Kyu-Bum Han

Design and implementation of a high-efficiency on- board battery charger for electric vehicles with frequency control strategy

This paper presents a design and implementation of 3.3 kW on-board battery charger for electric vehicles or plug-in hybrid electric vehicles. A series-loaded resonant dc-dc converter and frequency control are adopted in consideration of efficiency, reliability, volume, cost, and so on. In order to obtain high efficiency and less volume within 6 liters, a prototype of the charger is designed and implemented by using high frequency of 80–130kHz and zero voltage switching method. The experimental result indicates 93% of the maximum efficiency and 5.84 liters in volume of the developed 3.3 kW on-board battery charger. Keywords-fuel cell electric vehicle; FCEV; low frequency current ripple; fuel cell; driving condition

10-bit Driver IC Using 3-bit DAC Embedded Operational Amplifier for Spatial Optical Modulators (SOMs)

A 10-bit driver IC for laser projection full high-definition TV (HDTV) applications using a spatial optical modulator (SOM) has been developed. For high-speed data transfer between the timing controller and driver IC, the driver IC adopts a mini-LVDS interface that operates up to 400 Mbps. To reduce the chip area, a digital-to-analog converter (DAC) structure including a 7-bit resistor-string DAC and a unity-gain buffer, which has a 3-bit linear DAC, is proposed. The area of the proposed DAC is 40% smaller than that of the typical 8-bit resistor-string DAC. The driver IC, which has 546 channels, is fabricated using a 0.35-mum CMOS process, and its area is 21 700 mum times 3 000 mum. The measured INL and DNL of the output voltages are less than 0.13 LSB, and the settling time is 1.93 mus with 40 pF capacitive loads. The output voltage deviation of the driver IC is achieved as 1.3 mV by compensating the nonuniformity among output channels.

A 10b Driver IC for a Spatial Optical Modulator for Full HDTV Applications

A 10b driver IC for laser projection full HDTV applications uses a 7b resistor-string DAC and a unity-gain buffer with a 3b DAC. The driver has 546 output channels, output voltage deviation of less than 1mV, a 200MHz mini-LVDS interface, and a maximum settling time of 2.4 mus for a 1080pixel spatial optical modulator with 40pF capacitive loads. The IC is fabricated in a 0.35 mum CMOS process and the chip area is 21.7 times3.0 mm2

Spatial optical modulator (SOM): high-density diffractive laser projection display

A new type of diffractive spatial optical modulators, named SOM, has been developed by Samsung Electro-Mechanics for laser projection display. It exhibit inherent advantages of fast response time and high-performance light modulation, suitable for high quality embedded laser projection displays. The calculated efficiency and contrast ratio are 75 % and 800:1 respectively in case of 0th order, 67 % and 1000:1 respectively in case of ±1st order. The response time is as fast as 0.7 &mgr;s. Also we get the displacement of 400 nm enough to display full color with single panel in VGA format, as being 10 V driven. Optical module with VGA was successfully demonstrated for its potential applications in mobile laser projection display such as cellular phone, digital still camera and note PC product. Electrical power consumption is less than 2 W, volume is less than 13 cc. Brightness is enough to watch TV and movie in the open air, being variable up to 6 lm. Even if its optimal diagonal image size is 10 inch, image quality does not deteriorate in the range of 5 to 50 inch because of the merit of focus-free. Due to 100 % fill factor, the image is seamless so as to be unpleasant to see the every pixels partition. High speed of response time can make full color display with 24-bit gray scale and cause no scan line artifact, better than any other devices.

A novel diffractive micro-optical modulator for mobile display applications

A diffractive optical modulator has been fabricated based on a micromachining process. Novel properties of its fast response time and dynamics were fully understood and demonstrated for the strong potentials in embedded mobile laser display. Bridged thin film piezo-actuators with so called open mirror diffraction structure has been designed. Optical level package also was achieved to successfully prove its display application qualities. Display circuits and driving logic were developed to finally confirm the single-panel laser display at a 240Hz VGA (640×480). With its efficiency of more than 75% and 13cc volume optical engine with the MEMS-based VGA resolution SOM showed 7 lm brightness at a 1.5W electrical power consumption. Detailed design principle, fabrication, packaging and performances of the invented SOM are described.