International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / RF and IF signals must be down-converted to lower frequencies to allow storage on tape. Pre-Detection converters avoid signal distortion created in later receiver stages, however should not add noise and distortion with their conversion process.

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This thesis examines the development of DC-DC converters that are suitable for Module Integrated Converters, (MICs), in grid interactive photovoltaic (PV) systems, and especially concentrates on the study of the half bridge dual converter, which was previously developed from the conventional half bridge converter. Both hard-switched and soft-switched half bridge dual converters are constructed, which are rated at 88W each and transform a nominal 17.6Vdc input to an output in the range from 340V to 360Vdc. An initial prototype converter operated at 100kHz and is used as a base line device to establish the operational behaviours of the converter. The second hard-switched converter operated at 250kHz and included a coaxial matrix transformer that significantly reduced the power losses related to the transformer leakage inductance. The soft-switched converter operated at 1MHz and is capable of absorbing the parasitic elements into the resonant tank. Extensive theoretical analysis, simulation and experimental results are provided for each converter. All three converters achieved conversion efficiencies around 90%. The progressive increases in the operation frequency, while maintaining the conversion efficiency, will translate into the reduced converter size and weight. Finally different operation modes for the soft-switched converter are established and the techniques for predicting the occurrence of those modes are developed. The analysis of the effects of the transformer winding capacitance also shows that soft switching condition applies for both the primary side mosfets and the output rectifier diodes.

<p>Research shows that flywheels have a significant potential for improving the performance of EV (Electric Vehicle) drivelines. Flywheels can be used as power buffers that even out the energy flow between the primary energy storage device and the EV traction motor. This improves the potential energy density and extends the lifetime of the primary energy storage device of the EV.</p><p>In this degree project a prototype of a flywheel-buffered driveline was constructed. The flywheel chosen was an electric motor/generator constructed at the Division of Electricity at Uppsala University. Lead acid batteries were used as the primary energy storage device in the driveline and the traction motor was a DC-motor.</p><p>Two DC/DC buck converters were designed for the driveline. The first limited the current from the batteries to the flywheel and the second controlled the power from the flywheel to the traction motor. Both converters were controlled by microcontrollers. The current limiter was controlled by a hysteresis controller and the DC-motor power was regulated manually, under the constraint of a maximum current PI-controller. The buck circuits were simulated in MATLAB Simulink prior to their construction.</p><p>The performance of the driveline was satisfactory, despite the poor efficiency of the DC-motor. The results showed that the efficiency of the flywheel and the power converters was relatively high and that the flywheel had excellent power-buffering properties.</p>

Research shows that flywheels have a significant potential for improving the performance of EV (Electric Vehicle) drivelines. Flywheels can be used as power buffers that even out the energy flow between the primary energy storage device and the EV traction motor. This improves the potential energy density and extends the lifetime of the primary energy storage device of the EV. In this degree project a prototype of a flywheel-buffered driveline was constructed. The flywheel chosen was an electric motor/generator constructed at the Division of Electricity at Uppsala University. Lead acid batteries were used as the primary energy storage device in the driveline and the traction motor was a DC-motor. Two DC/DC buck converters were designed for the driveline. The first limited the current from the batteries to the flywheel and the second controlled the power from the flywheel to the traction motor. Both converters were controlled by microcontrollers. The current limiter was controlled by a hysteresis controller and the DC-motor power was regulated manually, under the constraint of a maximum current PI-controller. The buck circuits were simulated in MATLAB Simulink prior to their construction. The performance of the driveline was satisfactory, despite the poor efficiency of the DC-motor. The results showed that the efficiency of the flywheel and the power converters was relatively high and that the flywheel had excellent power-buffering properties.

With today’s technology, digital signal processing plays a major role. It is used widely in many applications. Many applications require high resolution in measured data to achieve a perfect digital processing technology. The key to achieve high resolution in digital processing systems is analog-to-digital converters. In the market, there are many types ADC for different systems. Delta-sigma converters has high resolution and expected speed because it’s special structure. The signal-to-noise-and-distortion (SINAD) and total harmonic distortion (THD) are two important parameters for delta-sigma converters. The paper will describe the theory of parameters and test method.

This thesis aims to investigate an active power factor correction (PFC) circuit and its mathematical model, in order to develop a reliable and efficient simulation platform. By using the PI controller, we can control the inductor current and the output voltage of the boost converter. Finally, we constructed the circuit and analyzed the results to verify that our mathematical model is valid.

All-optical wavelength conversion will be one of the most key technologies in all-optical network. Wavelngth converter using nonlinear effect can resolve wavelength contentions with its high transparency and subcarrier-multiplexed channels in a complex all-optical network model which is more beneficial than O/E/O method. Periodically poled LiNbO3 crystal fiber for wavelength conversion is successfully grown by LHPG method with high-electric-field bias. It does not require conducting the metallic electrode to define domain period. The pitch depends on the frequency of applied external electric field and the growth speed. Domain period of 18.9 £gm for C-band wavelength converter and domain period of 15.45 £gm for tunable blue/green laser are demonstrated in this thesis. Micro-swing during growth is managed to assist poling process. More than 40 nm wavelength range of blue/green laser was generated and 10% internal SHG conversion efficiency was achieved. A simulation shows that maximum tuning range using a graded-period qusai-phase-matching structure can be as large as 33 nm. With the improvement of uniformity, broadband design for cascaded processes, and waveguide structure, superior performance of periodically poled LiNbO3 crystal fiber can be achieved.

The goal of this research is to design a low power, high speed, 10-bit, 250 MHz digital-to-analog converter. For high speed application, the DAC is implemented in thermometer-code based segmented DAC. An optimal switching scheme is used in this design. The switching scheme can compensate the gradient error in thermometer-code DAC arrays.This DAC is implemented in a 0.18£gm 1P6M mixed-signal CMOS process provided by TSMC.