Analysis of the current-fed push-pull parallel resonant inverter implemented with unidirectional switches

Abstract — A modified Current-Fed Push-Pull Parallel Resonant Inverter (CFPPRI), that includes diodes in series with the switches, was analyzed and tested by simulation and experimentally. The modified power source is capable of producing a low THD output voltage within a relatively wide frequency range. A comparison between the modified topology and the basic CFPPRI, in terms of output signal quality and efficiency was carried out. It was found that the modified inverter is more efficient and that it produces an output signal that is less distorted as the running frequency deviates from resonance. Operation with a capacitive load in an offresonance mode was demonstrated by driving a rotary piezoelectric motor by the modified inverter. I

Time domain design of digital compensators for PWM DC-DC converters

Abstract- A time-domain design method for digital controller of PWM DC-DC converters that was developed, tested by simulations and verified experimentally. The proposed approach is based on the fact that the closed-loop response of a digitally controlled system is largely determined by the first few samples of the compensator. This concept is used to fit a digital PID template to the desired response. The proposed controller design method is carried out in the time domain and thus, bypasses errors related to continuous to discrete domain transformation and discretization. Digital PID controllers for a Buck and Boost type converters were implemented experimentally on a TMS320LF2407 DSP core. The measured closed-loop attributes were 3.5KHz bandwidth and phase margin of 40 o for the Buck converter, and 1.6 KHz and 40 o for the Boost. Good agreement was found between the design goals and the experimentally determined response. I

Time Domain Identification of PWM Converters for Digital Controllers Design

Abstract-A discrete time-domain based system identification method for PWM DC-DC converters is presented. The proposed procedure is capable of successfully reconstructing the system’s model from an arbitrary excitation at the command input. In this study, a step perturbation was applied, which is simple to apply and has an intuitive interpretation of the output response. The effects of switching and quantization noise were overcome by choosing the sampling instance to be after the switching oscillations decay significantly and by averaging the responses of synchronously perturbed sequences. The proposed method was evaluated on Buck and Boost converters. The digital data acquisition procedure was implemented on a TMS320F2407 DSP core. Excellent agreement was found between simulations and experimental results. I