Engelhard Corporation

Engelhard Minerals & Chemicals Corporation

At+t Corp.

Jack J Early

Arthur Kaufman

John Werth

Carl D Keith

John J Mooney

Alfred Stawsky

Kenneth R Burns

An apparatus and a method for using at least two multiphase AC power sources to provide seamless uninterruptible power to a common load by isolating a faulty phase or source upon detection of a fault in one of the sources or in one of the phases thereof. To combine at least two three-phase power sources in parallel, for example, the apparatus includes a power paralleling circuit comprising two three-phase silicon controlled rectifier (SCR) bridges and a controller. Each bridge receives power from one of two separate and/or independent three-phase power sources. The controller monitors the status or condition of respective phases of power and selectively gates an associated SCR in each bridge so as to simultaneously power the common load from the two sources. Isolation switches are located in series with each phase circuit of each power supply. In the event of a fault, e.g., a loss of phase synchronization between corresponding phases of the respective power sources, an over-voltage condition of a phase, an under-voltage condition of a phase, etc., the controller issues gating signals to the appropriate SCR(s) or isolation switch(es) to isolate the defective phase(s) or power source from the load. In an alternative embodiment, an alarm is issued to alert maintenance personnel of a fault condition. A corresponding method for achieving the aforestated fault tolerance is also disclosed.

Redundant multiphase power supplies for common load device

A fuel cell/battery hybrid power system is disclosed which has a microprocessor based control system. The control system enables the fuel cell to be taken out of the system by a switch when its predetermined maximum desired energy output is about to be exceeded by load requirements. The battery is protected from overcharging by a switch which is activated responsive to the sensing of state of charge, load current and fuel cell current.

Fuel cell/battery control system

A method for controlling the air-to-fuel ratio fed to an engine or other combustion device provides for periodically adjusting the air-to-fuel ratio to stoichiometric or near stoichiometric, within the response range of the conventional exhaust gas sensor employed. This establishes a reference point from which the setting of an air-to-fuel ratio proportioning device (e.g., carburetor) is established by moving its adjustment means a selected distance from its setting at the reference point. The selected value may be outside the normal response range of the sensor, either rich or lean of stoichiometric. The apparatus may include a sensor which generates an output signal which is compared against a reference signal by a comparator. When the output signal exceeds (or falls below) the reference signal, a timer to operate the proportioning device adjustment means in the desired direction for a stated interval of time is actuated. A separate timer operates the adjustment means towards stoichiometric at selected intervals to periodically establish the reference point.

Method and means for controlling air-to-fuel ratio

A fuel cell system is comprised of a fuel cell module including sub-stacks of series-connected fuel cells, the sub-stacks being held together in a stacked arrangement with cold plates of a cooling means located between the sub-stacks to function as electrical terminals. The anode and cathode terminals of the sub-stacks are connected in parallel by means of the coolant manifolds which electrically connect selected cold plates. The system may comprise a plurality of the fuel cell modules connected in series. The sub-stacks are designed to provide a voltage output equivalent to the desired voltage demand of a low voltage, high current DC load such as an electrolytic cell to be driven by the fuel cell system. This arrangement in conjunction with switching means can be used to drive a DC electrical load with a total voltage output selected to match that of the load being driven. This arrangement eliminates the need for expensive voltage regulation equipment.

Fuel cell system

An air-to-fuel ratio control mechanism in an internal combustion engine operates in partial response to the output of a control circuit, which circuit in turn is responsive to the output of an oxygen sensor mounted in the exhaust of the engine. The control circuit biases the control mechanism toward a predetermined desired air-to-fuel ratio, normally at or near stoichiometric. When the sensor output deviates above a first predetermined value or below a second predetermined value for longer than a predetermined time period, a comparator circuit provides a disabling signal which disconnects the control circuit from the air-to-fuel ratio control mechanism. At the same time, the disabling signal connects a predetermined signal to the air-to-fuel ratio control mechanism. This predetermined signal simulates a nominal control circuit output to maintain the air-to-fuel ratio close to stoichiometric or some other preferred setting such as a air/fuel ratio which is lean. An indicator is turned on by the disabling signal to alert the operator to possible malfunction.

Growing community of inventors

Perth Amboy, NJ, United States of America

Jack J Early