Steady-State Operation
An electrical machine operates at steady-state when it is fed with a voltage of constant magnitude and frequency. In the special case of a three-phase machine fed by a pulsewidth-modulated power inverter, steady-state operation is assumed when the inverter is commanded by a voltage reference vector of constant magnitude and frequency.
The switched voltages of the inverter generate a three-phase sinusoidal stator voltage distribution inside the electrical machine; this voltage distribution is described by the respective stator voltage space vector. At steady-state operation, the time-average amplitude and the time-average frequency of the fundamental waveform of the stator voltage are equal to the respective quantities of the reference voltage.
However, the instantaneous value of the stator voltage may differ from the reference voltage because of switching harmonics, non-idealities of the commanding power inverter, phase delay, and non-idealities and presence of passive components elements in the electrical connection path between inverter and machine.