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Most electronic ballasts for fluorescent lamps provide a sinusoidal lamp current at the switching frequency. The high-frequency current flowing through the lamp can generate significant radiated noise, which is unacceptable in noise-sensitive applications, such as fluorescent lights in airplanes. Using shielded enclosures for the lamps may solve the problem, but it is expensive. A discontinuous conduction mode (DCM) electronic ballast topology is presented which drives the lamp with line frequency current, just like a magnetic ballast. However, compared to a magnetic ballast, its weight is substantially reduced due to operation at 40 kHz switching frequency. The topology also ensures unity power factor at the input and stable lamp operation at the output.

A novel single active switch two-diodes high-voltage converter is presented. This converter can operate into a capacitor-diode voltage multiplier, which offers simpler structure and control, higher efficiency, reduced electromagnetic interference (EMI), and size and weight savings compared with traditional switched-mode regulated voltage multipliers. Two significant advantages are the continuous input current and easy isolation extension. The new converter is experimentally verified. Both the steady-state and dynamic theoretical models are correlated well with the experimental data

Accuracy of a direct measurement of core-loss power is severely limited in many applications by the extra phase shift between the measured voltage and current. An analysis of the error is for the first time performed, which not only unfolds the hidden physical nature behind it, but also reveals a simple and effective method to control the sensitivity and hence the error. This method can also be used to satisfy a prescribed tolerance. Extensive measurements on a TDK PC40 core yield results which support the analysis.

A new large-signal nonlinear control technique is proposed to control the duty-ratio d of a switch such that in each cycle the average value of a switched variable of the switching converter is exactly equal to or proportional to the control reference in the steady-state or in a transient. One-cycle control rejects power source perturbations in one switching cycle; the average value of the switched variable follows the dynamic reference in one switching cycle; and the controller corrects switching errors in one switching cycle. There is no steady-state error nor dynamic error between the control reference and the average value of the switched variable. Experiments with a constant frequency buck converter have demonstrated the robustness of the control method and verified the theoretical predictions. This new control method is very general and applicable to all types of pulse-width-modulated, resonant-based, or soft-switched switching converters for either voltage or current control in continuous or discontinuous conduction mode. Furthermore, it can be used to control any physical variable or abstract signal that is in the form of a switched variable or can be converted to the form of a switched variable.

One-cycle control is a nonlinear control method. The flow-graph modeling technique is employed to study the large-signal and small-signal dynamic behavior of one-cycle controlled switching converters. Systematic design method for one-cycle control systems is provided with the Ćuk converter as an example. Physical insight is given which explains how one-cycle control achieves instant control without infinite loop gain. Experimental results demonstrate that a Ćuk converter with one-cycle control reflects the power source perturbation in one-cycle and the average of the diode voltage follows the control reference in one cycle.

A unified graphical modeling technique, “Switching Flow-Graph” is developed to study the nonlinear dynamic behavior of pulse-width-modulated (PWM) switching converters. Switching converters are variable structure systems with linear subsystems. Each subsystem can be represented by a flow-graph. The Switching Flow-Graph is obtained by combining the flowgraphs of the subsystems through the use of switching branches. The Switching Flow-Graph model is easy to derive, and it provides a visual representation of a switching converter system. Experiments demonstrate that the Switching Flow-Graph model has very good accuracy.

A practical approach for magnetic core loss characterization up to a few megahertz is presented. An error analysis is performed, revealing that corrections are needed to compensate for errors introduced by extra phase shifts inherent in a measurement setup, and by shunt parasitic capacitance associated with an inductive device under test. A simple technique is proposed to control the error, so as to satisfy prescribed tolerances. Extensive meassurements done on a TDK PC40 core yield results which support the analysis. Several sample cores are then characterized at a few megahertz.

A method for systematic synthesis of quasi-resonant (QR) topologies by addition of resonant elements to a parent pulse-width modulation (PWM) converter network is proposed. It is found that there are six QR classes with two resonant elements, including two novel classes. More complex QR converters can be generated by a recursive application of the synthesis method. Topological definitions of all known and novel QR classes follow directly from the synthesis method and topological properties of PWM parents. The synthesis of QR converters is augmented by a study of possible switch realizations and operating modes. In particular, it is demonstrated that a controllable rectifier can be used to accomplish the constant-frequency control in all QR classes. Links between the QR converters and the underlying PWM networks are extended to general DC and small-signal AC models in which the model of the PWM parent is explicitly exposed. Results of steady-state analyses of selected QR classes and operating modes include boundaries of operating regions, DC characteristics, a comparison of switching transitions and switch stresses, and a discussion of relevant design trade-offs.

An additional independent control needed to eliminate the undesirable variable switching frequency of quasi-resonant converters can be obtained if the output rectifier is replaced by an active switch. The concept is applicable to all classes of quasi-resonant converters. It is demonstrated that in addition to operation at constant switching frequency, selected classes of constant-frequency quasi-resonant (CF-QR) topologies feature extended range of accessible conversion ratios and load currents. A practical example of a constant-frequency multi-resonant (CF-MR) buck converter operating at 2 MHz is described.

Three discontinuous operating modes of PWM (pulsewidth modulated) converters are considered: the discontinuous inductor current mode (DICM), the discontinuous capacitor voltage mode (DCVM), and a previously unidentified mode called the discontinuous quasi-resonant mode (DQRM). DC and small-signal AC analyses are applicable to all basic PWM converter topologies. Any particular topology is taken into account via its DC conversion ratio in the continuous conduction mode. The small-signal model is of the same order as the state-space averaged model for the continuous mode, and it offers improved predictions of the low-frequency dynamics of PWM converters in the discontinuous modes. It is shown that converters in discontinuous modes exhibit lossless damping similar to the effect of the current-mode programming.

In dc-to-dc conversion applications that require a large range of input and/or output voltages, conventional PWM converter topologies must operate at extremely low duty ratios, which limits the operation to lower switching frequencies because of the minimum ON-time of the transistor switch. This is eliminated in a new class of single-transistor PWM converters featuring voltage conversion ratios with quadratic dependence on duty ratio. Practical circuit examples operating at 0.5 MHz are described.

The recently introduced new optimum topology dc-to-dc converter is extended in a simple and elegant manner to provide dc isolation and multiple outputs. In comparison with the single-transistor isolated forward and flyback converters operated under the same conditions, the single-transistor isolated new converter is shown to have equal or lower stress levels on the transistor, diode, and capacitor ripple current, and can utilize an isolation transformer with lower core and copper losses. Measurements of cross- and self-regulation properties of a two-output 45 W test converter are presented.

A novel switching dc-to-dc converter is presented, which has the same general conversion property (increase or decrease of the input dc voltage) as does the conventional buck-boost converter, and which offers through its new optimum topology higher efficiency, lower output voltage ripple, reduced EMI, smaller size and weight, and excellent dynamics response. One of its most significant advantages is that both input and output current are not pulsating but are continuous (essentially dc with small superimposed switching current ripple), this resulting in a close approximation to the ideal physically nonrealizable dc-to-dc transformer. The converter retains the simplest possible structure with the minimum number of components which, when interconnected in its optimum topology, yield the maximum performance. The new converter is extensively experimentally verified, and both the steady state (dc) and the dynamic (ac) theoretical model are correlated well with the experimental data. both theoretical and experimental comparisons with the conventional buck-boost converter, to which an input filter has been added, demonstrate the significant advantages of the new optimum topology switching dc-to-dc converter.

A large-signal switching regulator model is derived, and prominent features of the transient response are determined. In particular, analytical expressions are found for the equilibrium points of the system which yield insight into the large-signal response, and computer-generated transient waveforms are obtained. As an example, a boost regulator is investigated, and is found to be stable for small signals but unstable for large transients.

A new optimum topology dc-to-dc switching converter is extended to provide bidirectional current flow. The resulting two-quadrant converter can be employed to eliminate the discontinuous current mode in normal unidirectional applications, but is especially suited for spacecraft battery conditioning as a charge-discharge regulator in place of the conventional separate converters. Implementation of the control features and the battery charge current and voltage limits are discussed.

Systematic extension of any dc-to-dc converter leads to its dc-to-three-phase equivalent characterized by sinusoidal output voltages and fast dynamic responses. This genralization principle is illustrated for the special case of the flyback topology. State-space averaging has modeled with a high degree of accuracy the performance of dc-to-dc converters. Here it is combined with the stationary-to-rotating coordinate transformation, customarily used in polyphase ac systems, to results in an effective analysis method for switched-mode dc-to-polyphase converters.

A method for modelling switching converters in the discontinuous conucction mode is developed, whose starting point is the unified state-space representation, and whose end results is a complete linear circuit model which correctly represents all essential features, namly, the input, output, and transfer properties (static dc as well as dynamic ac small signal). While the method is generally applicable to any switching converter operating in the discontinuous conduction mode, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model. The outlined method lends itself easily to investigation of the discontinuous conduction mode in more complex structures (cascade connection of buck and boost converters, for example), in which more thean one inductor current may become discontinuous. As opposed to other modelling techniques, the new method considers the discontinuous conduction mode as a special case of the continuous conduction mode.

Investigation of a wide variety of switching converter topologies culminates in the establishment of the most general correlation between the converter topologies--the duality relationships. The recognition of this general law leads to a number of new results: new converter topologies generated by the application of the duality transformation to the existing converter configurations, the discovery of the new mode of converter operation (discontinuous capacitance voltage mode) as well as significantly improved understanding of the existing converters and their equivalent circuit models.

The dc-to-dc conversion ratio of the series resonant converter has been determined in the general discontinuous and continuous condection modes. This new analysis gives a complete description of the dc operation of the circuit for any load and for any switching frequency.

A new switching dc-to-dc converter is synthesized which consists of the least number of storage elements (inductive and capacitive) and switches, and yet truly emulates the ideally desired dc-to-dc transformer having both input and output currents as pure dc quantities with no ripple. This result was facilitated by implementation of a new concept termed integrated magnetics, which leads in some special switching structures to the integration of otherwise independent and separate magnetic components (inductors and transformers) into a single magnetic circuit.