electric vehicle

Abstract

Electric vehicle, comprising a traction battery (12), a charger (20) which has at least one energy storage component (22, 24, 26), a battery interface (30) and a charging interface (32) for coupling to an external source, wherein the battery interface (30) is connected via a first electrical line (301) to a positive terminal of the traction battery (12) and via a second line (302) to the negative terminal of the traction battery (12), wherein a protective device (50) is provided to protect a person from electric shock in the event of accidental damage to the charger (20), the traction battery (12) and / or the electrical lines (301, 302), wherein the protective device (50) comprises a diode (52) and a switching device (54) and / or a discharge circuit (60).

Description

[0001] The invention relates to an electric vehicle with a traction battery, a charger which has a battery interface and a charging interface for coupling to an external source, wherein the battery interface is connected to a positive terminal of the traction battery via a first electrical line and to the negative terminal of the traction battery via a second line.

[0002] An electric vehicle typically has an electric drive unit to power the vehicle's wheels and a traction battery to supply the electric drive unit with electrical energy during operation. The traction battery can be charged using either alternating current (AC) or direct current (DC) at a charging port on the electric vehicle. However, the traction battery can only be charged with DC, so a charger is connected to it. The charger converts AC to DC.

[0003] In an accident, the charger and other live components can be damaged, posing a risk of electric shock to a person from exposed electrical components. Therefore, efforts are usually made to position the charger and other live components in a crash-resistant area of ​​the electric vehicle, thereby reducing the risk of damage to the charger and other components. This is intended to reduce the risk of electric shock.

[0004] Positioning the charger in such a crash-safe area increases the effort required to design the electric vehicle and may not be possible at all.

[0005] From WO 2020 / 070164 A1 and DE 10 2015 223 230 A1, a vehicle-side charging system for inductively charging a motor vehicle battery is known, wherein the charging system according to WO 2020 / 070164 A1 has a discharge arrangement with an ohmic resistor and a transistor, and the charging system according to DE 10 2015 223 230 A1 has two battery protection switches arranged between an inverter and a battery.

[0006] Furthermore, DE 10 2021 205 802 A1 discloses a device for electrically connecting a fuel cell stack and a high-voltage battery for supplying electrical energy to consumers which are connected on the side of the high-voltage battery, wherein the fuel cell stack and the high-voltage battery are connected to each other via a diode that blocks a current flow in the direction of the fuel cell stack and a switch for closing and disconnecting the connection.

[0007] The object of the invention is to provide an electric vehicle in which the risk to a person of electric shock in the event of an accident and damage to the charger, the traction battery and / or an electrical line connecting the charger to the traction battery is reduced in a simple and reliable manner.

[0008] The problem is solved by the features of claim 1.

[0009] The electric vehicle includes a protective device to reduce the risk of electric shock to a person in the event of accidental damage to the charger, traction battery, and / or electrical wiring. In an accident, the charger, traction battery, and / or the electrical wiring connecting the traction battery to the charger may be damaged in such a way that a conductive element is exposed and would cause an electric shock upon contact. Alternatively, the conductive component may be damaged in such a way that it is electrically connected to another component accessible to the person, such as the vehicle body, and would therefore pose a risk of electric shock upon contact with the other component.

[0010] According to the invention, the protective device comprises a diode and a switching device and / or a discharge device. In other words, the protective device necessarily comprises a diode and additionally a switching device and / or a discharge device.

[0011] The diode is located on the first electrical conductor connected to the positive terminal of the traction battery. A diode inherently has a forward direction and a reverse direction. In this case, the diode is configured to allow current to flow from the charger to the positive terminal of the traction battery. Therefore, the current flow is from the charger to the positive terminal of the traction battery. In the opposite direction, the diode blocks the current flow, thus preventing current from flowing from the positive terminal of the traction battery to the charger.

[0012] The diode installed on the first electrical conductor prevents an electric current from flowing from the traction battery through the diode in the event of a short circuit between the two conductors, or between the positive and negative terminals of the traction battery, caused by an accident. This prevents an electric shock to anyone touching the conductors. It is crucial that the electric current in the traction battery flows exclusively from the positive to the negative terminal.

[0013] The switch device is designed such that in a closed position of the switch device at least one energy-storing component of the charger is electrically connected to the battery interface and in an open position of the switch device the energy-storing component of the charger is disconnected from the battery interface.

[0014] The switching device is arranged between a battery interface and the other components of the charger and comprises two switching elements, a first switching element being arranged at a first connection and a second switching element being arranged at a second connection. The switching elements are preferably designed as electronic or mechanical switching elements.

[0015] The charger has at least one energy storage component, in particular a capacitor, which stores electrical energy during the charging process of the traction battery and serves, for example, to smooth direct current converted from alternating current. After the charging process and decoupling of the charging interface from the power grid, electrical energy remains stored in the energy storage component, which could pose a risk of electric shock if the charger, in particular the battery interface, and / or the electrical wiring is damaged.

[0016] Because the switching device, i.e., the two switching elements, is in an open position when not charging, for example, when the electric vehicle is being driven, the battery interface and the electrical wiring on the charger side are decoupled from the energy storage components. Only during a charging process are the switching device, i.e., the switching elements, switched to the closed position, thus enabling charging. The switching device is only switched to the closed position for the purpose of charging the battery.

[0017] The discharge device has a consumer element and a switching element adjustable between a closed position and an open position, wherein the discharge device is designed such that in the closed position of the switching element the consumer element is electrically connected to the energy-storing component in such a way that the energy-storing component discharges.

[0018] As explained in a previous paragraph, the at least one energy storage component stores electrical energy during a charging process of the traction battery, whereby after the charging process and decoupling of the charging interface from the power grid, electrical energy continues to be stored in the energy storage component, which would pose a risk of electric shock in the event of damage to the charger, in particular the battery interface, and / or the electrical lines.

[0019] The discharge device allows the energy storage component to be discharged as needed, with a load element being selectively activated via a switching element. This switching element is normally open, i.e., in the open position. After the traction battery has been charged, the switching element is selectively moved to the closed position, thus electrically coupling the energy storage component with the load element and thereby discharging the energy storage component. The load element is, in particular, a resistor. This prevents electrical energy from being stored in the energy storage component during operation.

[0020] Such a protective device uses multiple protective mechanisms to prevent a person from being injured by electric shock in the event of an accident and damage to the traction battery, charger, and / or electrical wiring, with at least one protective mechanism provided on both the charger and battery sides. A redundant safety system could even be in place on the charger side if a switch and a discharge device are present.

[0021] Preferably, the charger has three capacitors, one of which is arranged on a first line connecting two electrical connections of the charger, and the other two capacitors are arranged on a second line connecting two electrical connections of the charger, the second line being connected to ground. The capacitors serve to smooth a direct current converted from alternating current.

[0022] Preferably, the charger has line electronics for AC-DC conversion, whereby a charging current present as alternating current can be converted into an alternating current required for charging the traction battery.

[0023] In a preferred embodiment, the charger is connected via the charging interface to a secondary unit of an inductive charging device, wherein the secondary unit can be connected to an external primary unit. The primary unit is electrically coupled to a power supply network and is configured such that a magnetic charging field is generated by means of a primary coil, which is designed to induce a charging current in a secondary coil of the secondary unit. The charging current is then routed via the charger to the traction battery, thereby charging the traction battery.

[0024] An embodiment of the invention is explained in more detail with reference to the drawings. Fig. Figure 1 schematically shows an electric vehicle and an inductive charging device, and Fig. Figure 2 schematically shows a charger and a traction battery of the electric vehicle. Fig. 1.

[0025] Fig. Figure 1 shows an electric vehicle 10, which has a traction battery 12 and a [missing information] in the Fig. The electric vehicle 10 has an electric traction motor (not shown), which is supplied with electrical energy by the traction battery 12. The traction battery 12 discharges during operation of the electric vehicle 10, i.e., due to the supply of electrical energy to the traction motor by the traction battery 12, and must be recharged periodically. In this process, the traction battery 12 is electrically connected to a public power grid, whereby the connection can be either conductive, i.e., via a charging cable, or inductive, i.e., wireless. Fig. Figure 1 shows an inductive coupling. For this purpose, an inductive charging device 40 is provided. The inductive charging device 40 comprises a primary unit 42 arranged on a road surface with a primary coil and a secondary unit 44 arranged on the underbody of the electric vehicle 10 with a secondary coil 46. The primary unit 42 is electrically coupled to the power supply network, whereby a magnetic charging field is generated by the primary unit 42, i.e., by the primary coil. The magnetic charging field induces a charging current in a secondary coil of the secondary unit 44. The charging current is in the form of alternating current, which is converted into direct current required for charging the traction battery 12 by a charger 20, which is connected between the secondary unit 44 and the traction battery 12.

[0026] Fig.Figure 2 shows the secondary unit 44 of the inductive charging device 40, the charger 20 and the traction battery 12.

[0027] The charger 20 is electrically connected to the secondary unit 44 of the inductive charging device 40 via a charging interface 32 and to the traction battery 12 via a battery interface 30. The induced charging current, which is alternating current, is transmitted to the charger 20 via the charging interface 32. A direct current is transmitted to the traction battery 12 via the battery interface 30, which is connected to the positive terminal HV+ of the traction battery 12 via a first electrical line 301 and to the negative terminal HV- of the traction battery 12 via a second line 302.

[0028] The charger 20 has power electronics 21, which are connected to the charging interface 32 on the charger side and convert alternating current to direct current in a generally known manner. The power electronics are also connected to the battery interface 30 via two electrical connections 211, 212.

[0029] Furthermore, the charger 20 comprises three energy-storing components 22, 24, 26, in particular three capacitors, wherein one of the capacitors 22 is arranged on a first line 23 connecting the two electrical connections 211, 212, and the other two capacitors 24, 26 are arranged on a second line 27 connecting the two electrical connections 211, 212. The second line 27 is connected to an earth 29.

[0030] The capacitors, i.e., the energy-storing components 22, 24, 26, serve in particular to smooth the direct current converted from alternating current. During a charging process of the traction battery 12, the energy-storing components 22, 24, 26, in this case the capacitors, are charged with electrical energy. After the charging process, and especially during operation of the electric vehicle 10, electrical energy remains stored in the energy-storing components 22, 24, 26. This would pose a risk of electric shock if the charger 20, in particular the battery interface 30, and / or the electrical lines 301, 302, were damaged. The traction battery 12 also presents a further risk of electric shock if damaged.

[0031] To reduce the risk of electric shock to a person, the electric vehicle 10 has a protective device 50.

[0032] The protective device 50 comprises a diode 52, a switching device 54 and a discharge device 60.

[0033] The diode 52 is arranged on the first electrical conductor 301, which is connected to the positive terminal HV+ of the traction battery 12. The diode 52 is configured such that it allows current to flow from the charger 20 to the positive terminal HV+ of the traction battery 12, while blocking current flow from the positive terminal HV+ of the traction battery 12 to the charger 20. This prevents an electric current from flowing through the diode 52 in the event of a short circuit between the two conductors 301 and 302, or between the positive terminal HV+ and the negative terminal HV- of the traction battery 12, thus preventing an electric shock to a person touching the conductors 301 and 302. This reduces the risk of electric shock from the battery.

[0034] The switching device 54 has two switching elements 56, 58, wherein a first switching element 56 is arranged at a first connection 211 and a second switching element 58 is arranged at a second connection 212. The switching device 54 is designed such that in a closed position of the switching elements 56, 58, which are always moved together between positions, the energy storage components 22, 24, 26 are electrically connected to the battery interface 30, and in an open position of the switching elements 56, 58, the energy storage components 22, 24, 26 are disconnected from the battery interface 30.

[0035] To reduce the risk of electric shock, the two switching elements 56, 58 are permanently in the open position when not charging, for example, when the electric vehicle 10 is in operation. This decouples the battery interface 30 and the electrical lines 301, 302 from the energy storage components 22, 24, 26 on the charger side. Only when charging begins are the switching elements 56, 58 switched to the closed position, thus enabling charging. This reduces the risk of electric shock on the charger side.

[0036] The discharge device 60 comprises a consumer element 62 and a switching element 64 adjustable between a closed and an open position. The consumer element 62 and the switching element 64 are arranged on a further line 61 connecting the two electrical connections 211, 212. The consumer element 62 is designed as a resistor.

[0037] The discharge device 60 is designed such that the switching element 64 is generally in the open position and is only moved to the closed position for a certain period of time after a charging process. In the closed position of the switching element 64, the consumer element 62 is electrically connected to the energy-storing components 22, 24, 26 (i.e., the capacitors) in such a way that the energy-storing components 22, 24, 26 discharge. This allows the energy-storing components 22, 24, 26, which were charged during the charging process, to be discharged as needed, so that no electrical energy is stored in the energy-storing components 22, 24, 26 during driving operation.

[0038] Such a protective device 50, through several protective mechanisms, prevents a person from being injured by electric shock in the event of an accident and damage to the traction battery 12, the charger 20 and / or the electrical lines 301, 302, wherein at least one protective mechanism is provided on both the charger side and the battery side.

Claims

[1] Electric vehicle, with a traction battery (12), a charger (20) having at least one energy-storing component (22, 24, 26), a battery interface (30) and a charging interface (32) for coupling to an external source, wherein the battery interface (30) is connected via a first electrical line (301) to a positive pole of the traction battery (12) and via a second line (302) to the negative pole of the traction battery (12), wherein a protective device (50) is provided for protecting a person from an electric shock in the event of accidental damage to the charger (20), the traction battery (12) and / or the electrical lines (301, 302), wherein the protective device (50) has a diode (52) and a switch device (54) and / or a discharge circuit (60), wherein the diode (52) is arranged on the first electrical line (301) and is designed such that a current flow from the traction battery (12) is blocked in the event of a short circuit between the two lines (301, 302), wherein the switch device (54) is interposed between the energy-storing component (22, 24, 26) and the battery interface (30) and is designed such that in a closed position of the switch device (54), the at least one energy-storing component (22, 24,26) of the charger (20) is electrically connected to the battery interface (30) and in an open position of the switch device (54) the energy-storing component (22, 24, 26) of the charger (20) is electrically separated from the battery interface (30), such that the switch device (54) is switched to the open position during a non-charging process and the switch device (54) is switched to the closed position during a charging process, and wherein the discharging device (60) has a consumer element (62) and a switching element (64) which can be adjusted between a closed position and an open position, wherein the discharging device (60) is designed such that in the closed position of the switching element (64) the consumer element (62) is electrically connected to the energy-storing component (22, 24, 26) in such a way that the energy-storing component (22, 24, 26) is discharged, wherein after a charging process of the traction battery (12) the switching element (64) is adjusted to the closed position and a discharge of the energy-storing component (22, 24, 26) takes place in such a way that no electrical energy is stored in the energy-storing component (22, 24, 26) during driving operation. [2] Electric vehicle according to claim 1, characterized by that the at least one energy-storing component (20, 22, 24) is a capacitor. [3] Electric vehicle according to claim 2, characterized bythat the charger (20) has three capacitors, wherein one of the capacitors is arranged on a first line (23) connecting two electrical connections (211, 212) of the charger (20), and the other two capacitors are arranged on a second line (27) connecting the two electrical connections (211, 212) of the charger (20), wherein the second line (27) is connected to an earth (29). [4] Electric vehicle according to one of the preceding claims, characterized by that the charger (20) has power electronics (21) serving for AC-DC conversion. [5] Electric vehicle according to one of the preceding claims, characterized by that the charger (20) is connected via the charging interface (32) to a secondary unit (44) of an inductive charging device (40), wherein the secondary unit (44) is connectable to an external primary unit (42). [6] Electric vehicle according to one of the preceding claims, characterized by that the switch device (54) has two switch elements (56, 58), wherein a first switch element (56) is arranged on a first connection (211) and a second switch element (58) is arranged on a second connection (212). [7] Electric vehicle according to claim 6, characterized by that the switching elements (56, 58) are designed as electronic or mechanical switching elements.

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