High-frequency-link (HFL) power conversion systems (PCSs) are attracting more and more attentions in academia and industry for high power density, reduced weight, and low noise without compromising efficiency, cost, and reliability. In HFL PCSs, dual-active-bridge (DAB) isolated bidirectional dc-dc converter (IBDC) serves as the core circuit. This paper gives an overview of DAB-IBDC for HFL PCSs. First, the research necessity and development history are introduced. Second, the research subjects about basic characterization, control strategy, soft-switching solution and variant, as well as hardware design and optimization are reviewed and analyzed. On this basis, several typical application schemes of DAB-IBDC for HPL PCSs are presented in a worldwide scope. Finally, design recommendations and future trends are presented. As the core circuit of HFL PCSs, DAB-IBDC has wide prospects. The large-scale practical application of DAB-IBDC for HFL PCSs is expected with the recent advances in solid-state semiconductors, magnetic and capacitive materials, and microelectronic technologies.

Overview of Dual-Active-Bridge Isolated Bidirectional DC–DC Converter for High-Frequency-Link Power-Conversion System

This paper investigates diagnostic techniques for electrical machines with special reference to induction machines and to papers published in the last ten years. A comprehensive list of references is reported and examined, and research activities classified into four main topics: 1) electrical faults; 2) mechanical faults; 3) signal processing for analysis and monitoring; and 4) artificial intelligence and decision-making techniques.

Advances in Diagnostic Techniques for Induction Machines

DC microgrids (MGs) have been gaining a continually increasing interest over the past couple of years both in academia and industry. The advantages of dc distribution when compared to its ac counterpart are well known. The most important ones include higher reliability and efficiency, simpler control and natural interface with renewable energy sources, and electronic loads and energy storage systems. With rapid emergence of these components in modern power systems, the importance of dc in today's society is gradually being brought to a whole new level. A broad class of traditional dc distribution applications, such as traction, telecom, vehicular, and distributed power systems can be classified under dc MG framework and ongoing development, and expansion of the field is largely influenced by concepts used over there. This paper aims first to shed light on the practical design aspects of dc MG technology concerning typical power hardware topologies and their suitability for different emerging smart grid applications. Then, an overview of the state of the art in dc MG protection and grounding is provided. Owing to the fact that there is no zero-current crossing, an arc that appears upon breaking dc current cannot be extinguished naturally, making the protection of dc MGs a challenging problem. In relation with this, a comprehensive overview of protection schemes, which discusses both design of practical protective devices and their integration into overall protection systems, is provided. Closely coupled with protection, conflicting grounding objectives, e.g., minimization of stray current and common-mode voltage, are explained and several practical solutions are presented. Also, standardization efforts for dc systems are addressed. Finally, concluding remarks and important future research directions are pointed out.

/pdf/dc-microgrids-part-ii-a-review-of-power-architectures-69j8nn2rpd.pdf

DC Microgrids—Part II: A Review of Power Architectures, Applications, and Standardization Issues

DC microgrids and distribution systems: An overview

This paper describes a new analytical model for the influence of rolling-element bearing faults on induction motor stator current. Bearing problems are one major cause for drive failures. Their detection is possible by vibration monitoring of characteristic bearing frequencies. As it is possible to detect other machine faults by monitoring the stator current, a great interest exists in applying the same method for bearing fault detection. After a presentation of the existing fault model, a new detailed approach is proposed. It is based on the following two effects of a bearing fault: 1. the introduction of a particular radial rotor movement and 2. load torque variations caused by the bearing fault. The theoretical study results in new expressions for the stator current frequency content. Experimental tests with artificial and realistic bearing damage were conducted by measuring vibration, torque, and stator current. The obtained results by spectral analysis of the measured quantities validate the proposed theoretical approach.

/pdf/models-for-bearing-damage-detection-in-induction-motors-zq7k8exor2.pdf

Models for Bearing Damage Detection in Induction Motors Using Stator Current Monitoring

This paper builds up advancements of optimized model constructions for a single crystalline photovoltaic (PV) panel on a real-time simulator in the view points of improving dynamic model accuracy and boosting computation speed. In addition, several considerations for a power hardware-in-the-loop (PHIL) simulation are provided to electrically emulate the PV panel with power facilities. The effectiveness of the proposed PHIL simulation method developed on Opal RT's RT-Lab Matlab/Simulink based real-time engineering simulator is verified using experimental results of the proposed PHIL simulation system.

Power hardware-in-the-loop simulation of single crystalline photovoltaic panel using real-time simulation techniques

In the previous research, the resonant converter have not integrated the EM noise reduction and the PLC capability in a single power converter. In this paper, the extension of the converter functionality is proposed with the combination of a power line communication (PLC) and the electro-magnetic (EM) noise reduction in the bidirectional halfbridge CLLC resonant converter. The designed converter shows the output voltage regulation, the PLC capability, and the EM noise reduction, simultaneously. This technical fusion using the spread spectrum technique (SST) makes design constraints to implement each functions. Therefore, the design methodology of proposed converter is necessary to implement the triple functions. The performance of the proposed triple functional converter is experimentally verified by using a 20-W prototype converter.

Spread Spectrum Based Power Line Communication and EM Noise Reduction Technique for Bidirectional HB CLLC Resonant Converter

Energy and environmental conservation have prompted interest in high efficiency and low standby power consumption in industrial switch mode power supply (SMPS) applications. However, it is difficult to satisfy both conditions simultaneously due to conflicting design considerations. In this paper, methods of low standby power consumption and high cross regulation are proposed using a novel active clamp control circuit and secondary side post regulator (SSPR) for a flyback converter with multiple output channels. The proposed active clamp control reduces the power consumption of the clamp circuit in standby mode, and the SSPR improves cross regulation performance and minimizes standby energy leakage. The superiority of the proposed converter is verified using theoretical analysis and experimental results on a 110W prototype converter.

Low standby power consumption and high cross regulation of active clamp flyback converter with SSPR

This paper proposes the design considerations of resonant network and transformer magnetics for 500 kHz high switching frequency LLC resonant converter. The high power density can be effectively achieved by adopting high switching frequency which allows small size passive components in the converter. The design methodology of magnetizing inductance is derived for zero voltage switching (ZVS) condition, and the design methodology of the transformer and output capacitance is derived to achieve high power density at high operating frequency. Moreover, the structure of transformer is analyzed to obtain the proper inductance value for high switching operation. To verify the proposed design methodology, simulation and experimental results will be presented including temperature of passive and active components, and power conversion efficiency to evaluate dominant power loss. In addition, the validity of magnetics design will be evaluated with operating waveforms of the prototype converter.

/pdf/design-considerations-of-resonant-network-and-transformer-57iim1w6xm.pdf

Design Considerations of Resonant Network and Transformer Magnetics for High Frequency LLC Resonant Converter

A current-fed dual active bridge (CF-DAB) converter has attracted much attention in battery applications and energy storage systems (ESS) because of their zero-voltage-switching (ZVS) capability and high performance due to the high control degree of freedom. However, conventional switching algorithms cannot reduce the high current in low-side switches under the heavy load condition. It causes high conduction loss which decreases power conversion efficiency. In this paper, a new switching modulation method of the CF-DAB converter for the ESS application is proposed to improve the power conversion efficiency by reducing the conduction loss. The relationship between the pulse width modulation (PWM) and the phase shift modulation (PSM) is investigated and a PWM-plus-PSM modulation method is proposed to reduce the conduction loss. A 1-kW prototype CF-DAB converter is used to verify the effectiveness of the proposed switching modulation method.

Jee-Hoon Jung

Papers

Power hardware-in-the-loop simulation of single crystalline photovoltaic panel using real-time simulation techniques

Spread Spectrum Based Power Line Communication and EM Noise Reduction Technique for Bidirectional HB CLLC Resonant Converter

Low standby power consumption and high cross regulation of active clamp flyback converter with SSPR

Design Considerations of Resonant Network and Transformer Magnetics for High Frequency LLC Resonant Converter

Switching Modulation Method for Current-Fed Dual-Active-Bridge Converter to Improve Power Conversion Efficiency