GREEN POWER: |
Solar Energy Generation: This lecture will cover the fundamentals, state of the art and economic trade-offs of modern solar cells and panels. The solar cell technologies that will be explored in detail include Wafer based Thick Silicon cells, Thin Film Silicon cells, other thin film solar cells, such as CIGS and Dye Sensitized Solar Cells, as well as Multi Junction cells and future development directions. Following the discussion of the technological aspects and electrical characteristics of the different solar cells, the economic trade-offs of the whole solar panel system will be covered. Needs and directions for future development will be highlighted to make solar energy generation competitive with traditional fossil fuel-based methods in the future. |
Low-Power Inverters for Solar and other Renewable Energy Applications Line-frequency inverter fundamentals: Basic waveforms (square wave, quasi-square-wave, sine wave), modulation techniques (harmonic cancellation, two-level PWM, three-level and multilevel PWM, space-vector modulation), topologies (single-phase: half-bridge, full-bridge, isolated low-frequency, isolated high-frequency; three-phase), regulation (bus-voltage control, PWM control). Inverter applications: Stand-alone, UPS, motor, grid-connected. Considerations for grid-connected inverters: Interface with the primary energy source, maximum power point tracking, anti-islanding control. |
Power Factor Correction Systems/Circuits Causes and effects of line-current harmonics. Overview of the harmonic limits. Single-phase passive and low-frequency active power-factor correction (PFC). Single-phase non-isolated high-frequency PFC: Converter topologies, control techniques, modeling and feedback-loop design, practical considerations (line-voltage feedforward, line-current distortion vs. transient response, load-current feedforward, inrush-current limit, hold-up time extension with downstream boost converter, reducing rms current in the storage capacitor, auxiliary power supplies). Single-stage isolated power supplies: Single converter with energy storage capacitor at the output side (topologies, storage capacitor considerations, high-efficiency postregulation), combined converters with energy storage at the input side (combining control sections, combining power sections). Three-phase PFC: Passive solutions, active solutions (low-frequency boost PFC rectifier, high-frequency six-switch and three-switch boost PFC rectifiers, high-frequency six-switch and three-switch buck and buck-boost PFC rectifiers). |
Energy Scavenging Systems for Low-Power Applications Issues driving development of Energy Scavenging Systems. Power Requirements for example circuits and systems. Power sources used in energy scavenging systems will be discussed in detail. These can be divided into two major categories: active and passive energy sources from humans and environmental energy sources. Among the environmental energy sources fluid flow, vibrations, RF radiation, solar radiation, charge gradients, temperature fluctuations and pressure variation will be covered, together with the systems used to convert their energy into electric energy. Methods and control techniques will be discussed to optimize the energy extraction from piezoelectric, thermoelectric and variable capacitor based systems. |
Energy Efficient Lighting: Light Sources and Driver Circuits Characteristics of fluorescent lamps and CFLs. Electronic ballast topologies, control methods and circuits. Two stage and single stage implementations. Dimming methods and issues. High intensity LEDs for lighting applications. DC/DC converters and AC/DC converters used in LED driver applications. OLEDS in lighting applications. |
Battery Chargers for Solar Systems Battery chargers in general. MPPT control methods and their implementation for solar cell-based battery charger systems. Circuits techniques for photovoltaic battery chargers. |
Energy Storage for Renewable Energy Applications (latest battery technology/ directions, super capacitors, fuel cells, flywheels, others) The lecture covers energy storage devices usable in photovoltaic systems for low to medium power applications. These include rechargeable batteries, super-capacitors, hydrogen-based storage and flywheels. Latest advances in rechargeable battery technology with emphasis on Lithium-based systems. Different super-capacitor technologies compared to batteries. Hydrogen generation overview and fuel cell technology. Flywheels as energy storage. |
Ultra Low-Power Design and Circuit Techniques A power harvesting supply system typically comprises a power harvester, a conditioning circuit, energy storage and DC/DC converters. This power system supplies micro power sensor, communication, or other circuitry. In these systems typically long periods of idle time with very low power consumption alternates with active high power states. The lecture will cover the design issues of the conditioner circuit, which includes a battery charger. The design goal is to extract every nanojoule of available energy from the power harvester, utilizing appropriate battery charging profiles. Design techniques and circuits of DC/DC converters, applied in these systems, will also be covered, providing high efficiency at a wide range of loads, down to the microampere range. Circuit techniques used in ultra low power analog circuits applicable in power harvesting systems will be presented, including nanoamp biasing, reverse bandgap references with sub-volt supply, active rectifiers, comparators, oscillators, error amplifiers and voltage boosting gate drivers. |