Abstract:
Embodiments pertain to devices and systems having simulator circuitry, particularly to simulator circuitry configured to simulate an electric vehicle and test an electric vehicle charger. A test unit is configured to simulate a GFI current via modulator and to simulate electric vehicle loads via switched and combined resistor loads. The test unit provides for reprogramming of the electric vehicle charger via a pilot line. The test unit self-confirms its usability via associating received codes.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a 371 application of International Application No. PCT/US2010/048179 filed Sep. 8, 2010, which claims the benefit of U.S. Provisional Application No. 61/240,577 filed Sep. 8, 2009, and this application also claims the benefit of U.S. Provisional Application No. 61/246,469, filed Sep. 28, 2009, the disclosures of all of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     Embodiments pertain to simulator circuitry, particularly to simulator circuitry configured to simulate an electric vehicle and test an electric vehicle charger. 
     BACKGROUND 
     Methods and apparatuses for simulating an automated battery tester with a fixed resistance load have been proposed. 
     SUMMARY 
     Method and system embodiments include a device configured to simulate an electric vehicle charging system, the device comprising: (a) a charge plug interface; (b) means for simulating pilot line feedback; (c) means for simulating electric vehicle load; and (d) means for simulating a ground fault interrupt current. The means for simulating pilot line feedback may comprise circuitry configured to initiate a pilot voltage drop to confirm readiness to accept energy. The means for simulating electric vehicle load may comprise a plurality of resistor banks, selectable via microcontroller-controlled switches, having a load approximating an expected load of an electric vehicle. The means for simulating a ground fault interrupt current may comprise a modulator circuit comprising a modulator generating a pulse width modulating signal having a microcomputer-controlled duty cycle. 
     Method and system embodiments include a device configured to simulate a ground fault interrupt (GFI) current where the device comprises: (a) a modulator circuit comprising a modulator having a duty cycle of pulse width modulation adjustable via a microprocessor input, the modulator circuit configured to provide linear adjustments to a voltage divider ratio as a function of the duty cycle of the pulse width modulation to thereby generate a voltage signal; and (b) a voltage-to-current converter configured to generate a simulated GFI current as a function of the voltage signal generated by the modulator circuit. The device may further comprise a current-to-voltage converter configured to measure the simulated GFI current from the voltage-to-current converter, and configured to convert the measured simulated GFI current to a voltage representative of the simulated GFI current; and an analog-to-digital converter configured to convert the representative voltage to a digital microprocessor feedback signal. 
     A test unit embodiment for evaluating an electric vehicle charging device may comprise an interface configured to receive a code associable with a data store; and a microprocessor having access to the data store; wherein the microprocessor is configured to: (a) receive a first code and associate the first code with the electric vehicle charging device; (b) receive a second code and associate the second code with a work order; and (c) receive a third code and associate the third code with a person requesting to address the work order; and (d) permit use of the test unit with the electric vehicle charging device based on a confirmation of at least two of: (i) code of the electric vehicle charging device; (ii) code of a work order; and (iii) code of the requesting person. The interface, of the exemplary test unit embodiment configured to receive a code associable with a data store, may be a barcode reader input module, where the first code is a first read barcode, the second code is a second read barcode, and the third code is a third read barcode. 
     An embodiment may include a method for determining permission to evaluate an electric vehicle charging device by a test unit, the exemplary method comprising: (a) receiving a first code representing the electric vehicle charging device; (b) receiving a second code representing a work order; (c) receiving a third code representing a person requesting to address the work order; and (d) if at least two of the codes are associable to permit access to the electric vehicle charging device, granting, by the test unit, permission for the test unit to access the electric vehicle charging device. The first code of the exemplary method may be a first read barcode, the second code may be a second read barcode, and the third code may be a third read barcode. 
     Another exemplary test unit for evaluating an electric vehicle charging device, may comprise a configurable load simulator wherein a first load simulating a first electric vehicle load is available via a first microprocessor-controlled switch being closed and a second microprocessor-controlled switch being open, a second load simulating a second electric vehicle load is available via the first microprocessor-controlled switch being open and the second microprocessor-controlled switch being closed, and a third load simulating a third electric vehicle load is available via the first microprocessor-controlled switch being closed and the second microprocessor-controlled switch being closed. For some embodiments, the first load may be about 2.2 kilowatts, the second load may be about 4.4 kilowatts, and the third load may be about 6.6 kilowatts. 
     A test unit embodiment, for evaluating an electric vehicle charging device, may comprise: (a) a microprocessor and memory wherein the memory comprises instructions for the electric vehicle charging device; and (b) a circuit configured to convert the instructions from the microprocessor for transmission to the electric vehicle charging device via a pilot line. 
     Another test unit embodiment, for evaluating an electric vehicle charging device, may comprise: (a) analog to digital conversion circuitry configured to receive analog signals from the electric vehicle charging device and convert at least a portion of the received analog signals into digital signals; and (b) a microprocessor and data store wherein converted digital signals may be stored, the microprocessor configured to receive at least a portion of the digital signals and save them to the data store. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, and in which: 
         FIG. 1  is an exemplary embodiment of an electric vehicle supply equipment (EVSE) charging an electric vehicle (EV) (or plug-in hybrid electric vehicles (PHEV)); 
         FIG. 2  depicts a top-level system block diagram of an EVSE to EVSE service tool (EVSA) embodiment; 
         FIG. 3  depicts a top-level block diagram of EVSE installation with EVSA; 
         FIG. 4  is a top-level EVSA functional block diagram; 
         FIG. 5  is a functional block diagram of a portion of the EVSA; 
         FIG. 6  is an exemplary EVSA enclosure; 
         FIG. 7  is an exemplary depiction of an EVSA control panel; 
         FIG. 8  is an exemplary depiction of an EVSA control panel; 
         FIG. 9  is an exemplary system block diagram of the electrical system of an EVSA; 
         FIG. 10  is an exemplary functional block diagram for a printed circuit board assembly of an EVSA; 
         FIG. 11  is an exemplary functional block diagram for a printed circuit board assembly of an EVSA; 
         FIG. 12  is an exemplary functional block diagram for a printed circuit board assembly of an EVSA; 
         FIG. 13  is an exemplary flowchart for a method of permitting use of the EVSA that may be executed by the EVSA; 
         FIG. 14  is an exemplary functional block diagram depicting communication between the EVSA and the EVSE via the pilot line; 
         FIGS. 15A-15B  illustrate an exemplary schematic depicting the simulation of the pilot line of an EV by the EVSA; 
         FIG. 16  is an exemplary functional block diagram depicting the simulation by the EVSA of a ground fault for testing the Ground Fault Interruption (GFI) circuit of the EVSE; 
         FIG. 17  is an exemplary schematic depicting the simulation by the EVSA of a ground fault for testing the GFI circuit of the EVSE; and 
         FIG. 18  is a functional block diagram depicting the load switching circuitry of the EVSA. 
     
    
    
     DETAILED DESCRIPTION 
     Electric Vehicles (EVs) and Plug-In Hybrid Electric Vehicles (PHEVs) are being offered in the market and require an AC electric supply in order to charge the vehicle batteries. The device that supplies the AC electricity to the electric vehicle is known as Electric Vehicle Supply Equipment (EVSE). If an electric vehicle is not present there is generally no way to test the function of the EVSE. Embodiments, may include an automated circuit to simulate the actions of a J1772 based charger pilot signal. An automated circuit to simulate the actions of a SAE-J1772 based charger pilot signal and the supporting Electric Vehicle Supply Equipment (EVSE) functions, particularly an EVSE service tool for verifying the installation, debugging and troubleshooting the operational issues in the field. Some embodiments may operate as an EVSE service tool for verifying the installations and debugging and troubleshooting the operation issues in the field. Embodiments enable the EVSE to be tested and serviced with or without an EV or PHEV connected, and thereby reduce potential damage to the EV or PHEV that may be caused by a faulty EVSE. 
       FIG. 1  is an exemplary embodiment of an electric vehicle supply equipment (EVSE) charging an electric vehicles (EV), or plug-in hybrid electric vehicles (PHEV). An EVSE  110  is depicted as connected via a breaker  120  to a utility power source  130 . The EVSE  110  is depicted as having a microcontroller  111 , a status panel  113 , and means of interfacing  112  such as wireless, Ethernet, and other means as a universal serial bus (USB). The EVSE  110  is depicted as connectable to an electric vehicle  140  having a receiving port  141  via a cable  150  having a connector  151  such as a J1772 (type II) connector  151 . 
     An EVSE service tool (EVSA) may be used to simulate an EV and thereby support the testing of the functionality of the EVSE.  FIG. 2  depicts a top-level system block diagram of an EVSE  110  to EVSA embodiment where the EVSE service tool (EVSA)  210  has a port  211  for receiving the charge plug  151 , and having a user interface depicted as a panel  220  for display and control input.  FIG. 3  depicts a top-level block diagram of an EVSE  110  installation with EVSE Service Tool (EVSA)  210  where power line  1  (L 1 )  321 , power line  2  (L 2 )  322 , a pilot line  323 , and a ground line  324  are depicted as engaging the service tool  210 . The power line  1  (L 1 )  321  and power line  2  (L 2 )  322  are depicted as provided to AC power test circuits and GFI test circuits  331 . The pilot line  323  is depicted as provided to the automated pilot test and control circuitry  332 , and the ground line  324  is depicted as provided to the automated pilot test and control circuitry  332 , and to a proximity tester  333 . With an EVSE connected to AC power, the EVSE output J1772 connector may be attached to a J1772 receptacle on the device. Following a proper sequence as outlined in J1772, the EVSA will then typically drop the initial EVSE voltage of 12V to a voltage of 9V which indicates “connected” between the EVSE and the EVSE service tool, i.e., the simulated EV. The automatic sequencer of the EVSE service tool (EVSA) may then initiate a pilot voltage drop to 6V as a “charging” indication (or 3V for a ‘vent required” charge) to confirm that the EVSA is ready to accept energy. The EVSA may read the pulse width of the pilot signal from the EVSE in order to determine the maximal current draw from the EVSE, and display the reading to the servicing person. The EVSE may then close the contactor, and provide AC voltage to the EVSA. The EVSA may comprise load steps that the service personnel can apply in steps. The EVSA may dissipate energy through the load device verifying that the EVSE is capable of providing current to an EV. The EVSA may also generate a Ground Fault Interruption (GFI) current to test the ground fault circuit in the EVSE. The voltage monitor circuit in the EVSA may provide over/under voltage indication, for example. The voltage monitor may also determine the system impedance of the EVSE in conjunction with the load capability. Various controls in the EVSA may also allow the servicing person to test other functions such as, but not limited to, “loss of pilot,” “loss of ground,” and “incorrect pilot voltage level.” Standard fused meter connectors may be provided to allow the servicing person safe access to the system voltages and signals for monitoring purposes. 
       FIG. 4  is a top-level EVSE service tool (EVSA) functional block diagram depicting a microcontroller  410  of the service tool  210  in communication with AC power controls  411 , signal monitoring circuitry  412 , AC augmented battery power supply circuitry  413 , communication circuitry  414 , AC load circuitry  415 , a user interface  220 , a proximity tester  333 , and GFI testing circuitry  416 . 
       FIG. 5  is a functional block diagram of a portion of the EVSE service tool (EVSA)  210 , or test unit, where the service tool is depicted as having a microprocessor  410  running an operating system  520  that supports an application  521  executing steps of data gathering, data associating, and preparing associated data for transmission. The microprocessor  410  is depicted as in communication via a data bus  540  with a memory store  530  where the microprocessor  410  may store the data. The microprocessor  410  is also depicted as being in communication with a user interface  220 , a device interface  551  that may engage an optional multimeter  560  or multimeter circuitry or digital input such as the output of a barcode scanner or barcode input module. The microprocessor  410  is also depicted as being in communication with another device interface  552  that may be a USB port configured to engage an optional flash drive  570  having a USB interface. The microprocessor  410  is also depicted as being in communication with a pilot line interface  553  that may receive input from the pilot line  323  of the EV charging unit  110 . The microprocessor  410  is also depicted as being in communication with power line L 1   321  and power line L 2   322  of the EV charging unit  110  via a power source interface  554 . 
       FIG. 6  is an exemplary EVSE service tool (EVSA) enclosure  610  where a control circuitry layer  611  may be separate from a layer of banks of resistors  612 . A first heat sink layer  613  is depicted as abutting the layer of banks of resistors  612 , and comprising airflow ducting  614 . A second heat sink layer  615  is depicted as abutting the first heat sink layer  613 . 
     The user interface  220  ( FIG. 2 ) for the EVSE service tool  210  may be in various arrangements. An exemplary EVSE service tool (EVSA) control panel is depicted in  FIG. 7 .  FIG. 7  depicts the exemplary control panel as having a line voltage readout  710 , an array of status light  720 , an array of binary switches  730 , and an array of system voltage check lights  740 .  FIG. 8  is an exemplary depiction of another exemplary EVSE service tool (EVSA) control panel where there is a four line, 20 character display window  810 , an array of status lights  820 , a pair of discrete on/off buttons  830 , and a five-key interface  840  for interacting with the display  810   
       FIG. 9  is an exemplary system block diagram of the electrical system of an EVSA where the system control may be embodied via printed circuit board assembly (PCBA)  910 . The system block diagram depicts a J1772 connection  921  in communication with the PCBA  910 , in communication with a solid state load switch  922  which is in turn in communication with a resistive load bank  923 .  FIG. 9  depicts a thermal switch  924  in communication with the PCBA  910  and in communication with the solid state load switch  922 . The J1772 connection  921  may invoke a fan circuit  925 . The PCBA is depicted as connected to a battery  930 . The system control PCBA  910  may receive input from one or more test clips  941 , a bar code wand  942  or external memory  943  via a USB, EVSE digital communication, e.g., via RS 232, RS-485, and via the pilot line  944 , one or more control panel keys  945 , and optionally a control panel touch screen  946 . The system control PCBA  910  may provide signals and/or data to the bar code wand  942  or external memory  943  via a USB, and/or digital communication RS 232/RS-485 to the EVSE via the pilot line  944 , one or more control panel LCDs  945 , and control panel characters of an LCD and/or LED display  946 . 
       FIG. 10  is an exemplary functional block diagram for a printed circuit board assembly of an EVSA where the system microcontroller  1010  is in communication with a revenue grade meter  1020 . The test clip signals  1030  are depicting as originating from four main contactor terminals and ground. The J1772 connector signals  1040  are depicted as comprising the AC Line 1 voltage, the AC line 2 voltage, the AC current, the ground, the pilot, and the proximity readings. The pilot signal conditioning  1050  is depicted as including signal condition for one or more amplitude measurements, for one or more frequency measurements, and for one or more duty cycle measurements. The pilot signal loading  1060  is depicted as setting a valid load for all expected J1772 conditions, and to test for non-valid loading. The proximity signal measurement circuitry  1070  is depicted as measuring the latch button press resistance and the connection resistance. The AC power detection circuitry  1080  is depicted as checking for AC power independent of the microcontroller, and may be configured to operate the LED directly. 
       FIG. 11  is an exemplary functional block diagram for a printed circuit board assembly of an EVSA where the system microcontroller  1010  is depicted as receiving ambient temperature measurements  1110 , real time clock input  1120 , and a precision voltage reference  1130 . The system microcontroller  1010  is depicted as providing command signals to a load switch drive  1140  that in turn provides drive signal for various switch types, e.g., three switch types. The system microcontroller  1010  is depicted as providing data for the display interface  1150 , and providing a beeper signal for an audible alarm  1160 . The system microcontroller  1010  is depicted as exchanging data with: (a) the control panel interface  1171  to interface with a membrane key switch ( FIG. 8 ) and LED drivers; (b) flash memory or micro SD memory  1172  to record operational activity and to store program instructions update code; (c) a USB interface  1173  to enable a USB connection for a bar code reader and/or a USB connection for a memory device; (d) the EVSE via EVSE data communication  1174 , i.e., via RS-232, RS-485, and the pilot signal; and (e) debug and program interfaces  1175 , e.g., RS-232, JTAG, and/or USB boot loader. 
       FIG. 12  is an exemplary functional block diagram for a printed circuit board assembly of an EVSA where the system microcontroller  1010  interfaces with a battery management system  1210  by providing an auto shut off command and/or a low battery shut off command. The battery management system  1210  is depicted as receiving from the control panel  230  the affect of manually effected on and off switches. The control panel OFF switch may function to request that the microcontroller  1010  save to memory and then shut off. The control panel OFF switch may override the auto off switch of the microcontroller  1010 , if after a time delay the microcontroller does not responds with a memory save and then shut off. The battery management system  1210  is depicted as receiving power from an off-board battery  1220 , e.g., six 1.5V cells. The battery management system  1210  is depicted as being configured to provide main 5V dc-dc power supply  1230 , main 3.3 V dc-dc power supply  1240 , and isolated plus or minus 5V supply  1250 . 
       FIG. 13  is an exemplary flowchart  1300  for a method of permitting use of the EVSA, a method that may be executed by the EVSA where a test unit for evaluating an electric vehicle charging device, i.e., an EVSE, comprises a barcode reader input, and the microprocessor is configured by loading instructions from a memory store to: (a) receive a code, e.g., a read barcode of the electric vehicle charging device  1310 ; (b) receive a code, e.g., a read barcode of a work order  1320 ; and (c) receive a code, e.g., a read barcode of a badge of a person requesting to address the work order  1330 . The configured microprocessor may grant permission  1340  for use of the test unit, i.e., the EVSE service tool (EVSA) with the electric vehicle charging device (EVSE) based on a confirmation of at least two of: (i) the code of the electric vehicle charging device; (ii) the code of a work order; and (iii) the code of the badge of the requesting person. 
     A charger cable may comprise AC Line 1, AC Line 2, a ground line, and a pilot line. Of the lines, the pilot line may provide for two-way communication.  FIG. 14  is an exemplary functional block diagram depicting communication between the EVSA  210  and the EVSE  110  via the pilot line  323  of a charger cable  150 . The pilot line  323  may be used to upload revised instructions for storage and execution by the microcontroller  111  of EVSE  110  where the EVSE may store such instructions in reprogrammable nonvolatile memory, e.g. flash memory. The EVSE service tool (EVSA) may also simulate the pilot signal circuitry of an electric vehicle.  FIGS. 15A-15B  illustrate an exemplary schematic depicting the simulation of the pilot line of an EV by the EVSA. 
       FIG. 16  is an exemplary functional block diagram depicting the simulation by the EVSA of a ground fault for testing the GFI circuit of the EVSE. That is,  FIG. 16  is an exemplary functional block diagram of a pulsed DC circuit  1600  that produces a GFI current for test of the AC line  1601 . The AC line  1601  is directed to a full-wave bridge rectifier  1610 . The output of the full-wave bridge rectifier  1610  is an input signal  1611  that is directed to a modulating subsystem  1620  that produces an amplitude-adjusted version of the input voltage signal  1611  via pulse width modulation (PWM). An exemplary modulating subsystem  1620  is depicted as comprising a microprocessor  1621  external to the bridge, that may be in communication with a modulator inside the bridge via a digital signal isolator (not shown), a series of resistors  1622 , and a high frequency switch, or modulator, such as an N-channel MOSFET  1623 , for generating a PWM based on the PWM signal received from the microprocessor. The output, i.e., the modulated input voltage signal  1624 , is directed to a voltage-to-current converter subsystem  1630  that is depicted as comprising: (a) an analog filter  1631 , to reduce the PWM modulating chopping effect on the modulated input voltage signal  1624 ; (b) an NPN transistor  1632 ; and (c) a series of resistors  1633 , to reduce the stress on the transistor  1632 . The analog filter output  1634  has a voltage affected by the PWM duty cycle, and in turn affects the base voltage of the transistor  1632 . A current-to-voltage subsystem is depicted by  1660  where the resistor  1661  between the full-wave bridge rectifier X 10  and ground allows for an analog filter  1662  to measure the GFI current, and convert the measured GFI current into a voltage. The voltage signal may then be converted to a digital signal for use by a microprocessor for feedback control of the GFI current. 
       FIG. 17  is an exemplary schematic depicting the simulation by the EVSA of a ground fault for testing the GFI circuit of the EVSE, e.g., a GFI 20 mA test. That is,  FIG. 17  is an exemplary schematic embodiment of the preceding functional block diagram where a full-wave bridge rectifier  1710  provides rectified AC as the input voltage signal to a power supply  1720 . A voltage divider  1750  may produce an output signal proportional to the input voltage signal. A digital signal isolator  1730  is depicted as taking in a GFI PWM modulation signal  1731  at pin  2 , and outputs as pin  6  a GFI PWM signal  1732 . A voltage divider  1750  may produce an output signal proportional to the input voltage signal. A modulator  1760  is depicted as an N-channel MOSFET that may provide linear adjustments to the voltage divider ratio as a function of the duty cycle of the GFI PWM signal  1732 . A low pass filter  1782  attenuates the chopping signal of the modulator  1760 . A voltage-to-current converter  1780  may produce the GFI current  1781  as a function of the input voltage signal from the modulator  1760 . A current-to-voltage converter  1740  is depicted as configured to measure the GFI current and convert  1741  the measurement to a voltage. The voltage signal may then be converted  1770 , via an analog-to-digital convert (ADC)  1770  to a digital signal  1771  for use by a microcontroller (not shown) for feedback control of the GFI current X 81 . 
       FIG. 18  is a functional block diagram depicting the load switching circuitry of the EVSA. That is,  FIG. 18  depicts a switchable load embodiment  1800  of a test unit where a microcontroller  1810  controls a plurality of switches, e.g., a first switch  1821 , SW_ 1 , and a second switch  1822 , SW_ 2 . A first resistor bank  1830  comprises two resistors, each sized to draw five amps at 240 volts, e.g., 48 ohms. A second resistor bank  1840  comprises four resistors, each sized to draw five amperes of current at 240 volts, i.e., 48 ohms. The microcontroller  1810  may close the first switch  1821 , SW_ 1 , where the input voltage is 240V. Accordingly, the first resistor bank  1830  may draw 10 amps and provide a load of 2.4 kVA, about 2.4 kilowatts for a power factor less than unity. The microcontroller  1810  may leave open the first switch  1821 , SW_ 1 , and close the second switch  1822 , SW_ 2 . The second resistor bank  1840  may draw  20  amperes and provide a load of 4.8 kVA, i.e., about 4.8 kW. The microcontroller  1810  may close both the first switch  1821 , SW_ 1  and the second switch  1822 , SW_ 2 . The combined first resistor bank  1830  and second resistor bank  1840  may draw 30 amperes and provide a load of 7.2 kVA, i.e., about 7.2 kW. Accordingly, embodiments of a test unit may simulate the load of one of three electric vehicle levels while using two resistor banks That is, by microcontroller effected switches, banks of resistors may be used in combination to reduce the number of total resistors required for a desired range of loads, e.g., 2.2 kW, 4.4, kW, and 6.6 kW for available EVs. 
     It is contemplated that various combinations and/or sub-combinations of the specific features and aspects of the above embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments may be combined with or substituted for one another in order to form varying modes of the disclosed invention. Further it is intended that the scope of the present invention herein disclosed by way of examples should not be limited by the particular disclosed embodiments described above.