US 12,149,168 B1
T-type LCL resonant converter and its soft switching modulation method under full power range
Song Hu, Changshu (CN); Rui Wang, Changshu (CN); Huigang Xu, Changshu (CN); Jicheng Liu, Changshu (CN); and Yong Yang, Changshu (CN)
Assigned to Changshu Institute of Technology, Changshu (CN)
Filed by Changshu Institute of Technology, Changshu (CN)
Filed on Mar. 20, 2024, as Appl. No. 18/611,676.
Application 18/611,676 is a continuation of application No. PCT/CN2024/081134, filed on Mar. 12, 2024.
Claims priority of application No. 202310720544.4 (CN), filed on Jun. 19, 2023.
Int. Cl. H02M 3/00 (2006.01); H02M 1/00 (2006.01); H02M 3/335 (2006.01)
CPC H02M 3/01 (2021.05) [H02M 1/0058 (2021.05); H02M 3/33573 (2021.05); H02M 3/33576 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A soft switching modulation method for a T-type inductor-capacitor-inductor (LCL) resonant converter under a full power range, wherein the T-type LCL resonant converter is used, and the T-type LCL resonant converter comprises a primary side full bridge, a resonant tank, a high-frequency transformer, and a secondary side half bridge connected in that order; the primary full bridge comprises a first switching transistor (S1), a second switching transistor (S2), a third switching transistor (S3), and a fourth switching transistor (S4); the first switching transistor, the second switching transistor, the third switching transistor, and the fourth switching transistor form a full bridge inverter circuit; the resonant tank comprises a first resonant inductor (L1), a second resonant inductor (L2), and a resonant capacitor (C) disposed at a primary side; the first resonant inductor is connected to the second resonant inductor; the first resonant inductor is connected to a first connection point of the primary side full bridge; an end of the resonant capacitor is connected to a connection point between the first resonant inductor and the second resonant inductor; another end of the resonant capacitor is connected to a second connection point of the primary side full bridge; a turn ratio of the high-frequency transformer is 1:n, wherein “n” is defined; the secondary side half bridge comprises a fifth switching transistor (S5) and a sixth switching transistor (S6); the fifth switching transistor, the sixth switching transistor, a first equalizing capacitor (Co1), and a second equalizing capacitor (Co2) form a half bridge rectifier circuit; and the soft switching modulation method comprises the following steps:
step S01: in a cycle, adjusting pulse widths of the first switching transistor, the second switching transistor, the third switching transistor, and the fourth switching transistor to obtain a high-frequency alternating voltage (vab) of the primary side with a symmetrical waveform having three electrical levels, an amplitude equal to Vin, an adjustable positive pulse width, and an adjustable negative pulse width; in the cycle, adjusting pulse widths of the fifth switching transistor and the sixth switching transistor to obtain a high-frequency alternating voltage (vcd) of the secondary side with a square waveform having two electrical levels, an amplitude equal to 0.5 Vout, a constant positive pulse width equal to π, and a constant negative pulse width equal to π; and Vin represents an input voltage and Vout represents an output voltage; and
step S02: adjusting a current phase of a first current (i1) of the first resonant inductor to (π−α)/2, thereby enabling the T-type LCL resonant converter to achieve soft switching operations of the first switching transistor, the second switching transistor, the third switching transistor, the fourth switching transistor, the fifth switching transistor, and the sixth switching transistor under the full power range; wherein α represents an angle that makes the first switching transistor and the fourth switching transistor be turned on simultaneously.