A hybrid control scheme of cascaded H-bridge inverters for grid-connection photovoltaic systems

作者：Wang, Fusheng; Zhang, Dehui^*; Dai, Zhiqiang; Yang, Le

来源：Transactions of China Electrotechnical Society, 2016, 31: 137-145.

• Cascaded H bridge (CHB)
• Cascaded H-bridge
• Cascaded H-bridge inverters
• Dummy unit
• Hybrid modulation
• Maximum power point tracking controls
• Sorting algorithm
• Total Harmonic Distortion (THD)

The single-phase cascaded H-bridge (CHB) inverters for grid-connection photovoltaic (PV) systems have been explored with the features of modular, low harmonics and so on. The power harvested from PV modules are different exceedly because of serious environment, or even one or more modules'power are equal zero that becoming dummy units which affect system's stability and redundancy. This paper proposes an improved hybrid modulation which is a mix of "staircase pulse width modulation (PWM) sorting algorithm". This method adopts low frequency staircase modulation to expand stable operating region fundamentally, and uses high frequency PWM modulation to shape the current and decrease its total harmonic distortion (THD). Moreover, sorting the errors of dc voltages to get maximum power point tracking (MPPT) control, then analyze this method's stable operating condition from active power point. The proposed hybrid modulation have simple control structure, and can control the dummy unit effectively with individual MPPT. Finally, the simulation and experiment results validate the effectiveness and feasibility of the developed ideal.

• 出版日期2016
• 单位合肥工业大学