Power Conversion and Signal Transmission Integration Method Based on Dual Modulation of DC-DC Converters

Transcription

1 IEEE TRANSATIONS ON INDUSTRIAL ELETRONIS 1 Power oversio ad Sigal Trasmissio Iegraio Mehod Based o Dual Modulaio of D-D overers Jiade Wu, Member, IEEE, Ji Du, Sude Member, IEEE, Zhegyu Li, Seior Member, IEEE, Yihua Hu, Member, IEEE, hogwe Zhao, Sude Member ad Xiagig He, Fellow, IEEE Absrac For he developme of commuicaio sysems such as Iere of Thigs, iegraig commuicaio wih power supplies is a aracive soluio o reduce supply cos. This paper preses a ovel mehod of power/sigal Dual Modulaio (PSDM, by which sigal rasmissio is iegraed wih power coversio. This mehod akes advaage of he irisic ripple iiiaed i swich mode power supplies as sigal carriers, by which a cos-effecive commuicaios ca be realized. The priciples of PSDM are discussed ad wo basic dual modulaio mehods (specifically PWM/FSK ad PWM/PSK are cocluded. The key pois of desigig a PWM/FSK sysem, icludig opology selecio, carrier shape ad carrier frequecy are discussed o provide heoreical guidelies. A pracical sigal modulaio-demodulaio mehod is give ad a prooype sysem provides experimeal resuls o verify he effeciveess of he proposed soluio. Idex Terms Power elecroics, power lie commuicaio, power/sigal dual modulaio, pulse widh modulaio, disribued power sysem. I I. INTRODUTION ew coceps such as he Iere of Thigs [1-3] ad he Idusrial Iere [4-5], machie-o-machie commuicaio is he backboe of fuure idusrial ad civil elecrical sysems, cosequely is receivig exesive aeio. A large umber of smar higs or objecs icludig faciliies, equipme, devices ad sesors ed o be coeced o fuure elecrical sysems, ad he big daa produced by hem is rasmied, sored ad aalyzed [6]. This brigs challeges o make hese elecrical sysems more iellige ad reliable. Mauscrip received Jauary 27, 214; revised April 24, 214; acceped Jue 13, 214. opyrigh (c 214 IEEE. Persoal use of his maerial is permied. However, permissio o use his maerial for ay oher purposes mus be obaied from he IEEE by sedig a reques o pubs-permissios@ieee.org. This work is sposored by he Naioal Naure Sciece Foudaio of hia ( ad ( J. Wu, J. Du,. Zhao, ad X. He are wih he ollege of Elecrical Egieerig, Zhejiag Uiversiy, Hagzhou 3127, hia ( eewjd@zju.edu.c; eeduji@zju.edu.c; zcwxp@yahoo.com.c; hx@zju.edu.c. Z. Li is wih he Elecrical, Elecroic ad Power Egieerig of he Aso Uiversiy, Birmigham, U.K. ( z.li@ieee.org. Y. Hu is wih he Deparme of Elecroic & Elecrical Egieerig, Uiversiy of Srahclyde, Glasgow, UK. ( Yihua.hu@srah.ac.uk I mos of radiioal Disribued orol Sysems (DS, commuicaio circuiry ad power supply circui are separaely desiged, so wo idepede circuis are eeded. For example, i disribued power supply sysems, addiioal commuicaio circuis are added o receive corol isrucios from a supervisor coroller or o exchage daa bewee power coverers [7-1]. O he oher had, for commuicaio odes i classic field bus sysems, such as RS-485 or AN, dedicaed power coverers are required o provide a sable power supply [11-12]. To simplify he wire coecio of he sysem, wo echiques are adoped [13-27]. The firs echique is wireless commuicaio, which has bee widely used ad icreasigly acceped for idusrial corol sysems [13-15]. However, due o he lack of physical proecio, he securiy ad reliabiliy of wireless eworks are ofe doubed, ad oher mehods have bee proposed for proecio [16-17]. O he oher had, for mos idusrial sysems, he odes of wireless eworks mus be powered, so hey ieviably coec wih he power supply by wires. The secod echique which simplifies coeciviy is Power Lie ommuicaio (PL, which origiaes from he so called secod idusrial revoluio [18-2]. The idea of rasmiig a sigal o a baery powered cable was used i he Lodo Liverpool elegraph sysem, which was he earlies record of iegraig he sigal rasmissio hrough power cables [18]. Sice he 192 s, he iveio of carrier frequecy rasmissio (TS ad ripple carrier sigalig (RS echiques has made PL a opio for remoe load corol. By he lae weieh ceury, wih he developme of iegraed circuis ad he Iere, cosiderable progress has bee made i modulaio mehods ad is applicaio scope [19]. Nowadays, PL echiques cover boh he high volage rasmissio eworks ad medium/low volage disribuio eworks, which ca supply services such as voice rasmissio, iere access, remoe meer readig ad load corol, over he power cable. The PL chael model has bee comprehesively ivesigaed [2-21], wih umerous applicaios repored [22-27]. This echique has proved a reliable mehod for commuicaio. However, boh wireless commuicaio ad PL require idepede circuis o amplify he commuicaio sigal. For PL, exra iducive or capaciive couplig uis are required o embed he daa sigal io he power lie, which icreases sysem coss ad volume.

2 Power oupu/ommuicaio chael Power ipu Power ipu IEEE TRANSATIONS ON INDUSTRIAL ELETRONIS 2 I [28-29], he auhors prese a ovel mehod ha realizes power lie commuicaio bewee D-D coverers which share a commo ipu D bus. Because he commuicaio sigal is iherely geeraed by he pulse widh modulaio of D-D coverers, here is o eed for a addiioal power amplifier o ijec he sigal o o he D bus. This cofirms he possibiliy of iegraig commuicaios io power coversio. However, hese researchers maily focus o sigal processig, ad he irisic relaioships bewee he power elecroic circui ad he commuicaio model are o ivesigaed. This paper preses a power/sigal dual modulaio (PSDM mehod o iegrae daa rasmissio wih power coversio. The commuicaio model ad he mehods of modulaio/demodulaio are aalyzed i deail. The proposed echique of PSDM embeds a commuicaio sysem io a power supply sysem, ad is a cos-effecive way o realize local commuicaios for some power sysems. This paper is orgaized as follows. The PSDM priciple is preseed ad aalyzed i Secio II. The applicable codiios, icludig opology choices ad modulaio mehods are discussed i Secio III. Modulaio ad demodulaio mehods are show i Secio IV. Prooype desig ad experimeal verificaio are show i Secio V. Fially, coclusios are give i Secio VI. II. PRINIPLE OF POWER/SIGNAL DUAL MODULATION I power elecroics, power coverers are cosruced wih semicoducor swiches ad passive elemes such as iducors ad capaciors. Pulse widh modulaio (PWM is he mos popular sraegy employed i he corol of power coverers. For he ypical PWM waveform show i Fig.1, he Fourier coefficies are f V T dt T T Fig.1 A ypical PWM waveform. (1 f ( a a cos( b si( a 1 1 dv (2 2V a si( d cos(2 d (3 2V b si( d si(2 d ( V c a b si( d (5 where is he agular frequecy of he waveform, d is he duy raio associaed wih period T, is he delay ime raio of he pulse, which correspodig o he agular compoe of he harmoics. For coveioal pulse widh modulaed circuis, he duy cycle d of each period is corolled o achieve a give average volage which correspodig o he D compoe of equaio (1. Alhough beig filered, he high frequecy harmoic compoes, wih iiial ampliude represeed by (5, sill exis a he ipu ad oupu pors. For a PWM sysem here are hree freedoms ha ca be maipulaed. Excep he duy cycle d used by PWM, he frequecy f ad phaseca be modulaed o carry iformaio, which correspod o he Frequecy-Shif Keyig (FSK ad Phase-Shif Keyig (PSK modulaio i sigal commuicaios. So ha PWM/FSK or PWM/PSK dual modulaio ca be employed o simulaeously realize power coversio ad sigal rasmissio, which is also ermed power/sigal dual modulaio (PSDM. Ipu overer Driver Power modulaio + PID - FSK modulaio Daa f1 f2 Oupu Fig.2 Block diagram of PWM/FSK dual modulaio. FSK modulaed carrier Drivig Sigal T 1 Fig.3 Drive sigal of PWM/FSK dual modulaio. This paper focuses o PWM/FSK modulaio ad does o pursue PWM/PSK. Fig.2 shows he block diagram of a PWM/FSK dual modulaed sysem. Differe from coveioal PWM, he carrier of he PSDM sysem is a FSK regulaed PWM sigal. A PWM/FSK modulaed waveform is show i Fig.3, where he circui operaes a frequecy f while sedig daa, ad frequecy f 1 while sedig daa 1. The ripples i he ipu ad oupu por waveforms carry iformaio ha has bee modulaed, o which a commuicaio sysem depeds. III. APPLIABLE ONDITION AND OMMUNIATION MODELING A. Srucure of he PSDM sysem Sedig Daa Sedig Daa PSE1 overer Received Daa PSE2 overer Received Daa Pah of Power rasmiig T 1 Demodulae Demodulae D Bus Sigal pah from Sigal pah from PSE1 o PSE2 PSE2 o PSE1 (a Load spliig srucure of a PSDM sysem.

3 Power oupu Power oupu Power ipu/ommuicaio chael IEEE TRANSATIONS ON INDUSTRIAL ELETRONIS 3 D Bus Demodulae Demodulae overer Received Daa PD2 Pah of Power rasmiig Sigal pah from PD1 o PD2 PD1 overer Received Daa Sedig Daa Sedig Daa Sigal pah from PD2 o PD1 (bsource spliig srucure of a PSDM sysem. Fig. 4 Two basic srucures of a PSDM sysem. The basic srucure of coveioal disribued power sysems icludes parallelig, cascadig, load spliig, source spliig ad sackig [3], which are also available for power/sigal dual modulaio sysem. I his paper, we defie wo fudameal devices: Power Sourcig Equipme (PSE ad a Powered Device (PD. PSE is a coverer ha commuicaes a he oupu while PD is a coverer ha commuicaes a he ipu. The srucure of load spliig is show i Fig.4(a while source spliig is show i Fig.4(b. The differece bewee hese wo srucures is he chael of commuicaio, source spliig lies i he ipu while load spliig lies i he oupu. B. Topology aalysis for PSDM Theoreically, all swichig mode D-D coverers ca creae addiioal high frequecy volage sigals a heir ipu or oupu, which could be used as a sigal carrier. The addiioal volage sigal i he coverer por icludes wo compoes, swichig oise ad swichig ripple. Swichig oise is sesiive o circui desig ad he placeme of swichig compoes, so is difficul o uilize. Swichig ripple is he volage geeraed by coverer ripple curre, ad is sable whe he circui compoe values are deermied. The volage ripple equals he produc of curre ripple ad por equivale impedace. For basic dc-dc opologies such as buck ad boos coverers, i is difficul o predic he curre ripple ampliude if he circui operaes i a discoiuous coducive mode (DM, because he curre ripple is sesiive o he load. So i his paper, all aalysis is based o sychroous recificaio (bidirecioal curre flow o preve DM. To achieve reliable commuicaios, he carrier should be sable i magiude, bu for some power elecroic opologies, he ripple is vulerable o he variaio of ipu volage ad oupu load. Therefore, he applicable operaig codiios of each dc-dc opology should be assessed. I a buck coverer (Fig.5, he ipu curre is pulsaive (always discoiuous ad is ampliude is deermied by he load, which meas ha he sigal carrier is usable so he buck coverer is usuiable for a PSDM-PD device. However, he oupu curre of he buck coverer is coiuous ad he ripple ampliude (Δi=U o (1-dT s /L is load idepede. The basic harmoic ampliude of he oupu curre ripple is UTs UTs I 1 si( d Sa( d I 2 1max Sa( d dl L (6 where U is he oupu volage, T s is he period, L is iducace. For a volage regulaed buck coverer, assumig he ipu volage varied from 1.3U o 3U, he duy cycle d chages from.33 o.77 while I 1 varies from.83i 1max o.27i 1max, which is accepable for sigal commuicaio. From his aalysis, i ca be cocluded ha he buck coverer is suiable for PSE, bu o for PD. Similarly, he ipu curre of boos coverer is coiuous, ad he ripple magiude (Δi=U d dt s /L is idepede of load, while is base frequecy ampliude is UT I1 s si( d I 2 1max si( d (7 L For a volage regulaed boos coverer if d varies from.3 o.7, he oupu ripple I 1 chages from.81i 1max o I 1max. However, he oupu curre of a boos coverer is pulsaive, ha is discoiuous. Therefore he boos coverer is suiable for PD, bu o PSE. The discussio i followig secio is based o he boos coverer, which operaes as a PD. Ud Ud i d Q1 Q2 L R U i d dts TS dts TS Fig.5 Buck coverer ad is curre ripple. L Q1 Q2 i T R dts TS U dts TS Fig.6 Boos coverer ad is curre ripple. Exedig he aalysis o oher dc-dc coverer opologies, he applicable suiabiliy codiios (coiuous por curre ca be obaied, as summarized i Table. I. TABLE. I APPLIABILITY OF TOPOLOGIES overer opology PD PSE Buck Usuiable Suiable Boos Suiable Usuiable Buck-Boos Usuiable Usuiable uk Suiable Suiable Sepic Suiable Usuiable Zea Usuiable Suiable. Shape of he modulaed carrier I a power/sigal dual modulaed coverer, alhough power coversio ad sigal modulaio are realized by a uified circui, he corol process of hese wo fucios should be decoupled, which meas he sigal modulaio should o affec he process of power coversio (ad vice versa. Assume ha a boos coverer operaes i a PWM/FSK dual modulaio mode, sawooh wave is employed as carrier (givig sigle ed modulaio, as show i Fig 7(a. Before - i T DiL DiL

4 IEEE TRANSATIONS ON INDUSTRIAL ELETRONIS 4 he swichig frequecy shifs from f 1 o f 2, he average curre is i AV1, ad he peak o peak curre ripple is 1, he he curre a he frequecy shifig poi is 1 dud il ( s iav1 DiL1 iav1 (8 2 2Lf1 where U d is he coverer ipu volage. Afer he swichig frequecy shifs o f 2, assumig he duy cycle remais he same, he peak o peak curre ripple is dud DiL2, so he average curre is Lf 2 1 dud 1 1 iav 2 il ( s DiL2 iav1 ( (9 2 2L f1 f2 The average curre differece before ad afer frequecy shifig is dud 1 1 DiAV iav 2 iav1 ( (1 2L f1 f2 Because he average oupu curre i oe swichig cycle is i T (AV=(1-di AV, he frequecy shifig will produce a curre perurbaio eve if he duy cycle remais cosa, as show i Fig.7(a. Therefore, embeddig FSK modulaio wih a sawooh carrier will iroduce addiioal ierferece, which should be avoided i he desig of he PSDM sysem. us1 f1 f2 D. ommuicaio model Take boos circui as a example, Fig.8(a shows a sysem composed of hree odes. V bus is a commo bus which is o oly for powerig he ode bu also for daa commuicaio. E 1 is a volage source which supplies power o V bus via a impedace sabilizaio ework Z r, which is comprised of a LR ework. The fucio of he iducor L r i he ework is o block he ierferece ad impedace from he volage source E 1, where L r complies wih 2 fl 1 r Rr (11 2 fr where f is he swichig frequecy. The capacior r i he ework is used o sabilize he bus, resisor R r is he equivale series resisace (ESR of r. Impedace sabilizaio ework Zr Lr Lr E1 r Rr r Rr Vbus i1 + M u1 L1 U - 1 Rs1 Impedace sabilizaio ework Zr Vbus L1 i1 D Bus/ ommuicaio chael i2 + L2 M u2 2 U - Rs2 Rs3 Node1 Node2 Node3 (a Sysem srucure. D Bus/ ommuicaio chael L2 i2 i3 + L3 M u3 3 U - L3 i3 ur s E1 1 Rs1 2 3 us1 us2 us3 Rs2 Rs3 ug iav Di (a Sawooh carrier r R r V bus Node1 Node2 Node3 (b Replace boos circuis by pulse volage sources. D Bus/ ommuicaio chael i 1 i 2 i 3 us1 f1 f2 R s1 R s2 R s3 ur ug iav s Di= (b Triagle carrier Fig.7 Waveformsof he Boos circui employig differe carrier. I Fig.7(b, a riagle wave is employed as a carrier (producig double edge modulaio. The swichig frequecy shifs from f 1 o f 2 o modulae he ieded sigal. Whe he swichig frequecy is f 1, he average curre is i AV1, he peak o peak curre ripple is 1. Afer he swichig frequecy shifs o f 2, he peak o peak curre ripple is du Di 2 d L, he Lf2 average oupu curre i oe swichig cycle remais he same, as show i Fig.7(b. Accordig o his aalysis, i is cocluded ha a riagle wave is a beer carrier opio. Node1 Node2 Node3 (c Simplified model for commuicaio. Fig.8 ommuicaio model of a boos-based sysem. The equivale series resisace of a boos coverer ipu capacior, represeed by R s13, cao geerally be igored. I seady sae, he swich ad oupu capacior of he boos circui is equivale o a pulse volage source from he poi of view of sigal commuicaio (Fig.8 (b. Igorig he dc compoe, he pulse volage source ad he iducor ca be replaced by a riagle curre source, so he diagram of he commuicaio sysem is simplified o Fig.8(c. Wihou cosiderig rasmissio lie resisace, whe odes are o he bus, he magiude of he ripple volage o V bus is V bus ( j k k1 I ( j jr jk 1 jr 1 jr r r k1 sk k (12 Whe several odes are coeced o he bus, he waveform o he bus is he liear syhesis of he ripple produced by each ode.

5 IEEE TRANSATIONS ON INDUSTRIAL ELETRONIS 5 IV. MODULATION AND DEMODULATION METHOD All he odes i a PSDM sysem produce oise sigals if hey do o sed a daa sigal, which is differe from radiioal PL echiques. Assume ha he daa carrier ad oise are deployed i he same specrum of he chael, accordig o he Shao heory of chael capaciy, he maximum commuicaio rae which a sysem ca be realized is deermied by Blog 2(1 SNR (13 where B is he commuicaio chael badwidh ad SNR is he sigal o oise raio. I a PSDM sysem of odes, assumig oe ode is sedig ad he ohers are waiig, he ampliude of eiher he sigal or oise is equal, so he chael capaciy of he bus ca be express as B Blog 2(1 SNR Blog 2(1 (14 1 Equaio (14 shows ha he commuicaio rae decreases as he umber of odes icreases, o he codiio ay sigal or oise is filered wihou ay discrimiaio. However, he equaio (14 resricio ca be overcome if a dedicae filer removes he oise frequecy compoe. I a biary frequecy shif keyig (BFSK based PSDM sysem, wo sraegies ca be uilized o rasmi he daa sigal. The firs is a hree-carrier sraegy: a carrier of frequecy f om is adoped whe a ode is waiig for commuicaio, carrier f is applied as sedig sigal ad carrier f 1 is applied as sedig sigal 1, such ha carriers shif bewee hree frequecies. The secod is a wo-carrier sraegy: carrier f om is adoped whe waiig for sedig daa or sedig sigal 1, carrier f is applied as sedig sigal. I his sraegy, he carriers shif bewee wo frequecies. For a PSDM sysem, he carrier frequecies f ad f 1 should be seleced as close as possible o f om o avoid adverse coverer effecs, such as sabiliy ad filer desigig problems. However, he closer he frequecies, he more difficul o differeiae hem. Assume ha N odes are o he bus ad oly oe ode is rasmiig sigal, he base frequecy of he bus ripple is s A cos 2 f A cos 2 f (15 1 om 1 where A 1 is he oise sigal ampliude ad A is he ampliude of daa sigal. A 1 is he syhesis of (N-1 waiig odes ad he value is variable because he carrier phase i every ode is differe. Assumig i a period T s, (15 is wrie as a complex Fourier series: s j2 k / Ts X ( k e (16 k To calculae he ampliude of he sigal f, i requires f m / T s m f s (17 where m is a ieger ad f s is he Fourier rasform frequecy, which meas f is he m h harmoic of he base frequecy f s. The ampliude of he sigal f is 1 Ts j2 m / Ts A X ( m s( e d T (18 s To elimiae he ifluece of frequecy f om, i should be Ts j2 m / Ts fom 1 e d (19 cos 2 I ca be iferred ha f om should comply wih fom m / Ts = m fs ( m is a ieger (2 This coclusio meas ha he oise ad sigal frequecies are differe harmoics of he base frequecy f s, which are orhogoal i he Fourier rasform period. Such a commuicaio priciple is ofe used i he echiques such as Orhogoal Frequecy-divisio Muliplexig (OFDM ad Miimum Shif Keyig (MSK. To miimize he frequecy differece of he sigal ad oise, i is assumed ha m m 1, or 1 f fom f (21 TS If a hree-carrier sraegy is adoped, he frequecy f 1 should be 1 f fom f1 (22 TS I his paper, he wo-carrier sraegy is employed because he swichig frequecy differece is smaller ha ha wih he hree-carrier sraegy. To guaraee he daa commuicaio rasparecy, he radiioal bye-based serial commuicaio mehod is adoped, which adds a ad 1 a he begiig ad ed of he bye, respecively. I he receiver, ripple sigals pass hrough a low-pass filer o remove high-order harmoics before i coecs o a AD chael of a DSP. The cu-off frequecy f of he low-pass filer ad he samplig ime f smp should comply wih he Nyquis heorem, or f 2 f (23 smp Assume N is he sample umber i a Fourier rasform period ad is specified by N f T (24 smp Fig.9 shows he relaioship bewee sample frequecy, oise frequecy, ad sigal frequecy. Noise Sigal Sample sequece S T S=1/ f S f om=m f S f =m f S f smp=n f S Fig.9 Waveforms of sigal i a Fourier rasform period. The ripple sigal sampled by he DSP is sored sequeially i memory, ad he he DSP execues a discree Fourier rasformaio (DFT afer each sample. The geeral DFT equaio is Leig W e N 1 2 j k N X ( k x( e ( k,1,..., N 1 (25 2 j K N, he compoe of f is N 1 X X ( K x( W (26 K Assume ha he curre DFT value is based o he sequece {x(, x(1, x(n-1}, ad he ex sequece is based o {x(1,

6 IEEE TRANSATIONS ON INDUSTRIAL ELETRONIS 6 x(2, x(n}, a ieraive mehod of slidig DFT ca be employed [31], ad he ew DFT value afer he ex sample ca be expressed as N1 N * 1 K ( 1 =( ( 1 X x W x W W 1 (27 [ X K x( x( N] W Eq.(27 decreases he DFT calculaio ime sigificaly, which makes i possible o execue he DSP DFT algorihm i every A/D sample period. Assume ha he effecive sigal received by each ode is x( Aom cos(2 fom [1 c( ] A cos(2 f c( (28 where 1 (if sedig bi '' c ( (o daa or sedig bi '1' The waveform shifs from f om o f whe c( chages from 1 o a, ad a widow fucio g( is defied as 1 ( Ts g ( (29 ( or Ts Assume he period of a bi is more ha T s, he resul of slidig samplig is x(, x(, { Aom cos(2 fom [1 c( ] (3 A cos(2 f c( } g( The f compoe of x(, is j2 f X ( x(, e d K T s { A cos(2 f ] c( om om j2 m / Ts A cos(2 f c( } e d The ampliude of X k ( ca be iferred T s X ( [ A cos(2 f K om om j2 m / T s A cos(2 f ] c( e d if c(, ( Ts Ts A 2Aom ( A + 2 T s m m c( 1 ( if c( ( Ts Ts A 2A om [ A (1 + ] 2 Ts m m c( ( if c( 1 ( Ts AT s / 2 if c( 1, ( Ts (31 (32 Accordig o (27, he DFT resul is refreshed every samplig period. Whe he slidig widow fucio g( coicides wih he dedicaed frequecy f, he resul reaches a maximum plaform. Seig a appropriae hreshold X h or adopig more a complex judgig algorihm, he daa ca be decoded. The process of demodulaio is show i Fig.1. ( i( g(- g(- g(- 1 T s X τ ( Xh Vsigal 1 Fig.1 Schemaic diagram of sigal demodulaio process. V. EXPERIMENT VERIFIATION A prooype sysem cosisig five odes is desiged o verify he proposed mehod. The block diagram of he ode is show i Fig.11, which is based o coveioal sychroic boos opology. The circui is corolled by a DSP wih relaed ierface. The ipu curre ad oupu volage are feedback for radiioal close-loop corol, ad he ripple o he bus is filered ad amplified for sigal decodig. V bus L 1 i Sesig urre Sesig Q 2 Filer Ad Amplifier Q 1 Oupu volage A/D Sample Driver PWM DSP TMS32F 2835 PWM Fig.11 Block diagram of a ode. 1 orol Ierface Load1 The prooype sysem srucure is he same as show i Fig.8 (a, where odes are coeced o he bus which is powered by a D volage source via a impedace sabilizaio ework. All he odes ca commuicae wih each oher. TABLE II. SPEIFIATIONS OF PARAMETERS Parameer of he Boos circui Value V bus (Ipu volage 115 V V ou (Oupu volage 24 V P ou (Maxim oupu power 1W L 1 (Boos iducor 56 μh i (Ipu capaciors 2.2 μf R s1 (ESR of i 3m f om (Swichig frequecy 1kHz f (Swichig frequecy 83.3kHz T sample (A/D sample period 2s AD resoluio 12-bi DFT period 6s Parameer of he Bus Value (Number of Nodes 5 Lie legh 2m L r (Impedace Machig Iducor 1μH r (Impedace Machig apacior 2.2μF R r (ESR of apacior r 3m The sysem parameers are lised i Table. II, where he swichig frequecies are seleced as f =1kHz ad

7 IEEE TRANSATIONS ON INDUSTRIAL ELETRONIS 7 f om =83.3kHz, ad he discree Fourier rasform period is 6s durig which f ad f 1 are orhogoal o oe aoher. I ca be calculaed ha m =6 ad m =5. The DSP A/D samplig period T sample is 2s, so 3 words memory space is eeded for DFT. The rasmissio rae is 2kbps, o realize reliable commuicaios exeded Harmoic ampliude (f =83.3kHz 1 5 f om=1khz f =83.3kHz (a Oe ode isalled o he bus exeded Harmoic ampliude (f =83.3kHz 4 2 f om=1khz f =83.3kHz ad f om=1khz (btwo odes isalled o he bus exeded Harmoic ampliude (f =83.3kHz 2 1 f om=1khz f =83.3kHz ad f om=1khz (c Five odes isalled o he bus. Fig.12 Waveforms of ripple ad he ampliude of he f harmoic. I he receiver, a bad-pass Op amp filer is desiged o amplify he daa sigal ad decrease he high harmoic compoes, whose high-pass cu-off frequecy is se abou 15kHz. The oupu sigal of he filer is abou 1V p-p ad sampled by 12-bi AD i he DSP TMS32F2835 every 2s. Accordig o (27, he f (83.3kHz compoe of he ripple is o-lie calculaed by he DSP. TMS32F2835 has a LA (orol Law Acceleraor core wih 32-bi floa-poi mah acceleraor by which DFT algorihm is implemeed i assembly laguage, ad he calculaio ime is less ha 1s. The ripple waveform of oe ode isalled o he bus is show i Fig.12(a, The ripple frequecy shifs bewee 1kHz ad 83.3kHz. I mos cases, he ode employs 1kHz swichig frequecy excep whe sedig bi. Fig.12(b shows he ripple waveform ad is DFT for wo odes operaig o he bus, ad Fig.12(c shows he case for five odes. If oe ode seds sigal, he ripple o he bus is comprised of he compoes of f ad f om. The f om (1kHz compoe o he bus is he syhesis of all odes wih differe phases, so he ampliude is variable. However, he f om harmoic compoe will o affec he DFT resul of f frequecy i he DFT coversio period. 1 1 V Se 2V/div V Received 2V/div 2μs/div Fig.13 Waveforms of se daa ad received daa. From Fig.12, as he umber of odes icreases, he ampliude of he f harmoic compoe reduces because he bus impedace decreases. If a cosa hreshold X Th is se o disiguish valid commuicaio sigal from oise, he codiio ha odes ca be suppored by his sysem is V XTh (33 where V is he DFT resul of he f compoe whe odes operae o he bus. The value of X Th is deermied by he bus oise which is relaed o he desig of sigal processig circuis ad power corol loop. Assume he capaciace of all he ipu capacior k (k=1,2, i he odes ad he machig capacior r are he same, i ca be cocluded ha he maximum umber of he sysem is 2V 1 Nmax 1 (34 XTh where V 1 is he DFT resul of he f compoe whe oe ode operaes o he bus. Fig.13 shows he waveforms of he se daa of a ode ad he received daa by aoher ode. The bi widh error bewee he seder ad he receiver is o more ha a DFT period (6s, so i is reliable for a serial commuicaio rae of 2kbps. To impleme a bus commuicaio sysem wih muliple odes, i is ecessary o exploi a Muliple Access orol (MA proocol for applicaio, which is beyod he scope of his paper.

8 IEEE TRANSATIONS ON INDUSTRIAL ELETRONIS 8 VI. ONLUSIONS This paper preses a mehod of power/sigal dual modulaio (PSDM o iegrae daa rasmissio wih power coversio. I he proposed PSDM sysem, he iformaio is embedded io he ripple of he coverer. By aalyzig he waveform of he ripple, commuicaio bewee odes ca be realized. Two basic mehods for PSDM are proposed, amely PWM/FSK ad PWM/PSK. The modulaio ad demodulaio process of PWM/FSK are discussed i deail ad a prooype sysem is used o verify he echique. Two priciples are cocluded: firsly, opology ad carrier may be cosrais o he PSDM sysem. The boos coverer circui is suiable for PSE while he buck circui is suiable for PD. A riagle wave is beer carrier opio sice a sawooh carrier iroduces a addiioal ierferece problem. Secodly, he carrier frequecies should be orhogoal wihi a calculaio period, ad he differece of he shifig frequecy is relaed o he commuicaio rae. The closer he shifig frequecies, he slower commuicaio rae. This mehod proposes a way of desigig a iellige power supply which ca sed messages from he corol core. The echique ca be applied i disribued power sysems or some special powerig arragemes. However, some problems should be cosidered before use. Firs, he ripple uilized o commuicaio should comply wih EMI sadards which resric he ampliude of he harmoic frequecies; secod, his mehod is o suiable for criical siuaios such as commuicaio-based corol sysems; hird, he effec of cross-ierferece bewee power corol ad sigal rasmissio was o aalyzed, ad may cause commuicaio daa error, bu his problem ca be overcome by addig a Auomaic Repea Reques (ARQ mechaism io he commuicaio proocol. REFERENES [1] A. Iera,. Floerkemeier, J. Misugi, ad G. Morabio, The Iere of higs [Gues Ediorial], IEEE Wirel. ommu., vol.17, o.6, pp.8 9, Dec. 21. [2] E. I. Gaura, J. Brusey, M. Alle, R. Wilkis, D. Goldsmih, ad R. Redic, Edge miig he Iere of higs, IEEE Ses. J., vol.13, o.1, pp , Oc.213. [3] D. Guiard, V. Trifa, S. Karouskos, P. Spiess, ad D. Savio, Ieracig wih he SOA-based Iere of higs: discovery, query, selecio, ad o-demad provisioig of web services, IEEE Tras. Services ompu., vol.3, o.3, pp , Jul.-Sep. 21. [4] Q. Wag, S. Gopalakrisha, Adapig a mai-sream Iere swich archiecure for mulihop real-ime idusrial eworks, IEEE Tras. Id. If., vol.6, o.3, pp , Aug.21. [5] A..Weaver, M.W. odry, Disribuig Iere services o he ework's edge, IEEE Tras. Id. Elecro., vol.5, o.3, pp , Jue 23. [6]. W. Thompso, Smar devices ad sof corollers, IEEE Iere ompuig, vol.9, o.1, pp.82 85, Ja.-Feb.25. [7] J. M. Guerrero, Liju Hag, ad J. Uceda, orol of disribued uierrupible power supply sysems, IEEE Tras. Id. Elecro.,vol.55, o.8, pp , Aug.28. [8] V.. Gugor, D. Sahi, T. Kocak, S. Ergu,. Buccella,. ecai, ad G. P. Hacke, A survey o smar grid poeial applicaios ad commuicaio requiremes, IEEE Tras. Id. If., vol.9, o.1,pp.28 42, Feb.213. [9] S. K. Mazumder, M. Tahir, ad K. Acharya, Maser slave curre-sharig corol of a parallel D D coverer sysem over a RF commuicaio ierface, IEEE Tras. Id. Elecro., vol.55, o.1, pp.59 66, Ja. 28. [1] E. J. Bueo, A. Herádez, F. J. Rodríguez,. Giró, R. Maeos, ad S. óbreces, A DSP ad FPGA-based idusrial corol wih high-speed commuicaio ierfaces for grid coverers applied o disribued power geeraio sysems, IEEE Tras. Id. Elecro., vol.56, o.3, pp , Mar.29. [11] T. Sauer, The hree geeraio of field-level eworks-evoluio ad compaibiliy issues, IEEE Tras. Id. Elecro., vol.57, o.11, pp , Nov. 21. [12] B. Groza, ad S. Murvay, Efficie proocols for secure broadcas i coroller area eworks, IEEE Tras. Id. If., vol.9, o.4, pp , Nov [13] A. Flammii, D. Marioli, E. Sisii ad A. Taroi, Desig ad implemeaio of wireless fieldbus for plasic machieries, IEEE Tras. Id. Elecro., vol.56, o.3, pp , Mar.29. [14] M., Sechilariu, B. Wag, F. Locme, Buildig iegraed phoovolaic sysem wih eergy sorage ad smar grid commuicaio, IEEE Tras. Id. Elecro.,vol. 6, o. 4,pp , Apr. 213 [15] Y. Ishii, Exploiig backboe rouig redudacy i idusrial wireless sysem, IEEE Tras. Id. Elecro., vol.56, o.1,pp , Oc.29. [16] E. M. Shakshuki, N. Kag, ad T. R. Shelami, EAAK-A secure isrucio-deecio sysem for MANETs, IEEE Tras. Id. Elecro.,vol.6, o.3,pp , Mar.213. [17]. Alcaraz ad J. Lopez, A securiy aalysis for wireless sesor mesh ework i highly criical sysem, IEEE Tras. Sys., Ma, yber.: Appl. Rev.,,vol.4, o.3,pp , Jul.21. [18] J.J. Fahie, Edward Davy, The Elecricia, pp , July, [19] T. A. Papadopoulos,. G. Kaloudas, A. I. hrysochos, ad G. K. Papagiais, Applicaio of arrowbad power-lie commuicaio i medium-volage smar disribuio grids, IEEE Tras. Power. Del.,vol.28, o.2,pp , Apr.213. [2] H. Meg, S. he, Y. L. Gua,. L. Law,P. L. So, E. Guawa, ad T. T. Lie, A rasmissio lie model for high-frequecy power lie commuicaio chael, i Proc. 5h I. of. Power Sys. Techol., Kumig, hia, Oc. 22, vol. 2, pp [21] M. A. Maah, N. Gio, ad. Baard, Effec of he power cable o daa rasmissio over a pulsewidh-modulaed ework, IEEE Tras. Id. Elecro.,vol.61, o.8,pp , Aug, 214. [22] N. Pavlidou, A. J. Ha Vick,J. Yazdai, ad B. Hoary, Power lie commuicaios: sae of he ar ad fuure reds, IEEE ommu. Mag., vol.41, o.4, pp34 4, Apr. 23. [23] V., K. Kilai, L. Koé, M. Liéard, ad P. Degauque, Feasibiliy of a high-bi-rae power-lie commuicaio bewee a iverer ad a moor, IEEE Tras. Id. Elecro.,vol.61, o.9, pp , Sep., 214. [24] T. Sauer ad M. Lobashov, Ed-o-Ed ommuicaio Archiecure for Smar Grids, IEEE Tras. Id. Elecro.,vol.58, o.4, pp , Apr [25] J. Liu, B. Zhao, J. Wag,Y. Zhu, ad J. Hu, Applicaio of power lie commuicaio i smar power osumpio, i Proc. IEEE ISPL, Mar. 21, pp [26] H. Kuboa, K. Suzuki, I. Kawakami,M. Sakugawa, ad H. Kodo, High frequecy bad dispersed-oe power lie commuicaio modem for eworked appliaces, IEEE Tras. osum. Elecro., vol.52, o.1, pp. 44 5, Feb. 26. [27]. Li, H. hu, S. Yeh,M. Lu, J. 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9 IEEE TRANSATIONS ON INDUSTRIAL ELETRONIS 9 Jiade Wu (M 11 was bor i Zhejiag, hia, i He received he B.Sc., M.S ad Ph.D. degree from he ollege of Elecrical Egieerig, Zhejiag Uiversiy, Hagzhou, hia, i 1994, 1997 ad 212, respecively. Sice 1997, he has bee a faculy member a Zhejiag Uiversiy, where he is currely a associae professor. From 213 o 214, he was a academic visior a he Uiversiy of Srahclyde, Glasgow, U.K. His research ieress iclude power elecroics corol, disribued power elecroics sysem ad fieldbus commuicaio. Ji Du (S 11 received he B.S. degree i elecrical egieerig from Zhejiag Uiversiy, Hagzhou, hia, i 211. urrely, he is workig oward he Ph.D. degree i he ollege of Elecrical Egieerig, Zhejiag Uiversiy, hia. His curre research ieress iclude power opimizaio of reewable geeraio ad commuicaio echique applied i power elecroics. Xiagig He (M 95 SM 96 F 1 received he B.Sc. ad M.Sc. degrees from he Najig Uiversiy of Aeroauics ad Asroauics, Najig, hia, i 1982 ad 1985, respecively, ad he Ph.D. degree from Zhejiag Uiversiy, Hagzhou, hia, i From 1985 o 1986, he was a Assisa Egieer wih he 68 Isiue of Aeroauical Idusrial Geeral ompay, Zhuzhou, hia. From 1989 o 1991, he was a Lecurer wih Zhejiag Uiversiy. I 1991, he received a Fellowship from he Royal Sociey of U.K. ad coduced research i he Deparme of ompuig ad Elecrical Egieerig, Herio-Wa Uiversiy, Ediburgh, U.K., as a Posdocoral Research Fellow for wo years. I 1994, he joied Zhejiag Uiversiy as a Associae Professor, where he has bee a Full Professor sice He is currely he Vice Dea of he ollege of Elecrical Egieerig, Zhejiag Uiversiy. His research ieress iclude power elecroics ad heir idusrial applicaios. Zhegyu Li (S 3 M 5 SM 1 received he B.Sc.ad M.Sc. degrees from he ollege of Elecrical Egieerig, Zhejiag Uiversiy, Hagzhou, hia, i 1998 ad 21, respecively, ad he Ph.D. degree from Herio-Wa Uiversiy, Ediburgh, U.K.,i 25. He is currely a Lecurer i Elecrical, Elecroic ad Power Egieerig wih Aso Uiversiy, Birmigham, U.K. He was a Research Associae wih he Uiversiy of Sheffield from 24 o 26, a R&D Egieer wih Emerso Idusrial Auomaio, orol Techiques PL from 26 o 211, a Seior Research Scieis wih Sharp Laboraories of Europe Ld. from 211 o 212, ad a Lecurer wih overy Uiversiy from 213 o 214. His research ieress iclude power elecroics ad is applicaios i reewable eergy, eergy sorage, moor drives ad power sysems. Yihua Hu (M 13 received he B.S. degree i elecrical moor drives i 23, ad he Ph.D. degree i power elecroics ad drives i 211, boh from hia Uiversiy of Miig ad Techology, Jiagsu, hia. Bewee 211 ad 213, he was wih he ollege of Elecrical Egieerig, Zhejiag Uiversiy as a Posdocoral Fellow. Bewee November 212 ad February 213, he was a academic visiig scholar wih he School of Elecrical ad Elecroic Egieerig, Newcasle Uiversiy, Newcasle upo Tye, UK. He is currely a research associae wih he Deparme of Elecroic & Elecrical Egieerig, Uiversiy of Srahclyde, Glasgow, UK. He has published more ha 2 echical papers i leadig jourals ad coferece proceedigs. His research ieress iclude PV geeraio sysem, D-D/D-A coverers, ad elecrical moor drives. hogwe Zhao (S 13 received he B.Sc. degree from he School of Elecroic Egieerig, Xidia Uiversiy, Xi a, hia, i 211, ad received he M.Sc. degree from he ollege of Elecrical Egieerig, Zhejiag Uiversiy, Hagzhou, hia, i 214. urrely, he is workig oward he Ph.D. degree i elecrical egieerig a he Uiversiy of Teessee, Koxville, TN, USA. His research ieress iclude wireless power ad commuicaio applicaios, D-D power coversios.