Dariusz Kacprzak

A New Concept: Asymmetrical Pick-Ups for Inductively Coupled Power Transfer Monorail Systems

Inductively coupled power transfer systems have recently proven to be popular in moving vehicle monorail systems situated in difficult environments such as clean rooms. In such applications the magnetic design is critical if low weight high power pick-ups are to be realized. Early designs were largely experimental and used magnetic shapes that easily fit the existing structure. Modern finite-element-modeling packages are now being used to achieve significant alterations to the pick-up shape under the assumption that the monorail structures can be changed. This paper introduces several important magnetic design metrics that must be considered in such a design process, and applies these to various newly proposed and unconventional asymmetrical pick-up shapes. These new pick-ups are shown to be capable of achieving comparable power output with lower ferrite volume/length of the pick-up structure, or significant increases in output power for identical volume/length, to a conventional E-shaped pick-up

A bipolar primary pad topology for EV stationary charging and highway power by inductive coupling

Electric vehicles have been rapidly gaining in popularity in recent years, and with them inductive charging solutions. The ideal stationary charging system requires no input from the user, and places as few restrictions on either parking location, or environmental conditions (i.e. rain or snow) as possible. The success of inductive charging systems is contingent largely on the design of the magnetic coupling components; i.e. the track pad and the pickup. This paper details a new topology for the track pad, consisting of two largely coplanar, partially overlapping coils positioned such that there is no mutual inductance between them. This arrangement prevents interaction of the two coils, and allows the currents within them to be independent in both phase and magnitude. By controlling the phase and magnitude of the two coil currents, the magnetic field can be shaped to assist in power transfer to a pickup underneath an EV.

Investigation of Multiple Decoupled Coil Primary Pad Topologies in Lumped IPT Systems for Interoperable Electric Vehicle Charging

Today many vehicle manufacturers are interested in an inductive power transfer system design with a secondary side that is simple and low in cost, weight, and size. To achieve this, a more sophisticated primary side design is required to ensure interoperability with various magnetic topologies. Simple secondary pads such as the circular pad and double-D pad (DDP) (similar to the flat solenoid) can only couple either the perpendicular or parallel component of flux entering the surface of the pad respectively. This paper investigates using various known multiple coil pad designs as the primary that can be switched between various excitation modes during operation, without making tuning or other expensive adjustments. The primary pads considered here include; the DDP, the double-D quadrature pad (DDQP) and the bipolar pad (BPP). Results show that the mutually coupled structure of the DDP primary makes it a poor choice for interoperability, whereas the DDQP and BPP are able to achieve good results because of the decoupled coil structures inherent in their design. The DDQP has improved leakage characteristics while the BPP shows better interoperability characteristics with improved material usage efficiency and is easy to drive because of its identical coil structures.

A Bipolar Pad in a 10-kHz 300-W Distributed IPT System for AGV Applications

This paper presents the magnetic analysis of a recently proposed multiple coil pad design, called the bipolar pad (BPP), in a distributed inductive power transfer (IPT) system for automatic guided vehicle (AGV) applications. The paper briefly discusses the magnetic design optimization procedure and then optimizes another recently proposed secondary pad design (generally used in lumped IPT systems), called the double-D quadrature pad (DDQP), for distributed AGV applications and compares its performance with the BPP. A four conductor single phase track topology is used here as primary. Both the pads discussed in this paper have already been shown to perform well in lumped IPT systems and hence the work presented in this paper highlights and validates the possibility of using these pads in mixed distributed/lumped IPT systems. A 3-D finite element modeling tool is used to evaluate and compare all the models presented in this paper. To validate these results, a prototype system is built with a BPP secondary driving a load through a controller circuit. A modification in the traditional control topology is proposed and shown to improve the overall system efficiency; before finally highlighting some of the practical design issues needed to be considered when building such a system.

A bipolar receiver pad in a lumped IPT system for electric vehicle charging applications

Inductive Power Transfer (IPT) has proved its capability as a safe, convenient and efficient solution for electric vehicle (EV) charging systems by providing sufficient power levels with tolerance to lateral displacement. The magnetic design of the receiver/secondary and transmitter/primary pads is the most critical part of an IPT system design. This paper presents the performance of a Bipolar Pad (BPP) receiver in a lumped IPT system for EV charging systems and compares it against the performance of a recently proposed receiver design, Double-D Quadrature Pad (DDQP). A 3D finite element modeling tool, which has shown good agreement between measured and simulated results in the past, is used to simulate all the models presented in this paper. The prototype models are also built and tested to verify the simulated results. Although it has been shown that the polarized single sided flux pad design, Double-D Pad (DDP), has much better performance than the non-polarized single sided flux pad design, Circular Pad (CP), still the ability of a receiver pickup to interoperate with both types of transmitters is considered to be highly desirable. In this paper the performance of a BPP receiver is compared against the performance of a DDQP receiver when used with either a DDP transmitter or a CP transmitter. The results show that the BPP receiver approximately matches the output levels provided by a DDQP receiver while using less amount of copper. Finally, the possibility of improving the ability of both the BPP and DDQP receivers to interoperate with both DDP and CP transmitters by changing the receiver ferrite structure is investigated. The results however indicate that for both the BPP and the DDQP receiver designs, the traditional ferrite structure exhibits best material usage efficiency amongst the design possibilities considered in this paper.

A wireless power transfer system for low power electronics charging applications

This paper proposes the design, simulation and implementation of a wireless power transfer system utilising the concept of inductively coupled power transfer (ICPT). The magnetic structures of the system, the ICPT platform and pick-up, are custom-designed and simulated to enhance power transfer and efficiency through finite-element-method analysis software. Next, the ICPT platform, consisting of a single-layer of rectangular spiral arrays, was implemented on printed-circuit-board and the pick-up was constructed using ferromagnetic material. Overall, the prototype system was shown to induce a relatively uniform low-power across the ICPT platform, to justify the use of such a system in low-power inductive-charging electronics-applications.

Wavelet-based processing of ECT images for inspection of printed circuit board

This paper presents a wavelet-based image processing technique, which analyzes eddy-current testing (ECT) images derived by scanning printed circuit boards (PCBs) with an ECT probe and automatically detects the existence and location of the defect. First, the undesired components contained in probe output are removed through two types of wavelet filtering. Then the comparison of two images obtained from reference and tested PCBs are carried out to extract the signal due to the defect. In this paper, one-dimensional (1-D) wavelet is used only in the horizontal direction considering that the scanning of the probe is along that direction. In addition, the square norm of difference between original and processed signal is proposed as a criterion to keep the waveform of the defect peak as possible. The application examples of sample PCBs reveal the effectiveness and problems of the given approach.

An improved magnetic design for inductively coupled power transfer system pickups

This paper presents a new approach to the design of inductively coupled power transfer pickups using electromagnetic modeling techniques. As shown, significant improvements in the level of output power are able to be achieved for a given volume of ferrite by considering the field vectors in and around the ferrite and the power coil. The new design approach undertaken using 3-D simulations, is verified experimentally in the laboratory

Magnetic design of a 300 W under-floor contactless Power Transfer system

This paper presents a new magnetic design for an Inductive (contactless) Power Transfer system (IPT) suitable for Automatic Guided Vehicle (AGV) applications. A new receiver is introduced in this paper, called a Bipolar Pad (BPP) pickup. This IPT system is designed to operate at a frequency of 10 kHz and is intended for use in material handling industrial applications. 3D Finite Element Method (FEM) software is used to analyse and design this system to transfer up to 300W across an air gap of 30 mm. A tolerance of 150 mm to lateral displacement on either side of the centre of a single phase track, which uses four conductors, is possible.

Multiphase Inductive Power Transfer Box Based on a Rotating Magnetic Field

The industrial use of inductive power transfer (IPT) systems is becoming widespread, ranging from monorail systems, motors, people movers, and battery charging applications. This paper proposes a 3-D IPT system driven by a multiple-phase power converter. This is aided by spice circuitry simulation of the power converter, finite-element-assisted software magnetic frequency analysis, and via implementation of the proposed system. The proposed system consists of a cubic power transfer primary window generated by a rotating magnetic flux flow path. This rotating field is loosely coupled via magnetomotive force (MMF) induction into a secondary power pick-up. The system has been demonstrated as a low-power battery charging system.