Implementation of a High Efficiency Grid-Tied Multi-Level Photovoltaic Power Conditioning System Using Phase Shifted H-Bridge Modules

Implementation of a High Efficiency Grid-Tied
Multi-Level Photovoltaic Power Conditioning
System Using Phase Shifted H-Bridge Modules
Jong-Pil Lee†, Byung-Duk Min**, and Dong-Wook Yoo*
†*Power Conversion Research Center, Korea Electrotechnology Research Institute, Changwon, Korea
**Green Power Co. Ltd, Suwon, Korea
Abstract
This paper proposes a high efficiency three-phase cascaded phase shifted H-bridge multi-level inverter without DC/DC
converters for grid-tied multi string photovoltaic (PV) applications. The cascaded H-bridge topology is suitable for PV
applications since each PV module can act as a separate DC source for each cascaded H-bridge module. The proposed phase
shifted H-bridge multi-level topology offers advantages such as operation at a lower switching frequency and a lower current
ripple when compared to conventional two level topologies. It is also shown that low ripple sinusoidal current waveforms are
generated with a unity power factor. The control algorithm permits the independent control of each DC link voltage with a
maximum power point for each string of PV modules. The use of the controller area network (CAN) communication protocol for
H-bridge multi-level inverters, along with localized PWM generation and PV voltage regulation are implemented. It is also
shown that the expansion and modularization capabilities of the H-bridge modules are improved since the individual inverter
modules operate more independently. The proposed topology is implemented for a three phase 240kW multi-level PV power
conditioning system (PCS) which has 40kW H-bridge modules. The experimental results show that the proposed topology has good performance.
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