Abstract
In a dynamic wireless power transfer (DWPT) system for electric vehicles, bipolar transmitting rail is often implemented to improve the misalignment tolerance, but its constraint often lies in fluctuating output. This problem can be mitigated by applying two-phase receivers which, due to its structural characteristics in the impedance matching circuit, bring two new problems: limited range of impedance matching and low efficiency. This paper aims to tackle the two problems by introducing a cascaded topology and its control method. Firstly, the conventional topology of the two-phase receiver is thoroughly analyzed theoretically concerning impedance matching range and efficiency model. Secondly, a cascaded bridgeless rectifier-Buck (CBRB) as impedance matching with 0~ ∞Ω matching capabilities is put forward. Besides, the independent two-channel structure is also introduced leaving the output current ratio the key to efficiency optimization. Thirdly, the control method for the proposed topology using heuristic current ratio by adopting online estimation via auxiliary measurement coils is presented. Finally, experiments are verified on a 20 kW DWPT platform and the proposed topology and control method can raise the transfer efficiency by 3.3% compared with the conventional topology.
Highlights
Electric vehicles (EVs) have been drawing attention in many fields recently due to the potential of environmental protection and substitution of fuel-based vehicles [1]
The associate editor coordinating the review of this manuscript and approving it for publication was Tariq Masood
According to the coils of power transmitter, Dynamic wireless power transfer (DWPT) systems can be divided into three types: long coil type [7]–[9], array coil type [10], [11] and bipolar type [12]–[14]
Summary
Electric vehicles (EVs) have been drawing attention in many fields recently due to the potential of environmental protection and substitution of fuel-based vehicles [1]. Wireless power transfer (WPT) has been studied intensively in order to improve the charging process and solve the problems mentioned above [2]. Dynamic wireless power transfer (DWPT), as a case of WPT, is proposed expecting the achieve continuous charging to extend the driving range of EVs and lighten the bulky batteries [3]–[6]. As the receiver moves along the bipolar rail, the mutual inductance of the coils varies in a wide range together with the load conditions. These varying parameters often lead to the fluctuation of the output power making it more difficult to achieve objectives such as constant current output. Coupling zeros points occur when there is only one receiver implemented on the secondary side
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