Description:FIELD OF THE INVENTION

[1] The present disclosure generally relates to a power cable assembly. More particularly, the present disclosure relates to a power cable assembly in an electric vehicle charging station.

BACKGROUND

[2] Electric vehicle charging stations are stations for charging batteries of electric vehicles, for example, electric cars, electric scooters, and electric bikes. These stations come in various levels, for example, a level 1 charging station is for standard residential outlets, a level 2 charging station is for public places, and level 3 charging station is for fast charging or direct current (DC) fast charging stations.

[3] A charging station includes mainly a power supply unit, an electronic control unit, and an electric charging unit. The charging station draws power from a grid and the current is transmitted using a high power rating cable. The current that flows from the grid to the charging station is AC current which is typically converted to DC current for vehicle battery charging. If the vehicle comprises an onboard charger, then AC charging is feasible without the requirement of converting the AC current to DC current.

[4] Often, when power is transmitted through the power cable, the cable develop hot spots at certain regions, typically in regions close to the vehicle connector. These hot spots are developed due to the constant transmission of high current. Hot spots are excessive heat generated in specific regions. If the heat is not dissipated or removed efficiently, the hot spot can lead to melting of the insulator covering the power cable and/or the connector.

[5] Conventional methods to solve the hot spot issue include increasing wire cross section or using liquid to cool the conductor in the power cable. Increasing the cross section of wire or using liquid cooling increases the cost and makes the whole power cable assembly bulky.

[6] For instance, one such prior art relates to a large-current cable, a charging cable assembly and an electric automobile charging system are disclosed, the charging cable assembly is used for rapid charging of an electric automobile, the large-current cable comprises at least two wire cores, each wire core comprises a conductor, the conductor is formed by combining a plurality of capillary heat pipes, the capillary heat pipes are tubular, and two ends of each capillary heat pipe are sealed to form a cavity in the capillary heat pipe. A liquid working medium is arranged in the cavity, the capillary heat pipe comprises an integral heating section and a condensation section, the integral heating section is used for absorbing heat to convert the liquid working medium into a gaseous working medium, the condensation section is used for dissipating heat to convert the gaseous working medium into the liquid working medium, and the condensation section is communicated with the integral heating section and located at one end of the integral heating section. The large-current cable can improve the current-carrying capability, the heat dissipation capability, and the portability of a charging cable, and compared with a liquid cooling charging cable, the complexity and the cost of a system are greatly reduced. However, the arrangement disclosed in the prior art is bulky and complex.

[7] Therefore, there is a need to efficiently remove hot spot build up in power cable of charging stations.

SUMMARY

[8] This summary is provided to introduce a selection of concepts, in a simplified format, that is further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.

[9] The main objective of the present disclosure is to provide a mechanism to remove heat generated due to hot spots in power cables of electric vehicle charging stations. Accordingly, a power cable assembly to remove heat generated due to hot spots is disclosed.

[10] In an embodiment of the present disclosure, a power cable assembly is disclosed. The power cable assembly includes a power cable. The power cable includes a plurality of wires enclosed by an insulator. The power cable is configured to be filled by a phase changing liquid between the insulator and the plurality of wires. The power cable includes a first terminal and a second terminal connected respectively to a first end and a second end of the plurality of wires. The second terminal is configured to be coupled to a vehicle connector. The power cable includes a temperature sensor coupled to a region of the insulator. The temperature sensor is configured to sense the temperature of a pre-defined region of the power cable.

[11] To further clarify the advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[12] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[13] Figure 1 illustrates a perspective side view of a two-wheeler vehicle having a power cable assembly, according to an embodiment of the present disclosure;

[14] Figure 2 illustrates a schematic representation of the power cable assembly, according to an embodiment of the present disclosure; and

[15] Figure 3 illustrates change in phase of a phase changing liquid in a power cable, according to an embodiment of the present disclosure.

[16] Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present invention. Furthermore, in terms of the construction of power cable assembly, one or more components of the power cable assembly may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

DETAILED DESCRIPTION OF FIGURES

[17] For the purpose of promoting an understanding of the principles of the present disclosure, reference will now be made to the various embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present disclosure is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the present disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the present disclosure relates.

[18] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the present disclosure and are not intended to be restrictive thereof.

[19] Whether or not a certain feature or element was limited to being used only once, it may still be referred to as “one or more features” or “one or more elements” or “at least one feature” or “at least one element.” Furthermore, the use of the terms “one or more” or “at least one” feature or element do not preclude there being none of that feature or element, unless otherwise specified by limiting language including, but not limited to, “there needs to be one or more…” or “one or more elements is required.”

[20] Reference is made herein to some “embodiments.” It should be understood that an embodiment is an example of a possible implementation of any features and/or elements of the present disclosure. Some embodiments have been described for the purpose of explaining one or more of the potential ways in which the specific features and/or elements of the proposed disclosure fulfil the requirements of uniqueness, utility, and non-obviousness.

[21] Use of the phrases and/or terms including, but not limited to, “a first embodiment,” “a further embodiment,” “an alternate embodiment,” “one embodiment,” “an embodiment,” “multiple embodiments,” “some embodiments,” “other embodiments,” “further embodiment”, “furthermore embodiment”, “additional embodiment” or other variants thereof do not necessarily refer to the same embodiments. Unless otherwise specified, one or more particular features and/or elements described in connection with one or more embodiments may be found in one embodiment, or may be found in more than one embodiment, or may be found in all embodiments, or may be found in no embodiments. Although one or more features and/or elements may be described herein in the context of only a single embodiment, or in the context of more than one embodiment, or in the context of all embodiments, the features and/or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and/or elements described in the context of separate embodiments may alternatively be realized as existing together in the context of a single embodiment.

[22] Any particular and all details set forth herein are used in the context of some embodiments and therefore should not necessarily be taken as limiting factors to the proposed disclosure.

[23] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by “comprises... a” does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

[24] Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.

[25] For the sake of clarity, the first digit of a reference numeral of each component of the present disclosure is indicative of the Figure number, in which the corresponding component is shown. For example, reference numerals starting with digit “1” are shown at least in Figure 1. Similarly, reference numerals starting with digit “2” are shown at least in Figure 2.

[26] An Electric Vehicle (EV) or a battery powered vehicle including, and not limited to two-wheelers such as scooters, mopeds, motorbikes/motorcycles; three-wheelers such as auto-rickshaws, four-wheelers such as cars and other Light Commercial Vehicles (LCVs) and Heavy Commercial Vehicles (HCVs) primarily work on the principle of driving an electric motor using the power from the batteries provided in the EV. Furthermore, the electric vehicle may have at least one wheel which is electrically powered to traverse such a vehicle. The term ‘wheel’ may be referred to any ground-engaging member which allows traversal of the electric vehicle over a path. The types of EVs include Battery Electric Vehicle (BEV), Hybrid Electric Vehicle (HEV) and Range Extended Electric Vehicle. However, the subsequent paragraphs pertain to the different elements of a Battery Electric Vehicle (BEV).

[27] In construction, as illustrated in Figure 1, an EV (10) typically comprises a battery or battery pack (12) enclosed within a battery casing and includes a Battery Management System (BMS), an on-board charger (14), a Motor Controller Unit (MCU), an electric motor (16) and an electric transmission system (18). The primary function of the above-mentioned elements is detailed in the subsequent paragraphs: The battery of an EV (10) (also known as Electric Vehicle Battery (EVB) or traction battery) is re-chargeable in nature and is the primary source of energy required for the operation of the EV, wherein the battery (12) is typically charged using the electric current taken from the grid through a charging infrastructure (20). The battery may be charged using Alternating Current (AC) or Direct Current (DC), wherein in case of AC input, the on-board charger (14) converts the AC to DC and charges the battery. However, in case of DC charging, the on-board charger (14) is bypassed, and the current is transmitted directly to the battery.

[28] The battery (12) is made up of a plurality of cells which are grouped into a plurality of modules in a manner in which the temperature difference between the cells does not exceed 5 degrees Celsius. The terms “battery”, “cell”, and “battery cell” may be used interchangeably and may refer to any of a variety of different rechargeable cell compositions and configurations including, but not limited to, lithium-ion (e.g., lithium iron phosphate, lithium cobalt oxide, other lithium metal oxides, etc.), lithium-ion polymer, nickel metal hydride, nickel cadmium, nickel hydrogen, nickel-zinc, silver zinc, or other battery type/configuration. The term “battery pack” as used herein may be referred to multiple individual batteries enclosed within a single structure or multi-piece structure. The individual batteries may be electrically interconnected to achieve a desired voltage and capacity for a desired application. The Battery Management System (BMS) is an electronic system whose primary function is to ensure that the battery (12) is operating safely and efficiently. The BMS continuously monitors different parameters of the battery such as temperature, voltage, current and so on, and communicates these parameters to the Electronic Control Unit (ECU) and the Motor Controller Unit (MCU) in the EV using a plurality of protocols including and not limited to Controller Area Network (CAN) bus protocol which facilitates the communication between the ECU/MCU and other peripheral elements of the EV (10) without the requirement of a host computer.

[29] The MCU primarily controls/regulates the operation of the electric motor based on the signal transmitted from the vehicle battery, wherein the primary functions of the MCU include starting of the electric motor (16), stopping the electric motor (16), controlling the speed of the electric motor (16), enabling the vehicle to move in the reverse direction and protect the electric motor (16) from premature wear and tear. The primary function of the electric motor (16) is to convert electrical energy into mechanical energy, wherein the converted mechanical energy is subsequently transferred to the transmission system of the EV to facilitate movement of the EV. Additionally, the electric motor (16) also acts as a generator during regenerative braking (i.e., kinetic energy generated during vehicle braking/deceleration is converted into potential energy and stored in the battery of the EV). The types of motors generally employed in EVs include, but are not limited to DC series motor, Brushless DC motor (also known as BLDC motors), Permanent Magnet Synchronous Motor (PMSM), Three Phase AC Induction Motors and Switched Reluctance Motors (SRM).

[30] The transmission system (18) of the EV (10) facilitates the transfer of the generated mechanical energy by the electric motor (16) to the wheels (22a,22b) of the EV. Generally, the transmission systems (18) used in EVs include single speed transmission system and multi-speed (i.e., two-speed) transmission system, wherein the single speed transmission system comprises a single gear pair whereby the EV is maintained at a constant speed. However, the multi-speed/two-speed transmission system comprises a compound planetary gear system with a double pinion planetary gear set and a single pinion planetary gear set thereby resulting in two different gear ratios which facilitates higher torque and vehicle speed.

[31] In one embodiment, all data pertaining to the EV (10) and/or charging infrastructure (20) are collected and processed using a remote server (known as cloud) (24), wherein the processed data is indicated to the rider/driver of the EV (10) through a display unit present in the dashboard (26) of the EV (10). In an embodiment, the display unit may be an interactive display unit. In another embodiment, the display unit may be a non-interactive display unit.

[32] Embodiments of the present disclosure provide a power cable inside the charging infrastructure (20). The charging infrastructure (20) is interchangeably referred to as charging station in the present disclosure.

[33] Figure 2 illustrates a power cable assembly (200) to efficiently remove heat generated due to hot spots. The power cable assembly (200) includes a power cable (205). The power cable (205) is within the charging infrastructure (20), wherein the power cable (205) includes a plurality of wires (210) enclosed by an insulator (215). In one embodiment, the power cable (205) is a 16 sq mm cable. It is to be noted that power cables having various dimensions can also be used in the power cable assembly (200), for example, a 10 sq mm power cable can also be used.

[34] The power cable (205) is configured to be filled with a phase changing liquid (220) between the insulator (215) and the plurality of wires (210). In one embodiment, the phase changing liquid (220) is an engineered liquid or working liquid having a boiling point around 65 deg C. Typically, the vehicle (10) has to work at a higher ambient temperature of 50 deg C. There needs to be a temperature difference between the ambient temperature and a vapor temperature for condensation. Hence the phase changing liquid (220) having boiling point at 65 deg C is chosen in the present disclosure. However, other liquids having boiling point above 50 deg C and less than 65 deg C may also be used inside the power cable (205).

[35] Referring to Figure 2, the power cable (205) includes a first terminal (225A) and a second terminal (225B) connected respectively to a first end (230A) and a second end (230B) of the plurality of wires (210). The second terminal (225B) is configured to be coupled to a vehicle connector (235). The power cable (205) is so placed that the contact, second terminal (225B) in the vehicle connector (235) is at a lower height than the rest of the power cable (205). In an embodiment, the power cable (205) is placed vertically with the vehicle connector (235) contact at the lowest height. This is because, when the phase changing liquid (220) gets heated up and becomes vaporized, it travels upwards in the tube and the vapor when condensed flows back due to gravity. In one embodiment, the power cable (205) and the vehicle connector (235) may be coplanar.

[36] The power cable (205) includes a temperature sensor (240) coupled to a region of the insulator (215) which is proximal to the second terminal (225B). Further, the temperature sensor (240) is configured to sense a temperature of a pre-defined region of the power cable (205). In one embodiment, the temperature sensor (240) is a thermistor. The thermistor can be a positive temperature coefficient thermistor or a negative temperature coefficient thermistor. The temperature sensor (240) may be affixed to the region of the insulator (215) proximal to the second terminal (225B) as illustrated in Figure 2.

[37] The power cable assembly (200) includes a first heat shrink tube (245A) and a second heat shrink tube (245B) coupled to the first end (230A) and the second end (230B) of the plurality of wires (210). The first heat shrink tube (245A) and the second heat shrink tube (245B) are coupled to the first terminal (225A) and the second terminal (225B) respectively. In one embodiment, the heat shrink tubes are glued to the plurality of wires (210) and seals the wires (210). Further, the plurality of wires (210) are crimped to the contacts of the vehicle connector (235).

[38] Referring to Figure 3, the phase changing liquid (220) is converted to vapor (V) due to heat (H) and flows upward towards the first terminal (225A). The phase changing liquid (220) undergoes a phase change to a vapor phase when the sensed temperature is greater than a hotspot threshold temperature. It is to be noted that the first terminal (225A) is a terminal with lower temperature. Further, the generated vapor (V) undergoes condensation to form the phase changing liquid (220) and flows towards the second terminal (225B). The phase change of the phase changing liquid (220) from a liquid phase to a vapor phase and again from the vapor phase to the liquid phase enables cooling of the power cable (205). The above mentioned cycles keeps repeating to ensure that the hot spot created near the vehicle connector (235) is neutralized.

[39] In one embodiment, the power cable assembly (200) includes a reservoir (250) arranged external to the power cable (205) and for storing the phase changing liquid (220). The power cable assembly (200) includes a pump (255) connected to the reservoir (250). Further, the power cable assembly (200) includes an Electronic Control Unit (ECU) (260) communicatively coupled to the temperature sensor (240) and the pump (255). The ECU (260) is configured to actuate the pump (255) to feed a predefined quantity of the phase changing liquid (220) from the reservoir (250) to in-between the insulator (215) and the plurality of wires (210). The pump (255) is actuated when the sensed temperature by the temperature sensor (240) is recurrently greater or equal to a hotspot threshold temperature for a predefined time interval. In one example, the hotspot threshold temperature is 65 deg C and the predefined time interval is 1 minute and sampled every 10 seconds.

[40] The predefined quantity of the phase changing liquid (220) can be any one of the following, i.e., it can be:
30% of V, for a power cable of length <1m;
40% of V, for a power cable of length >1m and <2m; and
60% to 70% of V, for a power cable of length >2m, wherein V is free volume in the power cable.

[41] Further, the free volume (V) in the power cable (205) can be calculated as below:
a. Measure or obtain the Internal diameter of the insulation (D)
b. Measure or obtain the cross sectional area of the copper strands (A)
c. From this calculate the annular gap and multiply by the length of the cable (L)
d. Volume (V) = (22xDxD/7-A)L.

[42] Referring to Figure 2, the ECU (260) is communicatively coupled to a power source (265) and the temperature sensor (240). The ECU (260) is configured to control flow of current from the power source (265) to the power cable (205) when the sensed temperature is greater or equal to the hotspot threshold temperature. The temperature of the wires (210) is continuously measured through the temperature sensor (240). The amount of current flowing through the connector contact is dynamically adjusted by a processing circuitry within the power source (265), such as the grid during vehicle charging, so that the temperature is not allowed to exceed a certain predetermined maximum value, i.e., the hot spot threshold temperature.

[43] The power cable (205) is configured for charging an electric vehicle (10). The power cable (205) with the phase changing liquid (220) has various advantages. It removes heat due to hot spot and protects the insulator (215) and the vehicle connector (235). Further, the power cable (205) with the phase changing liquid (220) allows faster charging thereby increasing the number of vehicles that can be charged for a given time duration as compared to existing charging stations.

[44] Furthermore, embodiments of the disclosed devices and systems may be readily implemented, fully or partially, in software using, for example, object or object-oriented software development environments that provide portable source code that can be used on a variety of computer platforms. Alternatively, embodiments of the disclosed methods, processes, modules, devices, systems, and computer program product can be implemented partially or fully in hardware using, for example, standard logic circuits or a very-large-scale integration (VLSI) design. Other hardware or software can be used to implement embodiments depending on the speed and/or efficiency requirements of the systems, the particular function, and/or particular software or hardware system, microprocessor, or microcomputer being utilized.

[45] In this application, unless specifically stated otherwise, the use of the singular includes the plural and the use of “or” means “and/or.” Furthermore, use of the terms “including” or “having” is not limiting. Any range described herein will be understood to include the endpoints and all values between the endpoints. Features of the disclosed embodiments may be combined, rearranged, omitted, etc., within the scope of the invention to produce additional embodiments. Furthermore, certain features may sometimes be used to advantage without a corresponding use of other features.

[46] List of reference numerals:
Components Reference numerals
Power cable assembly 200
Plurality of wires 210
Insulator 215
Phase changing liquid 220
First terminal 225A
Second terminal 225B
Vehicle connector 235
Temperature sensor 240
First heat shrink tube 245A
Second heat shrink tube 245B
Reservoir 250
Pump 255
Electronic control unit (ECU) 260
Power source 265
Electric vehicle 10
First end 230A
Second end 230B

, Claims:1. A power cable assembly (200) comprising:
a power cable (205) comprising:
a plurality of wires (210) enclosed by an insulator (215), wherein the power cable (205) is configured to be filled by a phase changing liquid (220) between the insulator (215) and the plurality of wires (210); and
a first terminal (225A) and a second terminal (225B) connected respectively to a first end (230A) and a second end (230B) of the plurality of wires (210), wherein the second terminal (225B) is configured to be coupled to a vehicle connector (235); and
a temperature sensor (240) coupled to a region of the insulator (215), wherein the temperature sensor (240) is configured to sense a temperature of a pre-defined region of the power cable (205).

2. The power cable assembly (200) as claimed in claim 1, comprising a first heat shrink tube (245A) and a second heat shrink tube (245B) coupled to the first end (230A) and the second end (230B) of the plurality of wires (210), wherein the first heat shrink tube (245A) and the second heat shrink tube (245B) are coupled to the first terminal (225A) and the second terminal (225B) respectively.

3. The power cable assembly (200) as claimed in claim 1, comprising:
a reservoir (250) arranged external to the power cable (205) and for storing the phase changing liquid (220);
a pump (255) connected to the reservoir (250); and
an electronic control unit (ECU) (260) communicatively coupled to the temperature sensor (240) and the pump (255), wherein the ECU (260) is configured to actuate the pump (255) to feed a predefined quantity of the phase changing liquid (220) from the reservoir (250) to in-between the insulator (215) and the plurality of wires (210), wherein the pump (255) is actuated when the sensed temperature is recurrently greater or equal to a hotspot threshold temperature for a predefined time interval.

4. The power cable assembly (200) as claimed in claim 3, wherein the ECU (260) is
a. communicatively coupled to a power source (265) and the temperature sensor (240); and
b. configured to control flow of current from the power source (265) to the power cable (205) when the sensed temperature is greater or equal to the hotspot threshold temperature.

5. The power cable assembly (200) as claimed in claim 3, wherein the predefined quantity of the phase changing liquid (220) is one of:
30% of V, for the power cable (205) of length <1m;
40% of V, for the power cable (205) of length >1m and <2m; and
60% to 70% of V, for the power cable (205) of length >2m, wherein V is free volume in the power cable (205).

6. The power cable assembly (200) as claimed in claim 1, wherein the power cable (205) is configured for charging an electric vehicle (10).

7. The power cable assembly (200) as claimed in claim 1, wherein the phase changing liquid (220) undergoes a phase change to a vapor phase when the sensed temperature is greater than a hotspot threshold temperature.

8. The power cable assembly (200) as claimed in claim 1, wherein generated vapor of the phase changing liquid (220) flows towards the first terminal (225A), wherein the first terminal (225A) is a terminal with lower temperature.

9. The power cable assembly (200) as claimed in claim 1, wherein the generated vapor undergoes condensation to form the phase changing liquid (220) and flows towards the second terminal (225B).

10. The power cable assembly (200) as claimed in claim 1, wherein a phase change of the phase changing liquid (220) from a liquid phase to a vapor phase and again from the vapor phase to the liquid phase enables cooling of the power cable (205).