High Power Transmission Efficiency Research Articles

Network Analysis and Impedance Matching Methods for Wireless Power Transfer via Coupled Magnetic Resonances

Wireless power transfer (WPT) via coupled magnetic resonances has received much attention owing to its high power transmission efficiency at mid-range distance in recent years. In this paper, a novel network method is used to analyze the WPT system. A two-port network model of the system is built and the ABCD parameters of the model are innovatively used to characterize the system. Then the power transmission efficiency is analyzed at different transmission distance. To improve the power transmission efficiency, an impedance matching method is proposed based on the network analysis of the system. In the end, its feasibility is testified by a case study. The results demonstrate that the maximum power transmission efficiency can be achieved by using the impedance matching method proposed in this paper.

Multi-objective geometrical optimization of full toroidal CVT

The objective of this research is geometrical and kinematical optimization of full-toroidal continuously variable transmission (CVT) in order to achieve high power transmission efficiency and low mass. At first, a dynamic analysis is performed for the system. A computer model is developed to simulate elastohydrodynamic (EHL) contact between disks and roller and consequently, calculate CVT efficiency. The validity of EHL model is investigated by comparing output of this model and experimental data. Geometrical parameters are obtained by means of Particle Swarm Optimization algorithm, while the optimization objective is to maximize CVT efficiency and minimize its mass. The algorithm is run for different values of selected input parameters that are oil temperature, roller tilting angle (speed ratio). Optimization results show that optimized geometrical parameters are approximately constant for various values of input parameters. Also, it is observed that, increasing values of oil temperature and roller tilting angle (in clockwise direction), will decrease power transmission efficiency. An average power transmission efficiency of 86.7% is achieved over a wide range of input parameters, using optimized geometry.

Natural frequency self-tuning energy harvester using a circular Halbach array magnetic disk

A novel natural frequency self-tuning energy harvester is presented, which utilizes the presence of the nonlinearity model and the well-weighted swing disk to maximize the power output and the frequency bandwidth for a wheel rotating at any speed. Kinetic energy harvesters are frequency selective, meaning that they have high power transmission efficiency only when they are excited at their natural frequency. The well-weighted swing disk with nonlinear effects can render the energy harvester more broadband, that is, it has a more steady power generation at various wheel speeds than the ill-weighted swing disk has. We integrate magnets in a novel circular Halbach array and coils into the design to augment the magnetic strength on one side of the array where the coils are placed. Therefore, the gradient of the average magnetic flux density for the circular Halbach array disk is larger than that of the multipolar magnetic disk. The dynamic models with electromechanical couplings have been established and are analyzed. In the experiments, the power output of the prototype at an optimum external resistance was approximately 300–550 µW at about 200–500 rpm and precisely matches the numerical results.

Geometrical optimization of half toroidal continuously variable transmission using particle swarm optimization

The objective of this research is geometrical optimization of half toroidal Continuously Variable Transmission (CVT) in order to achieve high power transmission efficiency. The dynamic analysis of CVT is implemented and contact between the disk and the roller is modeled viaelastohydrodynamic (EHL) lubrication principles. Computer model is created using geometrical, thermal and kinetic parameters to determine the efficiency of CVT. Results are compared by other models to confirm the model validity. Geometrical parameters are obtained by means of Particle Swarm Optimization (PSO) algorithm, while the optimization objective is to maximize the power transmission efficiency. Optimization was conducted over a wide range of selected input parameters that are EHL oil temperature, roller tilting angle and rotational velocity of input disk. Optimization results show that the power transmission efficiency alters with changes of input parameters, while the optimized geometrical parameters are approximately the same. Variations of power transmission efficiency over a wide range of input parameters were calculated for optimized geometry, while the highest value of power transmission efficiency occurs in low value of EHL oil temperatures and input disk rotational velocities. The optimized structure shows average power transmission efficiency equal to 93.4% over a wide range of input parameters.

Integrated Product and Process Design for a Flapping Wing Drive Mechanism

Successful realization of a flapping wing micro-air vehicle (MAV) requires development of a light weight drive mechanism that can convert the continuous rotary motion of the motor into oscillatory flapping motion of the wings. The drive mechanism should have low weight to maximize the payload and battery capacity. It should also have high power transmission efficiency to maximize the operational range and to minimize weight of the motor. In order to make flapping wing MAVs attractive in search, rescue, and recovery efforts, they should be disposable from the cost point of view. Injection molded compliant drive mechanisms are an attractive design option because of manufacturing scalability and reduction in the number of parts. However, realizing compliant drive mechanism using injection molding requires use of multipiece multigate molds. Molding process constraints need to be considered during the design stage to successfully realize the drive mechanism. This paper describes an approach for determining the drive mechanism shape and size that meets both the design and molding requirements. The novel aspects of this work include (1) minimizing the number of mold pieces and (2) the use of sacrificial shape elements to reduce the impact of the weld-lines on the structural performance. The design generated by the approach described in this paper was utilized to realize an operational flapping wing MAV.

Optical label recognition using additional pre-spread coding

A novel scheme of optical label recognition using additional pre-spread coding is proposed. This method can realise both high recognition power and data transmission efficiency. The recognition power of this method is shown by simulation and its optical implementation is presented.

Characteristics of electric power transmission on high-frequency inverter having distributed constant line at load side

An induction heating system aimed at improving the characteristics of high-frequency power supplied from the high-frequency, inverter to the parallel resonant load circuit is proposed, and its transmission efficiency is studied. In this system, high-frequency power can be supplied by lowering the effect of the inductance component accompanied by wiring between the inverter circuit and the resonant load circuit. Impedance matching between the inverter and the resonant circuit and high-efficiency power transmission from the inverter to the load circuit are possible. If a flexible coaxial cable is used as the distributed constant line, it is easy to cope with the case in which comparative distance exists between the inverter part and the heating part or the case in which the heating part is moved. >

Design, manufacture and performance of hybrid reducers with gear and traction elements. (1st report Trial-made of a new speed reducer and power transmission efficiency)

Gear drives have been widely used because of their high power transmission efficiency and the compactness of the gear box. However, gear noise causes trouble in many cases when gear drives are operated at high speed. In order to minimize noise from speed reducers, the authors designed and made a new hybrid speed-reducer with two reduction stages consisting of gear and traction drives. A traction drive with one driving roller and three following rollers was used in the first stage, and a gear drive with three pinion and one gear was used in the second stage. Power transmission efficiency of the trial speed reducer with a total reduction ratio of about 20 was higher than 90%, and running noise from the speed reducer was extremely low.

High Efficiency Power Transmission and Method to Apply Automatic Reactive Power Regulator on Tree Power Transmission Line (with Short Branch)

High Efficiency Power Transmission and Method to Apply Automatic Reactive Power Regulator on Tree Power Transmission Line (with Short Branch)