BIDIRECTIONAL CURRENT-FED-HALF-BRIDGE (C)(LC)  (LC) CONFIGURATION FOR INDUCTIVE WIRELESPOWER  TRANSFER SYSTEM

 

Abstract

This paper contributes to analysis and development of a new power electronics system for bidirectional wireless power transfer. The major focus is analysis and implementation of a new current-fed resonant topology with current-sharing and voltage doubling features. A new bidirectional wireless power transfer system with current-fed half-bridge voltage doubler circuit is proposed and analyzed with series-parallel and series resonant networks. Traditionally used parallel L-C resonant tank in transmitter circuit with current-fed WPT topology causes higher voltage stress across the inverter devices to compensate the reactive power consumed by the loosely coupled coil. In the proposed topology, this is mitigated by adding a suitably designed capacitor in series with the transmitter coil thus developing a series-parallel CLC tank. Detailed analysis and design is reported for both, grid-to-vehicle and vehicle-to-grid operations. The power flow is controlled through variable frequency modulation. Soft-switching of the devices is obtained irrespective of the load current. A proof-of-concept experimental hardware prototype rated at 1.2kW is developed and tested. Experimental results are presented to verify the analysis and demonstrate the performance of the system with bidirectional power flow

EXISTING  SYSTEM:

Transmitter side parallel compensation with current source inverter (CSI) topologies is reported. The merit of parallel resonant tank is that the capacitor provides the required reactive power to the coil without flowing through the inverter switches. In addition, the parallel capacitor provides much lower impedance to the higher order harmonics and hence, the coil voltage and current profiles are almost harmonics free. However, at medium power level, the requirement of higher voltage rated inverter devices is a major limitation of transmitter side parallel LC tank. This is because the parallel capacitor alone provides high volume of reactive power consumed by the TC. To overcome this issue, in this paper, a new IPT topology with current-fed converter is proposed and analyzed. A capacitor is added in series with the TC to develop CLC tank that reduce the voltage stress across the inverter switches. Proposed IPT topology is capable of conducting bidirectional power, thus enabling both grid-tovehicle (G2V) and vehicle-to-grid (V2G) operations.   This is the first attempt to implement bidirectional IPT with current-fed topology with current-sharing voltage doubler configuration. This is an enhanced version of the paper presented in with additional results and detailed analysis and design. DC link inductor provides natural short circuit protection and also limits the peak and circulating current through the components. Current sharing (half-bridge) configuration further reduces the average and peak current through the components resulting into reduced conduction losses. Current-fed circuit also offers voltage gain and the voltage doubler add 2x additional gain. Proposed converter is analyzed and detailed design procedure is reported.

PROPOSED   SYSTEM:

Fig shows the proposed bidirectional IPT topology where  the transmitter side high-frequency (HF) inverter is current-fed half-bridge and receiver side HF rectifier is a voltage doubler. During G2V operation, i.e., EV battery recharging operation, the switches S1 and S2 are modulated while the switches S3 and S4 are kept permanently off. Compared with conventional parallel LC tank network, an extra capacitor is added in series with the TC to reduce the effect of high leakage of the coil to form CLC series-parallel resonant circuit. The detailed comparison of parallel LC and CLC tank network with the inverter as half bridge and full-bridge current-fed converter is presented.   An appropriate size capacitor is connected in series with receiver coil to compensate the reactive power consumed by the receiver coil. The series compensation network is most common in IPT application due to simple structure and load independent resonance. However, series compensation both in the transmitter and receiver sides leads to insatiably during no load condition. However, in this paper only the receiver side compensation is series LC type; therefore, this instability issue does not arise here. The detail design considerations of seriesseries  compensated IPT topology are elaborately described. During G2V operation the voltage doubler network is used as an uncontrolled rectifier whereas during V2G operation, this converter acts as an inverter. The voltage across and current through the switches are named as v S1  ~ v  ~ i , respectively and these signals for their body diodes are named as v S6 D1  ~ v D6  and i D1  ~ i , respectively.

CONCLUSIONS

The contribution and focus of this paper is to propose,  analyze, and develop a new power electronics system for wireless power transfer with G2V and V2G capability. A new current-fed topology with bidirectional ability and currentsharing  and voltage doubling features has been proposed. The proposed topology is analyzed with a new series-parallel CLC tank network. The proposed tank network reduces the device rating of grid side devices and permits the use of devices with low on-state resistance and cost compared to traditional series LC tank. Bidirectional inductive WPT is designed and developed using proposed current-fed circuit and CLC tank configuration. This is the first attempt to implement bidirectional IPT with current-fed circuit and CLC tank and demonstrate G2V and V2G operation. Keeping inverter output power factor lagging, soft-switching turn-on of the inverter switches is always ensured irrespective of load variation. Complete mathematical analysis and systematic design is reported. However, coils or magnetics design is not the focus of the paper. Experimental results verify the reported analysis and design and demonstrate the operation and performance.

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