Brushless Motor Controller

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Fender
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Brushless Motor Controller

Post by Fender » Mon Nov 05, 2018 9:18 am

I am thinking about replacing the motor and controller on my 24v battery electric loco (permanent magnet motor and Curtis controller). The brushless motors (essentially a three phase motor per my understanding) come with their own controller. On the current setup, the motor and Curtis controller are mounted in the loco, but the 5k pot that regulates the speed is on the end of a 15ft signal cable, so I can sit on the rear of the train. In other words, the motor current doesn’t have to flow through the speed control that is on the end of the 15 foot cable. Can I use a similar setup with the brushless motor?
Dan Watson

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Re: Brushless Motor Controller

Post by WJH » Mon Nov 05, 2018 11:17 am

The brushless controller, is it a re-purposed RC controller, or an industrial type? If it's for R/C, you might as well plug it into a R/C receiver and have radio control of your train. If you want to be more old fashioned about it, you can use an arduino that outputs the PWM signal it wants, and plug your potentiometer to an analog input of the arduino, and have it interface the two. Actually would be much simpler to just have it R/C.
If the speed control is an industrial unit, it most certainly has an input for a potentiometer, just make sure it likes 5k pots. All decent speed controls use a low signal voltage to the pots, pots aren't used to directly control the speed, they would burst into flames.

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Fender
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Re: Brushless Motor Controller

Post by Fender » Mon Nov 05, 2018 1:19 pm

I haven't bought a new controller (yet), and don't think the one I have will work with a brushless motor. The motors I'm considering are from electricscooterparts.com. Their web site says the controller is built into the motor. It also says the controller will work with any 5K pot, so this answers part of my question. The other issue is whether the motor is reversible. Apparently some are not, Although I thought any three-phase motor could be reversed by switching two of the leads.
Dan Watson

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Re: Brushless Motor Controller

Post by John Hasler » Mon Nov 05, 2018 1:40 pm

A brushless motor won't work with a controller for a DC motor. Brushless motors can be reversed but a controller built into a brushless motor intended for scooters might have no provision for reversal. Adding reversal to such a motor would be more complex than simply adding a switch to swap two phases. Brushless motors often use more than three phases, and there are sensors involved.

[Edit] I had a look at that site. None of those brushless motors are reversible as shipped. I could probably make one reversible but I'd have to take it apart and hack on it.
Last edited by John Hasler on Mon Nov 05, 2018 2:02 pm, edited 1 time in total.

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Fender
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Re: Brushless Motor Controller

Post by Fender » Mon Nov 05, 2018 1:46 pm

John or WJH,
Do you have a suggestion for a better source than electricscooterparts.com? I’m looking for something in the range of 500-750 watts and 2000-4000 rpm.
Dan Watson

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Re: Brushless Motor Controller

Post by John Hasler » Mon Nov 05, 2018 2:05 pm

Why do you need to replace the motors you have? And why specifically brushless?

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Re: Brushless Motor Controller

Post by WJH » Mon Nov 05, 2018 2:58 pm

I built a speeder from an electric scooter that had one of those brushless motors. The motor with two small sealed lead acid batteries could run around the GGLS track for 4.5 hours(I timed it until my butt couldn't take it anymore).
Brushless motors are efficient, and have lots of torque.
The motor I had also has the built in speed control. It was not reversible without taking it apart, and the other issue is that it might of had an encoder for the speed control which might prevent you from manually reversing it, due to firmware throwing fits.
I'd try a large out runner brushless motor meant for an R/C airplane, with an ESC that has reflashable firmware, so you could put BLHeli software on it. What that enables you to do is have a reverse function within the ESC. The R/C drone racers know about this stuff, but you'd be the first to apply it to a locomotive if I don't do it first. You will also want to gear reduce it so you don't go 40 mph, and you'll also want a soft start which I believe is in the BLHeli firmware, otherwise you will snap your neck back. The BLHeli firmware also allows you to sync multiple ESC'S together to have the same start values from the PWM signal. Those ESC's also have battery saver features set for LIPO batteries which you don't want, again, the BLHeli firmware allows you to fix that as well.
So, a permanent magnet DC motor is a little simpler...

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Fender
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Re: Brushless Motor Controller

Post by Fender » Mon Nov 05, 2018 3:45 pm

I need to replace the current motor b/c the rpm is way too high, and the motor is too small in wattage. I have read about the advantages of brushless motors (high starting torque, efficiency, etc.) and want to consider using one. But, I don’t know much about the electronics. I could go with another permanent magnet motor with better specs if need be.
Dan Watson

John Hasler
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Re: Brushless Motor Controller

Post by John Hasler » Mon Nov 05, 2018 4:00 pm

A DC motor with a tachometer and a good controller that makes use of feedback from the tach can equal the performance of those brushless motors in your application. The only advantage the brushless motors would have for you is less maintenance due to the absence of brushes.

Series traction motors are what are normally used in electric locomotives, but they may be hard to find in the size you need (and decent controllers for them even harder).

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Re: Brushless Motor Controller

Post by WJH » Mon Nov 05, 2018 6:06 pm

Equal the performance for this application. For R/C airplanes, brushless motors equal their IC counterparts, and even exceed them. Thrust to weight ratios that were only a dream two decades ago. But yes, for a slow moving torque hungry locomotive, their advantages aren't really needed. I think I am still going to do it because I can, and why not?

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cbrew
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Re: Brushless Motor Controller

Post by cbrew » Tue Nov 06, 2018 8:24 am

may not be much use on the smaller electric critters, for the large locomotives, this website may be of use http://www.thunderstruck-ev.com/
If it is not live steam. its not worth it.

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Fender
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Re: Brushless Motor Controller

Post by Fender » Sun Mar 10, 2019 3:13 pm

JPEG image 3.jpeg
I want to reboot this thread with a different idea. I found these reversing transmissions that are intended for go-carts, and are relatively inexpensive. If I can connect this to an of-the-shelf brushless motor, then I can use this combo for a powertrain to get what I need. Anyone have experience with them?

$122.99
For TAV2 Series 30 torque converters
5/8" shaft diameter
Reverse Gearbox Transmission for Go-Karts with TAV2 Series 30 Torque Converters.
A reverse gearbox is commonly used on small and medium-size go-karts with 5.5 HP and 6.5 HP engines.
30 Day Warranty

Proposed motor:
24 Volt 600 Watt MAC® Brushless Electric Bicyc
24V 600W 3200 RPM high-torque brushless 24 Volt DC electric bicycle motor. Built-in variable speed controller works with any 5k Ohm throttle or potentiometer to vary the speed of motor from full stop to full forward. Clockwise shaft rotation when facing the shaft end of the motor. 8mm OD D-shaped output shaft (8.6mm across flat spot). Shaft protrudes 1/2" from motor body. 3-bolt 114mm BCD mounting pattern. These are the OEM motors for the ElecTrec® electric bicycle which has a top speed of 18mph and a 20 mile range. Made by MAC®.
Item # MOT-B24600
Dan Watson

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