วงจรแปลงผันกำลังไฟฟ้าที่มีความเพี้ยนของกระแสด้านเข้าต่ำสำหรับแหล่งจ่ายไฟต่อเนื่อง / สกุลรัตน์ ศิริพันธ์โนน = A power converter with low input current distortion for UPS / Skulrath Siriphannon
This thesis presents a new single-phase power converter for uninterruptible power supplies which has a low input distortion and high power factor. The new structure of the power converter results from the integration of a switched-mode rectifier with a full-bridge inverter by sharing one common arm. The new converter's topology enables both the switched-mode rectifier and the inverter to be realized by using only 4 switching devices. The main features of the proposed converter are that it uses a simple switching technique to reduce the harmonics in the supply, and that the duty circle of the common arm is sinusoidally modulated to reduce the required dc bus voltage. Moreover, this thesis also proposes a new control method for the PWM inverter of uninterruptible power supplies. The proposed control technique consists of a state-feedback controller to obtain a fast transient response and a repetitive controller to eliminate the steady-state periodic error. The experiment results confirm the good characteristic of the proposed converter with the supply current becoming sinusoidal and the output voltage having a low THD even in the case of non-linear loads.
