This paper proposes a digital hysteresis-modulation technique based on switching-time prediction. Sampling controlled variables several times within a switching period, it ensures a dynamic performance comparable to that obtainable with analog hysteresis modulation. Compared to conventional digital hysteresis modulation, it avoids frequency jitter since it predicts switching transitions. Compared to hysteresis modulation based on the detection of the zero crossing of current errors, it avoids external analog circuits. Compared to pulsewidth-modulation (PWM) techniques, it ensures faster dynamic response. These advantages are obtained at the expense of increased signal-processing requirements and of control complexity. Switching-frequency stabilization and synchronization with an external clock can be obtained extending the techniques proposed for analog hysteresis modulations. The proposed predictive algorithm does not require knowledge of load parameters and only a rough estimation of the inductor value, which can be easily self-adjusted. The proposed solution is suited for high-performance current (or sliding-mode) control where the digital hardware has enough computational power to allow multiple samples within a switching period. The proposed modulation technique has been applied to a sliding-mode control of a single-phase uninterruptible power supply (UPS). Experimental results confirm the effectiveness of the proposed approach

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This paper investigates the multisampling techniques applied to the current control in active-power-filter (APF) applications. In APF applications with digital control, the main bandwidth limitation derives from A/D conversion and computational delays and the sampling-related delay of the digital pulsewidth modulation (DPWM). Using field-programmable gate arrays and fast A/D converters for the control implementation, it is possible to minimize the former two; thus, the overall phase lag is dominated by the DPWM, which can strongly be reduced by the multiple-sampling approach, breaking bandwidth limitations of single-sampled solutions. Moreover, as the multisampling approach triggers nonlinear behaviors that can negatively impact the filter-compensating capabilities, a solution based on a simple digital filter is proposed which linearizes the system behavior and does not waste the multisampling advantages. Simulation and experimental results on a 10-kVA prototype confirm the theoretical expectations

This letter proposes a simple tuning algorithm for digital deadbeat control based on error correlation. By injecting a square-wave reference input and calculating the correlation of the control error, a gain correction for deadbeat control is obtained. The proposed solution is simple, it requires a short tuning time, and it is suitable for different DC-DC converter topologies. Simulation and experimental results on synchronous buck converters confirm the properties of the proposed tuning algorithm