20-09-2012, 05:32 PM
SPEED MEASUREMENT OF STEPPER MOTOR
DISAdvantages of stepper motOR
LOW EFFICIENCY
TORQUE DROPS RAPIDLY WITH SPEED
LOW OUTPUT POWER FOR WEIGHT & SIZE
MOTOR GETS HOT IN HIGH SPEED
MOTOR IS NOISY AT MODERATE TO HIGH SPEED
Physical properties of stepper motor
The main components of a stepper motor are the shaft, rotor and stator laminations, magnets, bearings, copper wires and lead wires, washers, and front and end covers.
The shaft of a stepper motor is typically made of stainless steel metal, while the stator and the rotor laminations are comprised of silicon steel.
The bearings of a stepper motor vary with size of the motors.
These magnets are ferrite plastic, ferrite sintered and Nd-Fe-B bonded magnets.
The silicon steel allows for higher electrical resistivity which lowers core loss.
Working of stepper motor
The main use of stepper motors is to control motion, whether it is linear or rotational.
In the case of rotational motion, receiving digital pulses in a correct sequence allows the shaft of a stepper motor to rotate in discrete step increments.
A pulse used in a stepper motor system can be produced by microprocessors, timing logic, a toggle switch or relay closure. A train of digital pulses translates into shaft revolutions.
Each revolution requires a given number of pulses and each pulse equals one rotary increment or step, which is only a portion of one complete rotation.
There are numerous relationships between the motors shaft rotation and input pulses.
Increasing the frequency of the input pulses allows for the speed of the motor shaft rotation to increase
What is stepper motor
A stepper motoris an electromechanical device achieving mechanical movements through conversion of electrical pulses.
Stepper motors are driven by digital pulses rather than by a continuous applied voltage.
Unlike conventional electric motors which rotate continuously, stepper motors rotate or step in fixed angular increments.
One important aspect of stepper motors is the lack of feedback to maintain control of position, which classifies stepper motors as open-loop systems.
A stepper motor is most commonly used for position control.