How to increase the dynamic torque of the stepper motor?
First,select the stepping motor with small step angle
At low speed,the torque increases as the number of rotor teeth increasing.Select a stepping motor with small step angle to get high torque.In fact HB-type rotor teeth as 50 teeth,permanent magnet magnetic flux leakage will increase,but will not be proportional,this conclusion is effective in 100 teeth.Three-phase HB-type stepper motor from 1.2 degrees (rotor 50 teeth) change 0.6 degrees (rotor 100 teeth),approximately add 1.4 to 1.8 times low speed torque.
Efficiency can improve 2 times.It is easy to buy two-phase unipolar or bipolar stepper motor,but the bipolar drive power tube more than the single-pole type.
Method for stepping motor to increase torque at high speed:
1,reduce the number of turns,so that L reduced
Choose the small inductance L from standard products of motor manufacturers,the rated current will become larger.
2,permanent magnet magnetic flux need small
If the producer can not reduce the permanent magnet,can increase the air gap,so that reduce the back EMF at high speed,increase the current,so that increases torque,make the speed - torque characteristics from low to high speed into a straight line,imporve the torque at high speed,and increase the response frequency.
Third,select the step angle big motor
Stepper motor at high-speed operation,method to improve the torque on drive circuit:
1,Improve the drive current voltage
To maintain high torque at high speed,it is necessary to keep the current constant,and keep chopper to work in constant current state.To make the current constant,only to improve the pulse frequency.When the stepper motor speed at a certain high speed,due to voltage constraints,can only work in constant voltage state;if increase the input voltage,you can make it work in the constant current state at high speed,thereby increase the torque at high speed.
2,Reduce current when the drive circuit cut off
Current in the coil When the power tube is turned off,due to current large change rate,the coil produces a very large induced voltage,
the power tube will have the risk of being punctured,usually there are protection circuit.