Vedders ESC, high torque BLDC traction motors, and overhead traction in large scale model railways

With the help of Rory from the Minimal Gauge Railways group on Facebook, and Jeramiah from Ollin Board Company, I've come across a scheme I wish to use for high torque brushless DC traction motors for my heavy haul 7.25" gauge large scale model trains. The loco will, pursuant to my article in Issue 30 of Miniature Railways Magazine, be based on the example of the Wootton Light Railway, based in the Isle of Wight. The trams on the Wootton system have 48VDC worth of deep cycle SLA batteries on board, hooked up to the overhead at 48VDC, and to the motors at two sets of 24VDC (effectively doubling the current). Power to the overheads is supplied by a cheap Chinese manufactured stick welder, and is good for a section of 100 metres (quoted is 100 yards, but that's pretty close to 100 metres by new money). Cross section of overhead is 1.9mm^2 according to Howard of Wootton fame, he says it "gets a little warm." However, he can easily obtain the cabling by stripping surplus 10A mains cable, and it is easy, and cheap to replace. Corrosion is fought by using a V section in the sprung trolley pole that uses friction to clean the corrosion off the overhead contact wire.

So I'm presuming Howard uses standard PMDC motors, as his railway is quite a bit older than the current crop of reasonably priced equipment. I intend on having a ZG100 Bo-Bo loco with 24VDC 500W PMDC motors for shunting, a number of ZG150 Bo-Bo-Bo locos with 2,000W derated BLDC motors, and the grandfathers of them all, the ZG200s with Bo-Bo-Bo-Bo trucks, and a thumping 10 horsepower. Lady Iona, my speeder I'm using to enter Chris Stockdales competiton on the Minimal Gauge Railways group on Facebook, will use two 12VDC 250W BLDC motors, and a single 12VDC SLA battery, to keep costs down. I'll be talking some more with Jeramiah about the batteries used in long boards (see further down for some details).

ZG100 loco

ZG150-1500 loco

ZG200 loco

Or at least, that's a general idea. Cabs will more look like this:

Of course, now you can see why I'm wanting a Tesla Powerwall killer, and now you can guess what voltage it'll run at - 48VDC. Of course, the onboard storage of the locos themselves is a Powerwall killer on its own, my "1500" series will indeed be Li-Ion battery locos, with benefit of overheads.

Anyway, here's Benjamin Vedders ESC, which according to Rory, and confirmed by Jeramiah to have what you would call "low end power" in the internal combustion engine world - a high torque output.

http://vedder.se/2015/01/vesc-open-source-esc/

I personally think Benjamin has come up with a decent open source controller here, full of features, good embedded chip, Linux based configuration program, ability to slave multiple controllers over CAN bus, and ability to use an I2C based Wii Nunchuk controller to provide input. Of course, the VESCs are more designed for the long board world, and a one inch thick, 10kg long board full of 18650 cells has reported to get 80km range. That's not bad, considering my Mum got 165km of range out of her electric car, with a bootful of LiFePO4 batteries, and a 22kW motor. I need a couple of hundred metres, potentially up to a kilometre in later stages, up a reasonable slope (anything near a 1 in 40) hauling a couple of tonnes. My application is wildly different to a long board, but in some ways, it's kind of similar too, in terms of needing torque.

These are the BLDC traction motors I plan to get, that were recommended to me by Jeramiah:

http://www.hobbyking.com/hobbyking/store/__18129__Turnigy_Aerodrive_SK3_6374_192kv_Brushless_Outrunner_Motor.html

They'd have to be derated from the near on 2.7kW output, down to 2kW output peak, using the Ollin heatsinked VESCs, with blowers on the traction motors and traction packs (VESCs). I had quoted my normal maximum would be near 1.8kW per motor/ traction pack, but once underway, and not going up a slope the current draw would be minimal from the inertia.

That's an Ollin VESC, in all its glory. Quite a nice bit of kit, US$135 will call one of these puppies your own, and international postage (for us Aussies, and my UK friends) is US$40. You'll want something running Linux to get the VESC configured. I plan on using a Raspberry Pi as a go to. Then again, I was thinking of using the Sinclair Poco Open Source version on the trains as a computer, so it's all good. Arduino to run the control system (ie, throttle and reverser), running over I2C to the master board, then CAN bus to connect the slaves. A quick change of parameters on a loco can MU the locos, just make sure there is a common electrical connection at 24VDC from chassis to chassis so there is no ground loops between VESCs. Perhaps a jumper in an MU cable can set that parameter?

That's a controller I have seen on Minimal Gauge, using a cheap Chinese reversing switch off eBay and a potentiometer under the throttle. Of course, the high currents in my locos won't be at the reversing switch, rather, it's at the traction packs. A simple +5VDC TTL signal will go through the reverser, same with the throttle, it's output is analog.