Three-phase micro-inverter

Single phase solar micro-inverters aim at the residential and commercial rooftop applications. It would be advantageous to extend the micro-inverter concept to large size PV installations such as MW-class solar farms where three-phase AC connections are used. Unlike single-phase systems, where a bulky power decoupling capacitor is required to buffer the fluctuated injected power,^[1] balanced three-phase system draws constant power from the three-phase micro-inverter, which will minimize the DC link capacitance and allow for the long lifetime capacitors to be used.^[2] More specifically, the three-phase distributed AC micro-inverter architecture would offer the following advantages:^[3]

• Ease of installation through flexible and modular solar farm design: Micro-inverters would greatly reduce installation costs associated with wiring, cabling, DC bus disconnections, and large size inverters since each micro-inverter would generate AC power that could be directly coupled to the grid;
• Improved reliability by effectively reducing the number of components per watt compared to that of equivalent single-phase AC modules;
• Reduced in dollars per watt since one inverter is now amortized over higher level of power;
• Finally eliminated the need of an expensive custom AC cable that is required to balance the number of single phase inverters per phase.

References

1. Li, Quan; P. Wolfs (2008). "A Review of the Single Phase Photovoltaic Module Integrated Converter Topologies with Three Different DC Link Configurations". IEEE Trans. on Power Electronics 23 (3): 1320–1333. doi:10.1109/tpel.2008.920883.
2. Chen, Lin; A. Amirahmadi; Q. Zhang; N. Kutkut; I. Batarseh. "Design and Implementation of Three-phase Two-stage Grid-connected Module Integrated Converter". IEEE Transactions on Power Electronics 29 (8): 3881–3892. doi:10.1109/tpel.2013.2294933.
3. Amirahmadi, Ahmadreza; H. Hu; A. Grishina; Q. Zhang; L. Chen; U. Somani; I. Batarseh (2014). "ZVS BCM Current Controlled Three-Phase Micro-inverter". IEEE Transactions on Power Electronics 29 (4): 2124–2134. doi:10.1109/tpel.2013.2271302.