Charging Area Extensible Wireless Power Transfer System with an Orthogonal Structure

This paper presents a wireless power transfer (WPT) system with an extensible charging area. The proposed system uses a vertical receiver with an 8-shape transmitter. Conventionally, circular coil structures suffer from coupling condition variation when used for dynamic wireless charging applications. In this paper, an 8-shape feeding loop is proposed to construct a directional magnetic field for an orthogonal receiver to receive power efficiently. Furthermore, the transmitter can be extended easily by cascading the transmitter modules. Experimental results have demonstrated a power transfer efficiency of 59% - 70 % when a receiver is moving along a 3-module transmitter array. The proposed structure can be a very good candidate for dynamic WPT applications, especially the charging of moving electric vehicles

Co-Plane Co-Axial Inductive Coils for Wireless Power Transfer

Many attempts have been exposed in designing energy-efficient and reliable wireless power transfer module at low frequency. This wireless power transfer technology is expected to modify the scenario of electrical power distribution for the consumer. A new concept of wireless power transfer coils is proposed to increase the output power capacity. This can be made possible by using coaxial inductive coils, just like a transformer. There will be less air gap in between the transmitter and the receiver coils. Hence, electromagnetic field loss by radiation and fringing effect can be reduced. The angular displacement between the inductive coils is kept to the minimum. In case of the distance between coils, the proposed design will reduce the distance up to 2 times. This design helps reduce magnetic flux waste and improve the electromagnetic energy transfer. Overall system performance and efficiency will be improved, compared to the inductive coils used in conventional wireless power transfer systems. Full 3-D simulations are performed to observe the performance in energy transfer of the proposed co-plane co-axial inductive coils, in terms of its the geometrical configuration

Dynamic Wireless Power Transfer for Warehouse Robots

The possible wireless power transfer (WPT) consists of stationary and dynamic wireless power transfer (DWPT) for warehouse robots power charging. The stationary wireless charging for warehouse robots has several disadvantages of long charging time, non-running, frequent charging, etc., whereas DWPT is a broad application prospect and is considered one of the best solutions above-stated problems. This paper proposes a maximum transfer efficiency and distance method in the DWPT for Warehouse Robots using a magnetic resonant (MR) inductive coupling subsection coil powered by a transmitter coil (Tx). The optimal efficiency is reached when three adjacent subsection coil (SC) are simultaneously powered on a single Tx. The two critical parameters in DWPT are Power Delivered to the Load (PDL) and Power Transfer Efficiency (PTE). The design results of an MR inductive coupling and a magnetic resonant inductive coupling subsection coil (MRSC) WPT optimized for a 20 kHz operating frequency at 8-cm, 11-cm, and 16-cm coupling distance show PTE (an MR inductive/MRSC) WPT of 85/87%, 65/70%, 45/65%, respectively, and the PDL of the MRSC WPT 3.2%, 11.1%, and 50% respectively higher than an MR inductive WPT. Results also show that the robot moves smoothly along the transmission track, and having the MRSC underneath is a less complicated system

Maximum Energy Efficiency Operation of Series-Series Resonant Wireless Power Transfer Systems Using On-Off Keying Modulation

Maximum energy efficiency in wireless power transfer (WPT) systems can be achieved through the use of magnetic resonance technique at a certain load resistance value. However, practical load resistance is not constant. Previously, a switched mode dc-dc converter was used in the receiver circuit to emulate an equivalent load resistance for maximum energy efficiency. In this paper, a new approach based on the On-Off Keying is proposed to achieve the high energy efficiency operation over a wide range of load power without using an impedance-matching dc-dc power converter. This simple and effective method has reduced average switching frequency and switching losses. It can be applied to any series-series resonant WPT system designed to operate at a constant output voltage. Practical measurements have confirmed the validity of the proposal

A Defected Metasurface for Field-Localizing Wireless Power Transfer

The potential of wireless power transfer (WPT) has attracted considerable interest for various research and commercial applications for home and industry. Two important topics including transfer efficiency and electromotive force (EMF) leakage are concerned with modern WPT systems. This work presents the defected metasurface for localized WPT to prevent the transfer efficiency degraded by tuning the resonance of only one-unit cell at the certain metasurface (MTS). Localization cavities on the metasurface can be formed in a defected metasurface, thus fields can be confined to the region around a small receiver, which enhances the transfer efficiency and reduces leakage of electromagnetic fields. To create a cavity in MTS, a defected unit cell at the receiving coils’ positions for enhancing the efficiency will be designed, aiming to confine the magnetic field. Results show that the peak efficiency of 1.9% for the case of the free space is improved to 60% when the proposed defected metasurface is applied, which corresponds to 31.2 times enhancements. Therefore, the defected MTS can control the wave propagation in two-dimensional of WPT system

Sensorless control of the charging process of a dynamic inductive power transfer system with interleaved nine-phase boost converter

The paper proposes a technique for the control of the charging process in a dynamic inductive power transfer system for automotive applications. This technique is based on an impedance control loop on the receiver side. The proposed control allows to carry out the different phases of the charging process in absence of a communication link between ground and vehicle side. The charging process starts with a sensorless procedure for the identification of the actual presence of the vehicle over the receiver. The same control technique introduces several advantages in terms of interoperability between systems having different requirements in terms of power demand. A 11 kW prototype has been implemented based on a transmitter 1.5 meters long as compromise solution between the long track coil and the lumped one. The power management of the receiver side is provided by a nine-phase interleaved boost converter. The experimental results prove the effectiveness of the proposed control together with a good matching with the developed theoretical equations set for the system description