| 摘要 |
PROBLEM TO BE SOLVED: To provide intelligent level transition systems and methods for a transformerless uninterruptible power supply.SOLUTION: Systems and methods are provided for controlling an uninterruptible power supply (UPS) to transit between three- or higher-level operation and two-level operation in a neutral-point-clamped (NPC) inverter. In an example, a UPS system includes an NPC inverter and a controller. The NPC inverter may supply power to a load. The controller may control the inverter to operate in a three- or higher-level mode when the load is substantially balanced and to operate in a two-level mode when the load is substantially unbalanced. |
