Abstract:
In one implementation, the method for processor based automated testing of ground fault interrupt circuit for electric vehicle supply equipment is provided. In one implementation the method includes providing a simulated ground fault signal to a ground fault interrupt circuit and detecting at a processor that the ground fault interrupt circuit sensed the simulated ground fault signal. The method further includes commanding from the processor a utility power contactor to close while the ground fault interrupt circuit is disabling closing of the contactor and verifying the utility power contactor is not closed in response to commanding the utility power contactor to close.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of PCT/US2011/048298 by Flack, entitled GROUND FAULT INTERRUPT AUTOMATIC TEST METHOD FOR ELECTRIC VEHICLE, filed on 18 Aug. 2011, herein incorporated by reference in its entirety. 
         [0002]    PCT/US2011/048298 claims the benefit of U.S. Provisional Application 61/374,612, entitled GROUND FAULT INTERRUPT AUTOMATIC TEST METHOD FOR ELECTRIC VEHICLE, by Albert Flack, filed 18 Aug. 2010, hereby incorporated by reference in its entirety, and 
         [0003]    PCT/US2011/048298 is continuation of PCT Application PCT/US2011/032576, entitled GROUND FAULT INTERRUPT CIRCUIT FOR ELECTRIC VEHICLE, by Albert Flack, international filing date 14 Apr. 2011, which claims the benefit of U.S. Provisional Application Ser. No. 61/324,296, entitled GROUND FAULT INTERRUPT CIRCUIT FOR ELECTRIC VEHICLE, by Albert Flack, filed Apr. 14, 2010, and claims benefit of 61/374,612, entitled GROUND FAULT INTERRUPT AUTOMATIC TEST METHOD FOR ELECTRIC VEHICLE, by Albert Flack, filed 18 Aug. 2010, and claims benefit of 61/324,293, entitled PILOT SIGNAL GENERATION CIRCUIT by Albert Flack, filed Apr. 14, 2010, all herein incorporated by reference in their entireties. 
         [0004]    The present application is a continuation-in-part of U.S. application Ser. No. 13/651,417, entitled GROUND FAULT INTERRUPT CIRCUIT FOR ELECTRIC VEHICLE, by Flack et al., filed 14 Oct. 2012, which is a continuation of PCT Application PCT/US2011/032576, entitled GROUND FAULT INTERRUPT CIRCUIT FOR ELECTRIC VEHICLE, by Albert Flack, international filing date 14 Apr. 2011, which claims the benefit of U.S. Provisional Application Ser. No. 61/324,296, entitled GROUND FAULT INTERRUPT CIRCUIT FOR ELECTRIC VEHICLE, by Albert Flack, filed Apr. 14, 2010, and claims benefit of 61/374,612, entitled GROUND FAULT INTERRUPT AUTOMATIC TEST METHOD FOR ELECTRIC VEHICLE, by Albert Flack, filed 18 Aug. 2010, and claims benefit of 61/324,293, entitled PILOT SIGNAL GENERATION CIRCUIT by Albert Flack, filed Apr. 14, 2010, all herein incorporated by reference in their entireties. 
     
    
     BACKGROUND 
       [0005]    One way to charge an electric vehicle is to supply the vehicle with power so that a charger in the vehicle can charge the battery in the vehicle. If there is a ground fault in the electrical system in the car when electrical power is supplied, and someone touches car while grounded, that person could be shocked. A ground fault interrupt is typically provided to prevent this. If the ground fault interrupt is not functioning properly, however, risk of shock could still be present. 
         [0006]    Thus, what is needed is a ground fault interrupt test to ensure the ground fault interrupt functions properly. Moreover, what is needed is an automated test. 
       SUMMARY 
       [0007]    In one implementation, a method for processor based automated testing of ground fault interrupt circuit for electric vehicle supply equipment is provided. In one implementation the method includes providing a simulated ground fault signal to a ground fault interrupt circuit and detecting at a processor that the ground fault interrupt circuit sensed the simulated ground fault signal. The method further includes commanding from the processor a utility power contactor to close while the ground fault interrupt circuit is disabling closing of the contactor and verifying the utility power contactor is not closed in response to commanding the utility power contactor to close. 
         [0008]    In some implementations the commanding of the utility power contactor to close may include commanding the utility power contactor to close in response to the processor detecting that the ground fault interrupt circuit sensed the simulated ground fault signal. 
         [0009]    In some implementations the method may further include receiving a request for charging via a pilot signal and commanding the utility power contactor to close in response to the request for charging on the pilot signal prior to resetting the ground fault interrupt circuit. 
         [0010]    In some implementations the method may further include resetting the ground fault interrupt circuit while commanding the utility power contactor to close and verifying with the processor that the contactor closes after the resetting of the ground fault interrupt circuit while the processor is commanding the utility power contactor to close. 
         [0011]    In some implementations the method may further include oscillating a pilot signal, receiving a request for charging via the oscillating pilot signal, and commanding the utility power contactor to close in response to the request for charging on the pilot signal while the ground fault interrupt circuit disables closing of the contactor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The features and advantages of the present invention will be better understood with regard to the following description, appended claims, and accompanying drawings where: 
           [0013]      FIG. 1  shows a schematic view of a cable to connect utility power to an electric vehicle (not shown) along with some associated circuitry. 
           [0014]      FIG. 2  shows an enlarged view schematic drawing of the GFI circuit of  FIG. 1 . 
           [0015]      FIG. 3  shows a schematic view of a contactor control circuit. 
           [0016]      FIG. 4  shows an enlarged more complete schematic of the pilot circuitry shown in partial schematic in  FIG. 1 . 
           [0017]      FIG. 5  is a partial schematic showing a microprocessor, which may be used to govern the output of the GFI circuit. 
           [0018]      FIG. 6  shows a simplified plot of an example of possible charge accumulation by the double stage filter leading to a fault detection by the comparator. 
           [0019]      FIG. 7  is a simplified schematic diagram of a pilot signal generation circuit in accordance with one possible embodiment. 
           [0020]      FIG. 8  is an example timing diagram of signals for the pilot circuit of  FIG. 7 . 
           [0021]      FIGS. 9 and 10  are simplified timing diagrams illustrating implementations for automatic GFI testing with no fault ( FIG. 9 ) and with a fault ( FIG. 10 ). 
       
    
    
     DESCRIPTION 
       [0022]    The below discussion with reference to  FIGS. 1-6  illustrate a possible ground fault interrupt circuit and associated circuitry for use with the methods of  FIGS. 7 and 8 .  FIGS. 9 and 10  provide implementations of ground fault interrupt automatic testing. 
         [0023]    
       FIGS. 1-8 
     
         [0024]    The below discussion with reference to  FIGS. 1-6  illustrate a possible ground fault interrupt circuit and associated circuitry for use with the methods of  FIGS. 7 and 8 . 
         [0025]      FIG. 1  shows a schematic view of a cable  100  to connect utility power to an electric vehicle (not shown) along with some associated circuitry. In the embodiment of  FIG. 1 , the cable  100  contains L 1  and L 2  and ground G lines. The cable  100  connects to utility power at one end  100   u  and to an electric vehicle (not shown) at the other end  100   c.  The electric vehicle (not shown) could have an onboard charger, or, the electric vehicle end  100   c  of the cable  100  could be connected to a separate, optionally free standing, charger (not shown). The separate charger (not shown) would in turn be connected to the electric vehicle for charging onboard batteries, or other charge storage devices. In other embodiments not shown, a charger could be integrated into the cable  100 , if desired. 
         [0026]    GFI Circuit 
         [0027]    
       FIGS. 1-6 
     
         [0028]    The cable  100  contains current transformers  110  and  120 . The current transformer  110  is connected to a ground fault interrupt or GFI circuit  130  which is configured to detect a differential current in the lines L 1  and L 2  and indicate when a ground fault is detected. Contactor  140  may be open circuited in response to a detected ground fault to interrupt utility power from flowing on lines L 1  and L 2  to the vehicle (not shown). 
         [0029]      FIG. 2  shows an enlarged view schematic drawing of the GFI circuit  130  of  FIG. 1 . In the embodiment of  FIG. 2 , the GFI circuit  130  is designed to trip in the 5-20 mA range for GFI in accordance with the UL 2231 standard. 
         [0030]    A signal provided by current transformer  110  ( FIG. 1 ) at pins  3  and  4  of the GFI circuit  130  is amplified by op amp  132  to a voltage reference. That voltage reference is filtered by a double stage RC filter  134  to eliminate spurious noise spikes. 
         [0031]    Fault current detected by current transformer  110  ( FIG. 1 ) is converted to voltage by gain amplifier  134  for comparison by comparator  136 . The output of the gain amplifier  132  is filtered prior to being supplied to the comparator  136  with the double stage RC filter  134  to remove spurious noise that could cause nuisance shut downs. Output of comparator  136  is latched with flip-flop  138  so that contactor  140  ( FIG. 1 ) does not close after a fault has been detected. The comparator  136  provides a GFI_TRIP signal output, which is an input to the fault latch  138  to produce a latched GFI_FAULT signal. 
         [0032]    The double stage filter  134  provides a delay so that the shut-off circuit does not immediately shut off if a fault is detected. The double stage filter  134  is a half-wave rectified circuit that allows an incoming pulse width that is less than 50% in some embodiments, or even as small as about 38% in some embodiments, to accumulate over time so that it will charge at a faster rate than it discharges. The double stage filter  134  accumulates charge and acts an energy integrator. Thus, the GFI circuit  130  waits a time period before causing shut down. This is because it is not desirable to have an instantaneous shut down that can be triggered by noise in the lines L 1  or L 2 , or in the GFI circuit  130 . The GFI circuit  130  should trip only if a spike has some predetermined duration. In the embodiment shown, that duration is one to two cycles. 
         [0033]    The filter  134  charges through R 102  and R 103 . When it discharges, it only discharges through R 102 , so it charges more current than it discharges over time. The double stage filter  134  is a half wave rectified circuit due to diode D 25 . 
         [0034]    Diodes D 4  provide surge suppression protection. In typical embodiments, the gain amplifier  132  may actually have surge suppression protection. Despite this, diodes D 4  are added to provide external redundant protection to avoid any damage to the gain amplifier  132 . This redundant protection is significant, because if the  132  gain amplifier is damaged, the GFI protection circuit  130  may not function, resulting in inadequate GFI protection for the system. For example, without the redundant surge suppressing diodes D 4 , if a power surge were to damage the gain amplifier  132  so that it no longer provided output, the GFI circuit  130  would no longer be able to detect faults. Since UL  2231  allows utility power L 1  and L 2  power to be reconnected after a GFI circuit detects a ground fault surge, utility power L 1  and L 2  could conceivably be reconnected after the gain amplifier  132  had been damaged. It is significant to note that the diodes D 4  are connected to the upper and lower reference voltage busses of the circuit, i.e. ground and  3  volts, respectively, so that they can easily dissipate surge current without causing damage to the circuitry. Thus, the redundant surge suppression diodes D 4  provide an additional safety feature for the GFI protection circuit  130 . 
         [0035]      FIG. 3  shows a schematic view of a contactor control circuit  170 . The contactor control circuit  170  opens/closes the contactor  140  ( FIG. 1 ) to disconnect/connect the utility power L 1  and L 2  from/to the vehicle connector  100   c.  As discussed above with reference to  FIG. 2 , the GFI_TRIP signal is output by the comparator  136  and is an input to the fault latch  138  to produce the GFI_FAULT signal. The GFI_FAULT signal output by the fault latch  138  is an input to the contactor control circuitry  170 , shown in  FIG. 3 , used to control the contactor control relay K 1 . The contactor control relay K 1  is used to open/close the contactor  140  ( FIG. 1 ) to disconnect/connect the utility power L 1  and L 2  from/to the vehicle connector  100   c.  The CONTACTOR_AC signal output by the contactor control relay K 1  is connected to the contactor coil  141  ( FIG. 1 ) through pin  1  of the connector  181  ( FIG. 1 ) associated with the utility present circuitry  180  ( FIG. 1 ). 
         [0036]    The GFI_TRIP signal output by the comparator  136  ( FIG. 2 ) is not only provided to the contactor control circuit  170  ( FIG. 3 ), but also is provided as an input to the contactor disable latch  152 , shown in  FIG. 4  to produce a CONTACTOR_FAULT_DISABLE signal.  FIG. 4  shows an enlarged more complete schematic view of the pilot circuitry  150  shown in partial schematic in  FIG. 1 . Additionally, the contactor disable latch  152  ( FIG. 4 ) is an input to the contactor control circuitry  170  ( FIG. 3 ) to control the contactor control relay K 1  ( FIG. 3 ). The CONTACTOR_FAULT_DISABLE signal is used to open the contactor control relay K 1  ( FIG. 3 ), which opens the contactor  140  ( FIG. 1 ) to open/close circuit the utility power L 1  and L 2 . This provides a redundant circuit for this important safety control circuit. Further, it requires the reset of both latches  138  ( FIGS. 2) and 152  ( FIG. 4 ) to reconnect L 1  and L 2  utility power to the vehicle connector  100   c.  This provides further software redundancy for this important safety control circuit. 
         [0037]      FIG. 5  is a partial schematic showing a microprocessor  500 , which may be used to govern the output of the GFI circuit  130  ( FIG. 2 ). Referring to  FIGS. 2 and 5 , the GFI_FAULT output signal from the fault latch  138  is provided as an input at pin  552  to the microprocessor  500 . The microprocessor  500  outputs at pin  538  the GFI_RESET signal to the GFI circuit  130  to control the reset of the GFI circuit  130 , in accordance with a predetermined standard, such as UL  2231 . This may be accomplished by outputting the GFI_RESET signal to the fault latch  138 , and to the CONTACTOR_RESET to the contactor disable latch  152  ( FIG. 4 ). 
         [0038]    Also, the microprocessor  500  may also output at pin  81  the GFI_TEST signal, which causes a GFI test circuit  139  to simulate a ground fault for testing the functionality of the contactor  140  ( FIG. 1 ). The GFI test circuit  139  output AC_ 1  provides a path via pin  2  of the connector  181  to the contactor coil  141  ( FIG. 1 ) to exercise the contactor  140 . 
         [0039]    Additionally, the microprocessor  500  provides a CONTACTOR_CLOSE signal output to the contactor close circuit to close the contactor control relay K 1  ( FIG. 3 ). 
         [0040]    Further, the microprocessor  500  may provide signals to the pilot circuit, such as the PILOT_PWM discussed below with reference to  FIGS. 7 and 8 . 
         [0041]      FIG. 6  shows a simplified plot  600  of an example of possible charge accumulation by the double stage filter  134  ( FIG. 2 ) leading to a fault detection by the comparator  136  ( FIG. 2 ). Referring to  FIGS. 2 and 6 , since the double stage filter  134  discharges slower than it charges, several successive current pulse detections  601 ,  602 , and  603  would be required to cause sufficient charge to accumulate a voltage level that would cause the comparator to indicate a GFI TRIP. Thus, faults by spurious noise can be minimized. 
         [0042]    In this simplified example plot, a 1.5 volts pulse of about 38% of the duty cycle for three successive cycles causes sufficient charge to accumulate a GFI TRIP signal. Other embodiments are possible by appropriate selection of the R 102 , R 103 , and C 51 . 
         [0043]    Pilot Signal Circuit 
         [0044]      FIGS. 1 ,  4 ,  5 , and  7 - 8   
         [0045]    In some embodiments a PILOT signal in accordance with the SAE J-1772 standard is provided. The SAE-J1772 standard, incorporated herein by reference in its entirety, requires precise voltage levels on the PILOT signal, which communicates a charge current command from the electric vehicle supply equipment system, illustrated in  FIGS. 1-5 , to the electric vehicle. A certain level of error is allowed but more precise signal sourcing provides a more confident operational profile. In various embodiments, the pilot signal generation circuit  150  generates a clean and precise PILOT signal. The pilot signal generation circuit  150  provides the PILOT signal via the connector  100   c  at the vehicle end of the cable  100 . The pilot signal communicates information between the battery charger (not shown) in the vehicle and the electric power supply control system illustrated in  FIGS. 1-5 . 
         [0046]      FIG. 7  is a simplified schematic diagram of a pilot signal generation circuit  155  in accordance with one possible embodiment.  FIG. 8  is an example timing diagram of signals for the pilot circuit  155  of  FIG. 7 . In the embodiment of  FIG. 7 , the PILOT signal is to be sourced at a value of from +12.0 Volts to −12.0 Volts in a pulse width modulated (PWM) square wave with a frequency of 1,000 Hz. A logic level pulse width modulated square wave PILOT_PWM signal controls the duty cycle and frequency. In the embodiment of  FIG. 7  and the timing diagram illustrated in  FIG. 8 , the PILOT_PWM signal is a logic level signal of 0-3.3 Volts. The logic level signal PILOT_PWM may be any other voltage(s) depending on the embodiment. An absolute reference voltage V_REF provides the precision voltage value for the circuit  155 . In this example V_REF is +3.0V. Operational amplifiers  731  and  732 , and resistors R 30 -R 32  and R 116 -R 117  are used in conjunction with two Field Effect Transistors or FETs  701  and  702  to generate the final PILOT signal. In this example, the typical resistance values for R 30 -R 32 , R 116 , and R 117  are given in ohms as 100K, 1.00K, 25.0K, 10.0K, and 25.0K, respectively, but the values can be altered to change the circuit  155  performance. In other embodiments, the transistors  701  and  702  may be another type, such as bipolar for example. 
         [0047]    As shown in  FIG. 7 , the pilot signal generation circuit  155  has a first operational amplifier  731  having a non-inverting input connected via a first resistor R 116  to receive a source reference voltage V_REF. The output  731   c  is directly connected to the inverting input  731   b  of the first operational amplifier. A second operational amplifier  732  has its non-inverting input  732   a  connected via a second resistor R 32  to receive the source reference voltage V_REF. The non-inverting input  732   a  is also connected in parallel to ground or other reference voltage via resistor R 30 . The inverting input  732   b  is connected via a resistor R 117  to the output  731   c  of the first operational amplifier. The output  732   c  connected via a resistor R 33  to the non-inverting input  732   b  of the second operational amplifier  732 . 
         [0048]    Furthermore, the pilot signal generation circuit  155  has a first transistor  701  with its gate  701   g  connected to receive a logic level pulse width modulated control signal PILOT_PWM. The logic level pulse width modulated control signal PILOT_PWM may be supplied by the microprocessor  500  ( FIG. 5 ). The drain  701   d  is connected to the non-inverting input  731   a  of the first operational amplifier  731 , and the source  701   s  is connected to ground or other reference voltage. A second transistor  702  has a gate  702   g  connected to the drain  701   d  of the first transistor  701 . The drain  702   d  of the second transistor  702  is connected to the non-inverting input  732   a  of the second operational amplifier  732 , and the source  702   s  is connected to ground or other reference voltage. 
         [0049]    Referring again to  FIGS. 7 and 8 , the PILOT_PWM signal may be a digital signal created by an external control source, such as a microprocessor  500  ( FIG. 5 ). The logic level signal PILOT_PWM controls operation of the pilot signal generation circuit  155 . 
         [0050]    When the PILOT_PWM signal is low at the gate  701   g  of transistor  701 , transistor  701  is open from drain  701   d  to source  701   s.  The voltage on transistor drain  701   d  then feeds into transistor gate  702   g  causing it to turn on, shorting its drain  702   d  to source  702   s.  In this condition, the input  731   a  of the first operational amplifier  731  has a high impedance +3.00 Volts applied to it, which is then buffered by the second operational amplifier  732  to provide a low impedance signal at +3.00 Volts for the second operational amplifier  732  to use as a signal source. Input  732   a  of the second operational amplifier  732  is held at 0 Volts by transistor  702 . As a result, the output of  732   c  of the second operational amplifier  732  then has a negative voltage proportional to the gain of the second operational amplifier  732  circuit, specified by the ratio of R 33  to R 117 ; in this case, −12.00 Volts. 
         [0051]    When the PILOT_PWM signal is high,  701  is shorted from drain  701   d  to source  701   s.  The 0 Volts on drain  701   d  of transistor  701  then feeds into gate  702   g  of transistor  702  causing it to be open from drain  702   d  to source  702   s.  In this condition, input  731   a  the first operational amplifier  731  has 0 Volts applied to it, which is then buffered by the first operational amplifier  731  to provide 0 Volts for the second operational amplifier  732  to use as a signal source at input  732   b.  Input  732   a  of the second operational amplifier  732  is fed by the +3.00 Volts reference V_REF and differentially amplified against the 0 Volts signal provided from output  731   c.  As a result, the output  732   c  of the second operational amplifier  732  has a positive voltage proportional to the gain of the second operational amplifier  732  circuit, specified by R 33 , R 117 , R 30  and R 32 ; in this case, +12.00 Volts. 
         [0052]    Thus, by use of this circuit  155 , a high or low logic level signal PILOT_PWM of imprecise voltage will provide a precise +12 Volt to −12 Volt square wave output suitable for use as the control communication signal source PILOT for the SAE-J1772 standard signal generation. Accuracy is only limited by component selection. Because this circuit  155  is absolute reference and amplifier regulated, the +/−12 volt signals are extremely accurate with no undesired component losses. This supports and enhances the application of the SAE J-1772 standard for reading the communication level control voltages without errors. 
         [0053]    If the onboard charger sees a signal amplitude too low or too high, or improper frequency or pulse width within an expected range, it will shut off because it will assume that the integrity of the connection is bad. So it is important to have a precise PILOT signal. 
         [0054]    In various embodiments of the pilot signal generation circuit  155 , the operational amplifier  731  is configured to buffer the input  731   a  to the output  731   c.  The operational amplifier  732  is configured with resistors R 30 , R 32 , R 33 , and R 117  as a differential amplifier. The transistor  701  is connected to the operational amplifier  731  to shunt the source reference voltage V_REF at the input  731   a  of the operational amplifier  731 . The transistor  702  is connected to the operational amplifier  732  to shunt the source reference voltage V_REF at the input  732   a  of the operational amplifier  732  in response to a voltage level at the input  731   a  of the operation amplifier  731 . 
         [0055]    Thus, the pilot signal generation circuit  155  is configured to receive a logic level pulse width modulated signal PILOT_PWM at the input  701   g  of the transistor  701  and to provide a pulse width modulated bipolar signal PILOT at precision voltage levels at the output  732 C of the second operational amplifier  732 . 
         [0056]    In various embodiments, the pilot generation circuit  155  is able to provide an output PILOT signal with precise voltage levels to within about 1% at +/−12 Volts. 
         [0057]    The voltage of the PILOT signal will indicate the status of the connection between the cable  100  and the vehicle (not shown). In this example, a PILOT signal of +12 Volts indicates that the connector  100   c  is disconnected from the vehicle and not stowed. Optionally, a PILOT signal voltage of +11 Volts may be used to indicate that the connector  110   c  is stowed, at a charging station, for example. A PILOT signal voltage of +9 Volts indicates that the vehicle is connected. A PILOT signal voltage of +6 Volts indicates that the vehicle is charging without ventilation. A PILOT signal voltage of +3 Volts indicates that the vehicle is charging with ventilation. A PILOT signal voltage of 0 Volts indicates that there is a short or other fault. A PILOT signal voltage of −12 Volts indicates that there is an error onboard the vehicle. 
         [0058]    A pilot detection circuit  157  within the pilot circuit  150  detects the voltages, generates, and provides a PILOT_DIGITAL signal to the microprocessor  500  ( FIG. 5 ). The pilot detection circuit  157  also generates and provides a PILOT_MISSING_FAULT signal to the microprocessor  500  ( FIG. 5 ). In response, the microprocessor  500  controls the connection of the utility power L 1  and L 2 . For example, the microprocessor  500  can set the CONTACTOR CLOSE signal, discussed above, to cause the control contactor  170  to open the contactor  140  if a PILOT_MISSING_FAULT is detected. 
         [0059]    Ground Fault Auto Test 
         [0060]    
       FIGS. 9 and 10 
     
         [0061]    In order to provide the capability of auto-restart, there should also be an automatic GFI test. The automatic GFI test function can best be performed at the beginning of each START or RESTART charge cycle. If the test is passed then the charge cycle can proceed. If the GFI test fails then the charge cycle is disallowed. 
         [0062]    Normally the GFI test checks the entire sense and control circuits, including the ability of the contactor  140  ( FIG. 1 ) ability to open. This would normally require that the GFI test first close the contactor  140  ( FIG. 1 ) and then test the GFI circuit  130 ( FIG. 1 ), which should result in the contactor  140  ( FIG. 1 ) opening. This process would subject the On Board Charger (OBC)(not shown) of the electric vehicle (not shown) to the application and removal of AC power. Also, the application of power could overshadow the test if an additional external current leakage was induced during the application of AC power to the OBC. 
         [0063]      FIGS. 9 and 10  are simplified timing diagrams illustrating implementations for automatic GFI testing with no fault ( FIG. 9 ) and with a fault ( FIG. 10 ) Note that steps  1  thru  5  on the  FIGS. 9 and 10  are identical. From step  6  on, the methods are different. 
         [0064]    On one implementation of the new approach to the GFI test is to apply AC power to the electric vehicle service equipment (EVSE) or charger at step  1  and then connect the charger plug to the electric vehicle (EV) at step  2 . Once the EVSE senses the connected status (9V Pilot level), it first verifies that the contactor is not closed at step  3 , which may be by performing a contactor health check. This of course would have been the natural state at this point. It also verifies that the GFI_TRIP signal ( FIG. 2 ) is not in the disabled state at step  4 . The GFI test is then applied at step  5 , presenting a false GFI current signal to the sense circuit. This small current trips the GFI control circuit at step  6  which is then sensed by the CPU or other processor  500  ( FIG. 5 ). If this succeeds then the basic sense and disable portion of the system is verified to be functional. The next step of the process is to try to close the breaker by CPU  500  ( FIG. 5 ) control, which will prove that the contactor  140  ( FIG. 1 ) is or is not able to be closed. Since this aspect of the test overlaps the subsequent charge cycle function of closing the contactor  140  ( FIG. 1 ), they may be combined as a smooth single process. 
         [0065]    The EVSE continues to complete the test and provide power to the EV as follows. The Pilot signal begins oscillating at step  7  and the OBC then sets the amplitude to 6 (or 3) volts at step  8 . The CPU commands the contactor to close at step  9  and monitors the next stage of the GFI ENABLE signal at  10  which is still active (in the disabled state). If the next stage is seen to not be able to close the contactor then the final control element of the GFI has been verified. The GFI circuit is reset at step  11  and the contactor driver signal is seen to go high at step  12  verifying that the contactor will close. The contactor subsequently closes at step  13  and is verified at step  14 , such as by performing a contactor health check. Normal charging then proceeds. 
         [0066]    It is significant to note that the final circuit verification will take about five microseconds and as such will not have time to actually close the contactor relay (which takes five milliseconds) and therefore not be able to close the contactor (ten milliseconds), so no power will ever leave the EVSE during this test if it fails. 
         [0067]    Referring to  FIG. 10 , if the signal is seen after step  5  to enable the contactor then the GFI test is determined to have failed. The CPU will stop the test process and go to the fault state at  6 A where the OBC is informed about the fault by setting the Pilot to −12V. After the fault is indicated to the OBC as an EVSE fault, the Pilot signal is returned to the high state at  7 A. At some time later the charge plug is disconnected from the EV, resetting the fault at  8 A. 
         [0068]    A manual version of this test can be implemented at any time with or without an EV. 
         [0069]    In one implementation of the manual GFI test while charging, when the EV is in a charging condition, is to push the control buttons for the manual test start. The contactor is already closed so the EVSE turns on the GFI test circuit which applies the trigger current to the utility line. The GFI sense circuit will trip within  30  mSec which will force open the contactor. The test fails if the contactor is not sensed to open by reading the control line feedback signal, the CONTACTOR_ON signal (at a test point if desired). 
         [0070]    In one implementation of the manual GFI test while not connected to an EV, is to push the control buttons for the manual test start. The sequence will follow a similar pattern as with the auto restart sequence but the voltage on the pilot will remain at +12Vdc and not go to +9VDC. This will insure by hardware that the contactor will not close. The trip current is actuated and the GFI trip function can be then traced by reading the GFI_FAULT signal (at a test point if desired). This is a partial verification of the total circuit. The contactor close function can be implemented by taking the Pilot signal to −12VDC through DSP control. This will allow contactor closure but that could be dangerous since it may happen when the charge plug is out in the open. 
         [0071]    It is worthy to note that any reference to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in an embodiment, if desired. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
         [0072]    The illustrations and examples provided herein are for explanatory purposes and are not intended to limit the scope of the appended claims. This disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the spirit and scope of the invention and/or claims of the embodiment illustrated. 
         [0073]    Those skilled in the art will make modifications to the invention for particular applications of the invention. 
         [0074]    The discussion included in this patent is intended to serve as a basic description. The reader should be aware that the specific discussion may not explicitly describe all embodiments possible and alternatives are implicit. Also, this discussion may not fully explain the generic nature of the invention and may not explicitly show how each feature or element can actually be representative or equivalent elements. Again, these are implicitly included in this disclosure. Where the invention is described in device-oriented terminology, each element of the device implicitly performs a function. It should also be understood that a variety of changes may be made without departing from the essence of the invention. Such changes are also implicitly included in the description. These changes still fall within the scope of this invention. 
         [0075]    Further, each of the various elements of the invention and claims may also be achieved in a variety of manners. This disclosure should be understood to encompass each such variation, be it a variation of any apparatus embodiment, a method embodiment, or even merely a variation of any element of these. Particularly, it should be understood that as the disclosure relates to elements of the invention, the words for each element may be expressed by equivalent apparatus terms even if only the function or result is the same. Such equivalent, broader, or even more generic terms should be considered to be encompassed in the description of each element or action. Such terms can be substituted where desired to make explicit the implicitly broad coverage to which this invention is entitled. It should be understood that all actions may be expressed as a means for taking that action or as an element which causes that action. Similarly, each physical element disclosed should be understood to encompass a disclosure of the action which that physical element facilitates. Such changes and alternative terms are to be understood to be explicitly included in the description. 
         [0076]    Having described this invention in connection with a number of embodiments, modification will now certainly suggest itself to those skilled in the art. The example embodiments herein are not intended to be limiting, various configurations and combinations of features are possible. As such, the invention is not limited to the disclosed embodiments, except as required by the appended claims.