Bidirectional DC-DC 48v to 400v

[jrbe]

I have a project that will need to pull energy from a 96s ~380vdc battery (1% of the time) then be able to put power back into the battery (99% of the time) that I am doing a bunch of research and testing on. I will respect all of these projects and use none of them if this goes into production. I will also be giving back if this works out. Time is short and its a lot to get this together for testing using existing oem hacked hardware and open source solutions to bridge the pieces together. I can't currently discuss the details of the project past:
- the working voltage will be 12-48v and about 8kw max. of energy generation.
- This 12-48v will have to be boosted to push the energy back into the Leaf pack. It has to stay 48vdc, direct to ~380vdc wont work.
- there may be times the motor controller will be run as a motor to get it moving, then switch to regen mode so a bidirectional dc-dc is ideal.
- I made a 48v GaN motor control board for this (sorry, won't be open source) for the generator side of things that is pin compatible with VESC for testing and future repurposing for/by the DIY community. Max voltage is 100vdc for components but will be kept to 48v in this application. This is the only pc board so far that is meant for this project that's done (but not tested.) The rest will be piecing stuff together to do testing.
- There may be multiple generators with their own motor controllers.
- has isolation between voltage sections
- I do have an isolated 3.3v current sensor rated for +/- 40A on the motor control board for the DC power in / out (a bit under 2kw.) It also has an unpopulated shunt across it so I can adjust the range if needed.

I have spent a lot of time searching / researching / watching Damien & Johu's videos for this bidirectional DC-DC part but I'm coming up short. So where I'm looking for direction / clarity from the group is:

• on hardware I'm thinking late Gen 2 Prius or Gen 3 Prius inverter to use the boost converter - Which would be recommended (or something else)? I have not been able to find enough details so far to help choose which would be ideal. I've seen the boost converter can fail in the gen3 where gen 2 seems bullet proof.
• I think I only need the bidirectional DC-DC / boost converter so the rest of the inverter might be gutted to make room for whatever is needed.
• what inverter connectors will I need for the inverter to use the DC-DC?
• if I have the dc-dc pwm set to say 14v, will anything on the generator side past 14v be pushing back into the traction battery? I think the motor controller running as regen control will be able to control the power output from each generator as the current control.
• I found celeron55's prius3charger_buck software for gen3 Prius. This wont be plug and play for my testing but is a great starting point for this testing.
• Does any standalone hardware exist for running the boost converter? Looks like Damien's gen 3 board has it for celeron's code, any others? I might just do an arduino or spin up a quick board (might have one with some 7 segment displays i could use...) but I'm unsure of 5v? 3.3V? in the boost converter. Most projects / discussion is around AC charging, hard to find info about DC.
• Do i need a precharge resistor for the dc-dc by itself? Plan is to tap off the PDM for the traction battery voltage.
• Anyone know the capacitor value in the boost converter?

Any guidance or different ideas are appreciated!

[johu]

Did you find this one?


it runs bidirectional, because I use it to precharge the bus cap to 600V from the 400V traction battery.

A synchronous converter acts like a transformer for DC voltage. If you set it to, say 1:8 and have 360V on your Leaf pack and 48V on your motor controller then current flows in the direction of the lower translated voltage. So 360/8=45V -> current flows from motor controller to pack.

[jrbe]

I had not seen that video, thanks for digging it up!

Those are gen2 Prius components?

[johu]

Those are gen2 Prius components?

Yes
Rewatching the video I'm not sure why I decided to switch the 5V instead of the much simpler GSDN.

[jrbe]

I'm trying to source a 2009 Prius inverter now. Getting one in my hands will help me work through understanding these things.

I see this video is 3 years old, not sure if its backburner for you or abandoned.
Are you thinking of doing a standalone control board for controlling the boost converter or updating the gen 2 Prius board to add this stuff? I see your gen 2 board in the video but a bunch of other stuff to make this work. I'm going to go the prototype route but will likely make a no spaghetti PCB shortly after so I hopefully don't have to worry about it.

*Edit Or is this something to consider for FOCCI?*

Is is worth using a 328p (arduino 5v processor) for 5v compatibility like on the Damien Gen 3 Prius?

[jrbe]

I got a 2008 Prius inverter and pulled the inductor and igbt out. I need to put them in a different housing to fit this in my project and will need water cooling based on where its located.

I really couldn't find any hardware to run this directly. I'm making an Atmel 328P board to run this along with a 4x20 display. I'll share my results as I make progress on this.

Thanks for the info johu. Your video along with the charging wiki page, https://openinverter.org/wiki/Operating ... pplication helped a bunch to wrap my head around this.

[jrbe]

I just got this running at low voltage for some testing over the last 2 days.

I was able to amplify 20.0v input up to 196vdc at 5khz and 10% duty cycle wired as it is in the Prius.
Flipping the power and the igbt sense wire to CP so input is on CP instead of on the far side of the inductor it reduces power. Using 9% duty cycle is a 10:1 reduction, so 10v in equals 1v out.
Both tests are at low current, testing with a 2k ohm 225 watt resistor at first then I'll move to higher power tests once stable.

There is a 3x power surge when turned off so I'm working on some pwm voltage sense to shutdown the igbt if it senses brownout / power dips too far.

This is using a high side switch to apply +12v to the IPM enable and pwm circuit.
The csdn is turned on after a short wait after pwm starts. This will also be switched off if the pwm supply voltage falls below around 7 volts, the igbt starts glitching / shutting down around there.

I'm only planning on using a fixed ratio for my project. But this could be a great option to move power between DC sources if a current mode is added. I was also thinking about a mppt mode with limits but won't be doing that.

This is using an Arduino R4 WiFi to transmit data over ble. Also might add a sparkfun 20x4 LCD if I have time.

Not sure anyone is interested but wanted to share my progress so far.

[johu]

Oh wow, I totally missed your updates on this. Sounds very cool.
If I remember correctly the only external component that is really needed is an npn transistor to run the PWM. Then you can use pretty much any processor you like.

This is now interesting for me as well, I am toying the idea of hooking up my 12S battery to the HV Sungrow inverter (the one I use for V2G) instead of using the separate flatpack and Soyosource inverter.

This would open up some new options, e.g. actually precharging the inverter to the cars battery. Most of all it would allow putting the inverter in running state so it can deliver or draw power right away, without the 2 minutes wait period.

Not sure about the efficiency. Internally the inverter works with 600V and also has a boost converter. Not sure which variant is better: The Prius converter taking it to 400V and the rest is done by the internal booster or the Prius taking it to 200V. Then one runs at 1:4 and the other at 1:3

[jrbe]

Nice, I'll share files on GitHub once done and tag you here when I post them.

I did test 4% duty cycle, it ends up around 16.5:1 but the closer to 0 the less power I'm assuming will be able to flow at some point. That could also work out well for soft start requirements. Part of my projects requirements are a soft start to limit inrush to charge capacitors so I'm planning on setting a starting pwm then a ramp time to target pwm if it's not a disaster trying to code.

The R4's Renesas processor has it's own way of doing a bunch of things so the code i share will be pretty skewed towards working with that. I wanted wireless data transfer because of the voltage ranges so that was the quick and fairly cheap solution.

I see a lot of possible use cases for this.
My understanding is the Prius gen 2 is a 1200v igbt. That opens up a lot of possibilities.

The one kind of oddity is that one side will always be the low side and the other will be the high side. My initial assumption was that it didn't matter.

I do have an 850v isolated voltage sensing circuit for both sides of the converter already on the PC board I made. That could also be used in interesting ways in a current control mode. The R4 has a 14 bit ADC and the resolution should end up a bit over .05 volts. There are also dual footprints for current sensors for flexibility, using HO25P and HO100P current sensors for mine.

I have a v0.0.1 started that I'll be swapping the silkscreen to high voltage and low voltage as well as fixing a few things.

The 1:100 igbt voltage reference output is not running as I expected or maybe I damaged mine in testing.

I also had a very humbling experience running a contactor to try to economize it. Lots of heating issues as well as a surprising amount of duty cycle to hit their sweet spot, I think because of their inductor like blocking behavior.

And thanks to you johu and others who shared info about this Prius bidirectional converter. This project would have been much more difficult if I had to start it all from scratch!

[Tirediron]

I recognize this thread is over a year old but it fits my question perfectly. Is there a converter out there that will work with a Growatt MIN10000TL HX-US Solar Inverter? Apparently the Growatt has a unique BMS that is proprietary and there is no way to use ordinary 48 volt batteries. It seems that they developed a "BDC" product, but it is made of unobtanium. Thanks for any assistance you can provide

https://www.austraenergy.com.au/upload/ ... manual.pdf


https://www.portable-sun.com/products/g ... 00tl-xh-us

[jrbe]

Is there a converter out there that will work with a Growatt MIN10000TL HX-US Solar Inverter? Apparently the Growatt has a unique BMS that is proprietary and there is no way to use ordinary 48 volt batteries.

Your question seems to be more about the BMS and it's locked down communications to the inverter. This thread is about a bidirectional DC-DC.

There are some projects on GitHub using EV batteries with different inverters with can / rs485 translaters. This is not one of them.