Switched Mode Power Supplies

This paper describes the application of
TL494 PSPICE MODEL with OrCAD Capture for
analyzing switching regulators, which can assist
beginners like undergraduate students in understanding
the switching regulators. This paper mainly focuses on
application of simulation model as none of the
literatures provides required information to work with
TL494 simulation model. Although TL494 chip is a
very simple chip as far as hardware is concerned, it is
not easy work with Pspice model of TL494 without
adequate knowledge about the Pspice software. The
application of this chip’s simulation model with OrCAD
Capture is demonstrated with the help of buck
converter. This application report can also be extended
to other non-isolated as well as isolated converters.

Multi-objective optimization of power converters is a time-consuming task, especially when multiple operating points and multiple converter topologies must be considered. As a result, various steps are often taken to simplify the design problem and restrict the size of the design space prior to going through an optimization procedure. While this saves time, it produces potentially sub-optimal designs, and existing approaches must trade-off between running time and design optimality. This paper presents an optimization-oriented method for modeling power converters and their components as posynomial functions, allowing multi-objective optimization of converters to be formulated as a geometric program, a type of convex optimization problem. This allows the use of fast, powerful solvers that guarantee global optimality of solutions. The method is demonstrated using the example of low-power multi-level flying capacitor step-down converters. Results show that, using geometric programming, sets of globally Pareto-optimal designs of 2-, 3-, and 4-level converters with respect to efficiency and power density, for one design space and one operating point, can be generated in as little as 25 seconds, on an mid-to upper-range laptop computer. Thus optimal designs for three different converter topologies for hundreds of different operating points and/or design spaces can be generated in several hours-less than the time required to globally optimize one converter topology at one operating point for one design space using currently prevalent methods. The paper also demonstrates how geometric programming can be used to quickly perform sensitivity and trade-off analysis of optimal converter designs.

In this paper, we present the significance of
computer simulation program, such as ORCAD
PSPICE, in analyzing, first order approximations of
circuit behavior, a closed loop, non-isolated dc-dc
converter with synchronous rectifier circuit. Following
techniques have been adopted to simplify the process of
simulation. They are: (1) Ideal switches are incorporated
in the power stage of the converter to eliminate the gate
diver requirement which in turn reduces the simulation
run time; (2) Diodes are connected in series with
switches, which eliminates dead time control circuit, to
prevent cross conduction of switches and (3) TL494
Pspice model, which is readily available in library of
most of the versions of the ORCAD PSPICE, is
employed for pulse width modulation. As an example,
non-inverting synchronous buck boost converter is
considered for demonstrating the approach. Simulation
was carried out for an input voltage range of 6 to 35V
and load resistance was varied from 12 to 48 Ohms.
Output voltage was regulated at 12V for both input
voltage and load current perturbation. Physical
prototype was implemented and simulation result was
tested for steady state output.

This paper presents the development and performance evaluation of a compact-converter-based power supply for plasma dielectric barrier discharge (DBD) devices. The developed power supply is designed to meet weight and size requirements for applications in aeronautical systems. Multistage and multilevel switch-mode converters are employed to construct the power supply. The multistage part of the power supply is constructed from multiple dc-dc boost converters that have their inputs fed by rechargeable batteries. The outputs of the dc-dc converters are used to feed different levels of a single phase cascaded H-bridge (CHB) multilevel dc-ac converter. The switching signals for the CHB dc-ac converter are generated to facilitate the adjustments of the magnitude and/or frequency of the output voltage. Such adjustments are set to allow manipulating the generated plasma body force. A prototype for the multistage multilevel power supply is constructed for performance evaluation using a fiberglass DBD device. Performance results show an effective generation and control of plasma body force, which can be achieved by a modular, lightweight, and compact size power supply.

Recently, it has been shown that geometric programming , a class of convex optimization problems, can be used to optimize converters quickly and accurately. Some however, such at the seven-switch flying capacitor step-down converter (7SFC), designed to operate in three modes as three distinct topologies in order to maximize efficiency for the given operating point, cannot be modeled as geometric programs (GPs) on the converter level. This paper presents a hybrid optimization procedure, generalizable to other topologies, that uses a GP coupled to a fast circuit simulation to quickly optimize and design a 7SFC power stage IC for multiple operating points.

Designing the feedback compensator for the SEPIC
(single ended primary inductance converter) converter is quite
difficult due to the extreme amount of phase shift in the power
stage and occurrence of double resonance. Hence the current
mode control, which increases the complexity of the system, is the
most commonly adapted for stabilizing the converter. However,
the careful observation of the frequency response of power stage,
which depends on the filter components and equivalent series
resistance of the capacitor, of the power stage makes the process
of controlling the dynamics of the converter easy. Sometimes the
frequency response of the power stage of the converter is free
of double resonance with minimum phase shift and resembles
the second order converter. So, one can develop the compensator
network similar to the second order converter. In this paper, the
design of controller for the SEPIC converter based on single loop
feedback control is presented without the need of current mode
control and its associated complexity. The presented analysis
does not require the complicated methods such as the principal
component analysis and the model order reduction but it is as
simple as observing the bode plot of the power stage of the
converter. The entire simulation is carried out in Pspice.

In this paper, a novel high conversion ratio DC-DC converter suitable for photovoltaic applications is presented. Utilizing single-switch and single-magnetic core, low ripple input current and low voltage stress across the semiconductors are the major advantages of the proposed converter. In order to provide soft-switching condition for the converter switch at a wide range of output power, a passive lossless snubber is employed. The presented converter is adequate for photovoltaic applications due to mentioned properties. Operating principles are analyzed and design considerations are provided. In order to validate the theoretical analysis, a prototype of the proposed converter is implemented and the experimental results are exhibited.