ANALYSIS OF AN H6 INVERTER FOR TRANSFORMERLESS THREE-PHASE PV SYSTEMS
Abstract
Eliminating the leakage current is oneof the most important issues for transformerless three
phase photovoltaic (PV) systems. In this ipaper, ithe ileakage icurrent ielimination iof ia ithree-phase
ifour-leg iPV iinverter iis iinvestigated. iWith ithe icommon imode iloop imodel iestablished, ithe
igeneration imechanism iof ithe ileakage icurrent iis iclearly iidentified. iDifferent itypical icarrier-based
imodulation imethods iand itheir icorresponding icommon imode ivoltages iare idiscussed. iA inew
imodulation istrategy iwith iBoolean ilogic ifunction iis iproposed ito iachieve ithe iconstantcommon
imode ivoltagefor ithe ileakage icurrent ireduction.Finally ithe idifferentmodulation imethods
iareimplemented iand itestedonthe iTMS320F28335DSP i+XC3S400FPGAdigital icontrol iplatform.
iThe iexperimental iresults.The itransformer iless iinverter itopologies iSolar icells iproduce idirect
icurrent ielectricity ifrom isun ilight iwhich ican ibe iused ito ipower iequipment ior ito irecharge ia
ibattery. iThe ifirst ipractical iapplication iof iphotovoltaic iwas ito ipower iorbiting isatellites iand iother
ispacecraft, ibut itodaythe imajority iof iphotovoltaic imodules iare iused ifor igrid iconnected ipower
igeneration. iIn ithis icase ian iinverter iis irequired ito iconvert ithe iDC ito iAC. iThere iis ia ismaller
imarket ifor ioff-grid ipower ifor iremote ihave isuperior iefficiency ithanks ito isaving itransformer ibut
ithere isemiconductor idevices istill ihardswitching istated ipresent i.A ifamily iof iZCT itransformer iless
iinverterwithsinusoidal iPWM imodulation iis ideduced iby iusing ifuzzy ilogic icontroller
