S.D. Johnson

Bio: S.D. Johnson is an academic researcher from Martin Marietta Materials, Inc.. The author has contributed to research in topics: Transformer & High voltage. The author has an hindex of 1, co-authored 1 publications receiving 176 citations.

Comparison of resonant topologies in high-voltage DC applications

Abstract: Because of their tolerance of transformer nonidealities, resonant converters are considered to be well-suited to high-voltage applications. The series and parallel resonant topologies, as well as a newly discovered hybrid resonant topology are compared for high-voltage applications. Design criteria which incorporate transformer nonidealities are developed and used in the construction of high voltage prototypes for each topology. It is found that the parallel topology leads to the lowest peak switch current and the most ideal behavior. >

Step-Up DC–DC Converters: A Comprehensive Review of Voltage-Boosting Techniques, Topologies, and Applications

Abstract: DC–DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc–dc converters, this paper aims to comprehensively review and classify various step-up dc–dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques.

Self-Capacitance of High-Voltage Transformers

Abstract: The calculation of a transformer's parasitics, such as its self capacitance, is fundamental for predicting the frequency behavior of the device, reducing this capacitance value and moreover for more advanced aims of capacitance integration and cancellation. This paper presents a comprehensive procedure for calculating all contributions to the self-capacitance of high-voltage transformers and provides a detailed analysis of the problem, based on a physical approach. The advantages of the analytical formulation of the problem rather than a finite element method analysis are discussed. The approach and formulas presented in this paper can also be used for other wound components rather than just step-up transformers. Finally, analytical and experimental results are presented for three different high-voltage transformer architectures.

Fixed-frequency PWM series-parallel resonant converter

Abstract: A pulse-width-modulated (PWM) high-frequency link series-parallel resonant converter operating with fixed frequency is proposed. A simple analysis and design procedure are presented. The proposed configuration has a number of desirable features, such as high efficiency for very wide load variations with a narrow range of duty-cycle ratio control, and load short-circuit capability. Detailed experimental results obtained from a 48 V output, 500 W experimental converter are presented to verify the concept. >

Study and Implementation of a Current-Fed Full-Bridge Boost DC–DC Converter With Zero-Current Switching for High-Voltage Applications

Abstract: This paper presents a comprehensive study of a current-fed full-bridge boost dc-dc converter with zero-current switching (ZCS), based on the constant on-time control for high-voltage applications. The current-fed full-bridge boost converter can achieve ZCS by utilizing the leakage inductance and parasitic capacitance as the resonant tank. In order to achieve ZCS under a wide load range and with various input voltages, the turn-on time of the boost converter is kept constant, and the output voltage is regulated via frequency modulation. The steady-state analysis and the ZCS operation conditions under various load and input-voltage conditions are discussed. Finally, a laboratory prototype converter with a 22-27-V input voltage and 1-kV/1-kW output is implemented to verify the performance. The experimental results show that the converter can achieve high output voltage gains, and the highest efficiency of the converter is 92% at full-load condition with an input voltage of 27 V.

Study and Implementation of a Single-Stage Current-Fed Boost PFC Converter With ZCS for High Voltage Applications

Abstract: The study and implementation of a single-stage current-fed full-bridge boost converter with power factor correction (PFC) and zero current switching (ZCS) for high voltage application is presented in this paper. The single-stage current-fed full-bridge boost PFC converter can achieve ZCS by utilizing the leakage inductance and parasitic capacitance as the resonant tank. The variable frequency control scheme with ZCS is used to regulate the output voltage and achieve high power factor. The operating principle, steady-state analysis, and control method of this single-stage AC-DC PFC converter are provided. Also, the ZCS operational conditions under various operational conditions are discussed. The design guidelines are given and verified by a laboratory prototype converter with 200 ~ 240 Vrms input voltage and a 4 kV/1.2 kW output. In order to reduce the switching losses, the highest switching frequency is constrained at 160 kHz. So, the switching frequency of the prototype converter is 50~160 kHz. The measured power factor is 0.995 and the efficiency is 87.4 at full-load condition with an input voltage of 220 Vrms. The laboratory prototype converter can be operated at ZCS under full range by carefully designing the circuit parameters.