Converter Design Process Research Articles

Multiobjective Design and Benchmark of Wide Voltage Range Phase Shift Full-Bridge DC/DC Converters for EV Charging Application

This paper presents an analysis, multi-objective design, and benchmark of three modified Phase-Shift Full-Bridge (PSFB) converters that are well-suited for Electric Vehicle (EV) battery charging applications, covering both typical battery voltage classes (400V and 800V). These three modified PSFB converters, denoted as the t-PSFB, r-PSFB, and i-PSFB converters, have the ability to reconfigure and provide better efficiency performance in the wide voltage range necessary for public EV battery charging applications. In this paper, the characteristics and design considerations of these reconfigurable PSFB converters are discussed in detail. A multi-objective converter design process is proposed to optimize the average efficiency, normalized cost, and power density of the magnetic components and heat sinks. This design process employs the correlations between the cost and performance indexes of the key components derived based on open and accessible components data to estimate the design objectives. In this way, the design process is not constrained by certain component choices, making it easier to identify the most advantageous design. A benchmark study is conducted among the re-configurable PSFB topologies and the conventional PSFB circuit using the proposed multi-objective design process. To validate the analysis, a close-to-Pareto-front 11kW, 45kHz r-PSFB converter prototype with 640-840V input voltage and 250-1000V output voltage ranges is developed and tested.

A Basic Design Tool for Grid-Connected AC–DC Converters Using Silcon Carbide MOSFETs

The design and optimization of power converters is a key factor in the growth and development of the power electronics field. However, the process of designing a power converter is not straightforward, and engineers often rely on experience and intuition, sometimes requiring time-consuming computer simulations. This paper presents a tool for the basic design of grid-connected AC–DC converters. The design tool takes specifications and operating conditions for two-level and three-level NPC converter topologies and derives a draft design. The tool calculates the input filter’s electrical parameters, the converter’s losses, the temperature rise of the power semiconductor devices, and the ripple current and voltage of the DC-link capacitor. In order to validate the proposed design tool, four AC–DC converters using SiC MOSFETs were designed. Based on the design results, simulation models and prototypes were fabricated to verify the performance and confirm that the proposed design tool can be used in the basic design process of converters.

Passive Component Optimization for Current-Source-Inverters

In addition to the actual semiconductor components and the cooling solutions required to dissipate losses, passive components account for a large part of the volume of power electronic converters. This publication presents methods for optimising the volume or occupied PCB board area of the passive components of current source inverters (CSIs). For this converter topology, these are primarily composed of the filter capacitors placed on the output terminals and the DC link inductance acting as the main energy storage device in the DC link. Design equations for the design of these components are presented first. In addition to the basic relationships for determining the capacitance or inductance of the respective components, other constraints for their design are also taken into account. Furthermore, an optimisation process is given for both the filter capacitors and the DC link inductance, with which the volume or the occupied board area of the respective components can be designed as small as possible. On the basis of the optimisation results for various input parameters, analytical relationships are then determined that can be used to quickly and easily estimate the volume and area at the beginning of a converter design process.

Guest Editorial Special Issue on Emerging Converter Topology, Operation, and Design Technologies

Power electronics play a key role in the transition to carbon neutrality. To enhance the performances of power electronics systems, new theories and methods are entering the field of power converter research, leading to increasing diversity of the knowledge database regarding converter design and operation methods. In addition to the conventional case-bycase design methodology, new automated and generalized converter design philosophies integrating topology derivation and synthesis methods, optimal pulse-width modulation (PWM), and advanced control strategies are gaining attention in both academia and industry. By implementing these methods, the converter design process can be greatly improved while the potentials of various power converters can be fully explored, leading to elevated converter performances.

AC Current Ripple in Three-Phase Four-Leg PWM Converters with Neutral Line Inductor

This paper presents a comprehensive study of peak-to-peak and root-mean-square (RMS) values of AC current ripples with balanced and unbalanced fundamental currents in a generic case of three-phase four-leg converters with uncoupled AC interface inductors present in all three phases and in neutral. The AC current ripple characteristics were determined for both phase and neutral currents, considering the sinusoidal pulse-width modulation (SPWM) method. The derived expressions are simple, effective, and ready for accurate AC current ripple calculations in three- or four-leg converters. This is particularly handy in the converter design process, since there is no need for heavy numerical simulations to determine an optimal set of design parameters, such as switching frequency and line inductances, based on the grid code or load restrictions in terms of AC current ripple. Particular attention has been paid to the performance comparison between the conventional three-phase three-leg converter and its four-leg counterpart, with distinct line inductance values in the neutral wire. In addition to that, a design example was performed to demonstrate the power of the derived equations. Numerical simulations and extensive experimental tests were thoroughly verified the analytical developments.

Design of an Isolated Bidirectional Symmetric Resonant Converter

An isolated type bidirectional resonant converter is presented in this paper. Using a dual active bridge as the main topology and integrating symmetric resonant mechanism, the developed converter features an isolated type bidirectional resonant converter with bidirectional power conversion and electrical isolation capabilities to ensure working security and stability. The application of a symmetric resonant scheme enables the control range of input and output voltages to be widened and achieves soft switching during bidirectional power conversion. A converter design process covering all the bases is exhibited in this work. With the digital signal processor (DSP) TMS320F28335 being employed as the control core, the developed isolated bidirectional resonant converter can effectively handle the power conversion between the simulated 400 V DC grid and the energy storage battery ranging from 280 to 403 V. Based on a 1 kW capacity design, the test data reveal that the forward conversion efficiency from grid to battery can reach 93.25%, and the reverse conversion efficiency from battery to grid is as high as 94.60%.

The Wave Energy Converter Design Process: Methods Applied in Industry and Shortcomings of Current Practices

Wave energy is among the many renewable energy technologies being researched and developed to address the increasing demand for low-emissions energy. The unique design challenges for wave energy converter design—integrating complex and uncertain technological, economic, and ecological systems, overcoming the structural challenges of ocean deployment, and dealing with complex system dynamics—have lead to a disjointed progression of research and development. There is no common design practice across the wave energy industry and there is no published synthesis of the practices that are used by developers. In this paper, we summarize the methods being employed in WEC design as well as promising methods that have yet to be applied. We contextualize these methods within an overarching design process. We present results from a survey of WEC developers to identify methods that are common in industry. From the review and survey results, we conclude that the most common methods of WEC design are iterative methods in which design parameters are defined, evaluated, and then changed based on evaluation results. This leaves a significant space for improvement of methods that help designers make better-informed decisions prior to sophisticated evaluation, and methods of using the evaluation results to make better design decisions during iteration. Despite the popularity of optimization methods in academic research, they are less common in industry development. We end this paper with a summary of the areas of WEC design in which the testing and development of new methods is necessary, and where more research is required to fully understand the influence of design decisions on WEC performance.

Challenges of Implementing Higher-Frequency Magnetics in Wide-Bandgap Converters [Women in Engineering

Designing system-level converters can be complicated. The interweaved intricacies of modular converters to achieve higher voltages while maintaining stable controls and magnetics design must be considered. While there are many difficulties to overcome, the magnetics tend to be the most uncomfortable for power electronics engineers to define in the converter design process due to the lack of direct transition from design and simulation to final hardware outcomes.

Application of 25mΩ SiC MOSFETs in a 10kVA Grid-Connected AC/DC Converter

This paper presents a grid-connected 10 kVA AC/DC converter built with 25mΩ SiC MOSFETs. The converter design process was based on an optimization procedure, which was applied to find the parameters that provide efficiency of 98.5% and power density of 3 kWA/dm3. The 10 kVA prototype, including LCL filter, was built and tested in various operation modes showing very good performance and high efficiency. The AC/DC converter is also able to act as an active power filter compensating high-order harmonics of the grid current caused by diode rectifier.

Small signal modelling and implementation of push-pull based inverter with parasitics

Original scientific research The proposed PWM switch modelling technique is a simple method for modelling push-pull based single phase inverters operating in continuous conduction mode. In the design process of converters it is desirable to assess as many critical design parameters and parasitic effects by simulation as possible, since the control is hard to tune after fabrication. The main advantage of this method is its versatility and simple implementation. Furthermore, the introduced model also includes parasitic elements of the components to better estimate the converter behaviour. The resulting circuit is a time averaged model where all currents and voltages correspond to their averaged values. The validity of this model is verified by the given experimental results for a specified design example. This modelling technique helps to design the inverter effectively and better choosing the controller component values to achieve a good dynamic response. Finally, current mode controlled push-pull converter is simulated and compared with proposed modelling technique where a good accordance between them is revealed. Simulation analysis is done by Matlab 9 and Psim 6 software. The overall modelling estimation error was lower than 5 %.

Thermal analysis and design of a 75-W hybrid-type DC–DC converter for space applications

Hybrid DC–DC converters for space applications should be designed for operation at full rated power within the military specification for temperature range of −55 to +125°C. Hence, the thermal design is a crucial step in the design process of converter, ensuring that no component of the converter exceeds its rated maximum operating temperature. One of the objectives of this work is to guarantee that all electronic components operate below their maximum allowable temperature. For this purpose, a three dimensional model of a converter based on the finite element method was developed. Results based on numerical simulation were validated by experimental data from infrared camera. The total amount of dissipated power in every component was determined experimentally based on a prototype converter. In the case of a component with high power consumption, such as the field effect transistor, the increase in temperature was minimized by applying designed heat sink with a high-thermal-conductivity material.