The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed. The techniques are taken from the literature dating back to the earliest methods. It is shown that at least 19 distinct methods have been introduced in the literature, with many variations on implementation. This paper should serve as a convenient reference for future work in PV power generation.

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Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques

Wireless power transfer (WPT) using magnetic resonance is the technology which could set human free from the annoying wires. In fact, the WPT adopts the same basic theory which has already been developed for at least 30 years with the term inductive power transfer. WPT technology is developing rapidly in recent years. At kilowatts power level, the transfer distance increases from several millimeters to several hundred millimeters with a grid to load efficiency above 90%. The advances make the WPT very attractive to the electric vehicle (EV) charging applications in both stationary and dynamic charging scenarios. This paper reviewed the technologies in the WPT area applicable to EV wireless charging. By introducing WPT in EVs, the obstacles of charging time, range, and cost can be easily mitigated. Battery technology is no longer relevant in the mass market penetration of EVs. It is hoped that researchers could be encouraged by the state-of-the-art achievements, and push forward the further development of WPT as well as the expansion of EV.

Wireless Power Transfer for Electric Vehicle Applications

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

Maximum power point tracking (MPPT) is used in photovoltaic (PV) systems to maximize the photovoltaic array output power, irrespective of the temperature and irradiation conditions and of the load electrical characteristics. A new MPPT system has been developed, consisting of a buck-type DC/DC converter, which is controlled by a microcontroller-based unit. The main difference between the method used in the proposed MPPT system and other techniques used in the past is that the PV array output power is used to directly control the DC/DC converter, thus reducing the complexity of the system. The resulting system has high-efficiency, lower-cost and can be easily modified to handle more energy sources (e.g., wind-generators). The experimental results show that the use of the proposed MPPT control increases the PV output power by as much as 15% compared to the case where the DC/DC converter duty cycle is set such that the PV array produces the maximum power at 1 kW/m/sup 2/ and 25/spl deg/C.

/pdf/development-of-a-microcontroller-based-photovoltaic-maximum-1r79o424xa.pdf

Development of a microcontroller-based, photovoltaic maximum power point tracking control system

This paper presents analysis of a high-power factor ac-dc converter with a boost converter operating in the discontinuous conduction mode (DCM) and the critical conduction mode (CRM). The converter can be expressed by a nonlinear differential equation for each mode. The equation in DCM is solved analytically by separating its variable (output voltage) into two terms of a ripple component and a direct component, and by linearizing the equation for the ripple component. On the other hand, the equation in CRM can be solved analytically. Furthermore, the source current waveform of the converter is expanded into the Fourier series. As a result, the output voltage, its ripple and the power factor of the converter in DCM and CRM are derived as a function of the circuit parameters, respectively, and verified experimentally. These equations exhibit clearly the effect of each circuit parameter of the converter and the difference between the converter in DCM and in CRM. The converter operating in CRM produces sinusoidal ac current with unity power factor.

Analysis of High Power Factor AC-DC Boost Converter

It is considered that the key to miniaturization of switching power supplies is in high frequency. With respect to the high frequency of switching power supplies, the losses and surge during switching are frequent problems. In switched snubber circuits constructed from parallel connection of a switching element and condenser, it is reported that there is essentially no loss and the surge suppression effects are excellent.



In this paper, with respect to converters incorporating switched snubber circuits, general state equations taking into account low-frequency characteristics are determined by the state averaging method. As a consequence, while taking into account parasitic inductances such as the leakage inductance of transformers and floating inductance of wiring, a unified analysis was made of buck type, boost type, and buck-boost type. Moreover, the general state equations taking into account the parasitic elements of the smoothing condenser were determined by transformation into simple equivalent circuits. The suitability of the analysis was verified by using a flyback converter. The fact that the parasitic inductance in the circuit increases the output impedance is verified quantitatively.

Analysis of switching converters with switched snubber

A Charger with A Magneto-Inductive Connector

A voltage-mode resonant push-pull converter with magnetic power controllers is investigated for the continuous-conduction-mode concerning the output-inductor current. The output voltage is regulated by the PWM process using magnetic amplifiers with the constant switching frequency. This resonant converter has the prominent features of low noise and high efficiency at high-frequency switching. The static characteristics of this converter are analyzed and experimentally confirmed. The stability and the power efficiency are also examined.

Voltage-mode resonant push-pull converter with magnetic power controllers

Operations of parallel-connected Triport UPS systems are discussed. The parallel operation becomes important (1) for increasing the rated kVA of the system and (2) for realizing a redundant system to improve the system reliability. In this paper, we consider the typical parallel operation of two Triports under the normal mode and analyze the current balance conditions which make the ratio of output currents equal to that of the kVA ratings. Experimental results are shown about the current sharing characteristics at steady state, the output voltage transient characteristics for load current variation and so forth.

http://ieeexplore.ieee.org/iel5/4794181/4794182/04794212.pdf

Koosuke Harada

Papers

Analysis of High Power Factor AC-DC Boost Converter

Analysis of switching converters with switched snubber

A Charger with A Magneto-Inductive Connector

Voltage-mode resonant push-pull converter with magnetic power controllers

On the Parallel Operations of Triport UPS Systems