A 6-pulse noncirculating current cycloconverter is used as frequency changer for a high-frequency permanent magnet generator. A high-efficiency, high-speed gas turbine in the power range of 250 kW to 870 kW, drives the generator-converter unit. This system is intended for use in total energy systems or hybrid systems in vehicles and high-speed vessels. The cycloconverter is designed for three-phase 833 Hz to 50 Hz applications. A new vector-control like digital control strategy and a special discrete Fourier filter (DFT), intended for use with a one-phase version of the cycloconverter, are described. Both are implemented in a multi-processor digital controller used for feedback control and pulse-pattern generation. Simulation results and measurements of a laboratory one-phase version of the converter and a dummy-generator, using this digital control strategy and DFT, are given.

A generator-converter unit, consisting of a high speed permanent magnet generator and a high frequency cycloconverter, is developed. The generator-converter unit is intended for use in total energy systems connected to the utility grid, or hybrid systems in vehicles, or vessels. It will be driven by a high speed high efficiency gas turbine. The advantages of this variable speed constant frequency (VSCF) system, such as optimal turbine speed and small size and weight, are discussed. The 6-pulse cycloconverter, used to change the 800 Hz generator frequency to 50 Hz, is described in detail. A new combination of control methods results in a substantial improvement of the power factor load of the generator. Individual pulse control of the cycloconverter by means of digital signal processing results in excellent control properties of the generator-converter unit. Measurements are given on a 50 kW experimental system, consisting of a 600 Hz test generator and a single phase cycloconverter.