Thermal detection and control of a wall plug

Abstract

Charging system (10) comprising a vehicle charging system (16), a vehicle wiring harness (50) and a plug assembly (22) operable for connecting the vehicle wiring harness (50) to a wall socket (20) used to supply power to the vehicle charging system (16), the plug assembly (22) comprising: a live contact (30) configured to allow current to flow from the wall socket (20) to the vehicle charging system (16); a neutral contact (32) configured to allow current to flow back from the vehicle charging system (16) to the wall socket (20); an earth contact configured to allow the vehicle charging system (16) to be connected to earth;and a temperature sensor that is operable to detect a temperature at the wall socket, wherein the vehicle charging system (16) is operable to control current flow through the live connector (30) as a function of temperature, wherein the current flow is controlled according to a scheme in which an amount of current flow is reduced proportionally to an increase in temperature, wherein a rate at which the amount of current flow is reduced is proportional to a rate at which the temperature increases, so that the amount of current flow is reduced more rapidly when the temperature increases more rapidly.;

Description

Cross-Reference to Related ApplicationsThis application claims priority to U.S. Provisional Application No. 61 / 445,714, entitled "Thermal Wall Plug Sensing and Control" (Thermal Sensing and Control of a Wall Plug), filed February 23, 2011, the disclosure of which is incorporated herein by reference in its entirety.Technical FieldThe present invention relates to thermal sensing of a wall plug and implementing a control strategy based on a temperature sensed or measured at a thermal connection with the wall plug for implementing control of a charging system used to enable plug charging of a vehicle via a wall power supply outlet or other vehicle connection.BackgroundWith the advent of electric and hybrid plug-in electric vehicles, there has been a need to build charging systems for charging vehicle systems that are used to enable electric drive-related operations, such as, but not limited to, batteries and capacitors. The charging system may be located wholly or partially within the vehicle and may be operable to enable charging operations with energy provided via a wall outlet or other interface leading to a household / power supply power network or other type of energy source. The charging system may include a plug assembly or other interface to establish an electrical connection with the wall outlet. US 2009 / 0 195 237 A1 discloses circuits for detecting aged electrical connector circuits and for avoiding potentially hazardous conditions resulting therefrom. In this case, a temperature of the circuits is detected when power is transmitted and the power transmission is interrupted when a temperature range is exceeded. DE 10 2009 034 886 A1 discloses a system consisting of a charging cable and an electric vehicle connected thereto and / or a charging station connected thereto. The charging cable has a charging cable plug which has a housing with electrical contacts designed for connection to a charging station or a vehicle. Based on a detected temperature, a coding element is influenced which indicates a maximum current intensity which can be transmitted by the charging cable. DE 10 2009 002 429 A1 discloses a system for detecting when a plug of a cable of a charging system for a hybrid / electric vehicle reaches a predefined temperature in order to interrupt the current flow through the cable at this time. US 2002 / 0 081 486 A1 discloses an electrical connector which is intended for charging batteries of electrical vehicles. It is intended to allow temperature detection. When the maximum operating temperature of the connector is exceeded, a charging system is to reduce or interrupt the charging current.SummaryA non-limiting aspect of the present invention contemplates sensing temperature at a connection between a wall outlet and a charging system. The sensed temperature may be used to enable control of charging system operations, monitoring wall socket performance or operating capabilities, and for any number of other reasons.The present invention contemplates a plug assembly operable to connect a vehicle wiring harness to a wall outlet used to enable powering a vehicle charging system. The plug assembly includes: a live plug contact configured to allow conduction of current from the wall socket to the vehicle charging system; a neutral plug contact configured to allow return of current from the vehicle charging system to the wall socket; a ground plug contact configured to allow connection of the vehicle charging system to ground; and a temperature sensor operable to sense a temperature at the wall socket.A non-limiting aspect of the present invention contemplates that a resistance of the temperature sensor is approximately equal to the temperature at the wall outlet.A non-limiting aspect of the present invention contemplates that the temperature sensor is one of a negative temperature coefficient (NTC) component, a positive temperature coefficient (PTC) component, and a thermistor.One non-limiting aspect of the present invention contemplates a housing shaped to enclose the temperature sensor and support the live, neutral and ground contacts such that at least a portion of each of the live, neutral and ground contacts extends outwardly of the housing for mating with corresponding receptacles of the wall outlet.A non-limiting aspect of the present invention contemplates that the housing is injection molded around the temperature sensor, the live plug, the neutral plug and the ground plug and is made of non-conductive, at least semi-rigid material.One non-limiting aspect of the present invention contemplates a live wire, a neutral wire, a ground wire, and a temperature wire connected to the live plug, the neutral plug, the ground plug, and the temperature sensor, respectively, each wire extending separately to the exterior of the housing within an insulated enclosure for receipt within a receptacle of the vehicle charging system.A non-limiting aspect of the present invention contemplates that a voltage of the temperature wire is measured by the vehicle charging system to determine the temperature.The vehicle charging system is operable to control current flow through the live connector as a function of temperature.The current flow is controlled according to a scheme in which an amount of current flow is decreased in proportion to an increase in temperature.One non-limiting aspect of the present invention contemplates that the amount of current flow through the vehicle charging system is set to a first level and defines the scheme of: decreasing the current flow from the first level to a second level if the increase in temperature is greater than a first amount and less than a second amount; and decreasing the current flow from the first level to a third level if the increase in temperature is greater than the second amount, wherein the third level is less than the second level.A non-limiting aspect of the present invention contemplates that the scheme determines that the flow of current is interrupted if the increase in temperature is greater than a third amount.A speed at which the amount of current flow is decreased is proportional to a speed at which the temperature increases, so that the amount of current flow is decreased more quickly as the temperature increases more quickly.One non-limiting aspect of the present invention contemplates a method of enabling control of a vehicle charging system based on a temperature at a connection external to the vehicle that is used to provide power to the vehicle charging system. The method may include: determining a first temperature at the connection prior to providing power to the vehicle charging system; determining a first amount of power required by the vehicle charging system to assist a charging operation; determining a second temperature at the connection while the first amount of power is provided to the vehicle charging system via the connection; and determining whether to enable continuous supply of power to the vehicle charging system at the first amount if a temperature delta between the first and second temperatures is less than a predetermined value.A non-limiting aspect of the present invention contemplates a control device of the vehicle charging system that determines whether to enable continuous delivery of power over the connection to the vehicle charging system at the first amount, wherein the control device reduces power delivered over the connection from the first amount to at least a second amount if the temperature delta exceeds the predetermined value.A non-limiting aspect of the present invention contemplates determining the temperature delta to be equal to the second temperature minus the first temperature.A non-limiting aspect of the present invention contemplates determining the temperature delta to be equal to a rate change from the first temperature to the second temperature.A non-limiting aspect of the present invention contemplates determining the predetermined value as a first value based on one of the following conditions: the first temperature is less than a first threshold, a current geographic region, and a time of day, and a second value based on one of the following conditions: the first temperature exceeds the first threshold, the current geographic region, and the time of day, the second value being less than the first value.A non-limiting aspect of the present invention contemplates a charging system including: a controller operable to control a charging system used to electrically charge a storage element; a temperature sensor operable to determine a temperature proximate an interface between the charging system and a power source, the charging system utilizing energy originating from the power source to charge the storage element; and wherein the controller adjusts current drawn by the charging system via the interface based on the temperature.One non-limiting aspect of the present invention contemplates that the controller reduces current drawn by the charging system if a temperature delta of the temperature measured over time is greater than a predetermined value.One non-limiting aspect of the present invention contemplates that the temperature sensor is one of a negative temperature coefficient (NTC) component, a positive temperature coefficient (PTC) component, and a thermistor, and is included in a connector assembly of the charging system.BRIEF DESCRIPTION OF THE DRAWINGThe present invention is set forth with particularity in the appended claims. However, other features of the present invention will become more apparent and the present invention will be best understood by reference to the following detailed description when taken in conjunction with the accompanying drawings, in which: FIG. 1 illustrates a charging system according to a non-limiting aspect of the present invention, FIG. 2 illustrates a multipolar plug assembly with a temperature sensor according to a non-limiting aspect of the present invention, FIG. 3 illustrates a cable set and a plug assembly housing according to a non-limiting aspect of the present invention; and FIG. 4 illustrates a flow diagram of a method for controlling a charging system according to a non-limiting aspect of the present invention.Detailed DescriptionAs required, specific embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, particular structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.FIG. 1 illustrates a charging system 10 viewed through a non-limiting aspect of the present invention in which a vehicle 12 is connected to a power source 14 to enable operation of a charging system 16 with power provided from the power source 14 via a wall outlet 20 and a plug assembly 22. The present invention is intended primarily for exemplary and non-limiting purposes with respect to enabling the supply of AC power to the charging system 16 for use in DC and / or AC charging / powering a vehicle subsystem (not shown), such as a battery, capacitor, etc. However, the present invention contemplates its use and application in any number of vehicle and non-vehicle environments in which it may be desirable to monitor conditions of connection between the wall socket 20 and the plug assembly 22 or a corresponding connection point of such another application.The wall socket 20 is shown as a two pole type having live and neutral sockets 26, 28 formed by opposing resilient members biased inwardly to press against corresponding live and neutral plug contacts 30, 32 of the plug assembly 22. This type of connection to resilient elements is based on a normal force of the resilient elements when carrying the current flow. The amount of current flow that can be carried therethrough is proportional to the normal force, causing the joint region to generate more heat at the same amount of current flow if the normal force between the connectors is decreased. The resilient members 26, 28, or other member of a deformable or fatiable material, may thus lose some of its current carrying capability due to failure of the material and / or inability to maintain an optimum level of normal force at the connection to the plug contacts 30, 32. Even in the absence of such a failure, performance may be degraded if the plugs and / or jacks 30, 32 are improperly designed for the desired paired system.The wall outlet 20 may be connected to a power supply network or other power source; for example, if the wall outlet 20 is part of a charging station, the wall outlet 20 may be used to enable transfer of power from the charging station to the vehicle charging system 16. The plug assembly 22 further includes a temperature sensor 36 operable to assess a temperature near a connection between the plugs and jacks 30, 32. The temperature sensor 36 may be a thermistor, a positive temperature coefficient (PTC) component, a negative temperature coefficient (NTC) component, or other element suitable for measuring temperature, such as, but not limited to, an infrared sensor of the type disclosed in U.S. Provisional Patent Application No. 61 / 441,404, EV Cordset Temperature Measurement (Electric Vehicle Harness Temperature Measurement), the disclosure of which is incorporated herein by reference in its entirety.A live wire 40 and a neutral wire 42 may be connected to the live and neutral plug contacts 30, 32, respectively, to establish current flow with the vehicle charging system 16. For example, the live connection 30 may be used to route current to the charging system 16, and the neutral connection 32 may be used to route current back to the power source 14. The sensor wires 44, 46 may extend from the temperature sensor 36 to the charging system 16 to enable reporting of sensed temperature values, such as by creating a circuit loop. If the temperature sensor 36 is a resistive element having a resistance that varies with temperature, the sensor wires 44, 46 may be used to allow a voltage drop across the temperature sensor 36 to be measured. The charging system 16 may include a processor or other logically operating element to determine a temperature value based on the corresponding voltage measurement.The wires 40, 42, 44, 46 may be enclosed within an insulated material 48 of a cable set 50, such as the cable set shown in FIG. 3. The temperature sensor 36 and the portion of the live and neutral plug contact that does not extend outward may be injection molded into a housing 52. The system 10 has been described with respect to an exemplary arrangement in which the wall outlet 20 includes only live and neutral sockets 26, 28. However, the present invention is not intended to be so limited and contemplates its use with other wall receptacles 20 having more or fewer receptacles, including three-pole receptacles having a ground receptacle, five-pole receptacles corresponding to European three-phase operation, etc. The plug assembly 22 is then adapted for use with these other arrangements, such as by including a ground plug and ground wire in a similar arrangement to the live and neutral plug contacts 30, 32 and the wires 40, 42 described above.FIG. 2 illustrates an exemplary multipolar plug assembly 60 having a temperature sensor 62 according to a non-limiting aspect of the present invention. The plug assembly 60 includes seven terminals including a "plug present" terminal 64, a signal terminal 66, and five terminals for supporting European alternating current (e.g., three three three AC live conductors 68, 70, 72, a neutral conductor 74, and a ground conductor 76). The terminals 64, 66, 68, 70, 72, 74, 76 may operate in accordance with SAE specification J1772. U.S. Pat. No. 7,878,866, entitled "Connector Assembly for Vehicle Charging" (connector assembly for vehicle charging), the disclosure of which is incorporated herein by reference in its entirety, discloses a similar five terminal multipolar arrangement that can be modified in accordance with the present invention to include the thermistor. The temperature sensor 62 shown in FIG. 2 may be arranged similar to the temperature sensor 36 described above and injection molded into a housing or otherwise positioned proximate a connection region between the plug assembly 22 and the wall outlet 20.FIG. 4 illustrates a flow diagram 80 of a method for controlling the charging system 16 according to a non-limiting aspect of the present invention. The method may be embodied in a computer readable medium or other source embodied with a processor, controller, or other logically executing unit having capabilities to issue instructions or otherwise enable the operations and other functions required to control the charging system 16, as contemplated by the present invention.Block 82 relates to determining a temperature during or prior to insertion of the plug assembly into the wall socket. The temperature may be a temperature sensed with the temperature sensor 36 or another sensor, such as a vehicle ambient air temperature sensor. One goal of this pre-charge temperature measurement is to determine an initial set of operating conditions of the charging system, wall socket, charging station, etc., which can then be used to manage the operation of the charging system. This initial measurement is described as occurring before the charging system 16 receives a sufficient amount of current to perform a charging operation. However, this is done without intending to limit the scope and intent of the present invention since a similar reference value or reference point may be detected during a normal charging operation.Block 84 relates to determining a desired amount of current to be drawn across the connection to enable charging of the charging system 16. The charging system 16 may be operable to support any number of charging operations with any number of power consumption requests. To assist in description, and without intending to unduly limit the scope and intent of the present invention, the present invention is primarily described in that the charging system attempts to perform a charging operation in a shortest possible time, such as by receiving as much current as possible.The desired current draw may correspond to a maximum operating capability of the wall outlet 22, the cable set 50, and / or the charging system 16. Data may be provided or otherwise determined via the wall outlet 20 to identify the maximum or desired amount of current. The temperature sensed at block 82 may also optionally be used in addition to the other specified parameters to determine the desired amount of current draw. For example, the maximum current draw capabilities of the system 10 may be equal to a first value according to the particular arrangement of the system 10 when operating under normal or ideal operating conditions. The desired amount of current determined in block 84 may be decreased from the first value in proportion to the temperature measured in block 82, which deviates from the normal or ideal operating value or range used to set the maximum current draw. Of course, other constraints detected for the wall outlet 20 or the charging system 16, such as those determined based on the data transfer, may be used to determine the desired current draw.Block 86 relates to driving the charging system to begin current draw at the desired level of current draw determined in block 84. The temperature measurement of block 82 may take place before starting to draw current at the desired level in block 86. The desired current draw may be adjusted to correspond to operating changes in block 86, for example, by increasing the desired current draw if the charging system desires more current, such as to assist additional charging operations.Block 88 relates to determining a temperature delta based on a temperature measured with the temperature sensor 36. This second temperature measurement is made after the first temperature measurement of block 82. The temperature delta may be equal to a difference between the first and second temperature measurements, a temperature rate of change between the first and second temperature measurements, a combination thereof, and the like. One of the goals of determining the temperature delta is to evaluate how quickly or seriously the temperature of the wall socket 20 changes due to the charging process, i.e. due to the current flow through the connection area. This may be helpful in adjusting the current drawn by the charging system 16, as described in more detail below, to ensure that the wall socket 20 is operated within a desired temperature range.Block 90 relates to determining whether the temperature delta exceeds a threshold. The threshold generally corresponds to a desired temperature operating range of the wall outlet 20, which may vary depending on the type of wall outlet 20, operating conditions / requirements, and a need to use the wall outlet 20. (For example, in an emergency, it may be acceptable to overload the socket 20.) As such, the threshold may be varied depending on any number of considerations. One non-limiting aspect of the present invention contemplates setting the threshold to a value corresponding to an undesired increase in temperature or an undesired rate of change in temperature, which rather reflects a need to reduce the current drawn and / or indicate a need to interrupt current draw.Block 92 relates to decreasing the current drawn if the temperature delta is exceeded. Current draw may be reduced in proportion to an amount by which the temperature delta exceeded the threshold, according to a step technique in which incremental changes are made until the desired temperature range is reached, and other methodologies. The temperature delta after reducing the current draw is again checked in block 90 to determine if further reductions are needed to ensure operation within a desired temperature range. Optionally, the need to increase current draw may also be determined, such as when current draw has been reduced too much or unnecessarily reduced in view of a transient event, so that current may be increased to maintain maximum current draw for the desired operating temperature. The threshold used in each subsequent temperature delta analysis may be varied depending on the current operating conditions, the previous temperature measurement, etc.

Claims

A charging system (10) comprising a vehicle charging system (16), a vehicle harness (50), and a plug assembly (22) operable to connect the vehicle harness (50) to a wall socket (20) used to enable powering the vehicle charging system (16), the plug assembly (22) comprising: a live plug contact (30) configured to enable routing power from the wall socket (20) to the vehicle charging system (16); a neutral plug contact (32) configured to enable returning power from the vehicle charging system (16) to the wall socket (20); a ground plug contact configured to enable connecting the vehicle charging system (16) to ground; A temperature sensor operable to sense a temperature at the wall outlet, wherein the vehicle charging system (16) is operable to control current flow through the live connector (30) as a function of temperature, wherein the current flow is controlled according to a scheme in which an amount of current flow is decreased in proportion to an increase in temperature, wherein a rate at which the amount of current flow is decreased is proportional to a rate at which the temperature increases such that the amount of current flow is decreased more rapidly as the temperature increases.The charging system of claim 1, wherein the amount of current flow through the vehicle charging system (16) is set to a first level and the scheme defines: decreasing the current flow from the first level to a second level if the increase in temperature is greater than a first amount and less than a second amount; and decreasing the current flow from the first level to a third level if the increase in temperature is greater than the second amount, wherein the third level is less than the second level.The charging system of claim 2, wherein the scheme determines that the current flow is interrupted if the increase in temperature is greater than a third amount.The charging system according to any one of the preceding claims, wherein a resistance of the temperature sensor approximately corresponds to the temperature at the wall socket (20).The charging system according to any preceding claim, wherein the temperature sensor (36) is one of a negative temperature coefficient (NTC) component, a positive temperature coefficient (PTC) component, and a thermistor.The charging system of any preceding claim, further comprising a housing (52) shaped to enclose the temperature sensor (36) and support the live plug (36), the neutral plug (32), and the ground plug such that at least a portion of each of the live, neutral, and ground plugs (30, 32) extends outwardly of the housing (52) for insertion into corresponding receptacles (26, 28) of the wall socket (20).Charging system according to Claim 6, wherein the housing (52) is injection-moulded around the temperature sensor (36), the live plug contact (30), the neutral plug contact (32) and the earth plug contact and is made of non-conductive, at least semi-rigid material.The charging system of claim 7, further comprising a live wire (40), a neutral wire (42), a ground wire and a temperature wire (44, 46) connected to the live plug contact (30), the neutral plug contact (32), the ground plug contact and the temperature sensor (36), respectively, each wire separately extending outside the housing (52) within an insulated enclosure for receipt within a receptacle of the vehicle charging system (16).The charging system of claim 8, wherein a voltage of the temperature wire (44, 46) is measured by the vehicle charging system (16) to determine the temperature.

Images