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Assembled PCB |
PCB with DIN Rail enclosure |
Finished EVSE |
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Contents
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1. Overview 2. Why Another EVSE? 3. Circuit States & LEDs 4. Charge Current Selection 5. Circuit Description |
6. Emergency Shutdown 7. Access Control 8. Limitations 9. Hints & Modding 10. Construction Manual |
11. Testing 12. Downloads 13. Ordering 14. Disclaimer |
External LED green Connected |
External LED blue Charging |
External LED red Error |
Onboard LED yellow Connected |
Onboard LED green Charging |
Onboard LED red Error |
Pilot signal |
Relay |
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No EV connected | off |
off |
off |
off | off |
on | +12V |
off |
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EV connected | on |
on |
off |
1 kHz square wave |
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EV charging | off |
on |
on |
on |
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EV requesting ventilation | |||||||||
Pilot short circuit | off |
on |
off |
on |
1 kHz square wave3 |
off |
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Diode failure | on1 |
off 2 |
1 with EV
connected
2
without EV connected
3
J1772 requires -12V DC vor. See chapter Limitations.
Note: Using an
RGB LED with a common anode is possible since all LEDs have one
pin at Vcc and only one LED lights up at a time.
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The
power supply is a simple +/-12V stabilized circuit using
7812/7912. The current requirements are so low that a simple
half-wave rectifier is sufficient. The positive branch is
elevated by 0.8V using a diode in order to compensate for the
voltage loss of the pilot signal generation circuit.
Note:
the negative supply voltage requires a few milliamps load in
order to remain stable. Therefore, the onboard power LED is
mandatory.
The
square wave signal is generated by one comparator producing a
triangle wave and a second comparator transforming it into the
square wave. The second comparator's reference voltage defines
the duty cycle and can be adjusted using an external resistor.
Using no external resistor sets the charge current to 8A.
The square wave signal is split into its negative and positive half-waves. Both are rectified and filtered to a stable DC (peak) voltage. The negative part must remain below -11V at all times (diode check) or the circuit will go to error state.
If the
positive part is below 10V the EV connected LED will light up.
If it is between 7V and 7V the relay will switch on and the
charging LED will light up. For all positive voltages below 2V
(short circuit) the circuit will go to error state. The various
reference voltages are generated by a string of resistors
forming a multi-voltage divider.
The
pilot signal is generated by two comparators and boosted by a
transistor. It is at +12V DC when no EV is connected.
The relay driver has a
4.7μ capacitor for slightly delaying the relay. In case of a
pilot short circuit the rectified peak voltage falls slowly and
crosses the charging voltage window for a very short period of
time. This would trigger a tiny undesired relay click. The
capacitor delays the relay signal for a moment and suppresses
the spike.
The LED driver circuit
has some extra transistors for suppressing undesired LED
signals. The "Error" LED and the "EV Charging" LED switch off
the "EV Connected" LED so that only one LED at a time is on.
An emergency shutdown
is not part of the circuit. However, it can be implemented
easily with a switch that interrupts the 230V power supply. This
will remove power from the circuit and the relay will open.
Please note that an emergency shutdown should only be used in
cases of emergency because the EV prefers to shut down the
charging process gracefully.
The following components are required for building the controller:
Value |
Components |
Count |
5.6nF (NP0,
low temperature drift) |
C1 |
1 |
100nF |
C2,C5,C6,C8 |
4 |
1uF |
C10 |
1 |
220nF |
C7 |
1 |
4.7uF/16V |
C9 |
1 |
220uF/16V |
C11 |
1 |
330uF/35V |
C3,C4 |
2 |
1k |
R10,R18 |
2 |
1k/1W |
R9 |
1 |
1k5 |
R3 |
1 |
2k2 |
R22 |
1 |
3k3 |
R15 |
1 |
4k7 |
R14,R23,R24,R25,R28,R29,R30 |
7 |
5k6 |
R1,R16 |
2 |
10k |
R2,R6,R7,R8,R11,R21 |
6 |
15k |
R17 |
1 |
47k |
R19,R27 |
2 |
100k |
R4,R5,R20,R26 |
4 |
1M |
R12,R13 |
2 |
Trim pot 100k |
RV1 |
1 |
Trim pot 10k |
RV2 (optional) |
1 |
Fuse 100mA
- 160mA |
F1 |
1 |
Fuse carrier |
F1 |
1 |
Relay |
K1 |
1 |
Terminal 2 Pin |
P1,P2,P3,P4,P6 |
5 |
Terminal 3 Pin |
P5,P7 |
2 |
Transformer 12V |
T1 |
1 |
DIP 14
carrier |
U1,U4 |
2 |
1n4002 |
D1,D2 |
2 |
1n4148 |
D3,D4,D5,D6,D7 |
5 |
SD101C |
D9 |
1 |
BC337-40 |
Q1,Q2,Q4 |
3 |
BC557 |
Q3 |
1 |
LM2901 |
U1,U4 |
2 |
LM7812 |
U2 |
1 |
LM7912 |
U3 |
1 |
LED 3mm yellow |
D10,D11 |
2 |
LED 3mm red |
D12 |
1 |
LED 3mm green |
D8 |
1 |
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If
none of these measuring equipment is available the
calibration can also be performed acoustically. Connect a
diode and a speaker to the Pilot signal terminals as show
in the diagram. When the controller is switched on you
will hear a beeping sound from the speaker. You can either compare the pitch of the sound to an instrument (it must lie between h'' and c''') or you can measure it with a tuner, using your phone, with a spectral analyzer or oscilloscope app. If the frequency is not adjusted properly the car will not respond to the controller reliably or not at all. |
Once the PCB is
completed the interesting quesion arises: will it work? In order
to test the functionality of the assembly you need an EV
simulator and an oscilloscope for troubleshooting.
The EV simulator is a
simple circuit which mimics the correct behaviour of the EV and
can simulate two distinct errors. The simulator is available as
a kit from OpenEVSE but it is so simple that it can be
built point to point.
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SW1 |
EV connected |
SW2 |
EV charging (with SW1 closed) |
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SW3 |
CP short circuit |
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SW4 |
Diode failure |
With the pilot signal from the AnalogEVSE PCB connected to the
EV simulator you can test the following conditions using the
onboard LEDs:
SW1 |
SW2 |
SW3 |
SW4 |
Zustand |
LED Conn |
LED Charge |
LED Error |
Relais |
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off |
off |
off | off | Idle
/ no EV |
off |
off |
on |
off |
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on |
EV
connected |
on |
off |
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on | Charging |
on |
on | ||||||
don't care |
on | Pilot
signal short circuit |
off |
on |
off |
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SW1 and/or SW2 |
on | Diode error |
AnalogEVSE was designed using KiCad 4.0.2. KiCad is a free
EDA software package available for Windows, Linux and Mac OS X.
The KiCad project is hosted on Github. Please remember that the
latest revisions may not work.
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Github: | https://github.com/helmutheinz2002/analogevse Files of the KiCad project |
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Zip-Archive: |
analogevse-1v8r2-2017-04-19.zip Archive of version 1v8r2 which matches this documentation and was used for manufacturing the current batch of PCBs analogevse-1v8-2016-09-20.zip Archive of version 1v8 which matches this documentation and was used for manufacturing the first batch PCBs |
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KiCad: |
Downloads KiCad Software Download |
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Wiring Diagram: |
AnalogEVSE-1v8-Wiring.pdf Wiring Diagram for a wallbox using the AnalogEVSE controller |
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You can order the PCB or a full kit from
me using the email address listed below. Postage is included for
shipping within Germany. For shipping to foreign countries
please inquire and I will investigate shipping costs.
Delivery time for a kit is approximately
one week since I may have to obtain some components before
shipping. PCBs can be shipped immediately as long as my stash
lasts.
Please note: if you order the PCB
only you will need to find a number of components that match the
footprint on the PCB (e.g. the transformer). Moreover, the PCB
size is tuned exactly to the DIN rail enclosure I use. The kit
includes all components that will match the PCB and the PCB will
fit nicely into the box.
(C) 2015 Bernhard
Walter
AnalogEVSE is open
source hardware. I designed it for my needs and although I
designed it carefully I cannot guarantee that it is free of
errors. Use it at your own risk.
You are free to build, copy and modify the circuit and its
documentation as long as you include the original copyright
notice and this disclaimer.
Use caution when
working with high voltage. It may kill you.
I am not responsible for the content of linked external web
pages.
Contact: analogevse@web.de
Changelog:
2015-11-19: Correction of minor error in PCB layout. Version
changed from 1.3 to 1.4.
2015-11-22: PCB redesign for a standard transformer
2016-09-10: Version 1.8
2016-09-20: C11 added
2016-11-04: correction of charge current table
2016-11-07: correction of C10 in BOM
2017-04-19: New PCB layout, new email address
2018-09-25: Minor corrections: C1 NP0, LED states for testing
2019-01-01: Kits and PCBs no longer available