Wpływ pojemności pasożytniczych transoptora na sterowanie tranzystorami w przekształtniku impulsowym

Abstract

Optocouplers are widely used, e.g. in the switching converters, in which they are used to obtain electrical isolation between gate transistors circuits and microprocessor controller. In transoptors exists parasitic capacitances which couples output and input circuits of the system. The influence of these capacitances is negligible for most applications. However, in switching converters, where the potentials of the input and output circuit of an optocoupler changes very fast, the presence of parasitic capacitances can lead to the distortion of transistors control signals. The paper discusses the general structure, key features and parameters of digital optocouplers. Cause and location of parasitic capacitances was shown in a simulation model of optocoupler, which takes into account the parasitic capacitances was designed. Simulation results illustrating the impact of capacitance and rate of voltage change to waveform of the transistors control signals were presented. Shows selected results of laboratory verification