  An implementation of a harmonic injection pulse width modulation
frequency-modulated triangular carrier (HIPWM-FMTC) control strategy applied to
a multilevel power inverter feeding an asynchronous motor is presented. The aim
was to justify the reduction in acoustic noise emitted by the machine compared
with other strategies in the technical literature. In addition, we checked how
the THD at the inverter output was reduced compared to the other control
techniques used as a reference. The proposed strategy is based on frequency
modulation of the triangular carrier. The main advantage of the proposed method
is that only one control parameter is required for modifying the electrical
spectrum. Therefore, the mechanical natural frequencies and spatial harmonics
of the machine can be avoided, and acoustic noise can be reduced. The
effectiveness of the technique was demonstrated after laboratory validation by
comparing the acoustic results for a 1 kW motor. The results obtained from the
laboratory tests are presented and compared with those of other acoustic
measurements using different PWM strategies.
