DE102014005124A1 - Circuit arrangement and method for exchanging electrical energy - Google Patents

Abstract

Circuit arrangement for exchanging electrical energy between at least one DC voltage source (B) and / or sink on the one hand and at least one AC voltage sink and / or source on the other hand, with a two-part DC-DC converter (10; 10 ') for connecting the circuit arrangement (1; 1 ', 1' ', 1' '') to the positive and negative poles of the DC voltage source (B) and / or sink, with an inverter (30; 30 '; 30' '; 30' '; 30A'; 30A 30B '; 30B' '; 30C'; 30C '') for at least four potential points having at least one phase (31, 32, 33) for connecting the circuit arrangement (1; 1 '; 1' '; 1' '' ) to the AC voltage sink and / or source and to an at least three-part voltage intermediate circuit (20; 20 ') connected between the two-part DC-DC controller (10; 10') and the inverter (30; 30 '; 30' '; 30 ''; 30A '; 30A' '; 30B'; 30B ''; 30C '; 30C' ').

Description

The invention relates to a circuit arrangement and a method for exchanging electrical energy between a DC voltage source and / or sink on the one hand and an AC voltage sink and / or source on the other hand.

The invention relates to a sub-field of electrical engineering, especially the power electronics. The power electronics generally involve the conversion of electrical energy by changing voltage, current and / or frequency. In particular, the invention relates to a targeted energy exchange between one or more DC voltage sources and / or sinks and one or more phase AC voltage sources and / or sinks. Batteries, capacitors, in particular double-layer capacitors, solar cells and / or fuel cells can be used as DC voltage sources and / or lower. As AC voltage sink and / or source, an AC mains or three-phase network or a corresponding island network can be provided. In addition, three-phase or multi-phase electrical machines are possible as sources / sinks.

The invention is intended for a power range of energy conversion that can convert energy levels from a few kilowatts to several megawatts. In particular, the invention is intended for electrical circuits in the low voltage and medium voltage range.

From the document DE 10 2009 047 936 A1 An inverter is known with which a present DC voltage can be converted into an AC voltage. In this case, a DC voltage source is connected via a boost converter to a two-part voltage intermediate circuit. A three-state inverter controls the supply of electrical energy from the two-part voltage intermediate circuit in an AC network. In this case, the two-part boost converter must be designed at its input to a voltage range of 0 to 100% of the voltage of the DC voltage source. Furthermore, an energy transfer only from the DC voltage source to the AC network is possible.

The invention has for its object to provide an improved energy exchange between a DC voltage source and / or sink and an AC voltage sink and / or source. The improvement may be, for example, that cheaper electrical components can be used and / or energy transfer in both directions is possible.

This object is solved by the subject matters of the independent claims. Preferred embodiments are the subject matters of the dependent claims.

• – einem zweigeteilten DC-DC-Steller zum Anschluss der Schaltungsanordnung an den Plus- und Minuspol der Gleichspannungsquelle und/oder -senke,
• – einem Wechselrichter für zumindest vier Potentialpunkte mit zumindest einer Phase zum Anschluss der Schaltungsanordnung an die Wechselspannungssenke und/oder -quelle und
• – einem zumindest dreiteiligen Spannungszwischenkreis, der zwischen den zweigeteilten DC-DC-Steller und den Wechselrichter geschaltet ist.

According to one aspect, the invention relates to a circuit arrangement for exchanging electrical energy between at least one DC voltage source and / or sink on the one hand and at least one AC voltage sink and / or source on the other hand with:

• A two-part DC-DC controller for connecting the circuit arrangement to the positive and negative poles of the DC voltage source and / or sink,
• - An inverter for at least four potential points with at least one phase for connection of the circuit arrangement to the AC voltage sink and / or source and
• - An at least three-part voltage intermediate circuit, which is connected between the two-part DC-DC controller and the inverter.

The circuit arrangement can be provided and designed to exchange electrical energy in both directions, ie in the direction of the DC voltage side and / or in the direction of the AC voltage side. Alternatively, the circuit arrangement can also be provided and designed for the energy exchange in only one predetermined direction.

The circuit arrangement can be designed to exchange electrical energy between a plurality of DC voltage sources and / or sinks on the DC side. For example, multiple strings of solar cells can be connected and operated at individual points of maximum power. Each individual DC source can be connected via several parallel DC-DC controllers. Any combinations are possible here. Furthermore, the circuit arrangement can also be formed on the alternating voltage side for the connection of a plurality of alternating voltage sinks and / or sources.

The two-part DC-DC controller is formed at least two parts, which means that the two-part DC-DC controller has at least two circuit parts as half-bridges, of which one circuit part is associated with the positive pole and one of the negative pole of the DC voltage source and / or sink or electrically connected thereto. The half bridges can be further divided and have further subcomponents. In particular, the two-part DC-DC controller may have two or more independent DC-DC controller as its two circuit parts, ie at least one DC-DC controller for each half-bridge. The two-part DC-DC controller can be clocked have controllable switch, which control the current flow between the DC voltage source and / or sink and the three-part voltage intermediate circuit and / or regulate.

The inverter for at least four potential points is designed at least as a 4-point inverter. The inverter is designed and provided to control and / or regulate the current flow and the energy flow between four different potential points of the three-part voltage intermediate circuit and the AC voltage sink and / or source. The inverter can for this purpose have electrical switches, which are clocked by, for example, a pulse width modulation can be controlled.

The at least three-part voltage intermediate circuit is designed and provided to temporarily store and / or divide electrical energy between the DC voltage side and the AC voltage side into three circuit parts of the three-part voltage intermediate circuit. Each of these three circuit parts can for this purpose have at least one buffer, such as a capacitor. The three-part voltage intermediate circuit can provide and / or have the four electrical potential points for the inverter. The four electrical potential points can all differ from each other, that is to say lie on a respectively different electrical potential.

The circuit arrangement can either have only connections for the DC voltage source and / or sink or also comprise the DC voltage source and / or sink. The same applies to the AC side: The circuit may either have only connections for the AC voltage sink and / or source or include the AC voltage sink and / or source. The respective terminals may be formed as inputs, as outputs or as inputs and outputs of the circuit arrangement.

The amount of DC voltage of the DC voltage source and / or sink can be less than twice the amplitude of the AC voltage, since the power electronic circuit arrangement allows adaptation to a variable level of the DC voltage for the energy exchange. The AC voltage may be constant or variable both in frequency and in amplitude. Furthermore, the feeding of electric machines with three or more phases can be easily implemented by the circuit arrangement, since the circuit arrangement provides a variable in amplitude and frequency voltage system.

The tripartite voltage intermediate circuit is designed and provided as an energetic interface between the two-part DC-DC controller and the inverter. The two-part DC-DC controller allows an energy exchange between the DC side and the shared voltage intermediate circuit.

Depending on the design, an energy exchange between the DC side and the AC side can be done in one or both directions. The inverter for the at least four potential points allows an energy exchange over four potential points (also called level, poles or stages as in a multi-stage inverter) with the two-part DC-DC controller via the voltage intermediate circuit. The inverter for the at least four potential points generates a voltage curve with higher quality or lower harmonics than two-point or three-point inverters. For balancing the energies in the capacitors, it is advantageous if the four-point inverter is supplied by all four potentials from the DC side, instead of supplying it only via the two external potentials. This improves the quality of the AC voltage in comparison to two-pole supplied inverters.

By dividing the voltage intermediate circuit into at least three parts, the circuit arrangement allows the use of less expensive power electronics components in the two-part DC-DC controller, since the individual components only have to be designed for only fractions of the voltage of the DC voltage source and / or sink. In one embodiment, the two-part DC-DC controller is only designed for a maximum of 70%, preferably for a maximum of 60%, particularly preferably for a maximum of 50%, furthermore particularly preferably for a maximum of 30% of the DC voltage. In contrast, the components of the power electronics according to the prior art must be designed for 0 to 100% of the voltage of the DC side. This reduces the overall cost of the power exchange circuitry between a DC side and an AC side.

According to one embodiment, the two-part DC-DC controller controls and / or regulates the exchange of electrical energy between the DC voltage source and / or sink and the three-part voltage intermediate circuit. The term "control and / or regulate" encompasses the English term "controlling".

According to one embodiment, a first circuit part of the two-part DC-DC adjuster is electrically connected to the negative terminal of DC source and / or sink connected, and a second circuit part of the two-part DC-DC adjuster is electrically connected to the positive pole of the DC voltage source and / or sink. The first and second circuit part of the two-part DC-DC adjuster are each designed and provided for controlling and / or regulating the current flow and energy flow between the respective pole of the DC voltage side and a potential point of the three-divided voltage intermediate circuit.

According to one embodiment, a first circuit part and a second circuit part of the two-part DC-DC adjuster each have a boost converter, a buck converter or a boost / buck converter. The two-part DC-DC controller is thus formed as a circuit element with two independently controllable, for example, circuit parts, which are each designed as an independent DC-DC controller. The two circuit parts of the two-part DC-DC controller may have further elements and / or be further subdivided. Depending on whether the circuit parts of the two-part DC-DC controller are designed as a boost converter or buck converter or a high-buck converter, the circuit itself is suitable only for energy exchange in one direction (ie, for example, from the DC voltage side to AC side or vice versa ) or in both directions.

In a further development of this embodiment, the first circuit part and the second circuit part of the two-part DC-DC controller are formed symmetrically to each other and have the same, corresponding to each other circuit elements. In this case, the two circuit parts can in particular be of identical design, for example as two identical low plates, high plates or high-low plates. The two circuit parts may also be constructed asymmetrically with respect to one another, so that the first circuit part is provided and designed for connection to the negative pole of the DC voltage side, while the second circuit part is designed and provided for connection to the positive pole of the DC voltage side.

According to one embodiment, the three-part voltage intermediate circuit has at least three capacitors connected in series. Furthermore, the three-part voltage intermediate circuit respectively between the series-connected capacitors and at the two outer ends of the at least three series-connected capacitors electrical potential points for contacting both by the two-part DC-DC controller and by the inverter. Thus, at least four different potential points are provided by the three-part voltage intermediate circuit. The three capacitors can be designed in several parts, so that a single one of the three capacitors also two or more z. B. in series or in parallel capacitors may have. The three series-connected capacitors serve as a buffer for temporarily storing the electrical energy on the way from the DC side to the AC side and / or vice versa.

In a development of this embodiment, a minus capacitor of the three-part voltage intermediate circuit is assigned to the negative pole of the DC voltage source and / or sink via a first circuit part of the two-part DC-DC controller. A positive capacitor of the three-part voltage intermediate circuit is assigned to the positive pole of the DC voltage source and / or drain via a second circuit part of the two-part DC-DC controller. A center capacitor is connected in series with and between the negative capacitor and the plus capacitor. The negative capacitor, the positive capacitor and the mid-condenser form the three series-connected capacitors of the three-part voltage intermediate circuit. 'Assigned' may mean that the first or second circuit part controls and / or regulates the current flow and energy flow from or to the pole of the DC voltage source and / or sink to or from the respective capacitor. By the first and second circuit part can be controlled and / or regulated in particular, with which side of the respective capacitor of the respective pole of the DC voltage source and / or sink is connected.

In a development of this embodiment, the DC voltage source and / or sink has an average potential. In this case, the middle capacitor of the three-part voltage intermediate circuit is formed in two parts, wherein the middle potential of the DC voltage source and / or sink is electrically connected between the two-part center capacitor. The negative capacitor and the positive capacitor and the two associated first and second circuit parts of the two-part DC-DC controller are arranged symmetrically to the center potential and formed. In this case, the inverter, if it is formed, for example, single-phase, control the AC voltage to the center potential and / or regulate.

In the embodiment with the three capacitors connected in series, the inverter can be designed and provided to modulate the electrical potential at respectively one of the four potential points of the three-divided voltage intermediate circuit and / or from a phase voltage of the AC voltage of the AC voltage sink and / or source. A corresponding phase circuit of the inverter can thus be used as output and / or input for the current on the AC voltage side formed and provided. The inverter controls and / or regulates the electrical connection between the four potential points of the tripartite voltage intermediate circuit and to the current or voltage inputs and / or outputs of the circuit arrangement on the AC side. The inverter may further comprise electronic switches, which may be clocked, for example, by means of a pulse width modulation so that the desired AC voltage or DC voltage results. The switches can be designed as power electronic components.

According to one embodiment, the inverter controls and / or regulates an electrical contact between electrical potential points of the three-part voltage intermediate circuit and the AC voltage sink and / or source. This can be done for example by a pulse width modulation.

According to one embodiment, the inverter modulates the voltage at electrical potential points of the three-part voltage intermediate circuit by means of a pulse width modulation to an AC output voltage for the AC voltage sink. Alternatively or additionally, the inverter can modulate an input AC voltage of the AC voltage source as a PWM signal and apply it to electrical potential points of the three-part voltage intermediate circuit.

The term modulate may include a "demodulate".

According to one embodiment, the inverter is biphasic and modulates an AC voltage as the sum of two phase voltages at two of its phase circuit parts. Alternatively, the inverter may be three-phase formed with three phase circuit parts and modulate an AC voltage on the three phase voltage circuit parts. For the supply of energy in an AC voltage network or for the formation of an AC voltage at the output of the circuit arrangement of the inverter is preferably one or two-phase design. For the supply of energy in a three-phase network, for the supply of a three-phase machine or generally for the formation of a three-phase voltage system, the inverter is preferably formed three-phase. In industrial machines and / or machines in the automotive sector with more than three electrical phases, the inverter can be formed extended by a corresponding number of phase-switching parts.

In one embodiment, the inverter is designed as a 4-point inverter, a 2 × 2-point inverter, a 2 × 3-point inverter or a 1 × 3-point inverter in combination with a 1 × 2-point inverter , In any case, the inverter is designed and provided to control and / or regulate at least four different potential points. In particular, the inverter z. B. as a 4-level diode-clamped inverter, as a 4-level T-type inverter, as a 4-level multi-point clamped inverter or a 4-level active-neutral-point-clamped inverter.

• – ein zweigeteilter DC-DC-Steller die elektrischen Verbindungen zwischen dem Plus- und dem Minuspol der Gleichspannungsquelle und/oder -senke einerseits und elektrischen Potentialpunkten eines dreiteiligen Spannungszwischenkreises andererseits steuert und/oder regelt und
• – ein Wechselrichter die elektrischen Verbindungen zwischen der Wechselspannungssenke und/oder -quelle den elektrischen Potentialpunkten des dreiteiligen Spannungszwischenkreises steuert und/oder regelt.

One aspect relates to a method for exchanging electrical energy between at least one DC voltage source and / or sink on the one hand and at least one AC voltage sink and / or source on the other hand, wherein

• - A two-part DC-DC controller controls the electrical connections between the positive and negative poles of the DC voltage source and / or sink on the one hand and electrical potential points of a three-part voltage intermediate circuit on the other hand and / or regulates and
• - An inverter controls the electrical connections between the AC voltage sink and / or source the electrical potential points of the three-part voltage intermediate circuit and / or regulated.

By means of the method, the circuit arrangement according to the first aspect can be controlled.

The invention will be explained in more detail with reference to embodiments shown in FIGS. Individual features of the embodiments shown in the figures may be combined with other embodiments shown, for example, in other figures. It shows:

1 a circuit diagram of a circuit arrangement with a two-part DC-DC controller, a tripartite voltage intermediate circuit and a three-phase 4-point inverter;

2 a circuit diagram of a circuit arrangement according to an embodiment, in which a DC voltage source has a voltage center, and in which a middle capacitor of a voltage intermediate circuit is formed into two parts, wherein the middle potential point is grounded;

3 a circuit diagram of a circuit arrangement according to an embodiment, in which a two-part DC-DC controller in each of its two circuit parts comprises a plurality of parallel DC-DC controller;

4 a circuit diagram of a circuit arrangement according to an embodiment, in which several DC voltage sources are connected via parallel DC-DC controllers of a two-part DC-DC controller to a three-part voltage intermediate circuit;

5 in six diagrams, how individual switches of a 4-point inverter are controlled so that an AC voltage is generated as the sum of individual phase voltages by means of a carrier method;

6A a circuit diagram of a three-part voltage intermediate circuit with a 4-level diode-clamped inverter as an inverter;

6B a circuit diagram of a three-part voltage intermediate circuit with a first 4-level T-type inverter as an inverter;

6C a circuit diagram of a three-part voltage intermediate circuit with a second 4-level T-type inverter as an inverter;

7A a circuit diagram of a three-part voltage intermediate circuit with a 4-level multi-point clamped inverter as an inverter;

7B a circuit diagram of a three-part voltage intermediate circuit with a 4-level Active-Neutral-Point Clamped inverter as an inverter;

8A a circuit diagram of a circuit arrangement according to an embodiment with a 2 × 2-level inverters as inverters with separate windings;

8B a circuit diagram of a circuit arrangement according to an embodiment with a 2 × 3-level Wechselrichter as a inverter with separate windings;

9A a circuit diagram of a circuit arrangement according to an embodiment with a 2 × 2-level inverter as an inverter with inductive coupling between two half-bridges of the inverter and

9B a circuit diagram of a circuit arrangement according to an embodiment with a 2 × 3-level inverter as an inverter with inductive coupling between two half-bridges of the inverter.

1 shows a circuit diagram of a circuit arrangement 1 for the exchange of electrical energy between a DC voltage source and / or sink B on the one hand and an AC voltage sink and / or source on the other. The circuit arrangement 1 has a two-part DC-DC controller 10 on, which is connected to the plus and minus pole of the DC voltage source B. The two-part DC-DC controller 10 regulates the current flow from and to a tripartite voltage intermediate circuit 20 , The voltage intermediate circuit 20 is between the two-part DC-DC controller 10 and an inverter 30 interposed, which is designed as a three-phase 4-point inverter. The inverter 30 has three phase circuit parts 31 . 32 and 33 on, each having an output (and / or input), at which the circuit arrangement in each case a phase voltage U _{a '} , U _a'' and U _3''' provides. An alternating voltage U _a is composed of the three individual phase voltages U _{a '} , U _a'' and U _a''' which are connected to the three phase circuit parts 31 . 32 . 33 of the inverter 30 to be provided.

The embodiments illustrated in the figures are embodiments in which there is usually an energy transfer from a DC voltage source to an AC sink. Alternatively or additionally, the DC voltage source B could also be designed as a DC voltage sink, which is supplied by the circuit arrangement with a DC voltage which is fed by an AC voltage source with the AC voltage U _a . Only for the sake of clarity, the figures are only described so that a transfer of energy from the DC side takes place on the AC side. An energy transfer in the opposite direction is - even if not explicitly described - also possible and feasible.

The two-part DC-DC controller 10 has a first circuit part 11 and a second circuit part 12 on. The first circuit part 11 is connected to the negative pole of the DC voltage source B. The second circuit part 12 is connected to the positive pole of the DC voltage source B. The first circuit part 11 and the second circuit part 12 are each designed as a high-low setter. For this purpose, the first circuit part 11 a negative coil L _n on which the first circuit part 11 is connected to the negative pole of the DC voltage source B. The negative coil L _n acts as a storage choke, in short referred to as 'choke'. The first circuit part 11 also has an outer negative switch S _nl , and an inner negative switch S _nh . Depending on the switch position of the outer negative switch S _nl and the inner negative switch S _nh controls and / or controls the first circuit part 11 , with which potential point of the tripartite voltage intermediate circuit 20 the negative terminal of the DC voltage source B is how long is connected or is.

Analogously, the second circuit part 12 a positive coil L _p , which serves as a storage choke. About an inner plus switch S _pl and controls an external plus switch S _ph and / or controls the second circuit part 12 , with which potential point of the voltage intermediate circuit 20 the plus point of the DC voltage source B is connected. The two circuit parts 11 and 12 are designed as half bridges of the two-part DC-DC controller.

The three-part voltage intermediate circuit 20 has three series-connected capacitors, namely a plus capacitor C _p , a center capacitor C ₀ and a negative capacitor C _n . In each case, the positive voltage U _Cp , the center voltage U _C0 and the negative voltage U _{Cn are applied} to these three capacitors, as in FIG 1 shown.

Due to the three capacitors connected in series, the three-part voltage intermediate circuit provides 20 four different potential points provided: On the plus side of the positive capacitor C _p to a positive potential point PP, on the opposite side of the positive capacitor C _p the plus mid-potential point PP0 which rests simultaneously on the positive side of the center capacitor C _0th On the other side of the center capacitor C ₀ , namely between the center capacitor C ₀ and the negative capacitor C _n , the minus center potential point PN0 is arranged. On the other side of the capacitor C _n , ie at the level of the lowest electrical potential, a negative potential point PN is arranged.

The first circuit part 11 of the DC-DC controller 10 controls and / or regulates whether the negative terminal of the voltage source B is connected via the inductor L _n to the negative potential point PN or the minus center potential point PN0. The second circuit part 12 of the two-part DC-DC controller 10 controls and / or regulates whether the positive pole of the DC voltage source B via the storage inductor L _{p is} connected to the positive potential point PP or the plus-mid potential point PP0.

The inverter 30 points in each phase circuit part 31 . 32 and 33 a positive switch S _pi , a middle positive switch S _p0i , a center negative switch S _n0i and a negative _switch S _ni , wherein the letter i stands for the respective phase with i = 1, 2 or 3. The inverter controls and / or regulates these four switches 30 for each phase circuit part, which potential point of the intermediate circuit 20 at one of the output potentials of the phase voltages U _{a '} , U _a'' and U _a''' is present. From these three phase voltages U _{a '} , U _a'' and U _a''' , the output AC voltage U _{a is} composed.

The two-part DC-DC controller 10 may for example consist of two identical high-low setters whose half-bridges consist of the switches S _ph and S _pl and S _nh and S _nl , and which are connected to the positive capacitor C _p and the negative capacitor C _n . The switches of the DC-DC controller 10 and / or the switches of the inverter 30 can be designed as a power electronic semiconductor switch, such as a MOSFET (metal oxide semiconductor field-effect transistor) or as an IGBT (insulated-gate bipolar transistor) with or without antiparallel connected diode. About the inductors L _p and L _n , the DC voltage source B is connected to the voltage U _B to the circuit arrangement. In the event that the voltage source B no further connection, for example, as an average potential (see below 2 ) to a particular ground or reference potential, one of the two inductors L _p or L _n may be omitted.

The one for the circuit arrangement 1 permissible, variable voltage range of U _B goes from the center voltage U _C0 to the sum of the three partial voltages U _Cp + U _C0 + U _C0 . Thus, the DC voltage U _B satisfies the equation U _C0 ≦ U _B ≦ U _Cp + U _C0 + U _Cn . If the ratio of the center voltage U _C0 to the outer voltages U _Cp chosen to be equal to U _Cn for reasons of symmetry is usually, but not necessarily substantially equal, the voltage range is sufficiently high for typical applications, for example in applications in which batteries, solar cells, Capacitors, fuel cells, etc. are used as DC voltage source with variable voltage level.

By this arrangement of the circuit arrangement 1 For example, the blocking voltage of the semiconductor components in the two-part DC-DC controller (such as the four switches _S.sub.ph , _S.sub.pl , _S.sub.nh and _S.sub.nl ) can be chosen to be significantly smaller than in conventional circuits with high-buck converters. This reduces the component costs for the power semiconductors. Furthermore, power semiconductors which are designed for smaller blocking voltages have a reduced ohmic resistance in the switched-on state. As a result, the losses occurring in the semiconductors can be reduced by using only commercially available standard components by this circuit topology alone.

Furthermore, power semiconductors with low blocking voltage are able to operate at higher switching frequencies, which basically reduces the construction costs of the inductors L _p and L _{n and} reduces losses due to harmonics in the current. Since the voltage time surface occurring across these two reactors is due to the connection of the split DC-DC controller 10 at the two partial voltages U _Cp and U _Cn significantly smaller than conventional Hoch-Tiefsetzstellern fails, the construction cost of these chokes is greatly reduced. Thus, overall, the construction cost of the chokes and the efficiency of the DC-DC actuator decreases 10 increases.

2 shows a circuit diagram of an embodiment of a circuit arrangement 1' for a voltage source having a center terminal which is electrically grounded, for example. The circuit arrangement 1' has a voltage intermediate circuit 20 in which the center capacitor consists of two series-connected single capacitors, namely the center minus capacitor C _0n and the center plus capacitor C _0p . The middle potential of the DC voltage source is as well as the average potential point of the voltage intermediate circuit 20 ' on electrical ground.

3 shows a circuit arrangement 1'' with which both the operating characteristics and the power electronic complexity of the circuit arrangement has been further improved by parallelizing several DC-DC actuators. The two-part DC-DC controller 10 ' has a first circuit part 11 ' and a second circuit part 12 ' on. It could also be provided more than two parallel DC-DC controller in each case. Both circuit parts, so both half-bridges, each have two parallel DC-DC controller, which is an application of the circuit arrangement 1'' allows for an energy exchange in both directions, ie from the DC side to the AC side and vice versa.

By staggered clocking of the individual half-bridges in the two-part DC-DC controller 10 ' The construction cost of both the inductors L _p1 , L _p2 , L _n1 and L _n2 and the capacitors is lowered due to a lower AC load. In the partial load range, switching off individual half-bridges can lead to advantages in efficiency. Assign the two circuit parts designed as half bridges 11 ' and 12 ' in each case two active semiconductor switches, namely the switches S _{p / nhx} and S _p'nlx (with x = 1, 2, ... as the number of the phase of the DC-DC-controller), can in both directions electrical energy between the DC voltage source and the voltage intermediate circuit 20 be replaced. Should the circuit arrangement 1'' be used only for an application that requires only the energy exchange in one direction, so each one active switch can be replaced by a respective diode.

Thus, for the energy flow from the DC voltage source towards the voltage source 20 for the _boost converter operation, the switches S _phx and S _{nlx are} replaced by diodes. This application is useful, for example, in the use of solar cells as a DC voltage source or DC voltage sources, as the effort to control the active switch is reduced. If an application with an energy flow is provided only in the direction of the DC voltage source B, ie from the voltage intermediate circuit 20 out, so the switch S _plx and S _nhx can be replaced by diodes for operation as a _buck converter.

4 shows an embodiment of the circuit arrangement as a circuit arrangement 1''' in which a plurality of, for example, mutually different DC voltage sources to the circuit arrangement 1''' are connected. In the circuit diagram, the in 4 are shown, these are shown by way of example as DC voltage source B1 and DC voltage source B2. However, embodiments can also be implemented analogously in which more than two DC voltage sources are connected to the circuit arrangement 1''' are shot or connected.

This is indicated by the two-part DC-DC controller 10 '' for each voltage source, a DC-DC converter in its first circuit part 11 ' and in its second circuit part 12 ' on. The DC voltage sources B1, B2, etc. can be formed independently of each other and thus provide different DC voltages and have different variations in the voltage level. The circuit arrangement 1''' allows for each DC voltage source connected an individual voltage adjustment, which allows, for example in the field of photovoltaic maximum tower point tracking (MPP tracking) for each connected via the respective DC-DC controller module string. Such a module string may comprise a plurality of solar modules, which may each be connected as a string such as one of the DC voltage sources B1 and B2, etc.

If the DC voltage sources are designed as batteries, the circuit arrangement allows 1''' the connection of several battery stacks, where each battery stack can be charged or discharged independently of each other with different currents at different voltages depending on the respective state of charge. To the circuit arrangement 1''' Also, a combination of different DC power sources can be connected, such as a combination of batteries and fuel cells, batteries and (super) capacitor storage, photovoltaic and battery, etc. The circuitry 1''' is flexible in terms of connecting different DC sources and / or sinks.

Each individual DC-DC controller as a subcomponent of the two-part DC-DC controller 10 ' can be designed for the respective DC voltage source as a multi-phase, parallel switched high-Tiefsetzschalter, analogous to the DC-DC-controllers in the circuit parts 11 ' and 12 ' in 3 , All individual DC-DC controllers may be formed of modules with the same components, ie with the same transistors, diodes, chokes and / or Capacitors. These modules can be interconnected for flexible use according to the requirements of the respective DC voltage source, that is, depending on their number, their current strength, their energy output, etc. Each DC voltage source can via one or more DC-DC controller of the two-part DC-DC controller 10 ' to the voltage intermediate circuit 20 be connected. Thus, the circuit arrangement 1''' modular design and thus enables a high scalability for the construction of the entire system, as well as a simple production and installation.

The inverter 30 , which is designed for four potential points, so for example as a 4-point inverter or 4-level inverter is shown in the figures in a functional diagram with switches. The inverter 30 generated from the DC voltage U _B or the partial voltages of the voltage intermediate circuit 20 an AC voltage U _a . The fundamental amplitude of the AC voltage U _a and their frequency are on the inverter 30 freely adjustable.

For this purpose, up to four discrete voltage stages are used, namely the four potential points PP, PP0, PN0 and PN of the voltage intermediate circuit 20 ,

5 shows in a total of six diagrams, as by the switch positions of the inverter 30 , more precisely, the switch positions of the phase circuit parts 31 . 32 respectively. 33 , an AC voltage U _{a is} generated. The uppermost diagram shows a nominal value of a nominal AC voltage U _{a *} which is present at the output of the inverter 30 should be tapped or provided.

In 5 is shown in the second diagram from above the actually provided voltage waveform of the output voltage U _a , which is due to switch positions in the inverter 30 yields and is provided as a phase voltage.

• – +U_Cp + U_C0/2, wenn Schalter S_py aktiv ist,
• – +U_C0/2, wenn Schalter S_p0y aktiv ist,
• – U_C0/2, wenn Schalter S_n0y aktiv ist und
• – –U_Cn – U_C0/2, wenn Schalter S_ny aktiv ist.

In each of the four potential points PP, PP0, PN0 and PN, the following four voltage levels are provided:

• - + U _Cp + U _C0 / 2, when switch S _{py is} active,
• - + U _C0 / 2, if switch S _{p0y is} active,
• - U _C0 / 2, if switch S _{n0y is} active and
• - U _Cn - U _C0 / 2, if switch S _{ny is} active.

Where y is the number of the respective phase circuit part in which the switch is arranged, see also 1 , The inverter 30 controls and / or regulates the individual switches so that in each phase circuit part 31 . 32 and 33 in each case only one of the four switches mentioned is active, ie only one of the four potential points of the voltage intermediate circuit 20 with an output of the inverter 30 connected is.

The associated switching signals of the individual switches of the inverter 30 can be produced by a suitable carrier method. The switching signals for the four switches of a phase are in the lower four diagrams of the 5 shown. The voltage curve of the output AC voltage U _a arises with four levels ('Levels') for one phase. In this case, the harmonic content of the AC voltage U _{a is} significantly reduced compared to 2-point or 3-point converters.

During operation, the partial voltages at the voltage intermediate circuit 20 be dynamically adjusted according to the requirements of the AC voltage amplitude. Thus, by the circuit arrangement, a reduction of the switching losses in the semiconductor components by a targeted lowering of the partial voltages in the voltage intermediate circuit 20 allows. Alternatively, a higher voltage can be generated in the voltage intermediate circuit than is provided by the DC voltage U _B , when the load on the inverter side requires a higher voltage. This can be the case, for example, with battery-powered drives.

This optimization systematically reduces the harmonic content in the AC voltage U _a . The switching states of the semiconductor switches are chosen so that on the one hand, the desired fundamental oscillation of the AC voltage U _{a is} generated, and on the other hand, the load of the capacitors in the voltage intermediate circuit 20 for example symmetrically. In this case, currents are preferably in the capacitors of the voltage intermediate circuit 20 set to be averaging either over the time range of a clock period or over the time range of a period of the fundamental of the AC voltage U _a , which can be ensured by a suitable control of the semiconductor switch. This can be realized by redundant switching states, which are active according to the requirements for certain periods of time. The associated switching patterns can be optimized so that the most efficient operation of both the inverter 30 as well as the two-part DC-DC controller 10 is possible. In this case, the ratio of the internal voltage, that is, the center voltage U _C0 , to the two external voltages U _Cp and U _{Cn can} be advantageously used as the degree of freedom for the optimization. The optimization of the switching patterns and the choice of partial voltages in the voltage intermediate circuit 20 can be adjusted so that the harmonic content is selectively reduced in the AC voltage U _a and / or certain harmonics are minimized.

Embodiments of the inverter

For picking up the four potential points of the voltage intermediate circuit 20 over the inverter coupled to the four potential points 30 For example, various embodiments of an inverter may be used.

6A shows a tripartite voltage intermediate circuit 20 , at whose potential points an inverter 30 ' is connected, which is designed as a 4-level diode-clamped inverter. This is known with a corresponding control method, for example, from the article "A new link potential control scheme for four-level inverters with passive rectifier" by Rae-Young Kim and Yo-Han Lee and Dong-Seok Hyun. The control methods presented in this article can in principle be transferred to other 4-point inverters. An advantage of the inverter 30 ' is a low voltage load of the semiconductor in the blocking mode. Thus, the three semiconductor switches in the upper and lower branch only have to withstand blocking voltages with at least the respective capacitor voltage U _{Cp / 0 / n} . The so-called clamp diodes, which represent the connection to the two intermediate potentials of the intermediate circuit, should have a minimum blocking voltage of U _Cp or U _Cn (at the upper and lower diodes) and U _Cp + U _C0 or U _Cn + U _C0 (at the middle two diodes). The higher blocking voltage of the middle diodes can be realized by the series connection of two or more diodes. The inverter 30 ' can be made up of standard half-bridge modules with the additional clamp diodes. The clamp diodes can be replaced by actively switched transistors.

6B and 6C show inverter in a circuit diagram 30 '' and 30 ''' , which are designed as a 4-level T-type inverter, which are known as so-called "nested multilevel configuration" from the same article by dos Santos Junior, EC and Muniz, JHG and da Silva, ERC and Jacobina, CW.

Compared to 4-level diode-clamped inverters, the four clamp diodes per phase are eliminated. The inverters 30 '' and 30 ''' have an upper and a lower semiconductor switch whose blocking voltages for the sum of the capacitor voltages (U _Cp + U _C0 + U _Cn ) in the voltage _{intermediate circuit} 20 are designed. The two middle switches, which connect to the intermediate potentials of the voltage intermediate circuit 20 are performed by power electronic components so that they are able to block and conduct in both directions. This can be done, for example, with the in 6B and 6C embodiment shown by the series connection of two oppositely arranged standard semiconductor switches with integrated anti-parallel diode can be realized. In an alternative use of special reverse blocking transistors can be dispensed with each of the two diodes. Thus, the two transistors are connected in parallel in the opposite forward direction. The associated semiconductors should have at least one blocking voltage of U _Cp + U _C0 or U _Cn + U _C0 .

7A shows a circuit diagram of an inverter 30A ' , which is designed as a 4-level multi-point clamped inverter, for example, from the article "Multilevel Converters for UPS applications: Comparison and Implementation" by Lega, A. and Munk-Nielson, S. and Blaabjerg, F. and Casadei, D. is known. The inverter circuit 30A ' has for the positive capacitor C _p and the negative capacitor C _n each have a half-bridge, which has two power semiconductor switch. The blocking voltage of the components involved should be at least U _Cp or U _Cn . To the two centers of the two half-bridges, a further half-bridge is connected, the center of which provides the connection point of the output voltage U _a . The blocking voltages of these semiconductor components should be at least U _Cp + U _C0 or U _Cn + U _C0 . An advantage of this circuit is that the inverter 30A ' can be built from conventional half-bridges and no additional semiconductor switches such as diodes needed.

7B shows a circuit diagram of another embodiment of an inverter 30A '' as a 4-level Active-Neutral-Point-Clamped Inverter. Such an inverter is known, for example, from the article "A new four-level PWM inverter topology for high power applications" by Perantzakis, GS and Xepapas, FH and Manias, SN. The inverter 30A '' has a 3-level neutral-point-clamped (NPC) inverter with active switches in parallel to the two clamp diodes, whose center tap is connected via a half-bridge to the two intermediate potentials of the DC link. This additional half-bridge should have components with a minimum blocking voltage of U _C0 . The semiconductor components of the NPC should be designed for the voltages U _Cp + U _C0 and U _Cn + U _C0 . The inverter 30A '' has conventional half bridges without requiring additional components. The inverter 30A '' allows optimization of the conduction and switching losses in the semiconductor devices by redundant switching states, without negatively affecting the harmonics in the AC voltage.

8A shows an inverter 30B ' which is formed as a 2 × 2-point inverter. The inverter offers the power supply for individual, separate windings, as are components of transformers and electrical machines, for example 30B ' Benefits in terms of construction costs. Each individual phase of the 2 × 2-point inverter has two half-bridges which feed the two terminals of a winding of the electric machine. The half-bridge which is connected to the center capacitor C ₀ can be designed with a reduced blocking voltage corresponding to U _C0 . The half-bridge is used by high-frequency switching advantageous for pulse width modulation (PWM) of the proportionate voltage. The second half-bridge is connected to the outer terminals of the intermediate circuit and should therefore be designed with a blocking voltage of at least U _Cp + U _C0 + U _Cn . The second half-bridge is used for low-frequency switching for the external voltage levels of the voltage intermediate circuit 20 , By the circuit arrangement with the inverter 30B ' For example, one winding of the machine or transformer can be supplied with the following four voltage levels for U _a : + U _C0 + U _Cn , U _Cn , -U _Cp , and -U _C0 - U _Cp .

The center capacitor C ₀ may be as in 2 be divided into two parts, with one or both half-bridges of the inverter is replaced by a 3-point inverter. This is in a schematic in 8B shown. The middle connection of the 3-point inverter is connected to the middle potential. As a result, the possible number of steps in the voltage curve is increased, whereby the voltage quality is further increased. The 3-point inverter can be realized either as T-type or NPC 3-point inverter. In principle, for connection to a transformer or to a machine, the circuit arrangement may comprise a combination of two 2-point inverters, two 3-point inverters or one 2-point and one 3-point inverter.

9A and 9B show circuit diagrams of another embodiment of the inverter as an inverter 30C ' respectively. 30C '' , In this case, the two half-bridges of a phase of the respective inverter are connected by means of two reactors or a magnetically coupled throttle. This allows the inverter 30C ' respectively. 30C '' Generate any number of phases for an AC voltage system and / or a three-phase voltage system. The characteristics of the inverters 30C ' and 30C '' are comparable to the properties of the in the 8A and 8B shown inverter 30B ' and 30B '' , As in these embodiments, also in the inverters 30C ' and 30C '' one or both half-bridges are replaced by 3-point converters in all combinations.

LIST OF REFERENCE NUMBERS

1

circuitry

1

circuitry

1''

circuitry

1'''

circuitry

10

two-part DC-DC controller

10 '

two-part DC-DC controller

11

first circuit part of the two-part DC-DC controller

11 '

first circuit part of the two-part DC-DC controller

12

second circuit part of the two-part DC-DC controller

12 '

second circuit part of the two-part DC-DC controller

20

Voltage link

20 '

Voltage intermediate circuit with center potential

30

inverter

30 '

4-level diode-clamped inverter

30 ''

4-level T-type inverter

30 '' '

4-level T-type inverter

30A '

4-level multi-point clamped inverter

30A ''

4-level Active-Neutral-Point-Clamped inverter

30B '

2 × 2-point inverter

30B ''

2 × 3-point inverter

30C '

2 × 2-point inverter

300 ''

2 × 3-point inverter

31

Phase switching part for the first phase

32

Phase switching part for the second phase

33

Phase circuit part for the third phase

B

DC voltage source

B1

first DC voltage source

B2

second DC voltage source

C _n

minus capacitor

C ₀

mid capacitor

C _0n

Middle-minus capacitor

C _0p

Middle-Plus capacitor

C _n

plus capacitor

L _n

minus coil

L _p

plus coil

PP

Plus potential point

PP0

Plus mid potential point

PN0

Minus-center potential point

PN

Minus potential point

S _nh

internal minus switch

S _nl

external minus switch

_Ph

outer plus switch

S _pl

internal minus switch

S _n1

Negative switch of the first phase

S _n2

Negative switch of the second phase

S _n3

Negative switch of the third phase

S _n01

Center-negative switch of the first phase

S _n02

Center-negative switch of the second phase

S _n03

Center-negative switch of the third phase

S _p1

Positive switch of the first phase

S _p2

Positive switch of the second phase

_P3

Positive switch of the third phase

S _p01

Center-positive switch of the first phase

S _p02

Center-positive switch of the second phase

S _p03

Center-positive switch of the third phase

U _Cn

minus voltage

U _C0

center voltage

U _C0n

Middle-minus voltage

U _C0p

Middle-Plus voltage

U _Cp

plus voltage

U _a

AC

U _{a '}

Phase voltage of the first phase

U _{a ''}

Phase voltage of the second phase

U _{a '''}

Phase voltage of the third phase

U _{a *}

Should ac

U _B

DC

U _{B / 2}

Half DC

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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 102009047936 A1 [0004]

Claims (15)

Circuit arrangement for exchanging electrical energy between at least one DC voltage source (B) and / or sink on the one hand and at least one AC voltage sink and / or source on the other hand, with - a two-part DC-DC converter ( 10 ; 10 ' ) for connecting the circuit arrangement ( 1 ; 1'; 1''; 1''' ) to the plus and minus pole of the DC voltage source (B) and / or sink, - an inverter ( 30 ; 30 '; 30 ''; 30 '''; 30A '; 30A '; 30B '; 30B ''; 30C '; 30C '' ) for at least four potential points with at least one phase ( 31 . 32 . 33 ) for connecting the circuit arrangement ( 1 ; 1'; 1''; 1''' ) to the AC voltage sink and / or source and - an at least three-part voltage intermediate circuit ( 20 ; 20 ' ) between the two-part DC-DC controller ( 10 ; 10 ' ) and the inverter ( 30 ; 30 '; 30 ''; 30 '''; 30A '; 30A ''; 30B '; 30B ''; 30C '; 30C '' ) is switched. Circuit arrangement according to Claim 1, in which the two-part DC-DC controller ( 10 ; 10 ' ) the exchange of electrical energy between the DC voltage source (B) and / or sink and the three-part voltage intermediate circuit ( 20 ; 20 ' ) controls and / or regulates. Circuit arrangement according to Claim 1 or 2, a first circuit part ( 11 ; 11 ' ) of the two-part DC-DC controller ( 10 ; 10 ' ) is electrically connected to the negative pole of the DC voltage source (B) and / or sink, and a second circuit part ( 12 ; 12 ' ) of the two-part DC-DC controller ( 10 ; 10 ' ) is electrically connected to the positive pole of the DC voltage source (B) and / or sink. Circuit arrangement according to one of the preceding claims, wherein a first circuit part ( 11 ; 11 ' ) and a second circuit part ( 12 ; 12 ' ) of the two-part DC-DC controller ( 10 ; 10 ' ) each having a boost converter, a buck converter or a boost / buck converter. Circuit arrangement according to claim 4, wherein the first circuit part ( 11 ; 11 ' ) and the second circuit part ( 12 ; 12 ' ) of the two-part DC-DC controller ( 10 ; 10 ' ) are symmetrical to each other and have the same, corresponding to each other circuit elements. Circuit arrangement according to one of the preceding claims, wherein the three-part voltage intermediate circuit ( 20 ; 20 ' ) - at least three series-connected capacitors (C _p , C ₀ , C _n ) and - in each case between the series-connected capacitors (C _p , C ₀ , C _n ) and at the two outer ends of the at least three connected in series Capacitors (C _p , C ₀ , C _n ) electrical potential points (PP, PP0, PN0, PN) for contacting both by the two-part DC-DC controller ( 10 ; 10 ' ) as well as through the inverter ( 30 ; 30 '; 30 ''; 30 '''; 30A '; 30A ''; 30B '; 30B ''; 30C '; 30C '' ) having. Circuit arrangement according to Claim 6, in which - a minus capacitor (C _n ) of the three-part voltage intermediate circuit ( 20 ; 20 ' ) via a first circuit part ( 11 ; 11 ' ) of the two-part DC-DC controller ( 10 ; 10 ' ) is assigned to the negative pole of the DC voltage source (B) and / or sink, - a positive capacitor (C _p ) of the three-part voltage intermediate circuit ( 20 ; 20 ' ) via a second circuit part ( 12 ; 12 ' ) of the two-part DC-DC controller ( 10 ; 10 ' ) is associated with the positive pole of the DC voltage source (B) and / or sink, and - a middle _capacitor (C ₀ ; C _0p , C _0n ) is connected in series between the negative capacitor (C _n ) and the positive capacitor (C _p ). Circuit arrangement according to claim 7, wherein the DC voltage source (B) and / or sink has a center potential and the center _capacitor (C _0p , C _0n ) is formed in two _parts , wherein the center potential of the DC voltage source (B) and / or sink electrically between the two-part _{Middle capacitor} (C _0p , C _0n ) is switched. Circuit arrangement according to one of claims 6 to 8, wherein the inverter ( 30 ; 30 '; 30 ''; 30 '''; 30A '; 30A ''; 30B '; 30B ''; 30C '; 30C '' ) is designed and provided, the electrical potential at each one of the four potential points (PP, PP0, PN0, PN) of the tripartite voltage intermediate circuit ( 20 ; 20 ' ) to and / or from a phase voltage (U _{a '} , U _a'' , U _a''' ) of the AC voltage (U _a ) of the AC voltage sink and / or source to modulate. Circuit arrangement according to one of the preceding claims, wherein the inverter ( 30 ; 30 '; 30 ''; 30 '''; 30A '; 30A ''; 30B '; 30B ''; 30C '; 30C '' ) an electrical contact between potential points (PP, PP0, PN0, PN) of the three-part voltage intermediate circuit ( 20 ; 20 ' ) and the AC voltage sink and / or source controls and / or regulates. Circuit arrangement according to one of the preceding claims, wherein the inverter ( 30 ; 30 '; 30 ''; 30 '''; 30A '; 30A ''; 30B '; 30B ''; 30C '; 30C '' ) electrical potential points (PP, PP0, PN0, PN) of the three-part voltage intermediate circuit ( 20 ; 20 ' ) modulated by means of a pulse width modulation to an output AC voltage (U _a ) for the AC voltage sink, and / or wherein the inverter ( 30 ; 30 '; 30 ''; 30 '''; 30A '; 30A ''; 30B '; 30B ''; 30C '; 30C '' ) sets an AC input voltage (U _a ) of the AC voltage source as a PWM signal to electrical potential points (PP, PP0, PN0, PN) of the three-part voltage intermediate circuit. Circuit arrangement according to one of the preceding claims, wherein the inverter ( 30 ; 30 '; 30 ''; 30 '''; 30A '; 30A ''; 30B '; 30B ''; 30C '; 30C '' ) two-phase with two phase circuit parts ( 31 . 32 . 33 ) is formed and an alternating voltage (U _a ) as the sum of two phase voltages (U _{a '} , U _a'' , U _a''' ) at the two phase circuit parts ( 31 . 32 . 33 ) modulated and / or demodulated. Circuit arrangement according to one of claims 1 to 11, wherein the inverter ( 30 ; 30 '; 30 ''; 30 '''; 30A '; 30A ''; 30B '; 30B ''; 30C '; 30C '' ) three-phase with three phase circuit parts ( 31 . 32 . 33 ) is formed and an alternating voltage (U _a ) as the sum of three phase voltages (U _{a '} , U _a'' , U _a''' ) at the three phase circuit parts ( 31 . 32 . 33 ) modulated and / or demodulated. Circuit arrangement according to one of the preceding claims, wherein the inverter is designed as a 4-point inverter ( 30 ; 30 '; 30 ''; 30 '''; 30A '; 30A '' ), as a 2 × 2-point inverter ( 30B '; 30C ' ), as a 2 × 3-point inverter ( 30B ''; 30C '' ) or a combination of a 1 × 2-point inverter and a 1 × 3-point inverter. Method for exchanging electrical energy between at least one DC voltage source (B) and / or sink on the one hand and at least one AC voltage sink and / or source on the other hand, wherein - a two-part DC-DC converter ( 10 ; 10 ' ) the electrical connections between the plus and minus poles of the DC voltage source (B) and / or sink on the one hand and electrical potential points (PP, P0, PN0, PN) of a three-part voltage intermediate circuit ( 20 ; 20 ' ) controls and / or regulates - an inverter ( 30 ; 30 '; 30 ''; 30 '''; 30A '; 30A ''; 30B '; 30B ''; 30C '; 30C '' ) the electrical connections between the AC voltage sink and / or source and four different electrical potential points (PP, PP0, PN0; PN) of the three-part voltage intermediate circuit ( 20 ; 20 ' ) controls and / or regulates.

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