  An optimal time-domain pulse width modulation technique is presented for
single-phase and three-phase inverters under the constraint of sinusoidally
modulated voltage pulse widths. Harmonic content in currents and voltages is
expressed as function of displacement factors, which characterize the placement
of the sinusoidally modulated voltage pulses in each sampling subinterval.
Implications of symmetries on these displacement factors for three-phase
inverters are discussed. Minimization of harmonics is stated as an optimization
problem, which is then numerically solved to reveal improvements in harmonic
performance.
