SYSTEM AND METHOD FOR LOW SPEED CONTROL OF POLYPHASE AC MACHINE

摘要

A power converter configured to improve power capture in a wind turbine during low wind speed operation is disclosed. The power converter converts the power generated by the alternator of the wind turbine into a suitable AC current for delivery to a utility grid or to an electric load independent of the utility grid. The power converter is configured to operate in multiple operating modes, utilizing both synchronous and non-synchronous control methods, to extend the operating range of the power converter. During non-synchronous operation, the power converter utilizes a modulation routine that may either vary the dead-time compensation period during a constant modulation period or vary the modulation period with a constant on-time. A seamless transfer between non-synchronous and synchronous control methods with low total harmonic distortion (THD) improves the range of power generation for wind generators.