Range extender charge pump

[arber333]

I still have desire to extend range for Ampera car. I have made a test Y cable to access battery and i intend to install it soon.
Really this could be extender for just about any EV, even Prius. Only condition is to have direct access to battery. I would like to achieve that through Y cable between HV battery and inverter. This means car will have to be on while transfering charge. Car system will think regen is happening.

I would still need a control brain for the charge pump with two voltage comparators and some hysteresis. Current would be adaptable through code.
It could also use Wifi or 3G module to report status online.
Really in hardware i would actually just use a rev1 or rev2 board i still have here and dont use anymore.
If you are interested you could correct in the code and correct some I/Os from inverter brain and use it for voltage control loop for charging purpose. If we set this correctly we could even use this as house chademo charger or solar controller etc...
Later on i can present my formation of parts and process.

What i am proposing is to finance charge pumps software development (up to reasonable amount), hardware is already available and i will provide test subject/object... Someone might join us and in the end we could publish working design as DIY.

To everyone interested... this could also make excelent 22kW Level 2 charger.

[arber333]

I picked up the idea here http://www.wolftronix.com/buckBoost/index.htm

I have some parts from Prius inverter, namely DC link capacitor and inductor. Those are adaptable to my system directly.
Also i have one 400A IGBT with watercooling pad and two 400A current hall sensors.
I have two panasonic 300A DC contactors for DC or AC side.
Also i have one inverter brain Rev 2 from Johannes that i could use for charger control loop.
I could use two sense boards and connect them to brain board

It would not be a problem to assemble everything together in a box to try it on my EV.

What i need is software that would control the main board to use the input (for example 60Vdc battery in a trunk) and boost that voltage to 360Vdc in a car or a house etc...
While one side is evidently present as the wiring for boost charger on Johannes site, the other side would have to be attached to some of the inputs of existing board. We could change input for example throttle input for sensing voltage and regen for sensing current on the 2nd battery side.

Charge converter/pump would start with ignition (enable signal from DCDC converter in Ampera). It would then be dormant until voltage of main battery would reach some minimum where pump would start its function. Concept of control would be continuous loop where charger would try to follow one reference. That is voltage of main battery. 2nd battery would then be depleted down to some value where proces would stop and converter would wait for recharge.
Recharge could then be started by plugging converter to 3phase voltage (car is parked) and two connectors would disconnect main battery and connect AC input! Then the reverse process would start. Voltage over 500Vdc would go into buck side of converter and on the other side regulated 60Vdc would come out untill 2nd battery would be full. Very Prius like.

I recommend next inputs to be changed in software:
Throttle input becomes 2nd battery voltage sense input
Regen input becomes 2nd battery current sense input
Start pin would accept 12V enable signal
BMS input would be used to signal if battery is high or low
Presence of AC or DC voltage (Buck boost direction) would be indicated by FWD or REV pins.

Any other suggestion for SW change?

A

[johu]

Sounds like some reasonable effort. A first shot of the software should only take me a few hours. Can you do the first tests with the regular firmware to see how the car likes it?

[remy_martian]

I'm scratching my head on how this "extends" range.

From what I think you're trying to do, you'll actually DECREASE the range.

Before resources get consumed on a possible boondoggle, please explain how range is extended here.

[nailgg]

I'm scratching my head on how this "extends" range.

From what I think you're trying to do, you'll actually DECREASE the range.

Before resources get consumed on a possible boondoggle, please explain how range is extended here.

Welcome to the forum @Remy

Arber's plan is to put an extra battery pack of 60V in the trunk, and transfer the energy in the extra pack to the main pack while driving. That would be surely useful for a trip where you need a range 50-100 kilometers more than your actual battery capacity can handle. What's the point that makes you think that it would decrease the range?

[arber333]

[/quote]

Arber's plan is to put an extra battery pack of 60V in the trunk, and transfer the energy in the extra pack to the main pack while driving. That would be surely useful for a trip where you need a range 50-100 kilometers more than your actual battery capacity can handle. What's the point that makes you think that it would decrease the range?
[/quote]

Well that would be exactly my plan. However extra battery voltage may vary, i would be willing to use like 4x Tesla flat modules connected in series. Ampera has enough room in the back to even fit those modules under the rear or inside trunk space. They would be wired in series 4x 24V = 96Vdc.
I would use Prius inductor rated at 25kW and a prius double cap with a halfh bridge 400A IGBT.
System would also double as a charger. If i connect AC 3phase to the HV side of charge pump, system would disconnect HV battery and provide 580V for charging (buck mode) into 96V battery in the rear. That would eliminate need for additional charger in the rear.

Yes car would need to be on at the time of energy transfer from rear to front, but that would happen during driving anyway.
Really this would work to extend range on any car where we could connect charge pump to the HV battery somehow. Also it could work to quickly charge a car from solar battery in a house system.

First as a proof of concept i could just remove 60Vdc of battery from front of Mazda and put it in the back with charge pump. Then i could experiment without lessening my everyday range if experiment is not successful at the time.

[remy_martian]

I'm scratching my head on how this "extends" range.

From what I think you're trying to do, you'll actually DECREASE the range.

Before resources get consumed on a possible boondoggle, please explain how range is extended here.

Welcome to the forum @Remy

Arber's plan is to put an extra battery pack of 60V in the trunk, and transfer the energy in the extra pack to the main pack while driving. That would be surely useful for a trip where you need a range 50-100 kilometers more than your actual battery capacity can handle. What's the point that makes you think that it would decrease the range?

Thanks for the clarification, both of you. I got confused with the use of "charge pump."

1) It's an extra 100kg to carry in the car, which is a 5% hit on rolling resistance for the full drive.
2) A "boost converter" (it's not a "charge pump" with an inductor in the circuit) is not 100% efficient -- at best another 5% hit on the added energy.
3) Switching between buck and boost modes carries another hit in losses

I think you're better off slicing and dicing the extra pack to get the voltage up to nominal system levels and just switch a contactor in and out. Makes charging a lot simpler as well.

K.I.S.S.

[johu]

1) You mean the charge pump will be 100kg or the extra pack?
2) Indeed, maybe more, see below
3) No. A boost converter (using a half bridge IGBT module) in one direction is a buck converter in the other direction. No added losses here

You do have a point with the difference in voltage. 60V to 360V will be quite lossy in a transformerless design. I'd expect 85%. It still yields added range of course. Added capacity*85%

[arber333]

[/quote]

Thanks for the clarification, both of you. I got confused with the use of "charge pump."

1) It's an extra 100kg to carry in the car, which is a 5% hit on rolling resistance for the full drive.
2) A "boost converter" (it's not a "charge pump" with an inductor in the circuit) is not 100% efficient -- at best another 5% hit on the added energy.
3) Switching between buck and boost modes carries another hit in losses

I think you're better off slicing and dicing the extra pack to get the voltage up to nominal system levels and just switch a contactor in and out. Makes charging a lot simpler as well.

K.I.S.S.
[/quote]

Yeah, but my concept would be used to extend the range of a production hybrid cars. Where we do not have direct access to the primary battery. It would also be possible to extend range for older EVs too. The easiest way to approach that is by connecting another battery to the inverter DC cables then. You would have control of triggering the extender DC contactor by observing voltage of main battery after EV power on. Then to keep control of the charge flow you would need either buck or boost application. Most trunk extender batteries would be low voltage (nonlethal) i imagine.

1. It is not about 100% efficiency so much than the availability and capability of the charge pump to control the correct power flow. I dont think that could be arranged by using "exactly" the same battery voltage. I have already tried that. Batteries had similar voltage, but were of different chemistry. I got huge currents between the two, which were not observed by EV instruments. I observed them by chance when i used my handheld current meter...

2. I would not stop only at boost. I would like to use it as buck from the other side also. I dont mind performance loss as long as it is manageble - cooling etc...

3. I am not sure if those modes would transition in real time. I would be happy if system could be used as a range extender while car is driven and as a charger while car is parked at 3ph charging station.

If you consider lame single phase chargers most hybrids use i would expect most owners will be happy if they can use this system to quickly charge either the main battery or the extender pack and use it to get even more range vs time spent at the chatge station.
I dont know, i can judge by myself only. I know that Volt/Ampera goes for 50km and then runs on gas. I would be delighted if i got at least another 50km from this system since that would make it a every day EV for me.

[johu]

So as a start I'd suggest you wire up just one half bridge module on, say, PWM1 output. Add the inductor to have boost in one direction (extension to car) and buck in the other (car to extension). Put one current sensor on output, one on input. Use two isolator modules. Most important is voltage on car side as it decides the direction of energy flow. Input voltage isn't even so important because you need a BMS to avoid over/under charging.

Other input would be enable input. I think charge/discharge threshold voltage must adjusted with changing SoC. So 4 parameters: chargestart [V], dischargestart [V], chargecur [A], dischargecur[A]. And of course miscellaneous parameters for tuning.

For charging from 3-phase you'd either come up with something separate or swap input and output of the converter using relays.

[arber333]

So as a start I'd suggest you wire up just one half bridge module on, say, PWM1 output. Add the inductor to have boost in one direction (extension to car) and buck in the other (car to extension). Put one current sensor on output, one on input. Use two isolator modules. Most important is voltage on car side as it decides the direction of energy flow. Input voltage isn't even so important because you need a BMS to avoid over/under charging.

Other input would be enable input. I think charge/discharge threshold voltage must adjusted with changing SoC. So 4 parameters: chargestart [V], dischargestart [V], chargecur [A], dischargecur[A]. And of course miscellaneous parameters for tuning.

For charging from 3-phase you'd either come up with something separate or swap input and output of the converter using relays.

I already have it wired like you are saying. I just need to decide how much of a battery will i use on one side. The other side will have Mazda LiPo 102S battery. Also we have to decide whick pins to use on mainboard for what purpose.

So for clarification on system:
I will use one DC switch to disconnect the charger from the car battery.
I will use one AC switch to disconnect 3phase from the diode bridge, But the diode bridge + side will remain connected to DC contactor inside charger.
Negaitve side will remain connected. Hm do you think it wise to use another DCswitch to disconnect the negative side of HV car battery while charging too?
I will put a sensor board with voltage sense to car side, sensor Il1 to car side and Il2 to battery side.
You have a point with simplifying system inputs. If we already know the parameters of extender battery voltage we can get away with a digital input of BMS port.
We would also require Enable pin. That would be 12V from Ampera DCDC enable pin which is triggered by ignition.
How do you intend to track SoC? I agree on voltage parameters but i recommend adding some margin since at different loads main battery will respond differently and you may see some push-pull in transition.

For clarification on operation:
Dont you intend to code this to work both ways?
I would like to use this example; When HV car battery achieves value that we consider 2/3ds SoC we start discharging extender and stop when chargestart value is achieved. I will use 3phase so chargestart will allways be higher than discharge. We can also override other modes with ACpin that would signal AC is connected? That way we dont have to switch cables, only mode of operation.
Since we will not care about extender limits we could just input the maximal voltage we expect on the extender end. System could calculate what duty to use then. BMS pin will signal stop on both ends.

Therefore i propose additional parameter Extendervolt [V] that will allow me to modify the extender battery and its limits.

What say you?

[D@F]

i think the idea is pretty good, as lot of people now have a "power wall" at home.
that power wall could have the fonction of range extender when you need it , and could stay at home for every day ...

[Jack Bauer]

Count me in on this. I can even fund a few hours of Johannes's time if needed. One auxilliary application is to use the Toyota inverters for single and 3 phase AC mains power generation. The booster could be used to bump a 48v battery up to HV for the inverter to then generate AC at any mains voltage. Another application is allowing the use of lower than normal dc battery voltages in conversions.

[arber333]

Count me in on this. I can even fund a few hours of Johannes's time if needed. One auxilliary application is to use the Toyota inverters for single and 3 phase AC mains power generation. The booster could be used to bump a 48v battery up to HV for the inverter to then generate AC at any mains voltage. Another application is allowing the use of lower than normal dc battery voltages in conversions.

The way i see this we can connect 3phase AC to MG1 inverter outputs. Diodes will rectify AC to 600Vdc inside main cap. Then we take boost/buck module and use it to stabilise and buck voltage down to battery voltage. This would be preconfigured charger section. M2 section would drive our motor whatever it is and DCDC would power 12V rails.
Another application would be to connect another battery to the two phases of MG1 and use it as a charge pump like i said.

Third application would be BOTH!!! When we drive, rear battery would be connected in boost mode and when thee charger 3phase would disconnect rear batt and run it in buck mode.

I have to build my charge pump to try it first. Maybe it would e easier and cheaper to just get on Prius inverter...

Do you think DCDC would cooperate with 360Vdc?

[johu]

I'm a bit worried about the connecting 400V 3-phase to an OEM inverter. Ain't they all using 600V parts?

[Jack Bauer]

1200v in the toyota inverters

[arber333]

1200v in the toyota inverters

Did you found out how much Amps can they withstand too? It would be nice to know. I see only a motor rating there. Its 60kW, but at NiMh 200Vdc that makes just shy of 300A? You think it could make more?

[johu]

I've started a new project. Basically copied the motor controller project and cleaned out everything that isn't needed for the DC/DC converter.
I will do the current regulation with a PI controller in PWM routine which will result in lower stationary offset.

[johu]

I started a wiki page for the project: https://openinverter.org/wiki/Charge_Pump

[nailgg]

So what needs to be done to make this be usable while driving? The current demand might change very rapidly during a trip, so with momentary power surges through the inverter might result in some voltage drop in the battery, or the opposite case is possible too with regen. Thus, unpredictable things can happen between the range extender and the battery pack.

I was also planning to develop a hydrogen fuel-cell based range extender with some hysteresis current controller, but I was planning to make the main control hardware based with some comparator logic for acting fast on different momentary battery voltage conditions, while using an MCU to set the current reference, monitor battery voltage to enable/disable the charger etc.

[johu]

Actually I anticipate the changes in current and therefor pack voltage of the "host" (being the vehicle thats range extended) to be much slower than the 8 or 17kHz control loop can handle. Even putting your foot down hard will take like 50-100ms physically.

I would follow the good 'ol approach "start out simple, complicate as needed".

[nailgg]

Nice approach, as always but with the PI control method, we need to take the settling time of the PI controller into account as well. The settling time would differ not only with the PI parameters but also with different inductor values, DC-link cap value, host voltage etc. so careful tuning of the parameters are important for safe operation. Anyway, this could easily be used only when the car is stationary where the system response time is not very important, and could be improved for enabling safely charging while driving too, even auto-tuning of PI parameters could be implemented.

I'm excited to see how this will progress

[arber333]

Hi i was dealing with my inverter sorry for delay...

I expect current output to be limited by Imax parameter that can be set in code.
For example I dont intend for this to exceed 20kW power since i will use Prius inductor. I expect main battery will be able to compensate in case car will need more power. Therefore for start this should be CC system not CV. I expect current to be held at certain level and be tapered at some voltage level before EOC. That way in case of large load CC can be automaticaly increased if voltage sags. Johannes you can can still vary the code later.

In charger mode this will ONLY charge additional battery in the trunk. That way we can have a form of fast charging of the rear battery to be able to go on our way quickly. This would definitely be an improvement for those older EVs or HEVs that only have 3kW charger.

[arber333]

Hi Johu
I had some time to think about charge pump hardware and how to couple this to Prius gen3 inverter.
I see several possibilities and i would like to ask for some explanation of your contact table in wiki.
Lets standardize some things....

1. Assume we will be using STM32 blue pill chip
2. We will only use this as charger, not motor controler, therefore i will activate only buck/boost module
3. Original current sensors i think replacing in favor of 5V ones.
4. Power supply will be standard 9V - 30V buck down to 5V
5. Drivers are integrated in Prius inverter and need only 5V(3V3) signal
6. I will setup the board so it will work with 12V converter if battery is in range.

Now come the questions:
1. Will we only use two PWM pins? Which one do you think to use for Buck and for Boost side? EDIT: i see you declare PWM1 channel in wiki. Does that mean PWM1L goes to DC BOOST LOW and PWM1H to DC BOOST HIGH?
2. How many current sensors do you think i will need? Only one or two? One on MG side and one on battery side? I think i can hide one sensor on battery side, but i will have to think how to measure current on MG side (rectified current that is).
3. How to connect HVDC side (MG contacts)? Ie. will i connect +360V battery to contact L1 which has current sensor and -360V battery to contact L3 which does not have current sensor? Then when we use 3phAC system is assumed to be simetrical, but with DC do we connect current only on one line?
4. Voltage inputs i will just make as variables with 3V3 resistor divider yes? But in code we will have to calibrate range and gain for both.
5. Wifi integration... will this work directly as in any inverter?

Any sample of code to try with blue pill? At least only as buck charger?

EDIT2: i prepared a schetch of bluepill contacts. Can you verify or correct me? Some of the pins from wiki i couldnt fit on bluepill. Can you suggest what to use for: AC contactor, HV contactor output
What is LV/HV Output? Is it an interlock relay function meant to tell inverter when to buck or boost?

tnx

[johu]

The project might see a revival this or next year. I would like to extend Touran range with some random battery in the trunk. As we have dropped the Blue Pill for new projects it will require V1-V3 main board.
Prius buck/boost stage is one option, reviving my TO-247 IGBT modules would be another (allowing higher frequency). Even SiC could be interesting to keep the cooling noise down and have even higher switching frequency and a tiny inductor.