KOLEJ KEMAHIRAN TINGGI MARA PASIR MASLUBOK JONG, 17000 PASIR MAS

INVERTERBY : MUHAMMAD AFIQ BIN ABDUL GAFAR MOHAMAD TAUFIQ BIN BAHAROM NOOR AZREEN BT MOHD NAPIS

3 PHASE INVERTER Used for (VFD) application and for HVDC power

transmission. three single-phase inverter switches each connected to one of the three load terminals. the operation of the three switches is coordinated so that one switch operates at each 60 degree point of the fundamental output waveform

This creates a line-to-line output waveform that

has six steps. The six-step waveform has a zero-voltage step between the positive and negative sections of the square-wave such that the harmonics that are multiples of three are eliminated

BASIC CIRCUIT 3 PHASE DIAGRAM

3 PHASE BRIDGE INVERTER Multilevel inverter Voltage source inverter PMW inverter

Multilevel Inverter A solution to increase the converter operating

voltage above or to increase the quality of output voltage waveform without adding any complexity to other circuit.

Voltage Source Inverter Used to extensively in motor drives, active filter

and unified power flow controller in power system and uninterrupted power supplies to generate controllable and AC voltage magnitude using various pulse-width modulation ( PWM).

PMW Used for high power application. Example three single-phase half (or full)-bridge

inverter can be connected in parallel.

180 Degree Conduction Each

transistor conduct 180 degree.Three transistors remain at any instant time. When MOSFET S1 on, terminal a is connected to positive terminal of the dc input voltage. When MOSFET S4 on, terminal a brought negative terminal on the dc source. There are six mode operation in a cycle and duration 60 degree.

Switch state for three phase VSI based on 180 degree

120 Degree Conduction For this type control signal, each MOSFET

conduct for 120 degree. Only two MOSFET remains on at any instant times. There are delay of / 6 between S1 and S4 . Thus there should be no short circuit of the dc supply through one upper and one lower MOSFET.

Conclusion At any time, two terminal loads are connected to

the dc supply and the third one remain open. The potential of this open terminal depends on the load characteristic and would be unpredictable. Then because one MOSFET conduct for 120 degree, the MOSFET are less utilized as compared with those 180 degree conduction on the same load condition.Thus, the 180 degree conduction is preffered and it is generally used in three-phase inverters.

The End.