Packed U-Cell (PUC) converter has been introduced as a 7-level converter in early 2008. Since then, different analysis and projects have been performed on, including various applications such as inverter and rectifier, linear and nonlinear voltage controllers. In this paper, authors try to do a detail review on this topology covering all aspects like topology design in single and three-phase, operation concepts, switching sequences for different multilevel voltage waveform generation, modelling and etc. It is shown that this topology can be comparable to popular multilevel converters (CHB and NPC) in terms of device counts and applications. Moreover, some performed and published works about the PUC are mentioned to show its different industrial applications and some other converter topologies derived based on the PUC. Experimental results are provided to show the good performance of PUC converter in several applications.
- Packed U-Cell
- Multilevel converter
- Active power filter
- Active rectifier
- Power quality
Fig. 1. Three-phase 3-wire/4-wire configuration of PUC inverter
EXPECTED SIMULATION RESULTS:
Fig. 2. Test results of a 7-Level PUC rectifier
Fig. 3. Test results of a sensor-less 5-Level PUC standalone inverter
Fig. 4. Test results of a Sensor-less 5-Level PUC grid-connected inverter
Fig. 5. Experimental results of 5-level PUC converter as STATCOM
Fig. 6. Three-phase 5-level PUC inverter voltage and current waveforms
PUC converter generates various voltage levels based on the voltage ratio of its two DC links similar to the CHB topology, while using fewer components. It is an interesting topology in inverter mode due to using only one isolated DC source. It is also attractive in rectifier application because of generating dual output DC terminal in boost and buck mode. As shown in this paper, the PUC converter can be a good candidate for all modes of operation like standalone/grid-connected inverter and rectifier in various applications including PV systems, active filters, wind turbine, electric transportation, battery chargers, MMC, etc.
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