voltage-fed full bridge inverter topology for inductive wireless … · 2018-06-17 · converter...

19
Voltage-fed Full Bridge Inverter Topology for Inductive Wireless Power Transfer Application Surendrakumaran U 1 , Alamelu Nachiappan 2 Department of Electrical and Electronics Engineering Pondicherry Engineering College Puducherry 605014 Email: [email protected] 1 , [email protected] 2 May 24, 2018 Abstract This paper presents wireless power transfer topology for consumer electronics and electric vehicle (EV) charging ap- plication. The main focus is given on high-frequency DCAC and AC-DC wireless power transfer stage where the inver- sion stage is Voltage-fed topology. The required resonance in transmitter side is (C) (LC) type and in the receiver-side series (LC) type. The proposed topology network reduces the inverter switch stress to half of the conventional topol- ogy. Capacitor in dc-link provides constant input voltage. The required hightransmitter coil (TC) current for air core coupled inductor circulates through parallel resonating ca- pacitor which reduces inverter switch current stress. Res- onant converter provides soft switching at device turn ON which reduces switching loss. Also, soft recovery at bridge rectier eliminates diode reverse recovery loss. The converter is analysed and simulated using PSIM 9.03. 1 International Journal of Pure and Applied Mathematics Volume 118 No. 24 2018 ISSN: 1314-3395 (on-line version) url: http://www.acadpubl.eu/hub/ Special Issue http://www.acadpubl.eu/hub/

Upload: others

Post on 06-Jul-2020

2 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

Voltage-fed Full Bridge InverterTopology for Inductive Wireless Power

Transfer Application

Surendrakumaran U1, Alamelu Nachiappan2

Department of Electrical and Electronics EngineeringPondicherry Engineering College

Puducherry 605014Email: [email protected], [email protected]

May 24, 2018

Abstract

This paper presents wireless power transfer topology forconsumer electronics and electric vehicle (EV) charging ap-plication. The main focus is given on high-frequency DCACand AC-DC wireless power transfer stage where the inver-sion stage is Voltage-fed topology. The required resonancein transmitter side is (C) (LC) type and in the receiver-sideseries (LC) type. The proposed topology network reducesthe inverter switch stress to half of the conventional topol-ogy. Capacitor in dc-link provides constant input voltage.The required hightransmitter coil (TC) current for air corecoupled inductor circulates through parallel resonating ca-pacitor which reduces inverter switch current stress. Res-onant converter provides soft switching at device turn ONwhich reduces switching loss. Also, soft recovery at bridgerectier eliminates diode reverse recovery loss. The converteris analysed and simulated using PSIM 9.03.

1

International Journal of Pure and Applied MathematicsVolume 118 No. 24 2018ISSN: 1314-3395 (on-line version)url: http://www.acadpubl.eu/hub/Special Issue http://www.acadpubl.eu/hub/

Page 2: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

1 INTRODUCTION

Wireless power transfer Research has increased signicantly since itspracticality in proven by many research works. WPT technologynds its application in electric vehicle, electronic gadgets, chemicalplants, lighting, and underwater vehicle applications. This tech-nology has huge potential to expand especially in electric vehicle(EV) [1] [2] market since it reduces the energy storage/distancelimitations of EVs and the charging process is very convenient tothe users. Because of these advantages, WPT technology can shiftthe gasoline-dependent vehicles to EVs with faster rate, hence lessdependent on petroleum and less environmental impact. Of thetwo nonradiation based WPT technologies, inductive power transfer(IPT) is suitable for both low and high-power applications, whereascapacitive power transfer (CPT) is suitable for lower power appli-cations [3]. Since, in EV, the charging power level is in kilowattlevel, IPT is preferred for EV charging applications. Fig. 1 showsa general power train of EV charging with IPT technology [4]. Thecrucial element in IPT system is coupled inductor where transmit-ter coil (TC) and receiver coil (RC) has an air gap of 150-300 mm.Effective power transfer is not possible by injecting normal powerfrequency voltage to TC since the coupling coefcient between TCand RC is very low. However, efcient power transfer is possible,if TC receives a voltage with its resonance frequency and RC res-onance frequency is tuned to same frequency [5] [6]. Because ofthe presence of large air gap, the overall efciencyin this system isslightly lower compared with conductive charging [7] [8]. SeveralIPT topologies based on different types of transmitter and RC res-onances are discussed in [2], [9][16]. Conventionally, the inversionstage is chosen as voltage source inverter (VSI) topology or matrixconverter topology [17]. In VSI topology, the transmitter-side seriesresonance is achieved by placing the capacitor in series. Since therequired reactive component of TC current ows through the VSIswitches, TC resonating network is modied as LCL network [2], [9].

2

International Journal of Pure and Applied Mathematics Special Issue

Page 3: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

Fig.1. Powertrain of wireless Power Transfer

voltage-fed inverter topology is also a viable solution for WIPTand this is the main focus of this paper. It reduces the currentstress through the devices which lead to reduced conduction lossesof the switches. In addition, the capacitor is located on transmitterside, which is stationary. Therefore, for some applications, increasein weight or slight increase in volume for one stationary componentmight not be a major issue. In-build short-circuit protection is anadded benet for this application. Inverter operates at very highfrequency; hence, the inductor size is small. The cost of induc-tor is generally higher. For such reasons, voltage-fed topology isalso a possible solution. In voltage-fed topology, parallel resonancein the TC is achieved by placing capacitor across the coil. Sincethe reactive current of a voltage-fed resonant converter circulatesinside the parallel resonant tank without owing through the switch-ing network, the current rating ofthe switching devices is smallerand the conduction loss is reduced for a given power level . Also,TC current in this topology is almost pure sinusoidal since parallelcapacitor provides much lower impedance than the TC. In spiteof these advantages, the implementation of Voltage-fed topology inhigh-power IPT application did not get much attention [16]. Themajor limitation of this topology is that the voltage stress on in-verter switches are high, especially when the load power is highand it becomes worse when coefcient of coil coupling is lower. Inthis paper, a new IPT topology with inversion stage as voltage-fedtopology is presented. The required resonance network in transmit-ter side is (C) (CL) type and the receiverside resonance network is

3

International Journal of Pure and Applied Mathematics Special Issue

Page 4: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

series type. Along with all other advantages of voltage-fed con-verter in IPT application, lower voltage stress across the inverterswitches is also achieved with the capacitor in series with the TC.

2 IPT USING VOLTAGE-FED TOPOL-

OGY: ANALYSIS AND DESIGN

A. IPT With Conventional Voltage-Fed InverterWhere the inversion stage is VSI topology are discussed [18]. Sincethe input of the VSI is constant voltage, parallel resonance/compensationin TC coil is achieved by placing a capacitor C parallel to the TC.In the receiver side, the compensation is either parallel or seriestype. TC current It is almost pure sinusoidal even though the in-verter output Voltage V inv p is a square wave. However, the majorlimitation of this circuit is the high-voltage stress on VSI switchesspecially when the required load power is high and the couplingbetween TC and RC is low. It is because the TC due to a bulkamount of reactive power when the required load power is high andcoefcient of coupling is relatively low. Since this high amount ofreactive power is produced by the parallel capacitor, the voltage ofthe capacitor increases and eventually appears across VSI switches.This limitation of the circuit is resolved by adding a capacitor inseries with TC.

Fig.2. Circuit diagram of Voltage-fed wireless power transferTopology

4

International Journal of Pure and Applied Mathematics Special Issue

Page 5: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

B. Proposed IPT Circuit With Lower Voltage Stress ofVSI Switches

Fig. 2 shows the complete circuit diagram of proposed voltage-fed IPT converter. The input dc voltage V d can be either a dcsupply mains or the output of a power factor corrected (PFC) rec-tier. To convert this dc to high-frequency ac, a voltage-fed invertertopology is used where the CapacitorC transforms stiff current Idto stiff voltage V as shown in Fig. 2. Considering that switchingfrequency of VSI is sufciently high and the Capacitor Cdis sufcientlylarge, the VSI injects a square wave voltage Iinv to next transmit-ter resonant network stage. Because of air core, the value of themutual inductance M is much lower than the conventional iron corecoupled inductor. Hence, to transfer a signicant amount of activepower through the air, the required TC current has to be highenough such that sufcient amount of voltage in the RC(ωMIt) isinduced. In this topology, a capacitor Cpt is added in Parallel withthe TC; hence, the effective impedance of the coil is reduced andparallel capacitor Cp needs to deliver lesser reactive power thanthe conventional circuit. To reduce the VSI switch current stress,the selection of the capacitors C pt and Cs has to be such that thereactive component of the TC current circulates through Cpt pt andVSI switches supply only the active component of current. The pur-pose of the series diodes [D1, D2, D3, D4] is to prevent short circuitof capacitor C through switches and body diodes of the switches.For example, when switches S1 and S4 are ON and if the voltageacross C is negative, then there is a short-circuit path of C throughS4 - S2 body diode. However, if the inverter output voltage andcurrent are in same phase, then there is no need of these seriesdiodes. But in practical, circuit parameters change and mutual in-ductances vary; hence, power factor deviates from unity. Thus, theseries diodes are mandatory. Reverse voltage blocking insulatedgate bipolar transistors (IGBTs) (RB-IGBT) are suitable optionfor this topology. However, considering the switching loss of theIGBTs at higher switching frequency and also considering the lackof availability of reverse blocking IGBTs for wide voltage range,MOSFET-diode combination is used at this stage.

A series capacitor C is connected to achieve the required reso-nance in RC. Thus, the large voltage drop across the RC leakageinductor Lsr is compensated. Next, diode bridge recties the RC

5

International Journal of Pure and Applied Mathematics Special Issue

Page 6: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

current and feeds the battery.C. Proposed IPT Circuit With Lower Voltage Stress of

VSI Switches

The parallel-parallel compensation topology is also a viable so-lution for WPT. However, parallel topology in the receiver sidesuffers from circulating current [19] and this leads to higher cop-per loss in the RC. Also, parallel compensation on the receiver sideleads to inductive lter after the diode bridge rectier. This will in-crease on-board charger weight as well as needs secondary snubbersto limit ringing and diode voltage stress. The switches S1 and S4, adiagonal pair, are modulated by identical gating signals. Similarly,other diagonal pairs of switches S2 and S3 are triggered by identicalgating signals. The key message is that all four devices cannot beOFF at a time. Only one diagonal pair is turned OFF at a time topass the current from source to the coils; otherwise, all four devicesare

Fig.3. PWM pulses for Proposed WPT

ON during overlap allowing the inductor to store the energy. Itis similar to boost converter principle. Referring to Fig. 2 whenswitching signal S1 is high, capacitor Cd always gets a continuouspath irrespective of the status of S2. Similarly, when S1 is low, i.e.,S1 is high, Cd always gets a continuous path. Calculation of circuitparameters and the voltage and current stress of the componentsare derived here.

6

International Journal of Pure and Applied Mathematics Special Issue

Page 7: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

D. Design of Compensation CapacitorApplying Kirchhoffs current law (KCL) at inverter output, the in-verter current is given as

Iinv = It + Ic (1)

where It is TC current; Ic is capacitor Cp, current. Replacingthe currents with branch voltage and impedance, (1) is modied as

Iinv =

Vinv + jωMIr

jωL1 +1

jωCs

+ jωCpVinv (2)

=

[ω2MCsIrω2L1Cs − 1

]+ j

[ωVinv(Cp −

Csω2L1Cs − 1

)

](3)

where L1 is self-inductance of TC,ω is the angular frequency, Mis mutual inductance, Ir is RC current, and TC-to-RC turns ratiois 1:1. From Fig. 3, it is clear that without parallel capacitor Cpthe required high amount of TC current would pass through VSIswitches. The magnitude of VSI output current is minimized byselecting CptandCst such that second part of (2) is removed. Onthe receiver side, voltage injected at the input of the diode bridgeis given as

VrD = jωMIt − Ir[jωL2 +

1

jωCr

](4)

where Csr is receiver-side series compensation/resonance capac-itor. The value of Csris chosen such that bridge input voltage VrD ismaximum which is done by removing the second part of (3). From(2) and (3), required capacitances are calculated as

ωt =1√

L1

(CpCsCp + Cs

) , ωr =1√CrL2

(5)

Effective power transfer is achieved by equalizing VSI switching fre-quency ωs(= 2πfs), TC resonance frequency ωt, and RC resonancefrequency ωr

7

International Journal of Pure and Applied Mathematics Special Issue

Page 8: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

E. Derivation of Switch Voltage and Current RatingIn order to simplify the calculation, coil resistance and switch lossesare neglected which is reasonable since voltage drop across coil ismainly due to its inductance. It is clear that the reverse blockingvoltage rating of the diodes D5, D6, D7, and D8 are the same asbattery voltage Vb. The current waveform of the RC is sinusoidalsince it passes through the series resonating circuit. Hence, thepeak and RMS current rating of the diodes are given as

ID =π

4I0, ID =

π

2√

2I0 (6)

where I0 is average battery charging current. Transmitterside switchand diode current rating are the same as dc-link Capacitor Cd. Peakforward-blocking voltage of the switches or reverse voltage-blockingvoltage of the series diodes are dependent on peak voltage of ca-pacitor Cpt voltage.The active load, i.e., battery is replaced by itsac equivalent voltage Veq. Since the internal resistance of recharge-able battery is in the order of milliohm or fraction of ohm, and thevoltage drop across it is much less when compared with the batteryvoltage, it is not included in the derivation. Although Veq wave-shape is square wave, only its fundamental component is involvedin active power transfer, since current Ir is sinusoidal. It is clearfrom Fig. 3 that IrandVeq are in same phase, since the receiver-sidediode bridge toggles the conduction of diode pairs just after thechange of polarity of Ir. In order to derive the voltage and currentstress on circuit components, consider that the current Ir or voltageVeq is reference phasor. Applying power balance and using Fourieranalysis, RMS value of equivalent load voltage and RC current arederived as

Veq =2√

2

πVo, Ir =

π

2√

2I (7)

Applying Kirchhoffs voltage law (KVL) in the receiverside loop, TCcurrent is calculated as

It = −j 2√

2

π

V0ωsM

(8)

Applying KVL and KCL in transmitter side and using (6) and (7),RMS value of voltage across TC and voltage across series capacitor

8

International Journal of Pure and Applied Mathematics Special Issue

Page 9: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

Cs is derived as

Vt =2√

2

π

L1

MVo − j

π

2√

2ωsMI0 (9)

Vcs = −2√

2

π

V0ω2sCsM

(10)

Applying KVL, RMS value of inverter output voltageVinv is cal-culated by adding (8) and (9) and applying KCL, inverter outputcurrent is calculated as

Vinv =2√

2

π

V0ωsM

(ωsL1 −

1

ωsCs

)− j π

2√

2ωsMIo (11)

Iinv =π

2√

2ω2sMCpIo − j

2√

2

π

V0CpM

X

(1

ωsCs+

1

ωsCp− ωsL1

)

(12)From (10) and (11), power factor at the inverter output is derivedas

cosφ = cos(φi−φv) = cos

tan

−1

π2

8R0

ω2sM2(

ωsL1 −1

ωsCs

)

− tan−1

{8R0

π2

1

ω2sM

2

(1

ωsCst+

1

ωsCpt− ωsL1

)}

(13)From (12), it is clear that if CptandCst are selected using (4), thenthe power factor at inverter output is leading and it gives softswitching at device turn OFF of inverter switches. Hence, the par-allel capacitor Cpt is calculated using (12) such that at rated outputpower, inverter output is slightly lagging which enables soft switch-ing at device turn ON. This modied value of capacitor Cpt for softswitching at device turn ON is slightly lower than value calculatedusing (4). From (10) and (11), VSI peak switch voltage and bothpeak and RMS current ratings are derived as

Vsw = Vinv ≈4

π

V0ωsM

(ωsL1 −

1

ωsCst

)Isw =≈ π2

8ω2MCptI0 (14)

In order to calculate natural voltage gain of the dc-dc wireless powertransfer stage, volt-sec balance is applied on the dc inductor Ld.

9

International Journal of Pure and Applied Mathematics Special Issue

Page 10: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

Average voltage (VA) at the input side node of Ld is same as inputdc voltage V . Average voltage at the other side d of inductor, i.e.,H-bridge inverter side is calculated as

VB =1

π

∫ π+φ

φ

Vinv .sinω t.dt =2√

2

πVinv cosφ =

8

π2

V0ωsM

X

(ωsM −

1

ωsCs

)cosφ (15)

At steady state, both node voltages of inductor are same, i.e., VA= VB . Hence, natural voltage gain of dc-dc wireless power transferstage is calculated using (14) as

V0Vd

=π2

8

ωsM

cosφ

1(ωsL1 −

1

ωsCs

) (16)

From (15), it is clear that without presence of series capacitor Cs ,the voltage gain of the converter would be

V0Vd

=π2

8

1

cosφ

M

L1

(17)

Hence, another advantage of the proposed converter is improvedvoltage gain compared with conventional parallelseries compen-sated topology. In order to describe steady-state operation of onefull switching cycle with all subintervals, the capacitor Cp is selectedusing (12) such that the inverter output power factor is lagging.

F. Steady state operation for one complete switchingcycle IntervalInterval 1 [t0 − t1 − t2]: Consider that at time instant t0, diagonalswitch pair of the inverter S1 and S4 are inconduction are shown inFig.3. Also consider that the inverter output voltage, Vinv leads theinverter output current, Iinv. During time interval,t0tot1 switchesS1 and S4 take the complete inverter current and off-diagonal switchpair S3 and S4 blocks a voltage with same magnitude as inverteroutput voltage, Vinv. The receiver coil current, Ir is positive duringthe interval t0tot1 and diode pair D5, D8 conducts and feeds theoutput lter capacitor, Co . At time instant t2 receiver coil current,

10

International Journal of Pure and Applied Mathematics Special Issue

Page 11: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

Ir changes its direction and diode pair D6, D7 commutates and D5,D8 start conduction.Interval 2 [t2 − t3 − t4]: At time instant t2 inverter output voltage,Vinv changes its direction since, the operating power factor at theoutput of the inverter is considered as lagging. At time instant t3gating signal of switch pair S3 and S2 become high but since, thevoltage across these switches are negative, the other switch pair S1and S4 keeps on conducting are shown in Fig.3. A negative voltagewith same magnitude as Vinv appears across the switch diode pairs(S3, D3 and S2, D2) and the diodes D5 and D2 blocks this negativevoltage. Throughout this time interval t2 − t3 − t4 receiver sidediode pair D6, D7 conducts.Interval 3 [t4− t5]: At time instant t4 gating signal of switch S1 andS4 is removed and immediately switch S3 and S2 takes the invertercurrent. It is clear that to get the zero voltage switching, time lagof inverter output current, Iinv from output voltage Vinv has to beequal or more than the overlap time of the switches. The switchpair S3 and S2 keep on conducting in the interval t4tot5 and theswitch pair S1 and S4 keep on blocking the positive voltage. Atthis interval rectier diode pair D6, D7 in the receiver side keeps onconducting. Interval 4 [t5 − t6 − t7 − t8]: At instant t5 receiver coilcurrent, Ir Changes its direction and diode pair D5, D8 conductsand feeds the output lter capacitor, C0. At instant t6 inverter out-put voltage,Vinv changes its direction and at time instant t7 gatingsignal of switch pair S1 and S4 becomes high but since, the voltageacross these switches are negative, the switch pair S3 and S2 keepson conducting. At time instant t8 gating signal of switch S3 andS2 is removed and immediately switch S1 and S4 takes the invertercurrent and this cycle repeats in every switching cycle.

3 WIRELESS PAD AND COIL DESIGN

While designing a wireless IPT system then main factor is Magneticcoupling. Generally, Inductive pads are classied as inductive padwithout ferromagnetic core and IPT pad with ferromagnetic core,i.e., IPT pad with ux-guided material. Although the IPT pad withferrite core is comparatively expensive, it has some advantages.

11

International Journal of Pure and Applied Mathematics Special Issue

Page 12: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

The major advantage of the ferrite core is that it minimizes themagnetic eld emissions around the coils by reducing the stray orfringe elds since ferrites keep the magnetic eld in between the coils.Various types of ux-guided IPT pads are discussed in [9], [12], [20]and [21][26]. Since the main objective of this paper is to examinethe suitability of the proposed Voltage-fed topology in IPT, a UU-type core is selected for its simple structure and easy to implement.Considering that the main focus of this paper is power electronicsand control and not on IPT couplers; hence, detail design is notcarried out here. The coil design and size optimization of the padsare detailed in [20] and [25].The change in self-inductance of IPT pad is very slow with changein pad misalignment, whereas the change in mutual inductance ismuch faster. It is clear that for the ux generated due to currentow in TC have two possible ux paths. One is through transmittercore - air-transmitter core and the other one is through transmittercore - air - receiver core - air-transmitter core. The reluctance ofthe second parallel ux path, i.e., via receiver core increases with theincrease in air gap between TC and RC. Hence, this slight reductionin TC self-inductance with increase in air gap is observed. Also,increase in air gap directly leads to increase in reluctance to themutual ux; therefore, mutual inductance reduces with increase inair gap [18], [27].The predominant loss in these large air gap coils is the copper loss.From TC current and RC current expressions given in (6) and (7),the copper loss in the coils is calculated as

Pcul =8

π2X

(V0ωsM

)2

r1 (18)

Pcul =π2

8XI20r2 (19)

where r1 and r2 are transmitter and RC ac resistances,respectively.Using (17) and (18), the coil-to-coil efciency is calculated as

ηcoil =1

1 +8

π2

V0

I0 (Mωs)2 r1 +

π2

8

I0V0r2

(20)

From (19), it is clear that coil-to-coil power transfer efciency in-creases with increase in impedance due to mutual coupling (Mωs)

12

International Journal of Pure and Applied Mathematics Special Issue

Page 13: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

and reduction in coil ac resistance. For a given system, all param-eters in (19) other than charging current are known. Hence, theoptimum charging current for maximum coil-to-coil power transferefciency and corresponding maximum efciency are given as

V0 =π

8Mωs

(r1r2

)2

I0max (21)

I0max =8

π2

V0Mωs

√r1r2

(22)

ηcoilmax =1

1 + 2

√r1r2Mωs

(23)

4 SIMULATION RESULTS

The WPT circuit shown in Fig. 2 is simulated using PSIM 9.03.Simulation model for power ratings rated at 630 W was developed.The main application of the proposed converter is EV; therefore,to demonstrate the feasibility of the concept for high power, theproposed converter is simulated for 630-W power output. The IPTpad parameters, viz. self-inductances and mutual inductance valuesfor 630-W system are selected from [7]. In order to control batterycharging current, xed switching frequency and variable duty cyclemodulation is adopted in the inverter. The current ratings of theinverter switches are almost same, whereas the voltage rating ofthe proposed topology is close to half of the conventional LC reso-nance tank network. Hence, the inverter VA rating is also almosthalf. Fig. 4 shows steady-state voltage and current waveforms oftransmitter and RCs for 630-W power transfer. Equations (6) and(7) show that TC current It lags RC current Ir by 90 degree. Also,from (8), TC voltage Vt lags Ir . Since the mutual inductance isvery low, the real part of (8) predominantly determines the voltagemagnitude. Fig. 4 veries this analytical prediction. With the givensimulation parameters, calculated RMS value of Vt is 512 V for 630-W power output. Simulation result also gives the same value of Vt.Fig.4 shows that the TC voltage and current waveforms are veryclose to sinusoidal. It is because the parallel capacitor Cp provides

13

International Journal of Pure and Applied Mathematics Special Issue

Page 14: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

much lesser impedance to higher order harmonic currents than TC,and the TC predominantly receives fundamental component.

Fig. 5 shows the simulation results of the different voltagewaveforms of the passive elements of transmitter-side tank network.Since the impedance of the capacitor Cs is half of the impedance ofTC self-inductance at resonance frequency, hence, parallel capaci-tor Cp gets approximately half of the TC voltage Vt as derived in(8), (9), and (10). Simulation

Fig.4. Simulation results: Steady-state waveforms of TC voltagevt current it, and RC voltage vr and current ir

Fig.5. Simulation results: Steady-state waveforms of gating signal

14

International Journal of Pure and Applied Mathematics Special Issue

Page 15: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

of switch S1, inverter output voltage vinv, series capacitor voltagevcs and TC voltage

results given in Fig. 5 verify this mathematical analysis. Thisis a major advantage of this topology where the inverter switchesget half of the TC voltage stress, whereas the switch voltage stressis exactly similar to TC voltage in case ofconventional voltage-fedtopology. Fig. 6 shows steady-state dc input voltage, input cur-rent waveforms and dc output voltage, output current waveformsfor 630-W power output, and Fig. 6 shows voltage and currentwaveforms at diode bridge rectier ac input for 630-W output, re-spectively.

Fig.6. Steady-state waveforms for Output voltage vb and currenti0 and Diode bridge rectier input voltage vrD and current id

Table I Selected simulation parameters

15

International Journal of Pure and Applied Mathematics Special Issue

Page 16: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

5 CONCLUSION

A new inductive wireless power transfer circuit using Voltage-fedconverter is presented in the paper. This topology provides an al-ternative wireless power transfer solution for EV charging. Simula-tion results show that the required voltage in the transmitter coil issupplied by the parallel compensation capacitor. Capacitor in theseries of the transmitter coil reduces voltage rating of the inverterswitches. Soft switching at turnon of VSI switches ensures lowerswitching loss. Also, soft recovery of the rectier diodes eliminatesreverse recovery loss. All the analysis and simulation are veriedusing PSIM.

References

[1] D. H. Tran, V. B. Vu, and W. Choi, Design of a High EfciencyWireless Power Transfer System with Intermidiate Coils forthe Onboard Chargers of Electric Vehicles, IEEE Transactionson Power Electronics, vol. 8993, no. c, pp. 11, 2017.

[2] S. Li and C. C. Mi, Wireless power transfer for electric vehicleapplications, IEEE Journal of Emerging and Selected Topicsin Power Electronics, vol. 3, no. 1, pp. 417, 2015.

[3] W. Eberle and F. Musavi, Overview of wireless power transfertechnologies for electric vehicle battery charging, IET PowerElectronics, vol. 7, no. 1, pp. 6066, 2014.

[4] U. Surendrakumaran and Alamelu Nachiappan., Performanceanalysis of wireless power transfer(WPT) through two-coil andthree-coil structure, in 2017 International Conference on In-novative Research In Electrical Sciences (IICIRES), pp. 16,IEEE, jun 2017.

[5] S. Samanta, A. K. Rathore, and D. J. Thrimawithana, Bidirec-tional Current-Fed Half-Bridge (C) (LC)(LC ) Conguration forInductiveWireless Power Transfer System, IEEE Transactionson Industry Applications, vol. 53, pp. 40534062, jul 2017.

[6] A. Kurs, A. Karalis, R. Moffatt, J. D. Joannopoulos, P. Fisher,and M. Soljacic, Wireless power transfer via strongly coupled

16

International Journal of Pure and Applied Mathematics Special Issue

Page 17: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

magnetic resonances., Science, vol. 317, no. 5834, pp. 836,2007.

[7] O. C. Onar, J. Kobayashi, D. C. Erb, and A. Khaligh, A bidi-rectional high-power-quality grid interface with a novel bidi-rectional noninverted buck-boost converter for PHEVs, IEEETransactions on Vehicular Technology, vol. 61, no. 5, pp.20182032, 2012.

[8] S. Dusmez and A. Khaligh, A charge-nonlinear-carrier-controlled reduced-part single-stage integrated power electron-ics interface for automotive applications, IEEE Transactions onVehicular Technology, vol. 63, no. 3, pp. 10911103, 2014.

[9] H. H. Wu, A. Gilchrist, K. D. Sealy, and D. Bronson, A highefciency 5 kW inductive charger for EVs using dual side con-trol, IEEE Transactions on Industrial Informatics, vol. 8, no.3, pp. 585 595, 2012.

[10] A. P. Hu, J. T. Boys, and G. A. Covic, Frequency Analysisand computation of a current-fed resonant converter for ICPTpower supplies, PowerCon 2000 - 2000 International Confer-ence on Power System Technology, Proceedings, vol. 1, pp.327332, 2000.

[11] U. K. Madawala and D. J. Thrimawithana, A bidirectionalinductive power interface for electric vehicles in V2G systems,IEEE Transactions on Industrial Electronics, vol. 58, no. 10,pp. 47894796, 2011.

[12] P. Ning, J. M. Miller, O. C. Onar, C. P. White, and L. D. Mar-lino, A compact wireless charging system development, Con-ference Proceedings - IEEE Applied Power Electronics Confer-ence and Exposition APEC, pp. 30453050, 2013.

[13] H. L. Li, A. P. Hu, and G. A. Covic, A direct AC-AC converterfor inductive power-transfer systems, IEEE Transactions onPower Electronics, vol. 27, no. 2, pp. 661668, 2012.

[14] D. J. Thrimawithana and U. K. Madawala, A novel matrixconverter based bi-directional IPT power interface for V2G

17

International Journal of Pure and Applied Mathematics Special Issue

Page 18: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

applications, 2010 IEEE International Energy Conference andExhibition, EnergyCon 2010, pp. 495500, 2010.

[15] J. Shin, S. Shin, Y. Kim, S. Ahn, and S. Lee, Design and Im-plementation of Shaped Magnetic Resonance Based WirelessPower Transfer System for Roadway-Powered Moving ElectricVehicles, no. c, pp. 1 14, 2013.

[16] R. Huang and B. Zhang, Frequency, impedance characteris-tics and HF converters of two-coil and four-coil wireless powertransfer, IEEE Journal of Emerging and Selected Topics inPower Electronics, vol. 3, no. 1, pp. 177183, 2015.

[17] S. Samanta and A. K. Rathore, Analysis and design of current-fed (L)(C) (LC) converter for inductive wireless power transfer(IWPT), in 2015 IEEE Energy Conversion Congress and Ex-position (ECCE), no. L, pp. 57245731, IEEE, sep 2015.

[18] J. Kan, S. Xie, Y. Tang, and Y. Wu, Voltage-fed dual activebridge bidirectional DC/DC converter with an immittance net-work, IEEE Transactions on Power Electronics, vol. 29, no. 7,pp. 35823590, 2014.

[19] N. A. Keeling, G. A. Covic, and J. T. Boys, A unity-power-factor IPT pickup for high-power applications, IEEE Trans-actions on Industrial Electronics, vol. 57, no. 2, pp. 744751,2010.

[20] J. Shin, S. Shin, Y. Kim, S. Ahn, S. Lee, G. Jung, S.-J. Jeon,and D. H. Cho, Design and Implementation of Shaped Mag-netic Resonance Based Wireless Power Transfer System forRoadway-Powered Moving Electric Vehicles, IEEE Transac-tions on Industrial Electronics, vol. 61, no. 3, pp. 11791192,2014.

[21] M. Budhia, G. A. Covic, and J. T. Boys, Design and optimiza-tion of circular magnetic structures for lumped inductive powertransfer systems, IEEE Transactions on Power Electronics, vol.26, no. 11, pp. 30963108, 2011.

[22] C. Park, S. Lee, G. H. Cho, and C. T. Rim, Innovative 5-m-off-distance inductive power transfer systems with optimally

18

International Journal of Pure and Applied Mathematics Special Issue

Page 19: Voltage-fed Full Bridge Inverter Topology for Inductive Wireless … · 2018-06-17 · converter topology [17]. In VSI topology, the transmitter-side series resonance is achieved

shaped dipole coils, IEEE Transactions on Power Electronics,vol. 30, no. 2, pp. 817827, 2015.

[23] M. Budhia, J. T. Boys, G. A. Covic, and C. Y. Huang, Devel-opment of a single-sided ux magnetic coupler for electric ve-hicle IPT charging systems, IEEE Transactions on IndustrialElectronics, vol. 60, no. 1, pp. 318328, 2013.

[24] Z. N. Low, R. A. Chinga, R. Tseng, and J. Lin, Design andtest of a high-power high-efciency loosely coupled planar wire-less power transfer system, IEEE Transactions on IndustrialElectronics, vol. 56, no. 5, pp. 18011812, 2009.

[25] S. Y. Choi, B. W. Gu, S. Y. Jeong, and C. T. Rim, Advances inwireless power transfer systems for roadway-powered electricvehicles, IEEE Journal of Emerging and Selected Topics inPower Electronics, vol. 3, no. 1, pp. 1836, 2015.

[26] A. Khaligh and S. Dusmez, Comprehensive topological analy-sis of conductive and inductive charging solutions for plug-inelectric vehicles, IEEE Transactions on Vehicular Technology,vol. 61, no. 8, pp. 3475 3489, 2012.

[27] U. R. Prasanna and A. K. Rathore, Small-signal modelingof activeclamped ZVS current-fed full-bridge isolated DC/DCconverter and control system implementation using PSoC,IEEE Transactions on Industrial Electronics, vol. 61, no. 3,pp. 12531261, 2014.

19

International Journal of Pure and Applied Mathematics Special Issue