Multiple Open Switch Fast Fault Detection and Localization Algorithm for Tolerant CHB-MLI
Mayank Kumar
Abstract
Fast multiple open circuit fault (OCF) detection and faulty switch localization with a single switch fault-tolerant cascaded H-bridge multilevel inverter (CHB-MLI) under level-shifted pulse width modulation (LS-PWM) are presented in this paper. A simple redundant power cell (RPC) structure is used to make the multilevel inverter (MLI) fault-tolerant. The OCF with a healthy anti-parallel diode is considered for the proposed novel and fast switch fault detection, localization, and tolerant algorithm (FDLTA). The bridge with OCFs can be bypassed either through both upper or lower switches without the addition of any extra semiconductor device with CHB-MLI. Therefore, the exact switch fault localization within the H-bridge (HB) is compulsory. The diagonally opposite switch fault signatures within the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> power cell of CHB-MLI are approximately similar for (2 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> +1)-level CHB-MLI, where <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> is an odd positive integer, and therefore, the diagonally opposite switch fault detection and localization are very difficult. The analytical results for LS-PWM inverter output voltage under OCF conditions are derived using a double Fourier integral solution and Jacobi Anger expansion, and harmonic magnitude spectrum analysis for voltage and load current is presented under OCF conditions. Further, a laboratory-type fault-tolerant CHB-MLI is developed with RPC, and the proposed logic design is tested.