  A new carrier-based pulse-width modulation (PWM) technique to control power
inverters is presented in this paper. To generate the output waveform, this
technique compares a harmonic-injection modulating wave and a
frequency-modulated triangular carrier wave. The instantaneous frequency for
the carrier wave is adjusted according to a periodic function synchronized with
the fundamental term of the modulating wave. The main motivation for using this
technique compared to a classic PWM sinusoidal technique revolves around the
reduction of total harmonic distortion, the reduction of the distortion factor
and the shift of temporal harmonics to higher frequencies for any modulation
frequency order. Experimental results show that it is possible to optimize the
time harmonics generated to minimize vibrations produced by an induction motor
when it is fed with a DC/AC converter controlled by the proposed control
strategy. This is made possible by using a control parameter that modifies the
instantaneous frequency of the carrier wave without modifying the number of
pulses per period of the modulating wave, i. e. the mean value of the carrier
wave frequency. The proposed technique is applied to an open loop-controlled
inverter that operates an induction motor, helping to reduce the vibration
levels produced.
