One-dimensional modulation common-mode current suppression method for three-phase mid-point clamped three-level inverter

Abstract

The invention discloses a one-dimensional modulation common-mode current suppression technology for a three-phase neutral point-clamped three-level inverter. Three bridge arms of a non-isolated three-phase neutral point-clamped three-level inverter respectively work in three vector states 0, 1 and 2 or the three bridge arms all work in the vector state 1; and the condition that common-mode voltage is constantly equal to 1 / 2 of direct-current bus voltage is ensured, so that the common-mode current in a non-isolated grid-connected photovoltaic power generation system is effectively suppressed. Compared with an existing common-mode current suppression technology, according to the one-dimensional modulation common-mode current suppression technology, no hardware facility is added to the photovoltaic power generation system, so that the cost of the system is reduced; the energy conversion efficiency is improved; the improved one-dimensional modulation strategy is simple in algorithm, high in operation speed and convenient to achieve; and the one-dimensional modulation common-mode current suppression technology conforms to the requirements of renewable energy source and new energy power generation technologies, and is suitable for the non-isolated grid-connected photovoltaic power generation system which does not include a transformer.

Description

technical field [0001] The present invention relates to common-mode current suppression technology in a non-isolated photovoltaic grid-connected power generation system, in particular to a three-phase neutral point clamped (Neutral point clamped—NPC) three-level inverter one-dimensional modulation (1DM) common mode current suppression method. Background technique [0002] The non-isolated photovoltaic grid-connected power generation method without transformers has quickly gained the attention of scientific researchers and industrial circles in various countries due to its absolute advantages of high change efficiency, small size, light weight and low cost, and has been obtained in some European countries. application. However, because there is no transformer as isolation, photovoltaic cells, photovoltaic inverters and the grid form a common-mode loop through the parasitic capacitance of photovoltaic cells to the ground; the common-mode voltage in the common-mode loop is con...

AI Technical Summary

Problems solved by technology

However, in the existing research results of suppressing common mode current, it is very rare to directly clamp the three-level inverter for the three-phase neutral point.

Images