Current controller reduced switching frequency for VS-PWM inverter used with AC motor drive applications

The current control system of the three-phase voltage source inverter used in AC motor drive application is presented in the paper. This system, operating in the rotating reference frame fixed to the motor flux, minimizes the switching frequency inverter transistors. The optimal inverter output voltage vector positions, recorded in an electrically programmable read-only memory, ensure the longest path of moving the stator current vector inside the tolerance band which is square shaped. Theoretical bases for the choice of optimal inverter output voltage vector positions are discussed.