Communication system for electric vehicles

Abstract

System (100) for controlling an electric machine in a motor vehicle, the system comprising a plurality of submodules (110), each submodule (110) being configured for power transmission to or from a part of the electric machine and having an interface (118, 119) for data communication, a first data communication structure and a second data communication structure, wherein both the first and the second data communication structure are connected to the interfaces of the plurality of submodules (110) in such a way that they each form a closed ring, and wherein the system (100) further comprises a central control unit (140) which is connected to the interfaces of two submodules (110).

Description

The present invention relates in particular to the technical field of motor vehicles and specifically to a system for controlling an electric machine in a motor vehicle with an electric drive. In the automotive sector, availability is a crucial system characteristic of the vehicle. With conventional electric drives, the control and regulation are centrally connected to the power section of the inverter via a control and communication unit (control board). A failure of this control structure inevitably leads to a system failure of the drive unit and thus renders the vehicle undrivable. Due to the design of multilevel converters, so-called submodules (power units with control circuitry, logic unit, and data acquisition) are connected to the higher-level control unit via a star-shaped communication interface. This star-shaped arrangement makes it possible to address each individual submodule directly from the control unit. A short circuit in one of the data lines of a star topology can lead to the failure of the entire system (damage to the higher-level control unit). However, usually only the affected submodule fails. In either case, the vehicle is no longer drivable. Another disadvantage of the star-shaped structure is the indirect communication between the individual submodules. All relevant data from the individual modules must be read and written via the control board. The control of the input and output circuits (battery and motor) takes place exclusively on the control board (master). Other data network topologies also exist, such as: The publication DE 10 2011 081 720 A1 describes a converter circuit in a vehicle, wherein a control unit is connected to a vehicle communication network, which is designed as a CAN bus, for example. The publication DE 10 2012 210 057 A1 describes a ring data network that connects different components of a vehicle, such as an engine control unit, a brake control unit and an airbag control unit. Document WO 2014 / 089613 A1 shows a motor control in which one or more electronic components in the form of winding control units are connected via a communication bus designed as a "token ring", whereby in this version only the electronic components are provided in the ring. General ring data networks are known from the following two standards, for LANs (Local Area Networks) and MANs (Metropolitan Area Networks). The "stations" (general data sources and sinks) connected by the defined networks are shown without application or functional specifications. A token ring standard is described in “IEEE: Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 5: Token ring access method and physical layer specifications” - ANSI / IEEE Std 802.5, 1998 edition. In “IEEE: IEEE Standards for Local and Metropolitan Area Networks: Supplement to Token Ring Access Method and Physical Layer Specifications - Recommended Practice for Dual Ring Operation with Wrapback Reconfiguration” - IEEE Std 802.5c - September 18, 1991, an extension for a Token Ring structure is described for the implementation of a dual ring structure. The present invention is based on the objective of providing an improved data communication system for controlling an electric machine in a motor vehicle, which is more robust and efficient compared to known data structures for motor vehicle engine controls. This problem is solved by the subject matter of the independent claims. Advantageous embodiments of the present invention are described in the dependent claims. A system for controlling an electric machine is described. The described system comprises: (a) a plurality of submodules, each submodule being configured for power transmission to or from a part of the electric machine and having a data communication interface, (b) a first data communication structure, and (c) a second data communication structure, wherein both the first and the second data communication structure are connected to the interfaces of the plurality of submodules in such a way that they each form a closed loop. The electric machine is intended for use in a motor vehicle, for example as a traction motor or as a starter / generator. The electric machine can be configured as a motor and / or a generator. Each submodule is designed to supply power to a part (e.g., a phase) of the electric machine and / or to receive power from that part or phase. The described system is based on the understanding that a double-ring structure is formed by the first and second data communication structures, each forming a separate closed ring. Each closed ring enables direct data communication between the submodules, and should one of the closed rings be breached, for example due to a short circuit, the other closed ring remains intact and the submodules can continue to communicate with each other without restriction. A system is a device, in particular a circuit arrangement. For example, one of several phases or windings, or phase windings, is referred to as part of an electrical machine. The system has a first data communication structure with a first data communication line, the second data communication structure with a second data communication line, and the interfaces of the submodules are connected in parallel to the first and second data communication lines. In other words, the interface of each submodule is connected to both the first and second data communication lines. This means the submodules are arranged in parallel along the two data communication lines. Consequently, each submodule has direct access to data transmitted on both data communication lines and can also directly input its own data into both data communication lines so that it can be forwarded to other submodules. According to a further embodiment of the invention, the first data communication structure has a first plurality of data communication lines, which constitute a first serial connection between the interfaces of the submodules, and the second data communication structure has a second plurality of data communication lines, which constitute a second serial connection between the interfaces of the submodules. In this embodiment, the submodules are serially connected, or cascaded, by both the first and second data communication structures. The first data communication structure has a first plurality of data communication lines, each providing a first connection between the interfaces of two adjacent submodules, so that all submodules are connected by a first closed ring. Similarly, the second data communication structure has a second plurality of data communication lines, each providing a second connection between the interfaces of two adjacent submodules, so that all submodules are also connected by a second closed ring. In this case as well, all submodules can communicate directly with each other via the two ring-shaped data communication structures. In other words, each submodule can receive and use data from all other submodules and can transmit data to all other submodules. According to a further embodiment of the invention, the first and second data communication lines or the first and second plurality of data communication lines comprise electrical, optical or magnetic data communication lines. Electrical data communication lines are in particular electrical cables of conductor tracks with one or more signal lines, for example copper lines. Optical data communication lines are, in particular, optical waveguides or fibers suitable for transmitting optical signals. Magnetic data communication lines are, in particular, line structures suitable for data transmission using magnetic effects. The system also features a central control unit that is connected to the interfaces of two submodules. The central control unit is responsible for the overall control of the submodules and includes at least a processor, memory, and suitable interfaces. The central control unit may, for example, specify target values ​​for the individual submodules, start and stop the execution of certain functions or programs, etc. Furthermore, the central control unit may be responsible for monitoring the submodules in order to detect and, if necessary, correct errors. The central control unit is connected to the interfaces of two submodules. Should the connection to one of the two submodules fail, the central control unit can still communicate with the other submodule and thus, via the first and second data communication structures, with all other submodules as well. In other words, the connection to two submodules ensures redundancy and therefore improved robustness. According to a further embodiment of the invention, the central control unit is connected to the interface of each of the two submodules via a first and a second main data communication line. In other words, each of the two connections between the central control unit and one of the two submodules has two main data communication lines. Should one of these main data communication lines fail in one of the connections, the connection between the central control unit and the affected submodule remains active via the other main data communication line. Consequently, the two connections between the central control unit and the two submodules each contain two main data communication lines and thus exhibit redundancy, which further improves robustness. According to a further embodiment of the invention, the first main data communication line is part of the first data communication structure and the second main data communication line is part of the second data communication structure. In other words, in this embodiment, the central control unit is integrated into each of the two closed rings formed by the first and second data communication structures. According to a further embodiment of the invention, each submodule has a control unit which is configured to control and regulate the submodule based on data transmitted through the first and second data communication structures. The control unit comprises at least a processor or ASIC and memory, and is configured for data communication via the interface. The control unit may control the submodule based on data or control signals from the central control unit and / or from other submodules. In particular, the control unit can respond to data coming directly from another submodule, that is, without influence from the central control unit. The control unit can also communicate data and control signals directly to other submodules to directly control or influence their operation. According to a further embodiment of the invention, each submodule has a sensor unit which is set up to acquire measurement data and to transmit the acquired measurement data through the first and second data communication structure. The sensor unit may include, in particular, temperature sensors, voltage sensors and / or current sensors. According to a second aspect of the invention, an engine control unit for a motor vehicle is described which is configured to communicate with a system according to one of the preceding claims. The motor control of this aspect is based on the same insight as the first aspect and represents an advantageous implementation of the invention in a motor vehicle with an electric drive, that is, an electric or hybrid vehicle. The functionalities of the control units according to the invention can be implemented either by means of a computer program, i.e., software, or by means of one or more special electrical circuits, i.e., in hardware, or in any hybrid form, i.e., by means of software components and hardware components. It should be noted that embodiments of the invention have been described with reference to different subject matter. In particular, some embodiments of the invention are described by means of method claims and other embodiments of the invention by means of apparatus claims. However, it will be immediately clear to the person skilled in the art upon reading this application that, unless explicitly stated otherwise, in addition to a combination of features belonging to one type of subject matter, any combination of features belonging to different types of subject matter is also possible. Further advantages and features of the present invention will become apparent from the following exemplary description of a preferred embodiment. Fig. 1 shows an embodiment of a system according to the invention in which a plurality of submodules are connected in parallel via a double-ring structure. Fig. 2 shows an embodiment of a system according to the invention in which a plurality of submodules are connected serially via a double-ring structure. Fig. 3 shows a further embodiment of a system according to the invention in which a plurality of submodules are connected serially via a double-ring structure. It should be noted that the embodiment described below represents only a limited selection of possible embodiments of the invention. Fig. 1 shows an embodiment of a system 100 according to the invention, in which a plurality of submodules 110 are connected in parallel via a double ring structure 120, 121. System 100 comprises multiple submodules 110. Each submodule 110 serves to supply one phase of the electric motor in an electric vehicle and includes a power section 112 and a control unit 114. The power section 112 has two switching elements (MOSFETs, IGBTs, or similar), a control unit 113, and a capacitor. The control unit 113 controls the switching elements, and the capacitor stores and supplies a suitable voltage to the corresponding winding or phase of the motor. The power sections 113 are connected in series and thus share the voltage provided by a high-voltage battery 130. Depending on which of the two switching elements is currently open or closed, a portion of the battery voltage is applied to the capacitor to charge it, or the submodule 110 does not draw any voltage and leaves the battery voltage available to the other submodules 110.This allows for a flexible charging process by providing a relatively high partial voltage to some of the submodules, while the remaining submodules receive no voltage. For example, half of the submodules 110 can be charged at a time, so that twice the partial voltage is available for each submodule 110, compared to charging all submodules 110 simultaneously. The control unit 114 in each submodule 110 includes a controller 116 and data communication interfaces 118 and 119. The interfaces 118 and 119 can, for example, be optical coupling elements. Alternatively, the interfaces can be electrical or magnetic coupling elements. A first data communication line 120 runs through the interfaces 118 and the control unit 114 of each submodule 110, forming a first closed ring. A second data communication line 121 runs through the interfaces 118 and the control unit 114 of each submodule 110, forming a second closed ring. The two data communication lines 120 and 121 thus form a double ring structure. The control unit 116 in each submodule 110 is connected to each of the data communication lines 120 and 121. Therefore, in this embodiment, all submodules 110 are connected in parallel to the two data communication lines 120 and 121. Two submodules 110 (submodule A and submodule X in the figure) are connected to a central control unit 140 via interfaces 119 and main data communication lines 150, 151, 152, and 153.The central control unit 140 has a controller 142 and interfaces 144 and serves to control and monitor the system 100. The connection between the central control unit 140 and submodule A has a first main data communication line 150 and a second main data communication line 151, and the connection between the central control unit 140 and submodule X has a first main data communication line 152 and a second main data communication line 153. Thus, a second double ring structure is formed (via the data communication lines 120 and 121), which includes the central control unit 140. The submodules 110 also include (not shown) temperature sensors, current sensors, and voltage sensors. The corresponding measurement data from each submodule 110 is made available to all other submodules 110 and the central control unit 140 via the two data communication lines. Fig. 2 shows an embodiment of a system 200 according to the invention, in which a plurality of submodules 210 are serially connected via a double-ring structure 222, 223. The system 200 is identical in many respects to the system 100 described above, and only the differences will be described below to avoid unnecessary repetition. System 200 differs from System 100 in the control units 215 of the submodules 210 and in the design of the double-ring structure 222, 223. In this embodiment, these are configured such that the first data communication line 222 and the second data communication line 223 are interrupted by the controller 216, in the sense that the two data communication lines run through the controller 216 via the interfaces 218. In other words, the submodules 210 are serially connected in this embodiment by the first data communication line 222 and the second data communication line 223. Fig. 3 shows a further embodiment of a system 300 according to the invention, in which a plurality of submodules 310 are serially connected via a double-ring structure 324, 325. System 300 differs from system 200 only in that the central control unit 340 is coupled between submodule A and submodule X and is thus directly integrated into the double-ring structure 324, 325. Consequently, the control units 315' of the submodules 310 do not have an interface corresponding to the interface 219 in system 200. The systems 100, 200, and 300 according to the invention, as described above, represent flexible and robust communication systems that enable direct data communication between submodules 110, 210, and 310 and provide high reliability and fault tolerance. The system according to the invention can utilize the direct data communication between submodules to relieve the central control unit and distribute various functions across the submodules. The dual-ring structure ensures that the system can continue to operate even if a submodule or a ring fails. Data integrity is maintained, and all data (e.g., setpoint and actual values) are available to all submodules and the central control unit simultaneously (in real time). Reference symbol list 100, 200, 300 System 110, 210, 310 Submodule 112, 212, 312 Power section 113, 213, 313 Control unit 114, 216, 316 Control unit 116 Controller 118, 119 Interface 120, 121 Data communication line 130 High-voltage battery 140 Central control unit 142, 242, 342 Controller 144 Interface 150-153 Main data communication line 215 Control unit 218, 219 Interface 222, 223 Data communication line 230 High-voltage battery 240 Central control unit 244 Interface 250-253 Main data communication line 315' Control unit 318 Interface 324, 325 Data communication line 330 High-voltage battery 340 Central control unit 344 Interface

Claims

System (100) for controlling an electric machine in a motor vehicle, the system comprising a plurality of submodules (110), each submodule (110) being configured for power transmission to or from a part of the electric machine and having an interface (118, 119) for data communication, a first data communication structure and a second data communication structure, wherein both the first and the second data communication structure are connected to the interfaces of the plurality of submodules (110) in such a way that they each form a closed ring, and wherein the system (100) further comprises a central control unit (140) which is connected to the interfaces of two submodules (110). System (100) according to the preceding claim, wherein the first data communication structure has a first data communication line (120), wherein the second data communication structure has a second data communication line (121), and wherein the interfaces of the plurality of submodules (110) are connected in parallel to the first and second data communication lines (120). System (100) according to one of the preceding claims, wherein the first data communication structure comprises a first plurality of data communication lines (120, 121) which constitute a first serial connection between the interfaces of the plurality of submodules (110), and wherein the second data communication structure comprises a second plurality of data communication lines which constitute a second serial connection between the interfaces of the plurality of submodules (110). System (100) according to claim 2 or 3, wherein the first and second data communication lines (120, 121) or the first and second plurality of data communication lines are electrical, optical or magnetic data communication lines. System (100) according to one of the preceding claims, wherein the central control unit (140) is connected to the interface (118, 119) of each of the two submodules (110) via a first and a second main data communication line (150, 151). System (100) according to the preceding claim, wherein the first main data communication line is part of the first data communication structure and the second main data communication line is part of the second data communication structure. System (100) according to one of the preceding claims, wherein each submodule (110) has a control unit (114) configured to control and regulate the submodule (110) based on data transmitted through the first and second data communication structure. System (100) according to one of the preceding claims, wherein each submodule has a sensor unit which is configured to acquire measurement data and to transmit the acquired measurement data through the first and second data communication structure. Engine control unit for a motor vehicle, which is configured to communicate with a system (100) according to one of the preceding claims.

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