A standby power supply system is provided for supplying normal AC power to a critical load from an AC power source during normal operating conditions, and for supplying emergency AC power to the load during failure of the AC power source. During normal operation, the standby power supply system actively neutralizes undesirable harmonic components in the input current drawn by the load. The standby power supply system includes a power conversion device having a DC side coupled to a back-up power source and an AC side in parallel with the load and the AC source. A harmonic distortion sensor senses a harmonic distortion current component of a load current drawn by the load during normal operating conditions. A controller is responsive to the harmonic distortion sensor for causing the power conversion device to produce a harmonics neutralizing current to substantially neutralize the harmonic distortion current component produced by the load. A method is also provided for supplying AC power to a load during normal and emergency operating conditions.

Standby power supply with load-current harmonics neutralizer

An embodiment of a power supply includes an input node operable to receive an input voltage, an output node operable to provide a regulated output voltage, an odd number of magnetically coupled phase paths each coupled between the input and output nodes, and a first magnetically uncoupled phase path coupled between the input and output nodes. Such a power supply may improve its efficiency by activating different combinations of the coupled and uncoupled phase paths depending on the load conditions. For example, the power supply may activate only an uncoupled phase path during light-load conditions, may activate only coupled phase paths during moderate-load conditions, and may activate both coupled and uncoupled phase paths during heavy-load conditions and during a step-up load transient.

Power supply with a magnetically uncoupled phase and an odd number of magnetically coupled phases, and control for a power supply with magnetically coupled and magnetically uncoupled phases

An off-line switcher includes an auxiliary winding on the secondary side of the power transformer coupled by a power switch to a secondary voltage source in order to provide uninterruptible power to the output from either a primary AC or a secondary DC source. The power switches coupling both primary and secondary source voltages to the power transformers are driven at identical duty cycles by a common regulation control. Differing transformation ratios between primary and secondary sources of power define different operational ranges and determine flow of power based on the magnitude of the primary source of power.

Off-line switcher with battery reserve

A filter uses a special autotransformer that has a ferromagnetic core with a plurality of legs and flux return bars. A first coil is located on one leg, and a second coil is located on the same leg, but spaced from the first coil. The first coil and at least part of the second coil are connected in series to receive distorted alternating current and at least that part of the second coil is connected to an output terminal. Between the coils and extending at least part of the way from the first leg to an adjacent leg is a magnetic shunt assembly to divert part of the flux generated in the first coil by the alternating current so that that part does not link with the second coil. An air gap is located to link with the second coil to create an inductor in that coil by flux in the second coil, and a capacitor is connected across the second coil to tune it to the fundamental frequency of the alternating current and substantially reduce harmonics in that current.

Harmonic filtering circuit with special transformer

A method for operating a voltage regulator controller, for use in a voltage regulator including coupled inductors, is provided as follows. A first signal is generated for driving a first switch of the voltage regulator. A second signal is generated driving a first switch of the voltage regulator. The voltage regulator determines whether a light-load condition exists. Upon determining the existence of a light-load condition, adjusting the phase difference between said first and second signals so that the first and second signals are approximately in-phase.

Varying operation of a voltage regulator, and components thereof, based upon load conditions

An inductor structure is combined with a ferroresonant regulator as a filter inductor in one instance, and as a regulating inductor in another. In one example, a ferroresonant voltage regulator includes a pair of shunt filters at its output to reduce the low order odd harmonic content of the AC output. The filtering arrangement includes two LC shunt filters having their independent inductor windings wound on a single magnetic core unit. Auxiliary windings coupled to each of the inductor windings are placed in series with the output to buck any remaining harmonics. In a second instance, independent regulating inductors in a multiphase ferroresonant regulator are also realized on a single magnetic structure.

Henry Edward Menkes

Papers

Inductor apparatus for application to ferroresonant regulators