MODULAR HIGH-FREQUENCY CONVERTER AND METHOD FOR OPERATING THE SAME

摘要

A modular high-frequency converter includes submodules, each having an input-side half bridge and a DC link circuit with a DC link capacitance connected in parallel to the half bridge. A DC link circuit voltage drop across the DC link capacitance of each submodule is controlled to a target voltage by adjusting a duty cycle with a closed-loop control structure having a pilot control and a downstream closed-loop error control. Within the framework of the pilot control, a target value for each duty cycle and a target value for the supply current are determined, using a mathematical model of the converter, based on the load-side output currents flowing out of the DC link voltage circuits and on target values of the DC link circuit voltages. Switch position parameters, which map the effect of the switch positions of the input-side half bridges, are each replaced by an associated duty cycle.

主权项

1. A method for operating a modular high-frequency converter having a plurality of submodules with input-side half bridge connected in series via an inductance to a supply circuit supplied by a DC voltage source, with each of the input-side half bridge having a DC link circuit with a DC link circuit capacitance connected across an output of the input-side half bridge, the method comprising:
clocking the associated input-side half bridge with a predetermined duty cycle so as to connect the DC link circuit capacitance of each input-side half bridge to the supply circuit, controlling a DC link circuit voltage drop across the DC link circuit capacitance of each submodule to a predetermined DC link voltage target value by adjusting the predetermined duty cycle with a closed-loop control structure having a pilot control and a closed-loop error control connected downstream of the pilot control, determining, for the pilot control, with a model that approximately mathematically models an interaction of currents and voltages in the supply circuit and currents and voltages in the submodules, a target duty cycle value for the predetermined duty cycle of each submodule and a target current value for a supply current supplied by the supply circuit, based on load-side output currents flowing out from the DC link circuits and based on the predetermined DC link voltage target values, in the model, replacing switch position parameters that map an effect of switch positions of the input-side half bridges based on the determined duty cycle value, and operating the converter with the replaced switch position parameters.