Experimental Implementation of a 3-Level TNPC-IGBT Inverter for Uniform Stress Distribution and THD Mitigation: MPC-Driven Switching Optimization, LCL Filter Integration, and Real-Time Stress Monitoring

The increasing demand for high-quality power conversion in industrial applications has led to advancements in multilevel inverter design and control. This paper presents a design and experimental implementation of a 3-level T-type neutral-point clamped (TNPC) inverter utilizing space vector pulse width modulation (SVPWM) and model predictive control (MPC) for optimized switching state selection. The proposed approach ensures DC-link voltage balance, symmetrical load voltage and current, reduced voltage harmonics, and uniform stress distribution among the inverter’s three legs. An LCL filter is integrated based on phase margin optimization criteria to maintain total harmonic distortion (THD) of the current within acceptable limits. Real-time stress monitoring circuits are developed to assess key parameters including on-state voltage, case temperature, and collector current, which are essential for the reliability analysis of the IGBT modules. The configuration is validated through laboratory experimentation and the use of a highly inductive load with currents of up to 100 A. Findings indicate uniform voltage and current distribution, reduced harmonics of less than 0.1% for current and 5% for voltage, under full load conditions, and enhanced dynamic performance and system reliability, making the proposed method suitable for high-quality industrial applications. Furthermore, the developed experimental setup with uniform stress distribution simplifies the TNPC-IGBT module reliability assessment using a one-leg equivalent circuit to estimate the lifespan and conduct reliability analysis, rather than analyzing the module’s three legs.