AU2013214528B2

AU2013214528B2 - Elective control of an alternating current motor or direct current motor

Info

Publication number: AU2013214528B2
Application number: AU2013214528A
Authority: AU
Inventors: Manfred Eder; Hans-Jurgen Tolle
Original assignee: Siemens AG; Siemens Corp
Current assignee: Siemens AG
Priority date: 2012-01-30
Filing date: 2013-01-11
Publication date: 2016-03-03
Anticipated expiration: 2033-01-11
Also published as: ES2578612T3; RU2014135328A; WO2013113540A2; WO2013113540A3; BR112014018746A8; KR101654755B1; DE102012201269A1; EP2792061B1; BR112014018746B1; EP2792061A2; BR112014018746A2; AU2013214528A1; RU2579439C2; KR20140119164A

Abstract

The invention relates to a circuit assembly (1) and to a method for elective control of an alternating current motor (3) or direct current motor (2) supplied from a direct voltage source (4). The circuit assembly (1) comprises two converter modules (5, 6) having an equal number of half-bridges (7) and a number of bridge suction throttles (14.1, 14.2, 14.3) corresponding to the number of half-bridges (7) in a converter module (5, 6) and a control unit (12) for actuating the half-bridges (7) of the converter modules (5, 6). The converter modules (5, 6) are operated to control an alternating current motor (3) as an inverter and to control a direct current motor (2) as a direct voltage converter.

Description

1 Description Elective control of an alternating current motor or direct current motor The invention relates to a circuit arrangement and a method for elective control of an alternating current motor or a direct current motor and a use of the method in a submarine. BACKGROUND In submarines, the electrical energy supply is typically provided by means of a direct current network. For this reason, auxiliary drives (e.g. for ventilators, pumps, etc.) in submarines are usually operated with direct current motors which are normally started up via starting resistors. EP 0 178 446 Al discloses a control device for a circuit arrangement in which a motor is fed from a DC voltage source via two semiconductor controllers arranged in parallel to one another. Each of said semiconductor controllers contains a parallel connection of two controllable semiconductor valves having the same forward direction in series with a draining transformer with a center tap. The center taps of the draining transformers of the semiconductor controllers are connected to the ends of a third draining transformer with a center tap which is connected to one pole of the motor. The control device is configured so as to generate clock frequency signals for the semiconductor valves, each with the same control factor, although said clock frequency signals are electrically offset from one another for the two parallel circuit arrangements by 90', in order to operate the motor in speed regions at which a minimum of current ripple can be achieved. 10950870_1 2 US 2006/0043922 Al discloses a motor control system for driving multi-phase dynamoelectric alternating current machines by means of a DC voltage source. The motor control system comprises two inverter modules for generating a multiphase alternating current, which are coupled to an output filter module. Each inverter module has, for each phase of the alternating current, a half-bridge which is formed from two bipolar transistors with an insulated-gate electrode. The two half-bridges of the output filter modules belonging to the same phase are connected together in each case via an interphase transformer of the output filter module. In order to generate the alternating current, the half-bridges of the inverter modules are controlled by means of space vector modulation. It is an object of the present disclosure to substantially overcome, or at least ameliorate, at least one disadvantage of present arrangements. SUMMARY A circuit arrangement according to the present disclosure for elective control of an alternating current motor or a direct current motor comprises two converter modules with the same number of half-bridges, wherein the number of half-bridges of a converter module is at least as great as the number of phases of the alternating current motor. Furthermore, the circuit arrangement comprises a number of bridge interphase transformers which matches the number of half-bridges in a converter module, a control unit for the converter modules, a first series module for the alternating current motor and a second series module for the direct current motor. Each half bridge has a pair of current direction-dependent switch units able to be controlled by the control unit, each comprising an input and an output, the output of a first switch unit of each 10950870_1 3 pair being linked to the input of the second switch unit of the same pair. Furthermore, a half-bridge of a first converter module and a corresponding half-bridge of the second converter module are connected, in each case, by means of a bridge interphase transformer connected between the two half-bridges, to a full bridge. Each bridge interphase transformer has a center tap which can optionally be connected via the first series module to the alternating current motor or via the second series module to the direct current motor. The first series module comprises an alternating current filter, via which the center taps of the bridge interphase transformers can each be coupled to a phase of the alternating current motor. The second series module comprises at least one additional interphase transformer with a center tap which can be coupled to the direct current motor and two outer terminals, each connectable to a center tap of a bridge interphase transformer. A converter module consists of the half-bridges thereof and is not necessarily configured as a separate assembly. An interphase transformer should be understood to mean a smoothing choke with two partial inductances which are magnetically coupled such that currents flowing in the same direction between outer terminals and a center tap counteract each other in their magnetic effect and that a low resulting inductance is therefore produced, whilst currents flowing in opposing directions reinforce one another in their magnetic effect and a large resulting inductance is therefore produced. The circuit arrangement according to some aspects of the present disclosure can be switched over by exchanging just one hardware component, specifically the series module, from the control system of a direct current motor to the control 10950870_1 4 system of an alternating current motor and vice versa. This reduces costs and effort when converting a drive from direct current to alternating current (or vice versa) and is advantageous, in particular, for uses in which such a conversion is required or favorable, for example, in the context of modernizing the drive. The use of interphase transformer circuits advantageously enables the limitation of ripple in the current with which the direct current or alternating current motor is driven. For the driving of a direct current motor, the circuit arrangement can also be used as a DC transformer which, inter alia, replaces an impedance starter and thus advantageously saves, in particular, the energy consumed by the starting resistor thereof and also enables the speed and/or power during operation to be regulated to the value needed by the process, so that further energy is saved because the speed and/or power are no longer set dependent on the voltage of the direct current network, which might possibly vary strongly. In one aspect, the switch units of the converter modules each comprise a bipolar transistor with an insulated-gate electrode, known as an IGBT (= insulated-gate bipolar transistor), the collector of which defines the input of the switch unit and the emitter of which defines the output of the switch unit. Switch units of this type are particularly suitable as current direction-dependent switch units due to the good conducting state behavior, the high blocking voltage, robustness and the almost power-free controllability of an IGBT. A further aspect provides at least one current transformer for detecting a current flowing between a half-bridge of a converter module and the bridge interphase transformer 10950870_1 5 connected thereto, wherein the current transformer is connected to the control unit to communicate the detected current to the control unit. This advantageously makes it possible, during the controlling of a half-bridge by means of the control unit, to take account of the current flowing between the half-bridge and the corresponding bridge interphase transformer. Preferably, the control unit for controlling the switch units of the half-bridges is a microprocessor. This advantageously enables the control of the switch units to be changed in a simple and versatile manner, for example, by loading new software into the microprocessor, in particular when replacing the direct current motor with the alternating current motor or vice versa. 10950870_1 5a With the method according to aspects of the present disclosure for elective control of an alternating current motor or a direct current motor, a circuit arrangement according to the invention is used. The alternating current motor or the direct current motor is fed via the circuit arrangement from a DC voltage source, the first pole of which is connected to the inputs of the first switch units of all the half-bridges and the second pole of which is connected to the outputs of the second switch units of all the half-bridges. Furthermore, either each phase of the alternating current motor is coupled via the first series module to the center tap of a bridge interphase transformer and the converter modules are operated by means of the control unit as an inverter for converting the DC voltage of the DC voltage source into an AC voltage for the alternating current motor, or the direct current motor is connected via the second series module to center taps of the bridge interphase transformers and the converter modules are operated by means of the control unit as a DC-DC converter for converting the DC voltage of the DC voltage source into a DC voltage for the direct current motor. In the method according to some aspects of the circuit arrangement is therefore connected 10950870_1 6 to a DC voltage source and operated as an inverter or a DC-DC converter, depending on whether the motor connected is the alternating current motor or the direct current motor. This advantageously enables the matching of the operating mode of the circuit arrangement to the respective motor. During operation of the converter modules as an inverter, the half-bridges are controlled by means of the control unit preferably according to a space vector modulation such that the AC voltage generated is regulated onto a target voltage space vector of a target AC voltage. The control of the half-bridges according to a space vector modulation advantageously enables a target AC voltage be set very accurately and, in the process, to minimize a current ripple in the alternating current generated, as will be set out in greater detail in the exemplary embodiment described below. Furthermore, cross currents which flow through the bridge interphase transformers between the converter modules are preferably reduced in that the voltage space vectors which are used during the space vector modulation for the generated AC voltages which can be realized by means of different switching states of the half-bridges are alternately set through these different switching states. The reduction of cross currents which flow through the bridge interphase transformers between the converter modules advantageously lessens losses and faults in the generation of the alternating current. The use, with regard to the voltage space vectors, of redundant switching states of the half bridges during space vector modulation is a simple and effective means for suppressing such cross currents and is therefore particularly well suited to the reduction thereof.

7 On connection of the direct current motor to center taps of the bridge interphase transformers, an additional interphase transformer of the second series module is preferably connected via the center tap thereof to an armature of the direct current motor, via a first outer terminal to the center tap of a first bridge interphase transformer and via the second outer terminal to the center tap of a second bridge interphase transformer. Furthermore, the center tap of a third bridge interphase transformer is connected to the field winding of the direct current motor. In this way, through the connection of two bridge interphase transformers to an additional interphase transformer, the ripple in the current flowing through the direct current motor is advantageously further reduced. On operation of the converter modules as a DC-DC converter, first switch units and/or second switch units of mutually corresponding half-bridges of the converter modules are opened and closed temporally offset to one another such that a ripple in a current flowing through the armature of the direct current motor is minimized in that for a target speed of the direct current motor, a control factor of the switch units connected to the first bridge interphase transformer and the second bridge interphase transformer minimizing this current ripple is determined and set by means of the control unit and the switch units connected to the third bridge interphase transformer are controlled such that the target speed is reached by means of the setting of a suitable field current. A control factor of a switch unit should be understood in this context to be a ratio of a duration over which the switch unit is closed within a clock period to the whole clock period. Minimizing the current ripple advantageously lessens the noise generation by the motor.

8 The method according to some aspects of the present disclosure is intended, in particular, for elective control of an alternating current motor or a direct current motor in a submarine. The method according to some aspects of the present disclosure is particularly advantageously suitable for use in submarines because in submarines a particularly low noise operation of motors is required and this is enabled through the use according to the invention of interphase transformer circuits in order particularly to prevent clock frequency noises. Furthermore, it is useful under some circumstances, when modernizing submarines, to replace direct current motors with three-phase motors, in particular asynchronous motors, which is very easily possible with a circuit arrangement according to the invention, as has been shown above. BRIEF DESCRIPTION OF THE DRAWINGS The above-described properties, features and advantages of the invention and the manner in which this is achieved will now be described more clearly and intelligibly with the following description of an exemplary embodiment, set out in more detail, making reference to the drawings. In the drawings: Fig. 1 is a circuit arrangement for the elective control of a three-phase alternating current motor or of a direct current motor during operation with the direct current motor, and Fig. 2 is a circuit arrangement for the selective control of a three-phase alternating current motor or of a direct current motor during operation with the alternating current motor, Fig. 3 is a space vector diagram for the voltage space vector and a target voltage vector which can be applied to 10950870_1 9 the alternating current motor with the circuit arrangement shown in Figs. 1 and 2. Parts which correspond to one another are provided with the same reference signs in the drawings. Figs. 1 and 2 each show a circuit arrangement 1 according to the invention for the elective control of a direct current motor 2 or a three-phase alternating current motor 3 wherein the circuit arrangement 1 is shown, in Fig. 1, in operation with the direct current motor 2 and, in Fig. 2, in operation with the alternating current motor 3. Both the direct current motor 2 and the alternating current motor 3 are fed via the circuit arrangement 1 from a DC voltage source 4. The circuit arrangement 1 comprises two similarly configured converter modules 5, 6, each having three half-bridges 7, each half-bridge 7 comprising a pair of IGBTs 8.1, 8.2. The emitter 9.1 of a first IGBT 8.1 of each pair is connected to the collector 9.2 of the second IGBT 8.2 of the respective pair. The collectors 9.2 of all the first IGBTs 8.1 are connected to the positive pole of the DC voltage source 4 and the emitters 9.2 of all the second IGBTs 8.2 are connected to the negative pole of the DC voltage source 4. Each IGBT 8.1, 8.2 is coupled to an IGBT driver 10 which is supplied with a supply voltage by means of a voltage supply 11 of the respective converter module 5, 6 wherein, for the sake of clarity, in Figs. 1 and 2 a connection to the respective voltage supply 11 is shown for only some IGBT drivers 10 and further connections are merely suggested. An IGBT 8.1, 8.2 and its IGBT driver 10 together form a current direction-dependent switch unit within the context of the invention. The IGBTs 8.1, 8.2 are individually controllable by means of a control unit 12 configured as a microprocessor via their respective IGBT drivers 10, wherein, for the sake of clarity, 10 in Figs. 1 and 2 only some control lines 13 between the control unit 12 and the IGBT drivers 10 are shown and others are merely suggested. In each case, a half-bridge 7 of a first converter module 5 and a corresponding half-bridge 7 of the second converter module 6 are connected, by means of a bridge interphase transformer 14.1, 14.2, 14.3 connected between these two half bridges 7, to a full bridge. Arranged at each connection of a half-bridge 7 to a bridge interphase transformer 14.1, 14.2, 14.3 is a current transformer 15 by means of which a current flowing between the half-bridge 7 and the bridge interphase transformer 14.1, 14.2, 14.3 is detected. The current transformers 15 are each connected to the control unit 12 for transferring the current detected thereby to said control unit 12, wherein, for the sake of clarity, the connections between the control unit 12 and the current transformers 15 are not shown in Figs. 1 and 2. Each bridge interphase transformer 14.1, 14.2, 14.3 has a center tap 16 which can optionally be connected via the first series module 17 to the alternating current motor 3 or via a second series module 18 to the direct current motor 2. The circuit arrangement 1 differs, on operation with a direct current motor 2 or an alternating current motor 3, only in the respective series module 17, 18. In particular, the circuit arrangement 1 can therefore be converted by simple means through the exchange of the series module 17, 18, from operation with the direct current motor 2 to operation with the alternating current motor 3 and vice versa. The first series module 17 comprises an alternating current filter 19, by means of which the center taps 16 of the bridge interphase transformers 14.1, 14.2, 14.3 can each be coupled to a phase of the alternating current motor 3 and, in the case 11 of the operation of the circuit arrangement 1, to the alternating current motor 3. The second series module 18 has an additional interphase transformer 20 which can be coupled via a center tap 16 to the direct current motor 2 and two outer terminals 21.1, 21.2 via which, in each case, one end of the additional interphase transformer 20 can be connected to a center tap 16 of a bridge interphase transformer 14.1, 14.2, 14.3. On operation of the circuit arrangement 1 with the direct current motor 2, a first outer terminal 21.1 of the additional interphase transformer 20 is connected to the center tap 16 of a first bridge interphase transformer 14.1, the second outer terminal 21.2 of the additional interphase transformer 20 is connected to the center tap 16 of a second bridge interphase transformer 14.2 and the center tap 16 of the additional interphase transformer 20 is connected to an armature of the direct current motor 2. The center tap 16 of the third bridge interphase transformer 14.3 is connected to the field winding 22 of the direct current motor 2. On operation of the circuit arrangement 1 with the direct current motor 2, the converter modules 5, 6 are operated by means of the control unit 12 as a DC-DC converter for converting the DC voltage of the DC voltage source 4 into a DC voltage for the direct current motor 2 in accordance with the method known from EP 0 178 446 Al. Herein, the first IGBT 8.1 and/or the second IGBT 8.2 are opened and closed temporally offset from one another such that a ripple in a current flowing through the armature of the direct current motor 2 is minimized. For this purpose, for a target speed of the direct current motor 2, a control factor which minimizes this current ripple is determined and set by means of the control unit 12 for the first and/or second IGBT 8.1, 8.2 connected respectively to the first bridge interphase 12 transformer 14.1 and the second bridge interphase transformer 14.2, and the IGBTs 8.1, 8.2 connected to the third bridge interphase transformer 14.3 are controlled in such a way and consequently the field current is set such that the target speed is reached. During operation of the circuit arrangement 1 with the alternating current motor 3, the converter modules 5, 6 are operated by means of the control unit 12 as an inverter for converting the DC voltage of the DC voltage source 4 into an AC voltage for the alternating current motor 3. In this regard, the IGBTs 8.1, 8.2 are opened and closed temporally offset relative to one another by means of the control unit 12 through a space vector modulation for voltages applied to the alternating current motor 3 such that the voltage applied to the alternating current motor 3 is regulated to a target AC voltage, wherein a current ripple of the generated alternating current and cross currents which flow through the bridge interphase transformers 14.1, 14.2, 14.3 between the converter modules 5, 6 are minimized. This will now be described in greater detail by reference to Fig. 3. The IGBTs 8.1, 8.2 of a half-bridge 7 are opened and closed alternately, so that exactly one of said IGBTs 8.1, 8.2 is always open and the other IGBT 8.1, 8.2 is closed. Each half bridge 7 therefore has two switching states (first IGBT 8.1 is open and second IGBT 8.2 is closed or vice versa). Since the circuit arrangement 1 in the exemplary embodiment shown in Figs. 1 and 2 has a total of six half-bridges 7, there is a total of 26 = 64 different possible switching states for all the half-bridges 7. With regard to the interlinked phase voltages of the respective AC voltages thereby generated, however, many of these switching states are redundant, i.e. there are different switching states of the half-bridges 7 which deliver the same interlinked phase voltages. Overall, 13 there are nineteen different voltage space vectors, each corresponding to different interlinked phase voltages. Fig. 3 shows the resulting space vector diagram D of these nineteen different voltage space vectors which can be generated by means of the half-bridges 7, wherein the three alternating current phases are identified as R, S, T and each node of the space vector diagram D shown in Fig. 3 indicates the end point of a possible voltage space vector extending from the mid-point of the space vector diagram D to the node. A target voltage space vector 23 of a target AC voltage to be set generally lies within a triangle of three nodes 24, 25, 26 surrounding it, which represent the possible voltage space vectors which lie closest to the target voltage space vector 23. By means of the control unit 12, switching states of the half-bridges 7 each of which realizes one of the voltage space vectors corresponding to one of the three nodes 24, 25, 26 are alternately set by means of the space vector modulation, so that the temporal mid value of these realized voltage space vectors gives the target voltage space vector 23. By this means, the clock frequency current ripple of the alternating current generated, and thus also the size of the alternating current filter 19 required, are advantageously minimized. As described above, different switching states of the half bridges 7 are redundant with regard to the voltage space vectors thereby generated. This is utilized to minimize cross currents which flow through the bridge interphase transformers 14.1, 14.2, 14.3 between the converter modules 5, 6. For this purpose, voltage space vectors which belong to redundant switching states are alternately realized through different said switching states during space vector modulation. Although the invention has been illustrated and described in detail with a preferred exemplary embodiment, the invention is not restricted by the example given and other variations can 14 be derived therefrom by a person skilled in the art without departing from the protective scope of the invention.

Claims

1. Circuit arrangement for control of an alternating current motor, comprising - two converter modules with the same number of half bridges, wherein the number of half-bridges of a converter module is at least as great as the number of phases of the alternating current motor, - a number of bridge interphase transformers matching the number of half-bridges in a converter module, - a control unit for the converter modules, - a first series module for the alternating current motor, wherein - each half-bridge has a pair of current direction- dependent switch units, controllable by means of the control unit, each comprising an input and an output, the output of a first switch unit of each pair being linked to the input of the second switch unit of the same pair, - in each case, a half-bridge of a first converter module and a corresponding half-bridge of the second converter module are connected by means of a bridge interphase transformer connected between the two half-bridges to a full bridge, - each bridge interphase transformer has a center tap which can be connected via the first series module to the alternating current motor (3), - the first series module comprises an alternating current filter, by means of which the center taps of the bridge interphase transformers can each be coupled to a phase of the alternating current motor, wherein the circuit arrangement is configured for elective control of an alternating current motor or a direct current motor, 10950930_1 16 wherein the circuit arrangement comprises a second series module for the direct current motor, wherein the center tap of each bridge interphase transformer can optionally be connected via the first series module to the alternating current motor, or via the second series module to the direct current motor, wherein the second series module comprises at least one additional interphase transformer with a center tap which can be coupled to the direct current motor and two outer terminals, each connectable to a center tap of a bridge interphase transformer.

2. The circuit arrangement as claimed in claim 1, wherein the switch units of the converter modules each comprise a bipolar transistor with an insulated-gate electrode, the collector of which defines the input of the switch unit and the emitter of which defines the output of the switch unit.

3. The circuit arrangement as claimed in any one of the preceding claims, further comprising at least one current transformer for detecting a current flowing between a half-bridge of a converter module and the bridge interphase transformer connected thereto, wherein the current transformer is connected to the control unit to communicate the detected current to the control unit.

4. The circuit arrangement as claimed in any one of the preceding claims, further comprising a microprocessor as the control unit for controlling the switch units of the half-bridges. 10950930_1 17

5. A method for elective control of an alternating current motor or a direct current motor by means of a circuit arrangement according to any one of the preceding claims, wherein - the alternating current motor or the direct current motor is fed via the circuit arrangement from a DC voltage source, the first pole of which is connected to the inputs of the first switch units of all the half-bridges and the second pole of which is connected to the outputs of the second switch units of all the half-bridges, and wherein - either each phase of the alternating current motor is coupled via the first series module to the center tap of a bridge interphase transformer and the converter modules are operated by means of the control unit as an inverter for converting the DC voltage of the DC voltage source into an AC voltage for the alternating current motor, - or the direct current motor is coupled via the second series module to the center taps of the bridge interphase transformers and the converter modules are operated by means of the control unit as a DC-DC converter for converting the DC voltage of the DC voltage source into a DC voltage for the direct current motor.

6. The method as claimed in claim 5, wherein during operation of the converter modules as an inverter, the half-bridges are controlled by means of the control unit according to a space vector modulation such that the AC voltage generated is regulated onto a target voltage space vector of a target AC voltage.

7. The method as claimed in claim 6, wherein cross currents which flow through the bridge interphase transformers between the converter modules are reduced in that the voltage space 10950930_1 18 vectors which are used during the space vector modulation for the generated AC voltages which can be realized by means of different switching states of the half-bridges are alternately set through these different switching states.

8. The method as claimed in any one of the claims 5 to 7, wherein on connection of the direct current motor to center taps of the bridge interphase transformers, an additional interphase transformer of the second series module is connected via the center tap thereof to an armature of the direct current motor, via a first outer terminal to the center tap of a first bridge interphase transformer and via the second outer terminal to the center tap of a second bridge interphase transformer and the center tap of a third interphase transformer is connected to the field winding of the direct current motor.

9. The method as claimed in claim 8, wherein, on operation of the converter modules as a DC-DC converter, first switch units and/or second switch units of mutually corresponding half bridges of the converter modules are opened and closed temporally offset to one another such that a ripple in a current flowing through the armature of the direct current motor is minimized in that for a target speed of the direct current motor, by means of the control unit, a control factor of the switch units connected to the first bridge interphase transformer and the second bridge interphase transformer minimizing this current ripple is determined and set and the switch units connected to the third bridge interphase transformer are controlled such that the target speed is reached by means of the setting of a suitable field current. 10950930_1 19

10. Use of the method as claimed in any one of the claims 5 to 9 for elective control of an alternating current motor or a direct current motor in a submarine. Siemens Aktiengesellschaft Patent Attorneys for the Applicant SPRUSON & FERGUSON 10950930_1