Open source motor controller

Discussion in 'The Projects Forum' started by hspalm, Oct 23, 2010.

  1. hspalm

    Thread Starter Active Member

    Feb 17, 2010
    201
    8
    Hello everyone!
    I have been looking for a high power motor controller to use in my projects. It's not the actual cost of a complete controller that gave me the idea of making my own. All tough the complete controllers don't cost much money, I think many of them are a bit overpriced, and I love the idea of a schematic, PCB layout and the overall design of a circuit being open source. When finished, this project will be available to others as a kit, a design (free, of course), just the PCB or (maybe) pre-assembled.

    I hope you will help me on this one. As the parts that may be sold will probably not even be sold be my, I hope no-one thinks I am using you to earn a profit on this!

    Explaining what I want:
    (Generic) A versatile high power DC motor controller. Power to be controlled by potmeter mounted on either PCB or maybe handlebars of a kick-scooter or similar, connected by wires.
    (Detail) Analog voltage from pot is converted by a uC ADC to a 0-100% PWM which is amplified by mosfets through an h-bridge controller.

    Hopefully I can ask both generic and detailed questions, and anyone is of course welcome to suggest anything for this circuit, even though it may involve a drastic change to the design. Hopefully we will soon be on the track of a very specific design that just needs improvements. The goal is to design an easy-to-understand and as-cheap-as-possible design.

    I have made a sketch that will make the fundamentals of my idea. And here goes my first questions!
    - What could a ~maximum achievable power rating of a product like this be?
    - Is it preferable to use another set of five transistors to fully switch on the h-bridge fets, so I don't have to be limited to the logic level fets?

    I am aware that designs like this is widely available all over the internet, but I also want this to be a sort of learning project for my self!

    Thank you so much, and please comment on anything you want. Both to my intentions of this project, and the design it self.

    A link to the schematic picture, which will soon be scaled down to fit the forum: http://ploader.net/files/60476c03c03566437a4aed01d008dd32.bmp
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    First off, you need at least a high-side driver for the upper MOSFETs. Otherwise, they will get fried in a twinkling. You'd need to be able to raise the gate to 12v+5v, and there is no way the uC will do that by itself.
     
  3. bertus

    Administrator

    Apr 5, 2008
    15,635
    2,342
  4. hspalm

    Thread Starter Active Member

    Feb 17, 2010
    201
    8
    Is there no logic level transistors to use with high enough specs? A high-side driver, that is another transistor to pull the gate voltage higher?

    You really got me thinking here. But I have decided to keep on doing this thing, so I will learn. But thank you for the link!
     
Loading...