Actuator Sizing 1

Losses

• Heat is generally bad for efficiency and system performance

Electric motors

• Heat affects
  • R (increases)
  • Flux (decreases)
  • Torque (decreases)
  • Stored heat (increases)
• High internal heat melts insulation causing short circuit

Motor selection

Datasheet

• Maxon motors
• Continuous = rated
• Same power but different models
  • Different voltage and current
  • Different efficiency
• Nominal voltage -> Nominal power
• No load speed -> speed at internal load / no external load current
• Nominal speed -> speed at rated, continuous, nominal torque / rated power
• Servo motor -> feedback maintains constant speed at variable torque (in the operating region) | increasing voltage gives more power to the motor to maintain speed
• Max continuous torque -> torque at which the motor can theoretically work for ever (only other factors like lifetime ) / $Q_{in}=Q_{out}$
• Operation conditions affects performance and reduce lifetime: cool -> torque 👆 | hot -> torque 👇
• Allow for motor cooling (housing)
• Current protection and temperature protection -> present in motor controller for preventing damage for expensive motor and components (they detect current and time to estimate heat or measure heat directly)
• Expensive drives = protection
• RMS torque should be equal to max continuous torque (don't overestimate) / there is an allowance
• Max efficiency at nominal operating point
• High thermal time constant is good
• High load = isolate motor shaft from load shaft
  
  
• Continuous operation vs. short term operation (thermal time constant)