Power Electronics for Renewable Energy Systems, Transportation and Industrial Applications

Chapter 24Impedance Source Inverters

Yushan Liu^1,2, Haitham Abu-Rub¹ and Baoming Ge^2,3

¹Department of Electrical and Computer Engineering, Texas A&M University at Qatar, Doha, Qatar

²School of Electrical Engineering, Beijing Jiaotong University, Beijing, China

³Department of Electrical Engineering, Texas A&M University, Texas, USA

24.1 Multilevel Inverters

One of the most suitable power architectures for a photovoltaic (PV) system is the multilevel inverter. Although there are many conventional two-level inverters available in this area, the multilevel inverter provides the following advantages: (1) reduced device voltage stress; (2) negligible total harmonics in the voltage waveforms; (3) smaller output filter size; (4) greater efficiency [1–4]; and (5) an implementation of the so-called distributed maximum power point tracking (DMPPT) [5–7]. The fifth advantage extends the MPPT to each panel of a PV system by avoiding series-connected PV arrays, which are often used with the conventional two-level inverter. This minimizes power loss even when mismatching conditions occur. Among the following three main families of multilevel converter: diode-clamped, capacitor-clamped, and cascaded H-bridge, the latter is usually considered in the literature for PV applications [8, 9].

24.1.1 Transformer-Less Technology

To interface the low-voltage (LV) output of an inverter to the grid, a bulky low-frequency transformer is necessary, which involves large size, less efficiency, loud acoustic ...