Saietta is a developing electric motor intellectual property for light-weight electric vehicle propulsion. Its ‘S-AC’ motor is a brushless axial-flux AC machine (right), designed for mass manufacture and optimised for vehicles such as scooters, motorbikes, quadbikes and rickshaws, as well as small cars and boats.
The motor architecture is based on the company’s dc axial-flux motor, originally developed by Cedric Lynch – he who invented the >90% efficient brushed ‘pancake’ motor in the 1980s, whose descendants have been the motive force in world record breaking vehicles on land, water and in the air. Lynch is now chief scientist at Saietta.
“The switch from dc motors to ac means we are able to improve efficiency and reduce maintenance requirements because there will be zero brush-wear,” said Saietta engineer Chris Lines.
The company’s applications engineering team uses test rigs, developed with sensor Technology. Torque in the motor’s shaft has to be measured to deduce power, and this is picked up using TorqSense-branded sensors (left) which pick up the tiny distortions from the shaft twisting under load through a radio signal bounced off two piezo electric combs glued at right angles to the shaft.
“The amount of twist in the shaft is proportional to the torque of the moment, so we get a direct reading,” said Lines. “The fact that we do not have to hardwire the transducer to the shaft through slip rings means we can set up a test quickly and reset everything just as quickly. If we had to adjust slip rings every time, our test programme would take far longer to complete.”
Saietta raised £37.5m from an IPO on AIM in July this year. It is aiming primarily at Asia, where governments are mandating electric propulsion to combat chronic pollution, according to Sensor Technology. Its ac motor patent can be viewed here, via Google.
Another application for Sensor Technology’s TorqSense is discussed here.