** NEW ** STM3 Twin Brushless Motor ESC (Electronic Speed Controller)

Updated December 2018 - Jon Freeman


Using the latest British designed 'ARM Cortex' technology, this board is designed to drive two Brushless (BLDC) Motors in the power range tiny to kilowatt!

STM3 Features

The 'Brushless Brute' locomotive runs on two bogies each of which has two powered axles. One STM3 ESC controller board is fitted to each bogie providing total high efficiency power, current, voltage and speed control - full four quadrant control, bidirectional with Regenerative Braking.

See a video of four STM3 ESC boards driving a selection of motors, rated from 100 to 1900 Watt (looks best at 'Full Screen')

'Brushless Brute' locomotive uses two bogies, each has two brushless motors, powered and controlled by one STM3 ESC module, all four loco axles under fully controlled power. See a short vid of loco in action

Join us for a whole lap around the beautiful track at Bristol Ashton Court


STM3 Twin ESC board - top

How It Works

An ARM Cortex controller is at the heart of the design. This accepts commands from any of the multiple inputs, and using advanced PWM (Pulse Width Modulation) techniques, provides independent control of voltage applied to, and peak current drawn by, each motor. A 'Regenerative Braking' mode enables conversion of mechanical power returning it to the system electrical power supply. This gives full four quadrant control : - Motoring and braking in both forward and reverse.

Massively rated 100V 120A MOSFET modules provide rugged and overload-protected outputs.

Although designed to drive one or two 'Brushless' and other 3-phase AC motors, the STM3 boards can also drive multiple brushed DC motors under full four quadrant control.


STM3 Twin ESC board - bottom

(That's it for the simple description. If you are interested in this board and you are experienced in electronics and engineering, the technical info below should give you all you need to build your own. If not, I have agreed to build a few for club members although I've plenty of other things to be doing, so contact me if you wish.)



Technical Stuff for Engineers

Everything you need to build your own is here.

Two schematic sheets 1 -2

Zip of PCB Gerber files, right click and 'save as' here

Software developed and compiled using ARM Mbed free online toolchain. Published 17th June 2018, Import your own copy from https://os.mbed.com/users/JonFreeman/code/DualBLS2018_06/

Firmware binary file 17 Nov 2018 here

BOM (prices unlikely to be accurate) here

To follow - some useful data sheets

And that's your lot !