Design and Implementation of Single-Phase Three-Wire Inverter for Power Conditioning System

• Main Authors: Lo, Shun-Hung, 羅順弘
• Other Authors: Wu, Tsai-Fu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/93485092582131506850

碩士 === 國立清華大學 === 電機工程學系 === 102 === Considering the power distribution system, this research develops a single-phase three-wire bidirectional inverter for integrating renewable and battery back-up energy into uninterruptible power system (UPS). The inverter can control the power flow between the DC bus and utility power. Additionally, it can also work as a UPS. The inverter consists of a power stage and a control stage. The power stage is realized with a dual half-bridge configuration, and a single-chip microcontroller Renesas RX62T is adopted to realize the control stage. The major contributions of this research can be summarized as follows. First, a multifunctional single-phase three-wire inverter is proposed. The operation of the inverter includes grid-connection and voltage-regulation modes. When utility power operates normally, the inverter operates in grid-connection mode. There are two functions in grid-connection mode, power-injection and rectification. With power-injection function, the inverter will inject real power to utility power. With rectification function, the inverter will buy power to replenish the DC bus. When utility power fails, the inverter can transit seamlessly from grid-connection mode to voltage-regulation mode and function as a UPS. Secondly, the control law includes inductance and grid voltage with division-summation (D-Σ) digital control. Hence, the inverter is allowed to have a wide inductance variation, reducing core loss and size significantly. Thirdly, with load impedance estimation and repetitive control, the D-Σ control can be applied to voltage-regulation mode and the inverter with the D-Σ control can shape sinusoidal output voltage with low harmonic components under various types of load conditions. Finally, the inverter has been implemented and tested. Simulated and experimental results have verified the proposed control scheme and feasibility of the inverter.