| 摘要 |
The present invention relates to an uninterruptible power supply. In order to minimize a DC component contained in an output voltage of a 3-level uninterruptible power supply, a control device of a rectifier comprises a rectifier voltage/current control part, a rectifier current offset command part, a rectifier PWM duty generating part, and a rectifier PWM converting part. Moreover, a control device of an inverter comprises an inverter voltage control part, an automatic inverter voltage offset control part, a manual inverter voltage offset command part, an inverter PWM duty generating part, and an inverter PWM converting part. The rectifier PWM duty generating part adjusts the balance of a rectifier input current by using a command value of the rectifier current offset command part to remove a voltage deviation of a DC link while the inverter PWM duty generating part adjusts the balance of an inverter output voltage by using an output value, generated from the automatic inverter voltage offset control part and the manual inverter voltage offset command part, to improve the stability of parallel driving, and minimizes a DC voltage flowing into a load side device, to protect the device. The rectifier PWM converting part generates a 3-level rectifier PWM signal, minimizing an unbalanced input current, by determining a duty sign outputted from the rectifier PWM duty generating part. The inverter PWM converting part generates a 3-level inverter PWM signal, minimizing an unbalanced output voltage, by determining a duty sign outputted from the inverter PWM duty generating part. |
