Control method for electrical converter with LC filter

Abstract

An electrical converter (12) is interconnected via a filter (14) with an electrical load (16) or an electrical power source (20). A method for controlling the converter (12) comprises the steps of: receiving a reference flux (psi *i) for the electrical converter (12); determining output signals (y) comprising currents and / or voltages measured in the filter (14); determining an estimated flux (psi i) from the output signals (y); determining a corrective flux (psi i,damp) from the output signals (y) based on a mathematical model of the filter (14) and a quadratic cost function; determining control input signals (u) for the electrical converter (12) based on a sum of the estimated flux (psi i) and the corrective flux (psi i,damp); controlling the converter (12) with the control input signals (u); and algorithmic filtering of at least one of the output signals (y) by applying a signal filter (32) to the at least one output signal, which is designed for amplifying the at least one output signal at a resonance frequency (40) of the filter (14), whereby the corrective flux (psi i,damp) is determined from the filtered output signals.

Description

technical field [0001] The invention relates to a method for controlling an electrical converter and a converter system. Background technique [0002] Electrical converters, such as active rectifiers and inverters, are used to convert a first electrical current into a second electrical current having a different frequency, eg to power a load, to connect a power supply to a grid or to interconnect two electrical networks. [0003] Specific medium voltage converters are linked with low pass input or output filters which are passively attenuated by large resistors. Typically, the filter includes a filter inductor and a filter capacitor connected in series with a damping resistor. Such filters are called LCR filters. However, such a structure may have considerable power loss in the resistor and may not provide a proper current curve at the output due to the slow decay rate of its damping capability at higher frequencies. [0004] Since the converter needs to have a certain ma...

AI Technical Summary

Problems solved by technology

[0005] From a control point of view, only LC filters may be difficult to ensure the stability of closed-loop systems (converter, attached cables, transformers, motors, etc.)

Due to the resonant peak of the LC filter, higher order resonances in the system may be amplified and the system may oscillate

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