Driver design cuts acoustic noise from stepper motors

October 23, 2014 // By Graham Prophet
Trinamic Motion Control has disclosed a technology for stepper motors that it calls stealthChop; the new technology significantly reduces the noise of conventional stepper motor operation.

Motors operating at low speed exhibit a phenomenon known as magnetostriction, which causes an audible low frequency 'hum.' Trinamic’s stealthChop minimises magnetostriction by implementing a PWM algorithm that relies predominantly on voltage modulation for motor control at lower speeds. This technology minimises PWM current fluctuation, which is the primary cause of low-speed hum.

“Stepper motors used in automation must respect the needs of their human overlords. The continuous noise of individual stepper motors in a laboratory environment may be rather distracting, and the din from hundreds of stepper motors in an industrial implementation can be deafening,” explained Trinamic R & D Chief Dr. Stephan Kubisch. “Our customers asked Trinamic to perfect a commutation scheme for lower step frequencies that reduces noise. We made it self tuning, easy to use and added an automated switch to transition to higher frequencies.“

Noise limitations are especially desirable in applications that normally occur in close proximity to human operators, in applications where multiple stepper motors are in use, in video surveillance applications where installations near walls and ceilings amplify noise, and in consumer applications, such as home automation and air conditioning, where users expect minimal noise.

Trinamic devices that implement this new stealthChop technology have achieved measured noise levels 10 dB below traditional stepper motor drive ICs.