Efficiency Diagram

The actuator efficiency varies with the operating point as visible in the figure. BLDC motors display a single efficiency maximum. The efficiency at very low torques is poor, because most of the generated mechanical power is used to overcome friction. The efficiency also drops for very high torques, where electrical losses dominate.

The red curve illustrates the actuator efficiency as a function of the generated torque τ. The peak efficiency is indicated by the red circle.

The blue shaded area represents the power that can be delivered to the load as a function of the generated torque τ. The limit is highlighted by the blue solid line. The dashed blue line is the electrical power corresponding to the solid line. The red shaded area describes the power loss.