This paper presents a novel linear generator structure of three-phase tubular staggered transverse flux permanent magnet linear generator (TSTF-PMLG) for wave energy conversion. Compared with conventional TF-PMLGs, the new structure has a simpler magnetic flux path, high mechanical strength, low cogging force and more suitable for low-speed direct driven situation. In the primary of TSTF-PMLG, a nonuniform teeth steel sheets structure is used and steel sheets of different phases are in different angel so that the groove can be separated by staggered steel sheets in the plane perpendicular to the direction of movement. By the analytical model, the operation principle of the proposed linear generator is explained. Then through the finite element analysis, the distribution of the main flux and leakage flux, the no-load characteristics and output power of TSTF-PMLG are analyzed in detail. And the influence of the lamination factor on the output characteristics of the TSTF-PMLG is obtained. Subsequently the appropriate design parameters of the TSTF-PMLG are selected. During the TSTF-PMLG processing, the method of mixing silicon steel sheets and fiberglass board is used to limiting the lamination factor. Finially, a prototype of 150 W rated power and 79% rated efficiency is presented. And the experimental results verify the theoretical analysis.

This paper proposes a new division-free generalized sidelobe canceller-based adaptive beamformer and its efficient hardware realization. A discrete cosine transform-based blocking matrix is proposed for uniform linear array to decorrelate the input so as to achieve a faster convergence speed. A new variable step-size least mean squares algorithm for complex input is proposed to further improve the convergence and the steady-state performance of the adaptive beamformer. Moreover, a variable regularization scheme is incorporated to mitigate possible signal cancellation due to possible mismatches in steering vector. Furthermore, a statistical analysis on the mean and mean squares convergence of the algorithm is performed and validated using Monte Carlo simulations. An efficient architecture of the proposed adaptive beamformer is also proposed for its real-time implementation. It employs a novel division-free approach by quantizing the normalization factor into a limited number of levels so that the division can be implemented using canonical signed digits, resulting in multiplier-less realization. The performance of the resultant division-free implementation can achieve similar convergence and steady-state performance as a conventional divider approach while achieving at least 21% less hardware resources and 26.85% higher operating speed in Xilinx Virtex7 (XC7VX330T) field programming gate array for an eight-sensor uniform linear array. Finally, the beam can be stabilized remarkably in only 1 μs at a system clock frequency of 124 MHz.

This paper proposes a new variant of the projection approximation subspace tracking (PAST) algorithm with multiple deflation (MD) and its efficient hardware architecture. It extends the PAST with deflation (PAST-d) algorithm by performing multiple deflations at each step and relies on a recently introduced variable forgetting factor, and variable regularized PAST algorithm to improve the overall convergence rate, steady-state error, and numerical properties. It shares the same simple hardware structure of the PAST-d algorithm in pipeline realization but offering a more flexible tradeoff between complexity and performance. Moreover, methods for estimating the eigenvalues and the dimension of the signal subspace are proposed. Novel simplifications of the proposed variable forgetting factor (VFF) and variable regularization (VR) PAST-MD algorithm are also developed to avoid the expensive cubic root and division operations involved to facilitate its hardware implementation. Moreover, a combined data-regularization update is introduced to avoid the additional QR decomposition (QRD) update associated with the regularization, at the expense of very slight performance degradation. A novel pipelined hardware implementation of the simplified VFF-VR-PAST-MD algorithm based on the QRD and the COordinate Rotation DIgital Computer (CORDIC) is also proposed and implemented in Xilinx field programmable gate array (FPGA). Thanks to the proposed “root- and division- free” schemes, our proposed architecture can achieve around 20.2% higher working speed and save 1.9% LUTs, 1.8% Slice Register, and 22.8% DSPs over conventional implementation of the proposed architecture. Compared to the previous work, which is based on PAST-d algorithm, the proposed QRD-based algorithms offer better performance and a more flexible tradeoff between hardware resources and performance.

Currently, the ocean energy strategy is rapidly developing, and a high proportionate tidal current energy grid connection presents significant obstacles to the planning and secure and stable operation of an island microgrid. For an island microgrid with high proportion tidal current energy access and demand response resources, this research suggests a multiple time scales rolling coordinative dispatching method. An MPPT control based on Q-Learning algorithm is first developed for real-time maximum power tracking of tidal current energy generation after the island microgrid’s topology has been examined. Following that, a multiple time scales rolling coordinative dispatching’s fundamental architecture and implementation method are provided, with equal time intervals coordinated in a step-by-step recursive way. In the example analysis of an island microgrid, we consider the rigid demand load that does not participate in the demand side response, and the ship load and controllable load that participate in the demand side response. On sea islands, ship loads on the long timeframe achieve traffic and energy interaction, and dispatchable loads on the short timescale participate in supply and demand balancing. This is due to the multiple time scales properties of demand response resources. In addition, a multiple time scales rolling coordinative dispatching model for an island microgrid is developed. It includes day-ahead, intraday, and real-time components. Finally, example analysis is used to confirm the dispatching method’s usefulness and advancement, and we conclude that the tidal current energy consumption rate of the island microgrid is increased by 17.08%.