Improvement of stability in current-programmed SEPIC DC/DC converters

Techniques to enhance the stability of current-programmed single-ended primary inductance converters (SEPICs) are described, ranging from component selection to sensing a filtered copy of the control current. A summary is presented of a method for analyzing stability by direct calculation of the eigenvalues of an averaged time-evolution operator. The key to the method is the expression of duty ratio variation as a function of the state variables, i.e. voltages and currents in the circuit. This allows the formation of a modified matrix (as opposed to the straightforward weighted average of coefficients of differential equations) which approximates the time-evolution operator for the vector of state variables. Calculations are compared with experimental results