Piecewise Quadratic Slope Compensation Technique for DC-DC Switching Converters

In this paper, a piecewise quadratic slope compensation technique for eliminating subharmonic oscillations in dc-dc switching converters is studied. With this technique, a self-generated signal is used in the compensation scheme resulting in a naturally full duty cycle stability domain. The expression of the piecewise quadratic compensating signal within a switching cycle is derived. It is obtained that the steady-state value of the amplitude of this signal is the same as in the conventional linear slope compensation scheme that guarantees stability for all values of the duty cycle. However, in the piecewise quadratic scheme this is achieved without exact knowledge of the inductance value nor sensing the input and the output voltages. The stability of the converter under the considered compensation scheme is also guaranteed for all values of the duty cycle with voltage loop open. A boost converter under peak current mode control is used to validate the theoretical results both by numerical simulations and by experiments. Simulation results are analyzed and compared to the performances of the state-of-art techniques with voltage loop closed.