On cooling again
First identify what is getting hot – the little $30 infra red thermometers are great for identifying the hot spots in a motor as they can be moved all over the motor and instant readouts obtained
A water cooled motor mount avoids the need for a separate cooler (depending on method used) provides a direct thermal path to the motor can provide a large heat sink mass & simplify the cooling. The way top do it is to cool the mount along the top side by drilling through either front or back or across the bracket.
Alternatively if the motor bearing plate can be removed and direct contact with the stator simply get a new bearing plate made and cool it directly stationary.
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Sent: Friday, 9 September 2011 8:31 PM
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Subject: Re: [Electric Boats] Cooling motors
Sorry, meant to add a link to some photos of the ME0913 motor disassembled to that last post. They aren't the ones I was thinking of, but nevertheless they show that it's just an ordinary axial BLDC arrangement internally: http://www.diyelectriccar.com/forums/showthread.php/ripperton-electric-track-bike-41173p20.html?highlight=ME0913
Also I missed your reference to speed/torque control strategies. I've used battery current control and motor voltage control strategies on my simple BLDC controllers and they both work OK. I'm about to try phase current control to get true torque control (battery current control gives power, rather than torque control, because of the current multiplication effect of the controller). All these control strategies work OK with a plain old ordinary trapezoidal controller and BLDC motor, provided you put the current sensor(s) in the right place and have a fast enough control loop to run the PID throttle control element for current or power control (no PID loop needed for speed control).
There's no need to go to sinusoidal control to get these throttle profiles, plus, depending on the exact topology of the motor you may not want sinusoidal control anyway. The ME0913 is a good example, as the BEMF waveform (derived from spinning the motor mechanically with the windings loaded) is closer to trapezoidal than sinusoidal, indicating that there's little to be gained (other than making the motor run a little quieter) by using the more expensive controller type.
Jeremy
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