Browse Prior Art Database

Phase Control of Power Supply

IP.com Disclosure Number: IPCOM000091002D
Original Publication Date: 1969-Sep-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Rooney, JJ: AUTHOR [+2]

Abstract

The three-phase AC to DC power supply at A utilizes phase control to provide precise output voltage regulation. The basic power circuit, comprising silicon-controlled rectifiers D1, D2, and D3, rectifiers D4...D9, controlled rectifier D12, Zener diode D13, unijunction transistor Q7, resistors R12, R13, R14, and capacitor C6, is described in the General Electric SCR Manual, 4th Edition, Pg. 203.

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Phase Control of Power Supply

The three-phase AC to DC power supply at A utilizes phase control to provide precise output voltage regulation. The basic power circuit, comprising silicon-controlled rectifiers D1, D2, and D3, rectifiers D4...D9, controlled rectifier D12, Zener diode D13, unijunction transistor Q7, resistors R12, R13, R14, and capacitor C6, is described in the General Electric SCR Manual, 4th Edition, Pg. 203.

This supply is controlled by a circuit including Zener diode D14, which establishes a reference voltage through the output voltage Eo and R15. A voltage divider of R6, Q4, R1, P1, and R2 operates to adjust the base level of Q2 to approximately 6 volts. Voltage Eo is sampled by R3 and R4 which apply 6 volts to the base of Q1. This is connected with Q2 to provide a differential amplifier. The output of this amplifier is taken across D10 and R7 and is level- shifted up to a higher positive voltage through Q5, R9, R10, and D11. The output of this stage is measured across R10 and D11, and is further amplified by Q6 and R11. Current from the collector of Q6 charges capacitor C6. This is discharged by Q7 to trigger SCR's D1, D2, and D3 as described in the SCR Manual.

Assume that the output voltage Eo attempts to decrease. The base of Q2 does not see a decrease because of Zener diode D14. The base of Q1 decreases since it senses Eo. This causes Q1 to conduct less and Q2 more. The increase in voltage across D10 and R7 causes a corresponding change in v...