For the design of a horizontal-axis tidal current turbine with adaptive variable-pitch blades, both numerical simulations and physical model experiments were used to study the hydrodynamic performance of symmetrical airfoil blades based on backward swept models. According to the lift–drag ratio of symmetrical airfoils, variable airfoil sections were selected for each part of the blade in the spanwise direction. Then, three kinds of blades were designed by using different swept-back models from wind turbines. A rotation model with a multi-reference frame was employed to conduct a three-dimensional steady numerical simulation of the turbine model based on the CFD method. The axial thrust and energy-capturing efficiency under different tip speed ratios, as well as the corresponding starting torque under different flow rates, were analyzed. The simulation results indicate that model 2 has optimal start-up performance, and model 3 has the largest power coefficient. The thrust coefficient of model 1 is the smallest. In all, model 2 has better comprehensive performance. The experiments of model 2 show that it has suitable hydrodynamic performance to capture bidirectional energy via passively variable pitch. This research provides an important solution for the design and optimization of horizontal-axis turbines to harvest bidirectional tidal current energy.

Tidal energy, as a sustainable and environmentally friendly energy source, has attracted widespread attention in recent years. The technology of blade active pitch control is the key technology to cope with tidal velocity change and improve the stability and efficiency of horizontal-axis tidal generator sets. When solving the problem of speed variation, the core algorithm is the key to ensuring stable operation and improving the efficiency of power generation. When traditional PID is used to manage complex systems, the controller faces the challenge of complex parameter tuning and insufficient robustness. The application of a particle swarm optimization (PSO)–PID controller and fuzzy PID controller in the independent interval system of tidal generator sets is introduced for the first time in this paper. This paper presents a comparative study of unified pitch control and independent pitch control (using electric pitch control) for a three-rotor tidal generator with a rated capacity of 300 kw and a blade radius of 8.5 m. Simulation was carried out on the MATLAB/Simulink (2023a) platform to evaluate the performance of the two controllers under different flow rates and interference conditions. The results show that the PSO-PID controller has significant advantages in reducing overshoot, speeding up response times, and improving power generation efficiency. At the same time, the PSO-PID controller also shows superior performance in pitch angle adjustment frequency and generator output power and realizes timely and effective system stability control.

This article takes a 120 W direct-drive permanent magnet synchronous generator (PMSG) for tidal current energy as the research object, with the aim of starting at low flow velocity, low voltage regulation, and high sealing performance. The research was conducted on the design method of the generator, and the parameter calculation formula is modified based on the structural characteristics of the generator. The design scheme is simulated using the finite element method, and the voltage regulation is optimized using evolutionary algorithm. A prototype was manufactured based on the optimized scheme, and drag experiments and sealing tests were conducted. After that, the generator and impeller were assembled, and water tank drag experiments were conducted. The experimental results verified the reliability of the motor design method in this paper.