Voltage Doubling Wide Gain LLC Resonant Converter Controlled by Constant Frequency and Variable Duty Cycle
The traditional LLC resonant converter has an excessively wide switching frequency operating range when applied in a wide voltage range,and the performance of voltage regulation is poor.To solve the above problems,a pulse width modulation strategy with constant frequency and variable duty cycle is pro-posed,which is based on a full bridge LLC resonant converter with voltage doubling structure.The input voltage of the resonant tank is changed by changing the duty ratio of the primary side switch network in full bridge and the half bridge;At the same time,under the control of secondary side bidirectional switch,the proportion of the rectifier network working in the full bridge and voltage doubler rectification modes can be changed,and finally achieve a quadruple voltage gain range.Compared with pulse frequency modu-lation,the influence of converter load and magnetizing inductance on the gain is weaker,and a larger mag-netizing inductance can be selected to reduce the circulating current.The primary side switch of the con-verter realizes the ZVS turn-on,and the rectifier diode realizes the ZCS turn-off.Finally,simulation and experiment verify the feasibility of the converter under this modulation strategy.
variable duty cycleresonant converterfixed frequency controlwide voltagesoft switching
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维普
