Help with DIY Brushed DC Motor Build

Hi all,

I’m studying electrical engineering at university and I’m working on putting together an electric bike for my senior project . I have an old brushed DC hub motor and three new rechargeable 12V lead-acid batteries that have a capacity of 15Ah each. I also have a bike frame that fits my hub motor and an ebike throttle I inherited from one of my dad’s old projects. I’ve looked extensively but I can’t find any specs on my motor online.

The thing I’m struggling with is I have no idea how to build a control unit between the batteries and the motor. I think a buck converter whose output voltage is somehow regulated by the position of the throttle might work but I have a strong feeling that there’s more to it than that.

Does anyone know of any resources detailing the typical circuitry between batteries and a brushed DC hub motor in the context of electric bikes?

Any and all replies are appreciated!

-Sean

You're looking for a Brushed Motor Controller. There's a lot of circuit diagrams out there on the internet,
https://www.google.com/search?q=brushed+motor+controller+schematic&ie=utf-8&oe=utf-8

If you're willing to pay the access fee, there's a GREAT tech section at the 4QD company site, which not only includes schematics for some of their advanced controllers, but also reasoning on why they did various design choices, and tutorials on exactly how these things work.


There's also probably some schematics/etc here on ES.

If you look up Jeremy Harris' threads here on ES, he was working with the MC3303x chips designing a brushless controller, but AFAICR the chip itself can also be used as a brushed controller, so you could adapt his design for that.

Numberonebikeslover here on ES also designed and built his own brushed controller from scratch, so you can look thru his threads and see if he posted the schematic/etc there for it.

I'm sure there's others.


Or you could just buy a cheap brushed controller at one of the electric scooter parts websites, then reverse-engineer that to understand how it works, and build your own from there.