DE102017115646A1 - Circuit arrangement and method for exchanging electrical energy via an electrical machine - Google Patents

Abstract

Circuit arrangement for the operation of an electrical machine with at least 3 phases, which comprises connections for a power supply; a DC controller, which is connected on the input side to a terminal of the power supply and the output side bridges a first capacitor of a two-part DC link; the two-part intermediate circuit consisting of the first and a second capacitor, which are connected in series such that an intermediate potential is formed between the two capacitors, at the other end of the first capacitor, an upper potential is formed and at the other end of the second capacitor a lower potential is formed; the second terminal for the power supply connected to the lower potential; for each phase of the electric machine, a first half-bridge whose outer terminals are respectively connected to the upper and the lower potential and a second half-bridge whose outer terminals are respectively connected to the lower potential and the middle potential, while the center taps of the two half-bridges to Connecting the inductive load of the respective phase of the electrical machine serve.

Description

The invention relates to a circuit arrangement and method for exchanging electrical energy via an electrical machine.

In electric drive technology power electronics are used for drive control. These power electronics work z. B. with a DC link. The input voltage of the voltage source is thereby converted suitable for the electrical machine into an electrical variable, so that a rotating field is formed. This conversion is done by frequent switching by means of circuit breakers or power semiconductors in a bridge circuit. By switching the current commutes in his direction and there is an AC or three-phase current suitable for the machine.

In a 3-phase motor and a full bridge circuit, there are two so-called B6 bridges, which are normally synchronized to operate e.g. B. adjust the current and direction through a coil.

The circuit breakers of the bridge circuit may be implemented by semiconductor devices such as MOSFETs or IGBTs. The timing of the control of the switch can, for. B. be determined by the programming of a microcontroller.

Regardless of the operation of an electric motor circuits are known from the prior art, which have in common that they achieve a reduction of the associated throttle by a special embodiment of a bridge circuit upstream DC adjuster. These exist in various embodiments.

M. Gommeringer, F. Kammerer, J. Kolb, M. Braun, "Novel DC-AC Converter Topology for Multilevel Battery Energy Storage Systems", PCIM Europe 2013, Nuremberg, 14.-16. May 2013 teaches a cell or cascade connection of several cells of a multilevel converter or medium-voltage converter. In this case, a single-phase load or a network is fed on the output side. In the case of a desired higher voltage, several multilevel power converters are connected in series. This is necessary because components have limited reverse voltages. Nevertheless, an increased voltage up to several 100 kV can be generated by series connection. There must be no central battery, but the power supply must be done cell by cell.

The circuit arrangement is intended for the operation of a serial multilevel topology. For this purpose, a full bridge must be used on the output side, which in this case is asymmetrical. A three-phase load can only be operated if several modules are interconnected and have different power supplies. In this case, all voltage sources used should have the same characteristics, ie, for example, the same battery cells. An exchange of energy between the individual sources is then no longer possible without further ado. Operation of sources with different characteristics (battery, fuel cell, etc.) is also not readily possible.

A circuit analysis carried out with this structure and the control method derived therefrom show that it is not possible to individually regulate both voltages of both capacitors of the DC link, but at any time to set a stable operating point.

J. Kolb, M. Gommeringer, Karlsruhe Institute of Technology, "Circuitry and methods for the exchange of electrical energy" . DE 10 2014 005 124 A1 , 08.10.2015 teaches a drive converter. The proposed circuit is based on the first-mentioned prior art and already has three-phase bridges for the operation of three-phase machines. By replicating an assembly several voltage sources of different characteristics can be operated. However, it can only exchange operating point-dependent electrical energy between different sources, as to control all capacitor voltages an active power demand from the machine is needed.

M. Gommeringer, A. Schmitt, J. Kolb, Karlsruhe Institute of Technology, "Circuitry and methods for tapping electrical power from multiple module strings" . DE 10 2014 002 592 A1 , 27.08.2015, teaches a solar inverter. The circuit is used as an MPP tracker for a solar inverter and can naturally operate as a pure DC / DC converter no three-phase machine and no power between the sources (here: photovoltaic modules) exchange.

A disadvantage is that an operation of an electric machine with multiple phases in efficient and flexible use of one or more power supplies is not possible. The prior art is constructed only single phase and thus not suitable.

Also, only an output-side supply of energy is possible, but not a return to the source, as possible with an electric machine in generator mode.

The object of the invention is therefore to provide a circuit arrangement and method with which an electrical machine with at least 3 phases can be operated such that only one power supply is necessary or alternatively multiple voltage sources can be operated flexibly, with optional energy also being able to be fed back , At the same time, a reduction of the component costs for the DC adjuster can be achieved.

The object of the invention is achieved by a circuit arrangement for the operation of an electrical machine or a transformer arrangement with at least 3 phases. This includes connections for a power supply. Furthermore, a DC controller, which is connected on the input side to a terminal of the power supply and the output side bridges a first capacitor of a two-part DC link. Furthermore, the two-part intermediate circuit consisting of the first and a second capacitor, which are connected in series such that between the two capacitors, an average potential is formed at the other end of the first capacitor, an upper potential is formed and at the other end of the second Capacitor is designed a lower potential. Furthermore, the second connection for the power supply, which is connected to the lower potential. Furthermore, for each phase of the electrical machine or transformer arrangement, a first half-bridge, the outer terminals of which are respectively connected to the upper and the lower potential, and a second half-bridge, the outer terminals of which are respectively connected to the lower potential and the middle potential. The center taps of the two half bridges serve to connect the inductive load of the respective phase of the electrical machine or transformer arrangement.

Potential here means electrical potential. Connected referred to electrically connected here. This may be a direct connection, d. H. one in which the current path is unaffected or uninterrupted. However, it will be apparent to those skilled in the art that compounds having circuit components which affect the connection and which do not materially affect the basic principle of this circuit are also included.

By means of the invention, it is advantageously possible to reduce the complexity of the component (that is to say mass / volume, costs), for example. B. for a drive converter in the automobile, drive a three-phase machine and exchange energy between different power supplies, especially DC sources.

With regard to the control of the power semiconductors, there are advantages over many prior art, since a total of fewer transistors must be supplied with corresponding gate driver circuits and the control-related outlay (modulation, voltage detection) becomes lower.

The invention is suitable for machines whose winding terminals are all led to the outside. However, it is applicable to synchronous or asynchronous machines.

In a particular embodiment of the circuit arrangement, the DC controller comprises a throttle, which is connected on the one hand to the one terminal of the power supply and on the other hand to the center tap of a half-bridge of the DC adjuster. Also included is the half-bridge of the DC regulator whose outer terminals bridge the first capacitor, d. H. associated with the upper and middle potential.

The DC controller must at least be designed so that the different voltage variances of the voltage source, the z. B. depending on the state of charge or the output characteristic of the voltage source can be processed without damage in the context of the desired electrical properties.

Bridge circuits are normally always connected with the same voltage. Advantageously, this does not have to be this way because the DC controller allows flexible control.

Advantageously, the input-side DC controller allows the reduction of the associated throttle and the transistors.

In a particular embodiment of the circuit arrangement, the circuit arrangement further comprises one or more further DC controllers, which are connected in parallel with the (first) DC controller.

Such arrays of actuators connected in parallel are also referred to as multiphase actuators. However, these stages have nothing to do with the phases of the electrical machine.

Advantageously, it is possible to reduce the construction costs for the throttles. Although two throttles are required for a two-phase controller, due to physical constraints, only one-quarter of the costs for a single reactor are incurred. Due to their volume and the material they are made of, the cost impact is here higher than the switching element (eg MOSFET) and the diode.

In a particular embodiment of the circuit arrangement, the circuit arrangement further comprises one or more further DC controllers, which are connected on the input side to a further connection for a further power supply and are connected on the output side parallel to the DC controller.

It may be desirable to provide the system with multiple power supplies (voltage sources). For example, in a fuel cell vehicle, two power sources, the fuel cell and the battery, exist. So far, it has been customary for each voltage source to use a separate DC / DC converter, via which the energy is fed into the vehicle electrical system.

Advantageously, there must be no intermediate step via the electrical system, since power supplies can be connected directly to the system. For this purpose, the DC controllers are controlled so that it is possible to determine from which source how much power / energy is called up. This also enables a comfortable energy management of the power supplies.

Of course, the previously explained purely parallel arrangement of several DC controllers (multiphase controller) can additionally be arranged for each of the different power supplies.

In a particular embodiment of the circuit arrangement, the DC controller bridges the output side instead of the first capacitor, the second capacitor. Furthermore, the second terminal for the power supply is connected to the upper potential instead of the lower one. Furthermore, the second half-bridge of each phase is connected to the upper potential instead of the lower potential.

In this modified circuit design, the DC controller finds place on the so-called negative side. Basically, this alternative topology is equal to the former, there is no functional difference and no advantage / disadvantage. While you want to keep the voltage at the second capacitor as low as possible in the variant of the negative side, this is the voltage at the first capacitor in the former positive variant. The second half bridge should always bridge the other capacitor of the DC link, like the DC adjuster.

In a particular embodiment of the circuit arrangement, one or more further DC controllers bridge one of the two capacitors of the intermediate circuit, the second half-bridge the other of the two capacitors of the intermediate circuit and the first half-bridge the series connection of both capacitors.

In a particular embodiment of the circuit arrangement, the electric machine has more than 3 phases.

Advantageously, the invention can also be applied to electrical machines or transformer arrangements having more than three phases.

Furthermore, instead of a machine and a transformer arrangement can be connected.

As a transformer arrangement, both a three-phase (or possibly multi-phase) transformer with 6 terminals on the primary side (comparable to the connection of a three-phase machine) as well as three (or more) individual single-phase transformers could be connected.

An application could be z. B. in power engineering with stationary storage.

The transferability of the invention from an electrical machine to a transformer would refer to one side of the transformer (eg, primary side). The windings of the transformer would be connected as in the machine, instead of the inductances of the machine. The other side of the transformer could (with appropriate star or delta connection) z. B. connected to a three-phase network. A zero system described below in the phase currents of a transformer are also conceivable and feasible.

The object according to the invention is furthermore achieved by a method for operating the circuit arrangement according to the invention, wherein the half bridges are controlled or regulated such that a zero system of the current is adjusted such that the voltage at the first capacitor can be adjusted. Advantageously, the voltage at the first capacitor is set smaller than the voltage at the second capacitor.

The zero system ( I _G ) is the weighted sum of the instantaneous values of the phase currents ( I _P ). The weighting is typically one-third for three phases. This proportion of current is generated so that it is the same at any time in each phase of the electric machine. This is basically possible for each DC and AC component and their superposition.

The electric machine can also be controlled or regulated via the switching elements of the bridges so that there is an electrical zero system. Alternatively, if z. If, for example, the desired operating state of the electrical machine does not permit this, the aim is to control the zero system to zero.

Advantageously, the current through the phases ( I _P ) are set so that by means of the zero system of the current ( I _G ) the operating characteristics of the DC controller are improved. However, the current of the zero system generates ohmic losses (which one has previously tried to avoid), but no rotating field. The current is not necessarily tried to zero to control, but the current of the zero system is not magnetically effective.

The first capacitor experiences only the effect of the current component of the zero system, which causes an additional voltage change. As a result, energy at the first capacitor can be removed or fed, depending on the phase position or operating mode of the electric machine, d. H. depending on whether motor or generator operation. A return of energy is possible, for. B. during braking.

Alternatively or additionally, a smaller dimensioning of the actuator is possible due to the lower voltage drop across the first capacitor.

Alternatively or additionally, energy is interchangeable between the intermediate circuits.

In other words, the zero system of the current in the machine can be used for control purposes of the circuit.

The voltages of the capacitors can be set or regulated individually. Advantageously, an unwanted increase in the voltages of the capacitors in some operating ranges can no longer occur because the voltages can be kept at a constant level. Specifically, the average voltage remains constant.

Furthermore, the energy flow between different DC sources and the three-phase or multi-phase machine can be adjusted. Furthermore, the already mentioned advantage of reducing the component costs (mass / volume, costs) is made possible.

In a particular embodiment, in contrast to the described method for operating the circuit arrangement according to the invention, in a likewise described arrangement on the negative side of the half-bridges are controlled or regulated so that a zero system of the current is adjusted so that the voltage set on the second capacitor can be. In this case, advantageously, the voltage at the second capacitor is set smaller than the voltage at the first capacitor.

In a particular embodiment of the method for operating a circuit arrangement with a plurality of DC controllers, the DC controller and the one or more further DC controllers are operated out of phase. Ideally, the offset between two adjacent phases is 360 ° divided by the number of DC controllers.

The switching elements of the DC controller can z. B. individually switched by a microcontroller drive or driven and therefore in any desired phase offset.

With a total of two DC controllers, the currents through the two DC controllers would be summed up with a 180 ° phase shift. The individual ripple currents cancel each other out, in the ideal case completely. In practice, a significant reduction of the resulting current ripple is made possible. The optimum phase shift for several DC controllers is calculated using the formula: 360 ° / number of DC controllers.

Advantageously, the components involved can be dimensioned by this control with lower component values, since the current load is lower. Furthermore, can be controlled by the associated control method all degrees of freedom of the circuit (DC link voltages, machine and inductor currents).

Embodiments of the invention are explained below with reference to the drawings.

• 1 die erfindungsgemäße Schaltungsanordnung,
• 2 eine Schaltungsanordnung mit mehrphasigem DC-Steller,
• 3 eine Schaltungsanordnung mit mehreren Stromversorgungen,
• 4a eine Schaltungsanordnung mit dem DC-Steller auf der negativen Seite,
• 4b zusätzlich mit mehrphasigem DC-Steller,
• 4c zusätzlich mit mehreren Stromversorgungen.

Show it:

• 1 the circuit arrangement according to the invention,
• 2 a circuit arrangement with multiphase DC controller,
• 3 a circuit arrangement with several power supplies,
• 4a a circuit arrangement with the DC adjuster on the negative side,
• 4b additionally with multiphase DC controller,
• 4c additionally with several power supplies.

In 1 a circuit according to the invention is shown, in addition to a power supply, the voltage U _q provides and shows a 3 phase electric machine.

As already explained, the voltage source, the DC-controller S who is a thrush L includes, the DC link capacitors C1 and C2 , the half bridges B1 and B2 and the electric machine M electrically connected together, as shown.

The DC controller S is shown here as an up-converter. In principle, other types are possible in which as well as the aforementioned advantages can be achieved.

DC regulator S and bridges B1 and B2 usually have diodes, as shown, the effect and purpose of which is known in this place to the expert and are therefore not explained in detail.

The power connections are located adjacent to the power supply Q , These are not shown because they act as a short circuit electrically. Mechanically, they can, for. B. be designed as a connector.

The DC link ZK here form only the two capacitors C1 and C2 out. Usually, an intermediate circuit is the area or the location at which several power electronic systems are coupled. A Spannungszwischenkreisglättung can take place by capacitors. It is called bipartite because two capacitors are used.

The two half bridges B1 and B2 together form a full bridge, over which every phase of the electric machine M is controlled in a known manner. The bridge is operated asymmetrically.

The core of the circuit is a two-part DC link ZK with two capacitors in series C1 and C2 , A lower potential point U _U (if necessary, also an upper one U _O , please refer 4 ) is used as a common reference point for DC / DC converters (DC controllers) S and the two three-phase bridges B1 and B2 or multi-phase bridges defined. The DC / DC converter S is represented by one (or more, see 2 and 3 ) Half-bridge (s) with choke (s) L formed, wherein the half-bridge only at one of the two capacitors (here at the first capacitor C1 ) and thus only at a partial voltage U _C1 of the DC link ZK connected. bridge B1 , one of the two three-phase bridge circuits or multi-phase (half) bridges B1 and B2 , is at the external potential points, ie the upper and lower potential, with the sum voltage U _C1 + U _{C2 of} the intermediate circuit ZK , connected. The second bridge B2 is compared to the DC / DC converter S other capacitor (here C2) with the potential points inside and below or analogously above, ie the middle U _M and lower potential U _U , connected.

The bridges B1 . B2 are controlled so that, inter alia, a desired operating state of the machine M established. It flows through the individual phases P1 . P2 . P3 The current I _P in sum, to a zero system of the stream I _G results. According to the invention, the circuit can use this as a zero system for voltage regulation of the DC link ZK use.

Assuming a quasi-stationary, symmetrical operation, a bridge is taken B1 . B2 , from the terminals of the power supply only a DC (averaged over a clock period). The power supply Q can in generator operation of the electric machine M as a power sink, z. B. for charging the battery to be operated. It can therefore be regarded as DC sink with respect to these terminals.

By the associated control method can from the three-phase bridges B1 . B2 streams I _P . I _G imprinted in such a way that in conjunction with the control of the primary-side DC controller S the tensions U _C1 . U _C2 all capacitors C1 . C2 can be adjusted, even if no active power from the machine M is removed.

The invention additionally relates to 1 Still further dependent embodiments, which are shown in the following figures.

In 2 a circuit arrangement is shown with multiphase DC controller, which unlike the circuit of 1 several parallel DC controllers S and S2 shows. The connection points are the same. The entire transmitted energy can be distributed to both controllers. This is done by appropriate control of the switching elements of the half-bridge of each DC controller S ,

This circuit arrangement can additionally be operated with a special method. It can be several or all of the parallel DC controller S . S2 out of phase a single power supply Q operate as already described.

In 3 is a circuit arrangement with multiple power supplies Q . Q2 shown as in the circuit of 2 have multiple DC controller, in contrast to the input side are different power supplies Q . Q2 connected. Each power supply is connected to its own DC controller S . S2 connected, the output side are connected to the same potential, as shown the upper potential U _O and the middle potential U _M ,

By appropriate control of the switching elements of the DC controller S . S2 Now multiple sources can be operated, which can influence from which source how much energy is retrieved or fed back.

In 4a a circuit arrangement is shown with the DC adjuster on the so-called negative side of the circuit, in contrast to the position of the DC adjuster S of the circuit 1 referred to as a positive page.

It is then also the position, or connection of the second half-bridge B2 connect at another position, namely such that the one capacitor of the DC link ZK which is not bridged by the DC adjuster S is bridged. In addition, the DC adjuster can also act on the negative connections of the three-phase bridges so that the positive connections are combined

In 4b is the concept out 2 in the of 4a integrated. The DC controller S is connected on the negative side, in addition, the DC controller is a multi-phase DC controller consisting of several individual DC controllers S . S2 ,

In 4c is the concept out 3 in the of 4a integrated. Several power supplies Q . Q2 are each a DC adjuster S . S2 connected, the DC controllers are connected on the negative side.

LIST OF REFERENCE NUMBERS

Q

power supply

Q2

additional power supply

U _q

Voltage of the voltage source / power supply

S

DC regulator

S2

additional DC controllers

L

throttle

ZK

DC

C1

first capacitor

C2

second capacitor

U _C1

Voltage at the first capacitor

U _C2

Voltage at the second capacitor

B1

first half bridge

B2

second half bridge

M

electric machine

P1, P2, P3

three phases

I _P

Current through the phases

I _G

Zero system of the stream

U _U

lower potential

U _M

medium potential

U _O

upper potential

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 102014005124 A1 [0009]
• DE 102014002592 A1 [0010]

Cited non-patent literature

• M. Gommeringer, F. Kammerer, J. Kolb, M. Braun, "Novel DC-AC Converter Topology for Multilevel Battery Energy Storage Systems", PCIM Europe 2013, Nuremberg, 14.-16. May 2013 [0006]
• J. Kolb, M. Gommeringer, Karlsruhe Institute of Technology, "Circuitry and Methods for the Exchange of Electrical Energy" [0009]
• M. Gommeringer, A. Schmitt, J. Kolb, Karlsruhe Institute of Technology, "Circuit arrangements and methods for tapping electrical power from multiple module strings" [0010]

Claims (10)

Circuit arrangement for operating an electrical machine (M) or a transformer arrangement with at least 3 phases (P1, P2 P3), comprising: - connections for a power supply (Q); - A DC-controller (S), the input side of which is connected to a terminal of the power supply (Q) and the output side, a first capacitor (C1) of a two-part DC link (ZK) bridged; - The two-part intermediate circuit (ZK) consisting of the first (C1) and a second capacitor (C2), which are connected in series with each other, so that - formed between the two capacitors (C1, C2), a mean potential (U _M ) is, - at the other end of the first capacitor (C1) an upper potential (U _O ) is formed and - at the other end of the second capacitor (C2), a lower potential (U _U ) is formed; the second terminal for the power supply (Q), which is connected to the lower potential (U _U ); - For each phase (P1, P2, P3) of the electrical machine (M) or the transformer assembly: - A first half-bridge (B1) whose outer terminals are respectively connected to the upper (U _O ) and the lower potential (U _U ) , - a second half bridge (B2) whose outer terminals are respectively connected to the lower potential (U _U ) and the middle potential (U _M ), wherein the center taps of the two half bridges (B1, B2) for connecting the inductive load of the respective Phase (P1, P2, P3) of the electrical machine (M) or transformer arrangement serve. Circuit arrangement according to Claim 1 , characterized in that the DC controller (S) comprises: - a choke (L) which is connected on the one hand to the one terminal of the power supply (Q) and on the other hand to the center tap of a half-bridge of the DC adjuster, - the half-bridge of DC adjuster (S), whose outer terminals bridge the first capacitor, that is connected to the upper (U _O ) and middle potential (U _M ). Circuit arrangement according to one of the preceding claims, characterized in that the circuit arrangement comprises one or more further DC controllers (S2) which are connected in parallel to the DC controller (S). Circuit arrangement according to one of the preceding claims, characterized in that the circuit arrangement comprises one or more further DC controllers (S2) which are connected on the input side to a further connection for a further power supply (Q2) and the output side parallel to the DC controller (S) are connected. Circuit arrangement according to one of the preceding claims, characterized in that the DC adjuster (S) on the output side bridges the second capacitor (C2) instead of the first capacitor (C1), the second connection for the power supply (Q) instead of the lower (U _U ) is connected to the upper potential (U _O ) and the second half-bridge (B2) of each phase (P1, P2, P3) is connected to the upper potential (U _O ) instead of the lower potential (U _U ). Circuit arrangement according to one of the preceding claims, characterized in that the one (S) or a plurality of further DC regulators (S2) bridge one of the two capacitors of the intermediate circuit and the second half-bridge (B2) the other of the two capacitors of the intermediate circuit. Circuit arrangement according to one of the preceding claims, characterized in that the electrical machine or transformer arrangement comprises more than 3 phases. Method for operating a circuit arrangement according to Claim 1 , characterized in that the half bridges (B1, B2) are controlled or regulated such that a zero system of the current (I _G ) is set such that the voltage across the first capacitor (U _C1 ) is lower than the voltage across the second capacitor (U _C2 ). Method for operating a circuit arrangement according to Claim 5 , characterized in that the half bridges (B1, B2) are controlled or regulated such that a zero system of the current (I _G ) is set such that the voltage across the second capacitor (U _C2 ) is lower than the voltage at the first capacitor (U _C1 ). Method for operating a circuit arrangement according to Claim 3 or 4 , characterized in that the DC-controller (S) and the one or more further DC-controllers (S2) are operated out of phase, ideally with the displacement 360 ° divided by the number of DC-controllers.

Images