Patent ID: 9065323
Filing Date: 2015-06-23
Classification: H02J,H02M

Abstract:
1. A grid-tie inverter comprising: a power circuit having an input terminal for coupling to a DC power source and an output terminal for coupling to an AC power grid; and a control circuit coupled to the power circuit, the control circuit configured to perturb an AC output current of the power circuit a first time and detect a first change in an AC output voltage of the power circuit without shutting down the power circuit, perturb the AC output current of the power circuit a second time and detect a second change in the AC output voltage of the power circuit, and shut down the power circuit in response to detecting at least the first change in the AC output voltage and the second change in the AC output voltage, wherein the AC output current is perturbed such that the AC output current is decreased and increased in substantially equal magnitudes at least one of the first time and the second time, and wherein the control circuit is further configured to add a current delta after the AC output current is perturbed at least one of the first time and the second time such that the AC output current is decreased and increased in substantially equal magnitudes corresponding to the change in magnitude in the opposite direction when the AC output current is perturbed.