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Phase Control Regulator with Constant Gain

IP.com Disclosure Number: IPCOM000080793D
Original Publication Date: 1974-Feb-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Johari, GC: AUTHOR

Abstract

A phase-control regulator controls the voltage that is supplied to a load from an alternating voltage source, by turning on a silicon-controlled rectifier (SCR) or analogous device at an appropriate firing angle of the alternating voltage half-cycle. In one known technique, a reference voltage is subtracted from a load voltage signal to form an error signal and the error signal is compared with a linear ramp voltage, to form a firing signal at a time in the supply voltage half-cycle to reduce the error voltage. The gain of these regulators varies with the firing angle and, therefore, the regulation has been undesirably varied.

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Phase Control Regulator with Constant Gain

A phase-control regulator controls the voltage that is supplied to a load from an alternating voltage source, by turning on a silicon-controlled rectifier (SCR) or analogous device at an appropriate firing angle of the alternating voltage half- cycle. In one known technique, a reference voltage is subtracted from a load voltage signal to form an error signal and the error signal is compared with a linear ramp voltage, to form a firing signal at a time in the supply voltage half- cycle to reduce the error voltage. The gain of these regulators varies with the firing angle and, therefore, the regulation has been undesirably varied.

To provide uniform regulation, the timing signal is made nonlinear. In one regulator, a reference voltage is integrated to form the conventional ramp voltage, and the ramp voltage is integrated to form a timing signal that rises in a parabolic shape. This signal is compared with a conventionally formed error voltage signal, to provide a firing angle that gives the circuit a more uniform gain.

In a second regulator, a rectified sine wave is integrated to form an S-shaped signal that is compared with the error signal to form the firing signal. The drawing shows a circuit for forming this signal. A differential amplifier 2 is connected with a capacitor 4 to integrate the sine wave that is applied to its upper input terminal. Amplifiers 5 and 6 turn on a transistor 7 to reset the circuit to begin a n...