Liebert Corporation

Paul Taylor

Brian Paul Heber

Terry Dwane Bush

Xian Chen

James K Martin

Peter A Panfil

Mohammad Nanda Marwali

Bret P Fox

Russell E Shelter, Jr

A power supply includes a rectifier that converts an alternating current input voltage to a first direct current voltage. An inverter that converts the first direct current voltage to an alternating current output voltage. A first set of output terminals that receives the alternating current output voltage. A second set of output terminals that receives the first direct current voltage. A charging circuit that charges a backup power source based on the first direct current voltage. The rectifier receives a second direct current voltage from the backup power source based on the power supply operating in a predetermined condition.

AC and DC uninterruptible online power supplies

A power supply includes an isolation transformer. The isolation transformer includes a primary winding and N secondary windings, where N is an integer. The primary winding receives a first alternating current voltage. Each of the N secondary windings generates a second alternating current voltage. M rectifiers convert the second alternating current voltages to a direct current voltage, where M is an integer. X inverters convert the direct current voltage to a third alternating current voltage, where X is an integer. A reference transformer is electrically coupled between the X inverters and output terminals of the power supply, is connected in parallel with the output terminals, and is configured to provide at least one of a neutral reference and a ground reference.

Substation based high voltage uninterruptible power supply

An uninterruptible power supply ('UPS') has a phase-controlled rectifier coupled to a source of AC power and having an output providing a DC bus, the output of the phase-controlled rectifier coupled to an inverter. A first controller generates a firing angle for the rectifier and a fuzzy logic controller generates a firing angle for the rectifier. In an aspect, the rectifier is controlled by the firing angle generated by the first controller during normal operating conditions of the UPS and the rectifier is controlled by the firing angle generated by the fuzzy logic controller during abnormal operating conditions of the UPS. The abnormal operating conditions can include loss of a direct DC bus voltage measurement and or a period of time after the UPS experiences a large load change. In an aspect, the firing angle generated by the first controller is compared to the firing angle generated by the fuzzy logic controller and a rectifier fault condition determined to exist when the two firing angles differ by at least a threshold amount. In an aspect, the first controller is a PI controller.

Intelligent sensorless control of a phase controlled rectifier

An uninterruptible power supply (UPS) system includes a first UPS module that has a first power source, a second power source and a controller operable to selectively connect the first or second power source to a load. A second UPS module is connected in parallel with the first UPS module. The second UPS module also includes a first power source, a second power source and a controller operable to selectively connect the first or second power source to a load. The controller of the first UPS module gradually transfers power from the first power source of the first UPS module to the first power source of the second UPS module to detect the presence of the first power source of the second UPS module.

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Westerville, OH, United States of America

Paul Taylor