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  4. No.48 November, 2018
Fujikura Technical Review

No.48 November, 2018


Mathematical Models of Flash Charging Method for Supercapacitors

Recently, a lot of mobile equipment has installed "Electrical energy storage devices" that are available in various markets. It is preferable that all kinds of mobile equipment will be used in the condition of high efficiency. However, the idle time relating with moving to charging stations and recharging the devices is inevitable. To save time, supercapacitors, such as "Electrical Double Layer Capacitor" or "Lithium-Ion Capacitor" with huge capacitance, can be employed because of their excellent rapid charging abilities. In order to charge them, a power supply that can provide a supercapacitor with enough electricity is required. Although supercapacitors have such great benefit, it is very difficult to find the power supply whose cost or weight is satisfactory. With this in mind, a simple rapid charging system while using a supercapacitor is strongly advised. Flash Charging Method is a solution that enables charging supercapacitors rapidly. This paper presents Mathematical Models which can implement to calculate the charging time when Flash Charging Method is applied to charge supercapacitors, even though both a required "State of Charge (SOC)" and a required charging time are settled prior to the system design. Results of experiments to demonstrate the models are also presented.

The Built-in Hybrid Device for Automotive Seat

Fujikura has developed and manufactured some advanced sensing devices for a seat belt reminder (SBR) to detect a passenger or an object and those to determine the physique and sitting position of a passenger using a membrane circuit technology. With recent trends in the automotive industry such as the introduction of self-driving systems and electric vehicles (EVs), built-in electronic control systems and sensing devices have been developed rapidly both inside and outside of the car industry. These new products are much more sophisticated than conventional products in ensuring a safe and comfortable driving environment, being expected to be lightweight, space-saving and energy-saving and have multi-functions to enable sensing and monitoring. Currently, we are developing a hybrid device that combines different functions, in addition to the passenger detection device, including seat heating, radio communication of obtained information, and the detection of biological information (breathing, heart rate) of a driver. This paper describes a hybrid device, which consists of an SBR and a seat heating unit using a new circuit board as the platform.

Highly Flexible Heat-resistant Aluminum Cable and Connection Technology for HEV/EV

The hybrid electric vehicle (HEV) and electric vehicle (EV) market is expected to expand in line with the trends of the recent growing interest in environmental protection and tighter environmental regulations in each country. The power systems of these vehicles feature increasingly higher power. To carry high current, the cables of the power supply systems tend to be larger in size and weight and become less flexible. Against this background, there are growing demands for weight reduction and more flexibility of the cables. To respond to these requirements, we have developed a more flexible cable. This cable is also lighter in weight than a conventional copper cable by the use of an aluminum conductor. In addition, we have developed a connection method that replaces the conventional crimp method to secure the connection between the aluminum conductor and the tin-plated copper terminal.

Development for LCP-based Millimeter-wave Devices

Recently, high-speed and huge capacity wireless communication is increasing and there is a limitation in such wireless communication at microwave-frequency band (~30 GHz). Millimeter-wave (mm-Wave) frequency band (~300 GHz) can be available in high-speed and huge capacity wireless communication due to its large bandwidth and its performance is expected to be comparable to that of optical fiber network. Especially, 60 GHz (V-band) and 70/80 GHz (E-band) are expected to be candidates of this application. When configuration of mm-Wave wireless communication systems, substrates inside system are needed to be low loss due to its higher frequency. Liquid crystal polymer (LCP) has lower dielectric properties and similarity of features with those of polyimide which is used in application of flexible printed board so that LCP has advantages both in higher frequency operation and fabrication. In this paper, design and development of several kinds of mm-Wave devices with LCP substrate are described.

High Polarization Purity High Power Laser Diodes

High power laser diode (LD) modules are demanded for sources of fiber laser systems. It is important to use high polarization purity LDs in polarization multiplexing techniques for improving the power of LD modules. We have achieved transverse electric (TE) polarization purity of over 99% in our original self-aligned stripe (SAS)-LDs. The maximum output power of 394 W has been achieved in the LD module by using SAS-LDs for light sources, applied with polarization multiplexing.

5-kW Single-mode Fiber Laser

Single-mode fiber lasers, which have high output power and good beam quality, are demanded in various fields of materials processing. In this report, a 5-kW single-mode fiber laser is demonstrated. Stimulated Raman scattering (SRS), which is a major problem in high power fiber lasers, is well-suppressed in the fabricated laser even with the 20-m-long delivery fiber. Such long delivery fiber is suitable for practical processing fields. In addition, the processing experiment of a pure copper with the laser is carried out. The high processing quality and the tolerance to the back reflection light are confirmed.

Ultra-high-fiber-count Cable with SWR using 200 μm Fibers

Ultra-high density wrapping tube cablesTM (WTCTM) with innovative optical fiber ribbon, which is called "Spider Web RibbonTM" (SWRTM) are reported. This time, as development of ultra-high-count cable, 3456-fiber WTC with SWR using 200 μm fibers was successfully achieved to develop. The developed cable was confirmed that it has satisfactory workability equivalent to WTC using 250 μm fibers and it was fully compliant with the current issue of Telcordia GR-20-CORE. This paper presents the details of these newly developed WTC.

Lensed Connector for Single Mode Fiber

In recent years, data traffic has been rapidly increasing because of development of information and communication technology using the internet. It has been progressed the optical wring between electronic devices to speed up data transmission, but there is concern that the communication degradation will occur due to dust in optical connection portion. In order to solve this concern, we have developed lensed connector for multi mode fiber which indicates good dust immunity and mating workability. On the other hand, data center needs to be further scaled up. It is supposed that optical wiring will be replaced to single mode fiber from multi mode fiber, in order to communicate long-distance between the building. This time, we have developed lensed connector for single mode fiber and confirmed that this connector is practically usable level.