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In the conventional digital peak current (DPC) predictive controlled switching dc-dc converters, the duty ratio in each switching cycle is usually calculated and predicted based on the status of the previous switching cycles. Therefore at least one-switching-cycle time delay usually exists in such a predictive control technique, which significantly degrades the control performance of digitally controlled switching dc-dc converters. To eliminate this one-switching-cycle time delay and to improve the control performance, an improved digital peak current (IDPC) predictive control technique for switching dc-dc converters is then proposed and studied in this study. The control laws of DPC and IDPC control with different pulse width modulations are derived and their stabilities are analysed. A simple digital slope compensation method is proposed to eliminate the sub-harmonic oscillations of DPC and IDPC control laws. Steady-state and transient performances of DPC- and IDPC-controlled buck converters are investigated and compared by experimental results. The comparison studies between DPC and IDPC control show that transient performance of IDPC is much better than that of DPC.
Date of Publication: February 2011