Achieving misalignment tolerance with hybrid topologies in electric vehicle wireless charging systems

With the rocketing progress of wireless power transfer (WPT) for electric vehicles (EVs), the issue of misalignment tolerance has become increasingly vital, a hybrid topology of the series–series (S–S) and inductor–capacitor–capacitor-parallel (LCC-P) is proposed in this paper to achieve misalignment tolerance. Both the S–S topology and the LCC-P topology have constant-current output, the difference is that the output power of S–S increases with the increasing misalignment, oppositely, the output power of LCC-P reduces with the increasing misalignment. A combination of these two topologies can enhance the anti-offset capability. The magnetic couplers utilize unipolar (Q) and bipolar (DD) coils as the two decoupled coils for power transfer. The mathematical model has been established and analyzed. The transfer efficiency and the output parameters’ expressions of current, voltage and power have been derived. The theoretical analysis has been verified in the simulation model of MATLAB/Simulink. The proposed hybrid topology has succeeded in achieving misalignment tolerance

Reconfigurable topology of electric vehicle wireless power transfer system to achieve constant-current and constant-voltage charging based on multiple windings

In the wireless charging system of electric vehicles, different charging stages have different charging requirements, namely constant-current (CC) charging mode and constant-voltage (CV) charging mode. The purpose of this paper is to provide a multi-winding wireless charging system with a reconfigurable topology to realize CC and CV charging with different optimal load resistances so that high efficiency can be achieved over a large load resistance range. The designed system can form different compensation topologies by switching on and off relays, such as the series–series topology and the inductor–capacitor–capacitor-series topology. Different topologies have different optimal load resistances, therefore, it can realize efficient transmission in a large load resistance range. In addition, the half-bridge scheme and the full-bridge scheme are the other two functioning modes for each topology. At the same time, the efficiency of the system can reach up to 94.34% and 95.13% in the half-bridge as well as full-bridge schemes under the CC mode. The highest transmission efficiency can reach 93.37% and 90.78% for the half-bridge as well as full-bridge schemes under the CC mode, respectively. Experiment results have validated the proposed method

A metal object detection system for electric vehicle wireless charging with quadrupole detection coils

In the practical application of magnetic coupling wireless charging technology, the absence of direct contact between the receiver and transmitter usually leads to metal objects (MOs) entering the charging area. The strong magnetic field between the receiver and transmitter causes eddy current effects and generates large amounts of heat in MOs, which may lead to serious hazards such as fires, so it is necessary to detect accidental entry of MOs. In this paper, a novel detection coil layout suitable for wireless charging of electric vehicles (EVs) has been proposed, which consists of multiple quadrupole coils arranged to achieve decoupling from the receiver and the transmitter to minimize the effect on the system efficiency. The influence of the presence of MOs on the equivalent inductance and equivalent resistance of the quadrupole detection coil has been deduced. The simulation results show that the maximum self-inductance change rate of the proposed detection coil reaches 28.11%, and a high self-inductance variation rate is also achieved at the edge of the detection coil

A multi-channel wireless charging system with constant-voltage outputs based on LCC-S topology and integrated magnetic design

As an emerging technology, wireless power transfer (WPT) has various advantages, which can be enhanced by extending the WPT system into a multi-channel one. With the rapid development of electronic equipment, the demand for multiple independent voltage-source outputs is increasing. In many consumer electronics and industrial applications, voltage sources with multiple independent outputs are required. This paper proposes a wireless charging system with multiple constant-voltage (CV) outputs. The LCC-S (inductor capacitor capacitor-series) topology is adopted to achieve CV outputs. The output voltage can be regulated by the corresponding mutual inductance between the transmitting and receiving coils. The receiving coils are designed with overlapped areas to realize mutual decoupling, thus, each output voltage can be independent of each other. The compensating inductor is designed as a quadruple coil so that it can be integrated and decoupled with the transmitting coil at the same time, meanwhile, it can also be decoupled with the receiving coils. In this way, a multi-channel WPT system with independent CV outputs can be achieved. An experimental prototype with three CV output channels is implemented to validate the proposal. The experimental results have revealed that the three CV outputs can be stable with the load resistance variation in each channel