CHARGING DEVICE AND ELECTRIC VEHICLE

Abstract

The invention relates to a charging device configured for installation in an electric vehicle to charge the vehicle's traction battery. The charging device comprises a wireless power transfer (WPT) unit (310), an on-board battery (OBC) unit (320), a rectifier unit (330, 400) connected to the WPT unit and the OBC unit, and an output (340) configured to connect to the electric vehicle's traction battery (301) to supply it with direct current.The rectifier unit comprises three rectifier branches (410, 420, 430) of rectifier switching elements, wherein a first rectifier branch (410) and a second rectifier branch (420) are connected to the OBC unit and form a full-bridge rectifier configured to rectify alternating current provided by the OBC unit, and wherein the second rectifier branch (420) and a third rectifier branch (430) are connected to the WPT unit and form a full-bridge rectifier configured to rectify alternating current provided by the WPT unit.

Description

[0001] The present invention relates to a charging device and an electric vehicle.

[0002] US 2018 / 0290545 A1 discloses a vehicle including a traction battery, an on-board charging (OBC) system, and a wireless power transfer (WPT) system. Both the OBC system and the WPT system are configured to selectively use the same rectifier, such that the rectifier rectifies the output of the OBC system and rectifies the output of the WPT system to supply power to the traction battery.

[0003] WPT, which uses magnetic resonance, is the technology that could free people from cumbersome cables. WPT is actually based on the same theory that has been developed for at least 30 years under the name of inductive power transfer. WPT technology has developed rapidly in recent years. At power levels of several kilowatts, the distance between the grid and the load increases from a few millimeters to several hundred millimeters, with an efficiency of over 90%. These advances make WPT very attractive for charging applications in electric vehicles (EVs), both in stationary and dynamic charging scenarios. By introducing WPT into EVs, the obstacles of charging time, range, and cost can be easily overcome, and battery technology becomes less of a factor in the EV market.

[0004] When converting alternating current (AC) to low-voltage direct current (DC) or AC from one frequency to another during energy conversion, the AC is typically rectified and smoothed to obtain a fixed voltage at a fixed frequency. Once this is achieved, the current is passed to an inverter to obtain the final output with variable voltage and variable frequency.

[0005] EP 3694079 A1 discloses a WPT system for an electric vehicle (EV), wherein the WPT system comprises a ground assembly (GA) including a transmitter coil and a vehicle assembly (VA) including a receiver coil, which is magnetically coupled to the GA transmitter coil to transfer inductive energy from the GA to the VA to charge a traction battery of the EV. Furthermore, an on-board battery (OBB) system is connected to the traction battery in parallel with the WPT system.

[0006] Generally, on-board charging (OBC) and water-to-power charging (WPT) systems do not share large portions of an electronic stage and are installed separately in EVs (depending on the configuration). Architecture optimization can only be achieved by integrating both systems into a common package and sharing certain components (e.g., connectors, output filters, etc.). Separate control systems require arbitration / synchronization by a higher-level control system within the vehicle architecture. Furthermore, simultaneous charging may not be desirable.

[0007] Currently, no integrated system is available on the market. Costs and system complexity typically increase when both systems (OBC and WPT) are planned for use in a single vehicle. In some cases, complex and expensive switches have been proposed to allow switching between the systems depending on the application. Coordination of the charging process (OBC vs. WPT) may be required at the vehicle level, which necessitates additional effort.

[0008] The objective of the present invention is to provide a charging system that integrates an on-board computer (OBC) unit and a water-to-plate (WPT) unit with reasonable complexity and cost. Furthermore, it is an objective of the present invention to provide a corresponding electric vehicle.

[0009] In a first aspect of the present invention, a charging device is presented which is configured for installation in an electric vehicle for charging a traction battery of the electric vehicle, wherein the charging device comprises: - a wireless power transfer (WPT) unit with a WPT receiving coil configured to inductively receive electrical energy from a WPT transmitting coil; - an on-board charging (OBC) unit with an OBC input configured to connect a power supply connector for supplying electrical power from a power supply system; - a rectifier unit connected to the WPT unit and the OBC unit and configured to convert alternating current supplied by the WPT unit or the OBC unit into direct current; and - an output configured to connect to the electric vehicle's traction battery to supply the traction battery with direct current, wherein the rectifier unit comprises three rectifier branches of rectifier switching elements, wherein a first rectifier branch and a second rectifier branch are connected to the OBC unit and form a full-bridge rectifier configured to rectify alternating current supplied by the OBC unit and wherein the second rectifier branch and a third rectifier branch are connected to the WPT unit and form a full bridge rectifier configured to rectify alternating current supplied by the WPT unit.

[0010] In another aspect of the present invention, an electric vehicle is presented which comprises a traction battery and a charging device disclosed herein for charging the traction battery.

[0011] Preferred embodiments of the invention are defined in the dependent claims. It is understood that the claimed electric vehicle has similar and / or identical preferred embodiments to the claimed charging device, in particular as defined in the dependent claims and as disclosed herein.

[0012] The present invention is based on the idea of ​​sharing the rectifier unit between the OBC unit and the WPT unit. For this purpose, an additional (second) rectifier branch is added, which is shared and used either together with a first rectifier branch to rectify the alternating current supplied by the OBC unit or together with a third rectifier branch to rectify the alternating current supplied by the WPT unit. This represents a cost-effective solution that requires only a minimum of additional hardware and space. Additional switches, such as those used in known charging devices, can be avoided, and the use of the second rectifier branch makes it possible to properly isolate the OBC unit and the WPT unit.

[0013] Active rectifier components (IGBTs, SiC, GaN, etc.) of a conventional WPT system can be added to a current passive (or active) rectifier circuit of a conventional OBC system to enable both charging modes. A basic electronics architecture can be used to combine both output stages and avoid the need for subsystem power switches. The additional second rectifier branch provides this combination. In one embodiment, the active rectifier of a conventional WPT system with two rectifier branches can be used as the second and third rectifier branches. An additional rectifier branch is added as the first rectifier branch. In other words, one rectifier branch of the active rectifier of the conventional WPT system is shared with the OBC unit.

[0014] In one embodiment, a first output terminal of the OBC unit and a first output terminal of the WPT unit are connected to an input terminal of the second rectifier branch. Furthermore, in another embodiment, a second output terminal of the OBC unit is connected to an input terminal of the first rectifier branch, and a second output terminal of the WPT unit is connected to an input terminal of the third rectifier branch. In yet another embodiment, the first output terminals of the three rectifier branches are connected to each other, and the second output terminals of the three rectifier branches are connected to each other. This enables a meaningful connection of the rectifier branches, allowing for simple and efficient control and switching of the rectifier circuit elements.

[0015] In a preferred embodiment, each rectifier branch comprises two rectifier switching elements, in particular semiconductor switching elements. These can be active rectifier components (IGBTs, SiC, GaN, etc.).

[0016] In one embodiment, the charging device further comprises a control unit configured to control the rectifier switching elements. The control unit can be implemented in hardware and / or software, e.g., as a controller or processor that executes a control algorithm.

[0017] The control unit can be configured to detect whether AC power is supplied by the OBC unit or the WPT unit, and to open the rectifier switching elements of the first rectifier branch when AC power is supplied by the WPT unit, and to open the rectifier switching elements of the third rectifier branch when AC power is supplied by the OBC unit. This prevents simultaneous charging of the traction battery by the OBC unit and the WPT unit.

[0018] The control unit can also be configured to open the rectifier switching elements of the second rectifier branch when neither the WPT unit nor the OBC unit is supplying AC power. This provides isolation from external influences (e.g., grid overvoltage or interference power in multi-GA systems) and ensures a safe EV environment (vehicle AC connector without voltage at the power pins). Furthermore, it prevents potential internal currents (no closed circuit when not charging), thus avoiding high-voltage battery discharge.

[0019] In another embodiment, the OBC unit and / or the WPT unit are configured for bidirectional power transfer, and the control unit is configured to control the rectifier switching elements according to the direction of power transfer. This allows current to flow from the OBC unit or the WPT unit to the traction battery or vice versa, i.e., it allows current to flow from the grid to the vehicle and from the vehicle to the grid.

[0020] In one embodiment, the rectifier unit comprises one or more further rectifier branches, wherein the second rectifier branch and one of the further rectifier branches are connected to another AC power supply unit and form a full-bridge rectifier configured to rectify the alternating current supplied by the further AC power supply unit. This allows the use of one or more additional power supplies with which the second rectifier unit is shared, thus saving many additional components.

[0021] The charging device can also include a housing that accommodates both the OBC unit and the WPT unit. This saves space and time compared to assembling two separate units.

[0022] The preceding sections serve as a general introduction and are not intended to limit the scope of the following claims. A more comprehensive assessment of the disclosure and many of the associated advantages will be readily possible, as these will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, wherein: Fig. 1 shows a schematic diagram of the general structure of a WPT system for an EV; Fig. 2 shows a schematic diagram of a generally known OBC system for an EV; Fig. 3 shows a schematic diagram of a charging device according to the present invention; Fig. 4 shows a circuit diagram of an embodiment of a rectifier unit according to the present invention; Fig. 5 The rectifier unit shows how it is installed in Fig. Figure 4 shows the full-bridge rectifier used for OBC charging; Fig. 6 The rectifier unit shows how it is installed in Fig. Figure 4 shows the full-bridge rectifier used for WPT charging; Fig. 7 a circuit diagram of an embodiment of a further rectifier unit according to the present invention.

[0023] Fig. Figure 1 shows a schematic diagram of a generally known WPT system 100 for an EV 120, as disclosed, for example, in EP 3694079 A1. In this WPT system 100, the basic functional blocks for inductive charging are shared by a ground assembly (GA) 101 and a vehicle assembly (VA) 102, each of which represents a separate WPT device of the WPT system 100. The WPT system 100 comprises an inductive charging coil assembly 112, which includes a transmitter coil (also called transmit coil or GA coil) 107 on the GA side and a receiver coil (also called receive coil or VA coil) 108 on the vehicle side.

[0024] The GA 101 of the WPT system 100 comprises an AC / DC converter 104 with power factor correction (PFC), which converts the single- or three-phase current supplied by an (external) AC power source 103 into a regulated DC current. The GA 101 also includes a DC-to-RF AC converter 105, which generates a square wave voltage with a nearly constant frequency and constant duty cycle. A primary compensation circuit 106, which is a passive circuit network, compensates for the inductance of the transmitter coil to reduce the reactive power supplied by the DC-to-RF AC converter 105. The transmitter coil 107 transfers energy through a magnetic field and provides additional isolation between the AC input and the vehicle's high-voltage (HV) battery 111 (also called the traction battery).

[0025] The VA 102 includes a receiver coil 108, which picks up the current through the magnetic field and enhances the insulation between the AC input and the vehicle's high-voltage battery 111. A secondary compensation circuit 109, a passive circuit network, compensates for the inductance of the receiver coil to maximize the power transferred at electrical resonance. The VA 102 includes an (active or passive) AC / DC rectifier 110, which converts high-frequency AC current to DC current to charge the vehicle's high-voltage battery. A DC / DC battery charger (including or without battery charging algorithms / strategy) may be provided. The VA 102 may include the high-voltage battery 111 or be connected to it.

[0026] The architecture of the VA can differ depending on many criteria, including grid compensation or the charging / discharging strategy. Charging the high-voltage battery 111 can potentially be handled by both assemblies, the GA 101 and the VA 102 of the WPT system 100, thus enabling the determination of an optimal WPT architecture.

[0027] Fig. Figure 2 shows a schematic diagram of a generally known OBC system 200 for an EV 120. It comprises an AC / DC converter 202 with PFC, which converts the single- or three-phase current supplied by an (external) AC power source 201 into a regulated DC current. The OBC system 200 further comprises a DC-to-RF AC converter 203, which generates a square wave voltage with a variable or constant frequency depending on the battery's operating point and the power required. A resonant tank 204 ensures power transfer at resonance to maximize the efficiency of the power converter. A high-frequency transformer 205 provides isolation between the AC network (components 203, 204) and the vehicle's HV battery 208, which is connected to the Fig. This corresponds to the vehicle AV battery 111 shown. A rectifier 206 converts high-frequency alternating current into direct current to charge the vehicle HV battery 208. It can be an active or passive rectifier, e.g., with diodes, IGBTs, MOSFETs, etc. One or more control and protection boards 207 can be provided to control and protect the components of the OBC system 200.

[0028] Assuming that both charging systems, i.e., the WPT System 100 and the OBC System 200, are used and implemented separately, sufficient space must be provided in the vehicle for the installation of both charging systems, including one or more electrical wiring harnesses and connectors for high and low voltage supply, communication, cooling hoses, and connectors, etc. Furthermore, separate control systems are provided, requiring arbitration and synchronization from a higher level. This increases costs, complexity, space requirements, and other effort.

[0029] Fig. Figure 3 shows a schematic diagram of a charging device 300 according to the present invention, configured for installation in an EV for charging a traction battery 301 of the EV. The charging device 300 comprises a WPT unit 310 with a WPT receiving coil 311 configured to inductively receive electrical power from a WPT transmitting coil (107 in Fig. 1; in Fig. 3 not shown and not part of the charging device 300). The power device 300 further comprises an OBC unit 320 with an OBC input 321 configured to provide a power supply connector for supplying electrical power from a power supply system, such as an AC power source (201 in Fig. 2; in Fig. 3 (not shown and not part of the charging device 300). A rectifier unit 330 is connected to the WPT unit 310 and the OBC unit 320 and configured to convert the alternating current provided by the WPT unit 310 or the OBC unit 320 into direct current; that is, the rectifier unit 330 is shared by the WPT unit 310 and the OBC unit 320. An output 340, e.g., an output filter, is provided, configured to connect to the traction battery 301 of the electric vehicle to supply the traction battery 301 with direct current. Preferably, a control unit 350 is provided to control the rectifier unit 330, and a capacitor 360 (acting as a DC link) is provided between the rectifier unit 330 and the output 340. Details and embodiments of the rectifier unit 330 are discussed below.

[0030] In preferred embodiments, the WPT unit 310 comprises a compensation network 312, in particular for compensating reactive power. The compensation network can be used as a primary compensation circuit (106 in Fig. 1) be implemented, e.g. as a passive circuit network that compensates for the inductance of the transmitter coil to reduce the output of a DC-to-RF AC converter (105 in Fig. 1) to reduce the reactive power supplied.

[0031] In preferred embodiments, the OBC unit 320 comprises an AC / DC converter 322 (preferably) with PFC, which converts the AC current supplied by an (external) AC power source (201 in Fig. 2; in Fig. 3 (not shown) provides single- or three-phase power into regulated DC power, which, like the one in Fig. The AC / DC converter 202 shown in Figure 2 can be implemented. The OBC unit 320 further comprises a capacitor 323 (which acts like a DC link) and a DC-to-RF AC converter 324, which generates a square wave voltage with variable or constant frequency depending on the battery's operating point and the power required, and as shown in Figure 2. Fig. The two DC-to-RF (high-frequency) AC-to-DC converters 203 shown can be implemented. An RF transformer 326 with a compensation network 325, 327 at its input and output, respectively, provides isolation between the RF-to-AC converter 324 and the battery 301 and can be implemented like the one shown in Fig. The 2 RF transformer 205 shown will be implemented.

[0032] Fig. Figure 4 shows a circuit diagram of an embodiment of a rectifier unit 400, which is referred to as rectifier unit 330 in Fig. The rectifier unit 400 is coupled on the input side to the WPT unit 310 and the OBC unit 320, which are connected in the same way as shown in Figure 3. Fig. Figure 3 shows how it can be implemented, but it can also be implemented in other ways. At its output, the rectifier unit 400 is coupled to the HV battery 301.

[0033] The rectifier unit 400 comprises three rectifier branches 410, 420, 430, each of which includes rectifier switching elements, in this embodiment each comprising two rectifier switching elements 411, 412, 421, 422, 431, 432. The first rectifier branch 410 and the second rectifier branch 420 are connected to the OBC unit 320 and form a full-bridge rectifier 440, which is configured to rectify alternating current supplied by the OBC unit 320. This is described in Fig. Figure 5 illustrates the rectifier unit 400, as shown in Fig. Figure 4 shows the full-bridge rectifier 440. The second rectifier branch 420 and the third rectifier branch 430 are connected to the WPT unit 310 and form a full-bridge rectifier 450, which is configured to rectify the alternating current supplied by the WPT unit 310. This is shown in Fig. Figure 6 illustrates the rectifier unit 400, as shown in Fig. Figure 4 shows the full-bridge rectifier 450. The second rectifier branch is thus shared by the WPT unit 310 and the OBC unit 320 and is used either together with the first rectifier branch 410 or the third rectifier branch 430, but generally not simultaneously with both rectifier branches.

[0034] In one embodiment, a first output terminal 328 of the OBC unit 320 and a first output terminal 318 of the WPT unit 310 are connected to an input terminal 423 of the second rectifier branch 420. A second output terminal 329 of the OBC unit 320 is connected to an input terminal 413 of the first rectifier branch 310, and a second output terminal 319 of the WPT unit 310 is connected to an input terminal 433 of the third rectifier branch 330.

[0035] Furthermore, in one embodiment, the first output terminals 414, 424, 434 of the three rectifier branches 410, 420, 430 are connected to each other and to the first input terminal 301a of the battery 301. The second output terminals 415, 425, 435 of the three rectifier branches 410, 420, 430 are connected to each other and to the second input terminal 301b of the battery 301.

[0036] The control unit (350 in Fig. 3) Controls the rectifier switching elements 411, 412, 421, 422, 431, 432 to perform the desired rectification of the alternating current supplied by the WPT unit 310 or the OBC unit 320. The control unit preferably detects whether the alternating current is supplied by the OBC unit 320 or by the WPT unit 310. When alternating current is supplied by the WPT unit 310, it opens the rectifier switching elements 411, 412 of the first rectifier branch 410. When alternating current is supplied by the OBC unit 320, it opens the rectifier switching elements 431, 432 of the third rectifier branch 430. Werner, when no alternating current is supplied by the WPT unit 310 and no alternating current is supplied by the OBC unit 320, the control unit opens the rectifier switching elements 421, 422 of the second rectifier branch 420.

[0037] Generally, unused switching branches, i.e., switching branches connected to power sources that are not present or do not supply power, are controlled to remain open circuits to prevent unwanted currents in the vehicle. In the specific case of a charging device that has wired and wireless charging units, such as in the [reference to a specific example would be inserted here] Fig. 3, Fig. 4, Fig. 5 to Fig. In the embodiment shown in Figure 6, several switching strategies can be employed. Preferably, when charging in wired mode, all rectifier switching elements of the non-shared branch of the rectifier unit should remain open to prevent current from flowing through the WPT unit. The same applies to wireless charging; to isolate the OBC unit, all rectifier switching elements not shared with the wireless mode should remain open while wireless charging is in progress.

[0038] Fig. Figure 7 shows a circuit diagram of another embodiment of a rectifier unit 500, which is referred to as rectifier unit 330 in Fig. Figure 3 shows how the rectifier unit 500 can be used. In this embodiment, in addition to the three rectifier branches 410, 420, and 430, the rectifier unit 500 includes a further rectifier branch 440 (there can also be two or more further rectifier branches). The second rectifier branch 420 and the further rectifier branch 510 are connected to a further AC power supply unit 520 and form a full-bridge rectifier configured to rectify the alternating current supplied by the further AC power supply unit 520. A first output terminal 528 of the further AC power supply unit 520 is connected to the input terminal 423 of the second rectifier branch 420. A second output terminal 529 of the further AC power supply unit 520 is connected to an input terminal 513 of the further rectifier branch 510.

[0039] The additional AC power supply unit 520 can, for example, include a fuel cell or another electrical energy source or a generator. In general, according to embodiments of the present invention, several charging sources (e.g., including fuel cell vehicles or low-voltage DC-DC converters) can be provided, which share a rectification and output filter stage.

[0040] In another embodiment, bidirectionality can be added to the capable subsystems, and a single common control can be provided, e.g., by the control unit 350. The OBC unit 320 and / or the WPT unit 310 can therefore be configured for bidirectional power transmission, and the control unit 350 can be configured to control the rectifier switching elements according to the direction of power transmission.

[0041] In another embodiment, the charging device further comprises a housing 370 (as in Fig. 3 shown), which typically accommodates the OBC unit 320 and the WPT unit 310, preferably all components of the charging device 300.

[0042] As explained above, the charging device of the present invention can be advantageously used in an electric vehicle comprising a traction battery and the charging device for charging the traction battery.

[0043] While the invention has been illustrated and described in detail in the drawings and the preceding description, this illustration and description are to be considered illustrative or exemplary and not limiting; the invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments can be understood and carried out by a person skilled in the art when carrying out the claimed invention with reference to the drawings, the disclosure, and the accompanying claims.

[0044] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit can perform the functions of several elements listed in the claims. The mere fact that certain dimensions are specified in different dependent claims does not indicate that a combination of these dimensions cannot be used advantageously.

[0045] Any reference punctuation in the claims shall not be interpreted as limitations of the scope of protection. QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] US 2018 / 0290545 A1

[0002] EP 3694079 A1 [0005, 0023]

Claims

[1] Charging device configured for installation in an electric vehicle for charging a traction battery of the electric vehicle, the charging device comprising: - a wireless power transfer (WPT) unit (310) with a WPT receiving coil (311) configured to inductively receive electrical energy from a WPT transmitting coil; - an on-board charging (OBC) unit (320) with an OBC input (321) configured to connect a power supply connector for supplying electrical power from a power supply system; - a rectifier unit (330, 400) connected to the WPT unit and the OBC unit and configured to convert alternating current supplied by the WPT unit or the OBC unit into direct current; and - an output (340) configured to connect to the traction battery (301) of the electric vehicle to provide direct current to the traction battery, wherein the rectifier unit comprises three rectifier branches (410, 420, 430) of rectifier switching elements, wherein a first rectifier branch (410) and a second rectifier branch (420) are connected to the OBC unit and form a full-bridge rectifier configured to rectify alternating current supplied by the OBC unit and wherein the second rectifier branch (420) and a third rectifier branch (430) are connected to the WPT unit and form a full bridge rectifier configured to rectify alternating current supplied by the WPT unit. [2] Charging device according to claim 1, wherein a first output terminal (328) of the OBC unit and a first output terminal (318) of the WPT unit are connected to an input terminal (423) of the second rectifier branch (). [3] Charging device according to claim 1 or 2, wherein a second output terminal (329) of the OBC unit is connected to an input terminal (413) of the first rectifier branch (410) and a second output terminal (319) of the WPT unit is connected to an input terminal (433) of the third rectifier branch (430). [4] Charging device according to any of the preceding claims, wherein the first output terminals (414, 424, 434) of the three rectifier branches are connected to each other and the second output terminals (415, 425, 435) of the three rectifier branches are connected to each other. [5] Charging device according to any of the preceding claims, wherein each rectifier branch comprises two rectifier switching elements (411, 412, 421, 422, 431, 432), in particular semiconductor switching elements. [6] Charging device according to any one of the preceding claims, further comprising a control unit (350) configured to control the rectifier switching elements. [7] Charging device according to claim 6, wherein the control unit (350) is configured to detect whether alternating current is supplied by the OBC unit or the WPT unit, and to open the rectifier switching elements of the first rectifier branch when alternating current is supplied by the WPT unit, and to open the rectifier switching elements of the third rectifier branch when alternating current is supplied by the OBC unit. [8] Charging device according to claim 6 or 7, wherein the control unit (350) is configured to open the rectifier switching elements of the second rectifier branch when no alternating current is supplied by the WPT unit or the OBC unit. [9] Charging device according to any one of the preceding claims, wherein the OBC unit (320) and / or the WPT unit (310) are configured for bidirectional power transmission, and the control unit (350) is configured to control the rectifier switching elements according to the direction of power transmission. [10] Charging device according to a preceding claim, wherein the rectifier unit (500) comprises one or more further rectifier branches (510), wherein the second rectifier branch (420) and a further rectifier branch (510) are connected to a further AC power supply unit (520) and form a full-bridge rectifier configured to rectify the alternating current provided by the further AC power supply unit. [11] Charging device according to any of the preceding claims, further comprising a housing (370) in which the OBC unit (320) and the WPT unit (310) are jointly housed. [12] Electric vehicle comprising a traction battery (301) and a charging device (300) according to a preceding claim for charging the traction battery.

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