Best Power Technology, Inc.

Powerware Corporation

General Signal Power Systems, Inc.

Pensar Corporation

David L Layden

Frederick A Stich

Donald K Zahrte, Sr

Craig Edevold

Cary Frank Winch

Robert F Bourke

Douglas C Folts

Richard V Baxter, Jr

Thomas G Hubert

Michael J Cane

Richard V Baxter

Herbert A Podewils

Robert Bishop

David R Ellingson

Terrance D Paul

Richard I Cook

An electrical cabinet for an uninterruptibe power supply (UPS) system includes universal slots that can receive power modules, battery packs, or chargers. The back plane of the slot has connector terminals for battery packs and power modules. The cabinet can be easily reconfigured as desired by changing the number of power modules chargers or battery packs installed. Circuitry is provided that indicates the capacity and operational readiness of the cabinet. This circuitry monitors the battery packs in each slot, and isolates any detected fault to a particular pack.

System for detecting defective battery packs

An electrical cabinet or chassis for an uninterruptible power system (UPS system) includes universal bays or slots that can receive either power modules or battery backs. The back plane of the slot has separate connector terminals for battery packs and power modules. The slots may also receive battery chargers if so desired. All of the slots of a chassis can be utilized to full capacity before another cabinet needs to be employed. The cabinet is also readily adaptable and can be easily reconfigured as desired without particular concern as to the number of power modules or battery packs that are being used. Sensors are provided which indicate the capacity of the cabinet that has been used (e.g. the number of slots still open and not used by a power module or a battery pack). The sensors also indicate whether a battery pack, power module or other device is inserted into the slot, and whether it is properly inserted, thereby providing an indication of the specifications of the UPS system as presently configured to the user.

Modular method and apparatus for building an uninterruptible power system (UPS)

Presented is a center switching circuit and an inverter and an uninterruptible power supply (UPS) utilizing same. The center switching circuit selectively enables and disables power flow to and from the bus capacitors of an inverter or UPS. As such, the center switching circuitry effectively removes the bus capacitors from the circuit. This allows operation of the inverter or UPS in a high efficiency mode whereby input line voltage may be passed essentially without compensation to the output when the center switching circuit is open. Modulation of the center switching circuit during this mode provides soft charging of the bus capacitors so that they are available to source current in a double-conversion or DC boost mode upon degradation or loss of the line voltage. To supply output power from the bus capacitors, the center switching circuit is closed to associate these capacitors with the neutral. Fault isolation is provided during operation by opening the center switching circuit to prevent power flow from the bus capacitors.

Inverter having center switch and uninterruptible power supply implementing same

Connection of batteries to the DC bus lines across which capacitors are connected in power systems, such as uninterruptible power systems, is carried out using an auxiliary switch which is controlled to connect the batteries to a DC bus line through a precharge resistor momentarily before connection is made through a main connector. The preconnection of the batteries through the precharge resistor provides a controlled rate of charge of the capacitors before closing of the main connector to thereby avoid excessive surge currents. When the main connector is opened, as when the power system is prepared for transportation or long term storage, the auxiliary switch interrupts the current path from the battery through the precharge resistor and provides a current path from the DC bus line through a discharge resistor to ground to bleed down the charge on the capacitors to a desired level within a selected period of time.

Method and apparatus for connection and disconnection of batteries to

An uninterruptible power system has a transformer with a primary connected to input terminals, a secondary connected to output terminals, a static switch connected between the input terminals and the primary, and an auxiliary primary connected to an inverter which is supplied by a battery to provide output voltage to the output terminals when a main AC power system connected to the input terminals has failed. The primary has multiple taps at different voltage levels and a buck-boost winding. The taps of the transformer are switched and the buck-boost winding is controlled to provide either buck, boost, or pass-by to allow control of the output voltage from the transformer to within a few percent of a desired voltage level despite large changes in the input voltage. A battery charger coupled to the auxiliary primary operates as a boost converter to provide current to charge the battery at a current level which tracks the input voltage from the AC power system, thereby providing a substantially unity power factor to the AC power system. The voltage control of the output voltage also controls the voltage at the output of the auxiliary primary to which the battery charger is connected, whereby the voltage applied to the charger is substantially regulated and the output power of the charger itself is substantially regulated. The charger can be operated in programmable modes to provide a desired charge configuration for the battery. Detection of faults in the AC power system is enhanced by accurate detection of the zero crossings of the input voltage from the AC power system, and by comparison of the AC input power waveform with an adaptive reference.

Uninterruptible power system

The inverter of an uninterruptible power system is tested by turning on switches in the inverter at a selected test phase in each half-cycle of the AC input waveform so that the inverter provides a voltage which opposes the AC input voltage waveform during part of each half-cycle of the waveform. The resulting current drawn from the inverter battery, if any, is measured and its peak may be found. The peak battery current during each half-cycle is compared to maximum allowable peak currents to determine if an inverter failure has occurred. If the peak currents are lower than a maximum acceptable value, the test is repeated on a subsequent AC input waveform at a decreased test phase (a shorter time delay from the zero crossing of each half-cycle of the waveform) until the peak current in the first half-cycle is at a selected value, at which time the peak in the second half-cycle is checked to determine if it is within an acceptable range. If not, an inverter test failure is indicated. Inverter test failure is also indicated if repeated cycles during which the test phase is reduced fail to cause the first peak to reach the proper value and the test phase is finally reduced to a minimum allowable test phase. If the inverter has been tested and is found to be operating properly, a battery test can be conducted by selectively disconnecting the AC power system from the load, turning on the inverter for a selected period of time, and detrmining remaining available run time based on the battery voltage while the inverter was running.

Inverter and battery testing for uninterruptible power systems

A power supply for vacuum fluorescent displays has a source of a relatively high frequency signal which is provided to a power driver amplifier which is also supplied with a desired supply voltage. The output of the driver amplifier is a square-wave signal varying between approximately zero and the supply voltage; this signal is provided to the filament of the vacuum fluorescent display such that the filament is heated and is self-biased at a DC level which is substantially one-half the supply voltage level. Self-biasing a capacitor between the filament and ground, which also allows the RMS level of the voltage across the filament to be controlled by controlling the frequency of the output signal from the driver amplifier. The voltage may be regulated by comparing the RMS voltage across the filament with a reference and using the difference to control the frequency of oscillation of the source. A voltage multiplier may be connected to receive the square-wave output from the driver amplifier to produce a higher level DC voltage which can be used to supply the grid and plate drivers with the higher voltage needed for these elements. Two driver amplifiers may be connected together with circuitry to self-oscillate, with the outputs of the two amplifiers being connected across the filament to heat the filament and self-bias the filament at one-half the DC supply voltage level.

Power supply for vacuum fluorescent displays

Two or more gated type power switches, particularly mosfets, are disclosed in a protection circuit which protects the other power switches should one of them short to its respective gate. The circuit includes elements for sensing the occurrence of the failure, for carrying or diverting excess current from the gates, and increasing the impedance of the gates to minimize any damage. The circuit prevents the failure of one mosfet in a drain to gate short mode from destroying or damaging the other parallel mosfets. The invention results in easier analysis and repair of any damage should a breakdown occur, and for the first time makes practical the use of many mosfets in parallel for power switching applications.

Gated parallel power switching devices protection circuit

A method and apparatus are disclosed for use with a battery powered inverter for powering a load through a ferroresonant transformer. The current flow through the inverter-ferroresorant transformer is sensed and is utilized to modulate the inverter's pulse width at a point, after a peak voltage but before saturation begins, when the slope of the inverter-ferroresonant transformer current with respect to time is at or near zero. A maximum current limiting feature can be provided in the method and apparatus of the present invention.

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New Lisbon, WI, United States of America

David L Layden