Abb Research Ltd.

Abb Power Td & Company

Abb Technology Ag

Other

Abb Inc.

Abb T&d Technology Ltd.

Aaron M Jungreis

David L Dickmander

Jeffery Parker

Kyu-Woong Lee

Edward M Petrie

Harold M Stillman

Joseph Oravsky

Vinod Bapat

Jeffrey J Parker

David Slump

John Finney

The invention is directed to a method, system and device for converting direct current (DC) electrical voltage from a fuel cell to an alternating current (AC) voltage. The inventive method regulates power drawn from the fuel cell and from a battery to maintain a substantially constant DC voltage across a DC bus, and inverts the DC voltage from the DC bus to the AC voltage. The method may further electrically isolate the fuel cell from the load. Also, the inventive method may prevent current from flowing to the fuel cell. The inventive method may also provide a charging current to the battery.

Fuel cell inverter

A fuel cell is placed in parallel with a battery via a mechanical switch. The voltage is held nearly constant by the battery and the power flow is controlled by adjusting the fuel cell operating parameters (such as temperature or air flow) and by opening and closing the mechanical switch. The result is a system that operates at nearly constant voltage without the need for an expensive power conditioning system. The output of the system can then be processed via a traditional power conditioning system such as an inverter or dc-to-dc converter without the need for a wide range of input operating voltages. This reduces the cost and size of the fuel cell power conditioning system.

Fuel cell system power control method and system

A system used to protect the occupants of a stationary motor vehicle, particularly unattended children and pets, from dangerous conditions occurring within the vehicle. The system comprises a sensor which senses dangerous environmental conditions such as high temperatures within the vehicle. In the preferred embodiment, the sensor is used with a transmitter to continuously transmit sound detected within the vehicle passenger compartment as well as transmitting information about any dangerous conditions which occur to a remotely located person. In a second embodiment, dangerous conditions trigger an alarm attached to the vehicle. The alarm amplifies the sound detected within the vehicle, such as a crying child, or a barking dog, and also produces a standard alarm sound alternated with an amplified voice declaring the dangerous condition. In a third embodiment, a sensor module attached to a wireless telephone informs a remotely located person of the dangerous condition through another wireless telephone or a pager.

Environmental warning system

Differential measurement of a transformer magnetizing current and a delta-modulation technique is used to provide compensation for dc saturation of the transformer core, with faster response times, low losses, and with immunity to dc drift in the measuring electronics. During the half-cycle in which the output voltage transitions from its positive maximum to its negative maximum, the positive peak value of the magnetizing current is determined, and during the half-cycle in which the output voltage transitions from its negative maximum to its positive maximum, the negative peak value of the magnetizing current is determined. The positive peak magnetizing current value is compared to the similar value from the previous cycle, and the onset of core saturation in the positive direction is then determined. The negative peak magnetizing current value is compared to the similar value from the previous cycle, and the onset of core saturation in the negative direction is then determined. Based on the results of the core saturation determinations, a control action is determined in accordance with a truth table.

Controlling magnetizing current in a transformer by comparing the difference between first and second positive peak values of the magnetizing current with a threshold

Batteries are often used for load-following, particularly in combination with generation sources that cannot respond to fast load changes. Batteries that display &ldquo;memory&rdquo; (i.e., their ability to operate correctly over their entire depth of discharge depends on their previous level of charge or discharge) cannot adequately follow loads. This invention allows the use of batteries that display &ldquo;memory&rdquo; in load-following applications.

Load follower using batteries exhibiting memory

Notching in a switch-mode converter is compensated for to restore a sinusoidal output voltage waveform to the output of the converter, regardless of the load current level, power level, or power factor (both distortion and displacement power factor). Waveform smoothing for a waveform in a switch-mode converter having a DC bus voltage and an output filter inductance comprises determining a ripple current in the converter; determining a time-to-zero; determining a turn-on time; determining the lesser of the time-to-zero and the turn-on time; determining a duty cycle modification based on the lesser of the time-to-zero and the turn-on time; and applying the duty cycle modification to the waveform.

Systems and methods for inverter waveform smoothing

A power conditioner interfaces a load to a fuel cell that produces a low voltage that varies with the load. A dc-to-ac inverter operates with a low voltage input provided by a dc bus . When a positive step load change occurs, a low voltage battery provides power equal to the step change until the fuel cell is able to provide enough power to support the entire load. The power from the battery is supplied to the varying dc bus through a boost converter . When very large positive load step changes occur, the battery can feed power to the dc bus through diode D , rather than through the boost converter. Diode D does not need to be used, but its use allows the boost converter to be sized for common load changes rather than for the maximum possible load change (such as might be seen during a faulted output). A buck converter converts the variable voltage on the dc bus to the appropriate float charging voltage of the battery. The buck converter also supplies power for auxiliary equipment when available from the fuel cell. If the fuel cell is unable to provide the auxiliary power (such as during startup or load transients), then the auxiliary power can come directly from the battery.

High efficiency power conditioner employing low voltage DC bus and buck and boost converters

A power system is provided in which a grid supplies electrical power to a load and in which backup power is provided from one of a generator and a dc storage device. The power system includes a standalone inverter having an input and an output. The output of the standalone inverter is connected to the load. The power system includes a grid parallel inverter having an input and an output. The output of the grid parallel inverter is connected to the grid. A dc bus is electrically connected to the input of the standalone inverter and to the input of the grid parallel inverter.

Energy management uninterruptible power supply system

An electronic circuit, such as a UPS, interfaces a main ac power source and at least one secondary power source to a load. The secondary power source(s) may include one or more auxiliary generators, a flywheel motor generator or microturbine with high speed motor generator, and/or any of a variety of dc storage devices. The electronic circuit includes a dc bus, a first uncontrolled rectifier in combination with a first filter for coupling the main ac power supply to the dc bus, one or more additional uncontrolled rectifier(s) and filter(s) for coupling the auxiliary generator(s) to the dc bus, and a dc-to-ac inverter (between the dc bus and the load) for providing ac output power to the load. The advantages of reduced parts count, increased compatibility between the generator(s) and the electronic circuit, and a simpler method for paralleling many storage and generation devices with a very high power factor to the sources, regardless of the load power factor, are provided.

Uninterruptible power supply

A power supply system for providing long and short term backup power to a load comprises a microturbine system, a flywheel system, and a power electronics module. The microturbine system includes a microturbine attached to a first, high speed motor-generator that includes a first stator, and the flywheel system includes a flywheel attached to a second motor-generator. The microturbine system is started by a direct connection of a high frequency AC voltage output of the flywheel system (in the range of from about 500 Hz to about 2 kHz) to the stator of the first motor-generator. The direct connection of the high frequency AC voltage to the stator involves no intervening electronics.

Flywheel-microturbine system

An electronic interface couples a combination of generation and storage devices with a power grid and/or a load. The interface comprises a DC bus; a DC storage device coupled to the DC bus; a first DC-to-AC inverter (N1) having a DC port operatively coupled to the DC bus, and an AC port; a second DC-to-AC inverter (N2) having a DC port operatively coupled to the DC bus, and an AC port; a switch (S4) for electrically coupling the AC port of the second DC-to-AC inverter to a first generator or an AC storage device; a first rectifier (D1) for coupling an AC output of the first generator to the DC bus; and a second rectifier (D2) for coupling an AC output of the AC storage device to the DC bus. The electronic interface provides an efficient mechanism for integrating a variety of storage and generation devices to produce high quality power and reliability to a load as well as to facilitate interfacing of the storage and generation devices to the power grid for purposes of energy control, load leveling, and peak shaving.

Growing community of inventors

Cary, NC, United States of America

Aaron M Jungreis