Inductive Power Transfer Based on Variable Compensation Capacitance to Achieve an EV Charging Profile With Constant Optimum Load

Abstract

Wireless charging must be highly efficient throughout the entire battery charging profile to compete in the electric vehicle (EV) industry. Thus, optimum load matching is commonly used: it operates at the equivalent load that maximizes the efficiency, which depends on the coil's alignment. In this article, the optimum load is made independent of the coils' position by changing the system's resonant frequency through switch-controlled capacitors (SCCs). This eliminates the need for load-side voltage control. The output current follows the battery voltage rise during the battery charging cycle to always match the optimum load, which can be achieved by regulating the input voltage via the power factor correction (PFC) converter. This method is called here constant optimum load (COL). Two SCC topologies have been implemented in a 3.7-kW hardware demonstrator. The one implementing the half-wave modulation achieves higher efficiency than the one employing full-wave modulation, with 96.30% at 3.2 kW and aligned coils. When misalignment occurs, the half-wave modulation technique results in higher efficiency than the conventional-fixed compensation, where the efficiency is lower by up to 0.68% at partial load. Based on these results, the proposed COL method is proven suitable for 3.7-kW EV-static wireless charging achieving one of the highest peak efficiencies listed in today's literature for the same power class.

Fast dynamic control for a boost DC/DC converter in hybrid-electric powertrain with PEM fuel cell and battery pack

“…A proper modelling of the battery is essential for an accurate design of the anti-wind-up saturation limits of the regulators, and it is performed as suggested in [27,28]. Although a lithium-ion cell can be represented by several chemical [29,30], electric [31] or electro-chemical [32] models, for the aim of this paper it is straightforward to simplify the load by means of a variable voltage generator, where the battery voltage ranges from V batt,min = 37 V to V batt,max = 60 V with a…”

Modeling and Analysis of Wireless Power Transfer System Via Unified Full-Load Discrete-Time Model

“…And the pulsewidth and phase shift of the active rectifier can be applied to tune to achieve an impedance match [25], [26]. In addition, tuning the compensated capacitors can also impact the optimum load resistance, and the optimum load is made independent of the coils' position through switchcontrol capacitors [27]. The optimum load can be tracked by the closed-loop control to realize maximum efficiency.…”

Realization of an Optimum Load for Wireless Power Transfer System

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