To regulate the output voltage of inductor–capacitor–capacitor-series ( LCC -S) compensated wireless power transfer (WPT) system, a hybrid control strategy of phase shift modulation (PSM) and a switch-controlled capacitor is presented in this article. In the proposed hybrid control strategy, LCC -S compensated WPT system can realize wide output voltage regulation with zero voltage switching (ZVS), and the reactive current in a resonant tank can be minimized in the whole voltage range. Besides, the current in the primary coil of LCC -S compensated WPT system can be regulated with PSM, which helps to reduce the power loss of the primary coil at light load. Compared with conventional dual-loop hybrid control, the proposed hybrid control can regulate two control variables with one feedback loop simultaneously. To verify the theoretical analysis, a 500-W prototype with 400-V input voltage, 100−250-V output voltage is built. The experimental results show that the inverter can realize ZVS within the whole voltage range and a peak efficiency of 94.7% can be obtained.

In the standalone renewable energy system, multiport converter is more desirable than several single-input converters as it has advantages of simpler circuit, higher efficiency and lower cost. This paper proposes a novel topology synthesis method to derive integrated three-port converters with low cost and compact structure. With the proposed topology synthesis method, integrated three-port converters can be easily developed from conventional single-input single-output (SISO) converters by replacing a switch and a diode with a basic cell including bidirectional power flow. Compared with the SISO converter, the derived integrated three-port converters only need to add the extra switch and diode, which makes they have low cost and compact structure. As an example, topology synthesis based on buck, boost, buck-boost, Cuk, SEPIC, and zeta converters is performed in this paper. The proposed topology synthesis method can also be extended to deduce a series of N-port converters. In order to achieve better understanding of the proposed converters, the integrated three-port SEPIC converter is specifically analyzed, including its operation principle, steady-state performance, small-signal modeling and control system. Finally, experimental verifications have been carried out to illustrate the feasibility and effectiveness of the proposed topology synthesis method.

Multibus dc microgrids, which combine renewable energy sources, energy storage systems, and loads, have voltage stability requirement, which solicits increasing research attention in practice. Potentially complex architectures of the multibus dc microgrids make it difficult to evaluate the stability using the conventional stability criteria. In this article, some constraints related to the conventional stability criteria, such as right-half-plane (RHP) poles or zeros in the subsystems are discussed. Further, an impedance-based stability criterion is proposed in the light of generalized bode plots for multibus dc microgrids. The configuration of the multibus dc microgrid is simplified by adopting generalized voltage source, generalized current source, and two-port model. Then, impedances or admittances for each bus port can be derived, which are helpful for assessing the stability of the system. Using the proposed stability criterion, the stability of each bus port in the multibus dc microgrid can be evaluated separately. The proposed stability method considers the number of RHP pole of the open-loop transfer function for the system so the stability of the system consists of subsystems with RHP pole and zero can be analyzed correctly. Moreover, the intermittent bus converter connected with neighboring dc microgrid can be regarded as an extension unit. Then, the proposed method can be easily extended and is acting as a generalized approach for different configurations, i.e., single-bus dc mirogrid or a cluster of dc microgrids. Experiments are done to validate the effectiveness of the proposed criterion.

A multiport converter with bipolar outputs to integrate renewable energy and energy storage into the bipolar dc bus is the desirable solution due to its high reliability and efficiency. A novel symmetric bipolar outputs full-bridge four-port converter based on phase-shift modulated buck–boost voltage balancer is proposed in this article. The interleaved bidirectional buck/boost circuit with pulsewidth modulation is used as the primary side to achieve the integration of renewable energy and energy storage, whereas the phase-shift modulated buck–boost voltage balancer is derived as a secondary side circuit to generate a symmetrical and common ground bipolar output voltage. Single-stage power conversion, symmetrical bipolar output voltage, approximately decoupled control loop, and soft switching can be realized in the proposed four-port converter. Detailed analysis of the proposed converter is presented, including operation principle, steady-state performance, soft switching performance, and control method. Finally, experimental verifications are carried out to illustrate the feasibility and effectiveness of the proposed topology.

Microgrids relying on cooperative control are supported by communications, which are highly vulnerable to cyberattacks. A significant amount of research is already carried out on the detection and mitigation of cyberattacks to secure the operation of dc microgrids. Although cyberattacks are fully capable of causing cascaded converter outages leading to full/partial system blackouts, disturbing the system stability can also be a viable target by the adversaries, which has been overlooked so far. Hence, this article focuses on addressing the instability caused by stealth cyberattacks, which can easily bypass the well-defined observability tests. In addition, this article also introduces a novel adaptive stabilization method to eliminate the unstable modes due to cyberattacks, which has been designed considering a previously defined cyberattack detection metric as an input. To investigate its feasibility, a detailed model of a stable dc microgrid is first developed. Then, considering stealth cyberattack as a nonlinear element, the describing function-based method is used to investigate system stability under attack conditions. Finally, theoretical analysis, simulation, and experimental results under various scenarios are presented to verify the effectiveness of the proposed stabilization scheme.