US 4,618,779 A · System for parallel power supplies

Abstract

A system and method of connecting power supplies in parallel that provides desired voltage regulation at the load and current sharing between the power supplies. The power supplies are connected in parallel at the load. Each power supply also has a sense line connected at the load. Each power supply includes means for measuring the current delivered to the load. Each supply also includes an electronically controlled variable resistive element in its respective sense line. The amount of current being supplied by each power supply to the load is measured. A controller determines if an unacceptable imbalanced current condition exists, i.e., it determines which power supply is supplying too much or too little current and the controller selectively changes the value of the appropriate variable resistive element in the sense line of that power supply in order to change the current being delivered to the load in a direction that corrects for the imbalanced condition. All such corrections are controlled so that a desired voltage regulation is maintained at the load.

Claims12

Dependent claims

A system for connecting a plurality of power supplies in parallel, each of said power supplies having an output terminal for connecting a power line between the output terminal and a common load, and a sense terminal for connecting a sense line between the sense terminal and the common load, each of said power supplies having control means therewithin for adjusting the power delivered to said common load over said power line in response to a sense signal appearing at said sense terminal, said system comprising:

means for sensing the current delivered to the load through the power line of each of said power supplies;
means for comparing the current sensed by said sensing means against a desired shared current value, and for generating a control signal representative of said comparison;
and
means responsive to said control signal for varying said sense signal appearing at the same terminal of each of said power supplies in a manner that causes the current delivered by that power supply to the load to approach said desired current value, wherein said means for varying the sense signal appearing at the sense terminal comprises a variable impedance element inserted into the sense line of each power supply, said variable impedance element having an impedance that varies as a function of a signal applied to a control terminal thereof, said control signal generated by said comparison means being coupled to the control terminal of said variable impedance element.

1 more element

An apparatus for connecting a plurality of power supplies in parallel such that each power supply provides a portion of the power delivered to a common load, comprising:

connecting means for connecting a power output terminal of each power supply to said load;
current measuring means for measuring the current flow in each of said connecting means;
voltage sensing means for sensing the voltage developed at said load, said voltage sensing means including a voltge sense line connected between said load and each of said power supplies;
a variable impedance element inserted into said voltage sense line, said variable impedance element having an impedance value associated therewith that varies as a function of a control signal applied thereto;
and
a control element coupled to said voltage sensing means, said control element being configured to generate the control signal that is applied to said variable impedance element, said control signal having a value associated therewith that is a function of the measured current flowing to said load, and said control signal having a value that maintains the impedance of said variable impedance element within a desired range.

3 more elements

Dependencies are inferred from the claim text.

System for parallel power supplies

Life of this patent

System for parallel power supplies

Life of this patent

Abstract

Claims12