As new applications for brushless DC motors become available, the related technologies continue to evolve. The latest applications to take advantage of the benefits of BLDC motors are capacitive-sensing technologies that use capacitive touch switches, like elevator buttons, digital calipers and MP3 players.

About Capacitive Sensing and Commutation Encoders

While capacitive-sensing technologies aren’t necessarily new in the electronics industry, they are new in regards to their use with rotary encoders. In motor-control applications, they measure speed, position, direction and distance.

The benefits of capacitive sensing include:

• Lower costs
• Increased durability
• Low operating currents, including currents in the micro-amp range
• Resistance to airborne contaminants
• Wide temperature range tolerance
• Broad programmability

Hall-effect devices are among the most commonly used to commutate currents in brushless motors. However, instead of using Hall-effect circuitry in brushless DC motors, manufacturers find that commutation encoders with capacitive sensing help ensure long-term nominal accuracy (particularly when there are motors with high pole counts) and more efficient operations. The capacitive switching points are programmable, so alignment and setup is faster.

While optical encoders are more accurate than Hall devices, they cost more to use because the commutation signals come from a pattern etched on a disk, which is only applicable to one motor configuration. If oil from a person’s finger touches the optical disk, data errors could occur. Capacitive technology and the ability program it eliminates such errors and can help save money.

Is your company in need of BLDC motors for sensitive applications? Learn more about Sinotech’s BLDC motor offerings, view our catalog and more.