Utility grid-tied 3-phase central PV inverter embedding neutral point voltage shifting principle into instantaneous current control implementation

This paper concerned with an advanced practical development of utility grid-tied 3 phase voltage source type is instantaneous current controlled inverter with minimized pulse switching number-based pulse modulation strategy. It is a key issue that newly-proposed utility inverter incorporates a new conceptual extended neutral point voltage shifting module into the d-q synchronous rotating cordinate frame-based instantaneous current reference feedback implementation in order to improve system efficiency and achieve high power density. The feasible verifications and practical performance evaluations of 100 kW utility grid-tied 3-phase inverter for central PV power conditioning architecture are demonstrated and discussed on basis of actual system efficiency vs. output power characteristics under the conditions of DC voltage variations, temperature rising performances of three-phase bridge-leg associated power semiconductor devices, together with line current THD, in stead state. In addition to these, output current response in dynamic state when the utility AC voltage is suddenly changed is also illustrated herein. The actual effectiveness of medium/large scale utility grid-tied 3-phase PV inverter with neutral point, voltage shifting pulse modulation is acertained substantially from a practical point of view.