In the new energy grid connected system, the grid-forming inverter can improve the stability of weak grid or island operation mode, VSG control can enhance system stability and improve dynamic response. but it is difficult to adjust the control parameters in the dynamic process. Due to the self-learning ability of deep reinforcement learning (DRL), especially the advantage of deep deterministic strategy gradient (DDPG) in high-dimensional continuous control of power converter, this paper proposed an adaptive VSG controller based on DDPG, which can realize real-time optimization for the virtual inertia J and virtual damping D. In addition, it can also optimize the PI parameters of PCC voltage loop according to the change of system load, which can reduce the fluctuation of PCC voltage when the system load fluctuates, and improve the response speed and steady-state performance of PCC voltage recovery. The verification results confirm the effectiveness of PCC voltage stability.

The dual active half-bridge (DAHB) converter allows multiple power sources to be interfaced together while maintaining simple control and high efficiency. This paper presents a novel analysis of the DAHB, with a focus on analytical modeling and dc current control. Departing from prior research, a steady-state model is proposed to compute the current wave-forms in the transformer and across the four ports of the converter using a superposition of effects approach. Next, a dc current controller is developed to manage the transformer currents and to achieve the desired currents in the four capacitors. The effectiveness of the proposed model and control algorithm is tested using both simulations and experimental data.

In recent years the implementation of wireless power systems has increased due to improvements in technology and efficiency. Some advantages of wireless power transfer technology are reliability, safety, and convenience of use. One of the challenges with these systems is output regulation, as there are no physical wires to access it. Further complications are the variability of coil coupling and output power in the case of chargers. Firstly, this paper has summarized some of the main techniques for controlling the output of inductive power technology. Moreover, a predictive free communication control from the primary is proposed. It is aimed at charging systems with constant but unknown coupling, using a small drone charger as a reference. This control allows the secondary side to be simplified and acts faster than a control loop at the output due to the predictive measurement and feedforward operation. The simulation results for an output voltage of 5 V show an error of less than 3 % for a coupling range of 0.25 to 0.5.

This paper discusses the power converter interface between the 400 VDC DC microgrid and the European threephase grid (400 VLL). Therefore, power bidirectional step-down topologies are considered in this paper. Among the various topologies, three single-stage non-isolated topologies are compared in terms of semiconductor losses, magnetic component size and heat sink size. These topologies are the seven-switch buck converter, the SWISS converter and the Y-converter. The comparative evaluation is conducted for a 10-kW converter targeting residential or small commercial applications.

Isolated multi-port converters show the merits of hosting several sources and loads with different voltage and power ratings, allowing power routing among multiple ports with high power density. However, many degrees of freedom are available for modulation, and exploiting them for optimal converter operation is challenging. This paper proposes an artificial neural network (ANN) approach that minimizes the rms ports currents of a triple active bridge (TAB) converter for the entire range of operation. The ANN is trained to determine the optimum duty-cycles for total true rms current minimization. The effectiveness of the ANN implementation is shown by considering an experimental TAB converter prototype rated 5kW.

The output impedances of inverters can be reshaped to improve current sharing accuracy in islanded microgrids. This article proposes a decentralized current sharing strategy based on iterative virtual impedance regulation (IVIR). The whole IVIR process is decomposed into several continuous iterations. During each iteration, three stages are involved. In the first stage, a virtual impedance increment is generated with the integral of the inverter uniform output currents. Then, an impedance compensation is introduced to restore the voltage magnitude in the second stage. In the third stage, the current sharing error is evaluated. Based on this iterative regulation, the impedance mismatches are eliminated with small virtual impedances, all the balanced, unbalanced, and harmonic current components are distributed accurately, and good voltage quality maintains. The proposed control strategy requires neither communication nor grid impedance knowledge. Simulation and experimental results are presented to verify the effectiveness of the proposed strategy.

In this paper, two-level and three-level modules for a three-phase multi-port converter (MPC) are evaluated and compared regarding the number of components and semiconductor losses. The MPC connects two medium-voltage ac (MVAC) microgrids to a common storage unit. The two-level MPC unit comprises a full-bridge converter for the ac-side and an isolated triple active bridge (TAB) dc-dc converter connecting the three ports. The full-bridge is replaced by a three-level neutral point clamped converter in the three-level solution. The comparative study was performed using PLECS simulation.

Passive cell balancing is the most used technique to compensate the voltage mismatch in series-connected Li-Ion batteries, due to cost and simplicity. Active cell balancing is recently gaining more attention as it improves the battery capacity when the battery is ageing and, thus, lifetime when this is determined by the residual capacitance as in the electric transportation sector. This paper proposes a circuit configuration that can perform the active cell balancing using a multi-active half-bridge converter (MAHB) and a multi-winding transformer. The proposed solution has high flexibility due to different operating modes and a relatively simple circuit configuration. Depending on the State Of Charge (SOC) of each cell, the bidirectional power flows can be controlled between two arbitrary cells or between the entire string and a specific cell. A theoretical analysis is firstly carried out in order to understand the behavior of the circuit. Simulations and experimental results on a four Li-Ion cell prototype verify the validity of the proposed solution.

The paper analyzes and reports the performance of two isolated, bidirectional dc-dc converter topologies, namely, the dual active-bridge converter (DAB) and the interleaved boost with coupled inductors (IBCI). A modulation principle applicable to both the topologies is also proposed and reported. The considered topologies find natural application in smart dc power systems integrating renewables and energy storage systems, for which loss minimization is crucial. It is shown that the proposed modulation scheme, on the basis of simple converters modeling, allows to ease zero-voltage switching (ZVS) operation of the switching devices, giving significant efficiency improvements. The reported results show that ZVS operation is easier to achieve for the IBCI, which is associated to better overall efficiencies. Experimental results under equivalent modeling accuracies and comparable hardware platforms are reported considering prototypes rated for 1.5 kW.

This paper studies the integration of the two-level split-source inverter (SSI) concept into the three-level diode-clamped inverter configuration. The proposed three-level diode-clamped-based SSI (3L-DC-SSI) uses two isolated dc sources, two inductors, two capacitors, and six input diodes with the three-level diode-clamped bridge. This topology introduces lower current stresses of the switches compared to the three-level flying capacitors-based SSI (3L-FC-SSI). Moreover, the 3L-DC-SSI has the ability to be operated from two unequal isolated dc sources, where its modulation and mathematical derivation in this case is discussed as well. On the other hand, this topology has some limitations in terms of the higher voltage stresses and the low frequency component in the input current and the inverter voltage. The 3L-DC-SSI is analyzed in this paper using the standard space vector modulation scheme, where simulation results of a 30 kVA system are introduced.

Grid-connected power conversion systems for renewable energy sources must fulfill several requirements, including high efficiency, reduced cost and complexity, and, quite often, also boost capabilities from the dc sources to the ac power grid. For such applications, single-stage power converters with boost capabilities offer some potential advantages. Among several proposed options, split-source inverter (SSI) has been recently investigated. This paper proposes a decoupled control scheme for the SSIs, where the common mode term of the ac modulation signals is used to control the dc input current. Thus, the dc input current and ac output current can be controlled independently. The proposed solution is simulated using MATLAB/Simulink models and verified with experimental results.

Single-stage DC-AC power converters are recently gaining higher popularity due to their features in terms of size, cost, weight, and complexity of the whole system. Different topologies exist, where the Z-source inverter, the buck-boost voltage source inverter, and the Y-source inverter are the common topologies. This paper proposes another single-stage DC-AC power converter, called the split-source inverter. The proposed topology has some merits over the other topologies, the main being the possibility to use the same modulation schemes of the conventional voltage source inverter without any modification. The operation of the split-source inverter is studied and analyzed in this paper then verified using MATLAB/Simulink models. Finally a small-scale prototype is used to confirm the functionality of the proposed idea.

Single-stage DC-AC power converters are gaining higher popularity due to their merits compared to the conventional two-stage DC-AC conversion systems. One of these converters is the buck-boost voltage source inverter. This converter has some merits over the other single stage DC-AC power converters in terms of passive component-count, overall gain ratio, and voltage stresses. This paper studies the possibility of using the buck-boost voltage source inverter as a bidirectional power converter, where it proposes a modification that should be applied to the conventional modulation schemes of the so-called buck-boost voltage source inverter to support the reverse power flow capability in it. The conventional and the proposed modulation schemes are simulated in a grid-connected mode using MATLAB/Simulink models, where the P+Resonant controller in the stationary reference frame is used. Finally a small scale prototype is used to verify the proposed modification.

Low-voltage microgrids can be seen as the basic tiles of the smart grid patchwork, owing to their capability to efficiently manage their distributed energy resources in aggregate form. They can support the grid in terms of demand response, power quality, ride through capability, etc., and at the same time they can ensure electrical continuity to the loads even in case of grid failure. This paper describes a simple and effective approach to manage microgrids by synergistic control of the power electronic interfaces acting therein, i.e., the Utility Interface (UI) installed at the point of common coupling with the utility, and the Energy Gateways (EGs) interfacing distributed generation units and energy storage devices with the distribution grid. In our approach the UI acts as control master for the microgrid: in grid-connected operation, the UI dispatches active and reactive power references to the EGs so as to improve energy efficiency and voltage; in islanded operation, the UI performs as grid-forming voltage source and assures the power balance by exploiting any local energy storage. The paper describes the theoretical background of the proposed control approach and demonstrates the system performance by MATLAB/Simulink simulation.

This paper proposes a detailed step-by-step design procedure for the input and output EMI filter of a matrix converter (MC) driving a 30 kW permanent magnet synchronous motor. The procedure involves modeling the EMI source and conduction path in the frequency domain, the design of the passive components, and the estimation of the EMI filter weight and volume. Finally, a weight comparison between the MC and alternative two- and three-level back-to-back converters is presented showing the significant advantage offered by the MC in this regard; namely a 30 % and 50 % lower weight than its three-and two-level counterparts. Time and frequency domain simulations are used for verification purposes.

Cooperative control of distributed energy resources can improve dramatically the operation of residential microgrids, in terms of voltage stability, distribution efficiency and power quality, while allowing cost-effective management and sharing of energy resources among prosumers (electric customers which produce and consume energy). This paper describes an optimum control technique which provides the above features and can be implemented in low-voltage microgrids by making use of a distributed ICT infrastructure of limited complexity and narrowband communication capability.