I have problem in speed control of DC shunt motor chopper circuit. My motor is working fine when i connect it in open loop configuration by varying the armature voltage (armature voltage is varied by varying duty cycle) but when i connect the motor in closed loop system, the speed of motor suddenly increases automatically (armature voltage increases from 0-120V automatically ) and my chopper circuit gets bypassed and motors starts to operate in free running mode. i am attaching my circuit with this post. Can anyone please suggest me the way out for my problem...
There may be a problem with SG3524 error amplifier input voltage range. You can try to divide the error amplifier output down to the allowed voltage range.
Hello,
Thanks for your suggestion but i have one more query.
V to F converter (lm331) generates output in the range ( 0 to 0.6V ), when motor will run from low to high speed. 0 to 0.6V range is set by preset R9. If will reduce voltage range from (0 to 0.6V) to (0 to 0.1V) then it will work as open loop (without feedback circuit) circuit.