Solar Catamaran 45ft with dual Leaf motor

[yabert]

Hi

I'm looking to a way to use 2 Leaf motors to move a 45ft Cat.
I have experience with conversion, EV and battery in general, but not much with hacking controller.
https://www.thesamba.com/vw/forum/viewt ... ?p=9146376
http://www.evalbum.com/4155

So, my goal is to have two 10-20 kW motors spinning propellers (around 1000 rpm) in a 45' Cat with a 16S NMC battery (58V nominal) and around 150-170 kWh.
I first tough about using Motenergy ME1507 permanent magnet motor with a typical 72V controller (I have ASI BAC 2000). Then I realize that a Leaf motor can spin sensorless with my 72V controller (actually tested).
Then, I realize I can maybe use Leaf motor and controller for this project despite the low voltage input.
I'm a bit noob about electronic and programing, so if my goal is possible, can I know how to do this and where to start?
Let me know. Thanks

[tom91]

Why that low a voltage? You will not get that sort of power out of the leaf motor and inverter at that voltage.

Even if you use an open inverter board in the nissan leaf inverter, to allow such a low voltage.

[yabert]

Why that low a voltage?

To stay compatible with all the popular 48V solar stuff (MPPT, charger, inverter, etc).

Even if you use an open inverter board in the nissan leaf inverter, to allow such a low voltage.

Interesting!
Simply based on the motor, if a 40 lbs motor (ME1507) can output around 10 kW continuous at 58V, then a larger 120 lbs Leaf motor can output 10 kW continuous. No?
About the Leaf inverter, sure I don't know.

[tom91]

larger 120 lbs Leaf motor can output 10 kW continuous

Yes it can. but you want to run it at 58V... it is designed for 350V

So no idea what the rpm/V curve is. There is now way it will make 10Kw on 58V.

[yabert]

So no idea what the rpm/V curve is

What I found is this data and this graph.
With 1/6 of the voltage I don't know why it could not output 1/6 the power.

[johu]

Here's my take on it. At 350V it can output 160 kW and it will run in field weakening above around 4500 rpm.

So you would think, ah, no problem at 58V it can do 26 kW at 750 rpm. Thing is it can only do so short term as it runs around 400A per phase. Half that, *may* work continuously. I wouldn't go as far as saying no way here but it's a gamble.

Romale here on the forum runs it at pretty low voltage I think, maybe he can chime in

for understanding: the battery voltage in this experiment is 45 volts, the load on the motor shaft is 0 (gearbox only)

[yabert]

So you would think, ah, no problem at 58V it can do 26 kW at 750 rpm. Thing is it can only do so short term as it runs around 400A per phase. Half that, *may* work continuously. I wouldn't go as far as saying no way here but it's a gamble.

This is exactly my thought. And that ''may'' work perfectly for our solar boat.
Do you think this can be done with the Leaf controller?

[johu]

I'm pretty sure the stock control board won't run at that low voltage, so board swap is your only option. Some chance I'm wrong

By controller you mean https://openinverter.org/shop/index.php ... duct_id=57 ?

[yabert]

By controller you mean

Yes.
I should have written: Do you think this can be done with the Leaf controller + openinverter control board?

[tom91]

done with the Leaf controller + openinverter control board?

No one knows, you have to try this yourself if you want to know for certain.

[johu]

Just wondering would it be possible to split the battery into multiple 58V modules that each have their own MPPT controller, then put them in series for the motor?

[yabert]

split the battery into multiple 58V modules that each have their own MPPT controller, then put them in series for the motor?

Sound like the best way to end with batteries at different SOC
Really, I don't need high power because anyway I will not have a lot of energy, and I also don't need high RPM, so low voltage is simply perfect for this application.
I bet I was a bit too excited at diching low voltage and low/medium quality controller and have high quality rugged Leaf controller

Is there also chance that efficiency of IGBT in 400V controller working at 58V will be lower than mosfets inside 72V controller?

[Zieg]

Yeah you're gonna have losses. And if you run it at 20kw continuous, then you'll be pulling nearly 350a continuous? That's some big wire.

[johu]

Is there also chance that efficiency of IGBT in 400V controller working at 58V will be lower than mosfets inside 72V controller?

Did a quick parametric search and 100V FETs seem to be around 2mOhm. So at 400A it'll drop 0.8V where an IGBT will always drop around 2V. So yeah, at least double the losses. Also what I observed in various experiments. MOSFETs almost did not heat up where IGBTs did.

Sound like the best way to end with batteries at different SOC

Yeah, brainfart on my side

[yabert]

So at 400A it'll drop 0.8V where an IGBT will always drop around 2V. So yeah, at least double the losses. Also what I observed in various experiments. MOSFETs almost did not heat up where IGBTs did.

This point alone will probably keep me away from the Leaf inverter and the openinverter control board.
The boat should have 30-40 kW available from 2 motors for short burst, but the reality is it will move the majority of time with 5-15 kW from one or two motors.
Low speed is key to have range.

Still, the Leaf motor look like a good contender for this project, but I have now to find proper 72V controllers. Suggestions?

[johu]

Did you check out the VESC project?

[Bratitude]

Why not just run a Hv mppt? And have a hv pack

[arber333]

Huh... Why complicate things? You will be running prop shaft and propeller with it no? Resolver is redundant there as long you dont need absolute position of the blades.
Leaf motor is PMSM...maybe you can test just ordinary PMSM mosfet inverter. You can get 10kw inverters off the shelf for low voltage.

I remembrer testing chevy volt inverter with 48V and its power stage turned on above 42V.
It has TWO symetrical power stages capable 600A in one case. Perfect for symetrical loads.
With it i used dual Lebowski brain in sensorless mode and Leaf motor had no problem running with wheels off the ground or two motors on the same inverter for that mater ..but for car start i needed at least 3 hall sensor input.

I think someone showed (romale) Honda IMA inverter works with low voltage as well...

[johu]

They work with low voltage just with lower efficiency than low voltage mosfet inverters

[yabert]

VESC project?

Wooh! Sexy, compact and affordable for the 75V 300A. Thanks to share.
Can probably output the 5-10 kW continuous/ motor for your needs.
Those will spin a Leaf motor without too much challenge? Sensorless? Resolver signal?
Also, based on a 58V battery (up to 66V) is it better to pick the 100V or 75V inverter? Question is based on '' Voltage spikes may not exceed 75V!''

[yabert]

Why not just run a Hv mppt

I'm open to suggestion.
But from what I know, reliable stuff only exist for 12V-48V.
I know there is HV inverter with integrated MPPT, but it's clearly not a way I would like to go.

Then, with an HV battery, MPPT is a challenge, but also inverter, charger, fuses, etc.
If you add the fact that salt water and high voltage increase a lot the danger, stay at 48V seem wise to me.

[yabert]

Resolver is redundant there as long you dont need absolute position of the blades.

Yes, a prop in the water don't need great torque control.
So, sensorless can work fairly well according to you?

[arber333]

Yes, a prop in the water don't need great torque control.
So, sensorless can work fairly well according to you?

Well Lebowski operates on hall sensor 6step untill about 100rpm then it switches to sensorless where it "sees" stator coil discharge spikes which it uses to sense where the magnet went past. This works so good i never had any "conk out" while driving on the highway (doing burnout at 100km/h) even though i had some conkouts with high current driveoff.
Here is some of my history with Volt inverter, you can find some relevant posts here at this forum as well...
https://leafdriveblog.wordpress.com/tag/inverter/

With Lebowski brain I use UVW encoder from RLS company which simulates hall sensors signal
https://leafdriveblog.wordpress.com/201 ... n-encoder/

However you can also use Openinverter brain with resolver interface which Johannes developed. I think for propshaft you cant go wrong...
https://leafdriveblog.wordpress.com/202 ... controler/
https://leafdriveblog.wordpress.com/202 ... r-running/

Some of my other tests with dual motors

[arber333]

Wooh! Sexy, compact and affordable for the 75V 300A. Thanks to share.
Can probably output the 5-10 kW continuous/ motor for your needs.
Those will spin a Leaf motor without too much challenge? Sensorless? Resolver signal?
Also, based on a 58V battery (up to 66V) is it better to pick the 100V or 75V inverter? Question is based on '' Voltage spikes may not exceed 75V!''

Yes OEMs usually rate inverter by transistor ratings. And they choose those by [max system voltage] * [1.5] safety factor because of reverse diode spikes. Some may even go up to 2 in safety... so for 320Vdc nominal you can get awaya with 600V transistors but for 420Vdc system you may need 650V rating or more...

I see they rate 300A VESC as Voltage 25V-75V which means safety is already included. They talk aboout 18S LiPos!!!

[jrbe]

Wooh! Sexy, compact and affordable for the 75V 300A. Thanks to share.
Can probably output the 5-10 kW continuous/ motor for your needs.
Those will spin a Leaf motor without too much challenge? Sensorless? Resolver signal?
Also, based on a 58V battery (up to 66V) is it better to pick the 100V or 75V inverter? Question is based on '' Voltage spikes may not exceed 75V!''

The leaf motor will do much more than that voltage in regen. There are high voltage options for vesc but not off the shelf, diy route, some shared. It's also a very low ohm motor for a common vesc. I'd be very surprised if an off the shelf vesc lasted very long driving a leaf motor.