METHOD AND CIRCUIT FOR SYNCHRONIZING ELECTRIC SOURCES OF PARALLEL AC ELECTRIC SYSTEMS

Title:

METHOD AND CIRCUIT FOR SYNCHRONIZING ELECTRIC SOURCES OF PARALLEL AC ELECTRIC SYSTEMS

Document Type and Number:

Japanese Patent JPS6447229

Kind Code:

A

Abstract:

PURPOSE: To obtain a method compatible with existing control circuit and employing simple circuitry by detecting the difference of output voltage for both currents and controlling one power supply depending on a frequency control signal and a voltage control signal obtained by demodulating the difference of output voltage. CONSTITUTION: When a first power supply (inverter) 10 having variable frequency and voltage is synchronized with a second power supply 24, output voltages from both power supplies 10, 24 are introduced on lines 34, 36 to a synchronism control circuit 32. The synchronism control circuit 32 produces a voltage difference signal between both voltages and then produces a frequency control signal 54 and a voltage control signal 52 by demodulating the voltage difference signal. Frequency and voltage of the first power supply 10 are then controlled depending on these signals thus synchronizing the first and second power supplies 10, 25. This circuit is compatible with an effective and reactive power control circuit being employed in an existing DC link variable speed constant frequency electric system.

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