Closed loop digital system for controlling the speed of electric motors

摘要

Of the type having a phase generator to deliver the excitation signal to a chopper circuit that chops the excitation signal under the influence of a control circuit 4 that includes an up/down counter 6 connected to a down counter 7 controlled by an oscillator 8 so that it delivers the chopped signal to some switches 3 to regulate the time of application of the voltage to the various windings of the motor 5. The control circuit 4 has a multiply/divide circuit 9 that is connected to the input of the down counter 10 of the up/down counter 6 so that the input of the up counter 11 of the up/down counter 6 receives pulses of a determined frequency FO for the purpose of accurately controlling the slip of the motor and the response time of the control system 4. The multiply/divide circuit 9 receives pulses at its three inputs at a frequency proportional to the speed of the motor Ftaco and the desired speed of the motor Fteo and a fixed reference frequency Frefl and generates frequency control pulses at its output equal to Ftaco x Frefl/Fteo. <IMAGE>