Register To Comment
Page 2 of 2 FirstFirst 12
Results 11 to 19 of 19

Thread: ESCs for 18V 775 Motors

  1. #11
    There are two ways that stall currents are usually handled: Most commonly you just over rate the controller enough to deal with peak currents. This works fine unless things are heavily overvolted or you're using particularly large motors. The other alternative is to use current limiting as you say, where you read off the current and ramp down the input until it comes back down below the limit. Charles Guan has many pages on the development of the Rage Bridge which is definitely worth a read; this uses current limiting so you can get an idea of how it works. For featherweight motors though I'd advise just over rating the controllers enough to handle what you need. A good page to read for that is Chuck McManis' MOSFET rating page , which gives you an idea of what FETs you need. For an 18v 775 you'll probably want a continuous rating of about 60A or near enough.

    As for components, I'd advise using HIP4028 driver chips to drive the MOSFETs; I tried using other things but this is by far the easiest. Few things to watch out for though with the HIP4082; need to run them on at least 10v (I use ~15v), have a PWM frequency of >1kHz, and don't let the high side signals go above about 98% duty cycle else the charge pump will run out of juice. Probably won't make much sense atm but hopefully after doing some research you'll see what I mean :L

  2. #12

  3. #13
    The driver chip needs to be driven by a microcontroller; all it does is interface between the microcontroller and the MOSFETS. The stuff in my previous post is mostly stuff I wish I knew when I started; hopefully should save you from a lot of the mistakes I made during my ESC's development

  4. #14

  5. #15
    Rapidrory, where did you buy your HIP4028's from? Having a hard time tracking them down online.

  6. #16

  7. #17

  8. #18
    That's a high impedance sense line, so no current is going to it (It's the reference voltage for the charge pump). It's isolated up to 80v (Hence the 80v rating) so the controller won't care what sort of currents are flowing through the H bridge as long as the voltage doesn't exceed 80v (which it won't in your application).

    One thing the data sheet doesn't make very clear is that you'll need some ~10 ohm resistors between the driver chip and the MOSFET gates (gate resistors). Keeps the peak drive currents to below what the chip is rated for (1.25A). Also stops resonance in the drive lines and the like but you don't really need to worry about that; just fit some 10 ohm gate resistors and you'll be fine :L

  9. #19

Register To Comment

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •