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Chris, You are correct. The difficult part is that motor efficiency is not a number but rathar a function of speed, torque etc. I normally forgo your calculation and just make torque-rpm meaurements; torque x rpm is potput power.
Joe Grez
President, Electric Paddle
425 241 9241
joe@propelemarine.comOn Aug 14, 2013 3:51 AM, "clh5_98" <clh5_98@yahoo.com> wrote:Hello E-Boaters.
I use ME-0913 motors and Gen4 controllers on my boat. I'm trying to quantify the power output of my system. I work in the electrical field but can't seem to get my head completely around this and come up with numbers that I can hang my hat on. I'm hoping that somebody in this group that really understands the math involved with calculating the power output of these motors can help with this. Based on commonly used formulas for calculating AC motor power output, below is my perception on how this should work. I'm sure there's more to it but I would think this should be pretty close.
(Power In= DC Volts X DC Amps X Controller Efficiency). This should give the power available at the controller output.
(Power Out= AC Motor Volts X AC Motor Amps X Motor Efficiency X Motor Power Factor X 1.732). This should give the power available at the motor shaft.
My thinking is that using these formulas with data collected during test runs that one should be able to establish the equation:
Power In = Power Out
If my thinking is correct, then where I'm going astray is what to use for the controller and motor efficiencies and the motor power factor. Or maybe the AC motor formula that I'm using does not apply to PMAC motors. I appreciate help on this. Sorry to those in this group that might find this topic mundane.
Regards,
Chris
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