Three‐phase three‐level one‐cycle controlled bidirectional ac–dc neutral‐point‐clamped converter without having voltage sensors

A three‐phase three‐level bidirectional ac–dc neutral‐point‐clamped converter (3 L‐NPC) based on one‐cycle control (OCC) is proposed in this study. It ensures that the 3 L‐NPC converter operates stably during inverting mode of operation. A neutral point potential regulator is also presented which adds a dc offset to the three‐phase modulating signals to nullify the deviation in the neutral point potential. First, a one‐cycle controlled (OCC) 3 L‐NPC converter which requires the sensing of instantaneous phase voltages of the utility is presented. Subsequently, a modified version of the OCC‐based 3 L‐NPC converter which does not requires sensing of the instantaneous phase voltages is proposed. The modified OCC‐based 3 L‐NPC estimates instantaneous phase voltages of the source from the pulse width modulation (PWM) switching sequence of the converter. The viability of the schemes is confirmed through a detailed simulation and experimental studies.