Abstract: A high efficiency static voltage clamped parallel resonant converter for converting power between two AC and/or DC circuits includes a link circuit between an input switch circuit and an output switch circuit. The link circuit comprises a parallel resonant circuit and link switch elements which are switched to generate a unipolar train of link voltage pulses. All of the switches are "soft-switched" on and off at substantially zero voltage or zero current. Each link voltage pulse consists of a zero segment and a non-zero segment. The duty cycle of these voltage pulses is controllable by the link switches and such that the duration of the zero and non-zero segments are independently controllable. Pulse width modulation (PWM) and pulse area modulation (PAM) can be applied for reduced filtering requirements and maintaining high efficiency for operation at fractional load conditions. The link voltage is clamped to a maximum voltage during the non-zero segment of each link voltage pulse.

Abstract: A high efficiency static series resonant converter and method for converting power between two electric AC and/or DC circuits includes a resonant tank coupled to a link current synthesizer for generating a train of unipolar link current pulses with controllable duration zero and nonzero current segments. A blocking switch deactivates oscillation of the resonant tank in initiating each link current pulse, which is subsequently clamped by a buffer inductor. Each pulse is terminated by natural commutation through resonant oscillation. The pulses are substantially squarewave and have a high duty cycle leading to minimal peak current values. Minimal switching losses are incurred by switching at substantially zero voltage and zero current.

Abstract: An apparatus and method is disclosed for an improved control system for a series resonant converter for transferring power between a source and a load. The control system comprises a series resonant circuit including a capacitor and an inductor with a first and second switching matrix connecting the series resonant circuit to the source and the load, respectively. A controller selects a combination of switches for transferring power between the source and the load using a single segment half-cycle resonant waveform that produces a final voltage on the capacitor within a preselected boundary.

Abstract: An AC variable speed drive (VSD) system having a brushless doubly-fed motor receives power from an electric power grid at a system frequency of the grid and drives a mechanical load. The motor has a rotor with rotor windings and a stator with stator windings comprising first and second polyphase stator systems. The first stator system receives power from the grid at the system frequency. A sensor senses a parameter of the received power by the drive and produces a corresponding power sensor signal. A VSD controller receives and processes the power sensor signal and a reference signal which has been established according to a desired motor operation strategy, and generates therefrom a controller signal. A converter, such as a power electronic converter, receives and converts power from a converter powThis invention was made with government support under Grant No. 79-85BP24332, awarded by the Bonneville Power Administration. The United States government has certain rights in this invention.

Abstract: An energy conversion generation system receives energy from a resource and converts the energy into electrical power for supply to a polyphase electric power grid operating at a system frequency. A prime mover driven by the resource energy and a converter, such as a power electronic converter, for produces excitation power from power received from a converter power source. A brushless doubly-fed generator has a rotor with rotor windings and a stator with stator windings comprising first and second polyphase stator systems. The rotor is driven by the prime mover. The first stator system supplies the electrical power to the grid, and the second stator system receives the excitation power from the converter. A sensor senses a parameter of the electrical power output supplied to the grid and produces a sensor signal corresponding to the sensed parameter. A controller controls the converter in response to the sensor signal. The controller establiThis invention was made with government support under Grant No.

Abstract: An apparatus and method is disclosed for an improved AC--AC series-resonant converters incorporating power pulse modulation with internal frequencies of tens of kHz is applied to a series-resonant converter system for generating synthesized multiphase bipolar waveforms with reversible power flow and low distortion. The high pulse frequency allows the application of the principle of modulation and demodulation for fast system response. Switches are required which have bidirectional current conduction and voltage blocking ability. The conventional series-resonant AC--AC converter applies a total of 24 anti-parallel thyristors. The circuit configuration of the present invention is a series-resonant AC--AC converter with only 12 thyristors. Use of the converter results in a higher efficiency and lower costs.

Abstract: Disclosed is a device and method to control the conversion of an arbitrary resource energy into mechanical energy and subsequently into electric energy with a variable-speed generation system utilizing a turbine and a doubly-fed generator, to be connected directly to a power grid of a certain grid frequency. Via electronic control of the rotor speed by controlling the rotor winding excitation frequency, the device has the capability of providing an optimum tradeoff in maximum turbine efficiency and minimal generator losses to secure maximum efficiency of the total conversion process, irrespective of varying resource and electric load conditions. The excitation requirements of the generator are confined to moderate levels and yet a wide rotor-speed variation margin, starting from zero speed, is permitted.

Abstract: 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.