Design and Fpga Implementation of She Pwm in a Single Phase A.c.chopper Using Generalized Hopfield Neural Network

In this part, a FPGA based implementation of Selective Harmonic Elimination Pulse Width Modulation (SHEPWM) as applied to a single-phase A.C. Chopper using Generalized Hopfield Neural Network (GHNN) is designed and implemented. The objective of this part is to eliminate 5 th , 7 th , 11 th and 13 th order harmonics in the output voltage waveform of the single-phase A.C. Chopper while retaining the fundamental component to the desired value. The switching angles corresponding to the above objective are obtained by solving a set of non-linear algebraic transcendental equations. The problem is reworked as an optimization problem and it is solved by using GHNN. An energy function is formulated for the above problem and a set of differential equations describing the behavior of GHNN are formed by using the derived energy function. The set differential equations describe the behavior of the GHNN form a system of stiff system of differential equations and are solved numerically by any one of the suitable implicit method like semi implicit Runge-Kutta, Rosenbrock method or semi implicit midpoint rule based extrapolation method. In this work, the semi implicit midpoint rule based extrapolation method is used to solve the differential equations. A digital control strategy for implementing the obtained results is also developed and implemented using FPGA-Spartan3-E platform. The VHDL program has been developed to implement the above digital control strategy