Patent ID: 11870373
Assignee: KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 9:
10. A non-transitory computer readable medium having instructions stored therein that, when executed by one or more processors, cause the one or more processors to perform a method for torque control and capacitor voltage balancing of a dual three-level T-type multilevel converter connected to an open ends three-phase induction motor (OEIM) having a stator, a rotor, and first, second and third parallel phase paths, each phase path having a first end and a second end, wherein the first end is connected to a first T-type converter including two capacitors and a first plurality of silicon carbide (SiC) semiconductor switches, and the second end is connected to a second T-type converter including two capacitors and a second plurality of SiC semiconductor switches, comprising:
selecting a first set of voltage; each voltage vector including a set of four possible switching states of the first plurality and the second plurality of silicon carbide (SiC) semiconductor switches;
evaluating a first cost function (J1) for each voltage vector of the first set of voltages voltage vectors and generating a set of first cost functions;
minimizing the set of first cost functions;
identifying the voltage a first optimum voltage vector (Vopt-1) from the first set of voltage vectors which minimizes the set of first cost functions;
identifying four redundant switching states of the first optimum voltage vector (Vopt-1);
evaluating a second cost function (J2) using the four redundant switching states of the first optimum voltage vector (Vopt-1) and generating a set of second cost functions;
minimizing the set of second cost functions;
identifying a second optimum voltage vector the switching state (Vopt-2) having optimum switching states of the first plurality of SiC semiconductor switches and the second plurality of SiC semiconductor switches, wherein the second optimum voltage vector which minimizes the second cost function J2;
updating the set of four possible switching states with the optimum switching states of the second optimum voltage vector switching state (Vopt-2) which minimizes the second cost function J2;
generating gating signals for the SiC semiconductor switches using the updated set of four possible switching states;
applying the gating signals to the SiC semiconductor switches to actuate the OEIM and balance the voltages of the capacitors;
performing a two step model predictive control including:
a first step model predictive control process, including:
receiving a rated torque value Trated, a reference torque value, Tref, a rated stator flux value ∥ψs_rated∥, a reference stator flux value ψsref, and a flux weighting factor K104;
receiving, from an encoder, a first torque value T of the rotor and a first flux value ψ of the stator;
estimating a first step torque value deviation of the OEIM;
estimating a flux value deviation of the OEIM;
evaluating the first cost function (J1) based on:, I
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  ,, for each voltage vector of the first set of voltage vectors, where k=1 to 61;
identifying a first optimum voltage vector (Vopt-1) which minimizes the first cost function (J1) based on the voltage Vs across the stator, for each voltage vector;
then performing a second step model predictive control process, including
determining a set of switching states of first optimum voltage vector (Vopt-1);
measuring, with a voltage transducer, a first set of voltages {Vc1, Vc2, Vc3, Vc4} of the capacitors (C1, C2, C3, and C4) of the multilevel converter; and

evaluating the second cost function (J2) based on J2=|vC1k+1−vC2k+1|+|vC3k+1−vC4k+1|for each k for each of the four redundant switching states of (Vopt-1) to generate the set of second functions; and generate the set of second cost functions; and
minimizing the set of second cost functions based on minimizing each second cost function J2 for V2k+1, for each k=1 to 61.