Small-Signal Circuit Model of Zeta DC-DC PWM Power Converter Including Parasitic Components and Its Application

This paper presents a new rigorous derivation of equations for the apparent power components for periodic nonsinusoidal voltage and nonsinusoidal current waveforms in single-phase power circuits with passive loads under steady-state conditions. It is shown that Budeanu's definition of the multiharmonic reactive power is incorrect, resulting in an incorrect definition of the distortion power and the nonactive power. The derivations are carried out in the frequency domain using Fourier analysis of voltage and current waveforms. The IEEE Standard describes the power factor in terms of total harmonic distortions (THDs), whereas this paper describes the power factor in terms of the components of the apparent power, representing another advance in electric power theory. A simulation of a circuit with a square-wave voltage source is given. The results can be useful for evaluating the power quality of various power circuits that contain nonsinusoidal excitations, nonlinear loads, or switching components, such as RF power amplifiers, switch-mode power supplies, LEDs, and variable speed motor drives with multiharmonic voltage and current waveforms.