Charging device for a motor vehicle

Abstract

Loading device (22) for a motor vehicle (10), comprising: a plurality of plug-in connectors (12, 14, 16) for connecting the charging device (22) to at least one external electrical energy source (18, 20), a plurality of temperature measuring elements (26, 28, 30), each associated with one of the plug-in connection members (12, 14, 16) to detect a temperature of the plug-in connection members (12, 14, 16), and an evaluation unit (32) which is electrically connected to the temperature measuring elements (26, 28, 30) in order to evaluate the detected temperature of the temperature measuring elements (26, 28, 30), characterized in that the temperature measuring elements (26, 28, 30) are electrically connected to the evaluation unit (32) via a common first connecting line (42) and are further individually connected or connectable to the evaluation unit (32) via a second connecting line (36, 38, 40).

Description

The present invention relates to a charging device for a motor vehicle, having a plurality of plug-in connection members for connecting the charging device to at least one external electrical energy source, a plurality of temperature measuring elements, which are each assigned to one of the plug-in connection members, in order to detect a temperature of the plug-in connection members, and an evaluation unit, which is electrically connected to the temperature measuring elements in order to evaluate the detected temperature of the temperature measuring elements.The present invention further relates to a motor vehicle having an electric machine for providing drive power, an electrical energy store for storing electrical energy for the electric drive machine, and having a charging device for charging the electrical energy store.The present invention finally relates to a method for detecting a temperature of a plurality of plug-in connection elements of a charging device of a motor vehicle.Electrically driven motor vehicles usually have a plurality of charging boxes in order to connect the motor vehicle to external charging stations and to charge an internal electrical energy store. During a charging process, large amounts of electrical energy are usually transmitted via the charging cells, so that the charging cells can heat up during a charging process. To protect the load cells from overtemperatures and to protect them from damage caused by temperature, the load cells usually have temperature sensors which record the temperature of the load cells and correspondingly transmit it to a central control unit for controlling the charging process. The control unit can optionally interrupt the charging process if the temperature of the charging cells exceeds a threshold value. Such a charging device with temperature-monitored charging boxes is known, for example, from CN 1 03 138 316 A.DE 10 2011 010 227 A1 discloses a motor vehicle having at least one energy storage unit comprising a number of electrical cells, which energy storage unit is to be connected to an external energy source by means of a charging cable for charging, wherein the energy storage unit can be divided into at least two blocks, wherein at least one charging connection element is assigned to each block.DE 10 2012 200 523 A1 discloses a plug assembly operable to connect a vehicle wiring harness to a wall socket, the plug assembly comprising: a live plug contact configured to enable conduction of current from the wall socket to the vehicle charging system; a neutral plug contact configured to enable return of current from the vehicle charging system to the wall socket; a ground plug contact configured to enable connection of the vehicle charging system to ground; and a temperature sensor operable to sense a temperature at the wall socket.US 2015 / 0 171 568 A1 discloses further prior art.It is disadvantageous here that each individual temperature sensor is electrically connected separately via two electrical lines to an operational amplifier, so that the outlay for wiring the temperature sensors in the motor vehicle is great.It is therefore the object of the present invention to provide a charging device with temperature measuring elements for a motor vehicle, wherein the temperature measuring elements can be electrically connected to an evaluation unit with little technical complexity.This object is achieved in the charging device mentioned at the beginning in that the temperature measuring elements are connected to the evaluation unit via a common first connecting line and are individually electrically connected or connectable to the evaluation unit via a second connecting line.This object is achieved in the motor vehicle mentioned at the beginning by a charging device for charging the electrical energy store according to the present invention.This object is achieved in the method mentioned at the beginning for detecting a temperature of a plurality of plug-in connection elements of a charging device of a motor vehicle according to the present invention in that the temperature measuring elements are individually electrically connected sequentially to the evaluation unit in order to separately detect the respective temperature of the plug-in connectors.Because the temperature measuring elements are connected to the evaluation unit via a common first connecting line, the cabling outlay can be significantly reduced since the temperature measuring elements have only one individual electrical line for electrical contacting and are furthermore connected to the evaluation unit as a second electrical contact via the common electrical connection line.Because the temperature measuring elements are electrically connected sequentially individually to the evaluation unit according to the method according to the invention, a single evaluation unit can be used for evaluating the measurement signals of a plurality of temperature measuring elements, whereby the technical outlay is further reduced.The object of the present invention is thus completely achieved.In a preferred embodiment, the second connecting lines can each be connected to the evaluation unit via a controllable switch.As a result, the temperature measuring elements can be individually connected individually to the evaluation unit, so that an individual evaluation unit in the form of, for example, an operational amplifier can be used for all temperature measuring elements, so that the technical outlay is further reduced.It is particularly preferred here if the controllable switches are connected to a controller in order to open and close the controllable switches and to correspondingly selectively connect the temperature measuring elements to the evaluation unit.As a result, an offset current on the common first connecting line can be avoided, so that a precise measurement of the temperature is possible.In a preferred embodiment, the controller is designed to connect a temperature measuring element which is associated with a plug-in connection element connected to an external energy source to the evaluation unit.As a result, the temperature of the plug-in connection member used in each case can be detected, so that an overtemperature during charging via the plug-in connection member can be avoided.In a preferred embodiment, the temperature measuring elements can each be connected to an electrical connection of the evaluation unit via one of the controllable switches.As a result, a single evaluation unit can use for evaluating the temperature of different temperature measuring elements, so that the technical outlay is further reduced.In a preferred embodiment, the temperature measuring elements are designed as temperature measuring resistors.As a result, the temperature of the plug-in connection elements can be detected precisely with technically little outlay.It is furthermore preferred if the evaluation unit is designed as an operational amplifier.As a result, the detected temperature signal can be evaluated precisely by the temperature measuring elements.It is furthermore preferred if the plug-in connection elements are designed as load cells of the motor vehicle.This allows a secure and simple connection of the charging device to an external electrical energy source, such as a charging station.Overall, in the charging device according to the invention, the cabling outlay for the temperature measuring elements can be significantly reduced by the common first connecting line and the individual second connecting lines, since the temperature measuring elements each have only one individual lead and are connected or can be connected to the evaluation unit via a common return line.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.Exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. The following are shown: FIG. 1 shows a schematic illustration of a motor vehicle having a charging device for charging an electrical energy store; FIG. 2 shows a schematic illustration of a circuit for electrically connecting various temperature measuring elements to an evaluation unit; FIG. 3 shows a further embodiment of the circuit for connecting the temperature measuring elements to an evaluation unit; FIG. 4 shows a flow diagram of a method for determining a temperature of a charging socket of a motor vehicle used.In FIG. 1, a motor vehicle is illustrated in a schematic plan view and is denoted generally by 10. The motor vehicle 10 can be designed as a purely electrically driven vehicle or as a motor vehicle with a hybrid drive and generally has three plug-in connection elements 12, 14, 16 designed as electrical charging boxes in order to generally connect the motor vehicle 10 electrically to one or a plurality of electrical energy sources 18, 20 and accordingly supply electrical loads and / or electrical energy stores with electrical energy.The plug-in connection elements 12, 14, 16 designed as charging receptacles are electrically connected to a charging unit 22, wherein the charging unit 22 is electrically connected to an electrical energy store 24 of the motor vehicle 10 in order to charge the electrical energy store 24.The charging unit 22 serves to forward an electrical voltage and in particular an electrical high voltage from the external electrical energy sources 18, 20 to the electrical energy store 24 and, if appropriate, to convert the voltage into a charging voltage.A temperature sensor 26, 28, 30 is assigned to each of the plug-in connection elements 12, 14, 16 designed as load cells in order to detect the temperature of the respective plug-in connection element 12, 14, 16 designed as load cell in order to avoid over temperatures during the electrical energy transmission via the plug-in connection elements 12, 14, 16 designed as load cells. The temperature sensors 26, 28, 30 are generally electrically connected to an evaluation unit 32 in order to evaluate the temperature signals from the temperature sensors 26, 28, 30 and to control the charging process accordingly.The temperature sensors 26, 28, 30 are generally each connected to the evaluation unit 32 via an individual electrical line, wherein all temperature sensors 26, 28, 30 are connected to the evaluation unit 32 via a common return line, as is explained in more detail below. As a result, the technical outlay for electrically connecting the temperature sensors 26, 28, 30 to the evaluation unit 32 can be reduced.FIG. 2 shows a first embodiment of an electrical circuit of the evaluation unit 32 and of the temperature sensors 26, 28, 30 connected thereto.The temperature sensors 26, 28, 30 are designed as temperature measuring resistors in this embodiment. The evaluation unit 32 has three operational amplifiers 34, 37, 39, wherein a first electrical connection of the operational amplifiers 34, 37, 39 is connected to the temperature sensors 26, 28, 30 via an individual electrical connecting line 36, 38, 40, respectively. The temperature sensors 26, 28, 30 are connected via a common electrical connecting line 42 to a second electrical terminal of the operational amplifiers 34, 37, 39. The technical outlay for wiring the temperature sensors 26, 28, 30 can be reduced by the electrical contacting of the temperature sensors 26, 28, 30 configured in this way, since the common electrical connecting line 42 is used as a return line for connecting the temperature sensors 26, 28, 30 to the operational amplifiers 34, 37, 39.FIG. 3 shows a further embodiment of a circuit of the evaluation unit 32 and of the temperature sensors 26, 28, 30 connected thereto.In this embodiment, the evaluation unit 32 has only one operational amplifier 44, the first input terminal of which can be connected to the temperature sensors 26, 28, 30 via the individual electrical connecting line 36, 38, 40. The electrical connecting lines 36, 38, 40 each have a controllable switch 46, 48, 50 for individually electrically connecting the temperature sensors 26, 28, 30 to the first input terminal of the operational amplifier 44. The temperature sensors 26, 28, 30 are connected to a second input terminal of the operational amplifier 44 via the common electrical connection line 42. The evaluation unit 32 further comprises a controller 52 connected to the controllable switches 46, 48, 50 for sequentially opening and closing the controllable switches 46, 48, 50 and electrically connecting the temperature sensors 26, 28, 30 individually and successively to the operational amplifier 44. The controller 52 is preferably designed as a microcontroller.By individually connecting the temperature sensors 26, 28, 30 via the controllable switches 46, 48, 50, the temperature measurement values of the temperature sensors 26, 28, 30 can be read out or evaluated in a time-shifted manner by means of an individual operational amplifier 44, so that the technical outlay of the evaluation unit 32 is reduced.The controllable switches 46, 48, 50 also serve to avoid an offset current on the common electrical connecting line 42. As a result, the measurement signal of the temperature sensors 26, 28, 30 can be detected precisely and is not influenced by the offset current.By means of a sequential time-shifted electrical connection of a respective temperature sensor 26, 28, 30 to the operational amplifier 44, all temperature measurement signals can be read out one after the other, so that the temperature of the plug connection elements 12, 14, 16 designed as load cells can be detected one after the other and regularly and a reliable temperature measurement of the plug connection elements 12, 14, 16 designed as load cells is possible. If only one of the plug-in connection elements 12, 14, 16 designed as charging receptacles is electrically connected to an external electrical energy source 18, 20 for charging the electrical energy store 24, only the correspondingly assigned temperature sensor 26, 28, 30 can be connected to the operational amplifier 44 in each case, so that in this case only the charging receptacle used is monitored.FIG. 4 schematically shows a schematic flow diagram for explaining the reading out of a measured value of the temperature sensors 26, 28, 30. The process is generally designated 60. The method begins with step 62. At step 64, a self-test of the controllable switches 46, 48, 50 is first carried out. In step 66, the evaluation unit 32 queries which of the plug-in connection elements 12, 14, 16 designed as charging receptacles is connected for charging the electrical energy store 24. In step 68, it is queried whether a first plug connection element 12 designed as a charging socket is in operation, and if the first plug connection element 12 designed as a charging socket is in operation, the controllable switch 46 is activated in step 70 and the measured value of the temperature sensor 26 is read out in step 72.If the first plug-in connection element 12 designed as a charging socket is not in operation, it is queried in step 74 whether the second plug-in connection element 14 designed as a charging socket is in operation and if the second plug-in connection element 14 designed as a charging socket is in operation, the controllable switch 48 is activated or closed in step 76 and the measured value of the temperature sensor 28 is read out in step 78.If it is determined in step 74 that the second plug connector element 14 designed as a charging socket is not in operation, it is queried in step 80 whether the third plug connector element 16 designed as a charging socket is in operation and if the third plug connector element 16 designed as a charging socket is in operation, the controllable switch 50 is closed in step 82 and the temperature measurement value of the temperature sensor 30 is read out in step 84. If none of the load cells 12, 14, 16 are connected, the method 60 returns to step 66, as shown by feedback 86. This query can be made regularly, for example once per second.The method enables the controllable switches 46, 48, 50 to be closed in a targeted manner in order to read out a specific one of the temperature sensors 26, 28, 30 and to measure the temperature of the plug-in connection elements 12, 14, 16 which are correspondingly in operation and are designed as a charging socket.In a preferred embodiment, the evaluation unit 32 is designed to calculate an electrical charging power transmitted via the plug connector 12, 14, 16 via the detected temperature of the plug connector 12, 14, 16 used. As a result, the electrical charging power can be limited and damage to the electrical components can be avoided.

Claims

Charging device (22) for a motor vehicle (10), having: a plurality of plug-in connection members (12, 14, 16) for connecting the charging device (22) to at least one external electrical energy source (18, 20), a plurality of temperature measuring elements (26, 28, 30) which are each assigned to one of the plug-in connection members (12, 14, 16) in order to record a temperature of the plug-in connection members (12, 14, 16), and an evaluation unit (32) which is electrically connected to the temperature measuring elements (26, 28, 30) in order to evaluate the recorded temperature of the temperature measuring elements (26, 28, 30), characterized in that the temperature measuring elements (26, 28, 30) are electrically connected to the evaluation unit (32) via a common first connecting line (42) and are furthermore electrically connected or can be electrically connected individually to the evaluation unit (32) in each case via a second connecting line (36, 38, 40).Charging device according to Claim 1, characterized in that the second connecting lines (36, 38, 40) can each be connected to the evaluation unit (32) via a controllable switch (46, 48, 50).Charging device according to claim 2, characterised in that the controllable switches (46, 48, 50) are connected to a controller (52) in order to open and close the controllable switches (46, 48, 50) and to correspondingly selectively connect the temperature measuring elements (26, 28, 30) to the evaluation unit (32).Charging device according to Claim 3, characterized in that the controller (52) is designed to connect a temperature measuring element (26, 28, 30) to the evaluation unit (32), which is assigned to a plug-in connection member (12, 14, 16) connected to an external energy source (18, 20).Charging device according to one of Claims 2 to 4, characterized in that the temperature measuring elements (26, 28, 30) can each be connected to an electrical connection of the evaluation unit (32) via one of the controllable switches (46, 48, 50).Charging device according to one of Claims 1 to 5, characterized in that the temperature measuring elements (26, 28, 30) are designed as temperature measuring resistors.Charging device according to one of Claims 1 to 6, characterized in that the evaluation unit (32) is designed as an operational amplifier.Charging device according to one of Claims 1 to 7, characterized in that the plug-in connection elements (12, 14, 16) are designed as charging boxes.Motor vehicle (10) having an electric machine for providing drive power, an electrical energy store (24) for storing electrical energy for the electric drive machine and having a charging device (22) according to one of Claims 1 to 8, for charging the electrical energy store (24).Method (60) for detecting a temperature of a plurality of plug-in connection elements (12, 14, 16) of a charging device (22) of a motor vehicle (10) according to one of Claims 1 to 8, wherein the temperature measurement elements (26, 28, 30) are individually electrically connected sequentially to the evaluation unit (32) in order to separately detect the respective temperature of the plug-in connection elements (12, 14, 16).

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