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AssigneeState of Oregon acting by and through the State Board of Higher Education on behalf of Oregon State University
InventorHian K. Lauw
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A device and associated method to control the electromechanical energy conversion process of a variable speed drive utilizing a doubly fed machine, which provides the mechanical energy as demanded by some mechanical load. Alternatively, a device and associated method is provided for a synchronous motor. The terminals of either the stator or rotor winding of the doubly fed machine are directly connected to a polyphase AC power grid of a certain grid frequency. The device establishes through electronic control a stable operation of the drive at a desired power factor at the terminals of these windings, irrespective of varying load conditions. This capability is provided without the need for computing or sensing this desired power factor and the subsequent feedback of its deviation from the desired value through a properly designed regulator. All signal processing as required can be conveniently and reliably implemented; only the easily accessible quantities of the stator voltage and real power supplied to the motor are sensed and subjected to simple algebraic manipulations. Torque speed characteristics produced by the drive are compatible with any demanded load condition within design limits. These flexibilities are retained along with the capability of electronically adjusting the drive speed without the need for detecting the mechanical load condition.
A method for controlling a doubly fed motor driving a load, the doubly fed motor having stator windings and rotor windings and receiving power from an electric power grid having a system frequency, the method comprising the steps of:
An AC drive system which receives electrical power from an electrical power grid at a system frequency, and which delivers mechanical power to a rotating mechanical load, operating substantially at a desired power factor as seen from the electric power grid, the system comprising:
A method for controlling a synchronous motor under mechanical loads, irrespective of any varying torque or speed requirements of such a load, while maintaining a desired power factor operation, the synchronous motor having DC excitation field windings and receiving power from an electric power grid, the method comprising the steps of:
A method of providing variable speed control to a variable speed drive having an energy converter supplying a doubly fed motor which has stator windings and rotor windings and which receives power from an electrical power grid having a system frequency, the method comprising the steps of:
A variable speed drive controller for controlling a variable speed drive having an energy converter supplying a doubly fed motor which has rotor windings and stator windings, and which receives power from an electric power grid having a system frequency, the controller comprising:
A drive controller for controlling a synchronous speed drive having an energy converter supplying a synchronous motor which has a rotor and which receives power from an electric power grid having a system frequency, the controller comprising:
A power factor synthesizer, for use in a variable speed drive control of a doubly fed motor having excitation windings and receiving power from an electrical power grid having a system frequency, the synthesizer comprising:
A power factor synthesizer for controlling a synchronous speed drive comprising an energy converter and a synchronous motor having excitation windings responsive to the energy converter, the synchronous motor receiving power from an electrical power grid having a system frequency, the synthesizer comprising:
Dependencies are inferred from the claim text.