John in CR
100 TW
speedmd said:Just so I am understanding the two losses correctly, the hysteresis losses are from the irons magnetic pole direction switching in both the stator and rotor core steel and the eddy current losses are those currents induced from magnets passing by the stator's copper coiled steel teeth. Would not these eddy's in turn induce further hysteresis losses on their own and cause somewhat a small curve in the hysteresis loss plot. Thinking this may be small in the normal RPM range, but significant when pushed to high RPM's.
Both hysteresis and eddy currents are caused by the changing magnetic field. Hysteresis is the result of particle movement within the steel as they move to align with the magnetic field. Eddy current losses are the resistance losses from the eddy currents created by the changing magnetic field. To a lesser extent these losses also occur in the permanent magnets. No load current at a given voltage tells us the core losses (and parasitic losses, bearings, windage, etc) in total at that rpm, since the current is low enough that the copper losses are negligible. Give me the the no load current, phase-to-phase resistance, along with Kv, and I have almost everything I need to know. Give me a 2nd no-load current at another rpm, and then the spreadsheet gives us the real good stuff, because it provides enough info the give reasonably accurate slopes of the iron core losses.