Xantrex Technology Inc.

Schneider Electric Solar Inverters Usa, Inc.

Renjie Xu

Jun Yin

A photovoltaic inverter for coupling a direct current photovoltaic source to an alternating current energy grid and performing a low voltage ride through. The inverter includes a power bridge to convert direct current voltage to alternating current voltage. A switching crowbar is coupled to the photovoltaic energy source and the power bridge. The crowbar has a switching device having a closed position causing the switching crowbar to dissipate energy from the photovoltaic energy source and an open position to allow direct output from the photovoltaic source to the power bridge. A voltage sensor detects a low voltage condition on the grid. A controller is coupled to the voltage sensor and controls the switching crowbar when a low voltage condition is detected. The switching device is placed in the closed position when the voltage from the photovoltaic energy source is higher than a predetermined threshold voltage and the switching device being placed in the open position when the voltage of the photovoltaic source reaches the voltage when the low voltage condition is detected.

Photovoltaic inverter with control for performing low voltage ride through

A sensor-less technique is described for detecting the status of an AC contactor of a power inverter. In one embodiment, a method is provided of sensing an unexpected condition of an AC contactor used to couple to a power distribution system a power inverter having at least one power conductor. The method includes determining a voltage value for the conductor; determining a current value for the conductor; determining a phase difference using the voltage value and the current value; and monitoring successive values of the phase difference to produce a monitoring result. Depending on the monitoring result, a determination is made whether or not to issue an alert signal. Control routines embodying such technique may be stored on computer-readable media. A power inverter using such technique is described.

Contactor status detection in power inverters

An AC power supply () can be connected in parallel with similar supplies to drive loads (). Each of the AC power supplies () incorporates a discrete controller functioning based on parameters sensed locally and without reference to any of the other supplies.

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Livermore, CA, United States of America

Renjie Xu