A novel estimation procedure for the aperture time in asynchronous sinusoidal PWM systems

A novel analytical technique is presented for the determination of the modulated pulse duration in sinusoidal asynchronous pulse width modulated (PWM) systems. A reasonable level of modulated aperture accuracy can be obtained with little computational effort using the proposed method. The method of evaluation of the pulse edge transitions is based on a second order Taylor series expansion of the sinusoidal reference signal about the zero crossing points of the triangular carrier used as the switching waveform in the comparator modulator. The accuracy of the estimated pulse edge transition times can be gauged from a comparison with values obtained using simulated PWM comparator operation, as a measurement reference, with a very small step size. The simplicity of the proposed solution makes it an attractive feature in an online DSP implementation of PWM operation for adaptive motor control