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

Dead time distortion is a well-known problem in pulse-width-modulated (PWM) voltage source inverter (VSI). Accurate detection of current polarity is a major issue for successful implementation of dead-time distortion compensation. Involving current sensor, for such purpose, increases the overall cost and complexity of the set-up. This may also lead to current measurement error due to current offset and scaling error, resulting in erroneous compensation. This article proposes a power function-based current sensor-less dead-time distortion compensation technique in single-phase PWM inverter. Here, the load voltage is sensed and utilized to compute a power function, which has been developed using instantaneous power theory (IPT) with significant modification to make it applicable to single-phase system. No topological modification or additional hardware in the power circuit is required for implementing such compensation. This reduces the overall cost and complexity of the set-up. The digital controller-based scheme is capable of automatically correcting the dead time distortion, even in case of on-line 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 concept has been done via simulations on a digital platform and through experiments on a laboratory prototype.