Two level three phase voltage source inverter fed low power AC induction motor based on unipolar pulse width modulation method
Space vector modulation is a well established theory. Generally, a three phase voltage source inverter generates eight switching states, including six active and two zero states, by the bipolar method. This study proposes a novel way to synthesise the output voltage vector by turning off both switches in a leg. Accordingly, new leg switching states are defined. A unipolar method is used to achieve discontinuous pulse width modulation. The complex reference vector is located by one active vector and two newly defined leg switching states. The most notable features of the proposed method are that it completely overcomes the problem of dead time without current polarity detection. These features make it very attractive for low cost, low power constant volts per hertz (V/f) open loop, three phase AC induction motor applications.