The DC-Link capacitors are important components that tend to be one of the weakest part of power converters. Thus it is necessary to monitor the aging parameters of DC-Link capacitors in valuable power electronic systems. This paper proposes a simple yet effective variable electrical network (VEN) condition monitoring method for DC-Link capacitors in three-phase PWM AC/DC/AC power converters. The capacitance(C) and equivalent series resistance (ESR) of DC-Link capacitors are estimated through the designed VEN unit during the discharging process. This VEN method does not need the current sensor or injecting signals into the control loop. The above property is favorable for the hardware and controller design. Besides, the designed monitoring circuit can be an external unit or a built-in unit which offers a flexible solution for electrical devices. When the designed VEN is used as an external unit, neither the hardware design nor the programs in the controller needs to change, which is practical and economic for electrical devices in use. Experiments are carried out in a 55kW AC/DC/AC inverter with different capacitors. The experiment results prove the method to be effective and accurate.

With the fast development of the electrification of vehicles, Electric Vehicle (EV) charging stations will drastically increase in the coming years. In the meantime, the growing demand of charging power, and the intermittent nature of renewable energy are serious challenges for the charging infrastructures and the local grid. In this paper, a real time energy management for the EV charging station equipped with renewable energy generation (RE) and energy storage systems (ESS) is proposed to achieve the maximum consumption of renewable energy through the direct load control of EV charging. A convex optimization problem of energy scheduling is formulated considering the inhomogeneous EV load and real-time price market of grid electricity. The proposed energy management scheme is then evaluated through simulation case studies and results are drawn and discussed.

More-electric aircraft (MEA) has evolved in the recent two decades owing to their superiority in fuel efficiency, noise reduction, and reliability compared to conventional aircraft. The power supply systems, commonly regarded as distributed interactive systems, play a paramount role in MEA, yet are facing critical concerns in terms of their stability. Impedance is a key enabling tool to study the stability of such interactive systems and therefore contributes to better design optimization. Toward this end, this paper presents a comprehensive review of the impedance modeling, stability analysis, and impedance shaping for power supply system in MEA. The three typical power supply system architectures of MEA are introduced and summarized in the first place. Then, existing studies on impedance model are reviewed. Due to the nonlinear time-varying characteristics of the AC system, it needs to be linearized. This paper discusses the characteristics and scope of applications of dq -axis linearization and harmonic linearization methods. Besides, this paper highlights the aspects of the impedance stability analysis including DC and AC stability criterion. The strengths, limitations and application scenarios of each criterion are summarized and discussed. Finally, impedance shaping methods, including structural reshaping, impedance parameter optimization, and system-level control, have also been surveyed and summarized.

The power converters play a key role for the performance of fuel cell power system. The fuel cell output voltage and power depend highly on the random load profile. Thus, a robust design and analysis of the converter can help the online control and optimize the diagnostic method in fuel cell applications. In this paper, a robust control algorithm for DC-DC converter for proton membrane fuel cell (PEMFC) applications is realized through a high-order super-twisting sliding mode method (STSM). The effectiveness of the proposed control methods is verified on a buck-boost converter under various operating conditions including step and varies input disturbances. Moreover, the proposed high-order sliding mode control algorithm can avoid the chattering phenomenon, which commonly happens in power converters when conventional sliding mode control method is deployed. The simulation and experimental results indicate that a stronger robustness can be obtained through the STSM method. The simple architecture of the proposed STSM make it easily to be implemented for the real-time online diagnostic control.