Trapezoidal Current Research Articles

The laminar seabed thermal boundary layer forced by propagating and standing free-surface waves

A mathematical model is developed to investigate seabed heat transfer processes under long-crested ocean waves. The unsteady convection–diffusion equation for water temperature includes terms depending on the velocity field in the laminar boundary layer, analogous to mass transfer near the seabed. Here we consider regular progressive waves and standing waves reflected from a vertical structure, which complicate the convective term in the governing equation. Rectangular and Gaussian distributions of seabed temperature and heat flux are considered. Approximate analytical solutions are derived for uniform and trapezoidal currents, and compared against predictions from a numerical solver of the full equations. The effects of heat source profile, location and strength on heat transfer dynamics in the thermal boundary layer are explained, providing insights into seabed temperature forced convection mechanisms enhanced by free-surface waves.

High-Efficiency Coupling-Insensitive Wireless Power and Information Transmission Based on the Phase-Shifted Control

The trapezoidal current controlled by the phase-shifted modulation is proposed to realize wireless power and information transmission. The fundamental component of the trapezoidal current waveform is used to transfer power, and its harmonic component is selected to transmit information. Fourier decomposition method is conducted to establish the equivalent circuit model of the proposed system. By defining the triangularization rate of the trapezoidal current, quantitative analysis can be gotten to show the relationship of fundamental and harmonic components to different shapes of trapezoidal currents. Compared to the triangular current with the same peak current, the trapezoidal current waveforms can supply higher power. By changing the triangularization rate of the trapezoidal current, a dynamic control method of harmonic components for communication is achieved. Experimental results show that the proposed method can effectively control harmonic components to reduce electromagnetic interference noises, and the impact of communication function on the efficiency of wireless power transfer is extremely weak. Besides, the quasi-decoupling control between load conditions, communication function, and communication speed can be achieved.

Vector Control Specialized for Switched Reluctance Motor Drives

SUMMARYThis paper proposes vector control specialized for a switched reluctance motor (SRM) drive. Because it is a unipolar drive, a sinusoidal current with a dc offset is applied to each circuit instead of the conventional trapezoidal current. The current consists of dc and ac components which can be identified by their generation of a (virtual) rotor flux and rotating stator magnetic field, respectively. Thus, the vector control system can be developed in the same way as conventional ac machines. The proposed technique provides new mathematical models of SRMs on a rotating reference frame and achieves precise and fast torque response and advanced operations such as linear torque‐current control and maximum‐torque‐per‐ampere control. The vector control theory was verified through simulations and experiments.

Vector Control Specialized for Switched Reluctance Motor Drives

This paper proposes vector control specialized for a switched reluctance motor (SRM) drive. Because it is a unipolar drive, a sinusoidal current with a DC offset is applied to each circuit instead of the conventional trapezoidal current. The current consists of DC and AC components which can be identified by their generation of a (virtual) rotor flux and rotating stator magnetic field, respectively. Thus, the vector control system can be developed in the same way as conventional AC machines. The proposed technique provides new mathematical models of SRMs on a rotating reference frame and achieves precise and fast torque response and advanced operations such as linear torque-current control and maximum torque per ampere control. The vector control theory was verified through simulations and experiments.

Research on the Claw Pole Machine with Outer PM Rotor Driven by Trapezoidal Current

The claw pole machine with outer permanent magnet rotor (CPMPM) is a special kind of the claw pole machine. The trapezoidal current drive as a new drive in this motor is a new attempt. On the basis of analyzing its structure, material, characteristics and operating mechanism have proposed a new conduction manner of the trapezoidal current drive；For this machine is not easy to place position sensor, a new function of rotor position-based approach has been put forward to estimate the rotor position in this paper. It has been show that this method can accurately and quickly estimate the rotor position by simulation .It has been prove that this method has good dynamic and static performance.