Eigo Totoki

Dynamic shaft torque observer structure enabling accurate transient loss measurements

Efficiency and power loss are the necessary metrics for evaluating the performance of electrical drives. These two metrics are calculated based on the measured input and output power of the drive. Input power is calculated from the measured terminal voltages and currents, while output power is calculated by multiplying the measured motor speed with the measured shaft torque. Torque transducers are normally used to measure the windup shaft torque. This method is effective for steady state speed operation. This paper proposes an observer structure that uses standard drive sensors that is capable of estimating the shaft torque during both steady state and transient speed operations, including torque oscillations due to resonance. This enables the motor losses to be measured during transient speed operations (accel./deccl.) which is generally not feasible using torque sensors.

Investigation of different servo motor designs for servo cycle operations and loss minimizing control performance

Servo motors are widely used in many industrial applications. These motors require precise control of acceleration, speed, and position. Different designs can be found in the literature. This paper will compare the response of two common types and will propose a new servo motor design that uses less magnet, lowering the price of the motor. The proposed motor would be able to save energy for the required application (minimize cost industrial process cost) and would be suitable for high-frequency injection based self-sensing techniques.