Study on the Strategy of Neutral Point Potential Control of Three-level Inverter

Taking the three-level inverter as the research object, the topology of the main circuit and the space vector voltage modulation algorithm in the 60° coordinate system are introduced. In order to reduce the harm caused by the midpoint potential imbalance, a closed-loop midpoint voltage and current detection method was proposed. By detecting the potential difference and current direction of the two capacitors on the DC side, balanced modulation was implemented in the software algorithm to achieve real-time suppression of potential imbalance. The principle of the balance control algorithm is easy to understand and it is difficult to achieve. It has been verified in simulation and experimental results.