Methods for measuring torque ripples in electrical machines

Wireless Torque Pulsations Measurement System for PMSMs

“…demagnetization) in existing machines. Existing torque pulsation measurement systems include: torque transducers based on strain gauges [19]- [23], [25]- [28], Ferraris sensor [19], piezoelectric accelerometers [19], MEMs accelerometers [29], acceleration estimation using rotary encoder [19] and a weight variation of a beam attached to the rotor [24]. Unfortunately, all these methods suffer from some limitations.…”

“…A beam attached to the rotor was proposed in [24] to measure cogging torque; however, its use is limited to zero speed, which is an obvious limitation. Systems based on Ferraris sensors, rotary encoders and piezoelectric accelerometer [19] have been proposed to measure torque ripple from the shaft angular acceleration. Ferraris sensors and piezoelectric accelerometers [19] measures the angular acceleration directly from the rotor shaft, however the attachment to the shaft increases the overall system inertia and requires additional mechanical couplings.…”

“…Systems based on Ferraris sensors, rotary encoders and piezoelectric accelerometer [19] have been proposed to measure torque ripple from the shaft angular acceleration. Ferraris sensors and piezoelectric accelerometers [19] measures the angular acceleration directly from the rotor shaft, however the attachment to the shaft increases the overall system inertia and requires additional mechanical couplings. Rotary encoders obtain the angular acceleration as the second derivative of the measured rotor angle.…”

Wireless Torque Pulsations Measurement System for PMSMs

“…demagnetization) in existing machines. Existing torque pulsation measurement systems include: conventional rotary torque transducers based on strain gauges [20], [22]- [23], Ferraris sensor [19], piezoelectric accelerometers [19], acceleration estimation using rotary encoder [19] and a weight variation of a beam attached to the rotor [21]. However, all existing methods show some limitation.…”

“…A beam attached to the rotor was proposed in [21]; its use being limited to zero speed [21], measuring in the whole speedtorque map not being possible. Systems based on a Ferraris sensor, a rotary encoder system or a piezoelectric accelerometer [19] overcome the bandwidth limitation of rotary torque transducers and can measure torque pulsations with high resolution. However, all these systems present limitations in the low speed range, e.g.…”