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Synthesis of load-independent DC drive system

  • US 5,020,125 A
  • Filed: 11/04/1988
  • Issued: 05/28/1991
  • Est. Priority Date: 03/28/1988
  • Status: Expired due to Fees
First Claim
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1. A method for synthesizing load independent direct current drive system comprising:

  • accepting a source of electrical energy of a constant direct current voltage at an input,coupling mechanically a direct current motor shaft to a load to be driven at an output,controlling a power flow from said input to said output,periodically enabling a power semiconductor switch in a power converter for the control of said power flow in a pulse width modulation manner,supplying a resultant control voltage signal for periodically enabling said power semiconductor switch,supplying a position feedback pulse train signal,feeding back the position feedback pulse train and comparing its frequency and phase with frequency and phase of a position command pulse train in a phase frequency detector in a negative feedback manner;

    thereby producing a position error voltage signal proportional to a difference in frequency and phase between the two pulse trains,supplying a velocity feedback voltage signal,feeding back the velocity feedback signal and comparing it with a sum of a velocity command voltage and the position error signal in a summing circuit in a negative feedback manner;

    thereby producing an algebraic sum of the velocity feedback signal and the velocity command and the position error signal,passing a signal obtained as said algebraic sum of three signals through a filtering and stabilizing network;

    thereby producing an error voltage signal proportional to said algebraic sum of the velocity feedback signal and the velocity command and the position error signal,sensing a current through a direct current motor armature,feeding back the sensed current signal through a current feedback circuit of a proportional and derivative function is a positive feedback loop with respect to said error voltage signal and summing the sensed current signal with said error voltage signal,supplying said resultant control voltage signal, obtained as the sum of said error voltage signal and the current signal fed through said current feedback circuit, for periodically enabling said power semiconductor switch to control the flow of power from the input electrical source to the output mechanical load, whereby the direct current motor shaft position and velocity is made independent of said load.

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