The fractional-order models have received extensive attention as they could describe the system characteristics of the Boost converter more accurately compared with integer-order models. Due to the singular kernels of traditional definitions that would reduce the modeling accuracy, this paper proposes a Caputo-Fabrizio (C-F) definition-based fractional-order Boost converter model using the small signal modeling method by employing equivalent state variables instead of traditional ones. The proposed model has high accuracy, which is verified by scanning the frequency of the circuit model and comparing it with the mathematical model. Additionally, the influence of fractional order on the system characteristics of the model in the frequency domain is analyzed, providing theoretical support for further studies on fractional-order boost converters with non-singular kernels.

This paper presents, for the first time, a chaos control scheme for the fractional-order Buck converter with Caputo-Fabrizio derivative to suppress the chaos phenomenon. Chaos analysis of the peak current mode fractional-order Buck converter is first carried out by numerical simulation, with a focus on the impact of the fractional order on the system's chaos range. A chaos controller based on a genetic algorithm optimized neural network is then proposed, which combines the neural network algorithm with the parametric resonance perturbation method to optimize the design of control parameters. Finally, circuit simulations in MATLAB show that the proposed method effectively controls the system from a chaotic state to a stable state, demonstrating the effectiveness of the chaos control algorithm used in this paper.

This paper models and analyzes a fractional-order Boost converter with a constant power load (CPL). The transfer function and state equation of the circuit are derived through the small signal linearization method. The boundary conditions for the circuit operating in Continuous Conduction Mode (CCM) are then analyzed. Finally, the correctness of the proposed model is verified by circuit simulation experi-ments, the influence of circuit parameters on CCM boundary conditions is analyzed, and a method for determining the stability of the circuit system is given. The experimental results show that the proposed model can accurately describe the system characteristics of circuits and that using fractional-order components to design the Boost converter with a CPL can effectively expand the stable range of systems.

This study employs the Caputo-Fabrizio fractional derivative to determine the model of fractional-order RC circuits with arbitrary voltage input which can be widely used in a variety of electrical systems. Analog circuit implementation of fractional-order RC circuits defined by Caputo-Fabrizio fractional derivative is presented and verified by comparing with the model proposed in this work. For the purpose of judging whether the fractional-order model defined by the Caputo-Fabrizio derivative is practical, the comparison experiments are carried out. By using Laplace transform, the analytical solutions of fractional-order RC circuits based on the Caputo-Fabrizio derivatives with constant and periodic voltage sources are deduced. Fractional-order model of RC circuits with arbitrary input are also calculated using the convolution formula. The correctness of the derivation of the model using the Caputo-Fabrizio derivative is verified. Through discussing the impedance model of capacitor in frequency domain, the analog realization of fractional capacitor based on the Caputo-Fabrizio derivative is derived. The fractional-orders of the RC circuits models defined by the Caputo and Caputo-Fabrizio fractional derivatives are fitted respectively through repeated charging and discharging experiment data. The fractional-order models based on the Caputo and Caputo-Fabrizio derivatives, and the integer-order model are all compared with the experiment data.

This paper proposed a Z-type modular multilevel converter (Z-MMC) based static synchronous compensator (STATCOM) with capacitor voltage self-balancing ability. With series connection of Z-type submodules, the Z-MMC can generate stepped output voltage waveform with very small harmonic contents. The voltage rating of the Z-MMC can be easily scaled up by adding new ZT-SMs, which makes it suitable for medium/high voltage applications. Different from the traditional modular multilevel converter (MMC) that requires complex voltage balancing control for each capacitor, the capacitor voltages of the Z-MMC are self-balanced. Therefore, the control of the Z-MMC based STATCOM is simplified compared with the MMC based STATCOM. Simulation results confirm the effectiveness of the proposed Z-MMC based STATCOM.

The unmanned aerial vehicles (UAVs) formation needs the frequent data-exchanging of individual's state between units for monitoring and instruction uploading from the ground station, which inevitably occupies huge communication bandwidth. This paper presents the extended Kalman filter (EKF) design based on the event-triggered strategy to get UAVs greatly relieved of the communication burden with guaranteed accuracy. The event-triggered strategy firstly selects only the state measurements containing innovational information for the purpose of filtering. Due to the nonlinearity of UAV system, the EKF is further applied to make full use of the information from the prior event-trigger strategy so as to enhance the performance of estimation. The proposed algorithm is verified on the physical UAVs regarding the estimation quality and communication rate, demonstrating the robust dynamic performance with effectively reduced communication rate.

Due to the advantages of large unit capacity, high efficiency and high reliability, direct-drive permanent magnet synchronous generators (PMSGs) wind turbines (WTs) have been widely used in the offshore wind power generation. The power loop controller aims to maintain the DC-Bus voltage of each PMSG-WT is equal to the others, guaranteeing that multiple WTs can be connected in DC serial parallel collection. In this paper, the DC-Port sequence impedance model of the PMSG-WT is established based on the harmonic linearization method, which takes the outer power loop into consideration. The impedance model is further verified by point-by-point scanning in MATLAB/Simulink. The proposed DC-Port impedance model of the PMSG-WT facilitates the establishment of offshore direct-drive wind farms, and is of great significance for analyzing and improving the system stability.

There is a conflict between the energy transfer efficiency and maximum transferred power in conventional inductive power transfer (IPT) systems, and the energy transfer efficiency is only 50% when maximum power is transferred. To solve this problem, a new topology which is operated at switched-mode is proposed in this paper. The high frequency current of the topology is generated by the free oscillation of the transmitting resonator and a fly-back converter is utilized to inject the energy into the resonator. The energy transfer process is discrete, thus decoupling the load with transmitting (TX) and receiving (RX) coils. The transferred power and energy transfer efficiency are increasing with the coupling monotonously at all coupling region. The operation modes of the topology is analyzed and the experimental results indicate that the topology is effective due to the soft switching operation, low switching frequency and high resonant frequency.

Because of nonlinear and strong coupling features, control system of permanent magnet synchronous motor usually requires high robustness, which can be achieved by fractional-order controller with strong ability against disturbances. A tuning approach based on D-decomposition method and maximum sensitivity is proposed to design fractional-order PIλcontroller for permanent magnet synchronous motor system with current time-delay feedback. Considering the impact of time delay, robust stabilizing region of system is investigated according to D-decomposition method. And maximum sensitivity is applied to the parameters tuning of controller to improve the robustness of control system. Simulations on permanent magnet synchronous motor system with time delay against disturbances are offered to verify the effectiveness of the proposed method.

The DFIG-wind turbine, can create the potential instability to the existent power grid, equivalently presenting itself as a random voltage source with its dynamic impedance, which has the implicit and varying electrical characteristics with the changeable rotor speed. Thus, it inevitably leads to the mutual interaction between DFIG-wind turbines themselves and dynamic custom loads. This paper studies the closed-form impedance analysis of a practical DFIG-wind turbine system. A small-signal model of the DFIG system in the dq-frame is developed with respect to discrete rotor speeds using the impedance-based approach. Moreover, a practical testing method is adopted to facilitate the verification of the impedance modeling.