Elimination of Sampling-Induced Dead Bands in Multiple-Sampled Pulse Width Modulators for DC-DC Converters

In multiple-sampled pulse width modulators (MSPWM) the sampling frequency of the modulating signal is higher than the switching frequency of the power converter. MSPWMs have been shown to exhibit a drastically lower phase lag with respect to their single-sampled counterparts, thus allowing for higher closed-loop bandwidths to be achieved. However the increased sampling frequency gives rise to nonlinear phenomena called sampling-induced dead bands that negatively affect the system operation, as they introduce zero- differential gain regions in the modulator trans characteristic. This paper proposes a correction algorithm that allows for dead-band removal, thus making the PWM gain constant with respect to the imposed modulating signal. This result is achieved by a simple solution that can be easily implemented without specific hardware requirements. Simulation and experimental results on a dc-dc synchronous buck converter are provided to show the effectiveness and overall simplicity of the proposed solution.