Control design for efficient and cost-effective distributed fuel cell power electronics system

One of the most important problems in the widespread use of electric vehicles is the lack of charging infrastructure. Especially in tourist areas where historical buildings are located, the installation of a power grid for the installation of electric vehicle charging stations or generating electrical energy by installing renewable energy production systems such as large-sized PV (photovoltaic) and wind turbines poses a problem because it causes the deterioration of the historical texture. Considering the need for renewable energy sources in the transportation sector, our aim in this study is to model an electric vehicle charging station using PVPS (photovoltaic power system) and FC (fuel cell) power systems by using irradiation and temperature data from historical regions. This designed charging station model performs electric vehicle charging, meeting the energy demand of a house and hydrogen production by feeding the electrolyzer with the surplus energy from producing electrical energy with the PVPS during the daytime. At night, when there is no solar radiation, electric vehicle charging and residential energy demand are met with an FC power system. One of the most important advantages of this system is the use of hydrogen storage instead of a battery system for energy storage and the conversion of hydrogen into electrical energy with an FC. Unlike other studies, in our study, fossil energy sources such as diesel generators are not included for the stable operation of the system. The system in this study may need hydrogen refueling in unfavorable climatic conditions and the energy storage capacity is limited by the hydrogen fuel tank capacity.

Thermodynamic analysis of a PEM fuel cell power system

The fuel cell power systems are state-of-the-art and are available for space application today. They were designed for the Gemini and Apollo missions and they may became a workhorse for a large number of space vehicles. In selection of fuel-cell type power systems, the mission requirements have to be analyzed, and application of fuel cells versus other type of power systems have to be evaluated. Fuel cells have clear advantages over other power systems for certain type of missions, such as lunar missions and logistic missions, which require stand-by capabilities too. For highest reliability, redundant fuel cell systems have to be considered. After analysis of the mission requirements and complete understanding of the fuel cell capabilities and constraints, the complete power system weight can be established and the necessary space radiators and fuel storage can be calculated.

Fourteen years ago, Georgetown University (GU) perceived the need for a clean, efficient power systems for transportation that could operate on non-petroleum based fuels. The transit bus application was selected to begin system development. GU recognized the range and recharge constraints of a pure battery powered transit bus. A Fuel Cell power system would circumvent these limitations and, with an on board reformer, accommodate liquid fuel for rapid refueling. Feasibility studies for Fuel Cell power systems for transit buses were conducted with the Los Alamos National Laboratory in 1983. Successful results of this investigation resulted in the DOT/DOE Fuel Cell transit bus development program. The first task was to prove that small Fuel Cell power plants were possible. This was achieved with the Phase I development of two 25 kW Phosphoric Acid Fuel Cell (PAFC) brassboard systems. A liquid cooled version was selected for the Phase II activity in which three 30-foot Fuel Cell powered Test Bed Buses (TBBs) were fabricated. The first of these TBBs was delivered in the spring of 1994. All three of these development vehicles are now in Phase III of the program to conduct testing and evaluation, is conducting operational testing of the buses. The test will involve two fuel cell-operated buses; one with a proton exchange fuel cell and the other with a phosphoric acid fuel cell.

Chapter 31 - Power Electronics Applications in Smart Grid

Proton exchange membrane fuel cell power systems (PEM FCPS) represent a promising clean energy technology with applications ranging from transportation to stationary power generation. Honeywell Aerospace is actively developing PEM FCPS for unmanned vehicles (UVs), focusing on the unique requirements of this application. While the engineering principles of PEM FCPS are similar to those for heavy-duty applications, there are critical differences in requirements that must be addressed for UV integration. The three primary requirements are weight reduction, high power density, and overall system efficiency.Reducing the weight of a PEM FCPS involves integrating newer, lighter materials for both the stack and balance-of-plant (BOP) components, as well as combining functionalities to eliminate excess weight. For example, 3D printing connected parts instead of using connectors can significantly reduce weight. Achieving high power density focuses on three key areas of the Membrane Electrode Assembly (MEA): enhancing catalyst kinetics, improving proton conductivity through the membrane, and optimizing water management within the UV system. The main challenge is to increase power density without adding additional weight to the system. This involves balancing the number of cells in the fuel cell stack and optimizing BOP components such as humidifiers and blowers, which may need to be smaller to reduce weight but still provide adequate gas feeds. Overall system efficiency is achieved by optimizing the functionality of every component, particularly within the fuel cell stack. This includes designing flow fields to achieve low pressure drops and ensuring efficient operation of all system components.This abstract presents Honeywell Aerospace’s efforts in designing PEM FCPS to meet these three key requirements, facilitating the adoption of PEM FCPS in the UV market. Figure 1

Power electronic systems have become a key component in the efficient generation, distribution, storage, and use of energy. This increasingly places power electronic systems in harsh environments under elevated stress conditions where, in many cases, their reliable operation is now mission critical. The semiconductor material conventionally used, silicon, possesses limited capability for high temperature applications due to its small bandgap. Power electronic components based on wide bandgap (WBG) semiconductors, such as SiC and GaN, can be operated reliably at higher temperatures. Furthermore, WBG devices have higher breakdown voltages and switching frequencies, rendering them more ideal switches and rectifiers for highefficiency as well as low-volume and low-weight systems. Yet, new packaging concepts are required to make use of the high temperature capability of power electronic systems based on WBG semiconductor devices. In this paper, a summary of the progress in the development and commercialization of wide bandgap power components and power electronic systems is given. The properties of SiC and GaN components are compared to those based on silicon. The shortcomings of conventional power electronic packaging technologies are analyzed, and alternatives introduced and compared. An overview of research is given on Transient Liquid Phase Sintering (TLPS), a promising interconnect technology for the manufacturing of WBG and high temperature power electronic systems. TLPS is a liquid-assisted sintering process during which a low melting temperature constituent melts, surrounds, and diffuses in a high melting temperature constituent. Intermetallic compounds with high melting temperatures are formed by liquid-solid diffusion. Interconnect systems can be processed at low temperatures but are capable of operating at the high melting temperatures of the intermetallic compound. Different process approaches are contrasted and material systems compared. Latest results of research on paste-based low temperature TLPS are presented. The pastes assessed are based on the Cu-Sn and Ni-Sn material systems. It is shown that joints formed by TLPS remain strong up to 600°C and exhibit softening temperatures far higher than conventional interconnect technologies. They show minimum creep and possess very limited voiding. The process does not require an inert or reducing atmosphere or vacuum and is compatible with standard reflow soldering equipment. It shows good wettability to common metallizations such as Cu, Ni, Ag, and ENIG. This attach technology shows the potential to enable reliable operation of wide bandgap power electronic systems under high stress conditions.

Power electronics are used to minimize losses in converting the energy produced by the generator in a wind turbine, and to drive motors that control the pitch and yaw of the wind turbine to ensure maximum power extraction. The power electronic system is based on a series of three-phase pulse width modulated (PWM) power modules consisting of IGBT power switches and associated diodes that are soldered to a ceramic substrate and interconnected with wirebonds. The design of the packaging and cooling of the power electronics is crucial to enhancing the energy efficiency and the reliability of the electronics, which generate heat loads in the hundreds of watts/cm2, and are often placed in harsh and inaccessible offshore environments. Without adequate heat removal, the increase in device temperature will reduce the efficiency of power electronic devices leading to thermal runaway and eventual failure of the entire power electronic system. Furthermore, the increased temperatures can lead to failure of the packaging elements as well. This paper will provide an overview of the fundamental packaging level mechanisms that can cause failures in the power electronic system. These include wirebond and lead fatigue, die attach fatigue, substrate cracking, and lead bonding fatigue.

Modeling and Verification of Dependable Electronic Power System Architecture

The electronic power system can be viewed as a system composed of a set of concurrently interacting subsystems to generate, transmit, and distribute electric power. The complex interaction among sub-systems makes the design of electronic power system complicated. Furthermore, in order to guarantee the safe generation and distribution of electronic power, the fault tolerant mechanisms are incorporated in the system design to satisfy high reliability requirements. As a result, the incorporation makes the design of such system more complicated. We propose a dependable electronic power system architecture, which can provide a generic framework to guide the development of electronic power system to ease the development complexity. In order to provide common idioms and patterns to the system *designers, we formally model the electronic power system architecture by using the PVS formal language. Based on the PVS model of this system architecture, we formally verify the fault tolerant properties of the system architecture by using the PVS theorem prover, which can guarantee that the system architecture can satisfy high reliability requirements. KeywordsSystem Architecture; PVS System; Fault Tolerance; Formal Modeling; Formal Verification.

With the miniaturization of electronic devices, small size but high capacity power supply system appears to be more and more important. A hybrid power source, which consists of a fuel cell (FC) and a rechargeable battery, has the advantages of long lifetime and good load following capabilities. In this paper, we propose the schematic of a hybrid power supply system, that can be integrated on a chip compatible with present CMOS process. Besides, considering the problem of maximizing the on-chip fuel cell's lifetime, we propose a modified dynamic power management (DPM) algorithm for on-chip fuel cell based hybrid power system in wireless sensor node design. Taking the wireless sensor node powered by this hybrid power system as an example, we analyze the improvement of the FC-Bat hybrid power system. The simulation results demonstrate that the on-chip FC-Bat hybrid power system can be used for wireless sensor node under different usage scenarios. Meanwhile, for an on-chip power system with 1cm2 area consumption, the wafer-level battery can power a typical sensor node for only about 5 months, while our on-chip hybrid power system will supply the same sensor node for 2 years steadily.

Passive filter design is traditionally considered to be very important for many power electronic circuits and power systems. It is is very critical in the design of these power electronic circuits and power systems to know how to obtain accurate corner frequencies. It is known that when the load is large, the inductance of an inductor is known to always change. This phenomenon is due to the fact that when the current load is high, the inductance always suffers from saturation or hystersis. It is extremely difficult to estimate the actual value for the nonlinear inductance in large currents because the inductance is nonlinear. The paper investigates the saturation phenomenon for a nonlinear inductance. The describing function method can be used to linearise the nonlinear inductor and then estimate the inductance in large current situations. Hence, the corner frequency for the low-pass filter can also be calculated accurately. It is shown that, when the current is very large, the corner frequency drifts to a larger value in the low-pass filter. The drift value of the corner frequency can be easily calculated by the describing function. Simulation and experimental results verify this phenomenon. However, it should be stressed that the method used in the paper is restricted to low frequencies. The higher frequency effects are neglected throughout the paper.

HFDPS for suitable applications have demonstrated a compact solution for the overall power system while ensuring enhanced system efficiency and reliability. Moreover, adding a communication link for information exchange with limited overhead cost has always been of perpetual interest. However, designing a powerline communication (PLC) network for simultaneous HF power and data transfer for an HFDPS poses various challenges. Firstly, a complex high-order analog filtering circuit is required for coupling/decoupling the power and data signals. Secondly, the use of PLC based technique results in a spectral overlap between the HF power and data signals, which following Shannon’s theorem, reduces the channel capacity for data transmission. In lieu of the above discussion, in this research, a new scheme enabling discrete HF power and data transfer over an HF channel in an HFDPS is outlined and is termed as “Sequential co-transfer scheme.” The proposed scheme is in contrast to conventional PLC, where the power and data co- transmission is simultaneous. Sequential co-transfer avoids data corruption by temporally distributing HF power and data signals over an HF channel and limiting their overlap. In this research, a communication data-transfer architecture mechanism required to realize the sequential co-transfer approach has been outlined. Simple transmitter and receiver circuits, synthesized without the use of any analog-filtering circuitry, are designed, and an asynchronous serial-communication-interface (SCI) protocol is implemented. The sequential HF power and data co-transfer is experimentally achieved and validated on a single-input-single-output (SISO) and a Single-input-multi-output (SIMO) power electronics system. Various applications encompassing packetized power delivery empowered by the sequential co-transfer scheme are envisioned and experimentally verified. Additionally, an in-depth analysis of GaN-based power electronics system required for creating the HF power signals is undertaken, and specific design guidelines for reducing HF noise in the circuit are discussed.

Power electronics, a pivotal field orchestrating electrical energy flow in the modern world, deals with efficient conversion, control, and management of electrical power across diverse applications. While its scope encompasses circuits for energy conversion, its challenges include transporting electrical energy over extended distances. Focusing on electrical‐to‐electrical conversions, the goal is minimal loss for delivering maximum power. The article explores the intricacies of power electronics, presenting key equations, and concepts. The current global power electronics market witnesses growth, driven by demand for energy‐efficient technologies, renewables integration, and the rise of electric vehicles. Future trends indicate continued growth, driven by renewable energy systems, and electric vehicles. Wide bandgap semiconductors, play a crucial role, with ultra‐wide bandgap semiconductors like diamond emerging as potential disruptors. A comparative analysis of semiconductor properties reveals diamond's unique attributes. Despite its challenges, diamond shows promise for power electronic applications, with ongoing research on components like Schottky diodes. Thermal considerations, substrate limitations, and dislocation challenges are discussed, emphasizing the need for advancements to harness the full potential of diamond in power electronics. Finally, some inputs about the importance of overcoming these challenges for the successful integration of diamond in power electronic systems are given.

The Nyquist stability criterion is a graphical technique for determining the stability of a dynamical system. It relates the stability of a closed‐loop system to the open‐loop frequency response and open‐loop pole location. The Nyquist technique is limited to linear, time‐invariant (LTI) systems and has been widely used for designing and analyzing systems with feedback. A practical advantage of the technique is that it can be applied directly to measured frequency response data, due to which the technique is widely used in power electronics systems, where the complexity of a mathematical model would make its widespread use unfeasible. In its first part, this article guides through the fundamentals of the Nyquist stability criterion applied to feedback systems with SISO and MIMO representations. The generalized Nyquist criterion for MIMO systems is then discussed to illustrate its application to the stability assessment of three‐phase power electronics systems. In the second part, four representative cases are introduced to illustrate the applicability of Nyquist criterion–based stability analysis for power electronics systems: a dc‐dc converter, an HVDC system, a three‐phase converter, and a wind farm–HVDC grid integrated system. In the last section of this article, some advanced topics related to large‐scale power electronics systems are introduced. Inherent aspects that are essential for the proper use of these stability techniques are elaborated and discussed in detail, for instance, impedance transformation and modified sequence impedance or the system‐level analysis.