A control system for an AC motor driven cyclic load, such as a beam pumping unit, includes a flywheel, transducer, tachometer, outside set point source, controller, and variable frequency power supply. The flywheel is rotatably connected between the motor and the cyclic load for receiving and storing...http://www.google.com.au/patents/US4971522?utm_source=gb-gplus-sharePatent US4971522 - Control system and method for AC motor driven cyclic load
