CONTROLLING A MODULAR CONVERTER

摘要

A modular converter is disclosed which includes plural converter cells connected in series on a first side, and connected on a second side, wherein each converter cell includes an AC-to-DC converter connected to the first side and a DC-to-DC converter connected to the second side. Exemplary embodiments estimate power transferred by the modular converter; compare the transferred power with a threshold value; when the transferred power exceeds the threshold value, operate in a normal load operation mode; when the transferred power is below the threshold value, operate in a low load operation mode with reduced switching losses.

主权项

1. A method for controlling a modular converter having a plurality of converter cells which are connected in series on a first side and are connected with each other on a second side, wherein each converter cell includes an active front-end AC-to-DC converter connected to the first side and a DC-to-DC converter connected to the second side, the method comprising:
a) estimating power transferred by the modular converter; b) comparing the transferred power with a threshold value; c) when the transferred power exceeds the threshold value, operating the modular converter in a normal load operation mode; and d) when the transferred power is below the threshold value, operating the modular converter in a low load operation mode, in which the converter cells are operated, such that switching losses are reduced with respect to the normal load operation mode; wherein the method includes: e) in the low load operation mode:
(i) a number of DC-to-DC converters of the converter cells are deactivated;(ii) the AC-to-DC converters are run in an intermittent mode; and/or(iii) a minimum number of required converter cells is determined based on the transferred power, with not required converter cells being bypassed by short-circuiting input terminals of the not required converter cells.