Yushi Kamiya

Deterioration in fuel cell performance resulting from hydrogen fuel containing impurities: poisoning effects by CO, CH4, HCHO and HCOOH

This paper covers our investigation into a decline in fuel cell (FC) performance resulting from hydrogen fuel containing impurities. This is a serious problem in case of adopting the methanol or gasoline reforming approach as a means of supplying fuel to FCs. The results are summarized as follows: (1) Components of the gas generated by the reformer adopting the steam reforming and auto thermal reforming approach were predicted and specific components and concentrations were identified; (2) Various experiments and analyses were conducted to determine the adverse effect of CO, CH4, HCHO and HCOOH poisoning on the performance of FC.

3D eddy current analysis by the finite element method using double nodes technique

There are several difficulties in calculating eddy currents in plates with thin slits by the finite element method (FEM). Under the influence of flat finite elements at slits, the accuracy of analysis decreases and the computation time increases. Using the A-/spl phi/ method, we propose a novel technique, which overcomes those defects. The feature of the method is to adopt double nodes for the electric scalar potential /spl phi/ at slits, but not to the magnetic vector potential A. Adopting this technique, slits are equivalent to current barriers that have infinitesimal width. Some numerical results, which show the validity of the proposed method, are also presented. We analyze the magnetic fields of a double-sided linear induction motor with slits in a secondary plate, as a suitable model for proving the validity of the proposed method.

Development of a non-contact rapid charging inductive power supply system for electric-driven vehicles

Non-contact rapid charging inductive power supply (IPS) system has been developed and tested as a charger for electric-driven vehicles (EdV). By using the developed system, EdV charging can be carried out safely, easily, and in a short period. Optimizing the track and pick up design of the IPS based on finite-element electromagnetic field analyses achieved significant improvements in efficiency (92%), weight (35kg), thickness (33mm), and air gap length (100mm) during 30kW power transmissions.

Development and performance evaluation of a non-contact rapid charging inductive power supply system for electric micro-bus

A non-contact rapid charging inductive power supply (IPS) system has been developed and tested as a charger for electric-driven vehicles (EdV). By using this system, EdV charging can be carried out safely, easily, and in a short period. Optimizing the track and pick up design of the IPS based on finite-element electromagnetic field analyses achieved significant improvements in efficiency (92%), weight (35kg), thickness (33mm), and air gap length (100mm) during 30kW power transmission. Testing on public roads of an electric-micro bus equipped with the IPS is also detailed.

A novel block feeding method in the single-sided linear induction motor with a short secondary member

In this paper, the authors propose a novel block feeding method for use in linear induction motors. The proposed method involves shifting of the excited section at every coil. Using the proposed method, the excited-section length can be shortened greatly compared with that in the ordinary method shifting at every block section. Thus, the power consumption becomes lower, improving efficiency. In addition, by short-circuiting the coils at both ends of the excited section during shifting, continuous power supply becomes possible, and thus electric transient phenomena are reduced. They confirm the validity of the method by finite element analysis and experiments.

Development and performance evaluation of lithium iron phosphate battery with superior rapid charging performance — Second report: Evaluation of battery capacity loss characteristics

A lithium iron phosphate battery has superior rapid charging performance and is suitable for electric vehicles designed to be charged frequently and driven short distances between charges. This paper describes the results of testing conducted to evaluate the capacity loss characteristics of a newly developed lithium iron phosphate battery. These results confirmed that, in the assumed use temperature range of the battery, the degree of storage capacity loss (referred to below as “calendar capacity loss”) over 120 days was approximately 4% and the degree of capacity loss on cycle test over 500 cycles was approximately 6%.

Characteristics analysis of linear induction motor with two types of secondary structures based on electromagnetic field and electric circuit analysis

In this study, we attempt to analyze characteristics of single-sided Linear Induction Motor with a short primary member and a complicated secondary structure, which consists of solid-plate conductor section and a winding one. For this purpose, electromagnetic field analysis by 3-D FEM is combined with electric circuit analysis and motion equation. Here, electric circuit analysis involves the primary and secondary windings. Focusing on the distributions of secondary induced current and thrust force, we discuss various transient phenomena that develop at the boundary between different secondary structures. Finally, to suppress the aggravation of characteristic caused by the secondary structural transition, we improve the boundary.

Analysis of degradation mechanism of lithium iron phosphate battery

The degradation mechanisms of lithium iron phosphate battery have been analyzed with 150 day calendar capacity loss tests and 3,000 cycle capacity loss tests to identify the operation method to maximize the battery life for electric vehicles. Both test results indicated that capacity loss increased under higher temperature and SOC conditions. And also, large increase of internal resistance on the high temperature and high SOC conditions was confirmed by AC impedance tests. The real cycle capacity loss characteristic was derived by subtracting the capacity decrease due to calendar capacity loss during the cycle test from the overall capacity loss characteristic obtained from the cycle test. As a result, it is found that the real capacity loss contains not only structural disorders of electrode but also degradation factors due to the chemical reactions. Characteristics of degradation were quantified with equations based on the chemical kinetics. With this degradation prediction, an operation method was proposed that is compatible with the long life of batteries and the safety driving of a vehicle. As a result, with optimizing the SOC range used in the operation as follows: 30-10% in the warm seasons, 45-25% in the cold seasons, it was found that batteries can last 4 times longer than it used with high SOC range in every season.

Dynamic charactfristics of the synchronous motor applying plural sub-magnets scheme to the rotor

This paper treats the optimization of rotor construction in the permanent magnet synchronous motor (PMSM). While the field system of PMSM has generally one magnet per pole, we replace the magnet with plural sub-magnets. The dimensions of each sub-magnet are determined by the concept of pulse width modulation (PWM). By adopting the proposed rotor construction, we can not only reduce the spare harmonics of the air-gap field but also provide space for damper winding around the direct-axis. From the investigation by hybrid FE-BE (coupled finite element and boundary element) method combined with both electric circuit and motion equation, we verify that the proposed construction is effective for practical use in view of both the harmonics reduction and the damping effects.

Development and Performance Evaluation of an Electric Mini Bus Equipped with an Inductive Charging System

The limited range, high cost and long charging time of electric vehicles continue to stand in the way of their widespread adoption. In response to this, our research group has created the “Waseda Electric mini Bus (WEB)” series of vehicles based on a short range, frequent charging concept that minimises the weight and cost of batteries compared to other electric vehicles. This paper reports on the design, construction and performance evaluation of the new “Waseda advanced Electric mini Bus 3 (WEB-3)”, which is larger than previous vehicles and utilises an improved inductive power supply (IPS) for non-contact rapid charging. A diesel bus was converted to an EV, and the engine, flywheel and clutch were removed, reducing the vehicle’s rotating weight by 80 %. A new inductive charging system was designed and fabricated, allowing non-contact rapid charging from a transmission coil in the road surface over a longer air gap of 140 mm, at 92 % efficiency.The finished WEB-3 was tested on public roads in Honjo and Kumagaya cities, Saitama prefecture, Japan. An effective reduction in CO2 emissions of 60 % over the original diesel bus was achieved.