Abstract: An apparatus and method for backfeed detection in, and control of, an uninterruptible power system is disclosed. An adaptive controller in an uninterruptible power system enables delivery of power from a second, backup, power source, to loads connected to an output of the system, when a first, primary, input source is detected to be in a fault condition. Subsequent to enabling the second power source, and within a time interval that is less than one AC period following the detection of the input fault, the controller may sense and measure a backfeed of energy from the second source to the first source and may adapt a subsequent fault response based upon the measurement of the backfeed. Adapting the subsequent response may comprise adapting a response to a fault at the output. The subsequent response may comprise disabling or enabling delivery of energy from the second source.

Abstract: Systems and methods for supplying power to a load include a static switch between a primary power source and a power conditioner associated with a secondary power source, and maintenance switches between the primary and secondary power sources and a load. A controller is operable to actuate the switches. The static switch is operable to conduct power from the primary power source to a capacitor associated with the power conditioner. Current supplied from the primary power source includes portions at a fundamental frequency and a harmonic frequency. The secondary power source or the capacitor, or both, can be used to supply reactive power having a current equal and opposite that of the harmonic portion such that substantially all of the current provided to the load by the primary power source is at the fundamental frequency.

Abstract: An apparatus and method for backfeed detection in, and control of, an uninterruptible power system is disclosed. An adaptive controller in an uninterruptible power system enables delivery of power from a second, backup, power source, to loads connected to an output of the system, when a first, primary, input source is detected to be in a fault condition. Subsequent to enabling the second power source, and within a time interval that is less than one AC period following the detection of the input fault, the controller may sense and measure a backfeed of energy from the second source to the first source and may adapt a subsequent fault response based upon the measurement of the backfeed. Adapting the subsequent response may comprise adapting a response to a fault at the output. The subsequent response may comprise disabling or enabling delivery of energy from the second source.