Tiax LLC

U.S. Windpower, Inc.

Certek Ltd.

Community Hydro, LLC

Concord Computing Corporation

Allan Chertok

Per Onnerud

J Thomas Fowler

Jay Jie Shi

Darrell J King

Gerald R Larocque

Lori Barg

John Gjertsen, Sr

Louis Manfredi

Joel Donahue

William Widnall

Thomas J Fowler

A system for generating power from a flow of liquid having at most fifty feet of head and a flow rate of at most 300 cubic feet per second, includes: an axial-flow turbine, a penstock, an intake, a generator, and a control circuit. Each blade of the turbine runner is releasably coupled to the hub and each blade: 1) is configured to extract energy from liquid flowing through the runner by rotating the hub when the flow of liquid contacts the blade, and 2) has a pitch that is adjustable. The length of the penstock is adjustable. The generator is operable to generate electric power from rotation of the turbine. The control circuit to determines changes in the flow of liquid and in response modifies at least one of the following: 1) the speed of the axial-flow turbine's hub, and 2) the flow of liquid that the runner receives.

Power generation systems, and related methods, components and control systems

A simple and robust variable coaxial capacitive sensor and detection method for monitoring the position of a rapidly reciprocating member such as a piston or displacer in a free piston Stirling engine. The coaxial capacitor of the present invention in a preferred embodiment thereof is configured to modulate capacitive electrode area rather than inter-electrode spacing and as a result a highly linear transfer function can be achieved. Also disclosed are detection methods which derive and process signals in connection with applications which have small sensor capacitance variations while suppressing stray capacitance error.

Capacitive position sensor and sensing methodology

A system is provided for balancing state of charge among plural series connected electrical energy storage units that includes a power converter that selectively couples to an individual storage unit of the a string of electrical energy storage units and bidirectionally transfers energy between the individual storage unit and the string of storage units.

Bidirectional power converter for balancing state of charge among series connected electrical energy storage units

A system and method of balancing state of charge among plural series connected electrical energy storage unit is provided. Individual storage units are selectively coupled by semiconductor switches for monitoring and balancing state of charge. When the state of charge of a selected unit is greater than a target state of charge, energy is transferred from the selected unit to the string of storage units, such that the state of charge of the selected unit converges toward the target state of charge. Conversely, when the state of charge of a selected unit is less than a target state of charge, energy is transferred from the string of storage units to the selected unit, such that the state of charge of the selected unit converges toward the target state of charge.

System and method for balancing state of charge among series-connected electrical energy storage units

A control system for a Stirling engine including the use of a synchronous power converter ('SPC') which is connected to the terminals of the alternator in a linear alternator/FPSE power system. According to the teachings of the present invention, the attached SPC is small and portable and further ensures that piston and displacer excursion within the system remain within design limits. The system and method are designed such that it is possible to adjust both the voltage amplitude and the waveform frequency at the terminals of the linear alternator. By controlling these operational aspects, both the speed and the range of travel associated with the piston and the displacer in the FPSE can be controlled.

Free piston stirling engine control

A system and method for determining and balancing state of charge among plural series connected electrical energy storage units is provided. State of change of a selected storage unit in a string of storage units is determined by (i) applying a non-dissipative load to the selected storage unit, resulting in an energy transfer between the selected storage unit and the string of electrical energy storage units through the non-dissipative load and (ii) determining the state of charge of the selected unit from voltage and current data of the selected storage unit resulting from the energy transfer. When the state of charge of the selected unit is different than a target state of charge, energy can be transferred between the selected unit and the string of storage units, such that the state of charge of the selected unit converges toward the target state of charge.

System and method for determining and balancing state of charge among series connected electrical energy storage units

A linear electrical machine may function as an alternator or a motor. Three annular magnets may be provided that move relative to a core. The magnets may all have a different magnetic orientation. Two magnets may have a north pole oriented in a direction parallel to an axis along which the magnets move relative to the core. Another magnet may have a north pole oriented in a direction perpendicular to the axis.

Linear electrical machine for electric power generation or motive drive

A brake (26) employed to control web tension on a roll stand (10) is provided as a generator whose rotor shaft (38) is mounted on the roll stand's core-coupler spindle (16). The rotor (36) may be journaled in the generator's stator assembly (52) so that the spindle (16) supports the entire generator, and alignment problems that might otherwise require complicated flexible couplings, and excessive axial protrusion of the generator into service aisles are avoided. In another version, the generator stator (52) is mounted directly on the roll stand's arm (12) so that generator rotor-stator alignment is set by the journaling of the spindle (16) in the arm (12). Accurate web tension results from current feedback for control of the generator load.

Roll-stand brake

A windpower system includes a support and a turbine having a shaft rotatively mounted to the support. The turbine has variable pitch blades whose pitch is controlled by the differential motion of a rotary control shaft coaxial with the turbine shaft and the turbine shaft itself so that the blade pitch can be varied by a stationary motor without requiring any slip rings or other such wear-prone couplings. In the event of a power failure, rotary motion of the control shaft is prevented so that the turbine blades are feathered solely due to the force developed by the rotating turbine. Also, if the turbine is used to generate electrical power, an induction generator coupled to the turbine shaft is employed whose shaft speed is indicative of generator output power. Accordingly, generator speed is monitored and used to control the pitch of the turbine blades so as to maintain generator output power at the maximum value when wind speed is below the machine's rated wind speed, and no more than rated output power when wind speed exceeds rated wind speed.

Windpower system

In order to control the turbine speed of a windmill employed for power generation, the pitch of the turbine blades is based on a dual-deadband control strategy. If the current turbine speed is determined to be outside of a relatively wide deadband, action is taken to correct the speed by changing blade pitch accordingly. If the current speed is not outside of the relatively wide deadband, then the average of the turbine speed over a recent interval is compared with a relatively narrow deadband within the wider deadband. Action is then taken to change the blade pitch if the average speed is outside the narrow deadband. In this way, wide excursions of turbine speed are corrected promptly, but the frequency of control actions is minimized by requiring only the average speed to be kept within tight limits.

Method and apparatus for controlling windmill blade pitch

Disclosed is a document printer of the type suitable for imprinting messages upon individual documents fed into the apparatus (e.g., bank checks). The apparatus includes an internal printing station disposed along a document feed path. The path includes a feed slot in an exterior wall of the apparatus. The printing station includes both impact printer means and document drive means, the latter operative to move the document along the document path positioning different parts of the document adjacent the impact printer means for the printing of multiple lines of information, where necessary. Both the impact printer means and the document drive means comprise first and second subunits which are positioned, respectively, on opposite sides of a document at the printing station. In particular, the drive means comprise upper and lower rollers, at least one of which is driven, which are engagable with opposite surfaces of the document. The impact printer means comprise an impact print head on one side of the document and a rigid platen on the other side. The platen and the upper driven roller are supported on a first frame above the document path, while the print head and the lower roller are supported on a second frame and positioned to engage the lower surface of a document on the feed path.

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Bedford, MA, United States of America

Allan Chertok