SmartGrid

TOPIC: Power Electronics: Dc-dc and DC-AC converters

In this lecture, we will briefly describe the various topologies that are used in the design of dc-dc converters commonly used in battery-operated systems. We will also describe the basic modulations used in Dc-ac converters that are commonly used in electric motor drives.

In this lecture, we will introduce how power electronics components operate to deliver power from the grid to a dc source efficiently. We will also describe how to measure the distortion introduced by the converters as well as the allowable limits in distortion.

This lecture will discuss some of the foundations of health-conscious lithium-ion battery control. The lecture will motivate the need for health-conscious control, and discuss some of the models used for representing battery performance and degradation dynamics in the literature. Based on these foundations, examples of health-conscious control problem formulations, solution methods, and results will be presented for cell-, pack-, system-, and infrastructure-level applications. Connections between health-conscious control and more classical battery control challenges such as pack balancing will be discussed, motivating a broader perspective on those more traditional challenges.

Battery-management systems (BMS) comprise electronics and software designed to monitor the status of a battery pack, estimate its present operating state, and advise the battery load regarding the maximum amount of power that may be sourced or sunk by the load at every point in time while maintaining safety and acceptable battery-pack service life. This lecture will first discuss BMS sensing requirements imposed by these tasks. It will then give an introduction to state-of-art equivalent-circuit-model-based algorithms to estimate the battery pack's operating state: nonlinear Kalman filters for state-of-charge, recursive total-least-squares methods for state-of-health, direct computations for state-of-energy, and a bisection method for state-of-power.

Lithium-ion battery packs for transportation and grid services represent a large investment that must be continuously monitored to ensure safety, to maximize performance, and to extend life to the greatest degree possible. The best available battery-management methods are model based; that is, they depend on sets of equations ("models") that describe the behaviors of the lithium-ion cells in the battery pack in order to perform their management tasks. This lecture will first derive "equivalent-circuit" models, which are presently state-of-art. It will next introduce "physics-based" models, which have potential benefits for future battery-management systems. Physics-based models are computationally complex, so a method will be presented to develop highly accurate reduced-order models suitable for battery management. Finally, a high-level overview of mechanisms of cell degradation will be given to motivate power-limits computations to be discussed in the next lecture.

We will discuss the characteristics that define a battery, such as energy density, safety, and efficiency. Materials properties determine the operating envelope of the batteries, such as temperature. Popular positive electrode chemistry for lithium-ion batteries will be reviewed.

We will introduce the four main components of a battery: positive electrode, negative electrode, electrolyte, and current collector. A battery is classified by the phase of the electrode, electrolyte, energy carrier and type of chemical reaction. We will briefly introduce lithium-ion, solid-state, liquid metal, sodium sulfur and lithium air battery chemistries. Finally, we will discuss charging and discharging characteristics.

Buildings account for the largest share of U.S. greenhouse gas emissions at 32% of the total, followed by industry at 30%, transportation at 29%, and agriculture at 9%. Clearly, any program to greatly reduce greenhouse gas emissions must include buildings. This talk will explore the opportunities and challenges to greatly reducing greenhouse gas emissions in the building sector, using as a case study a recent solar retrofit of an existing house that rendered it "zero-carbon." Implications for the future of the utility system will be discussed.

Thin-film solar cells, which use light-weight, highly-absorbing semiconductors, have the potential to dramatically lower manufacturing costs and accelerate deployment of solar energy via mechanically flexible architectures. Hybrid metal halide perovskites are the leading materials for this next-generation solar technology by virtue of their unprecedented optoelectronic properties and their synthesis from earth-abundant elements. The groundbreaking promise of perovskites is that they can be manufactured by scalable solution-coating methods, making them a potentially low-cost and high-performance energy technology with projected levelized cost of electricity (LCOE) below 3¢ / kWh.

This talk will discuss the current understanding of the optoelectronic properties of perovskites as well as how these properties inform the design of single-junction and tandem perovskite-silicon cell architectures. We will consider routes to upscaling perovskite module fabrication and look at challenges related to the fundamental thermomechanical reliability of these material systems.

Competing standards often proliferate in early stages of product markets and may lead to socially inefficient investment. This paper studies the effect of unifying three incompatible standards for charging electric vehicles in the U.S. from 2011 to 2015. I develop and estimate a structural model of vehicle demand and charging network investment to quantify the impact of a uniform charging standard. Variation in federal and state subsidies identify the demand elasticities. Counterfactual simulations show moving to a uniform charging standard increases consumer surplus by $500 million; car manufacturers build 2.8% fewer charging locations and sell 20.8% more electric vehicles.