Energy system for electric vehicles

Abstract

The invention relates to an energy system for an electric vehicle. The electric vehicle has at least one high-voltage on-board network and at least one low-voltage on-board network, wherein the system comprises a high-voltage battery, which is connected to the at least one high-voltage on-board network via an interrupting element, wherein the high-voltage battery comprises a first branch and a second branch connected in series, wherein an input of a first DC / DC converter comprising a first transformer is connected to the first branch and an output of the first DC / DC converter is connected to the at least one low-voltage on-board network, and an input of a second DC / DC converter comprising a second transformer is connected to the second branch and an output of the second DC / DC converter is connected to the at least one low-voltage on-board network. Furthermore, the invention relates to a method for supplying an electric vehicle with electrical energy.

Description

Technical Field

[0001] The present invention relates to a system for supplying electrical energy to a vehicle and a method for supplying electrical energy to a vehicle. Background Technology

[0002] In today's electrically driven vehicles, such as plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), or hybrid electric vehicles (HEVs) equipped with high-voltage energy storage (high-voltage batteries), DC-DC converters are used to power the low-voltage on-board network (LCN). The DC-DC converter is primarily powered by the high-voltage battery and is connected to the overall system voltage after the battery contactor. Currently, these high-voltage networks are not subject to any ASIL safety classification and are therefore only conditionally applicable, or, depending on type, completely unsuitable, for applications with highly automated driver assistance systems.

[0003] WO 2018 / 108 779 A1 relates to an apparatus for generating a shifted DC voltage, comprising a transformer, a rectifier module, and a DC voltage conversion module, wherein the transformer has a primary circuit and a secondary circuit. A first rectifier is placed after the primary circuit, and a second rectifier is placed after the secondary circuit; a first shifted DC voltage converter is placed after the first rectifier, and a second shifted DC voltage converter is placed after the second rectifier; wherein the secondary DC voltage converter is implemented as a two-stage buck chopper.

[0004] CN 106 357 116 A discloses a main circuit and a control method for a charging and discharging device in a microgrid system. The main circuit consists of a control circuit, a power direction control module, a grid interface, a filter circuit module, a bidirectional DC / AC rectifier module, a bidirectional DC / DC converter module, and an energy storage battery pack connected in sequence. The circuit breaker module includes contactors KM1 and KM2, and an AC current H-bridge single-phase inverter is connected to the primary and secondary sides of a transformer via contactor KM1 or contactor KM2. The control circuit and power direction control module acquire signals from the grid interface, filter circuit module, bidirectional DC / AC rectifier module, bidirectional DC / DC converter module, energy storage battery pack, and circuit breaker module. Switching between different current paths for charging and discharging in the microgrid system is accomplished by switching the contactor connected to the primary side of the high-frequency transformer according to charging and discharging commands.

[0005] CN 102 185 493 A relates to an isolated DC / DC converter and is designed to provide a combined current converter capable of emergency regulation of the output via a series connection on the high-frequency AC current side. The combined current transformer includes two transformers, wherein the primary windings of the two transformers are connected in series and to both ends of an AC input source. The output of the secondary winding of transformer T1 is connected to the input of rectifier circuit Rec1; the output of the secondary winding of transformer T2 is connected to the input of rectifier circuit Rec2. One end of the output of rectifier circuit Rec1 is connected to the positive end of output capacitor Co, and the other end of the output of rectifier circuit Rec1 is connected to the negative end of output terminal Vo; one end of load RL is connected to the positive end of output capacitor Co, and the other end of load RL is connected to the negative end of output terminal Vo; and the output of rectifier circuit Rec2 has two alternative paths. The primary side of the combined current converter can achieve a fixed duty cycle, thereby maximizing the load on transformers T1 and T2; feedback control signals do not need to be transmitted to the primary side, thus improving the reliability of feedback control; modularization of multiple path-independent outputs can be easily achieved; and the secondary side rectifier circuit is more likely to adopt synchronous rectification technology. Summary of the Invention

[0006] In this context, the object of the present invention is to reliably supply electrical energy to the low-voltage on-board network of electric vehicles, and the electrical energy also meets the safety standards for highly automated driving assistance systems.

[0007] The subject of this invention is a system for supplying electrical energy to an electric vehicle having at least one high-voltage on-board network and at least one low-voltage on-board network.

[0008] In the context of this specification, a high-voltage vehicle network is a high-voltage vehicle network having a potential value exceeding 200V, particularly in the range of 300V to 1200V, such as 400V or 800V. A high-voltage battery is a high-voltage energy storage device having a rated output voltage in the range of 300V to 1200V, such as 400V or 800V. A low-voltage vehicle network is a low-voltage vehicle network having a potential value less than 100V, particularly in the range of 10 to 60V, such as 12V or 48V.

[0009] The system configuration according to the invention is used to supply electrical energy to an electric vehicle, wherein the vehicle has multiple electrical components (typically power consumers or power sources). The system is arranged within the vehicle and includes a high-voltage battery or accumulator having two series-connected lines, each having at least one energy storage unit. Each line has at least one energy storage unit, such as a battery cell, wherein multiple energy storage units may be connected in series and / or in parallel with each other in the respective lines.

[0010] The electrodes of the high-voltage battery are connected to the vehicle's high-voltage on-board network via interrupting elements (e.g., battery contactors). The high-voltage on-board network includes: the vehicle's high-voltage generator set, such as motors for driving, heating, and cooling the generator set; and charging modules for charging the high-voltage battery with AC and / or DC current. The input modules of the DC / DC converter are connected to the electrodes of the two lines of the high-voltage battery, respectively. In one embodiment, the DC / DC converter includes a DC / AC conversion unit connected to the primary winding of a transformer and an AC / DC conversion unit connected to the secondary winding of the transformer. In one embodiment, the DC / AC conversion unit is implemented as a full-bridge. Other topologies may also be used depending on the power requirements and voltage variation range on the high-voltage side. In one embodiment, the DC / AC conversion unit is implemented as a half-bridge. In another embodiment, the DC / AC conversion unit is implemented as a resonant converter. In one embodiment, a center tap (center tap technology) is used on the secondary winding side. Other topologies may also be used here. In one embodiment, an active full-bridge is used on the secondary side. In another embodiment, a passive or active rectifier is used. In yet another embodiment, a current multiplier is used.

[0011] The energy system according to the invention is characterized by achieving higher voltage supply availability through the center tap of the high-voltage battery. Additionally, the DC / DC converter is moved before the main contactor so that the supply voltage is not disconnected in the event of a QM power consumption failure. Power supply to the low-voltage on-board network is still ensured in the event of a failure.

[0012] Two sub-groups are formed by the center tap of the high-voltage battery, each having half of the system voltage. The energy system according to the invention comprises a DC / DC converter topology with two completely independent power paths for each of the two battery groups. Up to two low-voltage feed-in points can be achieved through the two independent (or redundantly implemented) secondary paths. During normal operation, each phase directs half of the power to the transformer. In the event of a battery group failure, the remaining phase can output the full power to the low-voltage on-board network. This topology demonstrates two independent feed-in points into the low-voltage grid. Thus, on the one hand, better energy distribution can be achieved within a common network, or two independent sub-networks can be provided.

[0013] In one embodiment, the output voltages of the two DC / DC converters are identical. In another embodiment, the outputs of the two DC / DC converters are converged to form a common feedpoint for the low-voltage automotive network. In yet another embodiment, the outputs of the DC / DC converters form two feedpoints for the low-voltage automotive network. In still another embodiment, the outputs of the DC / DC converters form two feedpoints for two independent subnetworks of the low-voltage automotive network.

[0014] In another embodiment, the output voltages of the two DC / DC converters are different. In yet another embodiment, the outputs of the DC / DC converters form two feed points for two independent subnetworks of a low-voltage vehicle network. In an exemplary embodiment, the output voltage of one DC / DC converter is 12V, while the output voltage of the other DC / DC converter is 48V.

[0015] It is possible that the DC / DC converter is placed outside the energy storage device as an external component, or placed inside the energy storage device as an internal component and integrated therein.

[0016] The present invention also relates to a method for supplying electrical energy to a vehicle having at least one high-voltage on-board network and at least one low-voltage on-board network, and including a high-voltage battery comprising a first branch and a second branch connected in series. In this method, at least one high-voltage on-board network is connected to the electrodes of the high-voltage battery and is supplied with electrical energy, and at least one low-voltage on-board network is connected to the outputs of a first DC / DC converter (whose input module is connected to the first branch) and a second DC / DC converter (whose input module is connected to the second branch) and is supplied with electrical energy.

[0017] In one embodiment, the output voltage of the high-voltage battery has a value in the range of 200V to 1200V, for example, in the range of 400V to 800V.

[0018] In one implementation, the output voltage of the DC / DC converter has a value in the range of 10V to 60V, for example, in the range of 12V to 48V.

[0019] In one embodiment of the method, the output voltages of the first and second DC / DC converters are the same. In another embodiment of the method, the output voltages of the first and second DC / DC converters are different.

[0020] In this method, a high-voltage battery and two DC / DC or DC current / DC current converters are used. The high-voltage battery has two lines, each with at least one energy storage unit. A corresponding line of the energy storage unit and a corresponding input module of the DC / DC converter are interconnected on both sides by the lines. The electrodes of the high-voltage energy storage unit provide a high-voltage voltage to at least one high-voltage circuit, and the outputs of the two DC / DC converters provide at least one low-voltage voltage to at least one low-voltage circuit of the vehicle.

[0021] It is possible that one implementation of this method utilizes one implementation of the proposed system.

[0022] Here, it is more feasible to provide at least one low-voltage circuit than at least one high-voltage circuit.

[0023] In this method, electrical energy can be exchanged unidirectionally or bidirectionally between the high-voltage battery circuitry or its energy storage unit and at least one component of the high-voltage vehicle network. It is possible that electrical energy is supplied from the high-voltage battery, i.e., from at least one circuitry of the high-voltage battery. Correspondingly, it is possible to use the electrical energy from at least one component to charge at least one circuitry of the high-voltage battery, or to charge the component and store the electrical energy therein. The component, for example, is configured as a motor for driving the vehicle, which, in operating mode as a motor, converts electrical energy from the high-voltage battery into mechanical energy and moves the vehicle. In operating mode as a generator, the motor, for example, converts mechanical energy into electrical energy based on motion during recovery, and the electrical energy is stored in the high-voltage battery. It is also possible that the component is configured, for example, as a fuel cell and thus as a power source, whose electrical energy can also be stored in the high-voltage battery. At least one additional component can be configured as an actuator, sensor, and / or device of the vehicle, for example, configured as at least one control device of the vehicle.

[0024] In implementing this method and system, a highly available power supply to the vehicle's low-voltage on-board network is provided through the aforementioned structure of the DC / DC converter and its connection to the high-voltage battery lines. Here, the low-voltage on-board network is supplied with electrical energy from two lines of the high-voltage battery via two DC / DC converters. The high-voltage battery lines (which may also be referred to as branches) and the input modules of the DC / DC converters form a parallel power supply path for components of the low-voltage on-board network, such as power consumers. Here, a possible fault in the lines will not lead to a failure in the power supply to the low-voltage on-board network, especially a complete failure, because the availability of the low-voltage on-board network is enhanced based on the parallel arrangement of the lines. The high-voltage battery can be implemented using a variable battery concept, where it is conceivable that the lines have different numbers of energy units and / or energy units of different configurations, such as battery cells and / or capacitors. Based on the parallel power supply achieved through the two DC / DC converters, a fault in the input module will not lead to a failure in the power supply to the low-voltage on-board network.

[0025] It should be understood that the features described above and will be set forth below may be used not only in the corresponding combinations but also in other combinations or individually, without departing from the scope of protection of the present invention. Attached Figure Description

[0026] The present invention is schematically illustrated in the accompanying drawings according to embodiments, and is described schematically and in detail with reference to the accompanying drawings.

[0027] Figure 1 A partial diagram of an embodiment of a system according to the invention for performing an embodiment of the method according to the invention is shown in schematic diagram. Detailed Implementation

[0028] Figure 1 A partial diagram schematically illustrates an embodiment of the energy system 100 according to the present invention. The connection between the high-voltage battery 10 and the high-voltage vehicle network, the vehicle's high-voltage vehicle network, and the low-voltage vehicle network are not shown.

[0029] The high-voltage battery 10 has a first branch 11 and a second branch 12. A first DC / DC converter 21 with a transformer 31 having a center tap is connected to the first branch 11. A second DC / DC converter 22 with a transformer 32 having a center tap is connected to the second branch 12. The high-voltage bridge on the primary side of the transformers 31 and 32 is implemented as a full bridge. The center tap is used on the secondary side of the transformers 31 and 32 (center tap technology). The redundant implementation of the DC / DC converters 21 and 22 improves the availability of the low-voltage vehicle network connected to the output of the DC / DC converters 21 and 22, thereby preventing the disconnection of the highly available low-voltage vehicle network in the event of a failure or malfunction of the branches 11 and 12 of the high-voltage battery 10. The DC / DC converters 21 and 22 for powering the low-voltage vehicle network are located before the main contactor of the high-voltage battery 10.

[0030]

Claims

1. A system (100) for supplying electrical energy to a vehicle, the vehicle having at least one high-voltage on-board network and at least one low-voltage on-board network, wherein, The system (100) includes a high-voltage battery (10) connected to at least one high-voltage vehicle network via an interruption element. The high-voltage battery (10) includes a first branch (11) and a second branch (12) connected in series. The input of a first DC / DC converter (21) including a first transformer (31) is connected to the first branch (11), and the output of the first DC / DC converter is connected to at least one low-voltage vehicle network. The input of a second DC / DC converter (22) including a second transformer (32) is connected to the second branch (12), and the output of the second DC / DC converter is connected to at least one low-voltage vehicle network. The first DC / DC converter and the second DC / DC converter are switched to the interruption element before the interruption element so as not to disconnect from the supply voltage in the event of a failure of at least one high-voltage vehicle network.

2. The system according to claim 1, wherein, The first DC / DC converter (21) and the second DC / DC converter (22) have full bridges on the primary side of the first transformer (31) and the second transformer (32), respectively.

3. The system according to claim 1, wherein, The first DC / DC converter (21) and the second DC / DC converter (22) have half-bridges on the primary side of the first transformer (31) and the second transformer (32), respectively.

4. The system according to claim 1, wherein, The first DC / DC converter (21) and the second DC / DC converter (22) have resonant converters on the primary side of the first transformer (31) and the second transformer (32), respectively.

5. The system according to any one of claims 1 to 4, wherein, The first DC / DC converter (21) and the second DC / DC converter (22) use the center taps of the first transformer (31) and the second transformer (32) respectively on the secondary side of the first transformer (31) and the second transformer (32).

6. The system according to any one of claims 1 to 4, wherein, The first DC / DC converter (21) and the second DC / DC converter (22) have active or passive rectifiers on the secondary side of the first transformer (31) and the second transformer (32), respectively.

7. The system according to any one of claims 1 to 4, wherein, The first DC / DC converter (21) and the second DC / DC converter (22) have active full bridges on the secondary side of the first transformer (31) and the second transformer (32), respectively.

8. The system according to any one of claims 1 to 4, wherein, The first DC / DC converter (21) and the second DC / DC converter (22) have current multipliers on the secondary side of the first transformer (31) and the second transformer (32), respectively.

9. The system according to any one of claims 1 to 4, wherein, The first DC / DC converter (21) is configured to provide a first potential value at the output terminal of the first DC / DC converter, and the second DC / DC converter (22) is configured to provide a second potential value at the output terminal of the second DC / DC converter.

10. A method for supplying electrical energy to a vehicle, the vehicle having at least one high-voltage on-board network and at least one low-voltage on-board network, and including a high-voltage battery (10) connected to the at least one high-voltage on-board network via an interrupting element, the high-voltage battery including a first branch (11) and a second branch (12) connected in series, wherein in the method, the at least one high-voltage on-board network is connected to the electrodes of the high-voltage battery (10) and supplied with electrical energy, the at least one low-voltage on-board network is connected to the output of a first DC / DC converter (21) and to the output of a second DC / DC converter (22) and supplied with electrical energy, the input module of the first DC / DC converter is connected to the first branch (11), and the input module of the second DC / DC converter is connected to the second branch (12), wherein, The first DC / DC converter and the second DC / DC converter are transferred before the interruption element so as not to be disconnected from the supply voltage in the event of a failure of at least one high-voltage on-board network.

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