Inductive Charging Of Electric Vehicles Research Articles

Resonance Converter for Inductive Charging of Electric Vehicles; Modeling and Design

Resonance Converter for Inductive Charging of Electric Vehicles; Modeling and Design

Virtual Inertia-Based Multipower Level Controller for Inductive Electric Vehicle Charging Systems

A method of modulating the power level of a grid-supplied inductive electric vehicle (EV) charger to provide frequency stabilization to the utility grid is presented. The proposed controller can allow inductive EV charging systems to effectively respond to grid frequency fluctuations by online regulating the charging level and adding high virtual inertia. A new IPT multipower level controller using simplified digital circuits is designed. The virtual inertia control/controller (VIC) is incorporated into the proposed multipower level controller which gets the grid frequency measurement and online adjust the IPT’s charging level. Using the proposed VIC IPT charger, the switching cycles, as a result, the power transfer from the grid to the EV can be regulated in response to the grid frequency change. The simulation results of the proposed VIC IPT power controller are presented to show its effectiveness in response to power grid fluctuations. The proposed virtual inertia based controller is experimentally implemented and verified on an IPT setup connected to an actual small-scale Labvolt testbed.

Dealing with magnetization effects in EV positioning systems based on periodic magnetic signals

This paper presents the general solution to the accuracy problems in magnetic field based positioning systems needed for inductive charging of electric vehicles. These systems process a periodic magnetic signal emitted by the charging coil for its localization. The amplitude is highly distorted by the ferromagnetic vehicle according to an unknown transformation f. Thus, this paper discusses how f is affected by the magnetization process in the material. It is shown that f is proportional to the incremental permeability μΔ which depends on the non-deterministic operating point on the material’s hysteresis curve. However, in this research the same problem is described for the first time from the perspective of Hopkinson’s law, showing that the hysteresis curve is extremely flattened. As a consequence μ△ has in all possible operating points the same value, meaning that f is reproducible, measurable and depends only on the distance d to the coil. Further, it is deduced that f(d) is a strictly monotonously decreasing function, which enables unambiguous coil detection. Finally, the non-monotonous structure of f close to the coil is discussed, and why it is negligible for positioning.

Radar-based living object protection for inductive charging of electric vehicles using two-dimensional signal processing

As battery capacities become suitable for the mass market, there is an increasing demand on technologies to charge electric vehicles. Wireless charging is regarded as the most promising technique for automatic and convenient charging. Especially in publicly accessible parking spaces, foreign objects are able to enter the large air gap between the charging coils easily. Since the evoked magnetic field does not meet regulations, wireless charging systems are demanded to take further precautions related to the protection of endangered objects. Thus, additional sensors are required to protect primarily living objects by preventing them from being exposed to the magnetic field. In this paper, we propose a new approach for monitoring the air gap under the vehicle underbody using an automotive radar sensor on the vehicle side. The concept feasibility is evaluated with the help of a prototypical implementation. Further, two-dimensional signal processing techniques are applied to meet the requirements of inductive charging systems. Consequently, this paper provides measurement data for relevant use cases frequently discussed in the community of inductive charging.

Impact of dynamic and static fast inductive charging of electric vehicles on the distribution network

Fast inductive charging technologies allow the exchange of high power quantities (>20kW) between an Electric Vehicle and the electrical grid in contactless way. This demand can significantly modify the load profile of a distribution network and affect its operation and planning. Thus, it is necessary to quantify the grid impact of a network of fast inductive chargers and define the maximum allowable deployment level which does not violate the technical constraints of the network. This paper introduces a methodology for grid impact analysis of fast inductive charging technologies into distribution networks. The proposed methodology is implemented in a realistic model of a Greek MV distribution feeder providing indicative qualitative and quantitative results.

Radio Alignment for Inductive Charging of Electric Vehicles

To maximize power transfer for inductively charging electric vehicles (EVs), charger and battery coils must be aligned. Wireless sensors can be installed to estimate misalignments; however, existing ranging techniques cannot satisfy the precision requirements of the misalignment estimation. We propose a high-precision wireless ranging and misalignment estimation scheme, where high precision is achieved by iteratively measuring, estimating, and aligning the coils. Another key aspect is to convert the nonconvex misalignment estimation to a more tractable problem with a convex objective. We develop a conditional gradient descent method to solve the problem, which performs gradient descent (or conditional gradient descent on the boundary of the search space) and projects out-of-boundary points back into the space. Employing experimentally validated models, we show that our scheme can achieve 92% of the efficiency of perfectly aligned coils in 90% of operations, and tolerate correlated distance measurement errors. In contrast, the prior art is susceptible to correlation, undergoing a significant efficiency degradation of 18.5%.