An uninterruptible power supply for providing an output power signal to a load comprises a ferroresonant transformer, a resonant capacitor, and an inverter. The resonant capacitor is operatively connected to the ferroresonant transformer. The inverter is operatively connected to the ferroresonant transformer. The inverter is configured to generate the output power signal based on at least one inverter control signal such that the output power signal is a quasi square wave having at least one change of phase and an upper limit. The at least one inverter control signal is held in an OFF state during at least a portion of the at least one change of phase, pulse-width modulated during at least a portion of the at least one change of phase, and held in an ON state when the output power signal is at the upper limit.

A power supply apparatus, including: a transformer including a first primary winding for connection to a first power source and a second primary winding for connection to a second power source, and a secondary winding for delivering power therefrom as the output of the power supply apparatus; a controller for receiving voltage inputs from the first power source and the second power source, and in response to the received voltage inputs control supply from the first power source to the first primary winding and from the second power source to the second primary winding, such that: if the first power source and second power source are available the controller operates to allow power to be supplied to the first primary winding from the first power source and operates to shut off supply of power to the second primary winding from the second power source.

An uninterruptible power supply adapted to be connected between an AC line and a load, comprising a battery system, an inverter, and a transformer, and a controller. The battery system stores battery power. The inverter is operatively connected to the battery system. The transformer is operatively connected to the AC line, the load, and an inverter winding operatively connected to the inverter. The controller controls the inverter to supply power to the primary winding using battery power stored in the battery system based on a cost value indicative of reduction of life of the battery system.

A ferroresonant transformer assembly comprising, a core, a main shunt, first, second, and third windings, first and second tap connectors, and a selection connector. The first windings configured to be operatively connected to a primary power source. The first tap connector operatively connected to a first intermediate point defined by the third windings. The second tap connector operatively connected to a second intermediate point defined by the third windings. The selection connector operatively connected to the at least one load. Based on voltage requirements of the at least one load, the selection connector is operatively selectively connected to a selected tap connector selected from the first and second tap connectors.

An emergency lighting and power system comprises a rechargeable battery, an LED driving circuit, and a charging and discharging control circuit. The emergency lighting and power system is intended to automatically supply illumination or power or both in an event of failure of normal power supply. The LED driving circuit is configured to convert a terminal voltage from the rechargeable battery into an AC voltage to operate a luminaire when a line voltage from AC mains is unavailable. The charging and discharging control circuit comprises at least two relay switches configured to sense a loss of normal power supply, to switch between normal power and an emergency power to operate the luminaire in proper situations, and to meet regulatory requirements without operational ambiguity and safety issues.

A ferroresonant transformer system has a core, a shunt, first and second input windings, an inverter winding, a tank winding, a resonant capacitor, an output capacitor, and a plurality of switches. The tank winding defines a plurality of switch tap locations and at least two output tap locations. The resonant capacitor is connected across at least a portion of the tank winding. Each switch is operatively connectable between one of the switch tap locations and the resonant capacitor. Each output terminal is operatively connected to one of the at least two output tap locations.

A ferroresonant transformer assembly, which is adapted to be connected to a primary power source, an inverter system, a resonant capacitor, and at least one load, comprises a core, a main shunt, and first, second, and third windings. The main shunt is arranged to define a primary side and a secondary side of the ferroresonant transformer. The first windings are arranged on the primary side of the ferroresonant transformer and are configured to be operatively connected to the primary power source. The second windings are arranged on the secondary side of the ferroresonant transformer and are configured to be operatively connected to the inverter system. The third windings arranged on the secondary side of the ferroresonant transformer and are configured to be selectively operatively connected to or disconnected from the resonant capacitor.

A power supply system for generating an output power signal comprises a primary regulation system, a secondary regulation system, and a controller. The primary regulation system comprises a primary transformer and a primary tap switch array configured to regulate a base power signal from the primary transformer such that the output power signal is regulated within a first voltage range. The secondary regulation system comprising a secondary transformer. The controller is configured to apply an adjustment power signal to the secondary transformer to regulate the output power signal within a second voltage range. The second voltage range is smaller than the first voltage range.

A power supply system comprises a primary regulation system, a secondary regulation system, and a controller. The primary regulation system comprises a primary transformer and a primary tap switch array. The secondary regulation system comprising a secondary transformer and an adjustment power signal generator. The controller is configured to control the adjustment power signal generator to apply an adjustment power signal to the secondary transformer. The secondary transformer is configured to combine the adjustment power signal with a base power supply signal from the primary transformer.

Provided is a wind turbine with an auxiliary power supply. The wind turbine includes a generator, a main converter and a transformer. The generator is connected with the main converter. The main converter is connected with the transformer. The transformer is connected with an electrical grid. Thus electrical power with a varying frequency, being produced by the generator, is converted into electrical power with a defined frequency by the main converter and the electrical power with the defined frequency is transformed and provided to the grid by the transformer while the transformation is done in accordance to grid code requirements. An auxiliary power supply, providing auxiliary power, is connected via an auxiliary converter with the transformer, thus the auxiliary power supply is decoupled from the transformer and from the grid by the auxiliary converter.