1、Pulse Width Modulation(PWM)(Chopping control)DC/DCAC/ACDC/ACAC/DCControlsignalCarrier图6-4MudulationCarrierUd+V1V2V3V4VD1VD2VD3VD4uoRLurucControlsignalCarrier图6-4MudulationCarrierUd+V1V2V3V4VD1VD2VD3VD4uoRLuruc 1002+-1234+-02+-4+-01+-3+-5+-Magnitude(%)(nc+kr)0.20.40.60.81.01.21.4kna=1.0a=0.8a=0.5a=01
2、002+-1234+-02+-4+-01+-3+-5+-Magnitude(%)0.20.40.60.81.01.2kna=1.0a=0.8a=0.5a=0(nc+kr)图6-18ucur1uOturur1uOtur3图6-19ucurU1urV1urW1uuUNUd-UdOtOurUurVurWucOtOOOOtttttuVNuWNuUVu1-11-1-0.5uP2Ud2Udacbabbccaabbcca1 1 1T Phase variables(a,b and c)produceline-to-line variables(ab,bc and ca)in plane-Line-to-li
3、ne variables(ab,bc and ca)do not have-component in-coordinate systemVector Space of 3-phase Line-to-Line VariableswherecabcababcvvvTvv/232302121132/abcTabbccavv Space vectorjev22vvvv1tanIf Vm is the amplitude of balanced,symmetrical,three-phase line-to-linevoltages,then mV23vidcvabVdcsascsb010000000
4、000011111111111icibib+ic0iaia+icia+ibia+ib+icSwitching statepnnppnnpnnppnnppnppppnnnvcavbcVdcVdcVdcVdcVdc-Vdc-Vdc-Vdc-Vdc-Vdc-Vdc000000000000iaibicvavcvbsasbscpnVdcidc/11312222033310222abdcdcpnnabcbcpnncadcdcpnnvVVvVTvvvVVj1pnneVVdcV230vv1tanab,bccavv1VdcdcdcppncabcababcppnppnVVVvvvTvvV2002323021211
5、32/j2ppneVVdcV290vv1tanab,bccav2V00000232302121132/pppcabcababcppppppvvvTvvV0VV0pppab,bcca0VdcV23015090-90-1500-3000()pnnV1ppnV2npnV3nppV4nnpV5pnpV6pppV0nnnV0Sector IIVIIIIIVVIat center pointab,bccapnnV1ppnV2npnV3nppV4nnpV5pnpV6nnnpppV0ab,bccavvjrefrefevvVm22V23vvtvv1tanwhereIn general,120tV120tVtVv
6、vvmmmrefcabcabcoscoscosAssume)()()(tjmrefetV23tVpnnV1pnpV6ppnV2npnV3nppV4nnpV5at center pointnnnpppV0refVSiiiT0iT0refTTdtVdtViS,Vref()V1()V2()T1T2T0TStTotal area of=Area of211S211STTTTTT02T01T0refdtVdtVdtVdtVFor examplevab,bccavvpnnV1pnpV6ppnV2npnV3nppV4nnpV5nnnpppV0refV iaibicvavcvbsasbscpnVdcidcab
7、c101010IIVIIIIIVVI2V0V1V11Vd22VdrefV211S211STTTTTT02T01T0refdtVdtVdtVdtV2211SrefTVTVTV2211ST6060VT01VTsincossincos)sin(60V32dTT11S1sin22S2V32dTT210dd1dFrom HF synthesis definition,Assume is constant in TS,where30refV2V0V1V11Vd22VdrefV图6-26Filter+-uu*u2Ud2Ud图6-31PI+-LoadTriangular-wavesin(t+2k/3)(k=0,1,2)cos(t+2k/3)(k=0,1,2)u*dud+-+-+iduRuLXLRuA,B,CudRLua,ub,uc
