Charging connectors for electric and hybrid vehicles

Abstract

System comprising a charging connector (1) for electric and hybrid vehicles and a control unit (10), wherein the charging connector (1) is provided with a housing (7) and AC charging contacts (2), DC charging contacts (9) and temperature sensors (3) arranged in the housing (7), wherein at least one temperature sensor (12) provided with a thermal connection area (11) for measuring the temperature of the DC charging contacts (9) is arranged on the DC charging contacts (9) and the terminals (15) of the temperature sensor (12) are brought out of the housing (7), wherein a temperature sensor (3) provided with a thermal connection area (4) for measuring the temperature of the respective AC charging contact (2) is arranged on each AC charging contact (2), the temperature sensors (3) are connected in series, and the two terminals (6) of the series connection are brought out of the housing (7).The terminals (6) leading out of the housing (7) are connected to the control unit (10) for receiving the signal from the temperature sensors (3) connected in series, and the control unit (10) is configured to determine the functionality of the temperature sensors (3) connected in series and to control the charging current as a function of the temperature measured by the temperature sensors (3), whereby the charging process is not interrupted when a limit temperature is reached, but rather the charging current is throttled as the limit temperature is approached, so that the charging process does not have to be interrupted, but continues continuously.

Description

The invention relates to a system comprising a charging connector for electric and hybrid vehicles and a control unit, and a method for operating a system comprising a charging connector for electric and hybrid vehicles and a control unit. Electric and hybrid vehicles have a rechargeable energy storage system, usually a high-voltage battery, which provides energy to an electric drive motor during operation. The storage capacity of these high-voltage batteries is limited, so they must be recharged regularly at a charging station. The battery is charged via a charging cable located between the charging station and the vehicle. This charging cable, for example according to the European standard IEC 62196 Type 2, has a charging plug on one end that can be inserted into a charging socket provided at the charging station, and a charging coupler on the other end that can be connected to a charging connector installed in the electric or hybrid vehicle. For the purposes of this document, charging sockets, charging plugs, charging couplers, and charging connectors are collectively referred to as "charging connectors."Charging sockets and charging couplings have contact sleeves as charging contacts, and charging plugs as well as charging plugs that can be installed in electric and hybrid vehicles have contact pins as charging contacts which can be inserted into the contact sleeves. The contacts between a charging plug and a charging socket are subject to increased surface wear due to frequent use and repeated plugging and unplugging. This wear leads to an increase in contact resistance, which can cause significant heat generation during the charging process. Charging connectors for electric and hybrid vehicles are subject to legal and user-specific requirements regarding temperature monitoring of AC and DC charging contacts. For DC charging, temperature measurement at both DC charging contacts is generally required. For this purpose, a suitable temperature-measuring component, usually an NTC resistor, is placed as close as possible to the heat source, i.e., the charging contact, to enable real-time temperature monitoring for charging optimization and safety monitoring.An NTC resistor is a resistor used in electronic components. It is also known as a thermistor or negative temperature coefficient resistor. The abbreviation "NTC" stands for "negative temperature coefficient" and describes the property of thermistors to conduct electricity better with increasing temperature, as they exhibit a negative temperature coefficient. Furthermore, PTC resistors are known. A PTC resistor, also called a positive temperature coefficient (PTC) thermistor, is also a temperature-dependent resistor, but it conducts electricity better at low temperatures than at high temperatures. Some PTC resistors exhibit an almost linear characteristic curve (resistance as a function of temperature). However, there are also PTC resistors that behave non-linearly, with a sharp increase in resistance near their rated operating temperature. Such PTC elements can thus serve as a kind of "fuse" by returning a rapidly changing value to a reading system when the critical temperature has been exceeded. Temperature monitoring may also be required for AC charging contacts. Depending on the standard and manufacturer's specifications, either actual temperature measurement or simply detection of exceeding a temperature threshold is necessary. This can be required either separately for each AC charging contact (e.g., L1, L2, L3, and N in connectors according to the European standard IEC 62196 Type 2) or collectively for all AC charging contacts. DE 10 2015 106 251 A1 describes a temperature monitoring device with a carrier element extending along a plane and having at least one opening. The carrier element can be designed as a printed circuit board. The contact elements are components of a contact assembly that can be attached to the connector insert as a modular unit. The contact assembly includes a temperature monitoring device with a carrier element. The temperature monitoring device serves to detect any impermissible heating of at least those contact elements that are used to transmit high currents during operation of the connector part. For the necessary contact, the carrier element has a metallic coating at each opening to provide a contact surface in the form of a via. WO 2021 / 004 765 A1 describes an electrical assembly with a temperature monitoring device. This assembly includes a connector with both AC and DC charging pins. To monitor potential heating, particularly at the DC charging pins, the connector incorporates an electrical assembly. This assembly consists of contact elements mounted on a carrier element and electrically connected to associated load lines. Each contact element is inserted into a corresponding recess in the carrier element. According to DE 10 2014 111 831 A1, a connector part for connecting to a mating connector part comprises several electrical contact elements for conducting an electric current and establishing an electrical contact with contact elements of a mating connector part. Several temperature sensors are provided, each arranged on an associated contact element to detect a temperature change at the associated contact element, with the temperature sensors being connected to a common sensor line. In this way, a connector part is provided that enables simple and cost-effective temperature monitoring with fast response and a simple design. From DE 20 2016 103 030 U1, a connector is known which is connected to a charging cable, in particular to a vehicle charging cable of an electric or hybrid vehicle, and comprises a connector housing, as well as live current contacts for a charging current, in particular a battery of the electric or hybrid vehicle, wherein at least one temperature sensor for charge control and / or charge monitoring is arranged in the connector housing, wherein the temperature sensor consists of a sensor head and sensor connection legs, wherein the sensor head is in direct contact with an area of ​​a live plug contact and the connection legs are arranged parallel to the live plug contact, and that the sensor head is held in the area of ​​the corresponding live plug contact by a heat shrink tube and is pressed against the area of ​​the live plug contact by a shrinking process.wherein the heat shrink tubing completely surrounds the area of ​​the plug contact and the sensor head, so that the temperature sensor is thermally and mechanically connected to the plug contact via the heat shrink tubing, and the temperature sensor is arranged in a kind of heat chamber formed by the heat shrink tubing. DE 10 2014 012 576 A1 describes a device for conducting electrical energy by means of an electrical conductor surrounded by at least one electrically insulating second layer, and with at least one temperature sensor for detecting the temperature of the electrical conductor, wherein the temperature sensor is arranged between the electrical conductor and the electrically insulating second layer. This solution is characterized in that an electrically insulating and thermally conductive first layer is located in the space between the electrically insulating second layer and the electrical conductor, and that the temperature sensor is arranged in the region of this electrically insulating and thermally conductive first layer. Based on this, the object of the present invention is to make the communication between a charging connector for an electric or hybrid vehicle and an external device simple and efficient. This problem is solved by the subject matter of the independent claims. Preferred embodiments of the invention are described in the dependent claims. The basic idea of ​​the invention is that various sensor data can be transmitted via two connections through temperature sensors connected in series, where "connected in series" refers to the galvanic contact of one temperature sensor with the next, and so on, up to one of the two connections. This allows the use of receiver units that are also equipped with two connection options. The transmitted temperature thus corresponds to an average temperature of all temperature sensors. Since each AC charging contact has a thermal connection area and a temperature sensor attached to it, temperature monitoring is implemented in the immediate vicinity of the AC charging contacts, resulting in a significantly improved response time. Regarding the charging connector according to the invention, it should be noted that it is designed to be plugged into a corresponding charging connector. When a corresponding charging connector is mentioned here, this refers, on the one hand, to a charging connector that has the same mating face as the charging connector according to the invention, but where one mating face has contact pins and the other mating face has contact sleeves, and vice versa. The set consisting of the charging connector according to the invention and the corresponding charging connector can therefore be plugged together. On the other hand, the term "corresponding charging connector" is also used here when the mating faces only partially correspond in the aforementioned sense, i.e., the corresponding charging connector, for example,The charging connector according to the invention does not have all the contacts present in the charging connector according to the invention, but the existing contacts of the corresponding charging connector correspond to those of the charging connector according to the invention in terms of their mating face, so that the charging connector according to the invention and the corresponding charging connector can also be plugged together in this case. Such a case exists, for example, with a charging coupler for DC charging connected to a charging cable according to the European standard IEC 62196 Type 2. Such a charging coupler can be plugged into a charging plug installed in the body of an electric or hybrid vehicle and suitable for AC charging as well as for DC charging, wherein in the AC mating face of the DC charging coupler only the communication contacts and the protective contact are present, but no contacts for live conductors and a neutral conductor for AC charging. In principle, temperature sensors can be designed in various ways. However, according to a preferred embodiment of the invention, the temperature sensors are linear temperature sensors. A linear temperature sensor, as used here, is understood to be a temperature sensor that exhibits a substantially linear temperature-resistance curve, at least within a temperature range, with resistance increasing substantially linearly as a function of increasing temperature. According to a preferred embodiment of the invention, the linear temperature sensors are PTC elements. There are essentially two different types of PTC elements, which exhibit different resistance profiles. In this embodiment, PTC elements with a substantially linear resistance profile are used to determine the temperature of the AC charging contacts based on their resistances. The series connection of linear PTC elements means that the temperature-dependent resistances of the PTC elements are connected one after the other and thus add up. This allows for the determination of both the sum of all measured temperatures and the average temperature of all AC charging contacts equipped with temperature sensors. The temperature sensors and connections can be arranged in the housing in various ways. However, according to a preferred embodiment of the invention, the temperature sensors and the two connections of the series circuit are arranged on a printed circuit board. According to a preferred embodiment of the invention, the thermal connection areas are provided with thermal contact elements with which a respective charging contact can be thermally connected. By arranging thermal contact elements in the thermal connection areas, the heat generated at the AC charging contacts is transferred to the thermal contact elements via direct thermal conduction, excluding convection. According to a further preferred embodiment of the invention, the thermal contact elements are non-galvanically conductive. This makes it possible to thermally couple the AC charging contacts directly to the temperature sensors via the thermal contact elements, so that the heat generated at the AC charging contacts can be transferred almost instantaneously, which in turn contributes to a rapid temperature measurement. The control unit can now be designed in such a way that, when the charging connectors are plugged in, it allows communication to and / or from the corresponding charging connector. In this way, communication between a charging station and an electric or hybrid vehicle connected to the charging station via a charging cable is possible. The control unit can, in principle, be located inside the housing. However, this is not mandatory. Therefore, the control unit can be located either inside or outside the housing. Locating the control unit outside the housing can be particularly advantageous if the charging connector is a built-in charging plug attached to the body of an electric or hybrid vehicle. In this case, there is usually sufficient space available inside the body to install the control unit without it interfering with or obstructing other components. The control unit can measure the resistance of the temperature sensors arranged in series. Furthermore, the control unit is designed to determine a corresponding measured temperature based on this resistance. Knowing the number of temperature sensors used allows the control unit to determine not only the sum of the measured temperatures, but also the average temperature and the temperature profile. This enables the control unit to draw conclusions about the functionality of the sensors. The measured resistance should always be higher than the resistance corresponding to a predefined minimum temperature. Conversely, a functional defect in one of the temperature sensors can also be identified if the resistance exceeds a predefined maximum temperature. In principle, various analysis methods can be implemented in the control unit. However, according to a preferred embodiment of the invention, the control unit is further configured to determine the functionality of the series-connected temperature sensors by means of gradient monitoring. Gradient monitoring detects abrupt increases and decreases in temperature, which are an indication of a malfunctioning temperature sensor. According to a preferred embodiment of the invention, the control unit is configured to monitor the functionality of the charging electronics used for the charging process. Detecting faulty charging electronics allows the charging process to be terminated prematurely. According to the invention, the control unit is configured to regulate the charging current based on the temperature measured by the temperature sensors. This means that the charging process is not interrupted when a limit temperature is reached. Instead, as this limit temperature is approached, the charging current is throttled so that the charging process does not have to be interrupted but continues continuously. According to the invention, DC charging contacts are provided in the housing, wherein at least one temperature sensor with a thermal connection area is arranged on the DC charging contacts for measuring the temperature of the DC charging contacts and the connections of the temperature sensor are led out of the housing. In this context, such contacts are referred to as DC charging contacts, which are exclusively designed for charging with direct current. These DC charging contacts heat up considerably when charging with high currents. In contrast to DC contacts, there are AC charging contacts. These refer to the live conductors and the neutral conductor (center conductor), which are also designed for charging with alternating current. A live conductor (also commonly referred to as a phase) is a conductor that is energized during normal operation and can contribute to the transmission or distribution of electrical energy, but is not a neutral conductor. A neutral conductor is a conductor that is electrically connected to the neutral point and is capable of contributing to the distribution of electrical energy.In the European standard IEC 62196, the contacts referred to here as AC charging contacts are designated L1, L2, and L3 (live conductors) and N (neutral conductor), while the DC charging contacts are designated DC+ and DC-. This understanding is not contradicted by the fact that the European standard IEC 62196 also recognizes an operating mode in which DC charging occurs via contacts L1, L2, L3, and N. Preferably, the connections leading out of the housing are also contacted with the control unit, so that the temperature measurable at the DC charging contacts during AC charging can be referenced as the ambient temperature. This ambient temperature can be used as the minimum temperature for testing the functionality of the temperature sensors connected in series. Finally, the invention also relates to a method for operating a system consisting of a charging connector for electric and hybrid vehicles and a control unit, wherein the charging connector has AC charging contacts and temperature sensors, wherein each AC charging contact is assigned a temperature sensor for measuring the temperature of the respective AC contact, and the temperature sensors are connected in series, comprising the following method steps: S1) Detecting whether a charging process is currently taking place, S2) Measuring a temperature of the AC charging contacts when it has been detected that a charging process is currently taking place, S2a) Detecting whether AC charging is currently taking place, S2b) Measuring a temperature corresponding to the ambient temperature at the DC charging contacts when it has been detected that AC charging is taking place.S2c) Calculating the absolute temperature rise of the temperature at the AC charging contacts with the ambient temperature, S3a) Controlling the charging current depending on the absolute temperature of the AC charging contacts and S3) Determining the functionality of the temperature sensors. It is essential that the functionality of the temperature sensors can only be determined during a charging process. Preferably, the functionality test is performed continuously throughout the entire charging process. By referencing the ambient temperature, it is possible to measure an absolute temperature increase of the sensors, so that the charging current can be throttled when approaching an absolute maximum temperature. The invention is described in more detail below with reference to the drawings and preferred embodiments. In the drawings, Fig. 1 shows a charging connector in a perspective view according to a preferred embodiment of the invention, Fig. 2 shows a charging connector corresponding to the charging connector from Fig. 1 in a perspective view, Fig. 3 schematically shows a charging connector according to a preferred embodiment of the invention with a control unit, Fig. 4 schematically shows a circuit diagram according to a preferred embodiment of the invention, and Fig. 5 shows a flowchart for a method according to a preferred embodiment of the invention. Figure 1 shows a perspective view of a charging connector 1 according to a preferred embodiment of the invention. The charging connector 1 has a housing 7 and charging contacts arranged in the housing 7. These are, on the one hand, AC charging contacts 2 for AC charging and, on the other hand, DC charging contacts 9 for DC charging. The charging connector 1 shown in Figure 1 is a charging plug for installation in the body of an electric or hybrid vehicle. The charging connector 1 can be coupled to a corresponding charging connector 13, which is shown in Fig. 2. This is a charging coupler that can be attached to a charging cable and plugged into the charging connector. The charging coupler shown here is for AC charging and therefore has corresponding AC charging contacts 17, a protective contact 15, and communication contacts 16. Both the charging connector and the coupler shown here conform to the European standard IEC 62196 in terms of their mating interface. Figure 3 shows the charging plug 1 according to a preferred embodiment of the invention. Crucially, each of the AC charging contacts 2 in Figure 3 is provided with a linear temperature sensor 3. These linear temperature sensors 3 are arranged directly on the respective thermal contact elements 5 in the thermal connection areas 4. The thermal contact elements 5 are semicircular and have a radius corresponding to that of the AC charging contacts 2. This enables a particularly advantageous thermal connection between the AC charging contacts 2 and the thermal contact elements 5. Heat transfer by convection is reduced compared to the more advantageous heat transfer by conduction. The linear temperature sensors 3 arranged directly on the thermal contact elements 5 are connected in series. Figure 4 shows a circuit diagram according to a preferred embodiment of the invention. A first linear temperature sensor 3 is galvanically connected to the zero potential and to a second linear temperature sensor 3. The zero potential corresponds to a first terminal 6. Furthermore, the zero potential is galvanically connected to a first CAN bus terminal (controller area network bus) of a PESD2CAN (electrostatic discharge protection device). The first linear temperature sensor 3 is galvanically connected to the second linear temperature sensor 3 and to the terminal of the PESD2CAN located opposite the two CAN bus terminals. The second linear temperature sensor 3 is galvanically connected to the second CAN bus terminal of the PESD2CAN, the first CAN bus terminal of another PESD2CAN, and a third linear temperature sensor 3.The third linear temperature sensor is galvanically connected to the first linear temperature sensor 3 and to the terminal of the further PESD2CAN located opposite the two CAN bus terminals. The first linear temperature sensor 3 is galvanically connected to the second CAN bus terminal of the further PESD2CAN and to the second terminal 6, which carries the measurement signal. Figures 3 and 4 show that linear temperature sensors 3 connected in series can quickly register temperature changes at each AC charging contact 2. Furthermore, the series connection requires only two terminals 6, which extend from the housing 7 of the charging connector 1. The circuit diagram shown in Figure 4 is implemented on a printed circuit board 8 shown in Figure 3 within the housing 7. The terminals 6 extending from the housing 7 are galvanically connected to a control unit 10. Similarly, the DC charging contacts 9, equipped with linear temperature sensors 12, are also connected to the control unit 10 via terminals 14 extending from the housing 7. The linear temperature sensors 12 are connected to the DC charging contacts 9 by means of thermal contact areas 11. During an AC charging process, the DC charging contacts 9 initially typically have a temperature corresponding to the ambient temperature, which can then be used as a reference temperature by the control unit 10. Taking this reference temperature into account, the control unit 10 can determine the absolute temperature of the AC charging contacts 2. Since the four linear temperature sensors 3 are connected in series to the AC charging contacts 2, the resistance linearly correlated with temperature will be the sum of all the resistances of the four linear temperature sensors 3. Therefore, taking the reference temperature into account, the control unit 10 can define a minimum temperature and a maximum temperature specified by the standard. Simultaneously, the control unit 10 continuously measures an average temperature, allowing, for example, the identification of steep temperature increases or rapid temperature drops using gradient monitoring. This enables not only general temperature monitoring but also functional testing of both the temperature sensors and the charging electronics. Furthermore, the control unit 10 is designed to control the charging current based on the temperature. As soon as the control unit 10 measures a temperature approaching the maximum permissible temperature, which is determined by the sum of the maximum permissible temperature change and the ambient temperature, the charging current can be reduced.Throttled charging current results in a slower temperature rise at the AC charging contacts 2, which extends the charging process and achieves a higher state of charge for the battery. This is also illustrated in Fig. 5, which shows a flowchart for a method according to a preferred embodiment of the invention. In a first step S1, it is detected whether a charging process is currently taking place. Then, in step S2, if it has been detected that a charging process is taking place, the temperature at the AC charging contacts 2 is measured. Simultaneously, in step S2a, it is detected whether the charging process is an AC charging process. Then, in step S2b, if it has been detected that AC charging is taking place, a temperature corresponding to the ambient temperature is measured at the DC charging contacts 9. In step S2c, an absolute temperature rise at the AC charging contacts 2 is calculated based on the ambient temperature. Steps S2a to S2c take place simultaneously with step S2, the continuous measurement of a temperature.In the final steps S3 and S3a, both the functionality of the temperature sensors is checked and the temperature-dependent control of the charging current is carried out. Reference symbol list 1 Charging connector 2 AC charging contact 3 Linear temperature sensor 4 Thermal connection area 5 Thermal contact elements 6 Connection 7 Housing 8 Circuit board 9 DC charging contact 10 Control unit 11 Thermal connection area 12 Linear temperature sensor 13 Corresponding charging connector 14 Connections 15 Protective contact 16 Communication contact 17 Corresponding AC charging contact 18 PESD2CAN

Claims

System comprising a charging connector (1) for electric and hybrid vehicles and a control unit (10), wherein the charging connector (1) is provided with a housing (7) and AC charging contacts (2), DC charging contacts (9) and temperature sensors (3) arranged in the housing (7), wherein at least one temperature sensor (12) provided with a thermal connection area (11) for measuring the temperature of the DC charging contacts (9) is arranged on the DC charging contacts (9) and the terminals (15) of the temperature sensor (12) are brought out of the housing (7), wherein a temperature sensor (3) provided with a thermal connection area (4) for measuring the temperature of the respective AC charging contact (2) is arranged on each AC charging contact (2), the temperature sensors (3) are connected in series, and the two terminals (6) of the series connection are brought out of the housing (7).The terminals (6) leading out of the housing (7) are connected to the control unit (10) for receiving the signal from the temperature sensors (3) connected in series, and the control unit (10) is configured to determine the functionality of the temperature sensors (3) connected in series and to control the charging current as a function of the temperature measured by the temperature sensors (3), whereby the charging process is not interrupted when a limit temperature is reached, but rather the charging current is throttled as the limit temperature is approached, so that the charging process does not have to be interrupted, but continues continuously. System according to claim 1, wherein the control unit (10) is further configured to determine the functionality of the temperature sensors (3) connected in series by means of gradient monitoring. System according to one of claims 1 or 2, wherein the control unit (10) is configured to monitor the functionality of charging electronics used for the charging process. System according to one of claims 1 to 3, wherein the terminals (15) leading out of the housing (7) are contacted with the control unit (10) so that the temperature measurable at the DC charging contacts (9) can be referenced as ambient temperature during AC charging. System according to one of the preceding claims, wherein the temperature sensors (3) are linear temperature sensors. System according to one of the preceding claims, wherein the linear temperature sensors (3) are PTC elements. System according to one of the preceding claims, wherein the temperature sensors (3) and the two terminals (6) of the series circuit are arranged on a printed circuit board (8). System according to one of the preceding claims, wherein the thermal connection areas (4) are provided with thermal contact elements (5) with which a respective charging contact (2) can be thermally contacted. System according to claim 8, wherein the thermal contact elements (5) are not galvanically conductive. Use of a system according to any of the preceding claims on the body of an electric or hybrid vehicle. Method for operating a system comprising a charging connector (1) for electric and hybrid vehicles and a control unit (10), wherein the charging connector (1) has AC charging contacts (2) and temperature sensors (3), wherein each AC charging contact is assigned a temperature sensor (3) for measuring the temperature of the respective AC contact, and the temperature sensors (3) are connected in series, comprising the following method steps: S1) Detect whether a charging process is currently taking place, S2) Measure a temperature of the AC charging contacts (2) when it has been detected that a charging process is currently taking place, S2a) Detect whether AC charging is currently taking place, S2b) Measure a temperature corresponding to the ambient temperature at the DC charging contacts (9) when it has been detected that AC charging is taking place.S2c) Calculate the absolute temperature rise at the AC charging contacts (2) with the ambient temperature and S3) Determine the functionality of the temperature sensors (3).

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