| The scope of this work is the point-of-load (POL) and voltage regulator modules (VRM) DC-DC converters requirements, design and optimization. Topologies and control techniques for DC-DC converters are presented after reviewing loads powering requirements and DC-DC converters steady-state and transients design challenges and theoretical analysis.; Non-isolated multiphase voltage-mode hysteretic controlled DC-DC converter control scheme and topology with current sharing is presented and supported by theoretical analysis with output voltage ripple, switching frequency and stability condition equations along with experimental results.; Then, after reviewing selected isolated topologies, a control method for isolated half-bridge DC-DC converter topology, namely, Duty-Cycle-Shifted (DCS) control, is presented.; Another general control method for half-bridge topology, called Alternated Duty Cycle (ADC) control, is also presented. This method can achieve soft switching for half-bridge switches alternatively, if not for the two switches, and can do so without the penalty of asymmetric components stresses and isolation transformer DC bias, while improving efficiency and maintaining thermal balance of the half-bridge switches.; Also presented is the interleaving method for isolated topologies, where the secondary side switches operate at lower switching frequency than the primary side switches to improve efficiency and to improve transient response.; A Coupled-Inductors Current-Doubler (CICD) topology is then presented to allow further output voltage step-down by coupled inductors and to reduce the secondary side current-doubler input current. This is followed by a presentation of a non-isolated Half-Bridge-Buck (HBB) topology, where CICD topology can be also used, resulting in advantages including larger output voltage step-down and better self current sharing, especially when compared to non-isolated, two-phase buck topology. Theoretical analysis and experimental results are presented.; Digital control is discussed as a candidate for future DC-DC converters, while digital system structure, advantages, disadvantages and initial experimental setup are presented also. Moreover, an initial concept for future work on digital control is discussed, namely, the Maximum Efficiency Point Tracking (MEPT) method, which can be used to optimize a switche's dead time control issue by using adaptive control to achieve better efficiency and converter performance. (Abstract shortened by UMI.)... |
