Automatic V-I crossover regulator

• US 3,986,101 A
• Filed: 03/10/1975
• Issued: 10/12/1976
• Est. Priority Date: 03/10/1975
• Status: Expired due to Term

• Current Assignee: NCR Corporation
• Original Assignee: NCR Corporation
• Inventors: Jensen, Joseph C., Koetsch, Philip W.
• Primary Examiner(s): Goldberg, Gerald
• Application Number:
  US05/556,839
• Time in Patent Office: 582 Days
• Field of Search: 323/4, 323/20, 323/21, 323/22 T, 323/DIG. 1, 307/52, 307/53, 307/58, 307/60, 307/82
• US Class Current: 323/275
• CPC Class Codes: G05F 1/573 with overcurrent detector
• CPC Class Codes: G05F 1/59 including plural semiconductor devices as final control devices for a single load

Abstract

In order to achieve the capability to operate a plurality of identical power supplies in parallel, whereby the drawbacks of the conventional master-slave regulator relationship are avoided, the regulator of each power supply is provided with a load current sensor and a secondary differential amplifier circuit responsive to a predetermined load current for controlling the normal reference voltage supplied to the primary, voltage regulating differential amplifier. As a result of the inevitable, within-tolerance differences in the characteristics of two paralleled regulators, one supply will assume constant current operation at the predetermined load current while the other supply will operate at constant voltage and will carry the remainder of the actual load current. As many identical power supplies as necessary for a given application may be operated in parallel, and a single one will automatically operate in the constant voltage mode while the rest operate in the constant current mode.

Claims

1. A regulated d-c power supply adapted to operate in parallel with one or more additional power supplies schematically identical thereto to provide voltage regulated direct current to a single load comprising:

A. a source of unregulated d-c;

B. regulating transistor means disposed in series between said source and the load;

C. a first differential amplifier having an output terminal coupled to said regulating transistor means for controlling the conduction thereof, said first differential amplifier further including first and second input terminals;

D. means for setting up a first reference potential;

E. means coupling said first reference potential to said first input terminal of said first differential amplifier;

F. voltage sensing means for developing a load voltage signal which constitutes a potential proportional to the voltage applied to the load;

G. means coupling said load voltage signal to said second input terminal of said first differential amplifier;

H. a second differential amplifier having an output terminal and first and second input terminals;

I. means for setting up a second reference potential;

J. current sensing means for developing a load current signal which constitutes a potential proportional to the current provided to the load by said power supply;

K. means coupling said second reference potential to said first input terminal of said second differential amplifier;

L. means coupling said load current signal to said second input terminal of said second differential amplifier; and

M. variable impedance means coupled between said output terminal of said second differential amplifier and said means for setting up a first reference potential for effecting modification to said first reference potential in response to a change in an output signal from said second differential amplifier.

2. The regulated d-c power supply of claim 1 in which said means for setting up a first reference potential includes a first voltage divider of at least two resistance means and in which said variable impedance means comprises a transistor driven by said second differential amplifier and disposed in shunt with at least one of the said resistance means comprising said first voltage divider.

3. The regulated d-c power supply of claim 2 in which said means for setting up a second reference potential includes a second voltage divider by which the load current value causing said second differential amplifier to commence driving said transistor may be adjusted.

4. The regulated d-c power supply of claim 3 in which said second voltage divider comprises a variable resistor.

5. The regulated d-c power supply of claim 4 in which said voltage sensing means includes a variable resistor having a tap connected to said second input terminal of said first differential amplifier whereby the nominal voltage applied to the load by said power supply may be adjusted.