Abstract:
A three-phase grid-connected inverter, a control system thereof and a control method therefor. The inverter is a three-phase three-leg grid-connected inverter, and a filter capacitor is connected to a negative electrode of a DC input bus to form a filter loop, so as to filter harmonic wave in the circuit, realizing high-quality grid-connected current at small power, without increasing an inductance value, so that the parallel inverter device in the system operates stably and thus is applicable to photovoltaic microinverters. Moreover, the three-phase three-leg grid-connected inverter operates in a discontinuous conduction mode, that is, in a switching cycle, the inductive current is reduced to 0, so that the switching loss of the three-phase three-leg grid-connected inverter is reduced.
Abstract:
The invention provides a solar photovoltaic three-phase micro-inverter system comprising a plurality of three-phase micro-inverters. Every three of the three-phase micro-inverters form a group and are coupled to a three-phase AC power grid. Each of the three-phase micro-inverters comprises 3 single-phase inverter circuits, each of the single-phase inverter circuits comprises 2 conversion circuits, and each of the conversion circuits corresponds to one phase of the three-phase AC power grid. AC outputs of the same conversion circuits of the three micro-inverters in one group are coupled to three-phase live wires of the three-phase AC power grid respectively. Accordingly, the invention provides a method for improving conversion efficiency of the solar photovoltaic three-phase micro-inverter system.
Abstract:
This invention provides a solar photovoltaic system, comprising: a plurality of photovoltaic assemblies, for harvesting solar energy to generate DC currents; a plurality of micro-optimizers having input terminals coupled to the photovoltaic assemblies and having output terminals connected in series with each other, for optimizing output currents and/or output voltages of the photovoltaic assemblies, to generate maximum power; a manager configured to communicate with the plurality of micro-optimizers, for managing operating states of the micro-optimizers; and an inverter coupled to one or more strings of the micro-optimizers, for converting the optimized DC currents into AC currents and outputting the AC currents to a power grid. This invention further provides a method for energy harvest optimization and a method for fault detection of a solar photovoltaic system.
Abstract:
The invention provides a solar photovoltaic three-phase micro-inverter, comprising DC terminals, connected with three DC photovoltaic assemblies for receiving DC; three single-phase inverter circuits, having DC input terminals connected with the DC photovoltaic assemblies via the terminals, for converting the DC to AC; AC terminals, connected with the AC output terminals of the inverter circuits and a three-phase AC power grid, for outputting the AC generated by the inverter circuits; wherein DC input terminals of each inverter circuit are connected in parallel with each other, and AC output terminals are connected with one phase of the three-phase AC power grid and a neutral wire via the AC terminals. The invention further provides a solar photovoltaic generation system. The invention connects DC sides of three single-phase inverter circuits in parallel, which can simply eliminate ripple power at DC side input terminals in a three-phase micro-inverter.
Abstract:
A three-phase grid-connected inverter, and a method and a device for controlling the three-phase grid-connected inverter are provided. The method is applied to a three-phase three-leg grid-connected inverter. A structure of the three-phase three-leg grid-connected inverter is improved, so that a filter capacitor (C1, C2, and C3) is connected to a negative electrode of a direct current input bus to form a harmonic bypass circuit. Inverter devices connected in parallel in the system operate stably without increase of inductance of an inductor (L1, L2, L3). In addition, the three-phase three-leg grid-connected inverter according to the present disclosure operates in a discontinuous mode of inductor current (iL1, iL2, and iL3). That is, in the process that a power switch transistor (Q1, Q2, Q3, Q4, Q5 and Q6) on bridge legs is turned on, the inductor current (iL1, iL2, and iL3) drops to zero.
Abstract:
The invention provides a solar photovoltaic three-phase micro-inverter system comprising a plurality of three-phase micro-inverters. Every three of the three-phase micro-inverters form a group and are coupled to a three-phase AC power grid. Each of the three-phase micro-inverters comprises 3 single-phase inverter circuits, each of the single-phase inverter circuits comprises 2 conversion circuits, and each of the conversion circuits corresponds to one phase of the three-phase AC power grid. AC outputs of the same conversion circuits of the three micro-inverters in one group are coupled to three-phase live wires of the three-phase AC power grid respectively. Accordingly, the invention provides a method for improving conversion efficiency of the solar photovoltaic three-phase micro-inverter system.