Abstract:
A proximity detection circuit is operable to detect connection of a cordset to a vehicle charging system or connection of another device to some other electrical circuit where it may be desirable to facilitate detection while a controller or other current drawing source is inactive.

Description:
TECHNICAL FIELD 
     The present invention relates to proximity detection circuits of the type suitable for use with on-board vehicle chargers to detect connection to a cordset or other element used to facilitate vehicle charging. 
     BACKGROUND 
     An on-board vehicle charger may be used to charge a high voltage battery found in a hybrid electric or electric vehicle to provide energy to an electrically powered motor. In some cases, the charging may be facilitated with a cordset or other element having capabilities to facilitate current delivery to the on-board charger, such as from a wall charger or other type of charging station. The cordset may include an adaptor to facilitate attachment to an outlet or other receptacle associated with the on-board charger. The on-board charger may include electronics or other elements to control and manage current flow to the high voltage battery and other the related charging operations. 
     SUMMARY 
     One non-limiting aspect of the present invention contemplates a proximity detection circuit for use in awakening a microcontroller to detect connection of a charging cordset to a receptacle of a vehicle charging system where the cordset has a proximity pin that plugs into a terminal of the receptacle when the cordset is connected. The proximity detection circuit may include: a wake-up signal generating circuit operable to generate a wake-up signal for awakening the microcontroller to detect connection of the charging cordset to the receptacle; and a connection circuit configured to conduct through the pin in order to enable the wake-up signal generating circuit to generate the wake-up signal. 
     One non-limiting aspect of the present invention contemplates the wake-up signal generating circuit being configured to generate the wake-up signal as a pulsed wake-up signal. 
     One non-limiting aspect of the present invention contemplates a duration of the pulsed wake-up signal being less than a signal duration needed to awaken the microcontroller. 
     One non-limiting aspect of the present invention contemplates a latching circuit being configured to elongate the duration of the pulsed wake-up signal to at least equal the signal duration needed to awaken the microcontroller. 
     One non-limiting aspect of the present invention contemplates the signal duration needed to awaken the microcontroller being at least 50 ms. 
     One non-limiting aspect of the present invention contemplates a duration of the pulsed wake-up signal being less than 50 ms. 
     One non-limiting aspect of the present invention contemplates the wake-up signal generation circuit being configured to include a capacitor operable to set a duration of the pulsed wake-up signal, wherein a capacitance of the capacitor less than 150 nF. 
     One non-limiting aspect of the present invention contemplates the connection circuit being operable between a first state and a second state, the first state corresponding with the connection circuit consuming a first amount of current and the second state corresponding with the connection circuit consuming a second amount of current where the second amount of current is greater than the first amount. 
     One non-limiting aspect of the present invention contemplates the connection circuit being operable between the first and second state according to controlling signals received from the microcontroller, the microcontroller controlling the connecting circuit to the first state upon determining disconnection of the cordset and to the second state upon determining connection of the cordset. 
     One non-limiting aspect of the present invention contemplates the first amount of current being less than 150 uA. 
     One non-limiting aspect of the present invention contemplates a proximity detection circuit for use in awakening a microcontroller to detect connection of a charging cordset to a vehicle charging system. The proximity detection circuit may include: a pulse signal generating circuit operable to generate a single-pulsed signal for use in awakening the microcontroller from a sleep state to an active state upon connection of the charging cordset to the vehicle charging system; and a connection circuit configured to enable the pulse signal generating circuit to generate the single-pulsed signal upon connection of the charging cordset to the vehicle charging system. 
     One non-limiting aspect of the present invention contemplates a latching circuit being configured to elongate the single-pulsed signal into a wake-up signal sufficient to awaken the microcontroller. 
     One non-limiting aspect of the present invention contemplates the pulse signal generating circuit being configured to include a capacitor operable to set a duration of the single-pulsed signal. 
     One non-limiting aspect of the present invention contemplates a capacitance of the capacitor being less than 150 nF. 
     One non-limiting aspect of the present invention contemplates the connection circuit including a voltage divider connected to the pulse generating circuit at a connection node, the voltage divider providing a first voltage at the connection node when the cordset is disconnected and a second voltage when the cordset is connected where the pulse generating circuit requires the second voltage in order to generate the single-pulsed signal. 
     One non-limiting aspect of the present invention contemplates the connection node coinciding with a terminal of the receptacle used to receive a proximity pin of the cordset, wherein the voltage divider is configured to conduct through the pin in order to provide the second voltage. 
     One non-limiting aspect of the present invention contemplates proximity detection circuit for use in awakening a microcontroller from a sleep state to an active state in order to detect connection of a charging cordset to a vehicle charging system. The proximity detection circuit may include: a pulse signal generating circuit operable to generate a first signal having a first duration; a latching circuit operable to process the first signal into a second signal having a second duration, the second duration sufficient for awakening the microcontroller from the sleep state to the active state; and a connection circuit configured to enable the pulse signal generating circuit to generate the first signal upon connection of the charging cordset to the vehicle charging system. 
     One non-limiting aspect of the present invention contemplates the first duration being insufficient to awaken the microcontroller from the first state to the second state. 
     One non-limiting aspect of the present invention contemplates the connection circuit conducting though a pin of the cordset in order to enable the pulse signal generating circuit. 
     One non-limiting aspect of the present invention contemplates the connection circuit including a voltage divider connected to the pulse generating circuit at a connection node, the voltage divider providing a first voltage at the connection node when the cordset is disconnected and a second voltage when the cordset is connected, wherein the pulse generating circuit requires the second voltage in order to generate the first signal and wherein the connection circuit consumes less than 150 uA through the voltage divider when providing the first voltage at the connection node. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is pointed out 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 referring to the following detailed description in conjunction with the accompany drawings in which: 
         FIG. 1  functionally illustrates logical elements associated with a vehicle power system in accordance with one non-limiting aspect of the present invention. 
         FIG. 2  schematically illustrates a proximity detection circuit in accordance with one non-limiting aspect of the present invention. 
         FIG. 3  illustrates a current path through a connection and wake-up signal generating circuits when a cordset is disconnected in accordance with one non-limiting aspect of the present invention. 
         FIG. 4  illustrates current paths through the connection and wake-signal generating circuits when the cordset is initially connected in accordance with one non-limiting aspect of the present invention. 
         FIG. 5  illustrates a pulsed signal output from of the wake-up signal generating circuit in accordance with one non-limiting aspect of the present invention. 
         FIG. 6  illustrates a pulsed signal output from a latching circuit in accordance with one non-limiting aspect of the present invention. 
         FIG. 7  illustrates current paths through the connection and wake-signal generating circuits when the cordset is connected and additional resistance is added in accordance with one non-limiting aspect of the present invention 
     
    
    
     DETAILED DESCRIPTION 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to 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, specific 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  functionally illustrates logical elements associated with a vehicle power system  10  in accordance with one non-limiting aspect of the present invention. The vehicle power system  10  is shown and predominately described for use within an electric vehicle, hybrid electric vehicle, or other vehicle  12  having a high voltage battery  14  or other energy source operable to provide energy sufficient for use by an electric motor  16  to drive the vehicle  12 . The vehicle  12  may include an on-board charger  20  to facilitate charging the high voltage battery  14  with current delivered through a cordset  22  used to connect the on-board charger to a wall charger or other charging station (not shown). The cordset  22  may used to deliver current through a cable having a terminal (not shown) at one end adapted for receipt within a receptacle or outlet (not shown) associated with the on-board charger  20 . U.S. Pat. No. 7,878,866, entitled Connector Assembly for Vehicle Charging, the disclosure of which is hereby incorporated by reference in its entirety herein, discloses a cordset  22  and receptacle arrangement that may be used in accordance with the present invention. 
     The on-board charger  20  may include electronics or other elements operable to control and manage current flow used to support charging related operations for the high voltage battery  14 , and optionally, to support charging or otherwise powering a low voltage battery  24 , one or more vehicle subsystem  26 , and/or other electronically operable elements included within the vehicle  12 . The low voltage battery  24  may be included to support powering vehicle systems  26  that operate at voltages lower than the electric motor  16 , such as but not limited to remote keyless entry systems, heating and cooling systems, infotainment systems, braking systems, etc. In addition to being charged with energy provided through the cordset  22 , one or more of the high and low voltage batteries  14 ,  24  and vehicle subsystems  26  may be operable to power each other and/or to be powered with energy generated by the electric motor  16 . 
     The low voltage battery  24 , for example, may be operable to provide energy sufficient for use by a lower voltage power source  30 . The lower voltage power source  30  may be operable to regulate current from the low voltage battery  24  for use with one or more of the vehicle subsystems  26  and/or the on-board charger  20 . A controller  32  may be included to facilitate executing logical operations and undertaking other processing requirements associated with controlling the on-board charger and/or controller system within the vehicle  12  (optionally, one or more of the elements may include their own controller or processor). For exemplary purposes, the terms ‘lower,’‘low’, and ‘high’ are used to differentiate voltage levels respectively coinciding with approximately 5 VDC, 12 VDC, and 200 VDC, which are commonly used within vehicles to support the operation associated with each of the corresponding energy sources. This is done without intending to unnecessarily limit the scope and contemplation of the present invention as the present invention fully contemplates the energy sources having the same or different voltage levels and/or current production/generation capabilities. 
     A proximity detection circuit  36  may be included in accordance with one non-limiting aspect of the present invention to facilitate a current conservative configuration operable to facilitate registering connection of the cordset  22  to the on-board charger  20  while the controller is in the sleep or inactive state. The proximity detection circuit  36  may be operable to transition the controller  32  from the sleep state to the active state, optionally while consuming less than 50-150 uA. This may be helpful in allowing the controller  32  to remain in a low energy consumption state (e.g., where the controller  32  is unable to detect connection of the cordset  22  or perform other operations) in order to limit the amount of consumed energy while still allowing the controller  32  to be awoken to perform its prescribed operations once the cordset  22  is connected or some other event takes places (the other events may relate to other triggering operations associated with capabilities that are unavailable while the controller  22  is in sleep mode). 
       FIG. 2  schematically illustrates the proximity detection circuit  36  in accordance with one non-limiting aspect of the present invention. The proximity detection circuit  36  is intended to describe the operation of the circuit related elements (switches, resistors, capacitors, diodes, etc.) shown in  FIG. 2 . The values assigned to these elements and the described use of the elements is not intended to necessarily require that value/element or that the same is part of a dedicated circuit. Rather, the circuit elements may be part of any one or more of the logical elements shown in  FIG. 1 , i.e., some or all of the illustrated circuit components may be included in some or all of the on-board charger  20 , the lower voltage power source  30 , the vehicle subsystems  26 , the controller  32 , the motor  16 , etc. While multiple circuit elements are shown to achieve certain results, the present invention fully contemplates the use of other circuit elements to achieve similar results, particularly the use of other current conservative elements. 
     The proximity detection circuit  36  is shown to be configured to operate with a constant 5 VDC power supply (KA5V), which may be provided by the lower voltage power source  30 . The constant 5 VDC may be used to power switches and bias other elements of the circuit  36  while the controller is in either one of the sleep and/or active states. The configuration shown in  FIG. 2  relies on the 5 VDC to power a connection circuit  40 , a wake-up signal generating circuit  42 , and an optional latching circuit  44 . The connection generating circuit  40  may be configured to generate a signal, such as a voltage change, suitable for use in prompting the wake-up signal generating circuit  42  to output a pulsed signal for use in awakening the controller  32 . In the event a duration/length of the pulsed signal is less than a duration needed to awaken the controller  32 , the latching circuit  44  may be used to elongate the pulse signal, or to otherwise process it, into a signal sufficient to transition the controller  32  from the sleep state to the active state. Once the controller  32  is awoken, it may be configured to monitor a voltage at a PROX_D1 node to determine connection of the cordset  22  and an optional analog to digital component (ADC) may be used to support other software processing based on measured voltage. 
       FIG. 3  illustrates a current path (arrowed lines) through the connection and wake-up signal generating circuits  40 ,  42  when the cordset  22  is disconnected. The controller  32  presumably is in the sleep state at this point due to a prior shutdown event that transitioned the controller  32  to the sleep state upon detection of the PROX_D1 value indicating disconnection of the cordset  22 . The controller  32  may be in the active state to complete or perform other operations or in the process of transitioning to the sleep state while the illustrated current path is active. When the cordset  22  is disconnected, switch Q 1  is open, Q 19  is closed, Q 12  is open, switch Q 8  is open, a PROX voltage set by the controller is zero, and a terminal  48  of the vehicle-based receptacle used to receive a proximity pin (not shown) of the cordset  22  is empty. This results in the illustrated current path through Q 19 , R 130 , and R 33  of the connection circuit  40 . The wake-up signal generating circuit  42  has no current path since a voltage on either side of the capacitor C 39  is constant. 
       FIG. 4  illustrates current paths (arrowed lines) through the connection and wake-signal generating circuits  40 ,  42  when the cordset  22  is initially connected. The controller, unless previously awoken, is in the sleep state at least for a short period of time after connection of the cordset  22 . Connection of the cordset  22  results in the proximity pin  49  being inserted within the corresponding terminal receptacle  48  and becoming part of the connection circuit  40 . The inserted pin  49  conducts current through the terminal  48  such that resistor R 34  becomes connected to a connection node  50  between R 130  and R 33 , effectively lowering a voltage at the connection node  50 . The lowered connection node voltage reduces the voltage on one side of the capacitor C 39 , and thereby, initiates a charging operation of the capacitor C 39  with energy from the 5 VDC power supply. The flow of current through the emitter and base of switch Q 1  caused by charging of the capacitor C 39  transitions switch Q 1  from an open to a closed state, resulting in approximately a 5V pulse at a PROX_SET node associated with the collector of switch Q 1 . 
       FIG. 5  illustrates a pulsed signal output  54  from the PROX_SET node of the wake-up signal generating circuit  42 . The pulsed signal  54  may be characterized as a single pulsed signal having a duration from time T 1  to time T 2  wherein time T 1  corresponds with the charging of capacitor C 39  and time T 2  corresponds with capacitor C 39  becoming charged. The duration between time T 1  and time T 2  is proportional to a capacitance of the capacitor C 39  and can be varied by changing the capacitance. One non-limiting aspect of the present invention contemplates capacitor C 39  having a capacitance of less than 150 nF, such as 100 nF, in order to limit its size (a larger capacitor may be more expensive and have a slower rise time). Of course, the present invention fully contemplates the use of any sized capacitor and is not intended to be necessarily limited to the noted capacitances. 
     The duration of the single pulsed signal output at the PROX_SET node may be less than a duration needed to awaken the controller  32 . The PROX_SET signal  54  is illustrated to have a duration of less than 50 mS (shown as 25 mS) whereas the controller  32  may be of the type requiring at least a 50 mS pulse in order to transition from the sleep state to the active state. In order to reduce costs and achieve desired signal rise times, one non-limiting aspect of the present invention contemplates including the latching circuit  44  to elongate the PROX_SET signal  54  instead of simply increasing the size of capacitor C 39 .  FIG. 6  illustrates a pulsed signal output  56  from the latching circuit  44  to awaken the controller  32 . The pulsed signal  56  has a longer duration (shown to be up to time T 3 ) than a time Tw needed to awaken the controller  32 . 
     As shown in  FIG. 2 , the PROX_SET pulse signal  54  may be output from the PROX_SET node to an input of the latching circuit  44 . The latching circuit  44  may then elongate the signal or perform other processing to generation a WAKE_UP signal output  56  to the controller  32 . Once awoken, the controller  32  may set a LATCH_RESET signal  60  to reset the latching circuit  44  for generation of subsequent WAKE-UP signals  56 . The awoken controller  32  may then determine connection of the cordset  22  based the voltage at the connection node. Optionally, the controller  32  may be configured to support two or more connection states, such as to support connection detection voltages required by Society of Automotive Engineer (SAE) J1772 and International Electrotechnical Commission (IEC) 51851. These connection states may be supported by the controller  32  controlling the additional of resistor R 177  to the current path through the connection circuit  40 . 
       FIG. 7  illustrates the SAE J1772 connection status by way of resistor R 177  being added to the current path with the controller  32  providing a PROX signal to a PROX input to activate switches Q 12  and Q 8 . The PROX signal may be provided by the controller  32  immediately after awakening according to prior software programming. The addition of resistor R 177  changes the voltage at the connection node to meet the SAE J1772 requirement. The resulting voltage change then induces a discharging of the capacitor C 39  through the 5 VDC power source of the wake-up signal generating circuit  42  in the illustrated current path. In the event the IEC 51851 standard is used, the resistor R 177  is not connected in parallel with resistor R 130  and the current path through the 5 VDC power source of the wake-up signal resulting from discharging of the capacitor C 39  is delayed until removal of the proximity pin from the terminal. 
     Once the proximity pin  49  is removed from the terminal  48 , the controller  32  detects the corresponding voltage change at the connection node  50  and automatically transitions to the sleep state. The transitioning to the sleep state may include removing resistor R 177  from the current path with deactivation of the switch Q 8 . The removal of resistor R 177  can be done to reduce current consumption (quiescent current) of the connection circuit  40  to less than 150 uA, and preferably less than 100 uA, depending on the component values remaining in the current path. The ability to control the quiescent current may be beneficial in achieving desired proximity (connection) detection while minimizing energy consumption. 
     As supported above, the present invention may be configured to: wake up on falling edge of proximity; wake up on edge transitions lower than 1V; achieve low quiescent current operation during sleep mode; facilitate latched wake up to meet minimum startup current requirements of the system; allows for system sleep mode with proximity signal continuously applied; provide selectable SAE/IEC or other settings; automatically switch from SAE to IEC mode during sleep to lower quiescent current consumption; automatic switch from SAE to IEC also allows for improved low voltage wake up response; enter sleep mode (e.g., using controller  32 ) with proximity applied (steady state); detect change in proximity level as low as 800 mV; and transition at any voltage levels (e.g., 5V to 4V or 3V to 1V etc.). 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.