Model predictive pulse pattern control based on optimizing a sequence of averaged switch positions

A computer for controlling an electrical converter system, the computer comprising at least one processor, the at least one processor programmed to:

• determine a switching signal and a reference trajectory of at least one electrical quantity of the electrical converter system over a horizon of future sampling instants, wherein the switching signal and the reference trajectory are determined from a table of optimized pulse patterns, and wherein the switching signal comprises switching transitions between output levels of an electrical converter of the electrical converter system and the reference trajectory indicates a desired future trajectory of the at least one electrical quantity of the converter system;
• generate a sequence of averaged switch positions from the switching signal over the horizon, wherein the switching signal is divided into sampling intervals, wherein the sequence of averaged switch positions comprises an averaged switch position per sampling interval, and wherein the averaged switch position is determined by averaging the switching signal defined by the switching instants and output levels in the sampling interval;
• determine a sequence of optimized averaged switch positions by optimizing a cost function based on the sequence of averaged switch positions, wherein the cost function comprises an error term with a difference of the reference trajectory and a predicted trajectory, wherein the cost function additionally comprises a term with a difference of the averaged switch positions and the optimized averaged switch positions, and wherein the predicted trajectory is determined over the horizon from a model of the converter system, into which a sequence of modified averaged switch positions and measurements of the converter system are input;
• determine an optimized switching signal for a current sampling interval by moving switching transitions in the switching signal, such that in the current sampling interval the average of the switching signal with the modified switching transitions equals the optimized averaged switch position;
• and
• apply at least the next switching transition of the optimized switching signal for the current sampling interval to the electrical converter system.

A controller for an electrical converter system, the controller programmed to:

• determine a switching signal and a reference trajectory of at least one electrical quantity of an electrical converter system over a horizon of future sampling instants, wherein the switching signal and the reference trajectory are determined from a table of optimized pulse patterns, and wherein the switching signal comprises switching transitions between output levels of an electrical converter of the electrical converter system and the reference trajectory indicates a desired future trajectory of the at least one electrical quantity of the converter system;
• generate a sequence of averaged switch positions from the switching signal over the horizon, wherein the switching signal is divided into sampling intervals, wherein the sequence of averaged switch positions comprises an averaged switch position per sampling interval, and wherein the averaged switch position is determined by averaging the switching signal defined by the switching instants and output levels in the sampling interval;
• determine a sequence of optimized averaged switch positions by optimizing a cost function based on the sequence of averaged switch positions, wherein the cost function comprises an error term with a difference of the reference trajectory and a predicted trajectory, wherein the cost function additionally comprises a term with a difference of the averaged switch positions and the optimized averaged switch positions, and wherein the predicted trajectory is determined over the horizon from a model of the converter system, into which a sequence of modified averaged switch positions and measurements of the converter system are input;
• determine an optimized switching signal for a current sampling interval by moving switching transitions in the switching signal, such that in the current sampling interval the average of the switching signal with the modified switching transitions equals the optimized averaged switch position;
• and
• apply at least the next switching transition of the optimized switching signal for the current sampling interval to the electrical converter system.