Over the past few years, the use of LEDs within the automotive and avionic industries has increased due to their high efficiency, durability and wide range of light brightness. As the use of LEDs within these industries grows, a need for reliable, high performance drivers becomes more relevant. Companies are implementing LEDs for applications involving adaptive lighting or simple dimming features. This thesis shows implementation of various non-isolated analog converters integrated with digital dimmers to achieve these adaptive lighting systems. Adaptive lighting systems involve reading an input from an external source (brake pedal or steering wheel) and changing the brightness and/or pattern of the brake/headlights to convey more information to the driver and their surroundings. The analog converters will implement Linear Technology’s LED driver IC’s, while the digital dimmers comprise of microcontrollers and discrete components. The design, simulation, and hardware verification will showcase the abilities of these analog converters. Results will demonstrate the proposed applications for both adaptive front and brake lighting.

DC-DC power converters play an important role in powering telecom and computing systems. With the speed improvement and cost reduction of digital control, digital controller is becoming a trend for DC-DC converters in addition to existed digital monitoring and management technology. In this thesis, digital control is investigated for DC-DC converters applications. To deeply understand the whole control systems, DC-DC converter models are investigated based on averaged state-space modeling. Considering half-bridge isolated DC-DC converter with a current doublers rectifier has advantages over other topologies especially in the application of low-voltage and high-current DC-DC converters, the thesis take it as an example for digital control modeling and implementation. In Chapter 2, unified steady-state DC models and small-signal models are developed for both symmetric and asymmetric controlled half-bridge DC-DC converters. Based on the models, digital controller design is implemented. In Chapter 3, digital modeling platforms are established based on Matlab, Digital PID design and corresponding simulation results are provided. Also some critical issues and practical requirements are discussed. In Chapter 4, a DSP-based digital controller is implemented with the TI's DSP chip TMS320F2812. Related implementation methods and technologies are discussed. Finally the experimental results of a DSP-based close-loop of HB converter are provided and analyzed in Chapter 5, and thesis conclusions are given in Chapter 6.

This work is focused on exploring advanced solutions for space power management and distribution (PMAD) systems. As spacecraft power requirements continue to increase, paralleled by the pressures for reducing cost and overall system weight, power electronics engineers will continue to face major redesigns of the space power systems in order to meet such challenges. Front-end PMAD systems, used to interface the solar sources and battery backup to the distribution bus, need to be designed with increased efficiency, reliability, and power density. A new family of integrated single-stage power converter structures is introduced here. This family allows the interface and control of multiple power sources and storage devices in order to optimize utilization of available resources. Employing single-stage power topologies, these converters control power flow efficiently and cost-effectively. This is achieved by modifying the operation and control strategies of isolated soft-switched half-bridge and full-bridge converters--two of the most popular two-port converter topologies. These topologies are reconfigured and utilized to realize three power processing paths. These paths simultaneously utilize the power devices, allowing increased functionality while promising reduced losses and enhanced power densities. Each of the proposed topologies is capable of performing simultaneous control of two of its three ports. Control objectives include battery or ultra-capacitor charge regulation, solar array maximum power point tracking (MPPT), and/or bus voltage regulation. Another advantage of the proposed power structure is that current engineering design concepts can be used to optimize the new topologies in a fashion similar to the mother topologies. This includes component selection and magnetic design procedures, as well as achieving soft-switching for increased efficiency at higher switching frequencies. Galvanic isolation of the load port through high-frequency transformers provides design flexibility for high step-up/step-down conversion ratios. It further allows the converters to be used as power electronics building blocks (PEBB) with outputs connected in different series/parallel combinations to meet different load requirements. Utilizing such converters promises significant savings in size, weight, and costs of the power management system as well as the devices it manages. Chapter 1 of this dissertation provides an introduction to the requirements, challenges, and trends of space PMAD. A review of existing multi-port converter technologies and digital control techniques is given in Chapter 2. Chapter 3 discusses different PMAD system architectures. It outlines the basic concepts used for PMAD integration and discusses the potential for improvement. Chapters 4 and 5 present and discuss the operation and characteristics of three different integrated multi-port converters. Chapter 6 presents improved methods for practical digital control of switching converters, which are especially useful in complex multi-objective controllers used for PMAD. This is followed by conclusions and suggested future work.

In this Dissertation, which concentrates on discrete modeling for control purposes of DC/DC converters and simulation through symbolic techniques. A Unified Discrete State-Space Model for power converters in CCM is presented. Two main approaches to arriving at the discrete model are used. The first approach involves an impulse function approximation of the duty cycle modulation of the converter switches, and this approach results in a small signal discrete model. The Second approach is direct and does not involve any approximation of the modulation, this approach yields both a large signal nonlinear discrete model and a linear small signal model. Harmonic analysis of the converter's states at steady-state is done for steady-state waveform acquisition, which increases the accuracy of the model especially for finding the control to inductor current frequency response. Also the harmonic Analysis technique is used to both obtain the response of the converter to a load transient and to finding the optimal duty cycle response that minimizes the disturbance. Finally the Discrete model is verified for the Half-Bridge DC/DC topology for its three main control schemes (Asymmetric, Symmetric, DCS). A GUI platform in MATLAB is presented as a wrapper that utilizes the models and analysis presented in this thesis. Symbolic simulation techniques are developed in general manner for linear piecewise circuits and then through State-Space formalism specialized for DC/DC converters. A general symbolic solver programmed in JAVA that implements said techniques is presented.

This paper presents the development and study of multiple-input single-output converter (MISO) for the DC House project that utilizes a controller to maximize the overall converter’s efficiency. The premise of this thesis is to create uneven load current sharing between the converters at different loading conditions in order to maximize the efficiency of the overall MISO converter. The goal is to find a proper ratio of current from each converter to the total load current of the MISO system to achieve the greatest efficiency. The Arduino microcontroller is implemented to achieve this goal. The design and operation of the MISO converter with the proposed controller will be explained in this paper. The design and operation of the converter was tested and verified through simulation in LTSpice in addition to hardware implementation. Different ratios of current from each converter were used to fully test the MISO converter. For the 5A and 6A load current, the maximum efficiencies were reached with the 70% / 30% ratio case, with efficiencies of 94.91% and 95.07%, respectively. For 7A load current, the maximum efficiency was reached with the 60% / 40% ratio case, with an efficiency of 94.59%. The results were then compared with those obtained from the equal current sharing cases. For the cases tested, the efficiency of the unequal current sharing outperforms that obtained from the equal current sharing method.

This report details the design and implementation of a switching DC-DC converter for use in the Energy Harvesting From Exercise Machines (EHFEM) project. It uses a four-switch, buck-boost topology to regulate the wide, 5-60 V output of an elliptical machine to 36 V, suitable as input for a microinverter to reclaim the energy for the electrical grid. Successful implementation reduces heat emissions from electrical energy originally wasted as heat, and facilitates a financial and environmental benefit from reduced net energy consumption.

This thesis entails the stability analysis of the Multiple Input Single Output (MISO) DC-DC converter developed for the DC House Project at Cal Poly. A frequency domain control system model of the MISO converter was designed and constructed using MATLAB Simulink. Transfer functions were derived and modeled for each stage of the converter to best fit the converter circuit system used in the original MISO circuit. Stability metrics such as overshoot, undershoot, rise time, phase margin and gain margin were measured to evaluate and analyze the stability of the converter. These metrics were measured with the original model including the current sharing network that allows load sharing between multiple MISO modules. The simulation results demonstrate that based on the existing model, the system is stable with a gain margin of infinity and phase margin of around 40 degrees at crossover frequency of 47kHz with nominal input voltage of 24V. Another compensator was proposed to overcome the shortcomings of the original compensator model with respect to the overshoot and phase margin. The new compensator model improved the phase margin at the same crossover frequency with a higher rise time and lowered percent overshoot. Additional improvements and tradeoffs are further discussed to help with the decision when designing a compensator for DC-DC converter that uses the current mode control technique.

This project proposes a new hybrid voltage divider DC-DC converter that utilizes switching capacitors and inductors to produce zero voltage switching (ZVS) at the turn on state of its switches. By achieving ZVS, the switching losses are significantly reduced; thus, increasing the overall efficiency of the converter at various loads. The goal for this thesis is to perform analysis of the operation of the converter, derive equations for sizing the main components, and demonstrate its functionality through computer simulation and hardware prototype. Results of the simulation and hardware testing show that the proposed converter produces the desired output voltage while providing the zero voltage switching benefits. The converter’s efficiency reaches above 92% starting from 1A load and continues to increase to 97.6% at 4A load. Overall, results from this thesis verifies the potential of the proposed converter as an alternative solution to achieve a very efficient DC-DC solution when half of the input voltage is required at the output without the use of complex feedback control circuitry.

This thesis presents the design, simulation, and hardware implementation of a proposed method for improving efficiency of voltage regulator. Typically, voltage regulator used for noise-sensitive and low-power applications involves the use of a linear regulator due to its high power-supply rejection ratio properties. However, the efficiency of a linear regulator depends heavily on the difference between its input voltage and output voltage. A larger voltage difference across the linear regulator results in higher losses. Therefore, reducing the voltage difference is the key in increasing regulator’s efficiency. In this thesis, a pre switching regulator stage with positive voltage tracking cascaded to a linear regulator is proposed to provide an input voltage to a linear regulator that is slightly above the output of the linear regulator. The tracking capability is needed to provide the flexibility in having different positive output voltage levels while maintaining high overall regulator’s efficiency. Results from simulation and hardware implementation of the proposed system showed efficiency improvement of up to 23% in cases where an adjustable output voltage is necessary. Load regulation performance of the proposed method was also overall better compared to the case without the output voltage tracking method.

High voltage power supply design presents unique requirements, combining safety, controllability, high performance, and high efficiencies. A new Resonant Self-Tracking Current-Fed Converter (RST-CFC) is investigated as a proof-of-concept of a high voltage power supply particularly for an X-ray system. These systems require fast voltage rise times and low ripple to yield a clear image. The proposed converter implements high-frequency resonance among discrete components and transformer parasitics to achieve high voltage gain, and the self-tracking nature ensures operation at maximum gain while power switches achieve zero-voltage switching across the full load range. This converter exhibits an inherent indefinite short-circuit capability. Theoretical results were obtained through simulations and verified by experimental results through a complete test configuration. Converter topology viability was confirmed through hardware testing and characterization.