MPPT Solar Charge Contoller For Portable

The purpose of our senior project was to design and prototype an MPPT charge controller for small capacity PV panels under varying temperature and irradiance conditions to charge portable devices. In this paper we discuss our research, simulation, design, and testing to develop an MPPT solar charge controller. Furthermore, we presented our results and findings from testing our design. An MPPT solar charge controller is feasible and affordable if implemented on a PCB board. Due to MPPT’s affordability and increased efficiency under dynamic conditions, an MPPT solar charge controller for portable devices would be more effective than solar chargers currently sold without MPPT

Isolated Single-stage Power Electronic Building Blocks Using Medium Voltage Series-stacked Wide-bandgap Switches

The demand for efficient power conversion systems that can process the energy at high power and voltage levels is increasing every day. These systems are to be used in microgrid applications. Wide-bandgap semiconductor devices (i.e. Silicon Carbide (SiC) and Gallium Nitride (GaN) devices) are very promising candidates due to their lower conduction and switching losses compared to the state-of-the-art Silicon (Si) devices. The main challenge for these devices is that their breakdown voltages are relatively lower compared to their Si counterpart. In addition, the high frequency operation of the wide-bandgap devices are impeded in many cases by the magnetic core losses of the magnetic coupling components (i.e. coupled inductors and/or high frequency transformers) utilized in the power converter circuit. Six new dc-dc converter topologies are propose. The converters have reduced voltage stresses on the switches. Three of them are unidirectional step-up converters with universal input voltage which make them excellent candidates for photovoltaic and fuel cell applications. The other three converters are bidirectional dc-dc converters with wide voltage conversion ratios. These converters are very good candidates for the applications that require bidirectional power flow capability. In addition, the wide voltage conversion ratios of these converters can be utilized for applications such as energy storage systems with wide voltage swings

Maximum Peak Power Tracker

The design and implementation of a Maximum Peak Power Tracking system for a photovoltaic array using boost DC-DC converter topology is proposed. Using a closed-loop microprocessor control system, voltage and current are continuously monitored to determine the instantaneous power. Based on the power level calculated, an output pulse width modulation signal is used to continuously adjust the duty cycle of the converter to extract maximum power. Using a Thevenin power source as well as a solar panel simulator, system design testing confirms simulation of expected results and theoretical operation is obtained

HIGH EFFICIENCY BASE DRIVE DESIGNS FOR POWER CONVERTERS USING SILICON CARBIDE BIPOLAR JUNCTION TRANSISTORS

This thesis explores the base driver designs for Silicon Carbide Bipolar Junction Transistors (SiC BJTs) and their applications for power converters. SiC is a wide bandgap semiconductor which has been the focus of recent researches as it has overcome the several of physical restrictions set by the silicon material. Compared with silicon bipolar devices, SiC BJTs have several advantages including a higher maximum junction temperature, higher current gain and lower switching power losses. Transient power losses are low and temperature-independent in a wide range of junction temperatures. With junction temperature capable of being between 25ºC to 240ºC, SiC BJTs have been of great interest in industry. As a current-driven device, the base driver power consumption is always a major concern. Therefore, high efficiency base drive designs for SiC BJT need to be investigated before this power device can be widely used in industry

Design Approaches to Enhance Power Density in Power Converters for Traction Applications

This dissertation presents a design strategy to increase the power density for automotive Power Conversion Units (PCUs) consisting of DC-DC and DC-AC stages. The strategy significantly improves the volumetric power density, as evident by a proposed PCU constructed and tested having 55.6 kW/L, representing an 11.2 % improvement on the Department of Energy’s 2025 goal of 50 kW/L for the same power electronics architecture. The dissertation begins with a custom magnetic design procedure, based on optimization of a predetermined C-core geometrical relationship and custom Litz wire. It accounts for electrical and thermal tradeoffs to produce a magnetic structure to best accomplish volume and thermal constraints. This work is coupled with a control strategy for the DC-DC converter whereby a variable-frequency Discontinuous Conduction Mode (DCM) control is used to further reduce the required values of the passive components, to provide an increase in power density and a large improvement of low-power-level efficiency, experimentally demonstrated at full power through an 80 kW Interleaved Boost Converter. Integration of this enhanced DC-DC stage to the DC-AC stage requires a DC-Link capacitor, which hinders achieving power density targets. Increasing the switching frequency is an established method of reducing the size of passives. However, it is the RMS current sizing requirements that diminishes any gains achieved by raising the switching frequency. A synchronous carrier phase shift-based control algorithm, that aligns the output current of the boost stage with the input current of an inverter, is proposed to reduce the RMS current in the DC-Link capacitor by up to 25% and an average 20% smaller capacitor volume. Lastly, a new electrothermal platform based on paralleled discrete devices is presented for a 50 kW traction inverter. Embedded capacitors within the vacant volume of the hybrid material thermal management structure enables higher power density (155 kW/L) and significantly reduces cost

Design Approaches to Enhance Power Density in Power Converters for Traction Applications

This dissertation presents a design strategy to increase the power density for automotive Power Conversion Units (PCUs) consisting of DC-DC and DC-AC stages. The strategy significantly improves the volumetric power density, as evident by a proposed PCU constructed and tested having 55.6 kW/L, representing an 11.2 % improvement on the Department of Energy’s 2025 goal of 50 kW/L for the same power electronics architecture. The dissertation begins with a custom magnetic design procedure, based on optimization of a predetermined C-core geometrical relationship and custom Litz wire. It accounts for electrical and thermal tradeoffs to produce a magnetic structure to best accomplish volume and thermal constraints. This work is coupled with a control strategy for the DC-DC converter whereby a variable-frequency Discontinuous Conduction Mode (DCM) control is used to further reduce the required values of the passive components, to provide an increase in power density and a large improvement of low-power-level efficiency, experimentally demonstrated at full power through an 80 kW Interleaved Boost Converter. Integration of this enhanced DC-DC stage to the DC-AC stage requires a DC-Link capacitor, which hinders achieving power density targets. Increasing the switching frequency is an established method of reducing the size of passives. However, it is the RMS current sizing requirements that diminishes any gains achieved by raising the switching frequency. A synchronous carrier phase shift-based control algorithm, that aligns the output current of the boost stage with the input current of an inverter, is proposed to reduce the RMS current in the DC-Link capacitor by up to 25% and an average 20% smaller capacitor volume. Lastly, a new electrothermal platform based on paralleled discrete devices is presented for a 50 kW traction inverter. Embedded capacitors within the vacant volume of the hybrid material thermal management structure enables higher power density (155 kW/L) and significantly reduces cost

Design of a bidirectional energy buffer using a switched-capacitor converter and supercapacitors for an auxiliary EIS converter for fuel cell stacks

Fuel cell as an attractive clean energy source has gained a great deal of interest. To increase the durability and reliability of fuel cells, diagnostics systems that can detect degradation and faults inside fuel cell stacks in end applications are highly in need. Electrochemical impedance spectroscopy (EIS), among other methods, is a promising characterizing tool for diagnostics and condition monitoring of fuel cells. It was traditionally only applied to single-cell or short stacks at low-power levels and required special laboratory equipment, but was recently brought to high-power stacks too which was made possible by many technological advancements. This is mainly owing to a growing interest in performing in situ EIS as a non-destructive method without the need for dismantling the stack. Unlike traditional approaches which relied on extra equipment, converter-based EIS provides attractive solutions for this purpose. In this thesis, the design and utilization of a bidirectional energy buffer module composed of a switched-capacitor converter (SCC) and a supercapacitor string for a new auxiliary EIS converter solution is presented. The module is designed towards having a more compact auxiliary converter unit. The design of the proposed energy buffer module is investigated in detail and a guideline is provided considering the application-specific optimal conversion ratio, supercapacitor string capacitance, and the probable limitations imposed by high EIS frequencies on certain situations. In a nutshell, the proposed switched-capacitor converter module (SCCM) consists of a bidirectional high voltage-gain SCC connected with supercapacitor string helps with the compactness and miniaturization of the entire auxiliary EIS converter and eliminating the potential problems of electrolytic capacitors such as bulkiness and limited lifetime due to the impact of ripples. The SCCM energy buffer with a high voltage gain offers a high buffering ratio for utilizing supercapacitors as the energy storage device

Evaluation of Losses in HID Electronic Ballast Using Silicon Carbide MOSFETs

HID lamps are used in applications where high luminous intensity is desired. They are used in a wide range of applications from gymnasiums to movie theatres, from parking lots to indoor aquaria, from vehicle headlights to indoor gardening. They require ballasts during start-up and also during operation to regulate the voltage and current levels. Electronic ballasts have advantages of less weight, smooth operation, and less noisy over electromagnetic ballasts. A number of topologies are available for the electronic ballast where control of power electronic devices is exploited to achieve the performance of a ballast for lighting. A typical electronic ballast consists of a rectifier, power factor control unit, and the resonant converter unit. Power factor correction (PFC) was achieved using a boost converter topology and average current mode control for gate control of the boost MOSFET operating at a frequency of 70 kHz. The PFC was tested with Si and SiC MOSFET at 250 W resistive load for varying input from 90 V to 264 V. An efficiency as high as 97.4% was achieved by Si MOSFET based PFC unit. However, for SiC MOSFET, the efficiency decreased and was lower than expected. A maximum efficiency of 97.2% was achieved with the SiC based PFC. A simulation model was developed for both Si and SiC MOSFET based ballasts. The efficiency plots are presented. A faster gate drive for SiC MOSFET could improve the efficiency of the SiC based systems