Maximum-Current Generalized DPWM for Enhanced Thermal Capability and Support of Grid-Tied Converters During Asymmetrical Faults

Power electronics converters are a key component of modern power grids, enabling efficient energy conversion and control of renewable energy sources. The grid codes impose that power converters, deployed in renewable energy-based generation systems, must be capable of performing low-voltage ride-through (LVRT) to enhance grid stability during severe events like faults. Additionally, the converter must supply enough current to trip the circuit breaker, ensuring effective grid protection. However, the overcurrent capability of power electronic converters is constrained by their thermal limits, primarly defined by the maximum allowable device junction temperature (Tj,max). The power converters thermal capability improvement can be obtained by thermally compensated modulation techniques like Discontinuous PWM (DPWM). However, understanding the thermal behavior of power devices during asymmetrical grid faults is crucial, as these faults are not only among the most common grid disturbances but also generate unbalanced currents that challenge the effectiveness of standard DPWM schemes. This paper investigates the application of a Maximum Current-based Generalized DPWM (MC-GDPWM) technique during asymmetrical grid faults, focusing on its potential to enhance the thermal performance of overloaded converters.