Field orientation based three‐coil decoupled wireless transmitter for electric vehicle charging with large lateral receiver misalignment tolerance

Abstract

A three-coil decoupled transmitter is developed for the inductive power transfer system of electric vehicle charging. The three-coil decoupled transmitter consists of three overlapping rectangular coils with magnetic mutual decoupling and is capable of overcoming large receiver lateral misalignment up to 20 cm. A current optimization method is advanced to derive transmitter coil currents for the multi-phase system that minimizes the coil loss through optimizing the current distribution among transmitter coils. The optimized current distribution reduces the maximum leakage flux by around 40% compared to the best alternative excitation method. The compensation strategy provides unity power factor for high-power transfer phases and allows a single set of compensation capacitors to be used regardless of receiver alignment. The three-coil decoupled transmitter is compatible with a typical three-phase inverter for industrial practical application, which halves the power electronic switches used with previous topologies. The simulation verification is performed at 3.3 kW, achieving 93.76% efficiency at perfect alignment and 92.54% efficiency at 20 cm misalignment. The experimental verification is implemented at 3.3 kW with 200 mm ground clearance, realizing a 92.97% efficiency at perfect alignment and 90.57% efficiency at 20 cm misalignment. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Biological and Medical Disturbances Due to Exposure to Fields Emitted by Electromagnetic Energy Devices—A Review

“…This consistency can be checked from the supervision of adjusted field values concerning the associated threshold. By following such a strategy, the various devices used by humans as WCT or operating in close proximity as IPT can be designed to reduce emitted EMF respecting threshold regarding BE in tissue, see e.g., [98,99].…”

Analysis and design for constant current/constant voltage multi‐coil wireless power transfer system with high EMF reduction

“…If Z q2 instead of Z q1 is assigned to be zero, then (18), (19), and ( 20) can be recalculated accordingly by using the same method.…”

“…In [10][11][12][13], multi-coil WPT systems, applying repeater or intermediate coils, have been proven to improve the transmission efficiency compared with the conventional two-coil systems [14]. In [15][16][17][18][19][20], the magnetic field distribution can be adjusted by controlling the current in each transmitter sub-coil in the multi-coil WPT systems in order to achieve high misalignment tolerance and low leakage magnetic field. In [18], a space vector-based excitation method was proposed in the bipolar transmitter pad FIGURE 1 The structure of the EQR transmitter WPT system.…”

“…In [18], a space vector-based excitation method was proposed in the bipolar transmitter pad FIGURE 1 The structure of the EQR transmitter WPT system. EQR, exciter-quadrature-repeaters; WPT, wireless power transfer and in [19] the current optimization method was developed for a three-coil decoupled transmitter. Both these methods in the multi-coil WPT systems allow the magnetic field to be oriented towards the receiver pad under lateral misalignment.…”

“…The main contributions of this paper are: (1) Loadindependent CC/CV charging and ZPA conditions can be achieved simultaneously for the lateral misalignment of ±150 mm and vertical misalignment of +20 mm by applying the proposed coil topology and associated capacitor design methodology, without closed-loop control based on the output voltage or current signal from the receiver side. (2) Only one inverter unit is needed and the currents on two quadrature repeater coils adjust based on the receiver pad position without excitation current control on the transmitter side as required in [15,[17][18][19]. This current adjustment effectively reduces the leakage magnetic field in the lateral misalignment cases.…”