Power electronics system for operating an electric machine, electric drive unit, and method for operating an electric power electronics system

Abstract

The invention relates to a power electronics system (1) for operating an electric machine, having at least one half-bridge (3) that is assignable or assigned to a phase (2) of a drive winding of the electric machine, wherein the half-bridge (3) has at least one actuatable first semiconductor switch (4), and at least one gate driver (6) is connected upstream of the first semiconductor switch (4) for the purposes of actuating same. Provision is made for at least two gate drivers (6) connected electrically in parallel to be connected upstream of the first semiconductor switch (4), and for the gate drivers (6) to each be designed to apply a specifiable electrical current to the first semiconductor switch (4) for the purposes of actuating same.

Description

[0001] Description

[0002] title

[0003] Power electronics for operating an electrical machine, electrical

[0004] Drive unit, method for operating electrical power electronics

[0005] The invention relates to a power electronics system for operating an electrical machine, comprising at least one half-bridge which is or can be assigned to a phase of a drive winding of the electrical machine, wherein the half-bridge has at least one controllable first semiconductor switch, and wherein at least one gate driver is connected upstream of the first semiconductor switch for controlling it.

[0006] Furthermore, the invention relates to an electric drive unit with such power electronics and a method for operating such power electronics.

[0007] State of the art

[0008] Power electronics of the type mentioned above are known from the state of the art. A key development issue for such power electronics is their availability and robustness against malfunctions, especially in automotive applications such as highly automated or autonomous driving. In particular, the failure of vehicle components such as brakes and steering must be reliably prevented. If the brakes and / or steering are designed as by-wire systems, a control signal is transmitted exclusively via electronic signals; there is no mechanical override as a fallback. It is therefore known to provide appropriate redundancies for the electrical components, for example, multiple electrical machines and / or power electronics.For example, the published patent application DE 102014 203 568 A1 discloses an electric drive system with an electric machine having at least two three-phase winding phases, each of the winding phases being assigned its own inverter, and each of the inverters being assigned its own DC voltage source. Such modularization is intended to create a redundant system in which, in the event of a failure of a single DC voltage source, an emergency operation function with limited performance can be set up by deactivating the defective or faulty part and supplying the electric machine with reduced power from the remaining inverter parts.

[0009] German Patent Application DE 102014 113 542 A1 discloses an electric drive system with at least one multi-phase electric machine having at least two redundant phase winding strands for at least one phase, and with a circuit device with separate electrical circuit units for supplying the phase winding strands with electricity. At least one of the circuit units is configured to supply electricity to at least two of the phase winding strands whose associated phases are different from one another. In particular, at least one of the circuit units has an independent electrical supply, so that in the event of a fault, at least the remaining functional modules can be used to continue operating the electric machine.

[0010] Disclosure of the invention

[0011] The power electronics according to the invention with the features of claim 1 is characterized in that at least two gate drivers connected electrically in parallel are connected upstream of the first semiconductor switch, and in that the gate drivers are each designed to apply a predeterminable electrical current to the first semiconductor switch for its control. An important difference from the power electronics systems mentioned above lies in the fact that the gate drivers are not designed, as is usual, to apply an electrical voltage to the respective semiconductor switch, but rather an electrical current. The invention is based on the finding that the area most at risk of failure is not the electrical machine, but the power supply of the power electronics.Thus, the power electronics described at the outset relate to significantly more complex circuits than those proposed by the invention, wherein the circuit in particular requires at least a six-phase machine or wherein at least one of the half-bridges with the semiconductor switches must be designed redundantly for the arrangement to function as desired. Because the power electronics according to the invention are current-controlled in this respect, a switching or disconnecting device between gate drivers is advantageously dispensed with, so that the power electronics has a reduced number of components and is therefore more cost-effective. When two redundantly designed, voltage-controlled gate drivers are connected in parallel, such a device would be mandatory because they would otherwise block each other. The correspondingly high outlay for switching and / or disconnecting is advantageously eliminated with the power electronics according to the invention.Redundancy is achieved simply by doubling the gate driver as an upstream module, without the need for additional components.

[0012] According to a preferred embodiment of the invention, the gate drivers each have a high-impedance current source or are connected to one. This makes the advantages of the power electronics according to the invention particularly pronounced. In contrast to the previously mentioned known power electronics, no low-impedance voltage sources are used.

[0013] Particularly preferably, the power electronics system comprises a control device configured to control the gate drivers to supply current to the first semiconductor switch selectively or in parallel during normal operation. This provides the advantage that the power supply to the semiconductor switch is always secure.

[0014] According to a preferred development of the invention, the power electronics comprises a control device configured to deactivate the affected gate driver upon the occurrence of a malfunction. This advantageously ensures that, even if one of the power supplies provided by the gate drivers fails, the semiconductor switch is reliably supplied with power by the still functioning gate driver, without the control being affected by the failed or defective gate driver.

[0015] Particularly preferably, the half-bridge comprises at least one second controllable semiconductor switch, upstream of which at least two further gate drivers connected electrically in parallel are connected. The gate drivers are each configured to supply the second semiconductor switch with a predeterminable electrical current for its control. This provides the advantage that each of the semiconductor switches has advantageous redundancy in its power supply.

[0016] According to a preferred embodiment of the invention, the first semiconductor switch is designed as a high-side switch, and the second semiconductor switch is designed as a low-side switch. With such a design, the advantages of the power electronics according to the invention are particularly pronounced.

[0017] The electric drive unit with the features of claim 7 comprises an electric motor and is characterized by the power electronics according to the invention. This results in the aforementioned advantages.

[0018] Particularly preferably, the electrical machine has three electrical phases, and the power electronics has such a half-bridge for each of the electrical phases. This creates a particularly advantageous redundancy in the power supply for each of the electrical phases.

[0019] The method for operating the power electronics according to the invention with the features of claim 9 is characterized in that, during normal operation, the gate drivers are controlled to supply the semiconductor switch with a predetermined electrical current, either selectively or in parallel. This creates a particularly advantageous application for the power electronics, which always ensures that the semiconductor switch is reliably supplied with electrical current.

[0020] According to a preferred embodiment of the invention, the gate drivers are monitored for malfunctions, and if a malfunction of one of the gate drivers is detected, the respective gate driver is deactivated. This advantageously ensures that even if one of the power supplies provided by the gate drivers fails, the semiconductor switch is reliably supplied with power by the still functioning gate driver, without the control being affected by the failed or defective gate driver.

[0021] Further preferred features and combinations of features emerge from the above description and from the claims. The invention is explained in more detail below with reference to the drawings.

[0022] Figure 1 shows a partial circuit diagram of an advantageous power electronics, and

[0023] Figure 2 shows a method for operating the power electronics.

[0024] Figure 1 shows a partial circuit diagram of a power electronics system 1 for operating a phase 2 of a drive winding of an electrical machine not otherwise shown in detail. The power electronics system 1 has a half-bridge 3 assigned to phase 2. Preferably, the power electronics system 1 has such a half-bridge 3 for each of the phases.

[0025] The half-bridge 3 has a controllable first semiconductor switch 4, which is embodied here as a high-side switch HS. Furthermore, the half-bridge 3 has a controllable second semiconductor switch 5, which is embodied here as a low-side switch LS.

[0026] Two first gate drivers 6, electrically connected in parallel, are connected upstream of the first semiconductor switch 4 for its control. The first gate drivers 6 are each designed to apply a predeterminable or predetermined electrical current to the first semiconductor switch 4 for its control.

[0027] Two second gate drivers 7, electrically connected in parallel, are connected upstream of the second semiconductor switch 5 for its control. The second gate drivers 7 are each designed to apply a predeterminable or predetermined electrical current to the second semiconductor switch 5 for its control.

[0028] The gate drivers 6, 7 each have a high-impedance current source or are connected to a high-impedance current source. A control device 8 is assigned to the gate drivers 6, 7, which is configured to control the gate drivers 6, 7 to supply current to the respective semiconductor switches 4, 5 selectively or in parallel during normal operation, and to deactivate the affected gate driver if a malfunction occurs. Finally, a supply 9 is assigned to the half-bridge 3.

[0029] An advantageous method for operating the power electronics 1 is described below with reference to Figure 2. Figure 2 illustrates the method using a flowchart. In particular, the method ensures that the semiconductor switches 4, 5 are always reliably supplied with power to operate the electrical machine.

[0030] In a step S1, the method begins with the gate drivers 6, 7 being controlled by the control device 8 during normal operation to apply a predetermined electrical current to the respective semiconductor switches 4, 5 in parallel, in particular alternately. Alternatively, only one of the gate drivers 6, 7 is controlled by the control device 8 to selectively apply the predetermined electrical current to the respective semiconductor switches 4, 5.

[0031] In parallel, the gate drivers 6, 7 are monitored for malfunctions. If a malfunction of one of the gate drivers 6, 7 is detected, the method continues with step S2. In step S2, the respective gate driver 6, 7 is deactivated by the control device 8 to ensure that its defect does not affect the functioning of the power electronics 1. Control of the still functional gate driver 6, 7 continues normally.

[0032] As soon as it is detected that the faulty or defective gate driver 6, 7 is functional again, it is reactivated by the control device 8. The

[0033] The method then ends with a step S3.

Claims

Claims 1 . Power electronics (1) for operating an electrical machine, - with at least one half-bridge (3) which can be assigned or is assigned to a phase (2) of a drive winding of the electrical machine, - wherein the half-bridge (3) has at least one controllable first semiconductor switch (4), and - wherein the first semiconductor switch (4) is provided with at least one Gate driver (6) is connected upstream, characterized in that at least two gate drivers (6) connected electrically in parallel are connected upstream of the first semiconductor switch (4), and in that the gate drivers (6) are each designed to apply a predeterminable electrical current to the first semiconductor switch (4) in order to control it.

2. Power electronics according to claim 1, characterized in that the gate drivers (6) each have a high-impedance current source or are connected to such a source.

3. Power electronics according to one of the preceding claims, characterized by a control device (8) which is designed to control the gate drivers (6) in each case to supply the first semiconductor switch (4) with current selectively or in parallel during normal operation.

4. Power electronics according to one of the preceding claims, characterized by a control device (8) which is designed to deactivate the affected gate driver (6) when a malfunction occurs.

5. Power electronics according to one of the preceding claims, characterized in that the half-bridge (3) has at least a second controllable semiconductor switch (5), upstream of which at least two further gate drivers (7) connected electrically in parallel are connected, wherein the gate drivers (7) are each designed to apply a predeterminable electrical current to the second semiconductor switch (5) for its control.

6. Power electronics according to claim 5, characterized in that the first semiconductor switch (4) is designed as a high-side switch and the second semiconductor switch (5) is designed as a low-side switch.

7. Electric drive unit, with an electric machine, characterized by power electronics (1) according to one of the preceding claims.

8. Drive unit according to claim 7, characterized in that the electrical machine has three electrical phases (2), and that the power electronics (1) has such a half-bridge (3) for each of the electrical phases (2).

9. Method for operating an electrical power electronics system (1) according to one of claims 1 to 6, characterized in that the gate drivers (6, 7) are controlled in normal operation to supply the semiconductor switch (4, 5) with a predetermined electrical current selectively or in parallel.

10. The method according to claim 9, characterized in that the gate drivers (6, 7) are monitored for malfunction, and that if a malfunction of one of the gate drivers (6, 7) is detected, the respective gate driver (6, 7) is deactivated.

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