Posco Energy Co., Ltd.

Posco Energy., Ltd.

Mitsubishi Electric Corporation

Korea Fuel Cell Co., Ltd.

Ju Young Chang

Jeong Heum Lee

Sang Ho Moon

Jae Sig Kim

Jin Su Lee

An apparatus for protecting a grid-connected inverter from a low grid voltage includes a first output current sensor configured to sense an output current of a grid-connected inverter, a first output current calculator configured to calculate a D-axis current and a Q-axis current of the output current to obtain the output current that is sensed, and a first output current controller configured to determine whether a difference between the output current and a reference current exceeds a predetermined range, and to decrease the output current by a predetermined value when the difference between the output current and the reference current exceeds the predetermined range.

Apparatus and method for protecting grid-connected inverter from occurrence of low grid voltage

An apparatus for controlling overcurrent of a grid-connected inverter due to an abnormal grid voltage includes a grid voltage sensor configured to sense a grid voltage according to an output current of the grid-connected inverter, a voltage variation calculator configured to calculate a D-axis voltage and a Q-axis voltage of the grid voltage to obtain variation values of the D-axis voltage and the Q-axis voltage, and an output current controller configured to determine whether at least one of the D-axis voltage variation value and the Q-axis voltage variation value exceeds a set value of the grid voltage variation, and decrease the output current by a predetermined value when one of the D-axis voltage variation value and the Q-axis voltage variation value exceeds the set value of the grid voltage variation.

Apparatus and method for controlling overcurrent of grid-connected inverter due to abnormal grid voltage

An apparatus and method for compensating for a ripple and offset of an inverter and an apparatus and method for compensating for a ripple and offset of an inverter which removes a ripple component by compensating for an offset component included in a signal input to the inverter from an inverter controller. A method that senses a direct current (DC) input to an inverter from an inverter controller and an alternating current (AC) output from the inverter and removes a ripple component included in the DC based on the sensed currents, a method that removes a ripple component included in a reference voltage that is output from an inverter controller and is input to an inverter, and a method that compensates for an offset component of an AC voltage/AC used for inverter control and reduces a ripple component corresponding to an output frequency of an inverter.

Apparatus for compensating for ripple and offset of inverter and method therefor

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Pohang-si, South Korea

Ju Young Chang