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Hendrik Du Toit Mouton

Tobias Geyer

Martinus David Dorfling

Described herein is method for controlling an electrical converter, the electrical converter converting an input voltage (v) into a multi-level output voltage (v), the method incudes: determining an optimized pule pattern (u(x)); and determining switching states from the optimized pulse pattern (u(x)) and applying the switching states to semiconductor switches of the electrical converter, such that the multi-level output voltage (v) is generated, where the optimized pulse pattern (u(x)) includes a plurality of switching transitions (Δu), each switching transition (Δu) encoding a transition between two different levels of the multi-level output voltage (v), at a switching angle (x), where the optimized pulse pattern (u(x)) is determined by optimizing a cost function, where the cost function J(x)=ΔuA(x)Δu is a cost matrix A(x), and where each entry of the cost matrix A(x) depends on polynomials into which the switching angles (x) are input.

Optimizing pulse patterns with Bernoulli polynomials

Disclosed herein is a method for controlling an electrical converter system that includes: determining a nominal pulse pattern (t*, Δu*) and a reference trajectory (x*) of at least one electrical quantity of the electrical converter system over a horizon of future sampling instants, the nominal pulse pattern (t*, Δu*) comprises switching transitions (Δu*) between output voltages of an electrical converter of the electrical converter system and the reference trajectory (x*) indicates a desired future development of an electrical quantity of the converter system; determining a small-signal pulse pattern (ũ(t, λ)) by minimizing a cost function; determining a modified pulse pattern (t, Δu) by moving the switching transitions of the nominal pulse pattern (t*, Δu*) to generate modified switching transitions; and applying at least the next switching transition of the modified pulse pattern (t, Δu) to the electrical converter system.

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Stellenbosch, South Africa

Hendrik Du Toit Mouton