There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Most of the signal processing that we will study in this course involves local operations on a signal, namely transforming the signal by applying linear combinations of values in the neighborhood of each sample point. You are familiar with such operations from Calculus, namely, taking derivatives and you are also familiar with this from optics namely blurring a signal. We will be looking at sampled signals only. Let's start with a few basic examples. Local difference Suppose we have a 1D image and we take the local difference of intensities, DI(x) = 1 2 (I(x + 1) − I(x − 1)) which give a discrete approximation to a partial derivative. (We compute this for each x in the image.) What is the effect of such a transformation? One key idea is that such a derivative would be useful for marking positions where the intensity changes. Such a change is called an edge. It is important to detect edges in images because they often mark locations at which object properties change. These can include changes in illumination along a surface due to a shadow boundary, or a material (pigment) change, or a change in depth as when one object ends and another begins. The computational problem of finding intensity edges in images is called edge detection. We could look for positions at which DI(x) has a large negative or positive value. Large positive values indicate an edge that goes from low to high intensity, and large negative values indicate an edge that goes from high to low intensity. Example Suppose the image consists of a single (slightly sloped) edge:

http://ieeexplore.ieee.org/iel5/5/31307/01456462.pdf

Linear systems

Leu-M

This paper overviews theoretical and practical design issues related to inductive power transfer systems and verifies the developed theory using a practical electric vehicle battery charger. The design focuses on the necessary approaches to ensure power transfer over the complete operating range of the system. As such, a new approach to the design of the primary resonant circuit is proposed, whereby deviations from design expectations due to phase or frequency shift are minimized. Of particular interest are systems that are neither loosely nor tightly coupled. The developed solution depends on the selected primary and secondary resonant topologies, the magnetic coupling coefficient, and the secondary quality factor.

Design considerations for a contactless electric vehicle battery charger

A system and method for variable power transfer in an inductive charging or power system. In accordance with an embodiment the system comprises a pad or similar base unit that contains a primary, which creates an alternating magnetic field. A receiver comprises a means for receiving the energy from the alternating magnetic field from the pad and transferring it to a mobile device, battery, or other device. In accordance with various embodiments, additional features can be incorporated into the system to provide greater power transfer efficiency, and to allow the system to be easily modified for applications that have different power requirements. These include variations in the material used to manufacture the primary and/or the receiver coils; modified circuit designs to be used on the primary and/or receiver side; and additional circuits and components that perform specialized tasks, such as mobile device or battery identification, and automatic voltage or power-setting for different devices or batteries.

System and method for inductive charging of portable devices

A steady-state analysis is presented with complete characterization of the converter operation. A small-signal model of the converter is established. The design procedures based on the analysis are presented and the various losses in the circuit assessed. Critical design considerations for a high-power, high-voltage application are analyzed. The results of the analysis are verified using a high-voltage. 2 kW prototype. >

Design considerations for high-voltage high-power full-bridge zero-voltage-switched PWM converter

State-of-charge and capacity estimation of lithium-ion battery using a new open-circuit voltage versus state-of-charge

By applying the loop gain analysis technique, a forbidden region for the polar plot of the ratio of impedances at the interface between two cascaded power subsystems is determined. A method of transforming the forbidden region into a load impedance specification for a given source impedance is developed. The method assures system stability and minimal performance degradation of the distributed power system, while allowing impedance overlap at the interface. >

A method of defining the load impedance specification for a stable distributed power system

In this paper, the design of a contactless charger for the lithium-ion battery of a cellular phone is presented. In this charger, the primary core of the transformer is in the charger unit and the secondary core is in the telephone. The gap (3 mm) between them is the thickness of the two plastic cases. The transformer core design for the maximum coupling coefficient with the size constraint on the secondary side is presented. Analysis of the primary-side series resonant power converter with the loosely coupled transformer is performed, and the design optimization is presented. For the battery-charging control, a simple control circuit is presented and its performance is verified from the experimental results.

Design of a contactless battery charger for cellular phone

A power supply system using a transcutaneous transformer to power an artificial heart through intact skin has been designed and built. In order to realize both high-voltage gain and minimum circulating current, compensation of leakage inductances on both sides of a transcutaneous transformer is proposed. A frequency region which realizes the robustness against coupling coefficient and load variation is identified. In this region, the power converter has inherent advantages such as zero-voltage switching (ZVS) or zero-current switching (ZCS) of the switches, high-voltage gain, minimum circulating current and high efficiency.

Bo-Hyung Cho

Papers

Design considerations for high-voltage high-power full-bridge zero-voltage-switched PWM converter

State-of-charge and capacity estimation of lithium-ion battery using a new open-circuit voltage versus state-of-charge

A method of defining the load impedance specification for a stable distributed power system

Design of a contactless battery charger for cellular phone

An energy transmission system for an artificial heart using leakage inductance compensation of transcutaneous transformer