12 kw rc motor

[Jeremy Harris]

You're not going to find a sensorless controller to do it any justice.

There isn't a sensorless controller available that can even do the 1/3rd the size HXT motor any justice.

Get one of those motors to Jeremy or Burtie, and they can figure out a sensor position/solution for it, and then it can be used properly.

RC controllers are for toy motors in 10lbs toys. This is not a toy motor.


As far as the people asking about bigger phase leads, that would just require doing a higher KV wind. They just pair the phase wires up in delta and run them out of the case on RC motors, so the wire size is determined by the winding dimensions, which are of course determined by the number of winds.

I'm already working on a controller, Luke! I've been doing a lot of work recently on building a small, high current, controller. One thing I discovered, when looking through dozens of FET spec sheets, is that there are some surprises, as a big package isn't necessarily the best. Some may have spotted that getting heat out of the FET junction is the big issue that limits the current a single FET can handle. There's nothing much that can be done about the internal thermal resistance, and this tends to be similar for pretty much any package. The big packages offer the means to get heat out of the package more easily, but this can be done another way, I think.

I've found this FET:

IRFS3107-7ppbf.pdf

(315.27 KiB) Downloaded 230 times

Yes, it's a small, surface mount package. BUT, look at the ratings and then think about this as a mounting option:

What if the power rails and the phase connections were solid copper bars, connected to internal finned heatsinks?

What if the FETs were soldered directly to the copper bars, providing not only a good electrical connection, but also a near-zero thermal resistance (no insulators needed)?

What if the controller had a small internal fan to keep the "live" heatsinks cool?

I'm thinking of a 12 FET power "board" using these FETs, driven by a 6 FET controller board. I reckon such a controller would comfortably handle well over 200 amps. In fact, in might well do around 150 amps on just 6 FETs. The downside would be the 75V FET Vds limit, but as the motor is rated at 60V max this shouldn't be too big and issue.

Any thoughts?

Jeremy

[bigmoose]

Jeremy your idea is good! It is exactly the direction I was headed, and I was spec'ing the D2Pak 7Pin package also. As they say, "Carry on!"

I was looking at the 100 Volt version: IRFS4010.

An other facet I was thinking about was to remove all the spaghetti from the "power head" of the controller and run a serial link to a handlebar "data/control module" That way the PowerHead only get battery busses, 3 phases to motor, hall leads, and a 3 or 4 wire link to the DataControl module. All the rest of the spaghetti/connectors would then be right in the handlebar area.

[jag]

What if the power rails and the phase connections were solid copper bars, connected to internal finned heatsinks?

What if the FETs were soldered directly to the copper bars, providing not only a good electrical connection, but also a near-zero thermal resistance (no insulators needed)?

What if the controller had a small internal fan to keep the "live" heatsinks cool?

I'd say solder thick and wide copper power bus to source and drain (ben the gate up a bit). Then a thin insulating sheet between the copper bars and a regular passive heatsink. Remember total thermal resistance of this insulating sheet = k/contact area. the contact area of the copper bars can be made arbitrary large, so the negative impact of an electrically insulating pad can be made much smaller than when it is attached directly to the FET. This is why newer CPU's have heat spreaders inside the package.

Even more compact: Design the controller PCB to match the slightly bent up gate pins, then attach power bar and heatsink assembly with small risers. A bit of a pain to manually solder the FETs this way, but I think I have managed more tedious ones...

[12p3phPMDC]

THose 7 lead d2paks do look impressive. lots of good ideas here.

Keystone electronics makes some great little phenolic standoffs with threads that you can use
to isolate a direct copper bonded assembly if you want to float it within the case.

I just got some samples to isolate the ground leg of the shunt from the heat sink.

[swbluto]

You're not going to find a sensorless controller to do it any justice.

There isn't a sensorless controller available that can even do the 1/3rd the size HXT motor any justice.

Get one of those motors to Jeremy or Burtie, and they can figure out a sensor position/solution for it, and then it can be used properly.

RC controllers are for toy motors in 10lbs toys. This is not a toy motor.


As far as the people asking about bigger phase leads, that would just require doing a higher KV wind. They just pair the phase wires up in delta and run them out of the case on RC motors, so the wire size is determined by the winding dimensions, which are of course determined by the number of winds.

I'm already working on a controller, Luke! I've been doing a lot of work recently on building a small, high current, controller. One thing I discovered, when looking through dozens of FET spec sheets, is that there are some surprises, as a big package isn't necessarily the best. Some may have spotted that getting heat out of the FET junction is the big issue that limits the current a single FET can handle. There's nothing much that can be done about the internal thermal resistance, and this tends to be similar for pretty much any package. The big packages offer the means to get heat out of the package more easily, but this can be done another way, I think.

I've found this FET:

IRFS3107-7ppbf.pdf

Yes, it's a small, surface mount package. BUT, look at the ratings and then think about this as a mounting option:

What if the power rails and the phase connections were solid copper bars, connected to internal finned heatsinks?

What if the FETs were soldered directly to the copper bars, providing not only a good electrical connection, but also a near-zero thermal resistance (no insulators needed)?

What if the controller had a small internal fan to keep the "live" heatsinks cool?

I'm thinking of a 12 FET power "board" using these FETs, driven by a 6 FET controller board. I reckon such a controller would comfortably handle well over 200 amps. In fact, in might well do around 150 amps on just 6 FETs. The downside would be the 75V FET Vds limit, but as the motor is rated at 60V max this shouldn't be too big and issue.

Any thoughts?

Jeremy

If you can successfully mount/solder it to a large heatsink without killing the fet AND have a powerful fan providing airflow, I'd say you got yourself a winner. I use a CPU fan with heatsink on my ESC and it stays *amazingly* cooler when blowing air than when it isn't. (Like the difference between 10 degrees above ambient and 130 degrees.) The closer the air flow is to the fets, the better.

[Jeremy Harris]

I guess I could bolt the big copper bus bars to an external heatsink, using insulating pads, but I rather like the idea of internal fan cooling. I think this motor is probably going to need forced air cooling if it's run enclosed/semi enclosed on a bike, anyway. One option might be to build the controller into the motor mounting housing, fit a fan on the end of the motor and have a neat unit that houses the motor, controller and something like one of Matt's reduction drives.

This would make installation and wiring nice and easy and it would reduce the I²R losses on the controller to motor phase wires (which can be high, as the phase current peak can easily be two or three times the battery current). A module that just bolts in, with a drive shaft suitable for direct connection to a final drive on one side, a couple of hefty power feed wires, a three wire throttle connection and maybe an ebrake connection would make for an easy to use power unit. Using the motor as the means to turn the fan removes the potential unreliability of a separate cooling fan.

Whilst I can probably put together the controller and maybe prototype the drive module, if it works it might be just the sort of this for one of our budding parts producers to look at making. It'd be nice to have a CNC machined housing holding everything and looking cool as well.

Jeremy

[Timma2500]

Wholly snapping duck shit i MUST have one of these beauties!!! Luke forgets about
160km/hr e-bike 200km/hr babeee! Lets see those frock motor boys catch this bad boy

Who do I paypal?
.

^^Ditto

KiM

Yep that pretty much sums it up! Hmmm single speed, direct drive to back wheel with maybe around 3:1 - 5:1 reduction depending on voltage used.
Simple, neat, monstrous!
Awsome find! Now to find a controller with big enough balls to run it lol
Sounds like work has began on that front


Paul

[markobetti]

i will have sensored - same motor on 14 of april

[12p3phPMDC]

Markobetti,

Fantastic!!

If you can request that all of the motors we want to be sensored for little to no cost extra, then that would
make it generic for everyone, because if you find a monster sensorless controller, you don't have to use the sensors anyway.

[swbluto]

If you can request that all of the motors we want to be sensored for little to no cost extra, then that would
make it generic for everyone, because if you find a monster sensorless controller, you don't have to use the sensors anyway.

Yep yep. I'd gladly pay more for the option to use hall sensors, if I wished. If I didn't want to use hall sensors, sensorless is pretty straightforward and is a small price to pay for the majority who want sensors.

[salty9]

I guess I could bolt the big copper bus bars to an external heatsink, using insulating pads, but I rather like the idea of internal fan cooling. I think this motor is probably going to need forced air cooling if it's run enclosed/semi enclosed on a bike, anyway. One option might be to build the controller into the motor mounting housing, fit a fan on the end of the motor and have a neat unit that houses the motor, controller and something like one of Matt's reduction drives.

Thanks Jeremy,

You've made me redesign my planned controller for my altermotor.

[RWP]

Thanks guys - this is great!!!

I'm in for 2 if they are sensored, and I can wait although I would love to fondle one of these monsters yesterday

Thanks again,
Roy

[AussieJester]

As i said page back im in for one myself would prefer sensored but am cash strapped due to current spending on RC crusier project by when do we need the $$$ paypaled in please ? I can't get $$$ for ~4 weeks im afraid?!?! Alternatively... if any of your financially wellz off fellas could spring for a spare for me i would reimburse you the cost plus freight and extra 50 bucks for your efforts? Lemme knowz either way please as i would VERY much like one of these for my next custom build...

KiM

[HAL9000v2.0]

Kim, don't worry, I'll save one for you.
I will even make some lightening holes for you

[liveforphysics]

Kim, I'm planning on getting 3-4 of them. I will gladly paypal for 1 extra for you bro.

[AussieJester]

haha cheers Hal and LFP appreciate the offers, ill see when the 'due date' is
for payment if the money is need in a week...well im screwed... so will hit you fellas up,
I guess if your in for 3-4 already Luke and happy to grab an extra i already have your paypal details
and can deposit funds each pay till i have it covered if that's cool? Shall speak with you when i have
all the payment date details anywayz...Thanks again Hal and Luke for your offers

KiM

p.s Hal get back to the workshop i wants updates on that L337 MTB frame damnit!!

[markobetti]

kim dont worry, the date is not like we stated before,since things went in different direction . Hal said it would be the best to make some things differently . So he improved design of the motor in one day.Anyways , the motor will be sensord with Hals cooling system . For everybody sending me pm , please wait a little. The motor will be a state of art, but we need to get new samples and test them.

[AussieJester]

Cheers mate...well i can put money away for it in ~4 weeks so please put me down for a certainty for one sensored motor

KiM

[cell_man]

I'd be interested in 1 or 2 of these motors. Shipping straight to Shanghai. Let us know what's the deal with these and I'll get the funds sorted.

[veloman]

That is an absolute beast. I've love to see a video of someone's complete bike with this on it. Have fun rigging the whole system together to withstand 15hp. And how long will your batteries last?

[amberwolf]

The problem is going to be fitting a large enough gauge extension cord onto the trailer-mounted cable reel.

[tritonwow]

I'm in for two of these motors

[johnws6]

I'll take 1, maybe 2.

[tritonwow]

What's the story morning glory?

Anything new?

[liveforphysics]

I'm putting together some CAD sketches of coupling together 12 of these motors along the belly-pan of a lotus 7 kit to make an EV.

If I can mount the battery similarly low, I could make the lowest center of gravity lotus 7 kit in the world, and perhaps even the best handling lotus 7 in the world. Perhaps 350hp burst, 150hp continous, maybe 1,200-1,500lbs with driver.