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

Claim 0:
1. A method for torque control and capacitor voltage balancing of a dual three-level (3L) 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 silicon carbide (SiC) semiconductor switches, comprising:
selecting a first set of voltage vectors, each voltage vector including a set of four possible switching states of the first plurality of SiC semiconductor switches and the second plurality of SiC semiconductor switches;
evaluating a first cost function (J1) for each voltage vector of the first set of voltage vectors to generate a set of first cost functions;
minimizing the set of first cost functions;
identifying a first optimum voltage vector (Vopt-1) from the first set of voltage vectors which minimizes the set of first cost function;
identifying four redundant switching states of the first optimum voltage vector (Vopt) which minimizes the first cost function Jj;
evaluating a second cost function (J2) using the four redundant switching states of the first optimum voltage vector (Vopt-1) which minimizes the first cost function Jj and generating a set of second cost functions;
minimizing the set of second cost functions;
identifying a second optimum voltage vector (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 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 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;
wherein evaluating the first cost function J1 includes:
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 Kψ;
estimating a torque value deviation of the OEIM;
estimating a flux value deviation of the OEIM; and
calculating each first cost function J1 based on:, J
    1
   
   =
   
    
     
      
       ❘
       "\[LeftBracketingBar]"
      
      
       
        T
        ref
       
       -
       
        T
        
         k
         +
         2
        
       
      
      
       ❘
       "\[RightBracketingBar]"
      
     
     
      T
      rated
     
    
    +
    
     
      K
      ψ
     
     ⁢
     
      
       
        ❘
        "\[LeftBracketingBar]"
       
       
        
         
         
          ψ
          s
          ref
         
         
        
        -
        
         
         
          ψ
          s
          
           k
           +
           2
          
         
         
        
       
       
        ❘
        "\[RightBracketingBar]"
       
      
      
       
       
        ψ
        s_rated
       
       
      
     
    
   
  
  ,, for k=1 to 61,
wherein minimizing the set of first cost functions generates a voltage vector which minimizes the torque value deviations and the flux value deviations of the OEIM.