Thanks to everyone who responded with suggestions. I realize that I made a 'typo' in the olriginal subject line. My ME07009 motor is a brushed DC motor (NOT BLDC). Experiments with the 6 paralleled MOSFETs on a single large aluminum plate running at basically no load, indicates heat dissipation will be significant. Since the MOSFETs are so inexpensive, I will go with 9 of them, each on an individual fan cooled finned heat sink. So 9 @ 80 Amps = 720 Amps- at least triple of max current expectations. One question was asked why build your own controller when there are so many off-the-shelf units. This is my response.
1. It is fun and educational – combines three of my hobbies- sailing, mechanics, & electronics
2. As a back-up propulsion system for an auxiliary diesel sailboat, I see little need for the all functions and programmability of a commercial controller. You need them for a road vehicle.
3. If you shop online, components are very cheap. Components will be probably less than @25.00
4. The main function I need a controller for is ramping up and speed control. An inexpensive ($8.00) low power DC motor controller, including potentiometer, provides the PWM grid voltage to easily drive all the MOSFET grids.
5. Reverse, if needed can be accomplished via a reversing relay.
6. The biggest use for the system will be keeping my 12 volt house battery bank charged as I sail with the prop freewheeling. No need for a controller- simple connection of motor to house battery through a blocking diode works fine. Overcharging is not an issue.
7. If anything goes wrong, I can easily analyze and repair. It so inexpensive I can have lots of spares. Not so with a commercial controller.
I expect to have MOSFET failures as I experiment – but at 60 cents each I can have fun.
Art
Posted by: "A & J Lifshey" <jortlif@msn.com>
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