Wide-scale adoption and projected growth of electric vehicles (EVs) necessitate research and development of power electronic converters to achieve high power, low-cost, and reliable charging solutions for the EV battery. This paper presents a comprehensive review of EV off-board chargers that consist of ac-dc and dc-dc power stages from the power network to the EV battery. Although EV chargers are categorized into two types, namely, on-board and off-board chargers, it is essential to utilize off-board chargers for dc fast and ultra-fast charging so that volume and weight of EV can be reduced significantly. Here, we discuss the state-of-the-art topologies and control methods of both ac-dc and dc-dc power stages for off-board chargers, focusing on technical details, ongoing progress, and challenges. In addition, most of the recent multiport EV chargers integrating PV, energy storage, EV, and grid are presented. Moreover, comparative analysis has been carried out for the topologies and the control schemes of ac-dc rectifiers, dc-dc converters, and multiport converters in terms of architecture, power and voltage levels, efficiency, bidirectionality, control variables, advantages, and disadvantages which can be used as a guideline for future research directions in EV charging solutions. 

/pdf/a-comprehensive-review-of-power-converter-topologies-and-8o9fuuyc.pdf

A Comprehensive Review of Power Converter Topologies and Control Methods for Electric Vehicle Fast Charging Applications

Inductive power transfer (IPT) technologies have gained a wide acceptance in onboard battery charging applications due to some significant advantages over traditional plug-in systems. An IPT battery charger is expected to provide a configurable charging profile consisting of an initial constant current (CC) and a subsequent constant voltage (CV) efficiently. With a wide load range during the charging process, two sets of IPT topologies with the inherent load-independent CC and CV at the same zero-phase angle (ZPA) frequency are commonly combined into a hybrid topology to avoid sophisticated control schemes, while maintaining nearly unity power factor and soft switching of power switches simultaneously. However, the load-independent CC and CV are usually constrained by parameters of a loosely coupled transformer (LCT), making the LCT hard to design. To solve it, this paper systematically presents a method to derive such effective hybrid IPT converters, which starts from some existing topologies having the configurable CC or CV output and cascades a general T network for mode transition. Design principles with fewer mode switches and compensation components are proposed and some available hybrid topologies regardless of the constraint of LCT parameters are given in this paper. Control logic and sensitivities of compensation parameters to the input impedance and the load-independent output are also discussed. Finally, a 1 kW hybrid IPT battery charger prototype based on LCC-LCC and LCC-S topologies is built to verify the theoretical analysis.

Hybrid Inductive-Power-Transfer Battery Chargers for Electric Vehicle Onboard Charging With Configurable Charging Profile

Wide-scale adoption and projected growth of electric vehicles (EVs) necessitate research and development of power electronic converters to achieve high power, low-cost, and reliable charging solutions for the EV battery. This paper presents a comprehensive review of EV off-board chargers that consist of ac-dc and dc-dc power stages from the power network to the EV battery. Although EV chargers are categorized into two types, namely, on-board and off-board chargers, it is essential to utilize off-board chargers for dc fast and ultra-fast charging so that volume and weight of EV can be reduced significantly. Here, we discuss the state-of-the-art topologies and control methods of both ac-dc and dc-dc power stages for off-board chargers, focusing on technical details, ongoing progress, and challenges. In addition, most of the recent multiport EV chargers integrating PV, energy storage, EV, and grid are presented. Moreover, comparative analysis has been carried out for the topologies and the control schemes of ac-dc rectifiers, dc-dc converters, and multiport converters in terms of architecture, power and voltage levels, efficiency, bidirectionality, control variables, advantages, and disadvantages which can be used as a guideline for future research directions in EV charging solutions.

https://ieeexplore.ieee.org/ielx7/6287639/6514899/09755960.pdf

Traditional Class-E circuit features fewer components, high reliability, and soft switching. However, due to the unidirectional excitation, the application of such a topology circuit is limited, i.e., usually used in low-power applications. To relieve this issue, this article proposes a switched-capacitor-based Class-E circuit, to extend the operating power range of the Class-E circuit. With the proposed new circuit, both constant current (CC) and constant voltage (CV) output modes can be achieved by switching the branch once without changing the switching frequency or compensation network. Compared with the existing CC and CV charging strategies, the proposed circuit has the advantages of fewer components, simpler implementation, and higher reliability. Moreover, the studied compensation network can also be extended to other inverter topologies. The working principle of the proposed circuit is described in detail, and the variable zero-voltage switching (ZVS) margin is introduced to make an accurate design of parameters. Subsequently, the influence of high-order harmonic components on the circuit and the sensitivity of parameters are analyzed. Finally, the proposed circuit is simulated and experimented on a 180–450-W prototype with CC and CV characteristics to verify the feasibility of the circuit and the accuracy of theoretical analysis.

A Hybrid Class-E Topology With Constant Current and Constant Voltage Output for Light EVs Wireless Charging Application

Inductive power transfer (IPT) is an attractive wireless power charging option in many applications such as electric vehicle biomedical devices and consumer electronics, etc. Constant current and constant voltage (CC-CV) charging profile is widely used for charging applications due to affecting the life and the reliability of the Li-ion battery. However, the IPT systems that can achieve both CC and CV modes with soft switching are not well studied. This paper presents an inductive power transfer system for wireless charging without a back-end converter, which achieves the required two-stage charging profile with high efficiency by keeping inverters’ soft switching operation. The characteristics of an LCC-S compensation topology have been investigated thoroughly. Two fixed resonant frequencies, whose analytical expressions have been derived, can be found to realize constant current output and constant voltage output respectively under zero-phase angle condition. Besides, an effective tuning method has been presented for zero voltage switching realization to reduce the switching loss. Moreover, a parameter design procedure has been summarized for the wireless charger with a simplified structure and high efficiency. Finally, the method is validated through experiments on a 3.5kW prototype realizing constant current and constant voltage outputs with a peak efficiency of 97.3%.

/pdf/a-novel-design-method-of-lcc-s-compensated-inductive-power-psc7l7vesz.pdf

A Novel Design Method of LCC-S Compensated Inductive Power Transfer System Combining Constant Current and Constant Voltage Mode via Frequency Switching

Inductive power transfer (IPT) systems have many unique benefits compared to conventional plugged-in systems. The coupling pads in IPT systems are inevitably misaligned in many practical applications, thus leading to variations of the transferred power and efficiency that necessitate the use of complicated control for output regulation. A common solution is to use two IPT converters with opposite trends of output to pad misalignment, so that the total output voltage or current could be kept near constant for large coupling variations. However, methods for deriving effective configurations for such hybrid IPT converters and their achievable tolerance to the misalignment are still missing. This article constructs a family of hybrid IPT topologies, including input-parallel–output-parallel, input-parallel–output-series, input-series–output-parallel (ISOP), and input-series–output-series for delivering a constant current (CC) or a constant voltage (CV). Design principles and characteristics for all the hybrid systems with near load-independent output and high tolerance to pad misalignment are derived and discussed in detail. Based on this family of configurations, this article also combines some existing IPT topologies and derives multiple hybrid converters for CC or CV output by using a simple duty cycle control. Finally, a 3.5-kW hybrid IPT prototype converter based on the ISOP structure is built to verify the theoretical analysis.

A Family of Hybrid IPT Topologies With Near Load-Independent Output and High Tolerance to Pad Misalignment

The inductive power transfer (IPT) technology has gained a wide acceptance in battery charging applications due to its significant advantages over traditional plug-in systems. It is desirable that an IPT charger can be configured with the initial constant current (CC) and the subsequent constant voltage (CV) outputs as the battery requires, combating constr-aints of the loosely coupled transformer (LCT) parameters without sophisticated control schemes. Meanwhile, a near resistive input impedance and soft switching for the whole battery charging process can be permitted. To meet these requirements, this paper systematically analyzes the characteri-stics of some existing compensation topologies and proposes two hybrid IPT structures to realize the configurable CC and CV outputs in regardless of the constraints of LCT parameters. Due to the different output filters, a hybrid IPT battery charger, actually using the combination of the doublesided LCC and LCC-S compensation circuits, is proposed and implemented in this paper. Finally, an experimental prototype is built to validate the proposed design.

Dule Wang

Papers

A Family of Hybrid IPT Topologies With Near Load-Independent Output and High Tolerance to Pad Misalignment

Hybrid Inductive-Power-Transfer Battery Chargers for Electric Vehicle Onboard Charging With Configurable Charging Profile

Design of an IPT Battery Charger with Configurable Constant Current and Constant Voltage Outputs