Automatic tuning concept for a three-phase inductive power transfer system

Abstract

Contactless charging of electric vehicles by means of inductive power transfer is becoming increasingly popular in the recent years. In contrast to wired power interfaces, userfriendly and secure wireless links with no physical contact are preferable. Especially in the higher power range (>100kW), three-phase approaches are an encouraging alternative to singlephase systems due to great EMC benefits. While compensation of single-phase systems is comparatively simple, the static tuning procedure is much more complex for three-phase systems. Aggravating, system parameter drifts arising from slightly mismatched positioning and thermal influences shift the systems current working point away from the optimal one for which the whole system is tuned statically. As an essential base, in a first part this paper introduces an appropriate approach for the static tuning of a three-phase system and discusses the effects of parameter drifts on the pickup. Based on the static tuning, concept ideas for an automatic retuning of the pickup during operation are presented in the second part.

Review of inductively coupled power transfer for electric vehicle charging

“…The frequency splitting of a two-coil resonator separates into odd and even frequencies, which are Norton's theorem simplifies the circuit by representing one value of total impedances parallel to a current source which is the short circuit current across two selected nodes [82] Thevenin's theorem simplifies the circuit by representing one value of total impedances series to a voltage source which is the open circuit voltage of two selected nodes [83] Kirchhoff's voltage law (KVL) the algebraic sum of all voltage drops in the closed-loop circuit is equal to zero [54,84] Kirchhoff's current law (KCL) the sum of all currents entering and leaving of one node is equal to zero [61] superposition theorem circuit analysis on voltage and current across each impedance for each power source case. Then, the voltage and current impedance value is the algebraic sum of all cases of the power source [7,10,[85][86][87] two-port network (ABCD) represents the network, excluding load and power source, as 'ABCD' matrix. Each letter represents the ratio of input or output voltage or current in two test conditions, short-circuit test and open-circuit test [88][89][90][91] two-port network (Sparameter)…”

Switched-Capacitor Tuning for Three-Phase Wireless Power Receiver Based on Perturbation and Observation Method

“…On the other hand, the output voltage under the resonance state is the maximum when the receiver's induction voltage and load are constant. Therefore, while keeping the transmitter working state, coupling relationship, and load state unchanged, the perturbation and observation (P&O) method (also called the hill-climbing method) can be used to determine whether the resonance has been achieved by observing the output voltage of receivers [20,21]. The concept of tuning the three-phase system by the P&O method also can be found in [21].…”

“…Therefore, while keeping the transmitter working state, coupling relationship, and load state unchanged, the perturbation and observation (P&O) method (also called the hill-climbing method) can be used to determine whether the resonance has been achieved by observing the output voltage of receivers [20,21]. The concept of tuning the three-phase system by the P&O method also can be found in [21]. However, only simulation analysis is performed in the paper, and physical experiment verification and analysis of actual application characteristics (such as adjustment effect and speed) are lacking.…”

Model and Frequency Control for Three-Phase Wireless Power Transfer System

“…Most of the previous research is limited in single-phase WPT system. With rapid development of electrical equipment, the three-phase WPT system has been further developed [7][8][9]. A new three-phase and bidirection WPT system that is suitable for rapid charging of EVs is presented [10].…”