دانلود رایگان کتاب (Switch Mode Power Converters Design Analysis (Keng_C._Wu
کتاب آنالیز طراحی مبدل قدرت سوئیچ مد (Keng_C._Wu):
Switch Mode Power Converters Design Analysis
This is not a cookbook, for switch-mode power converter design is a serious topic that must be treated with the utmost care. Therefore, the book makes a major departure from most existing texts covering the same subjects. It uses mathematics extensively, employing, for example, symbolic closed-form solutions for conduction times of a loaded fullwave rectifier with a capacitor filter. At the first sight, readers may feel discouraged, but there is no shortcut. I sincerely urge readers to be patient, for the reward is profound. The book covers in depth the three basic topologies: step-down (buck, forward), step-up (boost), step-down/up (flyback); push–pull; current-fed; resonant converters and their derivatives; AC–DC power factor correction. Depending on the operating conditions, switch-mode power converters may operate either in continuous conduction mode (CCM) or discontinuous conduction mode (DCM). Under transient conditions, the operation of power converters may slide in and out of both modes. For closed-loop control of converters, two fundamental mechanisms, voltage-mode control or current-mode control, are generally employed. Current-mode control has been understood to offer superior performance. Current mode control is further subdivided into average-current control and peak-current control. While most switchmode converters utilize pulse-width modulation, resonant converters use frequency modulation. In addition to the main operation mechanism, many supporting circuits are also needed to make power converters viable. These include switch drivers, error amplifiers, and feedback isolators.
The presentation follows a fairly consistent pattern. The relationship between steady-state output and control variables (duty cycle, in the case of PWM, or frequency, in the case of resonance) is established first for both the CCM and the DCM operation. By examining the cyclical current waveforms of CCM, geometrical properties of the waveforms are extracted. These lead to the identification of critical inductance, which marks the boundary distinguishing CCM and DCM operation.
Under each operation mode and given a selected control mechanism, steady-state closed-loop output formulation that includes feedback ration, error amplifier, PWM gain (or frequency-modulation gain), and power stage is then established. In some simplified cases that exclude losses, the output formulation may be placed in the explicit form. When losses are included, the desire to obtain an explicit form is prohibitively impractical and abandoned. Instead, implicit functions and Jacobian determinants are employed to study output sensitivity and regulation.
With the steady state firmly established, the small-signal AC stability issues are examined for both control modes. Loop stability with voltagemode control based on the average model (Dr. R. Middlebrook) is formulated and validated. Current-mode control necessitates the addition of current-loop gains surrounding the original average mode. In effect, the Middlebrook average model is extended to current-mode control and remains as valid.
This book also introduces accelerated steady-state analysis in the time domain. The technique connects the concept of the continuity ofstate and the periodic, steady-state output of converters. The analysis uses two approaches: Laplace transformation and state transitions. The latter calls on eigenvalues, eigenvectors, and matrix exponentials, the core of matrix theory associated with system theory. Nowadays, simulations always play some role in almost all fields of studies. For power converters, there is no exception. This book, however, approaches it from a more fundamental way, which is quite distinctive from the graphic-based simulations available commercially. The latter suffers convergence issues frequently. Our approach avoids such nagging difficulties.
The book is written for those already exposed to the basics of switchmode power converters and seek higher dimensions. It is suitable for graduate students and professionals majoring in electrical engineering. In particular, readers with training in linear algebra will find the techniques of state transition being applied very inspiring.
Finally and most importantly, profound gratitude is extended to Charles B. Glaser, senior acquisition editor and his staff at Elsevier Inc., Burlington, MA; Annie Martin, production director, Elsevier Ltd., England; and Sheryl Avruch, copyeditors, typesetters, and staff at SPI Publisher Services.
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