1、Power ElectronicsChapter 4 DC to AC Converters(Inverters)LoadS1S2S3S4iouoUdtuoiot1t2Device commutationForced commutationLine commutationLoad commutationFor fully-controlled devicesFor thyristorsVoltage Source Inverter (VSI)Current Source Inverter (CSI)+-CRLUdV1V2V3V4VD1VD2VD3VD4uoio-RLUdiouoV1V2VD1V
2、D2Ud2Ud2uoUmiot1t2t3t4t5t6V1V2V1V2VD1VD2VD1VD2UG1UG2+-CRLUdV1V2V3V4VD1VD2VD3VD4uoiouoUmiot1t2t3t4t5t6V1V2V1V2VD1VD2VD1VD2UG1,4UG2,3VD4VD3VD4VD34343VVVVtttUu5sin513sin31sin4doddo1m27.14UUUdd1o9.022UUU tOtOtOtOtOuG1uG2uG3uG4uoiot1t2t3iouo+-CRLUdV1V2V3V4VD1VD2VD3VD4uoioLoad+-iouoUdV1V2VD1VD2For line vo
3、ltageFor phase voltage of the load0WNVNUNUUUnktnntUtttttUusin)1(1sin3213sin13111sin1117sin715sin51sin32ddUVddUV1m1.132UUUddUV1mUV178.062UUUU DC side is constant current,high impedance (current source,or large inductor)AC side current is quasi-square wave.AC side voltage is determined by the load.No anti-parallel diodes are needed.sometimes series diodes are needed to block reverse voltage for other power semiconductor devices.ACRLLdIdVT1VT2VT3VT4LT1LT2LT3LT4uoio
