Described herein are improved configurations for a wireless power converter that includes at least one receiving magnetic resonator configured to capture electrical energy received wirelessly through a first oscillating magnetic field characterized by a first plurality of parameters, and at least one transferring magnetic resonator configured to generate a second oscillating magnetic field characterized by a second plurality of parameters different from the first plurality of parameters, wherein the electrical energy from the at least one receiving magnetic resonator is used to energize the at least one transferring magnetic resonator to generate the second oscillating magnetic field.

Wireless energy transfer converters

A variable type magnetic resonator includes an array of resonators each having one of at least two substantially different magnetic dipole moment orientations and at least one power and control circuit configured to selectively connect to and energize at least one of the array of resonators.

Wireless energy transfer using variable size resonators and system monitoring

Solid-state switch mode AC-DC converters having high-frequency transformer isolation are developed in buck, boost, and buck-boost configurations with improved power quality in terms of reduced total harmonic distortion (THD) of input current, power-factor correction (PFC) at AC mains and precisely regulated and isolated DC output voltage feeding to loads from few Watts to several kW. This paper presents a comprehensive study on state of art of power factor corrected single-phase AC-DC converters configurations, control strategies, selection of components and design considerations, performance evaluation, power quality considerations, selection criteria and potential applications, latest trends, and future developments. Simulation results as well as comparative performance are presented and discussed for most of the proposed topologies.

Comprehensive Study of Single-Phase AC-DC Power Factor Corrected Converters With High-Frequency Isolation

Techniques are described herein that are capable of increasing efficiency of wireless power transfer. A wireless power transfer system includes features that allow the system to be deployed in public spaces such as airports or in commercial establishments such as restaurants or hotels to allow a user to recharge one or more portable electronic devices while away from home. To accommodate wireless recharging of a variety of device types and states, the system may receive parameters and/or state information associated with a portable electronic device to be recharged and may control the wireless power transfer in accordance with such parameters and/or state information. For instance, the system may increase efficiency of the wireless power transfer based on such parameters and/or state information. The system may also provide a secure and efficient means for obtaining required payment information from the user prior to the wireless power transfer, thereby facilitating fee-based recharging.

Increasing efficiency of wireless power transfer

This paper presents a power inverter tailored for low-power photovoltaic (PV) systems. The inverter features high reliability, thanks to a circuit topology that obviates aluminum electrolytic capacitors from the circuit. Moreover, all components, including logic and control, have been designed to exhibit high reliability at high temperatures. Three conversion stages form the power topology. First, a full bridge connected to a high-frequency transformer and a full-bridge rectifier amplifies the voltage of the PV panel to approximately 475 V. This stage is controlled by using a phase-shift pulsewidth-modulation controller that permits zero-voltage switching, thereby minimizing losses. Second, a buck converter is connected in series with the rectifier and is controlled by using current mode in order to shape the current injection into a rectified sine wave. Last, a full bridge is operated at line frequency to unfold the current injection. The amplification stage has a proportional compensator that maintains the voltage at the PV terminals constant. The current injection stage has a proportional-derivative compensator that controls the amplitude of the grid current so that the dc-link average voltage is maintained constant. Experimental results show that the peak efficiency of the system is 89%, and the total current harmonic distortion is below 5%. Finally, analyses show a designed lifetime of approximately ten years.

Long-Lifetime Power Inverter for Photovoltaic AC Modules

A new zero-voltage-switching (ZVS) phase-shift full-bridge (PSFB) converter with low conduction losses is proposed. It is based on the PSFB converter with series-connected two transformers, which features wide ZVS ranges. By adding a capacitor, the proposed converter overcomes the disadvantage of the based converter, such as the high circulating energy. Furthermore, the turns ratio of the transformers can be increased as well. Therefore, high efficiency of the proposed converter can be achieved. Operational principles and experimental results for a 100-W (5 V, 20 A) prototype are presented to validate the proposed converter.

New zero-voltage-switching phase-shift full-bridge converter with low conduction losses

In outdoor light-emitting diode (LED) lighting systems, there are a lot of applications. Depending on the output power rating, the power stage to drive an LED can be classified into single-stage and two-stage structures. The single-stage structure is for low-power LED lighting applications. However, it is difficult to apply at over 60-70 W of output power because of its low efficiency and huge transformer at high power. On the other hand, the two-stage structure is usually used for high power applications. However, it is undesirable to cover wide output power range because of its poor power factor (PF) under the light load condition. To solve these problems, this paper proposes a new pulse duty cycle control method with pulse frequency modulation for an interleaved single-stage flyback ac-dc converter. The proposed converter provides high efficiency under heavy loads with low ac line condition and under light loads with high ac line condition. In addition, the proposed converter shows high PF and low total harmonic distortion even when the output power is very low. As a result, a single LED ac-dc converter can cover wide power range for outdoor LED lighting applications. To verify the validity of the proposed converter, an 81-W prototype converter has been implemented and experimented on.

A New Control Method of Interleaved Single-Stage Flyback AC–DC Converter for Outdoor LED Lighting Systems

A new phase shift full bridge (PSFB) converter with series-connected two transformers is proposed. The proposed converter shows wide zero voltage switching (ZVS) ranges and no output inductor is needed since each transformer individually acts as an inductor or a transformer during different times of the switching cycle. The operational principle, large signal modeling, and design equations are presented. Experimental results demonstrate that the proposed converter can achieve a significant improvement in the efficiency for a 100W (5 V, 20 A) telecommunication on-board power supply.

Analysis and design of phase shift full bridge converter with series-connected two transformers

A wireless power transmission system according to an exemplary embodiment of the present invention includes: a source coil at a primary side; a load coil at a secondary side; and at least two intermediate coils coupled with each other in an insulated manner with a predetermined turn ratio with respect to the source coil. An effective inductance of the source coil is increased by the at least two intermediate coils and thus a coupling coefficient between the source coil and the load coil is increased.

Wireless power transfer system

This paper presents a small-signal ac modeling of a feedback system for a flyback light-emitting diode (LED) driver. From this analysis, a dimming-feedback control method, which has a constant loop gain at dc, is proposed for dimmable LED drivers. Since the proposed method controls the steady-state error of the feedback system, an additional phase angle detection circuit and a LED current adjusting circuit are not required to control the output LED current according to the phase angle of the input voltage in a TRIAC-dimmable LED driver. Therefore, the proposed control method provides a simple structure, small size, and low bill of materials. A prototype of a flyback LED driver with the proposed dimming-feedback control method is implemented and experimented on to verify the validity of the analysis and the proposed control method. The prototype shows that the proposed control method varies the output LED current according to the phase angle of the TRIAC dimmer with no additional circuits. Thus, the proposed control method has high compatibility with TRIAC dimmers and can be applied to any dimmable LED driver with a nondimmable control integrated circuit.

Gwan-Bon Koo

Papers

New zero-voltage-switching phase-shift full-bridge converter with low conduction losses

A New Control Method of Interleaved Single-Stage Flyback AC–DC Converter for Outdoor LED Lighting Systems

Analysis and design of phase shift full bridge converter with series-connected two transformers

Wireless power transfer system

Dimming-Feedback Control Method for TRIAC Dimmable LED Drivers