Solving the SHEPWM Nonlinear Equations for Three-Level Voltage Inverter Based on Computed Initial Values

The essentiality and method of establishing the SHEPWM nonlinear equations for phase voltage waveform with quarter-symmetry based on rising-edge and falling-edge for three-level voltage inverter is described. A new effective method for obtaining initial values with very high quality is proposed. One group of initial values thus obtained under an M can always assure the convergence of equations corresponding to majority of M values. The convergent speed of the iteration of the SHEPWM non-linear equations based on the initial values obtained with the proposed method is increased greatly. Solutions of the SHEPWM equations corresponding to M values from 1.15 to 0.01 with a step of 0.01 with fsolve function provided by MATLAB 6.5 are obtained and depicted in curves. The method is experimentally verified through a diode-clamped three-level voltage inverter. Experiment result proved the practicability and validity of SHEPWM Technique for three-level voltage inverter.