Model predictive pulse mode control based on small signal pulse mode optimization

Abstract

A method for controlling an electrical converter system (10) comprises determining a nominal pulse pattern (t * p, i, [Delta] u * p, i) over a future sampling time range and a reference trajectory (x *) of at least one electrical quantity of the electrical converter system (10), where the nominal pulse pattern (t * p, i, [Delta] u * p, i) and the reference trajectory (x *) are determined from an optimized pulse pattern table, the nominal pulse pattern (t * p, i, [Delta] u * p, i) and the reference trajectory (x *) being determined from an optimized pulse pattern table. The reference trajectory (x *, i) comprises a switching transition ([delta] u * p, i) between the output voltages of the electrical converters (12) of the electrical converter system (10), and the reference trajectory (x *) indicates a desired future development of the electrical quantity of the converter system (10); a small signal pulse pattern cost function is determined by minimizing the cost function comprising a small signal error based on the difference between the reference trajectory (x *) and the predicted trajectory (x), where the pulse intensity ([lambda] p, i) of the small signal pulse pattern encodes voltage-time values at each switching transition of the nominal pulse pattern (t * p, i, [delta] u * p, i), where [lambda] p, i, [delta] u * p, i). And wherein the predicted trajectory (x) is determined in range from measured values (i, vc, ig) in the converter system (10) and a model of the converter system (10), into which a sum of the nominal pulse pattern (t * p, i, [delta] u * p, i) and the small signal pulse pattern is input; determining a modified pulse pattern (top, p, i, [delta] up, i) by shifting a switching transition of the nominal pulse pattern (t * p, i, [delta] u * p, i), where the switching transition is shifted by a time interval such that the time interval multiplied by the direction of the switching transition equals a voltage-time value at which the pulse intensity ([lambda] p, i) encodes at the nominal switching transition; and applying a next switching transition of at least the modified pulse pattern (top, p, i, [delta] up, i) to the electrical converter system (10).

Description

technical field [0001] The invention relates to the field of control of electrical converters. In particular, the present invention relates to a method, computer program, computer readable medium and controller for controlling an electrical converter system. Additionally, the invention relates to an electrical converter system. Background technique [0002] Optimized pulse mode (OPP) is particularly suitable for medium voltage converters because of their low total harmonic distortion (THD) at low switching frequencies. To achieve fast closed-loop control and suppress disturbances, model predictive control (MPC) methods are promising in power electronics applications. Specifically, model predictive impulsive mode control (MP 3 C) can be seen as an adaptation of the MPC principle to the OPP control problem. MP 3 C controls the stator flux vector of the motor along its nominal trajectory by manipulating the switching timing of the OPP. For example, EP 2 469 692 A1 describ...

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Problems solved by technology

More specifically, to avoid exciting the filter resonance too strongly, large reference step changes may have to be filtered by the ramp limiter, resulting in a slow step response

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