Multi-channel test system with galvanic coupling of intermediate circuits and method for galvanic coupling of intermediate circuits

Description

[0001] The present invention relates to multi-channel test systems and a method for supplying test load devices with electrical power from a supply network, which comprise a coupling of DC-carrying intermediate circuits from galvanically isolated test channels.

[0002] Such multi-channel test systems are used, for example, in the development and stationary testing or inspection of electric drive systems or electrical on-board systems in vehicles, in which several interacting electrical assemblies, in particular consumers and storage devices such as traction motors and traction batteries, as well as auxiliary units for air conditioning or the like, are supplied with electrical power from a supply network during test runs on a test bench. Test systems with multiple channels offer greater flexibility, as they enable individual power supply with configurable voltage as required for different test objects on the test bench via multiple channel outputs. In the respective channels, an individually adjustable or controllable voltage conversion takes place between an AC voltage from the mains and a DC voltage or DC current for a connected consumer.

[0003] Corresponding multi-channel test systems are known, such as those from US 2020 / 176994 A1, whose circuitry provides galvanic isolation between the channels, more precisely starting at an individual power level of each channel. This means that power transformation from the mains to the channel or from the channel back to the mains takes place in each channel via a separate mains rectifier, with the mains rectifiers of all channels coupled to the mains via a transformer.

[0004] Galvanic isolation has the advantage that the supply stability of power parameters of a channel output is not affected by fluctuations in power flows in parallel test channels. This applies in particular to measurements of insulation resistance to ground, which are sensitive to neighboring power fluctuations. An output stage that can be individually configured for the load is connected downstream of the channel output. This output stage is usually fed by a constant direct current generated from a DC link after power transformation. On the other hand, the advantage of supply stability comes with the disadvantage of a limited power capacity of each channel, which is determined by a portion of the total capacity of the shared transformer that is made available to each of the parallel channels.

[0005] Furthermore, such multi-channel test systems are known in which a channel can have multiple channel outputs. In this case, an intermediate circuit is provided in a central section of the channel. This circuit carries a constant direct current at a constant direct voltage of, for example, 820V or 1250V, which is fed from the power transformation of the mains rectifier. The intermediate circuit connects the mains rectifier to the channel outputs of the channel, with the individual output stages of the channel outputs being jointly supplied with direct current from the mains rectifier from the intermediate circuit, i.e., they are galvanically coupled.

[0006] Configuring a galvanically coupled supply for multiple channel outputs via a common channel intermediate circuit has the advantage of enabling power flow between the loads connected to the channel outputs of the same channel. In the case where a load is a storage device, i.e., it can provide power output in addition to power input, it is possible to temporarily supply a high-power load with a peak power that exceeds the channel's power transformation capacity from the grid or the grid connection rating of the transformer.On the other hand, this advantageous capacity increase for a connected consumer with pronounced power peaks can only be used under the aforementioned constellation of a storage device among the connected consumers as well as other variable conditions such as a storage state and capacity as well as time-limited dependencies.

[0007] At least theoretically, with the objective of increasing the maximum mains connected power that can be made available to a high-power consumer at a channel output, another test system configuration would be conceivable, although to the applicant's knowledge, no practical implementation has yet been reported. Theoretically, two single-channel test devices could be connected via their intermediate circuits, from which an output stage or parallel output stages for the high-power consumer would be fed. However, coupling two mains-fed intermediate circuits would cause damagingly high compensating currents even with small voltage differences in the range of measurement and control errors (e.g., 0.25% at a voltage of 1200V).The problem could only be addressed by cost-intensive technical effort such as a high-current contactor switch in combination with improved control and more precise measurement technology to synchronize the power transformations that feed the intermediate circuits in parallel, as well as considerable compensation times during each coupling process to limit the compensation current.

[0008] It is an object of the invention to overcome the aforementioned disadvantages of test systems in the prior art. It is a further object of the invention to create a test system of the type mentioned above that, on the one hand, offers high flexibility in the parallel provision of an individually configurable power supply to different consumers on a test bench, and, on the other hand, enables a high capacity of the grid connection power as well as the power transformation for individual high-power consumers. Furthermore, it is an object of the present invention to minimize the time required to operate the test system when switching between the provided configurations based on the technical features.

[0009] The above objects are achieved by a multi-channel test system for supplying test consumer devices with the features of claim 1 and a method for supplying test consumer devices with the steps of claim 9. Further features and details of the invention emerge from the subclaims, the description, and the drawings. Features and details described in connection with the multi-channel test system according to the invention naturally also apply in connection with the method according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0010] According to the invention, a multi-channel test system is provided for supplying test load devices with electrical power from a supply network. The multi-channel test system comprises at least a first test channel and a second test channel, each comprising at least one channel output for providing power with a predetermined output voltage for test load devices. Each of the test channels is galvanically isolated and has a controllable power converter circuit and an intermediate circuit, as well as one or more channel outputs. The controllable power converter circuit serves for the controlled conversion of electrical power between the supply network and the DC-carrying intermediate circuit of the test channel. Each channel output comprises an output stage connected to the intermediate circuit for converting a DC voltage between the intermediate circuit and the predetermined output voltage of the channel output.The multi-channel test system also includes a switching device connected to at least the intermediate circuits of the first test channel and the second test channel, and arranged for switchable galvanic coupling of the intermediate circuits to a common intermediate circuit, as well as for switchable galvanic isolation of the intermediate circuits. Furthermore, the controllable power converter circuits of at least the first test channel and the second test channel include an active power stage configured to provide both phase-controlled, variably adjustable rectification in an active operating mode and uncontrolled, invariable rectification in a passive operating mode.

[0011] Analogously, the invention provides a method for supplying test load devices with electrical power from a supply network by means of a multi-channel test system with at least two galvanically isolated test channels. One step of the method consists in converting an alternating voltage between the supply network and each test channel by means of a transformer in each test channel. A further step of the method consists in rectifying the alternating voltage between the transformer and a DC-carrying intermediate circuit by means of an active power stage in each test channel, wherein the rectification can be converted between a phase-controlled, variably adjustable rectification by means of an active operating mode and an uncontrolled, invariable rectification by means of a passive operating mode of the active power stage.A further step of the method consists in converting a DC voltage between the DC-carrying intermediate circuit and a predetermined output voltage for test load devices by means of at least one output stage in each test channel. A further step of the method consists in galvanically coupling intermediate circuits of at least two test channels to a common intermediate circuit or galvanically isolating the intermediate circuits by means of a switching device, provided that the rectification in the active power stages of the at least two test channels has previously been converted to uncontrolled, invariable rectification by means of the passive operating mode.

[0012] The present invention thus provides, for the first time, a circuit architecture for a multi-channel test system with switchable coupling and isolation of intermediate circuits from galvanically isolated test channels. In particular, the present invention provides such a circuit architecture with galvanically isolated transformers. For this purpose, the present invention proposes, for the first time, technical prerequisites and an operating mode for the favorable handling of switchable coupling and isolation of intermediate circuits.

[0013] One advantage of the invention lies in the flexible configuration enabled by the multi-channel test system. If only one output stage for a channel output connected to a load is supplied from each test channel, the load is galvanically isolated and is not affected by power fluctuations in other test channels. Thus, the test channels of the multi-channel test system according to the invention can be operated in the same way and with the specific advantages of several single-channel test devices. In test applications where galvanic isolation is not relevant, power balancing between output stages of channel outputs connected to different types of loads can be achieved directly via the intermediate circuit, without power transformation to the supply network.

[0014] A further advantage of the invention lies in the flexible increase in the available power capacity for a single consumer by a switchable combination of all components from two galvanically isolated test channels.

[0015] When the intermediate circuits of such two test channels are galvanically coupled, a common intermediate circuit is fed with the combined capacities of the available mains connection power of two or more transformers and the available power transformation of two or more power converter circuits. This allows one or more parallel-connected output stages connected to a high-power load such as an electric traction drive to be fed with a high reserve of power capacity, while even high power fluctuations can be covered via the mains connection of the multi-channel test system alone. In other words, a channel output is no longer limited by the assigned power capacity of the channel in a multi-channel test system or the power of a transformer in a single-channel test device.

[0016] A further advantage is practical handling and rapid conversion between single-channel and multi-channel circuit configurations of the test system for different test operations. One aspect of the present invention is based on the finding that very good approximation of intermediate circuit voltages and thus a low compensation potential can be achieved in passive operation of the mains rectifiers for power transformation in the power converter circuits or their active power stages. This is because after the mains rectifiers are stopped, the initially regulated intermediate circuit voltage assumes a passive rectification value, which, under passive, unregulated rectification in the sense of a diode, establishes an equilibrium between the circuit components.This passive mode is achieved quickly and specifically after the active mode of a regulator of a regulated mains rectifier by actively reducing the otherwise constant DC link voltage to a passive value and then stopping the regulation. Consequently, in practice, no waiting time is required to reach the passive mode through self-discharge of the DC link.

[0017] Due to the shared mains voltage, the deviation of the intermediate circuit voltages at this operating point can only be influenced by the winding ratios of the transformer coils. With identical component types and properties between the channels, only a minimal deviation between the voltages occurs, which is below the deviation that would be achievable between regulated voltages with greater control and measurement effort during active operation.

[0018] Accordingly, the compensating current can be kept low, i.e., there is no need for a pre-charging circuit to protect the contactor from high currents during the switching operation. Furthermore, there is a considerable saving of time, since the active reduction of the voltage to passive mode means no waiting time is required for the intermediate circuit to discharge itself. In practice, the entire process can thus be shortened from a few minutes to a few seconds. In summary, the provision of passive, unregulated rectification, i.e., the provision of a corresponding operating mode in a power converter circuit or an active power stage of the multi-channel test system according to the invention contained therein, as well as the establishment of a corresponding condition and temporary use of the operating mode in the method according to the invention, results in a considerable time advantage when converting the test system between single-channel and multi-channel circuit configurations.In other words, the provision of a passive, unregulated rectification enables the aforementioned conversion by means of a user-friendly switching process with little control and measurement effort.

[0019] In one embodiment, the controllable power converter circuits of the galvanically isolated test channels comprise an upstream transformer and a downstream active power stage. The transformer, which is connected to the supply network, serves to convert an AC voltage between the supply network and the test channel. The active power stage, which is connected to the transformer, serves to rectify the AC voltage between the transformer and the DC-carrying intermediate circuit, and provides the active operating mode for phase-controlled, variably adjustable rectification and the passive operating mode for uncontrolled, invariable rectification.

[0020] In an alternative embodiment, the controllable power converter circuits of the galvanically isolated test channels comprise an upstream active power stage and a downstream intermediate circuit voltage regulator. The active power stage, which is connected to the supply network, serves to convert an alternating voltage between the supply network and the test channel; and provides the active operating mode for phase-controlled, variably adjustable rectification as well as the passive operating mode for uncontrolled, invariable rectification. The intermediate circuit voltage regulator, which is connected to the active power stage (12, 22, 32), serves to controllably convert a direct voltage between the active power stage and the DC-carrying intermediate circuit.

[0021] InIn an advantageous embodiment of the present invention, the multi-channel test system further comprises a control unit which is configured to switch a galvanic coupling or separation of intermediate circuits by means of the switching device or to provide a switching actuation when the rectification in the active power stages of the respective test channels has been transferred to the passive operating mode.

[0022] In a further advantageous embodiment of the present invention, the multi-channel test system further comprises voltage sensors for detecting a voltage of intermediate circuits; wherein the control unit is further configured to switch a galvanic coupling or separation of intermediate circuits by means of the switching device or to provide a switching actuation when the voltages in the intermediate circuits reach a respective or a common predetermined threshold value Su.

[0023] According to an advantageous aspect of the present invention, the respective or common threshold value Su is predetermined in relation to reaching a passive voltage level of the respective intermediate circuit, which is self-adjusted in an equilibrium of the voltage conversions of the respective test channel in the passive operating mode of the rectification.

[0024] In an advantageous embodiment of the present invention, at least the first test channel and second test channel each have a transformer and an active power stage with the same conversion properties, whereby a substantially identical passive voltage level is established in the respective intermediate circuits, and wherein a common threshold value Su is predetermined in relation to reaching the passive voltage level.

[0025] In an advantageous embodiment of the present invention, the multi-channel test system further comprises a timer for specifying a predetermined time period; wherein the control unit is further configured to transfer the rectification from the passive operating mode back to the active operating mode or to enable a transfer operation when a predetermined time period has elapsed after completion of a switching operation for the galvanic coupling or separation of intermediate circuits.

[0026] According to one aspect of the present invention, the control unit is further configured to switch a galvanic coupling or separation of the intermediate circuits by means of the switching device or to provide a switching actuation when a supply of all test consumer devices from an associated intermediate circuit has been interrupted.

[0027] In an advantageous embodiment of the present invention, each output stage comprises a disconnect switch arranged for switchably disconnecting the channel output from the associated intermediate circuit or for switchably disconnecting the channel output from an associated test load device; and the control unit is further configured to switch disconnection of at least those channel outputs connected to a test load device by means of the disconnect switches or to provide switching actuation.

[0028] Further advantages, features, and details of the invention will become apparent from the following description, which describes embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. Fig. 1 shows a block diagram illustrating a circuit of components of the multi-channel test system according to a first embodiment of the invention. Fig. 2 shows a block diagram illustrating a circuit of components of the multi-channel test system according to a second embodiment of the invention. Detailed description of embodiments of the invention

[0029] In Fig. 1A first embodiment of a multi-channel test system 100 according to the invention with three parallel test channels 10, 20, 30 is schematically sketched in a block diagram. The multi-channel test system 100 serves to supply test load devices 61, 62 with electrical power from a supply network (not shown). For this purpose, the multi-channel test system 100 has network connections, which are schematically shown on a top side. Channel outputs are shown on a bottom side, which are connected to the various test load devices 61, 62 with different assignments, either individually or in parallel.

[0030] The test load devices 61, 62 can be components of an electric drive system on a test bench that is subjected to various test runs. The test load devices 61, 62 can be of different types, such as an electric motor or a battery. In the illustrated embodiment, the test load device 61 is a comparatively powerful traction motor that is supplied with power from the two test channels 10 and 20, and the test load device 62 is a smaller electric motor, representing, for example, a compressor of an air conditioning system. The test channels 10 and 20 not only supply a different power to the respective channel output, but also a different, higher output voltage or required operating voltage to the test load device 61 than the test channel 30 at the test load device 62.The performance parameters such as the output voltage can be individually configured using test channels 10, 20, and 30.

[0031] The circuit of test channel 10 comprises, in a line-input-side section, a controllable power converter circuit (16), which in this first embodiment consists of an upstream transformer 11 and a downstream active power stage. Transformer 11 is an AC / AC converter connected to the supply network via the mains connection. Transformer 11 converts an AC voltage from the mains voltage into a system voltage and supplies active power stage 12. Active power stage 12 is a controllable AC / DC converter that converts the AC voltage of the system voltage into a DC voltage of a direct current and feeds an intermediate circuit 13 of test channel 10. Active power stage 12 has a regulated mains rectifier (MR), which, on the one hand, assumes the function of an AC / DC converter.It also features phase-controlled rectification with variable power transformation, which generates requested or demand-based power at a predeterminable regulated voltage for the intermediate circuit. Furthermore, the regulated mains rectifier has two operating modes and a multitude of intermediate transitional operating states for rectifying AC voltage to DC voltage. In an active operating state of the active power stage 12, the regulated mains rectifier performs the previously described phase-controlled rectification with variable power transformation. In a passive operating state of the active power stage 12, the regulated mains rectifier performs uncontrolled rectification, which corresponds to the function and operating mode of a passive circuit with a diode. An output stage 14 is supplied from the intermediate circuit 13.The output stage 14 is in particular a step-down converter (STDC) which converts the voltage fed into the intermediate circuit 13 by the active power stage 12 into a specific or individually predetermined output voltage of the relevant channel output for the test load devices 61 connected thereto.

[0032] In the embodiment of the invention, the test channel 20 corresponds to the test channel 10 and has not only the same schematic circuit design, but also the same components and conversion properties with regard to an identical component typing of the transformer 21, the active power stage 22, or the regulated mains rectifier contained therein, and optionally, with regard to the channel assignment of the illustrated embodiment, also the output stage 24. In the embodiment of the invention, the test channel 30 also corresponds to the test channel 10 with regard to an identical component typing of the transformer 31, the active power stage 32, or the regulated mains rectifier contained therein.In the illustrated embodiment of the channel assignment, for the purpose of illustrating configuration options, test channel 30 differs from test channels 10 and 20 in that it optionally has two channel outputs, each with an associated output stage 34, one of which is unassigned and one of which is connected to the test load device 62. Both output stages 34, which can optionally be configured with different output voltages, are supplied from the same intermediate circuit 33 of test channel 30. The three test channels 10, 20, 30 are galvanically isolated, i.e., in particular, all DC-carrying components of the circuit of each test channel 10, 20, 30, and in the present embodiment also the transformers 11, 21, 31, are connected in parallel to one another without cross-influences.

[0033] The multi-channel test system 100 further comprises a switching device 40, which is connected to the intermediate circuit 13 of the first test channel 10, the intermediate circuit 23 of the first test channel 20, and the intermediate circuit 33 of the first test channel 30. By setting the switching device 40 in different positions, the intermediate circuit 13 and the intermediate circuit 23, or the intermediate circuit 23 and the intermediate circuit 33, or the intermediate circuit 13 and the intermediate circuit 33, or even all three intermediate circuits 13, 23, 33 can be combined into a common intermediate circuit, i.e., galvanically coupled. The switching device 40 is implemented as a contactor or contactor switch.

[0034] A common intermediate circuit coupled in this way in a combination of two or three test channels 10, 20, 30 results in the channel outputs or their output stages 14, 24, 34 also being galvanically coupled to one another, i.e., a power distribution with a balancing power flow among the test channels 10, 20, 30 takes place via the common intermediate circuit. On the other hand, a common intermediate circuit coupled in this way enables a doubling or tripling of the power capacity available from the supply network and available on the output side for one of the test consumer devices 61, 62, without, in principle, having to construct a new circuit structure of the test system 100 or having to maintain a larger-dimensioned transformer for converting the test system 100.

[0035] When channeling the Fig. 1In the illustrated embodiment, the test load device 61 represents a high-performance load such as a traction motor, for which sufficient power reserves are to be provided during test operation under full load. Accordingly, in the illustrated embodiment, the intermediate circuits 13 and 23 are connected to a common intermediate circuit via the switching device 40. This galvanically couples the output stages 14 and 24, or the channel outputs of the test channels 10 and 20, which jointly supply power to the test load device 61. In the illustrated embodiment, however, the intermediate circuit 33 of the test channel 30 has not been coupled by the switching device 40, so that the two output stages 34 remain galvanically coupled to one another, but are galvanically isolated from the output stages 14, 24 and remain unaffected by the high power flows through the test channels 10 and 20.

[0036] Deviating from Fig. 1 In a functionally equivalent circuit, only one channel output from the test channel 10 or from the test channel 20 may also be connected to the test consumer device 61.

[0037] Furthermore, the multi-channel test system 100 comprises a control unit 50, which serves to control, i.e., within the meaning of the present disclosure, to control and / or regulate the switching operations of the switching device 40 as well as the previously described operating modes of the rectification of the regulated mains rectifiers in the controllable power converter circuits (16, 26, 36), i.e., more precisely, in the active power stages 12, 22, 32 of the controllable power converter circuits (16, 26, 36). For this purpose, the control unit 50 can preferably be controlled via an operating interface to actuate changes to the circuit configuration, in particular to carry out couplings and disconnections of the intermediate circuits 13, 23, 33.From a process engineering perspective, the present invention further provides that the control unit 50 carries out, releases, or permits switching operations of the switching device 40 or external actuation by a user only under certain conditions, in particular under the previously described passive operating mode of rectification in the test channels 10, 20, 30 involved.

[0038] In Fig. 2 A second embodiment of the multi-channel test system 100 according to the invention with three parallel test channels 10, 20, 30 is schematically sketched in a block diagram. The multi-channel test system 100 of the second embodiment in Fig. 2 differs from the first embodiment Fig. 1only in the structure of the controllable power converter circuits (16, 26, 36). Functionally, in the second embodiment, an AC / DC conversion is implemented first, followed by a DC / DC conversion, instead of an AC / AC conversion and a subsequent AC / DC conversion, as in the first embodiment.

[0039] For this purpose, in each test channel (10, 20, 30), the active power stage (12, 22, 32), which is a controllable AC / DC converter, is directly connected to the supply network (i.e., without an upstream transformer). The active power stage converts an AC voltage from the supply network into a rectified system voltage and supplies an intermediate circuit voltage regulator (15, 25, 35). The intermediate circuit voltage regulator (15, 25, 35) is a galvanically isolating DC / DC converter that converts the DC voltage of the rectified system voltage into a DC voltage of the DC-carrying intermediate circuit (13, 23, 33) of the respective test channel (10, 20, 30).Apart from the different circuit position of the active power stage (12, 22, 32) in the second embodiment, this, in accordance with the first embodiment, again has a regulated mains rectifier (MR), which assumes the function of an AC / DC converter, and a phase-controlled rectification with variable power transformation, which generates a requested or demand-based power at a predeterminable regulated voltage for the intermediate circuit. Likewise, the regulated mains rectifier in the second embodiment, as in the first embodiment, has two operating modes and a plurality of intermediate transitional operating states with respect to an operating mode of rectification from AC voltage to DC voltage. In an active operating state of the active power stage 12, the regulated mains rectifier performs the previously described phase-controlled rectification with variable power transformation.In a passive operating state of the active power stage 12, the regulated mains rectifier performs an uncontrolled rectification which corresponds to the function and operation of a passive circuit with a diode.

[0040] In the first and second embodiments of the multi-channel test system 100 of the Figures 1 and 2 A check of the operational requirements for a switching operation can be supported by optional additional metrological measures and conditions, as described below. However, the multi-channel test system 100 according to the invention can also be operated manually, in particular switched, without the following functions and without the control unit 50, simply by providing suitable actuating elements and adhering to a logic of operating steps.

[0041] To ensure low and short compensating currents, each switching operation of the switching device 40, especially during coupling, takes place with the output stages 14, 24, 34 switched off, in order to keep the voltages in the intermediate circuits 13, 23, 33 stable. This process can be performed manually, for example, using provided disconnect switches.

[0042] The switching operations of the switching device 40 for changing the circuit configuration can be performed without disconnecting the multi-channel test system 100 from the supply network. Starting from an active rectification operating mode, the intermediate circuit voltages are first actively reduced to almost a passive rectification value by the regulated mains rectifiers of the active power stages 12, 22, 32 of the test channels 10, 20, 30 involved in the coupling. The active reduction can occur relatively quickly, e.g., from 1250 V to 1045 V in a few 100 ms, since this depends on a selected voltage ramp in an intermediate circuit voltage regulation function of the active power stages 12, 22, 32 according to the first embodiment, or by means of an intermediate circuit voltage regulator (15, 25, 35) according to the second embodiment.Once the regulated mains rectifiers have been transferred to the passive operating state, a short wait is made until the regulated intermediate circuit voltage has been reduced by further passive discharge to the passive rectification value or a voltage equilibrium.

[0043] While the reduction to the passive operating mode of the regulated mains rectifiers in the power stages 12, 22, 32 when closing the switching device 40 ensures that the voltages of the intermediate circuits are exact and steady before closing, the reduction to passive operating mode when separating the switching device 40 ensures that the active control of the mains rectifiers in the power stages 12, 22, 32 does not allow any cross currents to flow via the switching device 40, ie the contactor, at the moment of opening.

[0044] For this purpose, the voltage can be detected at the intermediate circuits 13, 23, 33 manually or by the control unit 50 using voltage sensors, and any undershoot of all voltages below a threshold value Su, which is approximated or predefined in relation to the rectified value, can be detected. Alternatively, a predefined period of time can be waited for manually or by the control unit 50, after which the desired voltage approximation is assumed.

[0045] After a switching operation of the switching device 40 has been completed, the regulated mains rectifiers of the active power stages 12, 22, 32 of the test channels 10, 20, 30 involved in the coupling are transferred manually or by the control unit 50 from the passive operating state back to the active operating state. A voltage vector of the supply network is tracked throughout the passive operating state. The control unit 50 raises a setpoint of individual or coupled intermediate circuits 13, 23, 33, and software of the controllers of the mains rectifiers in the power stages 12, 22, 32 detects, through a comparison between the setpoint and the passive value, that active switching of power is required. As a result, a voltage of the common intermediate circuit is increased from the passive rectification value to a predetermined regulated voltage, which is predefined according to a new configuration of the multi-channel test system 100.

[0046] As an alternative to the switching operations described, it is also possible to separate the intermediate circuits if both rectifiers are switched off anyway.

[0047] The galvanic coupling of the intermediate circuits 13, 23, 33 is accompanied by a logical coupling of the mains rectifier control, which enables operation without dynamic restrictions.

[0048] Preferably, the switching process of coupling and disconnecting is specified by the control unit 50, ie from a central location in the system, which also handles the user interaction and the circuit or contactor control.

[0049] The above explanations of the embodiments describe the present invention exclusively by way of examples. Of course, individual features of the embodiments can be freely combined with one another, provided they are technically feasible, without departing from the scope of the present invention. List of reference symbols

[0050] 10Test channel 11Transformer (AC / AC converter) 12Active power stage (AC / DC converter) 13Intermediate circuit 14Output stage 15Intermediate circuit voltage regulator (DC / DC converter) 16Controllable power converter circuit (AC / AC+AC / DC converter or AC / DC+DC / DC converter) 20Test channel 21Transformer 22Active power stage 23Intermediate circuit 24Output stage 30Test channel 31Transformer 32Active power stage 33Intermediate circuit 34Output stage 40Switching device 50Control unit 61Test load device 62Test load device 100Multi-channel test system SuThreshold for intermediate circuit voltages SI Threshold for compensating current

Claims

1. Multi-channel test system (100) for supplying test consumer devices (61, 62) with electrical power from a supply network, comprising at least a first test channel (10) and a second test channel (20), each comprising at least one channel output for providing power at a predetermined output voltage to test consumer devices (61, 62), wherein the test channels (10, 20, 30) are galvanically isolated; and each test channel (10, 20, 30) comprises a power conversion circuit (16, 26, 36) for controlled conversion of electrical power between the supply network and a DC link (13, 23, 33) of the test channel (10, 20, 30);each channel output comprises an output stage (14, 24, 34) connected to the DC link (13, 23, 33) for converting a DC voltage between the DC link (13, 23, 33) and the predetermined output voltage of the channel output; and the test channels (10, 20, 30) each comprise at least one channel output for providing a power having a predetermined output voltage to test consumer devices (61, 62), wherein the test channels (10, 20, 30) are galvanically isolated; and at least one switching device (40), which is connected at least to the intermediate circuits (13, 23) of the first test channel (10) and second test channel (20), and is arranged for the switchable galvanic coupling of the intermediate circuits (13, 23) to form a common intermediate circuit and for the switchable galvanic isolation of the intermediate circuits (13, 23); wherein at least the power converter circuits (16, 26) of the first test channel (10) and second test channel (20) have an active power stage (12, 22) which is set up to provide both a phase-controlled, variably adjustable rectification of an AC voltage in an active operating mode and an uncontrolled, invariable rectification in a passive operating mode.

2. Multi-channel test system (100) according to claim 1, wherein the controllable power converter circuits (16, 26, 36) of the galvanically isolated test channels (10, 20, 30) comprise: an upstream transformer (11, 21, 31), which is connected to the supply network, for converting an AC voltage between the supply network and the test channel (10, 20, 30); and downstream, the active power stage (12, 22, 32), which is connected to the transformer (11, 21, 31), for rectifying the AC voltage between the transformer (11, 21, 31) and the DC link (13, 23, 33), and which provides the active operating mode for phase-controlled, variably adjustable rectification and the passive operating mode for uncontrolled, invariable rectification.

3. Multi-channel test system (100) according to claim 1, wherein the controllable power conversion circuits (16, 26, 36) of the galvanically isolated test channels (10, 20, 30) comprise: an active power stage (12, 22, 32) connected to the supply network for converting an AC voltage between the supply network and the test channel (10, 20, 30); and upstream, the active power stage (12, 22, 32), which is connected to the supply network, for converting an AC voltage between the supply network and the test channel (10, 20, 30); and which provides the active operating mode for phase-controlled, variably adjustable rectification and the passive operating mode for uncontrolled, invariable rectification; and a downstream DC link voltage regulator (15, 25, 35) connected to the active power stage (12, 22, 32) for controlled conversion of a DC voltage between the active power stage (12, 22, 32) and the DC link (13, 23, 33).

4. Multi-channel test system (100) according to one of claims 1 to 3, further comprising a control unit (50), wherein the control unit (50) is arranged to switch a galvanic coupling or isolation of intermediate circuits (13, 23, 33) by means of the switching device (40) or to provide a circuit actuation when the rectification in the active power stages (12, 22) of the respective test channels (10, 20, 30) has been transferred to the passive operating mode.

5. Multi-channel test system (100) according to claim 4, further comprising voltage sensors for detecting a voltage of intermediate circuits (13, 23, 33); wherein the control unit (50) is further arranged to switch a galvanic coupling or isolation of intermediate circuits (13, 23, 33) by means of the switching device (40) or to provide a circuit actuation when the voltages in the intermediate circuits (13, 23, 33) reach a respective or a common predetermined threshold value Su.

6. Multi-channel test system (100) according to claim 5, wherein the respective or common threshold Su is predetermined with respect to reaching a passive voltage level of the respective DC link (13, 23, 33) which is set in a balance of the voltage conversions of the respective test channel (10, 20, 30) in the passive operation mode of the rectification itself.

7. Multi-channel test system (100) according to claim 5 or 6, wherein at least the first test channel (10) and second test channel (20) each have a transformer (11, 21) and an active power stage (12, 22) with the same conversion characteristics, as a result of which a substantially identical passive voltage level is set in the respective intermediate circuits (13, 23), and wherein a common threshold value Su is predetermined in relation to reaching the passive voltage level.

8. Multi-channel test system (100) according to claim 1 to 7, further comprising a timer for setting a predetermined time duration; wherein the control unit (50) is further arranged to transfer the rectification from the passive operating mode back to the active operating mode or to enable a transfer operation when a predetermined time period has elapsed after completion of a switching operation for galvanic coupling or isolation of intermediate circuits (13, 23, 33)..

9. Multi-channel test system (100) according to claim 1 to 8, wherein the control unit (50) is further arranged to switch a galvanic coupling or isolation of the intermediate circuits (13, 23, 33) by means of the switching device (40) or to provide a circuit actuation when a supply to all test consumer devices (61, 62) from an associated intermediate circuit (13, 23, 33) has been interrupted.

10. Multi-channel test system (100) according to claim 1 to 9, wherein each output stage (14, 24, 34) has an isolating switch which is arranged for the switchable isolation of the channel output from the associated intermediate circuit (13, 23, 33) or for the switchable isolation of the channel output from an associated test consumer device (61, 62).

11. Method for supplying test consumer devices (61, 62) with electrical power from a supply network by means of a multi-channel test system (100) with at least two galvanically isolated test channels (10, 20, 30), comprising the steps of converting electrical power between the supply network and a DC link (13, 23, 33) of each test channel (10, 20, 30) by means of a power converter circuit (16, 26, 36); including the intermediate steps of: rectifying the AC voltage between a transformer (11, 21, 31) and a DC link (13, 23, 33) or rectifying the AC voltage between the supply network and a DC link voltage regulator (15, 25, 35), by means of an active power stage (12, 22, 32) in each test channel (10, 20, 30); wherein the rectification can be converted between a phase-controlled, variably adjustable rectification by means of an active operating mode and an uncontrolled invariable rectification by means of a passive operating mode of the active power stage (12, 22, 32); converting a DC voltage between the DC link (13, 23, 33) and a predetermined output voltage for test consumer devices (61, 62) by means of at least one output stage (14, 24, 34) in each test channel (10, 20, 30); and galvanically coupling intermediate circuits (13, 23, 33) of at least two test channels (10, 20, 30) to a common intermediate circuit or galvanically isolating the intermediate circuits (13, 23, 33) by means of a switching device (40), if the rectification in the active power stages (12, 22, 33) of the at least two test channels (10, 20, 30) has been converted to uncontrolled, invariable rectification by means of the passive operating mode.

12. Method according to claim 11, further comprising the intermediate step of: detecting a voltage of intermediate circuits (13, 23, 33) by means of voltage sensors; and galvanically coupling intermediate circuits (13, 23, 33) of at least two test channels to form a common intermediate circuit or galvanically isolating the intermediate circuits (13, 23, 33) by means of a switching device (40) when the voltages in the intermediate circuits (13, 23, 33) reach a respective or a common predetermined threshold value Su.

13. Method according to claim 12, wherein the respective or common threshold Su is predetermined with respect to reaching a passive voltage level of the respective intermediate circuit (13, 23, 33) which is set in a balance of the voltage conversions of the respective test channel (10, 20, 30) in the uncontrolled invariable rectification itself.

14. Method according to any one of claims 11 or 13, further comprising the steps of: predetermining a predetermined time period after a completion of a switching operation for galvanic coupling or isolation of the DC links (13, 23, 33); and transferring the uncontrolled, invariable rectification to the phase-controlled, variably adjustable rectification by transferring the active power stages (12, 22, 32) from the passive operating mode back to the active operating mode when the predetermined time period has elapsed.

15. Method according to any one of claims 11 to 14, further comprising the intermediate step of: separating output stages (14, 24, 34) from an associated intermediate circuit (13, 23, 33), or separating test consumer devices (61, 62) from an associated output stage (14, 24, 34); and galvanic coupling of intermediate circuits (13, 23, 33) of at least two test channels to form a common intermediate circuit or galvanic isolation of the intermediate circuits (13, 23, 33) by means of a switching device (40) if a supply to all test consumer devices (61, 62) has been interrupted.