Drives and Controls Magazine
Energy harvesting cuts DC motor lengths by more than half
Published:  16 December, 2015

By using an energy-harvesting technology, the German drives manufacturer Wittenstein has been able to develop two series of brushless DC motors with miniature multi-turn encoders that do not need a battery or a gearhead. It says that the motors are less than half the length of comparable machines and 20% smaller in diameter. Eliminating the gearhead and battery from the 32mm and 40mm diameter motors also extends their operating lives.

The cyber dynamic motors exploit the so-called Wiegand effect to produce tiny amounts of energy. As their shafts turn, a Wiegand sensor reacts with the changing magnetic field, generating count pulses and the energy needed to process the signals and store them in non-volatile memory.

The pulses are counted independently of the speed of rotation, generating absolute values, even at low speeds. It is no longer necessary to find a reference position when a motor is started after servicing, a power failure or emergency stop. The drives are said to be more reliable than motors with single-turn or incremental encoders. They can also be positioned more accurately, due to the 16-bit resolution of the multi-turn system.

Wittenstein says that its cyber dynamic motors are much smaller than rival products

The non-contact, wear-free encoders are not affected by shocks, vibration or temperatures up to 125°C.