Method and system for voltage independent power supply load sharing

摘要

An apparatus and method for load sharing among N current supplies, where N>1. N current supply paths are coupled to corresponding N independent power sources, respectively. A system load is coupled to the outputs of the N current supply paths to receive N current supplies. There is a common current share bus configured to connect to the N current supply paths to provide a common current share signal, used to indicate the current contribution needed from each of the N current supply paths. In this configuration, each of the N current supply paths adjusts an adjustable voltage drop between its power source and the current supply it provides to the system load in accordance with the common current share signal so that the current supplied from each current supply path is consistent with the common current share signal.

主权项

1. A system for two-supply load sharing, comprising:
a first current supply path coupled to a first power source providing a first input voltage, the first current supply path including a first adjustable voltage drop element for producing a first intermediate voltage, and a first current sensing element for sensing a first current flowing through the first current supply path, the first intermediate voltage being produced at a first node between the first adjustable voltage drop element and the first current sensing element; a second current supply path coupled to a second power source providing a second input voltage, the second current supply path including a second adjustable voltage drop element for producing a second intermediate voltage, and a second current sensing element for sensing a second current flowing through the second current supply path, the second intermediate voltage being produced at a second node between the second adjustable voltage drop element and the second current sensing element; a system load coupled to outputs of both the first and second current supply paths to receive first and second supply currents; and a current balancing control element including an error amplifier for comparing the first and second intermediate voltages with each other to produce first and second control signals respectively supplied to the first and second adjustable voltage drop elements to control the first and second adjustable voltage drop elements based on a difference between the first and second intermediate voltages so as to balance the first and second intermediate voltages, wherein the first adjustable voltage drop element comprises: a first device configured to provide a first adjustable voltage drop; a first servo amplifier having a first input coupled to a first input of the error amplifier and the system load, and an output coupled to a control terminal of the first device for adjusting the first adjustable voltage drop; and a first command voltage source taking the first control signal as its input, coupled to the first power source and a second input of the first servo amplifier, the first command voltage source is controlled by the first control signal from the current balancing control element, and the servo amplifier is configured to adjust the first adjustable voltage drop in accordance with a value of the first command voltage source.