Renewable energy generations have been attracting sustained attentions in academic and industry. Current-fed isolated bidirectional DC/DC converters (CF-IBDCs) are widely adopted in low voltage high current applications such as solar photovoltaic, fuel cell and energy storage. This paper gives an overview and a comprehensive comparative evaluation of CF-IBDCs. The active clamped, dual half-bridge, L-L type dual active bridge, resonant type, naturally clamped and other type topologies of CF-IBDCs are investigated, analyzed and compared regarding their circuit topological structures, characteristics, modulation methods and soft-switching technologies. In addition, component cost models and loss models of converters are deduced and presented. On this basis, quantitative and comprehensive performance comparison of six typical CF-IBDC topologies selected from each type are conducted in terms of costs, losses, weight, volume and power density for the given system specifications and design constraints.

This paper proposes Dual Phase Shift Modulation (DPSM) for active commutated Current-fed Dual Active Bridge (CFDAB) for low voltage high power application to improve the performance of the converter at light loads. The proposed DPSM uses an additional control variable to actively control the peak current in the converter which helps improve the performance as compared to simpler single variable but unregulated peak current control, Phase Shift Modulation (PSM). The control variables are chosen such that the excess current is just enough to achieve ZCS turn-off of the LV devices. In the reverse direction, the converter is a full bridge converter with LC filter. The implementation of the conventional phase shift modulation to the full bridge, popularly known as Phase-Shift Full Bridge (PSFB) is simple but restricted by the ZVS range. The proposed DPSM is implemented in the reverse direction to maintain the ZVS turn on of the HV devices even at very light loads by utilizing the LV devices instead of using them only for synchronous rectification. At higher loads where achieving ZVS is relatively easy, the modulation shifts to conventional phase shift modulation to reduce the circulating current and the associated duty cycle loss. The improvement in the performance is validated experimentally with a 1 kW prototype developed for a 30 % variation in the LV voltage ((42 - 56)V) for both direction of operation. The control of the peak current improved the efficiency by 12 % from the conventional PSM at 10 % load at the highest current (42 V) in the forward operation. In the reverse direction, the ZVS turn-on for the HV devices is achieved even at 6 % load by the proposed modulation at the highest voltage (56 V).

In this paper, an intelligent-agent based energy market management system to integrate energy storage systems into Transactive Energy (TE) markets in distribution systems with microgrids is proposed. Using this platform, two different types of storage market models are proposed to promote local level (within the mirogrid) and communal or global level energy storage systems participation in the intra- and inter- microgrid TE markets. Also, reinforcement learning based smart-bidding strategies for ESSs to participate in the TE markets are pro- posed. The losses caused by each market transaction are then quantified using a current tracing loss allocation method. The overall efficacy of the proposed market management system is demonstrated using IEEE 123 bus distribution system with eight microgrids and energy storage systems. It is proved that the proposed model can effectively reinforce the balance between the supply and demand in the microgrids using the a mix of local and global energy storage systems.

This article proposes a single-phase switched-mode bridgeless ac-dc buck-boost derived converter that can serve as a front-end converter for the on-board electric vehicle (EV) charging application. The bridgeless scheme rules out the orthodox bridge rectifier and the affiliated losses. The proposed converter operates in discontinuous current conduction mode (DCM), thus achieving natural power factor correction for variable ac input. In addition to this, sensing of input voltage and input current is fended off because of DCM operation making the converter reliable, cost-effective, and robust compared with conventional continuous current conduction mode converters. Furthermore, the control becomes simple with the employment of a single sensor and the elimination of the phase-locked loop. The proposed front-end converter is well suited for low-voltage battery chargers ranging between 1.0 and 3.3 kW installed in golf-carts and E-rickshaws. A comprehensive steady-state analysis for one switching cycle and the design equations of the proposed converter are presented. The small-signal model of the proposed converter is presented for the implementation of the closed-loop control. Experimental results from a 1.0-kW concept-proof hardware prototype have been demonstrated, which upholds the converter analysis.

Generally, in wireless inductive power transfer (IPT) system, the power is processed through multiple power transfer stages and this leads to lower efficiency and higher cost of the system. Recent research shows that the use of a direct ac-ac converter in an IPT system compensates these limitations significantly. However, one of the major challenges of the IPT circuit with direct ac-ac converter is to achieve multiple control goals through a single converter. These include load power requirement, maintaining high-quality source current and achieving soft switching of inverter switches, etc. In the existing literatures, the research is more focused on meeting load power requirement and soft switching of inverter switches. The major focus of this paper is to propose, analyze, and control a new IPT power converter topology using current-fed direct ac-ac converter. Compare with existing buck derived, i.e., voltage source ac-ac converter topologies, the proposed topology is boost derived; therefore, active source current waveshaping is easily obtained. The complete control is carried out through two loops, where the outer output current loop ensures load requirements and inner loop maintains the high-quality grid current. The detail of steady-state and dynamic analysis and design procedure of the converter is presented. Experimental results obtained from a 1.2-kW lab-build prototype are included to verify the analysis and proposed control.

This article proposes a novel single-phase bridgeless Cuk-derived power factor corrected (PFC) converter with reduced component count for on-board EV charging application. The unique feature of this proposal is to design and operate the output inductor of the converter in discontinuous current mode for the complete power range to attain PFC naturally at ac mains, thereby not requiring the input voltage and input current sensing, which reduces the converter cost, and improves the power density as well as converter robustness to high-frequency noise. The converter control is very simple in operation and easy in implementation with only a single sensor-based voltage control loop. The semiconductor components voltage stress of the proposed power converter is lower when compared to the traditional Cuk converter. The simulation results from PSIM 11 and experimental results are given by testing a proof-of-concept hardware laboratory prototype to demonstrate the high performance of PFC operation of the proposed converter.