| Aiming at the problem of insufficient power and poor stability of single-channel grid-connected micro-inverter,this paper studies the high-power and high-stability micro-inverters,designed a single-stage two-way interleaved flyback grid-connected micro inverter based on MC56F84766 DSP as the control core.In order to achieve DC-DC,DC-AC conversion,and finally converts the converted AC power into the power grid,this inverter uses a flyback circuit as the main hardware topology,cooperating with the polarity reversal bridge topology composed of MOS transistors and thyristors.This article used transformer isolation to divide the entire micro-inverter system into primary and secondary sides.The two parts cooperated with each other through optocoupler communication,which improved the safety and reliability of the micro-inverter and reduced the operation and maintenance costs of the micro-inverter.In terms of hardware,the topology structure of each circuit module was designed,and the parameter selection of main components was given.In terms of software,this paper adopted the peak current modulation strategy of BCM(critical current mode)/ DCM(intermittent current mode)dual mode control,and proposed an improved MPPT algorithm without current detection,which improved the working efficiency of the micro inverter.In addition,in view of the inverter’s inability to quickly phase lock,slow information interaction and islanding,this paper respectively proposed the dq rotating coordinate system’s phase locking algorithm,power line carrier communication algorithm and anti-islanding strategy algorithm,which realized the rapid interconnection of the micro inverter,real-time communication and safe off-grid.Finally,through the platform built in the laboratory,the actual output power of the prototype was measured to be 560 W,the total harmonic value of the prototype was 2.123%,and the output efficiency value was up to 96%.The feasibility and effectiveness of the dual micro-inverter was verified. |
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