CONVERTER WITH REDUNDANT CIRCUIT TOPOLOGY

Abstract

A converter for an aircraft includes an intermediate circuit for providing a DC voltage between a positive line and a negative line, at least two rectifiers connected to the intermediate circuit to produce the DC voltage from input AC voltages and at least two inverters connected to the intermediate circuit to produce AC output voltages from the DC voltage. The DC voltage terminals of the rectifiers are connected to a first series circuit and the DC voltage terminals of the inverters are connected to a second series circuit. The positive line and the negative line of the intermediate circuit are connected on an input side via the first series circuit and on the output side via the second series circuit. At least one of the DC voltage terminals includes a short circuit for short-circuiting terminal contacts by which the DC voltage terminal is connected to the respective series circuit.

Claims

1.-12. (canceled)

13. A converter for an aircraft, said converter comprising: a DC link for providing a DC voltage between a positive line and a negative line; at least two rectifiers connected to the DC link for producing the DC voltage from input AC voltages by DC voltage connections of the rectifiers, said DC voltage connections of the rectifiers being interconnected so as to form a first series connection; at least two inverters connected to the DC link for producing output AC voltages from the DC voltage by DC voltage connections of the inverters, said DC voltage connections of the inverters being interconnected so as to form a second series connection, said positive line and said negative line of the DC link having their input sides connected to one another via the first series connection and said positive line and said negative line of the DC link having their output sides connected to one another via the second series connection; and a short circuit in at least one of the DC voltage connections of the rectifiers or inverters for short-circuiting connection contacts by which the DC voltage connections of the rectifiers and the inverters are connected to the first and second series connections.

14. The converter of claim 13, wherein the short circuit in at least one of the DC voltage connections of the rectifiers or inverters is formed by a first semiconductor switch which connects the connection contacts.

15. The converter of claim 14, wherein the short circuit of at least one of the inverters is formed by a half-bridge with second semiconductor switches which connect the connection contacts, said half-bridge producing one of the output AC voltages, said output AC voltages of the inverter having a third semiconductor switch for blocking a current when the short circuit is closed.

16. The converter of claim 15, wherein each of the first, second and third semiconductor switches is formed by an IGBT or a MOSFET.

17. The converter of claim 15, wherein at least one of the rectifiers and/or at least one of the inverters has the half-bridge with the second semiconductor switches, said converter further including a monitoring device configured to detect a defective second semiconductor switch in the half-bridge such that the half-bridge remains permanently in an electrically conductive state and configured to activate the short circuit of a DC voltage connection which has the defective second semiconductor switch, said defective second semiconductor switch being connected by the DC voltage connection to one of the first or second series connections.

18. The converter of claim 13, wherein the positive line and the negative line in the DC link are connected by a battery.

19. The converter of claim 13, wherein the rectifiers and/or the inverters have each a smoothing capacitor.

20. The converter of claim 17, wherein at least one of the DC voltage connections of the rectifiers or inverters has a decoupling circuit interconnected between one of the connection contacts of the DC voltage connections and the half-bridge of the rectifiers or inverters, said decoupling circuit being configured to block a current.

21. The converter of claim 20, further comprising a control device configured to provide a step-up converter mode or a step-down converter mode for the DC voltage connections which have both a short circuit and a decoupling circuit by alternately connecting the decoupling circuit and the short circuit.

22. An aircraft, comprising: an electric drive motor for driving a propeller of the aircraft; an electric generator; and a converter configured to couple the electric generator to the electric drive motor, said converter including a DC link for providing a DC voltage between a positive line and a negative line, at least two rectifiers connected to the DC link for producing the DC voltage from input AC voltages by DC voltage connections of the rectifiers, said DC voltage connections of the rectifiers being interconnected so as to form a first series connection, at least two inverters connected to the DC link for producing output AC voltages from the DC voltage by DC voltage connections of the inverters, said DC voltage connections of the inverters being interconnected so as to form a second series connection, said positive line and said negative line of the DC link having their input sides connected to one another via the first series connection and said positive line and said negative line of the DC link having their output sides connected to one another via the second series connection, and a short circuit in at least one of the DC voltage connections of the rectifiers or inverters for short-circuiting connection contacts by which the DC voltage connections of the rectifiers and the inverters are connected to the first and second series connections.

23. The aircraft of claim 22, constructed as a fixed-wing aircraft.

24. The aircraft of claim 22, wherein the generator has at least two independent polyphase coil arrangements, said polyphase coil arrangements being connected to a different one of the rectifiers of the converter.

25. The aircraft of claim 22, wherein the electric drive motor has at least two independent polyphase coil arrangements, said polyphase coil arrangements being connected to a different one of inverters of the converter.

Description

[0021] Exemplary embodiments of the invention are described below. In this regard:

[0022] FIG. 1 shows a schematic representation of an embodiment of the converter according to the invention;

[0023] FIG. 2 shows a schematic representation of a shorting circuit according to an embodiment of the converter according to the invention;

[0024] FIG. 3 shows a schematic representation of a further embodiment of the converter according to the invention;

[0025] FIG. 4 shows a schematic representation of a further embodiment of the converter according to the invention with passive rectifiers;

[0026] FIG. 5 shows a schematic representation of an embodiment of the aircraft according to the invention.

[0027] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments are respective individual features of the invention that can be considered independently of one another and that each also develop the invention independently of one another and hence can also be regarded as part of the invention individually or in a combination other than that shown. Furthermore, the embodiments described are also augmentable by further instances of the already described features of the invention.

[0028] In the Figures, elements having the same function are each provided with the same reference symbols.

[0029] FIG. 1 shows a converter 1 with a rectifier arrangement 2, a DC link 3 and an inverter arrangement 4. Via the converter 1, an electric generator 5 and an electric drive motor 6 may be coupled to or interconnected with one another. The arrangement shown in FIG. 1, may, by way of example, be provided in an electrically driven aircraft. The drive motor 6 can be used to drive a propeller of the aircraft. The generator 5 can, by way of example, be driven by an internal combustion engine (not represented).

[0030] The rectifier arrangement 2 of the converter 1 has, in the example shown in FIG. 1, two rectifiers 7 that can have the same design. Each rectifier 7 may be electrically coupled to a generator coil system G1, G2 of the generator 5 via AC voltage lines 8. The generator coil systems G1, G2 are two mutually insulated winding systems for respectively producing a polyphase rotary current, for example a three-phase rotary current. The generator coil systems G1, G2 are each a polyphase coil arrangement. The two generator winding systems G1, G2 may also be provided by two different generators.

[0031] Each rectifier 7 may have, in a manner which is known per se, half-bridges 9 in order to use a respective half-bridge 9 to convert the input AC voltage received via one of the AC voltage lines 8 into a partial voltage 10 in a manner which is known per se. The partial voltage 10 is a DC voltage. The partial voltage 10 can be produced or provided at a DC voltage connection 11 connection contacts 12. In FIG. 1, the rectifiers 7 are in the form of active rectifiers. The half-bridges 9 of the active rectifiers 7 have semiconductor switches 13, only some of which are provided with a reference symbol in FIG. 1 for the sake of clarity. Each rectifier 7 may furthermore have the smoothing capacitor C across which a partial voltage of the DC link 3 is dropped.

[0032] In the case of the rectifier arrangement 2, the DC voltage connections 11 are connected together to form a series connection 14. The series connection 14 connects a positive line 15 and a negative line 16 of the DC link 3 to one another.

[0033] In the case of each rectifier 7, a semiconductor switch S1 is provided that can be used to connect the respective rectifier 7 to the series connection 14 or to render it ineffective in the series connection 14 on the basis of a control signal. To this end, the connection contacts 12 are interconnected via the semiconductor switch S1.

[0034] The semiconductor switch S1 is a shorting circuit for the DC voltage connection 11. Closing the semiconductor switch S1 shorts the connection contacts 12 of the DC voltage connection 11. As a result, the rectifier 7 is ineffective in the series connection 14. Opening the semiconductor switch S1 allows the partial voltage 10 to be provided between the connection contacts 12.

[0035] The DC voltage connection 11 may furthermore have a semiconductor switch S2, which is a decoupling circuit. The semiconductor switch S2 connects one of the connection contacts 12 to the half-bridges 9. Furthermore, the semiconductor switch S2 interconnects the smoothing capacitor C with one of the connection contacts 12. Opening the semiconductor switch S2 blocks, or, if a diode is present, unidirectionally blocks, a flow of current between the half-bridges 9 and the connection contact 12. Equally, a flow of current is blocked between the smoothing capacitor C and the connection contact 12. Closing the semiconductor switch S2 connects the half-bridges to the connection contact 12. The same applies to the smoothing capacitor C.

[0036] The semiconductor switches 13 and the semiconductor switches S1, S2 may be configured as a respective IGBT or MOSFET. The semiconductor switches S1, S2 particularly do not have to be contactors. The semiconductor switches 13, S1, S2 may be provided as semiconductor modules or, for short, submodules 17, as such may be arranged on a common semiconductor substrate, for example.

[0037] The series connection 14 sums the partial voltages 10 to form a DC voltage 18 that is provided in the DC link 3 between the positive conductor 15 and the negative conductor 16. The positive conductor 15 and the negative conductor 16 may each be provided by a wire or a bus bar, for example. To store electric power, the DC link 3 may have a battery B, for example an electrochemical storage battery having galvanic cells. The battery B does not have to perform voltage smoothing for the DC voltage 18, since the rectifiers 7 have dedicated smoothing capacitors C. The DC link 3 may furthermore have inductors L provided in it, for example electric coils.

[0038] The drive motor 6 may likewise have two separate motor coil systems M1, M2. The motor coil systems M1, M2 are each a polyphase coil arrangement. The motor coil systems M1, M2 may also be provided in different drive motors.

[0039] In the example shown in FIG. 1, the inverter arrangement 4 has two inverters 19, each of which is interconnected with another of the motor coil systems M1, M2 via respective AC voltage lines 20. The inverters 19 may be of the same design as the rectifiers 7. The inverters 19 can be operated as pulse-controlled inverters. To this end, they have half-bridges 9 with semiconductor switches 13. Only some of the semiconductor switches 13 of the inverters 9 are provided with a reference symbol for the sake of clarity. Each inverter 19 can have a smoothing capacitor C.

[0040] The inverters 19 are interconnected with the DC link 13 via a respective DC voltage connection 11, connection contacts 12 of the DC voltage connections 11 being interconnected to form a series connection 21. The connection contacts 12 of the inverters 19 have a respective partial voltage 24 of the DC voltage 18 dropped between them.

[0041] The DC voltage connections 11 of the inverters 19 can have a respective semiconductor switch S1 that forms a shorting circuit for the connection contacts 12. Furthermore, a semiconductor switch S2 may be provided that provides a decoupling circuit that can bring about a flow of current between one of the connection contacts 12 and the half-bridges 13 and/or the smoothing capacitor C by virtue of the semiconductor switch S2 being closed. To this end, the connection contact 12 and the half-bridges 13 and/or the smoothing capacitor C are interconnected via the semiconductor switch S2.

[0042] The smoothing capacitors C are each a local DC link capacitor.

[0043] The converter 1 can have a control device 22 that can switch semiconductor switches 13, S1, S2, so that they change between an electrically conductive state and an electrically inhibiting state. The semiconductor switches 13, S1, S2 of the inverters 19 may be provided in a respective inverter 19 by a submodule 23 that may be formed, by way of example on the basis of a common semiconductor substrate. The control device 22 may be formed, by way of example, on the basis of a microprocessor or microcontroller. The control device 22 may be distributed at least in part over the half-bridges 19. By way of example, they can comprise driver circuits of the semiconductor switches 13 of the half-bridges 9.

[0044] The series connection 14 connects the rectifiers 7 in series. The active rectifiers 7 are used to charge the smoothing capacitors C. The partial voltage 10 of a smoothing capacitor C can be adjusted by means of the generator windings of the generator coil systems G1, G2 and appropriate clocking of the active rectifiers 7. The switches S1, S2 can be used to connect the rectifiers 7 in parallel with the battery. This allows the battery to be charged. In this case, the following switching combinations arise:

[0045] In the case of each inverter 7, by opening S1 and closing S2, the respective generator coil system G1 or G2 can be connected to the battery B. By closing S1 and opening S2, the respective generator coil system G1, G2 can be isolated from the battery B. The partial voltages 10 in the rectifiers 7 may be greater in total than the battery voltage of the battery B. Without step-down converter mode, however, they must correspond in total to at least the battery voltage. Should both rectifiers 7 be in operation, then the partial voltage 10 of the two rectifiers is preferably of the same magnitude.

[0046] In the case of the inverters 19 too, multiple switching options arise on the basis of the semiconductor switches S1, S2 of the DC voltage connections 11 of the inverters 19. The motor coil systems M1, M2 are driven by means of a respective one of the inverters 19. Each inverter 19 is a pulse-controlled inverter in this case. The semiconductor switches S1, S2 can be used to connect the inverters 19 to the battery B or to isolate them therefrom. The battery voltage corresponds to the DC voltage 18.

[0047] The partial voltages 24 of the smoothing capacitors C in the inverters 19 may be greater in total than the battery voltage. They must correspond in total to at least the battery voltage, however, if there is no provision for a step-up converter during operation.

[0048] Should both inverters 19 be in operation, then the respective partial voltage 24 of the two inverters is preferably of the same magnitude.

[0049] The switching options described result in the following methods of operation of the converter that are able to be selected by the control device 22, for example.

[0050] In one method of operation, operation of only one rectifier 7 and of only one inverter 19 is possible. The other rectifiers 7 and inverters 19 are isolated from the circuits by closure of the semiconductor switches S1. This results in a cold redundancy in the converter 1. That is to say that in the event of a fault, the switch S1 is opened and S2 is closed, which charges the hitherto unprovisioned smoothing capacitors C. In other words, the remaining rectifiers or inverters are connected to the series connection 14, 21.

[0051] A further method of operation involves all rectifiers 7 and all inverters 19 being connected to the circuit, that is to say to the respective series connection 14, 21 (hot redundancy), via open semiconductor switches S1 and closed semiconductor switches S2.

[0052] Between cold redundancy and hot redundancy, there are also intermediate forms possible when there are more than two rectifiers/inverters.

[0053] A further method of operation involves all rectifiers 7 and all inverters 19 being in operation, with clocking of the semiconductor switches S1, S2 being performed. All rectifiers and inverters are connected to the circuit via respective open semiconductor switches S1 and closed semiconductor switches S2 with alternate clocking of S1 and S2 in a step-up converter mode or a step-down converter mode. The individual rectifiers 7 are preferably clocked in staggered fashion in their half-bridges 9 in order to reduce a current ripple in the inductors L.

[0054] In the event of a fault in one of the rectifiers 7 or inverters 19, it is possible for the control device, for example, to perform the following method. In the event of a fault in a rectifier or an inverter, the semiconductor switch S1 thereof can be closed, as a result of which the faulty circuit portion is isolated from the supply circuit, i.e. the DC link 3. Furthermore, in the event of a faulty inverter 19, discharge of the smoothing capacitor C can be followed by the semiconductor switches 13 of the half-bridges 9 being opened. The supply circuit is not interrupted during their method for the other rectifiers and inverters.

[0055] As an alternative to the semiconductor switch S1, it is also possible for the semiconductor switch S2 together with a half-bridge 9 of an inverter 19 to short this inverter on the input side, i.e. to short the connection contacts 12. The closed half-bridge 9 is then the shorting circuit for this inverter.

[0056] Further switching elements can provide additional protection in the event of a fault. In this regard, FIG. 2 shows a solution to the problem that the diodes (not represented in FIG. 2) connected in parallel besides an IGBT mean that, in the event of a permanent short in an IGBT, the directly connected winding of a motor coil system is shorted. This gives rise to losses in the drive motor. The same applies to a generator. FIG. 2 shows the solution only for an inverter 19. This can also take place analogously in the case of a rectifier 7.

[0057] If the permanent short via one of the semiconductor switches 13 is undesirable, then the motor coil system M1 can be isolated from the inverter 19 or active rectifier 7 by means of two additional semiconductor switches S3 per inverter or rectifier by switching at the current zero crossing. The additional semiconductor switches S3 are closed during operation of the converter 1 (called normally on). The semiconductor switches S3 are used to prevent a shorted winding in the event of a fault in one of the half bridges 9 when one of the semiconductor switches 13 is continuously in the electrically conductive state.

[0058] The converter 1 has the overall result of a circuit topology for a modular high-frequency converter for meeting redundancy demands in an electrically driven aircraft. It is possible to use submodules 17, 23 of the same design for connecting the generator and the motor to the battery B. FIG. 1 shows how dual redundancy can be provided without contactors.

[0059] In this regard, FIG. 3 shows how the topology can be extended to any desired number of submodules by virtue of the rectifier arrangement 2 and the inverter arrangement 4 having a total of N rectifiers 7 and N inverters 19. In this case, N is an integer greater than 1.

[0060] FIG. 4 illustrates how, by modifying the converter 1, the rectifiers 7 can be reduced to a respective passive rectifier for which, instead of the semiconductor switches 13 in the half bridges 9, diodes 25 are provided. For the sake of clarity, only some diodes 25 are provided with a reference symbol in FIG. 4. In this case, the half bridges 9 themselves are each a shorting circuit for bypassing the respective generator coil systems G1, G2, GN. The generator coil systems G1, G2, GN may in this case each, as illustrated in FIG. 2, be interconnected with the diode rectifiers via switches S3.

[0061] FIG. 5 illustrates how the converter 1 may be provided by way of example in an aircraft 26. FIG. 4 shows a fixed-wing aircraft 26 in which a propeller 27 can be driven by the drive motor 6. The propeller 27 is rotated about a shaft 28 by the drive motor 6. In the example, the drive motor 6 is an electric machine that is operated in motor mode. The power for driving the propeller 27 can be obtained by virtue of an internal combustion engine 29, which may be a gasoline engine or a diesel engine or a turbine, for example. The internal combustion engine 29 can use a shaft 30 to drive the generator 5. The electric generator provided may be an electric machine in generator mode. A speed of the shaft 30 is independent of a speed of the shaft 28 in this case. In this regard, the AC voltage produced by the generator 5 is converted by means of the converter 1, in the manner described, into AC voltage that can be supplied to the drive motor 6 via the AC voltage phase conductors 9. A switching frequency for the inverters 7 is selected by the control device 22 on the basis of a rated speed of the propeller 27 in this case. The rated speed can in this case be selected or prescribed by a pilot, for example, by means of an operating element (not shown).

[0062] Overall, the example shows how the invention can provide a redundant circuit topology for an ePlane converter without contactors.