Current Sensor-Less Dead Time Distortion Compensation in Three-Phase PWM Inverter

Dead-time distortion is a typical problem in pulse width modulation (PWM) voltage source inverter (VSI). Accuracy in current polarity detection is a major issue in implementing dead-time distortion compensation successfully. This article proposes a power function-based current sensor-less dead-time distortion compensation technique in three-phase PWM VSI. The power function, when developed by applying instantaneous power theory (IPT) directly, may not be able to detect the current polarity accurately. This has been investigated in detail in this article. In the proposed technique, this problem is overcome by sensing and utilizing the pole voltage of the inverter and developing the power function for each phase using IPT with significant modification to make it applicable to each phase individually. There is no requirement of topological modification or additional hardware in the power circuit for implementing such compensation. This reduces the overall cost and complexity of the set-up. The scheme is capable of automatically correcting the dead-time distortion, even in case of online load change. The attractive feature of this scheme is its simple principle, allowing it to be implemented in low-cost digital controllers. Validation of the proposed compensation technique is executed in digital simulation and through experiments in laboratory.