Auxiliary Power Supply Research Articles

Design and Validation of a 20-kVA, Fully Cryogenic, Two-Level GaN-Based Current Source Inverter for Full Electric Aircrafts

This article presents the design of a cryogenic power electronics converter using wide bandgap (WBG) devices. A 20-kVA two-level current source inverter (2L-CSI) is designed and validated under both room temperature (RT) and cryogenic temperature (CT) of 77 K. CSI has been neglected because of the physically large and heavy dc-link inductor compared to the dc-link capacitor of voltage source inverters (VSIs). However, higher power, together with operation at CT in fully electric aircrafts (FEAs), makes them superior in size, volume, and power quality. The advantage in volume is primarily attributed to the utilization of air-core inductors with superconducting tapes as dc-link storage elements. Therefore, a 2L-CSI with both power stage and associated components at CT is designed and evaluated. As part of converter development, commercially off-the-shelf (COTS) products, including integrated circuits (ICs), isolated auxiliary power supplies, and passive components, were utilized. Numerous laboratory prototypes of cryogenic subsystems were built to screen out the cryocompatible components. Based on components screening, converter subsystems, namely, the gate driver (GD) board and the double-pulse test (DPT) platform, were also developed. Characterization of these subsystems was performed both at RT and CT, where both individual testing and integrated testing were carried out.

Fusion power supply advances by the J-TEXT engineering team

To meet the stringent requirements of the fusion power supply for large-scale fusion devices, the J-TEXT engineering team has carried out key technology research and applications in several important directions of fusion power supply. This article presents the advances made by the J-TEXT engineering team in recent years in the following areas: (1) a high-voltage power supply for an auxiliary heating system; (2) a breakdown protection device for an auxiliary heating power supply; (3) magnetic field compatibility; (4) a high-voltage pulsed power supply for a field-reversed configuration; (5) a large physics experimental facility control system. The research backgrounds, technical progress, test results, applications, summaries and prospects are described in detail in each part. These innovative research results and valuable engineering experience can promote the progress of fusion power supply technology, and also lay a foundation for the development of power supplies with higher parameters in the future.

Fully Self-Powered Inductor-Less Electromagnetic Vibration Energy Harvesting System Using Auxiliary Coils for Hysteresis Current MPPT Control

Utilizing coil inductor of electromagnetic vibration energy harvester (EVEH) to form single stage ac–dc boost converter can make the self-powered milli-power system more compact. However, large output current harmonics of EVEH significantly degraded the output power in such system. This article proposes a new approach of adopting hysteresis current control to realize maximum power point tracking (MPPT) and reduce current harmonics in inductor-less converter by using auxiliary coils. The output characteristics and correlations between multiple coils are firstly studied to verify the feasibility of using auxiliary coil to represent the output of main coil. The optimal winding strategy for main coil and auxiliary coils is revealed for no degradation on maximum output power of main coil. Based upon these, a completely self-powered multicoil EVEH system is designed with auxiliary coils as reference for MPPT controller and as auxiliary power supply in cold-start. Experiments show that the designed prototype can obtain 9.54 mW output power at acceleration of 3 m/s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , with the overall efficiency of 77.6%. To charge a 10 mF supercapacitor from zero to 5 V, an average output power of 7.27 mW can be obtained with an average charging efficiency of 62.4%. In addition, the start-up method adopting auxiliary coil allows the system to cold-start when the output voltage is lower as 0.5 V. The proposed approach has been demonstrated to achieve high overall efficiency in milli-power self-powered EVEH system and also has significant advantages in cost and volume compared with using external devices to obtain reference.

Multi-stage voltage droop compensation based on resonant circuit for unipolar solid-state Marx Generators.

The low-voltage droop of high-voltage pulses is required to provide stable pulsed electric fields in many applications. Increasing the capacitance of energy storage capacitors increases both the size and the cost of the system. In this paper, four compensation stages based on the resonant circuit have been inserted into a 16-stage solid-state Marx generator to compensate for the voltage droop in different conditions. The nearly linear part of the sinusoidal voltage is precisely added to the load during discharging as compensation, and the rectangular pulsed voltage with little droop can be realized. Different numbers of compensation stages and different resonant inductances can compensate the droop to different levels, which means the compensation effect is also adjustable. Moreover, these compensation stages can operate as common stages in Marx generators as long as we open-circuit the resonant circuits. Since the capacitors in resonant compensation stages are also charged in parallel with capacitors in common stages, no auxiliary power supply is required. Simulating and experimental results show that the droop of a 9kV pulse can be ideally compensated over a 500Ω resistive load at various pulse widths. The pulse width should be shorter than the length of the nearly linear part of the sinusoidal voltage.

Supercapacitor Control System Based on Fuzzy PID and Active Equalization Technology

In this paper, a supercapacitor control system is designed to improve the motion performance of small unmanned vehicles. The supercapacitor is used as the auxiliary power supply for the chassis of the unmanned vehicle. When working at low power, the lithium battery supplies power to the chassis and charges the supercapacitor. When climbing or accelerating, the supercapacitor is used to assist the power supply to improve the body’s movement ability. The current and voltage values are collected by high-precision sensors and the system charging control is completed by fuzzy PID. It has a good effect on the test, which significantly improves the motion performance of the unmanned vehicle.

A fault diagnosis method for VRLA battery in data center

The Valve-Regulated Lead–Acid (VRLA) battery is one of the important components of the auxiliary power supply system in the data center. Battery failure in the data center poses a great threat to the smooth operations in the data center. The biggest challenge for the data centers is how to accurately diagnose the faulty battery in real-time in order to ensure the safe operations of the data center. According to the working characteristics of VRLA battery, a battery fault diagnosis algorithm is proposed based on the historical data of battery voltage and internal resistance. The algorithm combines the growth rate of voltage and internal resistance to obtain the indicator that characterizes the performance change of the battery during the working by statistical method. The real-time diagnosis of the faulty battery is estimated by using the Pauta criterion to discriminate the indicator of the battery performance. The effectiveness of the method was verified through a real-time diagnostic test of VRLA battery in a data center. The fault diagnosis method in this paper is compared with the median absolute deviation (MAD) algorithm in the same data set to avoids the missed diagnosis due to voltage value not reaching the fault limits and the false diagnosis caused by power surge or charge–discharge cycle. Compared with the hierarchical clustering based on K-shape algorithm, our algorithm does not need to diagnose the battery in groups. The diagnosis result of the faulty battery is about 7 days faster, and there is no misdiagnosis when multiple batteries fail at the same time. The algorithm can also set the corresponding fault limits for battery fault diagnosis according to the different performance requirements of VRLA battery in data center.

Development of a Resonant Auxiliary Power Supply Control Algorithm and Resonant Destruction Detecting for Railway Vehicles

In this paper, the method and a control algorithm for detecting resonant destruction of a resonant auxiliary power supply for railway vehicle are proposed. It is essential to reduce the weight of the electric equipment attached to the lower part of the railway vehicle because it greatly affects the life of the railway vehicle, such as wheel and bearing. In order to reduce the weight and volume of the auxiliary power supply, in the case of windings, high-speed switching should be performed by lowering the input voltage. Therefore, in this paper, the auxiliary power supply control algorithm using an LLC resonant converter to reduce the weight of auxiliary power supply for railway vehicle is proposed, and the method of detecting resonant destruction due to device failure of a resonant converter is proposed. The proposed algorithm steps down the wire voltage using an input buck converter for high-speed switching, and the inverter input voltage is controlled through the LLC resonant converter. In addition, ZVS (Zero Voltage Switching) is operated to minimize the loss of the resonant converter, and the optimal design of the resonant tank is also proposed. In order to detect resonant destruction, a detection method formulated by analyzing the resonant current peak value for the load capacity is proposed. The algorithm proposed in this paper is verified by simulation and experiment.

Planar Piezoelectric Transformer-Based High Step-Down Voltage-Ratio DC–DC Converter

High step-down voltage-ratio converters are widely used in medium-/high-voltage systems, such as solar power equipment and electric charging station as auxiliary power supplies fed from the dc bus. Traditionally, magnetic transformer-based solutions with high turns ratio are implemented for voltage conversion and galvanic isolation. Instead of utilizing electromagnetic coupling, the high-voltage Rosen-type piezoelectric transformer (PT) provides an alternative solution with electro-mechanical coupling, whose equivalent circuit can be represented by a resonant circuit with an ideal transformer. Moreover, the high-voltage Rosen-type PT features natural mechanisms for high-voltage insulation, high-voltage conversion ratio, and a compact planar form factor, which are all beneficiary for a high step-down auxiliary power supply. This article renders a Rosen-type PT-based high step-down voltage-ratio converter with comprehensive analysis and detailed design procedure. To better understand the operating principle, electrical characteristics of the PT are first analyzed. Effects of input and output compensation components of the PT and their tolerance analysis are subsequently discussed to optimize the performance. After that, topologies of both the input inverter and the output regulation stages are selected. The proposed design is finally validated by a planar prototype with 10-mm height, 5 W full output power, 200 V to 1.5 kV input voltage, and 5 V regulated output voltage.

Performance of Reduced-DC-Source-Based Three-Phase High-Resolution Multilevel Inverter With Optimal Asymmetry

Asymmetrical cascaded bridge multilevel converters use voltage sources of different magnitudes to generate a higher number of levels. However, the availability of sources of different ratings feeding the bridges is a limitation. This article overcomes such a limitation by utilizing the concept of capacitor voltage balancing using the level doubling network (LDN) principle in the space-vector plane. With the use of optimal asymmetry, the presented topology can generate 43 levels at the output line voltage by using only 12 switches per phase. Hence, the most notable attribute of the presented topology is that it does not require isolated auxiliary power supplies to develop such a high-resolution output voltage. LDNs in this topology are self-balanced, and the auxiliary full-bridges require a closed-loop controller to balance their dc bus capacitor voltage. To validate the proposed concept, MATLAB simulations and experimental results are presented in this article.

Integrated Quadruple Output Synchronous Buck Converter for E-Mobility Application

A nonisolated integrated multiple output synchronous buck converter is proposed in this article to cater the auxiliary power supply requirements of e-mobility. The converter provides independently controlled multiple outputs with reduced switch count as compared to conventional separate buck converters as well as conventional synchronous buck converter. The operating principle and working of the proposed converter are discussed in detail for better understanding. As the dynamic behavior of the converter is similar to the conventional buck converter, a simple controller is designed and implemented in this work. The converter is simulated in MATLAB-Simulink. A laboratory prototype of single input–quadruple output (SIQO) converter is developed and operated under closed loop condition to validate and demonstrate its advantages. The prototype is developed by designing two inductors on a single core for increased compactness and reduced cost of the converter. Each output of the converter can be independently controlled by varying the duty ratio of the related switch, thereby eliminating the effective cross regulation problem. The efficiency of the proposed SIQO converter is 93.6%, with four output ports, which is higher than its category of converters reported earlier. A significant improvement in the calculated efficiency is observed with the replacement of conventional switches and diodes of the converter by SiC switches (96.1%).

Reliability Assessment for Auxiliary Power Supply System of a Nuclear Power Plant Based on the Monte Carlo Simulation

Abstract This paper presents a reliability assessment of the Auxiliary Power Supply System (APSS), Class IV of a Nuclear Power Plant (NPP) using the Monte Carlo simulation method. The paper highlights the important role of the APSS in ensuring safe and efficient operation of the plant. The paper provides an introduction to the concept of reliability, emphasizing its significance in the context of NPP. A description of Monte Carlo simulation method is also provided, including its underlying principles and its application to reliability analysis. The paper then describes the role and structure of APSS. A study case is presented to demonstrate the effectiveness of the proposed method in evaluating system reliability. The results of the study suggest that the Monte Carlo simulation method can effectively method to predict the reliability of the APSS.

A portable, auxiliary photovoltaic power system for electric vehicles based on a foldable scissors mechanism

In recent years, countries worldwide have actively advocated electric vehicles for environmental protection. However, restrictions on the driving range and charging have hampered the promotion of electric vehicles. This study proposes a portable, auxiliary photovoltaic power system based on a foldable scissors mechanism for electric vehicles. The system includes a photovoltaic power generation module and an electricity transfer module. The photovoltaic power generation module built based on a foldable scissors mechanism is five times smaller than in its unfolded state, improving its portability in its folded state. The electricity transfer module transfers electricity into the cabin via wireless power transfer units and stores electricity in supercapacitors. Solar simulation experiments were conducted to evaluate the system's performance: maximum output power of 1.736 W is measured when the load is 5 Ω, while maximum wireless power transfer efficiency is up to 57.7% with 10 Ω load. An electric vehicle in Chengdu city was simulated for a case study. The results show that the annual output of a single photovoltaic power system can drive the MINIEV for 423.625 km, indicating that the proposed system would be able to supply power for electric vehicles as an auxiliary power supply system.

Design and Multiobjective Optimization of an Auxiliary Wireless Power Transfer Converter in Medium-Voltage Modular Conversion Systems

This article proposes an optimized design for a wireless power transfer converter serving as an auxiliary power supply in a medium-voltage, high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathrm{d}v/\mathrm{d}t$</tex-math></inline-formula> modular conversion system. A <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLLC-CL</i> circuit topology is implemented to generate a load-independent output voltage with a coupling-coefficient-independent resonant frequency. The output voltage of the circuit can be tuned by changing one pair of resonant <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> parameters, which decouples the circuit gain from the coil design. Essential parameters of coil and magnet are extracted analytically or numerically to avoid time-consuming 3-D finite element analysis simulations for the subsequent optimization. After the design of the circuit and coil, a multiobjective optimization is carried out with objectives being efficiency, isolation capacitance, and insulation rating of the converter. Finally, experiments demonstrate a 48- to 48-V dc–dc converter with 100 W output power, 92.78% efficiency, 2.78 pF isolation capacitance, and 27 kV insulation rating to validate the optimization result.

Power Loss Reduction Control for Modular Multilevel Converters Based on Resistor Controllable Submodule

A bleeding resistor is usually adopted to be parallel with the capacitor in the submodule (SM) to avoid static voltage imbalance caused by auxiliary power supply during start-up process of modular multilevel converters (MMCs). However, the bleeding resistor causes unnecessary power loss during normal operation. In this article, a resistor controllable SM based on a normally- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> silicon carbide (SiC) junction field-effect transistor is proposed to reduce the power loss on bleeding resistor at normal operation of MMCs. The proposed control can not only ensure the static voltage balance during start-up of MMCs, but can also completely eliminate the power loss on bleeding resistor during normal operation of MMCs for high efficiency. In addition, the proposed control can shorten the SM capacitor discharging time at shut-down process. Experimental studies are conducted and the results confirm the effectiveness of the proposed control.

Active-clamped flyback DC-DC converter in an 800V application: Design notes and control aspects

Abstract This paper presents findings for active-clamped flyback (ACF) DC-DC converter 57 W used as an auxiliary power-supply of a wireless inductive-charging system 800 V. Measurements of magnetizing and leakage inductances for three transformers demonstrated how big differences between them could be depending on chosen vendor. Comparison of simulated and measured Bode plots showed that, even when those plots were not matched, one could design a compensator that ensures stable operation. Evaluation of cross-regulation when output with low power (9.62 % of total) was regulated showed that such approach was feasible too. The switching frequency vs output-power and drain-source voltage of switch vs output-power graphs are presented for the first time. Comparison of bandwidth, phase-margin and gain-margin vsinput-power, between the ACF and conventional flyback converter were discussed too. Those quantities were changeable with load and input-voltage as expected. The conventional flyback converter in DCM has higher bandwidth than the ACF which resulted in lower phase- and gain-margins. That showed that it cannot have the same compensator as an ACF.

Reliability analysis of systems with mixed uncertainties based on Bhattacharyya distance and Bayesian network

AbstractThe lack of data due to the high cost of experiments, limited knowledge of system structure, and coupling failure mechanism make it necessary to consider uncertainties when analyzing the reliability of complex systems. This paper provides a comprehensive work for system reliability analysis under consideration of mixed uncertainties. First, Bayesian networks (BNs) are used to model the structure of complex systems. Second, mixed uncertainties are described via a probability box and accurately quantified by the Bhattacharyya distance, which can synthetically represent the mean and variance of two data sets. Then, the importance of components with mixed uncertainties is defined and analyzed. Finally, a comprehensive sensitivity index is proposed for sensitivity analysis and epistemic uncertainty tracing of data sources based on the Bhattacharyya distance. This method is used to analyze the reliability of an auxiliary power supply system of a train and verifies the feasibility and accuracy of the proposed method.

Auxiliary Power Supplies for High-Power Converter Submodules: State of the Art and Future Prospects

Recent developments in medium-voltage (MV) silicon and silicon carbide (SiC) power semiconductor devices are challenging state-of-the-art converter and auxiliary power supply (APS) designs. The APS is an important converter component, which energizes the gate-drive units and, therefore, has an influence on the overall reliability and efficiency of the converter system. There has, however, been comparably little research on how the APS of high-power converter submodules can be realized, in particular, for high-voltage applications. New, or improved, solutions may build on state-of-the-art topologies in the near future, but utilize MV SiC technology in the APS circuit itself to enable improved efficiency, reliability, simplicity, and compactness. Externally-fed APS concepts could provide several further advantages. Their various benefits on converter and system level may enable them to be a competitive solution for future APS concepts. Especially, light-based power supply systems are considered most useful since they offer extreme voltage isolation capability and immunity to electromagnetic interference. This article presents a review of the wide range of solutions for APSs, possible implementation options, and the most important design considerations. The different solutions are evaluated in a qualitative fashion, providing an overview of available APS concepts with regard to the requirements for high-power converter applications.

A Three-Terminal Submodule Based High DC Conversion Ratio System With Self-Balance Feature

The input series output parallel (ISOP) and input parallel output series (IPOS) systems have been extensively researched and applied in academia and industry due to the high dc conversion ratio. Practically, the ISOP and IPOS systems faced challenges, such as relatively immature high-voltage (HV) isolated high-frequency transformer (HFT), high reliability on HV isolated control system, difficulties in the auxiliary power supply (APS), start-up process, and bypass circuit&#x002F;strategy. To overcome the above-mentioned challenges without adding complexities, this article proposes the three-terminal submodule (3TSM) as the fundamental SM for high dc conversion ratio step-up&#x002F;step-down applications. Thanks to the 3TSM, the system is with self-balance feature, HV isolated HFTs are unnecessary, the control system is simplified (no matter in open or closed loop). Besides, commercial APSs can be adopted directly to the SM input capacitors without the unstable &#x201C;runaway&#x201D; phenomenon. A bypass circuit is also proposed to retain the power of APS when the SM is bypassed. A 2SM step-down and step-up prototype, together with a subsequent 10-kV input 1&#x00A0;kV&#x002F;1 kW output converter is built to validate the effectiveness and practical feasibility of the proposed system.

Design and Characterization of PCB Spiral Coils for Inductive Power Transfer in Medium-Voltage Applications

Coil design and operating frequency are key factors impacting the efficiency of the inductive power transfer system. This article presents the modeling of printed circuit board spiral coils, design optimization and analysis on coil geometry, and operating frequency for medium-voltage (MV) applications, such as auxiliary power supplies for MV converters. Analytic model considering the geometric distribution of the magnetic field is proposed to calculate with high accuracy equivalent electrical parameters of coils. For a defined design space and constraints, a large number of coils are designed to determine their performances and select optimal coil geometries. Selected coil designs are prototyped and experimentally verified under design-specific conditions. In addition, further characterization is performed considering variations of several parameters that can be encountered in practice.

Design and Demonstration of a 540 V/28 V SiC-Based Resonant DC–DC Converter for Auxiliary Power Supply in More Electric Aircraft

Efficient and robust power electronic converters are vital to the success of the electrification of aircraft. Especially, low voltage auxiliary converters, which usually supply high current and low voltage loads, are not readily available industrially and need special attention. In terms of energy density and efficiency, LLC converters are among the most commonly used and efficient topologies for automotive and aerospace applications. In the case of aerospace applications, a fault-tolerant topology is highly desirable to reduce the need for redundant components and weight by removing backup systems. To solve this issue, this study introduces a new 2.0 kW LLC-based converter with a reconfigurable fault-tolerant architecture. With the help of a specially designed secondary side, the proposed converter can reconfigure itself so that even if one of the semiconductor switches fails permanently, the converter can still maintain power at nominal voltage levels, ensuring that the aircraft’s vital functionality is preserved. This paper also describes the basic operation principle, component-design aspects, conduction loss reduction techniques, and control system algorithm. Finally, a 2.0 kW experimental prototype is built to verify and demonstrate the operation of the proposed reconfigurable LLC converter.