V: Volts
I: Current (Amps)
Io: No-load current at a given speed (Amps)
Rm: Motor resistance at a given temperature (Ohms)
Copper loss = I² x Rm
Parasitic losses = V x Io
Total losses = Copper Loss + Parasitic Losses
Watts out = Watts In - Total Losses
Efficiency = Watts Out / Watts In
Parasitic losses:
Bearing losses are proportional to RPM
Hysteresis losses are proportional to RPM
Eddy current losses are proportional to RPM²
Cooling fan losses are proportional to RPM³
Power output:
Maximum (theoretical) power output occurs at half of no-load speed.
Max. power out = V²/4Rm
Current at max. power out = V/2Rm
Maximum continuous power output is dependant on the motor's ability to dissipate heat.
Efficiency:
Maximum efficiency is achieved when Copper loss = Parasitic Losses
Efficiency at maximum power output is 50%
I: Current (Amps)
Io: No-load current at a given speed (Amps)
Rm: Motor resistance at a given temperature (Ohms)
Copper loss = I² x Rm
Parasitic losses = V x Io
Total losses = Copper Loss + Parasitic Losses
Watts out = Watts In - Total Losses
Efficiency = Watts Out / Watts In
Parasitic losses:
Bearing losses are proportional to RPM
Hysteresis losses are proportional to RPM
Eddy current losses are proportional to RPM²
Cooling fan losses are proportional to RPM³
Power output:
Maximum (theoretical) power output occurs at half of no-load speed.
Max. power out = V²/4Rm
Current at max. power out = V/2Rm
Maximum continuous power output is dependant on the motor's ability to dissipate heat.
Efficiency:
Maximum efficiency is achieved when Copper loss = Parasitic Losses
Efficiency at maximum power output is 50%