This paper introduces an approach to achieve optimum dead times in dc–dc converters with synchronous rectifiers without sensing any of the power-stage signals other than the output voltage. The dead times are adjusted adaptively to minimize the duty-cycle command, which results in maximization of the converter efficiency. The method is particularly well suited for digital controller implementation, requiring no additional analog components or modifications of standard gate-drive circuitry. Experimental results for a digitally controlled 5 V-to-1 V, 5-A synchronous buck converter demonstrate practical implementation of the sensorless dead-time optimization algorithm.

Sensorless optimization of dead times in dc–dc converters with synchronous rectifiers

In this paper, an overview of recent advances in digital control of low- to medium-power dc/dc switching converters is presented. Traditionally, such dc/dc converters have been almost exclusively controlled through analog electronics methods. However, with the steadily decreasing cost of ICs, the feasibility of digitally controlled dc/dc switching converters has increased significantly. This paper outlines some of the existing design challenges related to digital control and reviews a sample of recently proposed solutions. In addition, present-day research pertaining to applications such as online efficiency optimization, controller autotuning, and specialized nonlinear control is presented. Such applications demonstrate the true advantages and potential of digital control as their complexity prevents practical implementation in the analog domain.

Recent Developments in Digital Control Strategies for DC/DC Switching Power Converters

Power converter interfaces for electrochemical energy storage systems – A review

This paper investigates the sampled-data output feedback control problem for dc-dc buck power converters taking consideration of components uncertainties. A reduced-order observer and a robust output feedback controller, both in the sampled-data form, have been explicitly constructed with strong robustness in the presence of uncertain parameters. A delicate stability analysis process is presented to show that, by carefully selecting the design gains and the tunable sampling period, the output voltage of the hybrid closed-loop dc-dc buck converter system will globally asymptotically tend to the desired value even though the separation principle is out of reach and the controller is only switched at the sampling points. The proposed controller consists of a set of linear difference equations which will lead to direct and easier digital implementation. Numerical simulations and experimental results are shown to illustrate the performance of the proposed control scheme.

Robust Control for PWM-Based DC–DC Buck Power Converters With Uncertainty Via Sampled-Data Output Feedback

This study presents a new DC-DC multi-output boost (MOB) converter which can share its total output between different series of output voltages for low- and high-power applications. This configuration can be utilised instead of several single output power supplies. This is a compatible topology for a diode-clamed inverter in the grid connection systems, where boosting low rectified output-voltage and series DC link capacitors is required. To verify the proposed topology, steady-state and dynamic analyses of a MOB converter are examined. A simple control strategy has been proposed to demonstrate the performance of the proposed topology for a double-output boost converter. The topology and its control strategy can easily be extended to offer multiple outputs. Simulation and experimental results are presented to show the validity of the control strategy for the proposed converter.

/pdf/multi-output-dc-dc-converters-based-on-diode-clamped-1wnxnjh2wp.pdf

Multi-output DC-DC converters based on diode-clamped converters configuration: topology and control strategy

The objective of this paper is to propose a simple digital current mode control technique for dc-dc converters. In the proposed current-mode control method, the inductor current is sampled only once in a switching period. A compensating ramp is used in the modulator to determine the switching instant. The slope of the compensating ramp is determined analytically from the steady-state stability condition. The proposed digital current-mode control is not predictive, therefore the trajectory of the inductor current during the switching period is not estimated in this method, and as a result the computational burden on the digital controller is significantly reduced. It therefore effectively increases the maximum switching frequency of the converter when a particular digital signal processor is used to implement the control algorithm. It is shown that the proposed digital method is versatile enough to implement any one of the average, peak, and valley current mode controls by adjustment of the sampling instant of the inductor current with respect to the turn-on instant of the switch. The proposed digital current-mode control algorithm is tested on a 12-V input and 1.5-V, 7-A output buck converter switched at 100kHz and experimental results are presented

A Digital Current-Mode Control Technique for DC–DC Converters

This paper introduces a digital average current-mode controller architecture based on a low-resolution current A/D converter and a simple digital controller realization. The proposed approach combines advantages of practical digital realization and current-mode control for DC-DC converters operating at high switching frequencies. An experimental test circuit includes an experimental prototype current A/D converter, a controller implemented on an FPGA, and a 6 V-to-1.8 V, 10 A synchronous buck power stage operating at 200 KHz. Experimental verification results are described

Somshubhra Das

Papers

A Digital Current-Mode Control Technique for DC–DC Converters

A digital current mode control technique for DC-DC converters