U.S. patent application number 13/299144 was filed with the patent office on 2012-05-10 for electric vehicle simulator and analyzer (evsa) for electric vehicle supply equipment.
Invention is credited to Scott Garret Berman, Blake Edward Dickinson, Albert Joseph Flack, Keith Michael Kolb.
Application Number | 20120116745 13/299144 |
Document ID | / |
Family ID | 43733086 |
Filed Date | 2012-05-10 |
United States Patent
Application |
20120116745 |
Kind Code |
A1 |
Dickinson; Blake Edward ; et
al. |
May 10, 2012 |
Electric Vehicle Simulator and Analyzer (EVSA) for Electric Vehicle
Supply Equipment
Abstract
Embodiments pertain to 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.
Inventors: |
Dickinson; Blake Edward;
(Monrovia, CA) ; Flack; Albert Joseph; (Garden
Grove, CA) ; Kolb; Keith Michael; (West Covina,
CA) ; Berman; Scott Garret; (Los Angeles,
CA) |
Family ID: |
43733086 |
Appl. No.: |
13/299144 |
Filed: |
November 17, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13145785 |
Sep 23, 2011 |
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PCT/US2010/048179 |
Sep 8, 2010 |
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13299144 |
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61240577 |
Sep 8, 2009 |
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61246469 |
Sep 28, 2009 |
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Current U.S.
Class: |
703/18 ;
235/382 |
Current CPC
Class: |
B60L 53/66 20190201;
Y02T 10/72 20130101; Y02T 10/7088 20130101; G01R 31/40 20130101;
B60L 53/62 20190201; Y02T 10/70 20130101; Y02T 90/128 20130101;
Y02T 90/16 20130101; Y02T 10/725 20130101; Y02T 10/7005 20130101;
B60L 53/18 20190201; Y02T 10/7072 20130101; Y02T 90/121 20130101;
G01R 31/006 20130101; B60L 53/305 20190201; B60L 53/31 20190201;
B60L 2210/20 20130101; Y02T 90/127 20130101; Y02T 90/163 20130101;
Y02T 90/12 20130101; Y02T 90/14 20130101 |
Class at
Publication: |
703/18 ;
235/382 |
International
Class: |
G06G 7/63 20060101
G06G007/63; G06K 5/00 20060101 G06K005/00 |
Claims
1. An electric vehicle simulator and analyzer for electric vehicle
supply equipment, the electric vehicle simulator and analyzer
comprising: a control processing unit comprising a processor and
addressable memory; the control processing unit configured to:
display a result of at least one of: a ground fault interrupt
current simulation, and a pilot line feedback simulation.
2. The electric vehicle simulator and analyzer of claim 1 wherein
the control processing unit is further configured to display a
result of a electric vehicle load simulation.
3. The electric vehicle simulator and analyzer of claim 1 wherein
the result of the at least one simulation is configured to indicate
at least one of: maximal current draw from the electric vehicle
supply equipment, current provided by the electric vehicle supply
equipment, loss of pilot, loss of ground, operation of ground fault
interrupt circuit in the electric vehicle supply equipment, over
voltage level, under voltage level, and incorrect pilot voltage
level.
4. The electric vehicle simulator and analyzer of claim 1 wherein
the control processing unit is further configured to: display a
result of at least one of: a first alternating current (AC) power
line test, a second AC power line test, a pilot line test, a ground
line test, and a proximity test.
5. The electric vehicle simulator and analyzer of claim 4 wherein
the result of the at least one test is configured to indicate at
least one of: maximal current draw from the electric vehicle supply
equipment, current provided by the electric vehicle supply
equipment, loss of pilot, loss of ground, operation of ground fault
interrupt circuit in the electric vehicle supply equipment, over
voltage level, under voltage level, and incorrect pilot voltage
level.
6. The electric vehicle simulator and analyzer of claim 2 wherein
the control processing unit is further configured to simulate the
electric vehicle load via a drop in an initial voltage of about 12
volts to at least one of: 9 volts, 6 volts, and 3 volts.
7. An electric vehicle simulator and analyzer for electric vehicle
supply equipment comprising: a control processing unit comprising a
processor and addressable memory; the control processing unit
configured to: receive at least one of: a first barcode, a second
barcode, and a third barcode; confirm permission upon reception of
at least two of: the first barcode, the second barcode, and the
third barcode; and if permission is confirmed, allow operation of
the electric vehicle simulator and analyzer.
8. The electric vehicle simulator and analyzer of claim 7 wherein
the first barcode is associated with a electric vehicle supply
equipment, the second barcode is associated with a work order, and
the third barcode is associated with a person requesting to address
the work order.
9. The electric vehicle simulator and analyzer of claim 7 further
comprising an interface configured to receive a barcode associable
with a data store.
10. An electric vehicle simulator and analyzer for electric vehicle
supply equipment comprising: a control processing unit comprising a
processor and addressable memory; the control processing unit
configured to: control a first switch of a plurality of switches to
at least one of: a open position, and a closed position; control a
second switch of a plurality of switches to at least one of: an
open position, and a closed position; and simulate at least one of:
a first electric vehicle load, a second electric vehicle load, and
a third electric vehicle load; wherein the first electric vehicle
load is simulated via controlling the first switch to the closed
position and the second switch to the open position; the second
electric vehicle load is simulated via controlling the first switch
to the open position and the second switch to the closed position;
and the third electric vehicle load is simulated via controlling
the first switch to the closed position and the second switch to
the closed position.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application 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 which are
incorporated by reference herein for all purposes.
TECHNICAL FIELD
[0002] Embodiments pertain to simulator circuitry, particularly to
simulator circuitry configured to simulate an electric vehicle and
test an electric vehicle charger.
BACKGROUND
[0003] Methods and apparatuses for simulating an automated battery
tester with a fixed resistance load have been proposed.
SUMMARY
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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
[0011] Embodiments are illustrated by way of example and not
limitation in the figures of the accompanying drawings, and in
which:
[0012] FIG. 1 is an exemplary embodiment of an EVSE charging an EV
(or PHEV) FIG. 2 depicts, a top-level system block diagram of an
EVSE to EVSA embodiment;
[0013] FIG. 3 depicts a top-level block diagram of EVSE
installation with EVSA;
[0014] FIG. 4 is a top-level EVSA functional block diagram;
[0015] FIG. 5 is a functional block diagram of a portion of the
EVSA;
[0016] FIG. 6 is an exemplary EVSA enclosure;
[0017] FIG. 7 is an exemplary depiction of an EVSA control
panel;
[0018] FIG. 8 is an exemplary depiction of an EVSA control
panel;
[0019] FIG. 9 is an exemplary system block diagram of the
electrical system of an EVSA;
[0020] FIG. 10 is an exemplary functional block diagram for a
printed circuit board assembly of an EVSA;
[0021] FIG. 11 is an exemplary functional block diagram for a
printed circuit board assembly of an EVSA;
[0022] FIG. 12 is an exemplary functional block diagram for a
printed circuit board assembly of an EVSA;
[0023] FIG. 13 is an exemplary flowchart for a method of permitting
use of the EVSA that may be executed by the EVSA;
[0024] FIG. 14 is an exemplary functional block diagram depicting
communication between the EVSA and the EVSE via the pilot line;
[0025] FIG. 15 is an exemplary schematic depicting the simulation
of the pilot line of an EV by the EVSA;
[0026] 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;
[0027] 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
[0028] FIG. 18 is a functional block diagram depicting the load
switching circuitry of the EVSA.
DETAILED DESCRIPTION
[0029] 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.
[0030] 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.
[0031] 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 (L1) 321, power
line 2 (L2) 322, a pilot line 323, and a ground line 324 are
depicted as engaging the service tool 210. The power line 1 (L1)
321 and power line 2 (L2) 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.
[0032] 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.
[0033] 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 L1 321 and power line L2 322
of the EV charging unit 110 via a power source interface 554.
[0034] 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.
[0035] 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
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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
[0040] 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.
[0041] 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. FIG. 15 is an
exemplary schematic depicting the simulation of the pilot line of
an EV by the EVSA.
[0042] 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 X10
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.
[0043] 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 X81.
[0044] 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.
[0045] 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.
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