PWM power converter voltage quality bounds and their applicability to non-PWM control schemes

The paper presents simple closed-form analytical expressions for PWM power converter ripple voltage Normalized Mean Square lower and upper bounds. These estimates obtained in time domain are asymptotic in the sense that switching-to-fundamental frequencies ratio is supposed infinitely large. Ripple voltage Normalized Mean Square in the first approximation represents normalized additional eddy current iron core loss in electric motor, transformer, or coupling inductor caused by converter switching that is a dominant switching loss mechanism. Non-PWM voltage control schemes like sliding mode, hysteresis, direct torque and power control, and predictive control may deliver better tracking, and disturbance rejection performance at the expense of compromising voltage quality thus increasing converter switching caused iron core loss. Comparison with PWM voltage quality asymptotic lower and upper bounds may be useful for making a fair assessment of different non-PWM strategies from additional switching caused iron core loss perspective.