A DC voltage converter with a series resonant inverter and asymmetric control of power transistors

Resumo

The interest in dc converters with a series resonant inverter (resonant converters) is due to the fact that they easily realize switching of semiconductor devices at zero current and zero voltage in a device. This makes it possible to significantly reduce power losses during switching of semiconductor devices and to realize the operation of a dc–dc converter at higher frequencies with a high efficiency. In the foreign literature, many circuits of resonant converters are described and many results of experimental studies are presented. However, the theory of such converters has not been sufficiently developed and theoretical studies are conducted using approximate methods, for example, fundamental-harmonic method. This paper describes the operating principle of the power part of a dc–dc converter with a series resonant inverter with asymmetric control in the discontinuous conduction mode (DCM), when the switching frequency is less than the resonance frequency of the LC circuit. The features of symmetric and asymmetric control of the inverter’s power transistors are described, in which bipolar current pulses are formed in half of the switching period. An algorithm for asymmetric control of transistors is proposed, and a scheme for implementing this algorithm on discrete components in the form of a virtual model in the Matlab–Simulink environment is presented. The results of modeling (transient and steady-state conditions, external characteristics, and other dependences), as well as the results of a comparison of the taken and theoretical (constructed from analytical relationships) characteristics, are presented.