Patent ID: 9172296
Filing Date: 2015-10-27
Classification: H02M,Y02E

Abstract:
1. A photovoltaic system comprising: a photovoltaic array; a distribution system, wherein the distribution system distributes power away from the photovoltaic array; N inverters coupled to the distribution system, each of the N inverters is configured to convert DC power from the photovoltaic array to AC power and apply the AC power to the distribution system; N attenuating components, each of the N attenuating components is coupled to a corresponding one of the N inverters, and each of the N attenuating components is disposed to attenuate common-mode high frequency voltages derived from each of a corresponding one of the N inverters, and each of the N attenuating components is disposed in series with a current loop to block common-mode currents in the current loop that includes a corresponding one of the N inverters, the photovoltaic array, ground, and the distribution system, thereby enabling each of the N inverters to be coupled to the distribution system without an isolation transformer, wherein a portion of the current loop between the photovoltaic array and ground is a capacitance of the photovoltaic array to ground, wherein the frequency of the high frequency voltages is a function of the switching of the N inverters; and N damping components disposed in parallel to the capacitance of the photovoltaic array to ground and sized to damp the common-mode currents which are potentially excited by the common-mode high frequency voltages derived from the N inverters and to prevent instability due to the attenuating components and the capacitance of the photovoltaic array to ground, each of the N damping components is coupled to a corresponding one of the N inverters, wherein N is greater than one.