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.

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

Analytical and experimental considerations of the noise suppression characteristics of a typical dc-to-dc converter with a two-winding reactor are described. The high-frequency equivalent circuits for external noise are presented which are composed of parasitic parameters and have parallel and series resonances. The high-frequency responses calculated from these equivalent circuits agree well with the experimental results. Effects of the parasitic parameters on the noise suppression capability are discussed.

Noise Suppression Characteristics of a dc-to-dc Converter

A simple and reliable contact-less battery charger for electric vehicles is proposed. It's feature is one body of a power factor correction(PFC) converter and a high frequency inverter(HFI) where the low side switch of an HFI works also as the boost switch of an PFC in discontinuous conduction mode which results in high input power factor and low harmonic distortion without any feed-forward control. The exiting current of the inductive connector, complied with SAEJ1773, effectively works to make the converter operating in ZVS condition. Another feature is that the charger is controlled by only one magnetically coupled variable frequency oscillator which was developed by the authors. This paper analyzes the circuits, gives a design example, shows the inductive connector and the oscillator, and experimental results. An 1.7kW output prototype charger achieved charging efficiency of 87.4% among total one cycle charging, over all efficiency of 90% at heavy load and over 98% of input power factor.

One Converter Type Contact-less Charger for Electric Vehicles

A one-converter contactless charger for electric vehicles

A snubber circuit protects semiconductor switches in a dc-dc converter from voltage stresses. The snubber composed of a resistor and a capacitor, namely the RC snubber, is used widely for protection circuit, although the power dissipation in RC snubbers deteriorates the power efficiency of converters. To remedy this drawback, a nondissipative LC snubber composed of an inductor, a capacitor and diodes has been developed.

The LC snubber is not only nondissipative in principle but also has a feature to reduce the switching power-loss in semiconductor switches. As for the design of the snubbers, for the RC snubbers the power dissipation in the snubber circuit is the point to be considered; and for the LC snubber, the power loss in the semiconductor switch is taken as a criterion from its features.

In this paper, the design procedure of the LC snubber in a forward converter is discussed in the following order: First, the operation of a forward converter with the LC snubber is examined. Next, the energy loss in a switching transistor is evaluated, and the condition to minimize this energy loss is provided. As a result, the procedure to determine the optimum values of the snubber capacitor and snubber inductor is reported.

Design of a nondissipative lc snubber in a forward converter

Analytical and experimental considerations in the constant voltage transformer are presented. The constant voltage transformer consists of a linear reactor, a linear transformer, a capacitor, a triac, and a feedback circuit. The feedback circuit is used to make the triac fire precisely at any angle from zero to ?/2 so as to keep output voltage constant. An analysis of this circuit is presented in which the higher harmonic currents generated in the triac are neglected and the output voltage is assumed to be kept constant. The experimental results agree well with the theoretical value with respect to the load characteristic, the voltage characteristic, the power factor, and the jumping phenomenon.

Koosuke Harada

Papers

Noise Suppression Characteristics of a dc-to-dc Converter

One Converter Type Contact-less Charger for Electric Vehicles

A one-converter contactless charger for electric vehicles

Design of a nondissipative lc snubber in a forward converter

Analysis of a Resonant Converter Controlled by Triac