Best Power Technology, Inc.

General Signal Power Systems, Inc.

Mark L Schultz

Kevin R Mengelt

Steven J Paul

Robert Colburn

Murray Leonard

Michael J Cane

An uninterruptible power system having a main power path between input and output terminals monitors the phase of the voltages at the input and output terminals while power is applied to the input terminals from an AC power source. The phase difference between the voltages at the input and output terminals is determined and, upon occurrence of a fault in the power supplied to the input terminals, an inverter is turned on to provide power to the load at a frequency which matches the frequency of the input voltage before the fault and at a phase which is the phase of the voltage at the input terminals before the fault corrected in accordance with the phase difference determined before the fault. Prior to transfer of the supply of power back to the main AC power source when the fault ends, the phase and frequency of the voltage at the input terminals is again measured. The frequency of the voltage from the inverter is adjusted to match that of the voltage at the input terminals, while the phase is adjusted to the phase of the input voltage corrected by a selected phase difference. The selected phase difference may be the last phase difference determined before occurrence of the fault, or a phase difference which is corrected based on the current drawn by the load where the phase shift between the input and output terminals in the uninterruptible power system changes as a function of load current.

Power transfer method and apparatus for uninterruptible power systems

A backup power system has power supply lines extending from input terminals, connectable to a main AC power system, and output terminals, connectable to a load, with a relay connected in a power supply line. The AC input power is monitored and when a fault in the power is detected, the relay is opened and an inverter is simultaneously turned on to provide backup power from a battery to the output terminals at a phase and frequency synchronized with the AC input voltage before the fault occurs. When the AC power system power is restored, the inverter power is again synchronized with the AC input power at the input terminals, the relay switch is closed and the inverter is turned off to allow the main power system to provide power to the load. The inverter may be providing power to the power lines before the relay contacts are opened to minimize the disruption of power supplied to the load during transfers. The switching of the switching devices in the inverter is cut off if the current drawn by the inverter from the battery exceeds a current limit level, but is turned on again after a short period of time less than a cycle of the AC waveform to again attempt to provide power from the inverter to the load. This process may be repeated, if necessary, to provide power to loads which require higher currents during start-up of the load than during normal operation after start-up.

Backup power system and method

An auxiliary power supply system includes an internal combustion engine driving an alternator the output of which is rectified and supplied to DC bus lines across which a storage battery is connected. The DC bus lines may supply a consuming device such as an uninterruptible power supply or telecommunications system. The voltage across the bus lines is sensed and when the voltage drops below a selected value, indicating that the consuming devices is drawing power from the battery beyond a desired limit, the engine is turned on for a period of time to warm it up, during which the power from the generator is not supplied to the DC bus lines. Thereafter, the generator supplies power to the DC bus lines to supply the consuming device and partially recharge the battery until the consuming device is no longer drawing power, after which the engine is shut off. The power supply system includes a controller which monitors the intervals of time between turn-ons of the engine and if a selected period of time is exceeded, the engine is started without supplying power from the generator to the DC bus lines to allow the engine and generator to warm-up, enhancing maintenance of the system. The operating characteristics of the engine and generator are sensed and stored for access by an operator and warnings are provided if these conditions exceed acceptable limits.

Power supply system for a telecommunication system

Auxiliary power supply system for providing DC power on demand

Growing community of inventors

Wisconsin Rapids, WI, United States of America

Mark L Schultz