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Stepping Motor Schedule - Bipolar Hybrid
ModelFrame SizeStep Angle
(degrees)
Phase Voltage
(V)
Phase Current
(A)
Phase Resistance
(Ohms)
Phase Inductance
(mH)
Holding Torque
(mNm)
Rotor Inertia
(kgm2x10-6)
Detent Torque
(mNm)
Weight
(g)
M142618M426141.87.40.32619651.15150
M173118K430171.810.00.330362083.48200
M173118K45.0171.84.30.95112553..48200
M173118K488171.817.00.2881201883.45200
M234118C464231.817.00.3641605005.530360
M237618K48.4231.88.91.1832165044.0591050

A stepper motor uses a permanently magnetised rotor and an stator formed from two electromagnetic coils. The coils can be energized in four configurations. Switching from one configuration to another causes the rotor to "step" and align its magnets with the energized coil. Cycling through the four configurations in a certain order will cause the rotor to steadily move in one direction.

"Hybrid" stepper motor construction combines the two methods of rotor manufacture: variable reluctance and permanent magnet. This combined approach gives a great density of poles than either predecessor, increasing both resolution and torque.


 
 
         

The resolution of a stepper motor can be increased via microstepping. Instead of switching from one position to the next, the voltage applied to the destination coil is gradually increased. This gives smooth motion at the expense of torque. Conversely, a chopper drive will apply a spike of voltage at the start of each step, this reduces the time needed for current to start flowing in the destination coil, allowing the rotor to align in time for the next step even at a high speed under heavy load.

Pull-in torque is the maximum load under which a motor will accelerate from rest to a given speed. Pull-out is the maximum torque that the stepper motor can apply at a given speed. If torque or speed exceeds this curve the motor will lose synchronism and begin to "miss steps".