US 12,476,549 B2
Micro inverter, photovoltaic system and control method
Qiaodi Chen, Hefei (CN); Yu Gu, Hefei (CN); Hao Wang, Hefei (CN); Jun Xu, Hefei (CN); and Zichen Wang, Hefei (CN)
Assigned to Sungrow Power Supply Co., Ltd., Hefei (CN)
Filed by Sungrow Power Supply Co., Ltd., Hefei (CN)
Filed on Nov. 2, 2023, as Appl. No. 18/500,885.
Claims priority of application No. 202211441143.7 (CN), filed on Nov. 17, 2022.
Prior Publication US 2024/0170965 A1, May 23, 2024
Int. Cl. H02M 3/335 (2006.01); H02J 3/18 (2006.01); H02M 7/5387 (2007.01)
CPC H02M 3/33576 (2013.01) [H02J 3/1878 (2013.01); H02M 3/33569 (2013.01); H02M 3/33584 (2013.01); H02J 2300/24 (2020.01); H02J 2300/26 (2020.01); H02M 7/53871 (2013.01)] 8 Claims
OG exemplary drawing
 
5. A photovoltaic system, comprising a micro inverter and at least one photovoltaic component, wherein
an input terminal of the micro inverter is connected to the at least one photovoltaic component,
the micro inverter comprises a controller, a primary H-bridge, a transformer, a bi-directional switch arm, and a capacitor arm,
an input terminal of the primary H-bridge is connected to the at least one photovoltaic component;
two output terminals of the primary H-bridge are connected to two terminals on a primary side of the transformer, respectively;
two terminals on a secondary side of the transformer are connected to an intermediate terminal of the bi-directional switch arm and an intermediate terminal of the capacitor arm, respectively;
the bi-directional switch arm and the capacitor arm are connected in parallel; and
the controller is configured to:
determine a reactive current based on a grid voltage, an equivalent capacitance of an output terminal of the micro inverter and a grid angle;
add the reactive current to a given current to generate an internal phase-shift angle and an external phase-shift angle from a new given current obtained through the addition, wherein the internal phase-shift angle refers to a phase-shift angle between two arms of the primary H-bridge and the external phase-shift angle refers to a phase-shift angle between the primary H-bridge and the bi-directional switch arm;
wherein the controller is configured to: determine the reactive current based on a d-axis component of the grid voltage, an angular frequency of the grid voltage, the equivalent capacitance of the output terminal of the micro inverter, and a cosine value of the grid angle, and
wherein the d-axis component of the grid voltage and the angular frequency of the grid voltage are obtained through a phase locked loop.