DE102022202360A1 - Circuit arrangement for generating an output direct voltage and use of the circuit arrangement for testing electrical energy storage devices - Google Patents

Abstract

The invention relates to a circuit arrangement (1) for generating at least one DC output voltage (2, 2a, 2b) based on an AC input voltage (3), having at least one input stage (4) and at least one rectifier (5), the input stage (4) can be connected to the input alternating voltage (3) and an intermediate circuit voltage can be generated with the input stage (4), and with the rectifier (5) producing at least a first direct voltage (6a, 6b) and at least a second direct voltage (7a, 7b) from the intermediate circuit voltage. can be generated, wherein the rectifier (5) has at least one double resonant stage (8, 8a, 8b) for generating the first direct voltage (6a, 6b) and the second direct voltage (7a, 7b). The invention also relates to the use of the circuit arrangement (1) for testing at least one electrical energy storage device.

Description

The present invention relates to a circuit arrangement for generating at least one DC output voltage based on an AC input voltage. The circuit arrangement has at least one input stage and at least one rectifier. The input stage can be connected to the input alternating voltage and at least one intermediate circuit voltage can be generated with the input stage. At least a first DC voltage and at least a second DC voltage can be generated from the intermediate circuit voltage using the rectifier.

The invention further relates to the use of a circuit arrangement for testing electrical energy storage devices.

Electronic circuits and assemblies are often operated with direct voltage. Usually several different potentials are required at the same time. In order for a supply from the AC voltage network to be possible, the AC voltage provided (AC input voltage) must first be converted into a corresponding output DC voltage using a circuit arrangement.

Known circuit arrangements usually include an input-side AC/DC converter with a single, usually relatively high DC voltage at the output, the so-called bus voltage, from which a downstream DC/DC converter generates the DC voltages required by the individual modules. The complexity of such topologies is sometimes quite high and/or they contain components that generate significant interference at the output. It is also suitable for special applications, e.g. B. testing electrical energy storage devices requires that negative output voltages can also be generated.

For many electronic devices, including test devices for testing electrical energy storage devices, statutory safety requirements also apply, according to which galvanic isolation of the supply side from the low-voltage network from external connections must be provided (e.g. DIN EN 61010 (Issue date 2020-03): Safety regulations for electrical measuring, control, regulation and laboratory devices).

It is generally known to implement the galvanic isolation at the input converter, the AC/DC converter, using an integrated or upstream transformer. The galvanic isolation can also take place in the DC/DC converter. For this purpose, DC/DC converters are usually used on the output side, but these become very expensive due to high performance. It is also known to use galvanic isolation from the transformer when connecting to the mains. It is also possible for an additional, separate transformer to be provided on the AC side.

DE 10 2014 013 039 A1 discloses, for example, a device for a motor vehicle for the galvanically decoupled transmission of an electrical voltage between a high-voltage circuit and a low-voltage circuit with a galvanically isolated DC-DC converter and a galvanically coupled DC-DC converter, which are connected in such a way that the galvanically isolated DC-DC converter converts a high-voltage DC voltage provided by the high-voltage circuit into a first DC voltage converts and the galvanically coupled DC-DC converter converts the first DC voltage into a second DC voltage.

US 2015/375628 A1 discloses a galvanic isolation charging device for an electric vehicle with a reversible AC/DC converter that allows two outputs to be powered at different voltages.

Also from US 2013/162032 A1 , US 2013/175990 A1 and DE 10 2017 208360 A1 Charging devices with galvanic isolation for an electric vehicle are known, with several converters being provided in each case.

DE 10 2012 212 291 A1 discloses a device for electrical direct current rapid charging or discharging of energy storage devices, comprising an AC/DC converter module coupled to an electrical supply network and a DC/DC converter module electrically coupled to the AC/DC converter module, wherein the DC/DC converter module has a DC/DC step-down converter module without galvanic isolation and a DC/DC resonant converter module for galvanic isolation.

As explained, test devices or test devices for testing electrical energy storage devices are also operated with direct voltage. There is therefore a particular need here for a circuit arrangement for generating an output direct voltage based on an input alternating voltage.

Mobile or stationary devices or electrical systems that are used to store electrical energy and release it again when needed are referred to as electrical energy storage devices. Such energy storage devices are based on chemical or physical effects and are often used in practice as batteries or capacitors executed. The properties of electrical energy storage devices are determined by test equipment. The tests are essentially based on supplying and removing electrical energy from the energy storage device. The measured values obtained characterize the properties of the energy storage device.

In particular, test systems are known here that quickly charge and discharge the energy storage devices by cyclically supplying and discharging direct current. The charging and discharging process takes place with high currents and with high dynamics to ensure storage systems, e.g. B. to investigate their suitability for battery electric vehicles (Battery Electric Vehicle BEV).

The power electronics used for this are usually located together with the measurement technology in an integrated test device. In addition to high electrical currents and high dynamics, the requirements for power electronics are that the direction of the current (charging/discharging) changes very quickly. Due to the partially low voltage of the test object, the required dynamics mean that the test device must also be able to provide a negative output voltage.

It is already known to use a high-frequency transformer that is controlled via active components. The active components generate a high-frequency alternating voltage, which is rectified again on the other side of the transformer with active components.

This topology, described in the literature as a “dual-active bridge”, operates a galvanically isolating high-frequency transformer in such a way that the output voltage can be varied via the active control of the rectifiers on the input and output sides. However, this topology hard switches the input and output currents on and off via the switching transistors. This switching behavior leads to undesirable interference due to strong switching pulses. The disruptions can be controlled through appropriate interference suppression measures in static operation at fixed operating points. However, a test system does not work at fixed operating points. Due to the dynamics of the tests, the operating point is constantly changing. This is a significant technical disadvantage of a dual active bridge topology. The interference that occurs is both detrimental to the accuracy of the measurements and problematic in terms of eliminating interference.

Based on the above prior art, the present invention is based on the object of providing a circuit arrangement with which electrical energy storage can be tested and with which at least one, in particular also negative, output direct voltage can be generated from an input alternating voltage.

According to the invention, this object is achieved by a circuit arrangement with the features of claim 1.

Accordingly, the circuit arrangement for generating at least one DC output voltage based on an AC input voltage has at least one input stage and at least one rectifier. The input stage can be connected to the input alternating voltage and an intermediate circuit voltage can be generated with the input stage. With the rectifier, at least a first DC voltage and at least a second DC voltage can be generated from the intermediate circuit voltage.

The circuit arrangement is characterized in that the rectifier has at least one double resonant stage for generating the first direct voltage and the second direct voltage.

The intermediate circuit voltage refers to the voltage in the intermediate voltage level in front of the rectifier, which is different from the alternating input voltage. In the circuit arrangement, the voltage conversion takes place in a multi-stage process.

The advantage of the circuit arrangement according to the invention is that a direct output voltage can be generated or several different output direct voltages can be generated, which are automatically adjusted via the transmission ratio. The double resonant stage ensures very good EMC and interference behavior without voltage peaks due to switching at the zero point. In addition, the double resonant stage enables a small design for galvanic isolation, which requires little space and has little mass.

A first embodiment of the circuit arrangement provides that the rectifier is designed as an LLC resonance converter. This means that on the transformer primary side, a series resonant circuit consisting of the transformer, an inductor and an additional capacitor is connected together, which generates a sinusoidal wave (instead of square-wave pulses). This series resonant circuit is also called a resonance tank.

The LLC resonance converter preferably has at least two resonance converter stages that are known per se in terms of circuitry. Any Reso nance converter stage has a resonance tank connected to the primary side of a transformer, with two resonance converter stages being interconnected to generate the first DC voltage and the second DC voltage.

The at least one double resonant stage is formed from two resonance converter stages and therefore preferably each has a first LLC stage and a second LLC stage parallel to it. The LLC stages each include at least the resonance tank with the transformer and a secondary-side converter topology.

Preferably at least two double resonant stages are present. There are preferably 3 to 64 double resonant stages present. In particular, there are 6 double resonant stages. It is also envisaged that more than 64 double resonant stages are arranged.

According to a further preferred embodiment, the first LLC stage has a first capacitor, a first inductor and a first transformer. The second LLC stage includes a second capacitor, a second inductor and a second transformer. The basic principle of this resonance converter is based on the fact that the primary driver winding of the first converter transformer together with the first capacitor and the first inductor forms a first LC series resonant circuit, and the primary driver winding of the second converter transformer together with the second capacitor and the second inductor forms a second LC Series resonant circuit forms.

It is preferred that the rectifier or the LLC resonant converter has at least one front-end H-bridge fed with the intermediate circuit voltage for rectifying the input alternating voltage and the at least one double resonant stage. The AC side of the H-bridge is connected to the primary side of the first transformer via the series connection of the first capacitor and first inductor of the first LLC stage and is connected to the primary side of the second transformer via the series connection of the second capacitor and second inductor of the second LLC stage . In this way, the rectified input alternating voltage can be transferred to the first and second transformers.

Furthermore, it is preferred that the secondary side of the first transformer and the secondary side of the second transformer are connected in such a way that the first DC voltage can be generated with the first LLC stage, and that the second DC voltage can be generated with the second LLC stage.

According to a preferred embodiment of the rectifier, the secondary side of the first transformer and the secondary side of the second transformer each have a full bridge rectifier circuit. Preferably, the full bridge rectifier circuits each have four transistors as switching elements, which are connected to the respective secondary winding in a manner known per se to generate the first or second direct voltage.

According to an alternative embodiment of the rectifier, the first and/or the second transformer has a multiple winding, preferably a series-connected multiple winding, in particular a double winding, on the secondary side. In this embodiment it is provided that the secondary side of the first transformer and the secondary side of the second transformer each have a half-bridge rectifier circuit with two transistors each, which are connected to the respective secondary winding in a manner known per se to generate the first and second direct voltage.

A second embodiment of the circuit arrangement also provides a rectifier with at least two resonance converter stages. In contrast to the first embodiment described above, only the series resonant circuit consisting of transformer, inductor and capacitor is formed on the secondary side of the transformer and not on the primary side.

Analogous to the first embodiment, each resonance converter stage therefore has a resonance tank connected to the secondary side of a transformer and a converter topology that is known per se. Two resonance converter stages are interconnected to generate the first direct voltage and the second direct voltage. The at least one double resonant stage of the second embodiment is therefore formed from two resonance converter stages and preferably each has a first LLC stage and a second LLC stage.

A third embodiment of the circuit arrangement also provides a rectifier with at least two resonance converter stages. In contrast to the second embodiment described above, only one transformer with a multiple winding on the secondary side is provided, with the respective series resonant circuit being coupled to the first or second secondary winding.

A further embodiment of the circuit arrangement provides that at least one DC-DC converter is connected downstream of the rectifier is. The DC-DC converter is arranged and connected to the rectifier or to its outputs in such a way that at least one variable output DC voltage can be generated from the first and second DC voltage.

Preferably, the DC-DC converter is designed and set up in such a way that the output DC voltage can be varied between a value of the negative first DC voltage and the positive second DC voltage, e.g. B. between -10 V to 20 V.

The advantage of this configuration is that the output voltage can be reversed, i.e. a negative output voltage can be generated, e.g. B. of -10 V, which allows testing of memory cells, e.g. B. which have a voltage of 2 V to 7 V.

The DC-DC converter is preferably designed as a buck boost stage or as a linearly regulated output stage or as a buck stage, each double resonant stage preferably having at least one buck boost stage or at least one linearly regulated output stage or at least one buck stage.

This advantageously enables the circuit arrangement and thus also the galvanic isolation to work bidirectionally and to have a high dynamic control behavior, both for the current and power dynamics as well as for the direction of the energy flow (charging/discharging).

Bidirectional means that, for example, energy taken from a test object can be recovered and fed back into the supply network. In particular, larger energy storage systems can be tested without releasing the extracted energy as lost energy.

In the case of a DC-DC converter designed as a buck boost stage, it is also preferred that the buck boost stage is connected to the first DC voltage via a first switching element, in particular a first transistor, and to the second DC voltage via a second switching element, in particular a second transistor. The DC output voltage is then provided via at least one capacitor connected in series with at least one storage inductor. The storage choke is preferably also connected in series with a current measuring shunt. This enables advantageous regulation of the output current and output voltage. The storage choke is a coil for storing energy. The current measuring shunt is a low-resistance electrical measuring resistor.

Preferably, the first direct voltage and the second direct voltage are each below 100 V, in particular below 50 V, preferably below 20 V, particularly preferably in the range from approximately 10 V to 20 V.

Preferably the input AC voltage is between 100 V and 690 V.

According to a preferred embodiment, the input stage is designed and set up in such a way that an intermediate circuit voltage of 300 V to 1200 V, preferably 800 V, can be generated.

Furthermore, the input stage is preferably designed as a power factor controller. This advantageously places less strain on the supply network and also results in less reactive current and mains current harmonics, which can cause unacceptable distortion of the mains voltage.

Furthermore, it is the object of the present invention to provide a possibility for testing electrical energy storage devices.

According to the invention, this object is achieved with the feature content of claim 16 in that the circuit arrangement according to the invention is used for testing electrical energy storage devices.

The circuit arrangement according to the invention can be used for testing a single energy storage device or for testing several or a large number of energy storage devices connected in parallel to the circuit arrangement.

The energy storage preferably has at least one primary battery, at least one secondary battery, at least one single cell, at least one half cell or at least one supercapacitor.

• 1 einen Schaltplan eines Ausführungsbeispiels einer erfindungsgemäßen Schaltungsanordnung;
• 2 den Schaltplan eines Ausführungsbeispiels mit zusätzlichem Gleichspannungswandler;
• 3 den Schaltplan eines Ausführungsbeispiels mit mehreren doppelt resonanten Stufen;
• 4 den Schaltplan eines alternativen Ausführungsbeispiels einer erfindungsgemäßen Schaltungsanordnung mit Halbbrückengleichrichtern;
• 5 den Schaltplan eines weiteren Ausführungsbeispiels einer erfindungsgemäßen Schaltungsanordnung mit sekundärseitigem Resonanztank;
• 6 den Schaltplan eines weiteren Ausführungsbeispiels einer erfindungsgemäßen Schaltungsanordnung mit lediglich einem Transformator und sekundärseitigem Resonanztank.

Further advantageous embodiments of the invention result from the following description of the figures and the dependent subclaims. Show it:

• 1 a circuit diagram of an exemplary embodiment of a circuit arrangement according to the invention;
• 2 the circuit diagram of an exemplary embodiment with an additional DC-DC converter;
• 3 the circuit diagram of an embodiment with several double resonant stages;
• 4 the circuit diagram of an alternative embodiment of a circuit arrangement according to the invention with half-bridge rectifiers;
• 5 the circuit diagram of a further exemplary embodiment of a circuit arrangement according to the invention with a secondary-side resonance tank;
• 6 the circuit diagram of a further exemplary embodiment of a circuit arrangement according to the invention with only one transformer and a resonance tank on the secondary side.

In the various figures of the drawing, the same parts are always provided with the same reference numbers.

The following description claims that the invention is not limited to the exemplary embodiments and not to all or several features of the combinations of features described, but rather each individual partial feature of the/each exemplary embodiment is also detached from all other partial features described in connection therewith also in combination with any features of another exemplary embodiment of importance for the subject matter of the invention.

1 shows the circuit diagram of an exemplary embodiment of a circuit arrangement 1 according to the invention for generating at least one output direct voltage based on an input alternating voltage 3. The circuit arrangement 1 has at least one input stage 4 and at least one rectifier 5.

The input stage 4 is connected to the input alternating voltage 3 and serves to provide an intermediate circuit voltage for the rectifier 5. The input stage 4 is preferably a bidirectional AC/DC power supply, e.g. a 10 kW power factor correction stage (PFC stage) 12 with a parallel output capacitor, which provides the intermediate circuit voltage of around 800 V.

The rectifier 5 is connected to the output of the input stage 4 or to its output capacitor. The rectifier 5 has a front-end H-bridge H1 and a double-resonant converter stage 8.

The H-bridge H1 is connected on the input side to the output of input stage 4. The H-bridge H1 is designed in the usual way. There are four transistors Q1-Q4. Transistors Q1 and Q2 have their drain connections at a first output of the input stage 4. Transistors Q3 and Q4 have their source connections at a second output of the input stage 4. Source of Q1 and Q2 are connected to drain of Q3 and Q4 respectively.

The double resonant converter stage 8 has a galvanically isolated first and second LLC stage 9a, 9b with a first output H-bridge H2 and a second output H-bridge H3 on the secondary side.

The LLC stages 9a, 9b each have a resonance tank made of a series-connected capacitor C1, C2 and an inductor L1, L2 on the primary side on the positive polarity of a transformer T1, T2. The resonance tank is respectively connected to the input side transistors Q1 and Q3 of the H-bridge H1 and the negative polarity of the transformer T1, T2 is respectively connected to the transistors Q2 and Q4 of the H-bridge H1.

The first output H-bridge H2 and the second output H-bridge H3 are provided on the secondary side of the transformer T1, T2. The output H-bridges H2, H3 are designed in the manner known per se of a full-bridge rectifier. There are four transistors Q1-Q4 each. The transistors Q1 with source and Q3 with drain are connected to the positive polarity of the transformer T1, T2. The negative polarity is connected to source of transistor Q2 and drain of transistor Q4. The drain connections of Q1 and Q2 are connected to each other and to an output capacitor each. The drains of Q3 and Q4 are also connected to each other and to the second end of the respective output capacitor.

It goes without saying that the transistors designated Q1-Q4 in the H-bridges H1, H2, H3 can each be designed identically or differently. The transistors Q1-Q4 are preferably selected according to the level of the individual intermediate circuit voltage. This achieves an efficiency optimization of the individual H-bridges H1, H2, H3, which is advantageous for the thermal balance and the size of the device.

2 shows a circuit diagram of a further exemplary embodiment of a circuit arrangement 1. The circuit arrangement 1 essentially corresponds to the exemplary embodiment 1 , where according to 2 an additional DC-DC converter 10 in the form of a buck boost stage 11 is provided at the output of the rectifier stage 5. For the construction of the input stage 4 and the rectifier 5, see the explanations 1 referred.

The buck boost stage 11 has two switching elements Q7 and Q8 designed as transistors as well as a storage choke L3, a measuring shunt R1 and an output capacitor C3.

The transistor Q7 with a drain is connected to a first output terminal of the rectifier 5. The transistor Q8 is connected to the second output terminal of the rectifier 5 with source. The source of the transistor Q7 and the drain of the transistor Q8 are connected to each other and to a first output terminal of the buck boost stage 11 via the storage inductor L3 and the measuring shunt R1 connected in series. The second output connection of the buck boost stage 11 is connected between the two output capacitors of the rectifier 5. The buck-boost capacitor C3 is connected in parallel to the output terminals of the buck boost stage 11.

3 shows the circuit diagram of a further exemplary embodiment of a circuit arrangement 1, which is essentially according to 2 is formed, but two double resonant stages 8a, 8b are provided. Accordingly, the circuit arrangement 1 according to this embodiment also has two buck boost stages 11, with one buck boost stage 11 being connected to a double resonant stage 8a, 8b. The details of the electrical connection can be found in the description of the exemplary embodiment 2 referred. The two double resonant stages 8a, 8b are constructed in the same way and connected to the H-bridge H1 as above 2 for which a double resonant stage 8 is described.

A first and second direct voltage 6a, 7a can be generated with the first double resonant stage 8a. With the second double resonant stage 8b, a further first and second direct voltage 6b, 7b can be generated independently. With the subsequent buck boost stages 11, two independent output voltages 2a, 2b can be generated, analogous to the explanation above.

4 shows the circuit diagram of a further, alternative embodiment of the circuit arrangement 1 according to the invention. The circuit arrangement 1 according to this alternative has as in 1 an input stage 4 and a rectifier 5. The input stage 4 corresponds to the input stage 4 in 1 .

The rectifier 5 differs from the rectifier 5 of the exemplary embodiment 1 in that two half-bridge rectifiers are provided on the secondary side of the transformers instead of the two full-bridge rectifiers. A first transformer T3 and a second transformer T4 each have a series-connected double winding on the secondary side, which is connected to a first and second transistor Q5, Q6 on each side.

The half-bridge rectifier is designed in a manner known per se, i.e. H. The source connection of the first transistor Q5 is present at the first end of the transformer T3, T4 or at the positive polarity of the first winding. The source connection of the second transistor Q6 is present at the second end of the transformer T3, T4 or at the negative polarity of the second winding. Drain of the first transistor Q5 is connected to the drain of the second transistor Q6 and to an output capacitor. The other terminal of the output capacitor is connected between the first and second windings to the transformers T3 and T4, respectively. The first or second output DC voltage 6a, 7a is present at the output capacitors.

5 shows the circuit diagram of a further exemplary embodiment of the circuit arrangement 1 according to the invention. This circuit arrangement 1 has as in 1 an input stage 4 and a rectifier 5 with a double resonant stage 8. Input level 4 corresponds to input level 4 off 1 . The rectifier 5 differs from that of the exemplary embodiment 1 only because the resonance tank 9a, 9b of the respective double resonant stage 8 is located on the secondary side of the transformer T1, T2.

The execution according to 5 is with the DC-DC converter 10, in particular the buck boost stage 11, according to 2 and/or can be combined with several double resonant stages and/or as a half-bridge rectifier 4 executable.

6 shows the circuit diagram of a further exemplary embodiment of the circuit arrangement 1 according to the invention. In contrast to 1 - 5 Only one transformer T5 is provided here. The resonance tanks 9a, 9b are located as in 5 on the secondary side. The transformer T5 has two secondary windings for supplying the resonance tanks 9a and 9b. Otherwise the circuit is as in 5 executed. The direct voltages 6a and 7a can be adjusted individually via the number of turns of the two secondary windings.

Reference numeral-.

1

Circuit arrangement

2, 2a, 2b

DC output voltage

3

AC input voltage

4

Entrance stage

5

rectifier

6a, 6b

first direct voltage

7a, 7b

second direct voltage

8, 8a, 8b

double resonant stage

9a

first LLC level

9b

second LLC tier

10, 10a, 10b

DC-DC converter

11

Buck Boost level

12

PFC input stage

C

capacity

L

inductance

H

H-bridge

Q

transistor

R

Resistance

T

transformer

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014013039 A1 [0007]
• US 2015375628 A1 [0008]
• US 2013162032 A1 [0009]
• US 2013175990 A1 [0009]
• DE 102017208360 A1 [0009]
• DE 102012212291 A1 [0010]

Non-patent literature cited

• DIN EN 61010 [0005]

Claims (17)

Circuit arrangement (1) for generating at least one DC output voltage (2, 2a, 2b) based on an AC input voltage (3), comprising at least one input stage (4) and at least one rectifier (5), the input stage (4) being connected to the AC input voltage ( 3) can be connected and an intermediate circuit voltage can be generated with the input stage (4), and at least a first DC voltage (6a, 6b) and at least a second DC voltage (7a, 7b) can be generated with the rectifier (5) from the intermediate circuit voltage, thereby characterized in that the rectifier (5) has at least one double resonant stage (8, 8a, 8b) for generating the first direct voltage (6a, 6b) and the second direct voltage (7a, 7b). Circuit arrangement (1) according to Claim 1 , characterized in that the rectifier (5) is designed as an LLC resonance converter. Circuit arrangement (1) according to one of the preceding claims, characterized in that the double resonant stage (8, 8a, 8b) each has a first LLC stage (9a) and a second LLC stage (9b) parallel thereto. Circuit arrangement (1) according to Claim 3 , characterized in that the first LLC stage (9a) has a first capacitor (C1), a first inductor (L1) and a first transformer (T1, T3), and the second LLC stage (9b) has a second capacitor ( C2), a second inductor (L2) and a second transformer (T2, T4). Circuit arrangement (1) according to Claim 4 , characterized in that the rectifier (5), in particular the LLC converter, has at least one front-end H-bridge fed with the intermediate circuit voltage and the at least one double resonant stage (8, 8a, 8b), the AC side of the H-bridge is connected to the primary side of the first transformer (T1, T3) via the series-connected first capacitor (C1) and the first inductance (L1) of the first LLC stage (9a) and via the series-connected second capacitor ( C2) and the second inductor (L2) of the second LLC stage (9b) is connected to the primary side of the second transformer (T2, T4). Circuit arrangement (1) according to Claim 4 , characterized in that the rectifier (5), in particular the LLC converter, has at least one front-end H-bridge fed with the intermediate circuit voltage and connected to the first and second transformers (T1, T2), the one connected in series first capacitor (C1) and the first inductor (L1) of the first LLC stage (9a) are provided on the secondary side of the first transformer (T1) and the series-connected second capacitor (C2) and the second inductor (L2) of the second LLC stage (9b) is provided on the secondary side of the second transformer (T2). Circuit arrangement (1) according to Claim 5 or 6 , characterized in that the secondary side of the first transformer (T1, T3) and the secondary side of the second transformer (T2, T4) are connected in such a way that the first DC voltage (6a, 6b) can be generated with the first LLC stage (9a). , and that the second DC voltage (7a, 7b) can be generated with the second LLC stage (9b). Circuit arrangement (1) according to Claim 7 , characterized in that the secondary side of the first transformer (T1) and the secondary side of the second transformer (T2) each have a full bridge rectifier circuit, preferably each with four transistors (Q1-Q4), or that the first transformer (T3) and / or the second transformer (T4) has multiple windings, preferably a series-connected multiple winding, in particular double winding, on the secondary side, and the secondary side of the first transformer (T3) and the secondary side of the second transformer (T4) each have a half-bridge rectifier circuit. Circuit arrangement (1) according to Claim 3 , characterized in that the rectifier (5) has a transformer (T5) with a series-connected multiple winding, in particular double winding, on the secondary side and at least one front-end H-bridge fed with the intermediate circuit voltage and connected to the transformer (T5). has, wherein the first LLC stage (9a) has a series-connected first capacitor (C1) and a first inductor (L1), which are coupled to a first secondary winding of the transformer (T5), and the second LLC stage (9b ) has a series-connected second capacitor (C2) and a second inductor (L2), which are coupled to a second secondary winding of the transformer (T5), the two secondary windings preferably being connected in such a way that with the first LLC stage (9a ) the first DC voltage (6a) can be generated, and that the second DC voltage (7a) can be generated with the second LLC stage (9b). Circuit arrangement (1) according to one of the preceding claims, characterized in that at least one DC-DC converter (10, 10a, 10b) is also present, and that the DC-DC converter (10, 10a, 10b) is arranged in such a way that at least one variable output direct voltage (2, 2a, 2b) can be generated, in particular that the output direct voltage (2, 2a, 2b) is between a value of the positive first direct voltage (6a, 6b) and the negative second direct voltage (7a , 7b) can be varied. Circuit arrangement (1) according to Claim 10 , characterized in that the DC-DC converter (10, 10a, 10b) is designed as a buck boost stage (11) or as a linearly regulated output stage or as a buck stage, each double resonant stage (8, 8a, 8b) preferably being a buck boost stage (11) or linearly regulated output stage or buck stage. Circuit arrangement (1) according to Claim 11 , characterized in that the buck boost stage (11) via a first switching element (Q7), in particular a transistor, with the first direct voltage (6a, 6b) and via a second switching element (Q8), in particular a transistor, with the second direct voltage (7a , 7b), and wherein the DC output voltage (2, 2a, 2b) is provided via at least one capacitor (C3) connected in series with at least one storage choke (L3), the storage choke (L3) preferably being connected in series with a current Measuring shunt (R1) is switched on. Circuit arrangement (1) according to one of the preceding claims, characterized in that at least two double resonant stages (8, 8a, 8b) are present, preferably that 3 to 64 double resonant stages (8, 8a, 8b) are present, in particular, that there are 6 double resonant stages (8, 8a, 8b). Circuit arrangement (1) according to one of the preceding claims, characterized in that the first and second direct voltage (6a, 6b, 7a, 7b) are below 100 V, in particular below 50 V, preferably below 20 V, particularly preferably in the range 10 V to 20 V, and/or that the input AC voltage is between 100 V and 690 V. Circuit arrangement (1) according to one of the preceding claims, characterized in that the input stage (4) is designed and set up in such a way that the intermediate circuit voltage can be generated with 300 V to 1200 V, preferably 800 V, wherein preferably the input stage (4) as Power factor controller is designed. Use of the circuit arrangement (1) according to one of the preceding claims for testing at least one electrical energy storage device. Use after Claim 16 , characterized in that the energy storage has at least one primary battery, at least one secondary battery, at least one single cell, at least one half cell or at least one supercapacitor.

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