104 having a module slot 140 for accommodating and connecting to an expansion module; and a connection device 120 disposed on the housing 104 for connecting to a portable auxiliary device. Furthermore, the test system 10 includes a high-current source 200 as an expansion module. In some variations, the test system 10 also includes at least one portable auxiliary device. In other variations, the test system 10 consists of the portable main device 100 and the high-current source 200. Additionally, in some variations, the test system 10 does not include the connection device 120.

[0061] The high-current source 200 can be designed as described above. Furthermore, the high-current source 200 has a housing 204 for the module slot 140, and an energy supply connection device 248, an input connection device 288, and first and second high-current connectors 236 and 237 disposed on the housing 204. In this case, the first high-current connector 236 is electrically connected to the first side of the bridging branch, and the second high-current connector 237 is electrically connected to the second side of the bridging branch. Additionally, the energy supply device 240 and control unit 280 of the high-current source 200, as well as a first set of multiple first switchable half-bridges and a second set of multiple second switchable half-bridges designed as an integral unit 201, are disposed within the housing 204. In this way, the high-current source 200 can be connected to the portable host device 100 as a test current generation unit.

[0062] In addition, the portable main device 100 includes: a measuring device 160 for measuring the variable to be measured; a control device 180 for controlling the measuring device 160; and a high current source 200 for testing electrical devices.

[0063] Figure 2 The diagram further illustrates the power supply device 30. For testing and test current supply purposes, a first high-current connector 236 is typically connected to a first connection point of the power supply device 30, and a second high-current connector 237 is typically connected to a second connection point of the power supply device 30. Furthermore, for certain measurements / tests, a measuring device 160 may be connected to the first and / or second connection points, or via a test connector or measuring connector (not shown), to other connection points of the power supply device 30, for example, to measure the voltage between the first and second connection points, or for example, to measure the current flowing through at least one connection point under the action of a test current.

[0064] The portable host device 100 is used to control the high-current source 200 via the input connection device 288 and supply energy to the high-current source via the energy supply connection device 248 when the high-current source 200 is housed in the module slot 140. The energy supply device 240 is used to receive electrical energy via the energy supply connection device 248. The control unit 280 is used to receive input signals via the input connection device 288.

[0065] In some variations, the energy supply device 240 has an electrical isolation component 249 and is used to provide positive and negative power supply voltages in a manner that is electrically isolated from the received electrical energy.

[0066] In some variations, the control unit 280 has an electrical isolation component 289 and is used to drive the first and second switchable half-bridges in a manner electrically isolated from the input signals. This approach can be advantageously combined with variations of the control unit 280 for receiving digital input signals.

[0067] like Figure 2 As shown, some variations of the high-current source 200 include a temperature sensor device 268 for acquiring the temperature of the first or second high-current connectors 236, 237 or at least one other part of the high-current source 200. In this case, the control unit 280 is used to activate a fault mode of the high-current source 200 and limit the current of the output signal based on whether the temperature exceeds a preset temperature limit. In some variations, in the fault mode, the current connectors 236, 237 can be isolated from the first and second sides of the bridging branch by a switching device of the high-current source.

[0068] Finally, the high-current source 200 is configured and controlled by the control device 180 to generate an output signal between the first high-current connector 236 and the second high-current connector 237, thereby providing a test current. In this way, a single-phase test current can be advantageously provided between the first high-current connector 236 and the second high-current connector 237.

[0069] Some variations (not shown) of the high-current source 200 are used to generate two-phase or three-phase test currents. For this purpose, in some such variations, a first plurality of first switchable half-bridges are used for, for example, a first phase relative to ground potential or a center tap, and a second plurality of second switchable half-bridges are used for, for example, a second phase relative to ground potential or a center tap. Furthermore, some such variations have a third high-current connector and a third plurality of third switchable half-bridges for the third phase. In this case, the control unit is used to drive the first, second, and third plurality of switchable half-bridges according to input signals, particularly according to three-phase input signals, such that output signals exist respectively between the first and second plurality of switchable half-bridges (i.e., particularly between the first and second high-current connectors), between the second and third plurality of switchable half-bridges (i.e., particularly between the second and third high-current connectors), and between the third and first plurality of switchable half-bridges (i.e., particularly between the third and first high-current connectors), the output signals respectively corresponding to the phases of the corresponding input signals. In this advantageous manner, all three phases of an electrical power unit, especially a three-phase power unit, can be tested separately with a single test current, especially simultaneously, or in a manner that does not require changes to the wiring.

[0070] Figure 3 The diagram shown is a flowchart of the use of a high current source or a test system for testing electrical devices with a test current, according to an embodiment of the present invention.

[0071] In one implementation, the use of 800 includes a start of use 802, an end of use 804, and use steps 820 and 822. The high current source used and the test system used can be designed as described above.

[0072] In step 820, a test current is generated by the high current source or the high current source of the test system described above.

[0073] In step 820, at least one variable to be measured in the test is measured by a high current source or a measuring device of the test system, wherein the at least one variable to be measured is based on at least one measurement signal generated according to the test current.

[0074] In some variations, the test includes at least one measurement selected from the group consisting of: micro-ohm measurement; winding resistance measurement; CT ratio measurement; and circuit breaker measurement. In some variations, the circuit breaker measurement may be a "low-voltage (LV) circuit breaker measurement" for low-voltage circuit breakers.

Claims

1. A high-current source (200) for a test system of an electrical device (30) in an electrical power supply network, characterized in that, include: The first switchable half-bridge (212) is connected in parallel by multiple (210) in the first group, and the test current is redundantly divided by its number; The second group of multiple (220) parallel-connected second switchable half-bridges (222) redundantly divide the test current by their number; as well as A control unit (280) is configured to control, based on an input signal, a first group of multiple (210) first switchable half-bridges (212) and a second group of multiple (220) second switchable half-bridges (222), such that an output signal of the test current exists on a bridging branch (230) between the first switchable half-bridge (212) and the second switchable half-bridge (222), the output signal corresponding to the input signal. The first group of multiple (210) first switchable half-bridges (212) and the second group of multiple (220) second switchable half-bridges (222) are used to generate a current of at least 500A as the test current.

2. The high current source (200) as described in claim 1, characterized in that: Each of the first switchable half-bridges (212) has two controllable switching elements (216, 217) connected in series with the connection point (218); Each of the second switchable half-bridges (222) has two controllable switching elements (226, 227) connected in series with the connection point (228); Each of the connection points (218) of the first switchable half-bridge (212) is connected in parallel and electrically connected to the first side (231) of the bridging branch (230); Each of the connection points (228) of the second switchable half-bridge (222) is connected in parallel and electrically connected to the second side (232) of the bridging branch (230); The control unit (280) is used to control the controllable switching element.

3. The high current source (200) as described in claim 2, characterized in that: The connection point (218) of each of the first switchable half-bridges (212) is electrically connected to the first side (231) of the bridging branch via a filter element (213); and The connection point (228) of each of the second switchable half-bridges (222) is electrically connected to the second side (232) of the bridging branch via a filter element (223).

4. The high current source (200) as described in claim 2, characterized in that, Also includes: A first high-current connector (236) for connecting the first connection point of the electrical device (30); as well as The second high-current connector (237) is used to connect the second connection point of the electrical device (30). The first high-current connector (236) is electrically connected to the first side (231) of the bridging branch, and the second high-current connector (237) is electrically connected to the second side (232) of the bridging branch.

5. The high current source (200) as described in claim 4, characterized in that, It also includes a temperature sensor device (268) for collecting the temperature at the first high-current connector (236) or the second high-current connector (237), wherein the control unit (280) is used to activate the fault mode of the high-current source (200) according to whether the temperature is higher than a preset temperature limit, and to limit the current of the output signal.

6. The high current source (200) as described in claim 2, characterized in that, It also includes a positive power rail (242) for distributing a positive power supply voltage and a negative power rail (246) for distributing a negative power supply voltage, wherein one of the two controllable switching elements (216; 226) of each of the first switchable half-bridges (212) and each of the second switchable half-bridges (222) is electrically connected to the positive power rail (242), and the other of the two controllable switching elements (217; 227) of each of the first switchable half-bridges (212) and each of the second switchable half-bridges (222) is electrically connected to the negative power rail (246).

7. The high current source (200) as described in claim 1, characterized in that, It also includes an energy supply device (240) having a plurality of double-layer capacitors (241) for providing positive and negative power supply voltages to the first switchable half-bridge (212) and the second switchable half-bridge (222), and for buffering the positive and / or negative power supply voltages through the double-layer capacitors.

8. The high current source (200) as described in claim 7, characterized in that, The energy supply device (240) is used to receive electrical energy via the energy supply connection device (248) of the high current source, and to provide the positive power supply voltage and the negative power supply voltage in a manner that is electrically isolated (249) from the received electrical energy.

9. The high current source (200) as described in claim 1, characterized in that, The control unit (280) is used to receive the input signal via the input connection device (288) of the high current source, and to control the first switchable half bridge (212) and the second switchable half bridge (222) in a manner electrically isolated (289) from the input signal.

10. The high current source (200) as described in claim 1, characterized in that, It also includes a current sensor device (281, 282) having multiple current sensors, wherein the high current source (200) is used to adjust the DC voltage deviation and / or DC current deviation by means of a deviation adjustment device of the high current source.

11. The high current source (200) as described in claim 1, characterized in that, The number of the first switchable half-bridge (212) or the number of the second switchable half-bridge (222) is at least twenty; and / or the number of the first switchable half-bridge (212) is equal to the number of the second switchable half-bridge (222).

12. The high current source (200) as described in claim 1, characterized in that, The first group of multiple (210) first switchable half-bridges (212) and the second group of multiple (220) switchable half-bridges (222) are used to generate at least one AC current or DC current with a frequency of at least 3 kHz as the test current.

13. The high current source (200) as described in claim 1, characterized in that, The first group of multiple (210) first switchable half bridges (212) and the second group of multiple (220) second switchable half bridges (222) are designed as an integral unit (201) and housed in a common housing (204).

14. A test system (10) for testing an electrical energy device (30) using a test current, characterized in that, include: A portable main device (100) includes: a housing (104) having a module slot (140) for receiving and connecting an expansion module; and a connection device (120) disposed on the housing (104) for connecting a portable auxiliary device; and As the extended module, the high current source (200) as described in claim 1, The high-current source (200) further includes a housing (204) for the module slot (140), and an energy supply connection device (248), an input connection device (288), and first and second high-current connectors (236; 237) disposed on the housing (204). The portable host device (100) also includes: A measuring device (160) for measuring the variable to be measured; and Control device (180) for controlling the measuring device (160) and the high current source (200) for testing the electrical power device (30), The portable main device (100) is used to control the high current source (200) via the input connection device (288) and supply energy to the high current source via the energy supply connection device (248) when the high current source (200) is housed in the module slot (140). The high current source (200) is configured and controlled by the control device (180) to generate an output signal between the first high current connector (236) and the second high current connector (237) to provide the test current.

15. The use of the high current source as claimed in claim 1 or the test system as claimed in claim 14 for testing an electrical energy device with a test current (800).

16. The use (800) as described in claim 15, characterized in that, The test includes at least one measurement performed by the measuring device (160), the at least one measurement being selected from: - Micro-ohm measurement; - Winding resistance measurement; - Transformer ratio measurement; and - Circuit breaker measurement.

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