Representation of the Voltage Space Vector of the Multilevel Inverter in Oblique-Angled Coordinate Systems of Two Delta Voltages

The paper deals with two key oblique-angled coordinate systems for the space vector representation of the multilevel voltage source inverter which are considered as the coordinate systems of two delta voltages. Simplicity of the algorithm of the choice of the three nearest vectors to the reference and the determining of their actions durations under space vector PWM (SVPWM) realization in oblique-angled coordinates system is shown. The roles of the integer values and the fractional values of the relative delta voltages are revealed. The conclusion is drawn that the oblique-angled 60- and 120-degree coordinates are equivalent and similar from the point of view of steps, operations and results of the SVPWM algorithm application. The insertion of calculations in oblique-angled coordinates operations (with use of the presented formulas of corresponding transformations) as the subblock into the basic algorithm of calculations on orthogonal components has been proposed.