In this paper we propose an automatic controller design methodology for DC-DC converters that comprehensively addresses both Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). This methodology leverages on Artificial Intelligence (AI) techniques. Specifically, we resort on the Genetic Algorithms (GA) and Particle Swarm Optimization (PSO) methods. Both GA and PSO permit to optimally tune the component values employed in the compensation network, overcoming the limitations of traditional design methods. The latter focus indeed solely on CCM, leading to significant performance degradation in DCM operation. The proposed methodology can be seamlessly integrated into DC-DC converter design phase, and it is not restricted for specific DC-DC topologies or control architectures. As a case study, we apply the proposed approach to the design of a Type-Iii compensation network in a voltage-mode controlled Buck converter, aiming to improve the load-transient response. The optimization process is carried out in MATLAB. Then, a performance comparison with the conventionally designed controller is conducted via SIMPLIS simulations. An improvement in overall performance is demonstrated.

In this paper, we present a novel and unified small-signal modeling technique for Pulse-Width Modulated (PWM) DC-DC Buck converters with Ripple-Based Constant On-Time (RBCOT) control. In fact, despite the spread of RBCOT-based converters in several applications requiring tight dynamic performances and a low architectural complexity, their description through small-signal models is not always as reliable as that of fixed-frequency PWM control architectures, and a general and exact modeling framework is not well established. The proposed methodology is grounded on the DC-DC converter state-space representation and thus, differently from other modeling techniques, it permits to fully characterize the dynamic behavior of generic RBCOT converter topologies with arbitrary complex power stage and ripple injection networks. As a case study, we derive the small-signal model for a Buck converter embedding a widely used ripple injection network in industrial applications. The validity of the theoretical results is confirmed through direct comparison with SIMetrix/SIMPLIS simulations and experimental measurements in practical application scenarios, confirming the accuracy of the model even well beyond the converter switching frequency.

We investigate here both from a theoretical and practical point of view the problem of optimizing EMI reduction by means of spread spectrum clocking when lower harmonics need to be analyzed with a smaller RBW, and higher harmonics with a larger one. This situation is indeed a trade-off, where a designer can trade performance in terms of EMI reduction for lower harmonics with that achieved for higher harmonics. Two approaches are considered and analyzed. The first trade-off, denoted as Single Triangular Modulation, consists in the standard and commonly adopted triangular based spreading, where the role of the parameters is investigated with the aim of optimizing EMI reduction both in the lower part and the upper part of the spectrum. The second one, denoted as Double Triangular Modulation, is inspired by a recent Application Note and it is much more complex from an implementation point of view, being based on two simultaneous triangular modulations with different parameters. The comparison shows very similar performance, so that the adoption of the more complex approach results questionable.

In this paper we provide an improved small-signal equivalent circuit model of a synchronous Buck converter which operates in Continuous Conduction Mode (CCM) and includes an alternative Zero Voltage Switching (ZVS) mechanism for the low-side power MOSFET that rely on the MOSFETs output capacitance. The addressed analysis improves the state of the art in DC/DC small-signal modeling as it is capable to predict unexpected effects on the dynamical system response such as the dependency on input voltage introduced by parasitics. Therefore, a complete design tool which permits to evaluate the impact of the MOSFETs output capacitance and the ZVS network on the converter dynamics is proposed. The derived equivalent circuit model which includes an additional feedforward path and a feedback loop is analyzed and the main open-loop transfer functions (control-to-output, line-to-output, output impedance) are analytically assessed. A verification has been carried out through SIMPLIS circuital simulations, corroborating the validity of the whole evaluation process.