Open Source 6Kw Charger. Who Whats What Features?
 

Hello Everyone,

Clyde (williamson) came to me a few weeks ago with plans he has put together for a 6kW Charger. He has many years of experience designing high output power supplies. This charger is PFC corrected and Isolated. It can take 85-265VAC input at 50 or 60Hz. With the output being isolated, You cannot easily be shocked if you are working on the car while charging. The charger automatically detects what voltage it is powered with and adjusts it max draw as to try and not trip the circuit breaker. 15A for 115VAC and 30A for 230VAC. There will also be an adjustment knob on the front of the charger for turning the max current draw on that voltage down, if other loads are on the same circuit.

The limits of the charger right now is that it can only charge the battery voltage that is was wired for. While this can be changed, It requires removing or adding winds to the transformer to decrease or increase the voltage output. A small resistor mod is also required at the same time.

I am hoping to put together kits for people to build their own chargers specific to the voltages they want. This will be a modular design that you will be able to get different modules that will plug in to change the output stage to the voltage needed to charge the pack you want.

The charger should cost somewhere in the range of a few hundred dollars and each new output module will most likely be around one hundred each. I am not certain of these prices yet, as It is still in prototype phase.

So I need to know what you guys are looking for in a charger. Wether it be Higher Power, Wide Output, Narrow Output, Isolated, Non Isolated, Also what Kind of controls.

With the module setup, The controller could be programmed to remember a profile for each one, With different setpoints and charge currents.

Also, For reference, The Manzanita PFC 30 charger is alot like this one. It is not isolated and has an output range of 12-450VDC.

I want to know what you guys think!!

-Adam

I'm not shopping these days, but if I was, I'd be mostly concerned that the charger was smart about prolonging battery life. Perhaps a "fast charge to X%" control would be a great feature, too. In a portable charger, I'd want at least two cords, so I could take advantage of split duplex outlets. Even better would be cords set up to accept any combination.

I want a charger with wide voltage range , a simple digital display and controls and lots of amps! Not worried about isolation.

Spec's similar to a $2,700.00 Manzanita PFC 30 would be nice !!!! :thumbup:

For a charger an analog or digital (I could care less) display of volts/amps is nice. I like haveing a fairly wide range of voltages and a trim for finish.

Meaning something like my schumacher multivolt except I would like a simple cutoff so it doesn't severely overcharge. Even better would be 2 stage like my old K&W BC-20 where I can set the amps and the finishing charge voltage trim.
(I loved my K&W BC-20)

Output current isn't extremely important (but control of it might be since I opportunity charge and 10amp outlets need to be ramped down), but overcharge protection is (since I can't design that well myself)

In other words, the thing should shut down once the batteries are fully charged unless equalize or some other setting is chosen.

Cheers
Ryan

Something for us cheapskates to try to revive old batteries of various chemistries and sizes with would be cool, with a built in smart charger :)

I don't think there's any point in isolation since it is expensive, inefficient, and does not really provide much of a safety advantage since the output is still high voltage. If anything, isolation may make for a false impression of safety in a high voltage circuit. (I know of an electrical engineer who got zapped by an isolated 300v power supply because one side was grounded by the scope probe. She lived to tell the story, but it shows that isolated high voltage power supplies are not safe!)

PFC is normally unnecessary for home use, but it is easy to integrate it into a charger design. Just have rectified AC supply a buck/boost converter (buck followed by boost, with a shared inductor), with a few small, high ripple current capacitors to ensure a low source impedance. It will support a very wide range of output voltages. up to 450v or so is reasonable depending on the rating of the components. Regulation compliance can go all the way to 0v.

There will definitely have to be some analog control circuits. A good and simple way to control a buck/boost converter is to use double hysteresis current mode control. Basically, the buck part has a slightly higher setpoint than the boost part, such that the hysteresis ranges do not overlap. The setpoints are determined by more control circuits. There will be a comparator to set a "dead band" during which the converter stops operating, since efficiency is poor during low instantaneous input voltage. A clamp circuit can limit maximum input current as desired by limiting maximum control voltage. Another circuit will limit maximum output voltage.

The charge control can be either analog or digital. For lead acid, simply adding a timer to reduce the output voltage a time after the setpoint voltage is reached is enough. For Lithium or other chemistries, a microcontroller can be used to provide primary charge control. It can also use a control signal from the BMS.

One of my current projects is a high efficiency inverter-based power supply/float charger for a home network. It operates at much lower voltages and power levels, but the basic concept is the same.

How about a 48v lead acid charger that can run off a small generator without stalling it? I have a Reva G-Wiz :turtle:and a 1 kva generator but the on-board charger draws nearly 3kw in the early charge phase, so I can't use it for topups. A 3kva generator is too big and awkward for the car. A charger as above would be very handy
Huw

I'm looking for something that has the automatic input voltage adjustment, automatic shut down and I can move between lead acid and lithium easily. Also, a cost less than $400 would be nice.

I have a K&W BC-20 right now and it's a great charger, I just wish it shut down when done. And provided more power, I have access to 120 volt and 220 volt plugs but don't have a charger capable of handling 220v. Yet.:D

The open source charger of Simon Rafferty and myself fits that bill. Mine has been working for over a year now and just recently switched to lithium. Holds within 0.2v on cv phase.

WOW, I totally forgot about this thread.

I actually ordered the first prototype control board for the charger monday night. It should be here in a few weeks.

Some of the preliminary features will be:
Modular design: The control board uses a remote current sense and voltage sense board that allows for high resolution measurement using an energy metering IC. You can daisy chain up to 3 of these boards to the main controller to measure all the sources inside the controller. These would be AC input voltage and current, Power Factor Corrected DC voltage and current, and the only board that is required is DC output to batteries voltage and current. These boards can measure up to 400VDc or 264VAC RMS

Modular Driver: The driver outout section is designed to be customized to your needs. You can use a board that will output an analog referance voltage, you can use a MOSFET driver or you can use the HIGH popwer VLA500-01 IGBT driver, which can also drive mosfets.

Graphic Interface The main display of the unit is a decent size graphic LCD panel. It is backlit for easy viewing. This is where you can select what you want to use for charge profile.

Simple Interface: There is only 1 user interface to the charger. This is a rotary knob next to the LCD that you twist to move the selected item on the screen. You then push to select or set that item.

BMS Input: There is an input where you can connect a simple BMS signal that can be either 5 or 12 volts. (Jumper Selectable) This can be used for stop charging when a high cell condition occures, or could transfer the charger into the next stage of charge (Top Off)

Vehicle Interlock: There is an NO/NC relay included that will brovide charger interlock feature. You will be able to wire ignation or contactor coil through this relay to disable the vehicle as soon as power is applied to the charger. Once its removed, the vehicle will function properly.

Charger Contactor Control: This will be used to disconnect the battery pack from the charger when the charger is not charging. This is a 12-15V, depending on what the board is powered from.

Ethernet Connectivity: The control board includes a 10TBase ethernet connection for connecting the charger to a home network. With this you will be able to monitor the charger from the comforts of your house. This will also provide high speed networking communication to a BMS and other items.

Software Features:

The charger is designed for convinence. You will be able to program battery pack memory's for charging different vehicles with the same charger. So if you have a lawn mower with 48V Lead batteries you can set up a memory for that, then you can set another memory for you motorcycle and another for your car! All memories can be different chemistries also.

After that you can program different locations. Since the charger cannot detect the size of the circuit you have it plugged into, you have locations to limit current to pre determined levels. So you can have a home setting where you have a 30A 240V outlet in your garage, and the charger will limit input current (more accurately with AC sense board) to 30A. When you get to towk, you might have only a 15A 110V outlet that you can only effectively get 10A. Well you select the work location and the charger will limit current to 10A. You will be able to store up to 10 different locations as well.

Well thats all I can think of for now. I will add some more details as I remember them. ;)

-Adam

That's a lot of features. Does your charger need any field testing? :D

Adam forgot to mention that this charger is also self aware :)

The feature I would really like is a probe for hi-temp cutoff. I don't even use lithiums, but that's a big safety point for me. Also, more data for the ethernet connection (check whether you need to warm up the batteries in the winter before going outside)

The BMS input, as noted by Adam, would satisfy this requirement.
Then you could have temp reading or voltage reading or whatever else the BMS supplies as info into the charger.

Eric

Personally i'm not fussed about the UI. A multicoloured LED that goes green and blinky when the bike is charged will do me. Mostly because a bike has very little real estate for fancy screens and the like. Though perhaps if it sent a message (through wifi) when the charged was finished that would be neato.

My requirements are probably going to be different to most other people's because of the space restrictions a bike has. But i will eventually be going to north america so it'd have to accept 110v as well as 240v.

So for me it'd have to be flexible on the input power, simple to operate once set up, and physically small to fit on the bike. :P

Hi Adam,

It's been about a month since you ordered your Charger PCB, how's that project going ?

-Mark

Alright, Here is an update on the charger.

The boards that I ordered came in a few weeks ago. I had ordered the main control board, 2 different driver boards and a AC/DC digital isolated sense board. Heres a pic.
http://farm6.static.flickr.com/5132/...c4bd459f_z.jpg
Untitled by AdamBrunette, on Flickr

The main control board has a graphic LCD panel that is 128x64 pixels. The user interface is super simple design. A rotary knob with push to select. You will just turn the knob to scroll to the option you want or increase or decrease values and then push the knob to select or set a value. Its very user friendly. The board is powered from a wide range of voltages. A switching power supply has been included to regulate from 9 to 24V down to 5V for logic. The input to the main board is traced over to the modular driver section. The driver requires an isolated dc-dc if isolation is required. The isolated dc-dc converter was not included on the main board because power requirements is dependent on the driver used. To have a universal dc-dc onboard would only increase costs. Also included on the main board is a 10-TBASE ethernet connection for remote monitoring and control of the charger. A real time clock (RTC) which will allow the charger to keep track of what day and time it is. This way you can set up charge schedules to limit the charging power or charge at all to times where power isnt so expensive or whatever reason you want. I also included the features I listed before. BMS input od 5V or 12V, Vehicle interlock relay featuring NO and NC terminals. Also a MOSFET circuit to control a contactor on the DC bus common to the dc supply to the main board.

The driver boards are modular in this design. I thought this could be good for people that want flexibility in power and price. You will be able to choose a high power driver, which uses the VLA-502-01 Powerex driver module. This is a 12A high frequency (30-70khz) driver module with built in dc-dc converter and Vsat detection. This is mainly for IGBT's.

The other driver board I designed and ordered is one just for prototyping. I will use this one to break out the signals for PWM, +5v, +VIN, GND, and an adc pin that can be used for feedback. I will use this board to design a driver based on what the cougar uses. It will be good for simple and smaller MOSFET based power sections.

The last board I ordered is the AC/DC sense board. My plan for this board was to use an energy metering IC for accurate measurement of current and voltage. Current is measured using a 0.001R shunt resistor while voltage is measured with a voltage divider and filter circuit. The board has an on board AVR to talk to the metering IC over SPI. It then converts this data and sends it over serial to the main board over an isolated connection. It is a very accurate method for measuring these sources, but it is not as fast as hall sensors. Due to the cost of this one and its speed, I will not be using this board as planed to monitor DC output from the charger. It will be an optional input for monitoring AC power only. The chip is more suited to this anyways. it can measure Power Factor, apparent power, reactive power active power and much much more.

Alright time for some pics.
http://farm6.static.flickr.com/5137/...bc961368_z.jpg
Untitled by AdamBrunette, on Flickr

http://farm6.static.flickr.com/5053/...7f85438c_z.jpg
Untitled by AdamBrunette, on Flickr

Here is the back of the main board with the unpopulated vla-502-01 driver board.

http://farm6.static.flickr.com/5012/...ba8b2f20_z.jpg
Untitled by AdamBrunette, on Flickr

Here is a pic of the GLCD showing a map of the earth.

So I have tested all hardware functions of the main board. I have found a bunch of design charges that need to be made. Some are my mistakes in layout, others are things I would like to operate differently. Such as contrast adjustment. I will be changing to a different digital pot.

I am currently saving up to order the Alpha PCB's. Hopefully in the next few weeks I will have enough to order the boards and the new parts.

On the side of this project, I am working on a PFC power section. I wil post more on that when Ive made some progress.

Hi Adam,

Did you reverse engineer the VLA-502-01 Powerex driver module?

Is that your own DC/DC, or is the Driver PCB you have shown in your pictures based on the cougar driver power supply ???

Same pinouts as the Powerex VLA-502-01 PCB ???

Looking good !!!

-Mark :D

Hello Mark,

The driver module for the VLA-500 is basically the same circuit that they offer in the BG2A dev kit. http://www.pwrx.com/pwrx/docs/bg2a_application_note.pdf
It has some modifications to the board but not too many. I do plan to add hardware overcurrent protection like in the cougar as well. This will be good for those mishaps.

This will be directly on the main board so it can serve to protect the entire output. it wont matter what driver board is connected, because the pwm will stop before it gets to the driver.

-Adam

[QUOTE=adamj12b;224139]Alright, Here is an update on the charger.



Alright time for some pics.
http://farm6.static.flickr.com/5137/...bc961368_z.jpg
Untitled by AdamBrunette, on Flickr

QUOTE]
Great job Adam!!!
I love the "potassium" power of the bananas in the background..;)

I was thinking that you designed your own DC/DC power supply for the driver section. :o

Adam,

Very nice job on the charger. What are you using for a microcontroller? Any chance you will be posting the software code?

Rick

Hello Rick,

Currently the microcontroller is an AVR ATMEGA128A. This is not finalized though and could change on the Alpha boards.

As of right now, the plan is to release the software. Im trying to come up with an open source charger controller and offer kits for people to build their own either with power stage, or they can build their own.

-Adam

As Mr Bigh said......Great job Adam!!!

I too love the "potassium" power of the bananas in the background, but isn't
that peanut butter on the right and fluff in the middle?:thumbup:

HAHA that is so funny. It really does look like it is. Its not though. Its 2 ceramic pots on the counter.

-Adam

Very clean job Adam - like the interface idea!:thumbup:

Well I have finished all the changes and updates to the rev2 design show above. I did the layout and ordered the boards on Tuesday. They should be here some time next week! Im so excited. This rev3 version is a totally different layout then the rev2 one. Im really pushing the free version of eagle to the max. In rev 3 I changed how the encoder is interfaced to the AVR, I changed the encoder for the knob interface and replaced the 7805 regulator with a switching regulator circuit which increases efficiency and input voltage range for the logic. I also added hardware over current protection to the PWM output section which should help contain any mishaps. The serial connection has been fully implemented onboard using an FTDI FT232Rl converter chip. This is a virtual com port chip which will be easier to connect to modern computers. That is, if you are not wanting to use the web interface over the ethernet. Other then those, there has only been small changes. Some different parts where I was unhappy with the results of the others.

Here is a screen shot of the board now.
http://farm6.static.flickr.com/5021/...0d15f409_z.jpgRev3 Layout by AdamBrunette, on Flickr

And the rev3 schematic.
http://farm6.static.flickr.com/5134/...33cab315_z.jpgrev3 Schematic by AdamBrunette, on Flickr

Im sorry to those that dont like surface mount, but there was no way I was fitting all this on a board in through hole. lol. Hopwever, I do plan to offer front panel controllers fully assembled and tested to those interested.

-Adam

Hey it is not that hard to solder them - even with a regular sharp point Weller iron.. I like to use my nerd goggles (magnifying) to get in close... I have more trouble removing them that way BUT there are tips.... Nice lay out Adam :thumbup:

Adam,

Nice work on the PCB. I used to be in the electronics fab industry. If you are going to assemble these for people and the numbers justify it, you may want to consider ordering a stencil and using solder paste. Even hand soldering becomes much easier. I've ordered 100s, so if you wanted help let me know.

Thanks again for the good work,

John K.

Im actually doing that now! lol. I have a friend with a cnc vinyl cutter that I use to make my own stencils out of mylar film. Its great and free. Then pop it into the taster oven in the garage to melt the solder and done with the smd stuff.

If there is enough interest, I will have my friend with the pick and place machines build them in runs.

-Adam

6Kw DC Charger Controller on wiki
 

This project was added to the wiki: Open ReVolt - EcoModder

-Mark :D

Last night I was able to etch and populate 90% of the board that will be used to measure output of the charger. This board contains a closed loop hall effect sensor thats 0.25% accurate as well as isolated voltage measurement circuit.

My goal with this board is 0-60A and 0-400V all isolated.

The connectors and PCB will be the weak point. However, The circuit board is 5oz and the connectors are meaty. They say they are rated for 30A, but in comparison to other connectors rated to 30A, they are much much heavier. Other connectors have 2 pins that go through the pcb that are the same size as these ones. These have 6 though. Only testing will revele the real current limit.

All thats left to add are the dc-dc converters for isolation that I was not able to afford yet. They are about $15 each... :(

Well enjoy!

-Adam

http://farm6.static.flickr.com/5146/...a5608609_z.jpg
Untitled by AdamBrunette, on Flickr

Hi Adam,

Thanks for sharing the development of your charger project, It's looking good !!!

Question, how does it all go together? How many modules to make up the complete Charger ? (Controller PCB, Display PCB, Current Sensor PCB, IGBT's ????)

-Mark :confused:

Hello Mark,

The answer is 3-4 really.

The display and controller are all 1. The driver module plugs onto the back of the controller board. The current/voltage measurement board is connected with a lead cable to the controller board. This is to keep the high power stuff away from the logic a little bit. Thats all thats really needed to make it work. After this, there will be another power board that will have the power factor correction stage on it. Again, optional. Also, there is another optional line sensing board that will measure line voltage and current as well as power factor and other cool stuff. Thats mostly because i like to see everything thats going on. The controller will calculate line current enough to keep it limited from tripping the breaker.

As for the measurement, If you have a full BMS system in the car, that can measure current into the pack and pack voltage, it could be adapted to work off those readings.

So I guess the final answer is anywhere from 2 (controller and driver) up to 5 (Controller, Driver, Current/Voltage Measurement, Line Measurement, and PFC.

-Adam

Well it was a busy weekend. I got a lot done, but there is still alot left. Starting to worry about making my April 30th deadline with a working prototype.

I was hoping to get the PCB's on Friday and have the weekend to assemble and test them. Turns out they wont be delivered till today...Great... But that also means that the parts i forgot to order came in yesterday so I will have everything I need to put them together in 1 go.

Anyways, I was able to complete the building of the high power driver board. This is the board that uses the VLA-50X modules. Im using a VLA-500 module for now, as it was all I could get my hands on. Mrbigh was kind enough to sell me one of his, as he does not need it before his next order comes in! THANKS A TON!! So I soldered it to the board along with all the supporting passive parts. This board is basically half of the BG2A dev board.


http://farm6.static.flickr.com/5185/...55cf41cc_z.jpg
Untitled by AdamBrunette, on Flickr

http://farm6.static.flickr.com/5021/...b54631d4_z.jpg
Untitled by AdamBrunette, on Flickr


On Sunday I decided to start work on the power section of the charger. My order for high frequency inductor parts came in so I was happy that I could use them during layout of the heat-sink.

I started with the remains of a Yaskawa servo pack for AC servo motors. This was one of the biggest ones I had. It had bad logic, so I didnt feel bad ripping it apart. The drive is from the early 90's. It uses a 60A 3 phase SCR bridge for a rectifier and 3 darlington transistor modules that require 9A base current to turn on! :eek: So I decided to remove them and store them for use probably never. lol I went with a CM400DU-12F Powerex 2-pack IGBT just because I have a bunch of them. 400A is a little overkill. It happend to line up with 2 of the 4 mounting holes of the transistors. I decided to keep the scr bridge for now, and will just turn on the SCR's with the 2V they require and use it as a regular rectifier. The pack would control it to lower the bus voltage. I used 2 AAA batteries before, to activate the scr's when I was playing around build a plasma cutter. It worked well.

Anyways, I got the IGBT and dc output measurement board mounted as well as the inductors positioned where they will be and brackets designed for mounting them. I also decided to use a Kilovac EV200 contactor for cutting the dc output. Again, I have a few of them, and their really good contactors.

So all thats left is to finish the PFC controller and add bus caps. I plan to use a film cap for the bus cap, as their compact and very powerful. The one im looking at can handle 100A ripple! and its only about $96. Compared to using electrolytic's in 35mm diameter, it would cost about $160. Here are some pics of the power stage.

http://farm6.static.flickr.com/5188/...08eae2f4_z.jpg
Untitled by AdamBrunette, on Flickr

http://farm6.static.flickr.com/5064/...0d647627_z.jpg
Untitled by AdamBrunette, on Flickr

http://farm6.static.flickr.com/5148/...d36f42cf_z.jpg
Untitled by AdamBrunette, on Flickr

http://farm6.static.flickr.com/5022/...11a9df73_z.jpg
Untitled by AdamBrunette, on Flickr

I was also able to test the current capability of the measurement board.

YouTube - DC Measurement Charger Board

Well I think thats it for now. I will post more when Ive got the control board built.

-Adam

Well Its been about a month since the EV show in PA. Ive done a little on the charger but not too much. Will be getting back into it very soon.

A few people have been asking be about a circuit for the power stage. Well here it is.

-Adam

http://farm4.static.flickr.com/3202/...be35a392_z.jpg
Charger Power Stage by AdamBrunette, on Flickr

Hows the charger coming?

Things have been crazy lately. With the good weather, comes with the honey-do list. Im working on building a deck, a shed and painting the house....busy summer...

I have been working on the PFC section. I recalculated alot of the values for components and think it should work well this time. Just got to get around to testing it.

-Adam

is the desk built and the shed painted yet?
you own us an updqte on the charger