A three-phase grid tied micro-inverter using controlled-based soft switching
A group of UCF researchers have developed a three-phase micro-inverter for low power applications, specifically batteries, solar panels, or fuel cells, with higher power density and efficiency. The entirely new control approach eliminates the need for expensive additional parts often required of hard switched inverters, such as SiC diodes or additional inductors, thereby increasing the power density and solving the light load efficiency problem. The three-phase grid tied power micro-inverter provides a three -level control scheme. Phase skipping control is one of the control schemes, and it selectively injects power through each phase, ensuring that the phases’ received power operates at a greater percentage of a load capacity, thus significantly improving the micro-inverter’s power efficiency. For the first time, a power inverter employs a hybrid zero-voltage switching (ZVS) current control technique for a switching inverter and soft switched controls which increases the switching frequency and yields higher power conversion efficiency. Now, achieve power conversion with lower costs, higher reliability, and higher power density.
Micro-inverter use has been limited to small scale, single phase residential and commercial PV installations. By extending the micro-inverter concept to large size PV installation where three-phase AC connection is used, advantages such as individual variable frequency maximum power point tracking (MPPT) to determine a switching frequency for a resonant power converter, redundant system architecture, ease of installation, removal of unreliable electrolytic capacitors, and less DC distribution losses can be gained. To make the idea of PV farm architecture based on three-phase micro-inverters feasible, a high efficiency, low cost, high reliability, high compact micro-inverter was designed and built. Invented three-phase micro-inverter can be used for any PV power plant, from small scale to proof applications for commercial building to large scale PV power plants.
- Peak efficiency of 96 percent
- Eliminate the need of electrolytic capacitors
- New MPPT method for resonant converter
- New control based soft switching method with no additional cost or component
- Solves the light load efficiency problem
- Residential solar systems
- Commercial building solar systems
- PV power plants
- Fuel cells
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