Method and system for detecting a negative sequence for three phase grid-connected inverter systems
AssigneeBallard Power Systems Inc.
InventorsDoug Deng, Kon-King Mike Wang
Life of this patent
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Abstract
A method and system for detecting the negative sequence of three phase grid-connected inverter systems utilizes, for example, computer hardware and/or computer software to remove a direct current component from a direct-axis current feedback for a three phase current of the inverter system to yield a pure alternating current waveform signal. A first low pass filter eliminates high frequency noise from the alternating current waveform signal while passing a negative sequence signal. The filtered signal is rectified to an absolute value, and a second low pass filter flattens the rectified signal to an output signal that is indicative of the magnitude of the negative sequence current.
Claims27
A method for detecting a negative sequence current for a three phase grid-connected inverter system, comprising:
- removing a direct current component from a direct-axis current feedback for a three phase current of the inverter system to yield a pure alternating current waveform signal;
- eliminating high frequency noise from the alternating current waveform signal while passing a negative sequence signal;
- rectifying the signal to an absolute value;
- and
- flattening the rectified signal to an output signal that is indicative of a magnitude of the negative sequence current.
A system for detecting a negative sequence current for a three phase grid-connected inverter system, comprising:
- means for removing a direct current component from a direct-axis current feedback for a three phase current of the inverter system to yield a pure alternating current waveform signal;
- means for eliminating high frequency noise from the alternating current waveform signal while passing a negative sequence signal;
- means for rectifying the filtered signal to an absolute value;
- and
- means for flattening the rectified signal to an output signal indicative of a magnitude of the negative sequence current.
Dependencies are inferred from the claim text.