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Low-voltage piezo motor challenges mini DC motors

01 May, 2002

Low-voltage piezo motor challenges mini DC motors

Small DC motors are being challenged by a miniature piezoelectric motor said to have many advantages over electromagnetic machines. The Elliptec motors, developed by a Siemens spin-off, are said to be smaller, more powerful, simpler, quieter, easier to control, and potentially cheaper, than conventional DC motors.

Although piezoelectric motors are not new, previous designs have required precision construction and high operating voltages, making them expensive. The new motor (above) operates from a 3-6V DC supply, has a simpler construction with just three moving parts, does not require critical tolerances, and is substantially cheaper.

A piezoelectric element generates vibrations at up to 100kHz that move a rod or spin a wheel. According to Elliptec, the motor weighs one twelfth as much as an equivalent electromagnetic motor, and is one fifth of the size. It does not need a gearbox – its speed is controlled electronically, using a third as many electronic components as a conventional mini DC motor controller. Elliptec claims that the motion control is comparable to that of more expensive stepper motors.

The basic motor produces linear motion at speeds up to 30cm/s and forces of up to 1N, or higher if several motors are used together. To achieve rotational movement, the motor produces linear motion at the rim of a wheel, with the rpm value and torque governed by the wheel`s diameter.

Initially, the motor will have a similar price to conventional DC motors. Applications are expected to include toys, air-conditioning vents and computer components. The motors are likely to be particularly attractive where space is limited, where noise is a problem, or where slow or well-controlled motion is needed.

Dr Bjoern Magnussen, Elliptec`s chief executive, predicts that there will also be applications in industrial automation, cars and homes. "What is particularly exciting are the new applications now becoming possible with the motor," he says. "In many cases, the motor can be used where previously it was not possible to use a motor.

"As production volumes increase over the next few years, we expect prices to drop significantly and go below the one dollar level," he adds.

The motor was originally developed in 2000 by Siemens` Corporate Technology organisation in Munich. Elliptec was formed as an independent company last year, with backing from Siemens. The technology was shown publicly for the first time at a toy fair earlier this year and, according to Magnussen, the company has already won a substantial number of orders.

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