Closed Loop Stepper Motor/Servo motor

Like open loop stepper motors, Closed Loop Stepper Motor has many improvements. Firstly the most common design, which incorporates a rotor with permanent magnets and a stationary stator with the windings. Second, the current creates a magnetic field distribution that acts on the rotor to develop torque. Closed Loop Stepper Motor have significantly lower pole counts than normal open loop stepper motor. But they must run in closed-loop type.

Gererally speaking, Closed Loop Stepper Motor are more precise and smart than stepper motors. They run significantly faster than normal open loop stepper motors, with speeds on the order of several thousands of RPMs. This makes Closed Loop Stepper Motor to be able used together with gearboxes to deliver much higher torques at useful speeds. They also deliver more consistent torque across the speed range of the motor. Unlike stepper motors, they do not have holding torque per se.

Closed Loop Stepper Motor system enables the stepper motor driver to command that the load remain at a specific position, however, and the motor will make continual adjustments to hold it there. Thus, Closed Loop Stepper Motor can deliver de facto holding torque. But please take attention that the zero-speed torque scenario depends upon the motor being sized properly to control the load and prevent oscillation about the commanded location.

With closed-loop feedback, Closed Loop Stepper Motor deliver high accuracy positioning coupled with better speed and acceleration than normal open loop stepper motor. The trade-off is increased cost, size, and complexity.

Closed Loop Stepper Motor typically use rare-earth magnets while stepper motors more frequently use less expensive conventional magnets. Rare-earth magnets enable the development of higher torque in a smaller package. Closed Loop Stepper Motor also get a torque advantage from its overall physical size. Closed Loop Stepper Motor diameter uaually range from NEMA 17 all the way up to 220 mm. Due to these combined factors, Closed Loop Stepper Motor can deliver torques of up to 250 foot-pounds.

The combination of speed and torque enables Closed Loop Stepper Motor to deliver better acceleration than stepper motors. They also deliver improved positioning accuracy as a result of closed-loop operation.