Control Algorithms And Implementation Of Digitally Controlled Dc-dc Converters

With the decreasing of the characteristic metal width of CMOS process, the integration of digital circuits continues increasing such that more and more complex functionalities can be accomplished. The field of the power supply has been dominated by the analog solutions for a long time, while people have tried to design power products with digital technology since the performance-price ratio of digital circuits (such as DSP and MCU) continues increasing. With the excellent work accomplished in the past several years, the digital power products have become more and more attractive and have had several unique features that can’t be owned by any traditional analog products. Based on this background, research of digital power supply continues to deepen and more advantages of adopting digital technology in power field are expected that can finally result in the revolutionary advancement in the power field.This thesis focuses on dc-dc converters as the important part of the power electronics in two aspects of control algorithms and module circuits, in which several are the former valuable results and several are the innovative results after study.As the necessary basis for understanding the digitally controlled dc-dc converters, the knowledge related to general dc-dc converters is first introduced. This knowledge includes various output stage topologies, various loop control methods, various operating states of inductor current, various pulse modulation methods and the main performance requirements. Based on this knowledge, the thesis discusses the basic theories about the digitally controlled dc-dc converters including the architecture and the main modules, the loop characteristics, and the unique features of the digital technology in power field. Meanwhile, the thesis also points out the unsolved issues and the unsuitable applications.The performance optimization of the digitally controlled dc-dc converters is analyzed in the next chapter. The most important index conversion efficiency for converters is focused on at first. The theoretical analysis is given on the optimal dead-time and the optimal switching frequency, which indicates that the efficiency optimization can be obtained by adopting the acquisition of the optimal working point in digital technology. It is next analyzed that the efficiency optimization under overall load conditions using automatic state switching under different loads. The three dynamic characteristics (loop stability, output ripples and transient response) are discussed in the rest of this chapter.Then the thesis exhibits the application of digital technology in single-output, multiple-output converters and multiphase converters in the next three chapters. In the every chapter, the features and technique issues are first introduced, and the existing solutions and their disadvantages are given next, then the new digital solution and its suitable applications are finally given.As the most direct validation, the chip implementation of a bulk dc-dc converter is next given, which includes circuitries, layout, simulation and tests. The existed issues and possible improvements are also discussed.The conclusion and the prospect of employing the digital technology in LED driver, photovoltaic energy generation and ac-dc converters are given in the end of the thesis.