Today’s Patent – Modulation strategy suitable for balancing losses of power switches in bridge arm of neutral point clamped three level inverter and implementation method

The said invention (US12088215B2) was invented by Huafeng XIAOXiaobiao Wang, patented by USPTO on 17-02-2022. Currently, it stands assigned to Southeast University.

The rapid expansion of renewable energy, particularly offshore wind and photovoltaic power generation, has increased the demand for high-voltage, high-power inverters. Three-level inverters, such as the Neutral Point Clamped (NPC) inverter and its variations, offer advantages like lower harmonic content and improved efficiency. However, conventional NPC inverters suffer from unbalanced power losses between the inner and outer power switches, leading to higher thermal stress and reduced inverter lifespan. Previous strategies like Adjustable Loss Distribution (ALD) and Only One Zero (OOZ) modulation attempted to address this issue but either faced operational limitations or failed to balance losses effectively.

The proposed modulation strategy improves loss distribution in NPC three-level inverters by dynamically selecting modulation styles based on the power factor angle. It enables a balanced distribution of switching and conduction losses across all power switches, reducing thermal stress and enhancing inverter lifespan. Unlike previous methods, this strategy applies to the full power factor range, ensuring stable operation and digital implementation feasibility. This advancement is crucial for offshore wind power, photovoltaic systems, and energy storage applications, significantly improving efficiency and reliability.