A PWM Pulse Pattren Optimization Method Using Carrier Frequency Modulation

This paper describes a PWM pulse pattern optimization method using the carrier frequency modulation (CFM) technique. This new technique is aiming at not only reducing the magnetic acoustic noises of the driven motors but also improving the performance of sinusoidal inverters.The PWM pulse patterns are basically controlled so that the time-integral function of voltage vectors in the space vector notation may draw a circular locus. In addition to this, the carrier frequency, practically the sampling frequency for inverter control, of PWM is also regulated so that a performance index (PI), which represents the degrees of achieving objectives, may be minimized. Here two PIs, one is for minimizing the distortion of output currents and the other is for minimizing the torque ripples of driven motors, are discussed respecively.Finally, CFM is implemented using a single-chip microprocessor, and the experimental results demonstrate the validity of the proposed mehtod.