I'm new here but I have a few posts on other ebike forums (I guess that's the plural of "forum". Or is is "fori"?)
Here are the two things I'm wondering:
1. Would it be possible to build an inexpensive controller for brushed motors using a little PWM kit, such as the ones available from Jameco, etc, and simply feeding the output of the controller to an array of FETs, for theoretically unlimited current capability? You would basically be using the FETs as amplifiers, stepping up the capability of the little circuit.
2. What is the difference in a controller circuit between hall effect sensing and 0-5k pot sensing of the input signal? Or is there any? So many contollers do both I'm wondering why some work and some don't.
BTW: current projects include the "Huffy-cycle" with a 1000W Unite motor/36V sla (heavy as heck but a fantastic performer!), an E-Zip from Wal Mart which is just for experimentation, and an old Specialized with a Crystalyte Sparrow setup.
1. yes this is possible, however you will have to use slow switch speeds (which increases switching losses) and a lower frequency.
you might be better off replacing the gate driver with a bigger one so you can drive the powerstage directly.
2. hall sensors give a 0-5v signal, which requires different input circuitry to a 0-5k signal.
many controllers have the circuitry for both.
hall sensors last longer and are more reliable, so the industry has been moving towards them for some time.
they also now come in more usable packages.
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km