Investigation and Improvement of Phase-Shift Self-Oscillating Current Controller for power electronic converters at high switching frequency

This paper deals with effects of additional phase-shifts and time delays in a system controlled by a Phase-Shift Self-Oscillating Current Controller (PSSOCC). This analog controller is used for current controls of DC/AC and AC/DC power converters. It is able to accurately track current references and is able to produce PWM signals where it defines the maximum switching frequency. Its robustness has been proved in former works. It is involved in a large range of applications such as motor controls and power factor corrections. However, it is the first time that additional phase-shifts and time delays are taken into account because until today, this controller was employed for regulation of converters where switching frequencies were around 10-20kHz. Thus, current sensor bandwidths and time delays were neglected. Nevertheless, for applications working at higher frequencies, these elements can have a serious impact on maximum switching frequencies. Here, models are proposed in order to find analytical expressions defining the maximum switching frequencies taking into account additional phase-shifts of current sensors and time delays due to logic devices. On a theoretical point of view, these delays could relate to logic or analog stages too.