switching element

Abstract

Switching element with a plurality of control terminals (253, 255), each of which is to be assigned to a control line, wherein the switching element is divided into a plurality of partitions (282, 284), and each partition (282, 284) is assigned to one of the control terminals (253, 255).

Description

[0001] The invention relates to a switching element for an arrangement for controlling an electric motor, such an arrangement and a method for controlling an electric motor. State of the art

[0002] To control electric motors, so-called power converters are used. These converters are used to convert one type of current, i.e., direct current or alternating current, into the other type, or to change characteristic parameters of the current, such as amplitude or frequency. A distinction is made between rectifiers, inverters, and converters.

[0003] Multiphase electric motors are often controlled by inverters, which convert the supplied direct current into single-phase or multiphase alternating current. Such an inverter is also referred to as an inverter or power amplifier, which is used to control the electric motor.

[0004] Electric motors are used in a variety of applications in motor vehicles. Typical applications include electric steering or power steering systems or electronic stability control (ESP). It should be noted that these are safety-critical applications.

[0005] Furthermore, it should be noted that with the increasing electrification of vehicle components, the need for redundant control systems is steadily increasing in order to meet the requirements of fault-tolerant circuits. This is particularly relevant for the aforementioned vehicle functions, namely electric steering and ESP, as these functions have a high ASIL (Automotive Safety Integrity Level) rating. The need for fault-tolerant circuits is also increasing with their use in autonomous vehicles.

[0006] Current solutions, for example, use redundant B6 bridges and 2x3-phase motors. These two subsystems are controlled via redundant electronic components and synchronized by exchanging a clock signal. However, this creates additional complexity in the drive system due to a complex electric motor. For this purpose, Fig. 1.

[0007] DE 10 2017 212 595 A1 discloses an inverter for an electrical machine.

[0008] DE 10 2017 223 631 A1 also shows an inverter for an electrical machine.

[0009] DE 11 2017 001 344 T5 discloses an engine control device.

[0010] EP 3 021 480 A1 shows an electric motor with a power module. Disclosure of the invention

[0011] Against this background, a switching element having the features of claim 1, an arrangement according to claim 5 and a method according to claim 8 are presented. Embodiments emerge from the dependent claims and from the description.

[0012] The switching element presented, in particular an electrical switching element, has a plurality of control terminals, each of which is assigned to a control line. The control lines are, in turn, assigned to a control path. Furthermore, the switching element is divided into a plurality of partitions, each partition being assigned to one of the control terminals.

[0013] Furthermore, an output stage is described which is designed to generate a phase current for driving an electric motor, wherein the output stage has a number of switching elements, typically a plurality of switching elements, which are each to be controlled via a switching signal, wherein the switching elements each have a plurality of control connections which in turn are each to be assigned to a driver unit.

[0014] Electronic switches, typically MOSFETs, are often used as switching elements, and these are widely available in various designs. In this case, the gate terminals of the MOSFET are the control terminals.

[0015] The presented arrangement is used to control an electric motor and has an output stage of the type described here as well as several control paths. A driver unit is provided in each control path, with which a switching signal for switching a switching element is to be generated. The driver units are assigned to the switching elements in such a way that each switching element can be selectively switched by several driver units from different control paths.

[0016] In one embodiment, two control paths and thus two driver units are provided. The switching elements then have two control connections and can be selectively controlled for switching by both driver units from the two control paths.

[0017] The described method is used to control an electric motor and is implemented using an arrangement of the type described herein. This arrangement comprises a plurality of control paths, each of which contains a driver unit, and an output stage with a plurality of switching elements, each switching element being selectively switched via switching signals from a plurality of driver units from different control paths.

[0018] The control pins can be looped from one driver unit through another. Furthermore, the control pins can be synchronized using a common clock signal.

[0019] MOSFETs are typically used as switching elements. Furthermore, two control paths are usually provided. The MOSFETs each have two control terminals, which can be addressed by both driver units from the two control paths, so that they switch to generate the control signal.

[0020] The described power stage represents a redundant power stage for an electric motor, whereby the complexity is neither significantly increased nor does it merely represent a duplication of a known power stage.

[0021] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0022] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention. Short description of the drawings Fig. 1 shows a block diagram of a redundant control of a 2x3 phase electric motor according to the state of the art. Fig. Figure 2 shows a configuration with a redundant power stage for controlling an electric motor on one phase as an example. Fig. Figure 3 shows a configuration of a control of a three-phase electric motor with a B6 bridge according to the state of the art. Fig. 4 shows a MOSFET according to the invention with two gate control lines and a circuit with two gate drivers. Fig. 5 shows a redundant control path up to a six-phase electric motor. Fig. 6 shows the overall structure of an output stage using a MOSFET of the type described herein with two gate terminals according to an embodiment of the presented method. Fig. 7 shows the overall structure of an output stage using a MOSFET of the type described herein with two gate terminals and synchronization via a common clock signal according to an embodiment of the presented method. Fig. Figure 8 shows a schematic representation of an arrangement for controlling an electric motor. Embodiments of the invention

[0023] The invention is illustrated schematically in the drawings using embodiments and is described in detail below with reference to the drawings.

[0024] Fig. Figure 1 shows a block diagram of an arrangement 10 for redundantly controlling a 2x3-phase electric motor 12 according to the prior art. Two paths, namely a first path 20 and a second path 40, are provided for this redundant control. The first path 20 includes a first monitoring module 22, implemented in an ASIC, a first microcontroller 24, a first gate driver unit 26 (GDU), and a first output stage 28, which includes, for example, two MOSFETs. Also shown are a positive battery terminal B+ 30, a negative battery terminal B- 32, and a first measuring device 34 for detecting a phase current I phase and a second measuring device 36 for detecting the rotor position. The outputs of the first output stage 28 are the phase lines U 38, V 40, and W 42. Each of the phase lines 38, 40, and 42 is assigned a measuring device 34. The measuring device 36 is required only once within the phase package 38, 40, and 42.

[0025] In the second path 50, a second monitoring module 52, implemented in an ASIC, a second microcontroller 54, a second gate driver unit 56, and a second output stage 58, which comprises two MOSFETs, are provided. Also shown are a positive battery terminal B+ 60, a negative battery terminal B- 62, where the battery terminal 60 can be identical to the battery terminal 30 and the battery terminal 62 can be identical to the battery terminal 32, and a first measuring device 64 for detecting a phase current I phaseand a second measuring device 66 for detecting a rotor position. The outputs of the second output stage 58 are the phase lines U 68, V 70, and W 72. Each of the phase lines 68, 70, and 72 is assigned a measuring device 64. The measuring device 66 is required only once within the phase packet 68, 70, and 72. Synchronization 80 between the two paths 20 and 50 takes place between the two microcontrollers 24 and 54.

[0026] Thus, two completely separate paths 20 and 50, each with its own output stage 28 and 58, are provided for redundantly controlling the electric motor 12. This type of redundancy is thus implemented at the level of the phase packets in the motor and is known from the prior art.

[0027] Fig. Figure 2 shows a possible configuration in which the control path is doubled up to the output stage. However, the motor itself is only three-phase. The illustration shows an arrangement 100 for controlling an electric motor 102, which has a first control path 110 and a second control path 130. A first monitoring component (ASIC) 112, a first microcontroller 114, a first gate driver unit 116, and a first output stage 118 are provided in the first control path 110. A second monitoring component (ASIC) 132, a second microcontroller 134, a second gate driver unit 136, and a second output stage 138 are provided in the second control path 130. A rotor position 140 and three phase currents 142 are monitored. Furthermore, the diagram shows a switch 150, with which one of the two control paths 110 or 130 can be activated. For further clarity, another path 160 is shown, which reflects the degree of realism.This further path 160 comprises a first symbol 162 for the monitoring module and microcontroller, a second symbol 164 for the gate driver, characterized by the gate voltage V. Gate , a third symbol 166 for the final stage, characterized by the phase current I Phase , and a fourth symbol 168 for the electric motor.

[0028] It is therefore clear that in this solution, the switch 150 is required to activate one of the two control paths or branches 110 or 130. Not shown is a control electronics that controls the switch 150 depending on the state of the control paths 110, 130. It is obvious that this solution represents a significant additional effort compared to a conventional configuration, as used, for example, in Fig. 3 is shown.

[0029] Fig. Figure 3 shows a conventional configuration of a machine control system with a B6 bridge. The illustration shows a microcontroller 200, a first gate driver unit 202 with associated output stage 204, a second gate driver unit 206 with associated output stage 208, a third gate driver unit 210 with associated output stage 212, and an electric motor 214. The illustration also shows a first line 220 for connection to the positive battery terminal B+ and a second line 222 for connection to the negative battery terminal B-.

[0030] It will be repeated again Fig. 2. It should be noted that it is not certain whether the configuration according to Fig. 2 brings a real gain in availability, since the control electronics for the switch also have to be monitored or duplicated, thus making the circuit even more complex.

[0031] Fig. Figure 2 illustrates the degree of reality of a control path below with the additional path 160. In the microcontroller, the control path is purely virtual, operating at the level of numbers, or rather, bits and bytes. After the driver, these become gate control signals. After the respective half-bridge, these become phase currents, and after the motor, torque. It can be seen that redundancy is relatively easy to achieve in the virtual realm, for example, by two computers operating in parallel. In the figure, duplication becomes increasingly complex toward the right, and at some point, the two control paths 110 and 130 must be merged into one control path.

[0032] The present invention provides a low-cost approach to this end.

[0033] Fig. Figure 4 shows a MOSFET 250 with two gate drive lines 252 and 254 and two associated control terminals 253, 255, each of which is assigned its own gate driver, in this case a first gate driver 260 and a second gate driver 262, respectively. The first gate driver 260 is assigned to the first control terminal 253 and the first gate drive line 252. The second gate driver 262 is assigned to the second control terminal 255 and the second gate drive line 254. The gate drive lines 252, 254 represent drive lines as recited in the claims. The illustration also shows a drain terminal 270 and a source terminal 272.

[0034] The MOSFET 250 represents an electronic switch with the classic connections Gate, Drain 270 and Source 272, where the Gate is the connection for controlling the MOSFET 250. Modern FETs, especially so-called Trench FETs, are constructed in such a way that an FET is composed of several small parcels or partitions that are then connected in parallel. This is Fig. 4 by a checkerboard pattern 280, which illustrates the two partitions, namely a first partition 282 and a second partition 284, of the MOSFET 250. The partition 282 consists of Fig. 4 consists of the second, fourth, sixth, and eighth strips. All of these lines are electrically connected to each other on the surface of MOSFET 250. Partition 284 consists of the first, third, fifth, and seventh strips. These are also connected to each other on MOSFET 250.

[0035] The gate is thus provided not only with one control terminal, but also with a zebra-striped pattern, e.g., dividing the MOSFET into two parts. Thus, two control terminals 253, 255 are provided.

[0036] This creates two paths, each electrically activating half of the MOSFET 250, but thermally providing the full heat dissipation path due to the very high thermal conductivity within the silicon. This creates two independent control paths up to the output stage, with slightly reduced performance compared to a single-control output stage. It is obvious that if one of the two paths fails, the other can perform the control.

[0037] It is further proposed as an embodiment that in the 'normal state' the control signal for the second gate region. - either directly from the second driver - or loop through the second driver.

[0038] In the second case (looping through), a simple temporal synchronization is achieved.

[0039] Fig. Figure 5 shows a redundant drive path comprising a first drive path 300 and a second drive path 302, leading to an electric motor 304 configured as a 6-phase machine. Here, a set of three phase connections is supplied from a first driver unit 306, while the other set is supplied from a second driver unit 308. This allows the redundancy of the drive path to be further expanded toward torque generation.

[0040] Fig. Figure 6 shows the overall design of a control system for an electric motor using the presented MOSFET. The circuit is shown for only one phase as an example.

[0041] The illustration shows an arrangement 400 for controlling an electric motor 402, which includes a first control path 410 and a second control path 430. A first monitoring component (ASIC) 412, a first microcontroller 414, and a first gate driver unit 416 are provided in the first control path 410. A second monitoring component (ASIC) 432, a second microcontroller 434, and a second gate driver unit 436 are provided in the second control path 430.

[0042] A first MOSFET 418 and a second MOSFET 438 form an output stage 439. A rotor position 440 and a phase current 442 are monitored.

[0043] For further clarification, another path 460 is shown, reflecting the degree of realism. This additional path 460 includes a first symbol 462 for the monitoring module and microcontroller, a second symbol 464 for the gate driver unit, characterized by the gate voltage V Gate, a third symbol 466 for the MOSFET or the output stage comprising the MOSFET, characterized by the phase current I Phase , and a fourth symbol 468 for the electric motor.

[0044] The two MOSFETs 418 and 438, which form the output stage 439, each have two gate terminals, whereby these two terminals are each to be controlled by one of the two gate driver units 416 and 436, which can communicate with each other (connection 470). Both gate driver units 416, 436 can thus access both MOSFETs 418, 438. A double arrow 472 in the second gate driver unit 436 illustrates the possibility of switching. Thus, according to the invention, the control path 410 has the possibility of replacing the function of the control path 430 in the event of a defect in the control path 430 and vice versa. According to the invention, a fault-redundant system for the control path is therefore created.

[0045] Fig. 7 shows an alternative solution. Here, the presented MOSFET is installed and the synchronization, similar to Fig. 1, via a clock signal at the microcontroller level.

[0046] The illustration shows an arrangement 500 for controlling an electric motor 502, which has a first control path 510 and a second control path 530. A first monitoring component (ASIC) 512, a first microcontroller 514, and a first gate driver unit 516 are provided in the first control path 510. A second monitoring component (ASIC) 532, a second microcontroller 534, and a second gate driver unit 536 are provided in the second control path 530.

[0047] A first MOSFET 518 and a second MOSFET 538 form the output stage 539. A rotor position 440 and a phase current 442 are monitored.

[0048] For further clarification, another path 560 is shown, reflecting the degree of realism. This additional path 560 includes a first symbol 562 for the monitoring module and microcontroller, a second symbol 564 for the gate driver, characterized by the gate voltage V Gate , a third symbol 566 for the MOSFET or the output stage comprising the MOSFET, characterized by the phase current I Phase , and a fourth symbol 568 for the electric motor.

[0049] The two MOSFETs 518 and 538, which form the output stage 539, each have two gate terminals, each of which can be controlled by one of the two gate driver units 516 and 536. Both gate driver units 516 and 536 can thus access both MOSFETs 518 and 538. A dashed double arrow 570 indicates synchronization via a clock signal.

[0050] Fig.8 shows a purely schematic representation of an arrangement 600 for controlling an electric motor 602. The illustration shows a first control path 610 and a second control path 620. A first microcontroller 612 and a first gate driver unit 614 are provided in the first control path 610. A second microcontroller 622 and a second gate driver unit 624 are provided in the second control path 620. Furthermore, the arrangement 600 comprises an output stage 630 in which switching elements, e.g., MOSFETs, of the type described herein are provided. These switching elements are characterized in that they can be selectively controlled via the two control paths 610, 620. This means that there is redundant availability of control paths 610, 620 for controlling the output stage 630. This is illustrated in this purely schematic representation by an element 640. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2017 212 595 A1

[0007] DE 10 2017 223 631 A1

[0008] DE 11 2017 001 344 T5

[0009] EP 3 021 480 A1

[0010]

Claims

[1] Switching element with a plurality of control terminals (253, 255), each of which is to be assigned to a control line, wherein the switching element is divided into several partitions (282, 284), and each partition (282, 284) is assigned to one of the control ports (253, 255). [2] Switching element according to claim 1, wherein the control lines are assigned to a control path (300, 302, 410, 430, 510, 530, 610, 620). [3] Switching elements according to claim 1 or 2, which is designed as a MOSFET (250, 418, 438, 518, 538) which has a plurality of control terminals (253, 255) at the gate and is divided into a corresponding number of partitions (282, 284) in the number of control terminals (253, 255), wherein the partitions (282, 284) are each to be electrically activated via the associated control terminals (253, 255). [4] Switching element according to claim 3, wherein the MOSFET (250, 418, 438, 518, 538) is divided into equally sized partitions (282, 284). [5] Arrangement for controlling an electric motor (304, 402, 502, 602) with an output stage (439, 539, 630) and several control paths (300, 302, 410, 430, 510, 530, 610, 620), wherein - a number of switching elements according to one of claims 1 to 4 are provided in the output stage (439, 539, 630); - in each control path (300, 302, 410, 430, 510, 530, 610, 620) a driver unit (306, 308) is provided, with which a switching signal for switching a switching element is to be generated, - the driver units (306, 308) are assigned to the switching elements in such a way that each switching element can be selectively switched by several driver units (306, 308) from different control paths (300, 302, 410, 430, 510, 530, 610, 620) via the assigned control connections. [6] Arrangement according to claim 5, wherein the output stage (439, 539, 630) is designed as a B6 bridge. [7] Arrangement according to claim 5 or 6, wherein in each control path (300, 302, 410, 430, 510, 530, 610, 620) a microcontroller (414, 434, 514, 534, 611, 612) and a monitoring module (412, 432, 512, 532) are further provided, which are connected upstream of the driver unit (306, 308). [8] Method for controlling an electric motor (304, 402, 502, 602) with an arrangement (400, 500, 600) according to one of claims 5 to 7, wherein the arrangement (400, 500, 600) has a plurality of control paths, in each of which a driver unit (306, 308) is provided, and an output stage (439, 539, 630) with a number of switching elements, wherein each switching element is selectively switched via switching signals from a plurality of driver units (306, 308) from different control paths (300, 302, 410, 430, 510, 530, 610, 620). [9] Method according to claim 8, in which switching signals are looped through driver units (306, 308) from different control paths (300, 302, 410, 430, 510, 530, 610, 620). [10] Method according to claim 8 or 9, wherein the control paths (300, 302, 410, 430, 510, 530, 610, 620) are synchronized via a common clock signal.

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