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Bipolar plates play a role in electron transfer, gas distribution, water management, supporting membrane electrode assembly in the proton exchange membrane fuel cell (PEMFC) and is also a key component to ensure low cost of fuel cell stack. In this paper, bipolar plate materials (metal, graphite and composite materials), functions, advantages and challenges are reviewed. Among them, the composite graphite bipolar plate stands out with its long cycle life and high corrosion resistance, and has received high attention in recent years. The factors related to the conductive network formed by graphite (including the size and shape of filler and the auxiliary filler bridging graphite particles), the composition and curing conditions of polymer, and the influence of the molding process conditions on the properties were discussed in this paper. In the future, the development of composite graphite bipolar plates with excellent comprehensive performance, making existing formulas and forming methods suitable for large-scale production by mastering and optimizing the balance between polymer structure and reaction path on their performance, will greatly enhance the large-scale application of proton exchange membrane fuel cells in more fields.

Ducted fan motors play a crucial role in promoting various applications of flying electric vehicles. In ducted fan motor systems, motor performance affects the speed of the fan, the flow field of the fan affects the thermal field of the motor, and the thermal field influences the performance of the motor. The coupling model between fan static thrust, motor power, and motor temperature rise is established in this paper. After confirming the external dimensions of the motor, three cooling schemes of the motor casing are designed. The casing forms are as follows: model 1 with smooth surface, model 2 with circular fins, and model 3 with longitudinal fins. The optimization work was carried out on the geometric dimensions of two types of fins for model 2 and model 3, and the static thrust and heat transfer performance of the motors were calculated. This study proposes that the ratio of thrust-to-temperature rise is an indicator for future optimization design of ducted fan motors. Model 3 with longitudinal fins has a higher thrust-to-temperature rise ratio. The thrust temperature rise in model 3 has increased by 24.77% compared to model 1. [ABSTRACT FROM AUTHOR]

A continuous variable transmission based on a planetary gear set is used in a full hybrid electrical vehicle (HEV) to integrate the IC engine and two electric machines into the drive train so that the engine can always be at the highest efficiency speed while the vehicle is allowed to run at any desired speeds. However, the two electric machines and a planetary gear box plus two power inverters make the HEV drive train much more complicated and bulky in size. In this paper, the newly invented dual-mechanical-port (DMP) electric machine with multioperational modes and control strategies is presented for HEV use. This single DMP machine realizes full functions of a conventional HEV traction system without the planetary gear set. The novel control algorithms are evaluated by computer simulation and experimental results. Index Terms--Continuous variable transmission (CVT), dual mechanical port (DMP), electric machine, hybrid electrical vehicles (HEVs).

This paper discusses the principle and electrical characteristics of the fuel cell, designs an innovative hybrid power system, and proposes a new dc-dc converter scheme to combine the fuel cell with the storage system. An effective converter scheme for the fuel cell is obtained by analyzing the high efficient topology as well as the phase shifted pulse-width modulation. Through comparing several different control modes of converters, a 75-kW prototype system is constructed, moreover, which steady-state operating characteristics are illustrated and discussed in detail. At last, experimental results are also shown to verify the proposed scheme. Index Terms--DC-DC converter, distributed generation (DG), Fuel Cell.

Lorentz formula is applied here to calculate the electromagnetic forces acting on the stator end windings of a turbogenerator within the first several periods after it is suddenly short circuited, based on the magnetic field computed by the transient quasi-3D method (TQM). The principle of TQM and its essence-processing of winding currents have been disussed. In the example, the forces acting on the stator end windings of a 35MW turbogenerator have been computed, when it is under no-load three phase, no-load line-to-line and no-load line-to-neutral sudden short circuit conditions. Some useful results are obtained.

This paper presents a new method to calculate the 3D electromagnetic field in the end region of a turbo-generator when it is under various sudden short-circuit conditions. This method includes almost all the influential factors to the field calculation such as the eddy currents in the retaining rin etc. and can transform the computation of transient 3D electromagnetic field into a series of quasi-3D problems. One example is given here which shows that the calculated results obtained from this method are consistent with the experimental data. This indicates that the present method is effective.