EP1961105A2 - Circuit arrangement and method for determining at least one electric current in a bridge circuit operating an electric machine - Google Patents

Circuit arrangement and method for determining at least one electric current in a bridge circuit operating an electric machine

Info

Publication number
EP1961105A2
EP1961105A2 EP06830191A EP06830191A EP1961105A2 EP 1961105 A2 EP1961105 A2 EP 1961105A2 EP 06830191 A EP06830191 A EP 06830191A EP 06830191 A EP06830191 A EP 06830191A EP 1961105 A2 EP1961105 A2 EP 1961105A2
Authority
EP
European Patent Office
Prior art keywords
bridge
circuit
current
circuit arrangement
electrical machine
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP06830191A
Other languages
German (de)
French (fr)
Inventor
Tero Jaervelaeinen
Gilles Schmitt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP1961105A2 publication Critical patent/EP1961105A2/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter

Definitions

  • the invention relates to a circuit arrangement for determining at least one electrical current in a bridge circuit operating an electrical machine, which has at least two bridge branches which are connected to one another by means of connecting lines, one of the connecting lines the beginnings of the bridge branches and another of the connecting lines the ends of the Bridge branches connects together.
  • Such a circuit arrangement for determining at least one electrical current in a bridge circuit operating an electrical machine is known.
  • the bridge circuit is supplied with a constant DC voltage, for example, and forms an intermediate circuit for operating an electrical machine.
  • the electrical machine can be, for example, a multi-phase electric motor that is electronically commutated, for example, by controllable electrical circuit devices of the bridge circuit.
  • the electrical circuit devices connect the electrical machine to the DC voltage source in a predetermined sequence.
  • Electrical machines clocked in this way, such as electronically commutating direct current motors are used in many technical fields, including frequently in motor vehicles. A current measurement is often required, which is used, for example, to monitor, control or switch off when a limit value is exceeded.
  • low-resistance shunts with a downstream differential amplifier for signal processing are used to measure the current.
  • a conventional current control of a three-phase electrical machine at least two phase currents must be measured. If additional overcurrent protection is required, a number of shunts corresponding to the number of phases of the electrical machine is required.
  • a shunt is arranged in a bridge branch. Together with signal processing, the shunts represent a major cost factor.
  • a current measurement with only one shunt which is connected in the intermediate circuit between the bridge circuit and the voltage supply or the intermediate circuit capacitor, is also possible.
  • a current measurement is only possible if at least one electrical control element (for example a unipolar transistor) on the side of the bridge circuit facing the shunt and at least one electrical control element of another bridge branch on the side of the bridge circuit facing away from the shunt is turned on , otherwise no current flows through the shunt.
  • a current that only flows in the electrical machine and the bridge circuit that operates the electrical machine (free-wheeling) cannot be determined with this measuring arrangement.
  • the circuit arrangement according to the invention with the features mentioned in claim 1 offers the advantage that current measurement in the electrical machine is also possible in a freewheeling mode.
  • this circuit arrangement gives you the option of changing the current over time in the electrical machine when it is switched off, i.e. when the electrical is disconnected from the power supply but is in free-running mode Machine to control.
  • the part of the current flowing through the shunt is measured directly as a function of time.
  • the possibilities of this measurement arrangement in operation are not restricted compared to those of a conventional measurement arrangement. If several shunts are used, a simultaneous current measurement can be carried out; if only one shunt is used, for example, in a three-phase electrical machine, a current measurement of all branches of the electrical machine can be carried out in a timely manner.
  • each bridge branch has at least two electrical control elements arranged in series, which have a center tap between them.
  • Bridge branches of a bridge circuit constructed in this way have all the components which are required for controlling an electrically commutated electrical machine.
  • the electrical machine is designed as a three-phase motor or three-phase generator.
  • This can be, for example, a conventional three-phase motor, a brushless direct current motor (BLDC motor), which can be designed as a permanent magnet synchronous motor or asynchronous motor, and correspondingly constructed generators.
  • the machines mentioned can preferably be connected in a star connection.
  • the electrical control elements are designed as transistors, in particular field-effect transistors. Unipolar transistors are characterized by extremely low control currents, which can also be controlled by control units that have only very low output powers. In the case of power transistors, the switchable currents can be selected to be very high. At the same time, the switching times for the transistors mentioned are very short.
  • the bridge circuit is connected to an intermediate circuit operated with direct voltage. By commutating by means of the electrical control elements in the bridge circuit, the electrical machine can be operated with the DC voltage of the intermediate circuit. It is expedient if an intermediate circuit capacitor is arranged parallel to the bridge branches of the bridge circuit. This intermediate circuit capacitor ensures that a high current can be supplied sufficiently quickly.
  • the invention further relates to a method for determining at least one electric current in a bridge circuit which operates an electrical machine and has at least two bridge branches which are connected to one another by means of connecting lines, one of the connecting lines showing the beginnings of the two bridges. ge and another of the connecting lines connects the ends of the bridge branches together. It is provided that at least one current measurement is carried out in at least one of the connecting lines. With this method it is possible to measure a timely measurement of all currents of the electrical machine and their phase relationships. A current measurement is also possible in a freewheeling mode.
  • each bridge branch has at least two electrical control elements arranged in series, which are controlled by a switching unit.
  • This switching unit can be used on the one hand as a commutation device for operating the electrical machine, but it can also bring about a switching state which can be used, in particular, for the timely measurement of the currents of the electrical machine, even in free-running mode.
  • control of the control element takes place as pulse width modulation.
  • an electrical current of the electrical machine can also be measured in a freewheeling mode.
  • the electrical control elements located opposite the shunt in the bridge circuit are high-resistance, and the electrical control elements on the side of the shunt - that is to say in its vicinity - are switched to be conductive.
  • the shunt is arranged, for example, in the connecting line between a first bridge branch and a second bridge branch and, in free-running operation, measures the circulating current which flows through the parts of the first and second bridge branches involved and the electrical machine.
  • FIG. 1 shows a circuit arrangement for determining at least one electric current in a bridge circuit operating a three-phase electrical machine
  • FIG. 2 shows the time-dependent course of pulse width modulation signals for controlling the transistors T1 to T6 over four clock periods in a first time period
  • Figure 4 shows the circuit arrangement with registered circuit currents in the bridge circuit during a freewheel.
  • FIG. 1 shows a block diagram of a circuit arrangement 1 with a bridge circuit 4 that operates an electrical machine 3 designed as a star-connected three-phase motor 2.
  • the bridge circuit 4 has three bridge branches 5, 5 ′, 5 ′′ which are connected to one another by means of connecting lines 6, 6 ′, a shunt 7 being arranged in the connecting line 6 between the first bridge branch 5 and the second bridge branch 5 ′ is connected to the input of a measuring device 8.
  • the output of the measuring device 8 is connected to the input of a control unit 9 which receives a measurement signal from the measuring device 8 and which controls a switching unit 11 designed as a pulse width modulation unit 10.
  • the switching unit 11 controls via its not shown Outputs as transistors T1 to T6 - in particular field effect transistors 13 - control elements 12, 12 ' the bridge circuit 4.
  • a DC voltage source 15 of an intermediate circuit 16 is arranged parallel to the bridge branches 5, 5 ', 5 "of the bridge circuit 4, the intermediate circuit 16 having an intermediate circuit capacitor 14 connected in parallel with the DC voltage source 15.
  • the intermediate circuit 16 supplies the bridge circuit 4 for operating the electrical machine 3, the electrical machine being operated in a commutating manner by switching the control elements 12, 12 '.
  • the measuring device 8 is composed of a differential amplifier 19 and an analog / digital converter 20. which are arranged in series.
  • a current to be measured flows through the Shu nt 7, so that there is a preferably low voltage equivalent to the current, which is amplified by the downstream differential amplifier 19 and then converted via the analog / digital converter 20 into a digital value proportional to the current, which can be read out by the control unit 9.
  • An additional voltage (offset voltage) can be added to the output signal of the differential amplifier 19 by an analog adder, not shown.
  • the value of the measured current is fed to the control unit 9, which effects the switching of the control elements 12, 12 'by means of the switching unit 11.
  • the circuit arrangement 1 is used to operate the electrical machine 3 designed as a three-phase motor 2.
  • the control elements 12, 12 'designed as transistors T1 to T6 are controlled by the control unit 9 via the switching unit 11 such that the electrical machine 3 is operated in an electrically commutating manner.
  • all three currents ia, ib, ic are machine 3 and their phase relationships with one another are determined in succession by time-dependent current measurements during operation.
  • the switching states of the transistors T1 to T6 necessary for current measurement with the shunt 7 will be discussed below.
  • the measured currents can be used as control variables in order, for example, to implement a sinusoidal energization of the three-phase motor 2 with the circuit arrangement 1.
  • the feedback effect of the current measured at the shunt 7 creates a control circuit 21.
  • the control unit 9 is in this case a controller 22, the pulse width modulation unit 10 as an actuator 23, the bridge circuit 4 with the electrical machine 3 as a control system 24 and the measuring unit 8 designed as a measuring element 25 of the control circuit 21.
  • the waveforms are generated, for example, by pulse width modulation.
  • the necessary data such as pulse duration and pulse width are output by the control unit 9, which compares the current with a desired value, as a control variable to the pulse width modulation unit 10.
  • the pulse width modulation unit 10 uses this to generate the pulse width modulation signals for controlling the transistors T1 to T6. These signals for driving the transistors T1 to T6 are each shown in FIG. 2 and FIG. 3 over four clock cycles.
  • FIG. 2 shows the switching states of the transistors T1 to T6 of the bridge circuit 4 shown in FIG. 1 as a function of time.
  • the time is plotted on the abscissa, the switching states on the ordinate.
  • a value of zero on the respective ordinate corresponds to a non-conductive state of the corresponding transistor T1 to T6, while that of zero different value corresponds to a conductive state of the corresponding transistor T1 to T6.
  • the transistors which are arranged in a bridge branch (T1 and T2 in the first bridge branch 5, T3 and T4 in the second bridge branch 5 ′ and T5 and T6 in the third bridge branch 5 ′′) are connected in phase opposition to one another at any time, so that one transistor is turned on when the other transistor of the same bridge branch 5, 5 ', 5 "is turned off and vice versa.
  • T1, T4 and T5 are switched on, so that only the current ib flows through T4 and the shunt 7 and is measured.
  • T2, T3 and T6 are switched on, so that only the currents ia and ic flow through the transistors T2 and T6, of which only the current ic also flows through the shunt 7 and is measured.
  • FIG. 3 shows the switching states of the transistors T1 to T6 of the bridge circuit 4 in another time range in which the transistors T1 to T6 are switched in such a way that the star-connected three-phase motor 2 is in freewheeling.
  • the transistors T1, T3, T5 on the side of the bridge circuit 4 facing away from the shunt 7 are non-conductive and the transistors T2, T4, T6 on the side of the bridge circuit 4 facing the shunt 7 are turned on, so that the electrical machine 3 is freewheeling in these time ranges, as a result of which circular currents are formed which flow through the connecting line 6 in which the shunt 7 is arranged.
  • FIG. 3 shows the switching states of the transistors T1 to T6 of the bridge circuit 4 in another time range in which the transistors T1 to T6 are switched in such a way that the star-connected three-phase motor 2 is in freewheeling.
  • the circuit 4 shows the circuit arrangement 1 during the time range at the end or at the beginning of the clock cycles shown in FIG. 3.
  • the three circulating currents K1 (dash), K2 (dash-dot-dot), K3 (dash-dot) flow in the electrical machine 3 and in the parts of the bridge branches 5, 5 ′, 5 ′′ in which the switched transistors are located.
  • the circuit current K1 flows through the transistor T2, the winding phases 18 and 18 ", the transistor T6 and the shunt 7;
  • the circuit current K2 flows through the transistor T2, the winding strands 18 and 18 ', transistor T4 and shunt 7;
  • the circuit current K3 flows through the transistor T4, the winding phases 18 'and 18 "and the transistor T6. Since only the circuit currents K1 and K2 flowing through the transistor T2 flow through the shunt 7, the current becomes with this connection of the transistors T1 to T6 generally measured directly.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
  • Control Of Electric Motors In General (AREA)
  • Control Of Direct Current Motors (AREA)

Abstract

The invention relates to a circuit arrangement (1) for determining at least one electric current in a bridge circuit (4) which operates an electric machine (3) and is provided with at least two bridge arms (5, 5', 5'') that are interconnected by means of connecting wires (6, 6'), one of said connecting wires (6) interconnecting the beginnings of the bridge arms (5, 5', 5'') and another one of said connecting wires (6') interconnecting the ends of the bridge arms (5, 5', 5''). At least one shunt (7) is disposed in at least one of the connecting wires (6, 6') in order to determine the current. The invention also relates to a corresponding method.

Description

ROBERT BOSCH GMBH, 70442 STUTTGART  ROBERT BOSCH GMBH, 70442 STUTTGART
Schaltungsanordnung und Verfahren zur Ermittlung mindestens eines elektrischen Stromes in einer eine elektrische Maschine betreibenden Brückenschaltung Circuit arrangement and method for determining at least one electrical current in a bridge circuit operating an electrical machine
Die Erfindung betrifft eine Schaltungsanordnung zur Ermittlung mindestens eines elektrischen Stromes in einer eine elektrische Maschine betreibenden Brückenschaltung, die mindestens zwei Brückenzweige aufweist, die mittels Verbindungsleitungen miteinander ver- bunden sind, wobei eine der Verbindungsleitungen die Anfänge der Brückenzweige und eine weitere der Verbindungsleitungen die Enden der Brückenzweige miteinander verbindet. The invention relates to a circuit arrangement for determining at least one electrical current in a bridge circuit operating an electrical machine, which has at least two bridge branches which are connected to one another by means of connecting lines, one of the connecting lines the beginnings of the bridge branches and another of the connecting lines the ends of the Bridge branches connects together.
Stand der Technik State of the art
Eine derartige Schaltungsanordnung zur Ermittlung mindestens eines elektrischen Stromes in einer eine elektrische Maschine betreibenden Brückenschaltung ist bekannt. Die Brückenschaltung wird zum Beispiel mit einer konstanten Gleichspannung versorgt und bil- det einen Zwischenkreis zum Betrieb einer elektrischen Maschine. Bei der elektrischen Maschine kann es sich zum Beispiel um einen mehrphasigen Elektromotor handeln, der zum Beispiel durch ansteuerbare elektrische Schaltungseinrichtungen der Brückenschaltung elektronisch kommutiert wird. Dabei verbinden die elektrischen Schaltungseinrichtungen die elektrische Maschine in einer vorbestimmten Folge mit der Gleichspannungsquelle. Derartig getaktete elektrische Maschinen wie zum Beispiel elektronisch kommutierende Gleichstrommotoren werden auf vielen technischen Gebieten, unter anderem auch häufig in Kraftfahrzeugen verwendet. Dabei ist oft eine Strommessung erforderlich, die zum Bei- spiel zur Überwachung, Regelung oder Abschaltung bei Überschreitung eines Grenzwertes genutzt wird. Üblicherweise setzt man zur Messung des Stromes niederohmige Shunts mit einem nachgeschalteten Differenzverstärker zur Signalaufbereitung ein. Für eine konventionelle Stromregelung einer dreiphasigen elektrischen Maschine müssen mindestens zwei Phasenströme gemessen werden. Soll zusätzlich ein Überstromschutz realisiert werden, braucht man eine der Anzahl der Phasen der elektrischen Maschine entsprechende Anzahl von Shunts. Bei dieser Messanordnung ist jeweils ein Shunt in einem Brückenzweig angeordnet. Die Shunts bilden zusammen mit der Signalaufbereitung einen großen Kostenfaktor. Such a circuit arrangement for determining at least one electrical current in a bridge circuit operating an electrical machine is known. The bridge circuit is supplied with a constant DC voltage, for example, and forms an intermediate circuit for operating an electrical machine. The electrical machine can be, for example, a multi-phase electric motor that is electronically commutated, for example, by controllable electrical circuit devices of the bridge circuit. The electrical circuit devices connect the electrical machine to the DC voltage source in a predetermined sequence. Electrical machines clocked in this way, such as electronically commutating direct current motors, are used in many technical fields, including frequently in motor vehicles. A current measurement is often required, which is used, for example, to monitor, control or switch off when a limit value is exceeded. Usually, low-resistance shunts with a downstream differential amplifier for signal processing are used to measure the current. For a conventional current control of a three-phase electrical machine, at least two phase currents must be measured. If additional overcurrent protection is required, a number of shunts corresponding to the number of phases of the electrical machine is required. In this measuring arrangement, a shunt is arranged in a bridge branch. Together with signal processing, the shunts represent a major cost factor.
Kann auf eine zeitgleiche Strommessung in allen Brückenzweigen verzichtet werden, so ist auch eine zeitnahe Strommessung mit nur einem Shunt, der im Zwischenkreis zwischen der Brückenschaltung und der Spannungsversorgung, beziehungsweise dem Zwischen- kreiskondensator angeschlossen ist, möglich. Bei dieser Anordnung des Shunts ist eine Strommessung nur möglich, wenn mindestens ein elektrisches Steuerelement (zum Beispiel ein unipolarer Transistor) auf der dem Shunt zugewandten Seite der Brückenschaltung und mindestens ein elektrisches Steuerelement eines anderen Brückenzweiges auf der dem Shunt abgewandten Seite der Brückenschaltung leitend geschaltet ist, da sonst über den Shunt kein Strom fließt. Einen Strom, der lediglich in der elektrischen Maschine und der die elektrische Maschine betreibenden Brückenschaltung fließt (Freilauf) kann mit dieser Messanordnung nicht ermittelt werden. Vorteile der Erfindung If there is no need for a simultaneous current measurement in all bridge branches, a current measurement with only one shunt, which is connected in the intermediate circuit between the bridge circuit and the voltage supply or the intermediate circuit capacitor, is also possible. With this arrangement of the shunt, a current measurement is only possible if at least one electrical control element (for example a unipolar transistor) on the side of the bridge circuit facing the shunt and at least one electrical control element of another bridge branch on the side of the bridge circuit facing away from the shunt is turned on , otherwise no current flows through the shunt. A current that only flows in the electrical machine and the bridge circuit that operates the electrical machine (free-wheeling) cannot be determined with this measuring arrangement. Advantages of the invention
Die erfindungsgemäße Schaltungsanordnung mit den im Anspruch 1 genannten Merkmalen bietet demgegenüber den Vorteil, dass eine Strommessung bei der elektrischen Maschine auch bei einem Freilaufbetrieb möglich ist. Neben der Strommessung, die zur Überwachung und Regelung der elektrischen Maschine im Betrieb benötigt wird, erhält man mit dieser Schaltungsanordnung die Möglichkeit, den zeitlichen Stromverlauf innerhalb der elektrischen Maschine im abgeschalteten Zustand, dass heißt bei von der Spannungsversorgung abgetrennter, sich jedoch im Freilaufbetrieb befindlicher elektrischer Maschine, zu kontrollieren. Der über den Shunt fließende Teil des Stroms wird direkt zeitabhängig gemessen. Die Möglichkeiten dieser Messanordnung im Betrieb sind gegenüber denen einer her- kömmlichen Messungsanordnung nicht eingeschränkt. Bei Verwendung von mehreren Shunts kann eine zeitgleiche Strommessung realisiert werden, bei Verwendung von nur einem Shunt lässt sich zum Beispiel bei einer dreiphasigen elektrischen Maschine eine zeitnahe Strommessung aller Zweige der elektrischen Maschine realisie- ren. The circuit arrangement according to the invention with the features mentioned in claim 1 offers the advantage that current measurement in the electrical machine is also possible in a freewheeling mode. In addition to the current measurement required to monitor and control the electrical machine during operation, this circuit arrangement gives you the option of changing the current over time in the electrical machine when it is switched off, i.e. when the electrical is disconnected from the power supply but is in free-running mode Machine to control. The part of the current flowing through the shunt is measured directly as a function of time. The possibilities of this measurement arrangement in operation are not restricted compared to those of a conventional measurement arrangement. If several shunts are used, a simultaneous current measurement can be carried out; if only one shunt is used, for example, in a three-phase electrical machine, a current measurement of all branches of the electrical machine can be carried out in a timely manner.
Nach einer Weiterbildung der Erfindung ist vorgesehen, dass jeder Brückenzweig mindestens zwei seriell angeordnete, elektrische Steuerelemente aufweist, die zwischen sich einen Mittelabgriff auf- weisen. Derart aufgebaute Brückenzweige einer Brückenschaltung weisen alle Komponenten auf, die zur Ansteuerung einer elektrisch kommutierten elektrischen Maschine benötigt werden. According to a further development of the invention, it is provided that each bridge branch has at least two electrical control elements arranged in series, which have a center tap between them. Bridge branches of a bridge circuit constructed in this way have all the components which are required for controlling an electrically commutated electrical machine.
Es ist zweckmäßig, die elektrische Maschine an den Mittelabgriffen der Brückenzweige anzuschließen, um durch Ansteuerung der elektrischen Steuerelemente - sowohl zum Betrieb der Maschine als auch zur Strommessung - ein insbesondere kommutierendes Schalten vornehmen zu können. - A - It is expedient to connect the electrical machine to the center taps of the bridge branches in order to be able to carry out, in particular, commutating switching by controlling the electrical control elements - both for operating the machine and for measuring current. - A -
Nach einer bevorzugten Ausführungsform ist die elektrische Maschine als Drehstrommotor oder Drehstromgenerator ausgebildet. Dabei kann es sich zum Beispiel um einen konventionellen Drehstrommotor, um einen bürstenlosen Gleichstrommotor (BLDC-Motor), der als Permanentmagnet-Synchronmotor oder Asynchronmotor ausgebildet sein kann, sowie um entsprechend aufgebaute Generatoren handeln. Die erwähnten Maschinen können vorzugsweise in Stern-Schaltung geschaltet sein. Nach einer Weiterbildung der Erfindung sind die elektrischen Steuerelemente als Transistoren, insbesondere Feldeffekttransistoren, ausgebildet. Unipolare Transistoren zeichnen sich durch extrem geringe Steuerströme aus, die auch von Steuereinheiten gesteuert werden können, die nur sehr geringe Ausgangsleistungen aufweisen. Bei Leistungstransistoren können die schaltbaren Ströme sehr hoch gewählt werden. Gleichzeitig sind die Schaltzeiten bei den erwähnten Transistoren sehr gering. According to a preferred embodiment, the electrical machine is designed as a three-phase motor or three-phase generator. This can be, for example, a conventional three-phase motor, a brushless direct current motor (BLDC motor), which can be designed as a permanent magnet synchronous motor or asynchronous motor, and correspondingly constructed generators. The machines mentioned can preferably be connected in a star connection. According to a development of the invention, the electrical control elements are designed as transistors, in particular field-effect transistors. Unipolar transistors are characterized by extremely low control currents, which can also be controlled by control units that have only very low output powers. In the case of power transistors, the switchable currents can be selected to be very high. At the same time, the switching times for the transistors mentioned are very short.
Es ist vorteilhaft, wenn die Brückenschaltung an einen mit Gleich- Spannung betriebenen Zwischenstromkreis angeschlossen ist. Durch das Kommutieren mittels der elektrischen Steuerelemente in der Brückenschaltung lässt sich die elektrischen Maschine mit der Gleichspannung des Zwischenkreises betreiben. Es ist zweckmäßig, wenn parallel zu den Brückenzweigen der Brückenschaltung ein Zwischenkreiskondensator angeordnet ist. Dieser Zwischenkreiskondensator sorgt dafür, dass hinreichend schnell ein hoher Strom geliefert werden kann. Die Erfindung betrifft ferner ein Verfahren zur Ermittlung mindestens eines elektrischen Stromes in einer eine elektrische Maschine betreibenden Brückenschaltung, die mindestens zwei Brückenzweige aufweist, die mittels Verbindungsleitungen miteinander verbunden sind, wobei eine der Verbindungsleitungen die Anfänge der Brückenzwei- ge und eine weitere der Verbindungsleitungen die Enden der Brückenzweige miteinander verbindet. Dabei ist vorgesehen, dass in mindestens einer der Verbindungsleitungen mindestens eine Strommessung durchgeführt wird. Mit diesem Verfahren ist es möglich, eine zeitnahe Messung aller Ströme der elektrischen Maschine sowie deren Phasenbeziehungen zu messen. Auch ist bei einem Freilaufbetrieb eine Strommessung möglich. It is advantageous if the bridge circuit is connected to an intermediate circuit operated with direct voltage. By commutating by means of the electrical control elements in the bridge circuit, the electrical machine can be operated with the DC voltage of the intermediate circuit. It is expedient if an intermediate circuit capacitor is arranged parallel to the bridge branches of the bridge circuit. This intermediate circuit capacitor ensures that a high current can be supplied sufficiently quickly. The invention further relates to a method for determining at least one electric current in a bridge circuit which operates an electrical machine and has at least two bridge branches which are connected to one another by means of connecting lines, one of the connecting lines showing the beginnings of the two bridges. ge and another of the connecting lines connects the ends of the bridge branches together. It is provided that at least one current measurement is carried out in at least one of the connecting lines. With this method it is possible to measure a timely measurement of all currents of the electrical machine and their phase relationships. A current measurement is also possible in a freewheeling mode.
Nach einer Weiterbildung der Erfindung ist vorgesehen, dass jeder Brückenzweig mindestens zwei seriell angeordnete, elektrische Steuerelemente aufweist, die von einer Schalteinheit angesteuert werden. Diese Schalteinheit kann zum einen als Kommutierungsvorrichtung zum Betrieb der elektrischen Maschine genutzt werden, sie kann jedoch auch einen Schaltzustand herbeiführen, der insbeson- dere zur zeitnahen Messung der Ströme der elektrischen Maschine, auch im Freilauf verwendet werden kann. According to a further development of the invention, it is provided that each bridge branch has at least two electrical control elements arranged in series, which are controlled by a switching unit. This switching unit can be used on the one hand as a commutation device for operating the electrical machine, but it can also bring about a switching state which can be used, in particular, for the timely measurement of the currents of the electrical machine, even in free-running mode.
Nach einer bevorzugten Ausführungsform erfolgt die Ansteuerung der Steuerelement als Pulsweitenmodulation. According to a preferred embodiment, the control of the control element takes place as pulse width modulation.
Nach einer Weiterbildung der Erfindung ist vorgesehen, dass - wie bereits erwähnt - auch bei einem Freilaufbetrieb ein elektrischer Strom der elektrischen Maschine gemessen werden kann. Bei einer mehrphasigen elektrischen Maschine sind im Freilaufbetrieb die in der Brückenschaltung dem Shunt entfernt gegenüberliegenden elektrischen Steuerelemente hochohmig, die auf der Seite des Shunts - also in seiner Nähe - liegenden elektrischen Steuerelemente leitend geschaltet. Bei einer Brückenschaltung mit drei Brückenzweigen für eine dreiphasige elektrische Maschine ist der Shunt zum Beispiel in der Verbindungsleitung zwischen einem ersten Brückenzweig und einem zweiten Brückenzweig angeordnet und misst im Freilaufbetrieb den Kreisstrom der durch die beteiligten Teile der ersten und zweiten Brückenzweige und die elektrische Maschine fließt. Zeichnungen According to a development of the invention, it is provided that - as already mentioned - an electrical current of the electrical machine can also be measured in a freewheeling mode. In the case of a multi-phase electrical machine, in the freewheeling mode the electrical control elements located opposite the shunt in the bridge circuit are high-resistance, and the electrical control elements on the side of the shunt - that is to say in its vicinity - are switched to be conductive. In the case of a bridge circuit with three bridge branches for a three-phase electrical machine, the shunt is arranged, for example, in the connecting line between a first bridge branch and a second bridge branch and, in free-running operation, measures the circulating current which flows through the parts of the first and second bridge branches involved and the electrical machine. drawings
Die Erfindung wird nachfolgend in einem Ausführungsbeispiel anhand der zugehörigen Zeichnungen näher erläutert. Es zeigen: The invention is explained in more detail in an exemplary embodiment with reference to the accompanying drawings. Show it:
Figur 1 eine Schaltungsanordnung zur Ermittlung mindestens eines elektrischen Stromes in einer eine dreiphasige elektrische Maschine betreibenden Brückenschaltung, Figur 2 den zeitabhängigen Verlauf von Pulsweitenmodulati- ons-Signalen zur Ansteuerung der Transistoren T1 bis T6 über vier Taktperioden in einem ersten Zeitabschnitt, 1 shows a circuit arrangement for determining at least one electric current in a bridge circuit operating a three-phase electrical machine, FIG. 2 shows the time-dependent course of pulse width modulation signals for controlling the transistors T1 to T6 over four clock periods in a first time period,
Figur 3 den zeitabhängigen Verlauf der Pulsweitenmodulations- Signale zur Ansteuerung der Transistoren T1 bis T6 über vier Taktperioden in einem zweiten Zeitabschnitt, 3 shows the time-dependent course of the pulse width modulation signals for controlling the transistors T1 to T6 over four clock periods in a second period,
Figur 4 die Schaltungsanordnung mit eingetragenen Kreisströmen in der Brückenschaltung während eines Freilaufs. Figure 4 shows the circuit arrangement with registered circuit currents in the bridge circuit during a freewheel.
In Figur 1 ist ein Blockschaltbild einer Schaltungsanordnung 1 mit einer eine als sterngeschalteter Drehstrommotor 2 ausgebildeten elektrischen Maschine 3 betreibende Brückenschaltung 4 gezeigt. Die Brückenschaltung 4 weist drei Brückenzweige 5, 5', 5" auf, die mittels Verbindungsleitungen 6,6' miteinander verbunden sind, wobei in der Verbindungsleitung 6 zwischen dem ersten Brückenzweig 5 und dem zweiten Brückenzweig 5' ein Shunt 7 angeordnet ist, der an den Eingang einer Messeinrichtung 8 angeschlossen ist. Der Ausgang der Messeinrichtung 8 ist mit dem Eingang einer Steuereinheit 9 verbunden, die ein Messsignal der Messeinrichtung 8 aufnimmt und die eine als Pulsweitenmodulations-Einheit 10 ausgebildete Schalteinheit 11 steuert. Die Schalteinheit 11 steuert über ihre nicht dargestellten Ausgänge als Transistoren T1 bis T6 - insbesondere Feldeffekt-Transistoren 13 - ausgebildeten Steuerelemente 12,12' der Brückenschaltung 4. Parallel zu den Brückenzweigen 5, 5', 5" der Brückenschaltung 4 ist eine Gleichspannungsquelle 15 eines Zwischenkreises 16 angeordnet, wobei der Zwischenkreises 16 einen der Gleichspannungsquelle 15 parallel geschalteten Zwischenkreis- kondensator 14 aufweist. Der Zwischenkreis 16 versorgt die Brückenschaltung 4 zum Betreiben der elektrischen Maschine 3, wobei die elektrische Maschine durch Schalten der Steuerelemente 12,12' kommutierend betrieben wird. Jeder einzelne Brückenzweig 5, 5', 5" weist zwei seriell angeordnete, elektrische Steuerelemente 12,12' auf, die zwischen sich jeweils einen Mittelabgriff 17 aufweisen, an dem je einer von drei Wicklungssträngen 18, 18', 18" der als sterngeschalteter Drehstrommotor 2 ausgebildeten elektrischen Maschine 3 angeschlossen ist. Die Messeinrichtung 8 setzt sich aus einem Differenzverstärker 19 und einem Analog/Digital-Wandler 20 zusam- men, die seriell angeordnet sind. Ein zu messende Strom fließt durch den Shunt 7, so dass dort eine vorzugsweisegeringe, dem Strom äquivalente Spannung abfällt, die von dem nachgeschalteten Differenzverstärker 19 verstärkt und anschließend über den Analog/Digital-Wandler 20 in einen dem Strom proportionalen Digitalwert umgewandelt wird, der von der Steuereinheit 9 ausgelesen werden kann. Dem Ausgangssignal des Differenzverstärkers 19 kann durch einen nicht dargestellten Analog-Addierer eine zusätzliche Spannung (Offset-Spannung) zugefügt werden. Der Wert des gemessene Stroms wird der Steuereinheit 9 zugeführt, die das Schalten der Steuerelemente 12,12' mittels der Schalteinheit 11 bewirkt. FIG. 1 shows a block diagram of a circuit arrangement 1 with a bridge circuit 4 that operates an electrical machine 3 designed as a star-connected three-phase motor 2. The bridge circuit 4 has three bridge branches 5, 5 ′, 5 ″ which are connected to one another by means of connecting lines 6, 6 ′, a shunt 7 being arranged in the connecting line 6 between the first bridge branch 5 and the second bridge branch 5 ′ is connected to the input of a measuring device 8. The output of the measuring device 8 is connected to the input of a control unit 9 which receives a measurement signal from the measuring device 8 and which controls a switching unit 11 designed as a pulse width modulation unit 10. The switching unit 11 controls via its not shown Outputs as transistors T1 to T6 - in particular field effect transistors 13 - control elements 12, 12 ' the bridge circuit 4. A DC voltage source 15 of an intermediate circuit 16 is arranged parallel to the bridge branches 5, 5 ', 5 "of the bridge circuit 4, the intermediate circuit 16 having an intermediate circuit capacitor 14 connected in parallel with the DC voltage source 15. The intermediate circuit 16 supplies the bridge circuit 4 for operating the electrical machine 3, the electrical machine being operated in a commutating manner by switching the control elements 12, 12 '. Each individual bridge branch 5, 5', 5 "has two electrical control elements 12, 12 'arranged in series, each between them have a center tap 17, to each of which one of three winding phases 18, 18 ', 18 "of the electrical machine 3 designed as a star-connected three-phase motor 2 is connected. The measuring device 8 is composed of a differential amplifier 19 and an analog / digital converter 20. which are arranged in series. A current to be measured flows through the Shu nt 7, so that there is a preferably low voltage equivalent to the current, which is amplified by the downstream differential amplifier 19 and then converted via the analog / digital converter 20 into a digital value proportional to the current, which can be read out by the control unit 9. An additional voltage (offset voltage) can be added to the output signal of the differential amplifier 19 by an analog adder, not shown. The value of the measured current is fed to the control unit 9, which effects the switching of the control elements 12, 12 'by means of the switching unit 11.
Es ergeben sich folgende Funktionen der Schaltungsanordnung 1 : Zunächst wird die Schaltungsanordnung 1 zum Betrieb der als Drehstrommotor 2 ausgebildeten elektrischen Maschine 3 genutzt. Dazu werden die als Transistoren T1 bis T6 ausgebildeten Steuerelemente 12,12' von der Steuereinheit 9 über die Schalteinheit 11 derart angesteuert, dass die elektrische Maschine 3 elektrisch kommutierend betrieben wird. Zur Überwachung und Regelung der elektrischen Maschine 3 werden alle drei Ströme ia, ib, ic in der elektrischen Ma- schine 3 sowie deren Phasenbeziehungen untereinander durch zeitabhängige Strommessungen während des Betriebs nacheinander bestimmt. Auf die zur Strommessung mit dem Shunt 7 nötigen Schaltzustände der Transistoren T1 bis T6 wird nachstehend noch eingegangen. The following functions of the circuit arrangement 1 result: First, the circuit arrangement 1 is used to operate the electrical machine 3 designed as a three-phase motor 2. For this purpose, the control elements 12, 12 'designed as transistors T1 to T6 are controlled by the control unit 9 via the switching unit 11 such that the electrical machine 3 is operated in an electrically commutating manner. To monitor and control the electrical machine 3, all three currents ia, ib, ic are machine 3 and their phase relationships with one another are determined in succession by time-dependent current measurements during operation. The switching states of the transistors T1 to T6 necessary for current measurement with the shunt 7 will be discussed below.
Die gemessenen Ströme können als Regelgrößen genutzt werden um mit der Schaltungsanordnung 1 zum Beispiel eine sinusförmige Bestromung des Drehstrommotors 2 zu realisieren. Durch die Rück- Wirkung des am Shunt 7 gemessenen Stroms entsteht ein Regelkreis 21. Die Steuereinheit 9 ist dabei als Regler 22, die Pulsweitenmodu- lations-Einheit 10 als Stellglied 23, die Brückenschaltung 4 mit der elektrischen Maschine 3 als Regelstrecke 24 und die Messeinheit 8 als Messglied 25 des Regelkreises 21 ausgebildet. Durch die Platzie- rung des Shunts 7 in der Verbindungsleitung 6 der Brückenschaltung 4 ist eine Strommessung und damit eine Regelung auch während einer Freilaufphase der elektrischen Maschine 3 möglich. Der zeitabhängige Verlauf der resultierenden Ströme ia, ib, ic ist in einem Diagramm der Figur 1 dargestellt. Die Kurvenformen werden zum Bei- spiel durch Pulsweitenmodulation generiert. Die dazu notwendigen Daten wie Pulsdauer und Pulsweite werden von der Steuereinheit 9, die den Strom mit einem Sollwert vergleicht, als Steuergröße an die Pulsweitenmodulations-Einheit 10 ausgegeben. Die Pulsweitenmo- dulations-Einheit 10 erzeugt daraus die Pulsweitenmodulations- Signale zur Ansteuerung der Transistoren T1 bis T6. Diese Signale zur Ansteuerung der Transistoren T1 bis T6 sind in der Figur 2 und der Figur 3 jeweils über vier Taktzyklen dargestellt. The measured currents can be used as control variables in order, for example, to implement a sinusoidal energization of the three-phase motor 2 with the circuit arrangement 1. The feedback effect of the current measured at the shunt 7 creates a control circuit 21. The control unit 9 is in this case a controller 22, the pulse width modulation unit 10 as an actuator 23, the bridge circuit 4 with the electrical machine 3 as a control system 24 and the measuring unit 8 designed as a measuring element 25 of the control circuit 21. By placing the shunt 7 in the connecting line 6 of the bridge circuit 4, a current measurement and thus regulation is also possible during a free-running phase of the electrical machine 3. The time-dependent course of the resulting currents ia, ib, ic is shown in a diagram in FIG. 1. The waveforms are generated, for example, by pulse width modulation. The necessary data such as pulse duration and pulse width are output by the control unit 9, which compares the current with a desired value, as a control variable to the pulse width modulation unit 10. The pulse width modulation unit 10 uses this to generate the pulse width modulation signals for controlling the transistors T1 to T6. These signals for driving the transistors T1 to T6 are each shown in FIG. 2 and FIG. 3 over four clock cycles.
Die Figur 2 zeigt die Schaltzustände der in Figur 1 dargestellten Transistoren T1 bis T6 der Brückenschaltung 4 in Abhängigkeit von der Zeit. Die Zeit ist auf der Abszisse abgetragenen, die Schaltzustände jeweils auf den Ordinaten. Ein Wert von Null auf den jeweiligen Ordinaten entspricht einem nichtleitenden Zustand des entsprechenden Transistors T1 bis T6, während der einheitlich von Null ver- schiedene Wert einem leitenden Zustand des entsprechenden Transistors T1 bis T6 entspricht. Die Transistoren, die in einem Brückenzweig angeordnet sind (T1 und T2 im ersten Brückenzweig 5, T3 und T4 im zweiten Brückenzweig 5' und T5 und T6 im dritten Brücken- zweig 5"), sind zu jedem Zeitpunkt jeweils gegenphasig zu einander geschaltet, so dass der eine Transistor leitend geschaltet ist, wenn der andere Transistor des selben Brückenzweigs 5, 5', 5" nichtleitend geschaltet ist und umgekehrt. Zu dem durch die gestrichelte Linie markierten Zeitpunkt während des ersten Taktzykluses sind T1 , T4 und T5 leitend geschaltet, so dass nur der Strom ib über T4 und den Shunt 7 fließt und gemessen wird. Am Ende des ersten Taktzyklus sind T2, T3 und T6 leitend geschaltet, so dass nur die Ströme ia und ic über die Transistoren T2 und T6 fließen, wovon jedoch nur der Strom ic auch über den Shunt 7 fließt und gemessen wird. FIG. 2 shows the switching states of the transistors T1 to T6 of the bridge circuit 4 shown in FIG. 1 as a function of time. The time is plotted on the abscissa, the switching states on the ordinate. A value of zero on the respective ordinate corresponds to a non-conductive state of the corresponding transistor T1 to T6, while that of zero different value corresponds to a conductive state of the corresponding transistor T1 to T6. The transistors which are arranged in a bridge branch (T1 and T2 in the first bridge branch 5, T3 and T4 in the second bridge branch 5 ′ and T5 and T6 in the third bridge branch 5 ″) are connected in phase opposition to one another at any time, so that one transistor is turned on when the other transistor of the same bridge branch 5, 5 ', 5 "is turned off and vice versa. At the point in time marked by the dashed line during the first clock cycle, T1, T4 and T5 are switched on, so that only the current ib flows through T4 and the shunt 7 and is measured. At the end of the first clock cycle, T2, T3 and T6 are switched on, so that only the currents ia and ic flow through the transistors T2 and T6, of which only the current ic also flows through the shunt 7 and is measured.
Die Figur 3 zeigt die Schaltzustände der Transistoren T1 bis T6 der Brückenschaltung 4 in einem anderen Zeitbereich, in dem die Transistoren T1 bis T6 so geschaltet sind, dass sich der sterngeschaltete Drehstrom-Motor 2 im Freilauf befindet. Am Ende eines jeden Takt- zykluses sind die Transistoren T1 , T3, T5 auf der dem Shunt 7 abgewandten Seite der Brückenschaltung 4 nichtleitend und die Transistoren T2, T4, T6 auf der dem Shunt 7 zugewandten Seite der Brückenschaltung 4 leitend geschaltet, so dass sich die elektrische Maschine 3 in diesen Zeitbereichen im Freilauf befindet, wodurch es zur Ausbildung von Kreisströmen kommt, die durch die Verbindungsleitung 6 fließen, in der der Shunt 7 angeordnet ist. Die Figur 4 zeigt die Schaltungsanordnung 1 während des Zeitbereichs am Ende bzw. zu Beginn der in Figur 3 dargestellten Taktzyklen. In der elektrischen Maschine 3 und in den Teilen der Brückenzweige 5, 5', 5" in denen sich die leitend geschalteten Transistoren befinden, fließen die drei eingezeichneten Kreisströme K1 (Strich), K2 (Strich-Punkt-Punkt), K3 (Strich-Punkt). Der Kreisstrom K1 fließt durch den Transistor T2, die Wicklungsstränge 18 und 18", den Transistor T6 und den Shunt 7; der Kreisstrom K2 fließt durch den Transistor T2, die Wicklungs- stränge 18 und 18', den Transistor T4 und den Shunt 7; der Kreisstrom K3 fließt durch den Transistor T4, die Wicklungsstränge 18' und 18" und den Transistor T6. Da nur die über den Transistor T2 fließenden Kreisströme K1 und K2 durch den Shunt 7 fließen, wird bei dieser Beschaltung der Transistoren T1 bis T6 der Strom ia direkt gemessen. FIG. 3 shows the switching states of the transistors T1 to T6 of the bridge circuit 4 in another time range in which the transistors T1 to T6 are switched in such a way that the star-connected three-phase motor 2 is in freewheeling. At the end of each clock cycle, the transistors T1, T3, T5 on the side of the bridge circuit 4 facing away from the shunt 7 are non-conductive and the transistors T2, T4, T6 on the side of the bridge circuit 4 facing the shunt 7 are turned on, so that the electrical machine 3 is freewheeling in these time ranges, as a result of which circular currents are formed which flow through the connecting line 6 in which the shunt 7 is arranged. FIG. 4 shows the circuit arrangement 1 during the time range at the end or at the beginning of the clock cycles shown in FIG. 3. The three circulating currents K1 (dash), K2 (dash-dot-dot), K3 (dash-dot) flow in the electrical machine 3 and in the parts of the bridge branches 5, 5 ′, 5 ″ in which the switched transistors are located. The circuit current K1 flows through the transistor T2, the winding phases 18 and 18 ", the transistor T6 and the shunt 7; the circuit current K2 flows through the transistor T2, the winding strands 18 and 18 ', transistor T4 and shunt 7; the circuit current K3 flows through the transistor T4, the winding phases 18 'and 18 "and the transistor T6. Since only the circuit currents K1 and K2 flowing through the transistor T2 flow through the shunt 7, the current becomes with this connection of the transistors T1 to T6 generally measured directly.

Claims

Patentansprüche Claims
1. Schaltungsanordnung zur Ermittlung mindestens eines elektrischen Stromes in einer eine elektrische Maschine betreibenden Brückenschaltung, die mindestens zwei Brückenzweige aufweist, die mittels Verbindungsleitungen miteinander verbunden sind, wobei ei- ne der Verbindungsleitungen die Anfänge der Brückenzweige und eine weitere der Verbindungsleitungen die Enden der Brückenzweige miteinander verbindet, dadurch gekennzeichnet, dass in mindestens einer der Verbindungsleitungen (6,6') mindestens ein Shunt (7) zur Stromermittlung angeordnet ist. 1. Circuit arrangement for determining at least one electric current in a bridge circuit which operates an electrical machine and has at least two bridge branches which are connected to one another by means of connecting lines, one of the connecting lines being the beginning of the bridge branches and another of the connecting lines being the ends of the bridge branches to one another connects, characterized in that at least one shunt (7) for current determination is arranged in at least one of the connecting lines (6, 6 ').
2. Schaltungsanordnung nach Anspruch 1 , dadurch gekennzeichnet, dass jeder Brückenzweig (5, 5', 5") mindestens zwei seriell angeordnete, elektrische Steuerelemente (12,12') aufweist, die zwischen sich einen Mittelabgriff (17) aufweisen. 2. Circuit arrangement according to claim 1, characterized in that each bridge branch (5, 5 ', 5 ") has at least two serially arranged electrical control elements (12, 12') which have a center tap (17) between them.
3. Schaltungsanordnung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die elektrische Maschine (3) an den Mittelabgriffen (17) der Brückenzweige (5, 5', 5") angeschlossen ist. 3. Circuit arrangement according to one of the preceding claims, characterized in that the electrical machine (3) on the center taps (17) of the bridge branches (5, 5 ', 5 ") is connected.
4. Schaltungsanordnung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Brückenschaltung (4) als Drehstrombrückenschaltung ausgebildet ist. 4. Circuit arrangement according to one of the preceding claims, characterized in that the bridge circuit (4) is designed as a three-phase bridge circuit.
5. Schaltungsanordnung nach einem der vorhergehenden Ansprüche, gekennzeichnet durch eine als Drehstrommotor (2) oder Drehstromgenerator ausgebildete elektrische Maschine (3). 5. Circuit arrangement according to one of the preceding claims, characterized by an electric machine (3) designed as a three-phase motor (2) or three-phase generator.
6. Schaltungsanordnung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Steuerelemente (12,12') als Transistoren, insbesondere Feldeffekttransistoren (13), ausgebildet sind. 6. Circuit arrangement according to one of the preceding claims, characterized in that the control elements (12, 12 ') are designed as transistors, in particular field effect transistors (13).
7. Schaltungsanordnung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Brückenschaltung (4) an einen mit Gleichspannung betriebenen Zwischenstromkreis (16) angeschlossen ist. 7. Circuit arrangement according to one of the preceding claims, characterized in that the bridge circuit (4) is connected to an intermediate circuit (16) operated with direct voltage.
8. Schaltungsanordnung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass parallel zu den Brückenzweigen (5, 5', 5") ein Zwischenkreiskondensator (14) angeordnet ist. 8. Circuit arrangement according to one of the preceding claims, characterized in that an intermediate circuit capacitor (14) is arranged in parallel with the bridge branches (5, 5 ', 5 ").
9. Verfahren zur Ermittlung mindestens eines elektrischen Stromes in einer eine elektrische Maschine betreibenden Brückenschaltung, die mindestens zwei Brückenzweige aufweist, die mittels Verbindungsleitungen miteinander verbunden sind, wobei eine der Verbindungsleitungen die Anfänge der Brückenzweige und eine weitere der Verbindungsleitungen die Enden der Brückenzweige miteinander verbindet, dadurch gekennzeichnet, dass in mindestens einer der Verbindungsleitungen mindestens eine Strommessung durchgeführt wird. 9.Method for determining at least one electrical current in a bridge circuit which operates an electrical machine and has at least two bridge branches which are connected to one another by means of connecting lines, one of the connecting lines connecting the beginnings of the bridge branches and another of the connecting lines connecting the ends of the bridge branches, characterized in that at least one current measurement is carried out in at least one of the connecting lines.
10. Verfahren nach Anspruch 9, dadurch gekennzeichnet, dass jeder Brückenzweig mindestens zwei seriell angeordnete, elektrische Steuerelemente aufweist, die von einer Schalteinheit angesteuert werden. 10. The method according to claim 9, characterized in that each bridge branch has at least two serially arranged electrical control elements which are controlled by a switching unit.
11. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Ansteuerung als Pulsweitenmodulation erfolgt. 11. The method according to any one of the preceding claims, characterized in that the control takes place as pulse width modulation.
12. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass bei einem Freilaufbetrieb ein elektrischer Strom der elektrischen Maschine gemessen wird. 12. The method according to any one of the preceding claims, characterized in that an electrical current of the electrical machine is measured in a freewheeling operation.
EP06830191A 2005-12-07 2006-11-29 Circuit arrangement and method for determining at least one electric current in a bridge circuit operating an electric machine Withdrawn EP1961105A2 (en)

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DE102005058295A DE102005058295A1 (en) 2005-12-07 2005-12-07 Circuit arrangement and method for determining at least one electric current in a bridge circuit operating an electrical machine
PCT/EP2006/069061 WO2007065830A2 (en) 2005-12-07 2006-11-29 Circuit arrangement and method for determining at least one electric current in a bridge circuit operating an electric machine

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