Matching Resonant Switches Operation Using Classical Pulse-Width Modulation Algorithms

Abstract

This paper presents a new method of controlling resonant switches of a converter, in which the instants of control pulses supply to the main and auxiliary switches of the circuit are strictly synchronized with pulse-width modulation (PWM) logic signals. Any classical options providing the specified quality of the output voltage and current can be used as such signals. The control pulses durations of the main switches have the same time intervals as those of the PWM control signals, since the control pulses are shifted relative to the PWM signals by a constant time delay. The durations of control pulses of auxiliary switches used to activate resonant switching processes are constant and independent of changes of the electric mode parameters of the circuit and the scatter of the parameters of resonant circuit components. The synchronizing mode is shown to be achieved by introducing two additional time intervals into each resonant switching cycle compensating the effect of external and internal factors on the duration of the required control pulses for the main and auxiliary switches of the converter. Such additional time intervals are the duration of free—that is, without significant loss of power—circulation of current (energy) in the inductance of the resonant circuit. In addition, it is shown that the necessary conditions for free circulation are the capability of the main converter switches for bilateral current conductivity and the absence of energy absorption sources in the circulation circuit. The diagrams are presented of switching processes demonstrating the advantages of a new method for controlling resonant switches of the inverter in a wide range of the supply voltage and load current variations of the circuit.