Motor control system with unijunction triggering circuit to compensate for the nonlinearity of an scr amplifier

Abstract

Abstract A MOTOR CONTROL SYSTEM UTILIZING A PHASE CONTROL POWER AMPLIFIER WITH CONTROLLED RECTIFIERS WHICH INCLUDES UNIJUNCTION TRANSISTOR TRIGGERING CIRCUIT MEANS TO VARY THE MAGNITUDE OF ACTUATING SIGNALS TO SAID POWER AMPLIFIER AND COMPENSATE FOR GAIN VARIATION OCCURRING IN THE RECTIFICATION SYSTEM. IN ORDER TO LINEARIZE THE RELATIONSHIP BETWEEN CURRENT IN THE CONTROLLED MOTOR AND INPUT CONTROL SIGNAL APPLIED TO THE MOTOR CONTROL SYSTEM OVER THE RANGE OF OPERATION, A NONLINEAR RELATIONSHIP IS PROVIDED IN THE TRIGGERING CIRCUIT MEANS BETWEEN VARIATION OF THE TRIGGERING PULSE WITH INPUT CONTROL SIGNAL TO COMPENSATE FOR A NONLINEAR RESPONSE BETWEEN VARIATION OF CURRENT WITH FIRING ANGLE IN THE CONTROL RECTIFIER STAGE OF THE POWER AMPLIFIER. A NONLINEAR GAIN IS ACCOMPLISHED IN THE TRIGGERING CIRCUIT BY IMPRESSING A VOLTAGE AT THE EMITTER ELECTRODE OF A UNIJUNCTION TRANSISTOR ELEMENT FROM A CAPACITOR ASSEMBLY BEING CHARGED BY A CONSTANT CURRENT SOURCE SO AS TO PROVIDE DISCRETE SLOPE CHANGES IN THE RELATIONSHIP BETWEEN VOLTAGE ACROSS THE CAPACITOR ELEMENTS AS A FUNCTION OF THE CHARGING TIME. BY UTILIZATION OF A PHASING VOLTAGE IN SAID CIRCUIT, THE TRIGGERING PULSES ARE SYNCHRONIZED FOR OPERATION WITH THE AC POWER SOURCE TO THE CONTROLLED MOTOR. IN A PREFERRED EMBODIMENT, THE TRIGGERING CIRCUIT ALSO INCLUDES MEANS TO VARY THE CHARGING OF THE CAPACITOR ASSEMBLY AS A FUNCTION OF THE MAGNITUDE OF THE BACK EMF IN THE CONTROLLED MOTOR THEREBY PROVIDING IMPROVED LINEARITY OF RESPONSE FOR SPEED CHANGES IN SAID MOTOR.

Inventors

• 👤 William E Egan

Bibliographic Details