Bidirectional DC-DC Resonant Converter With Wide Input and Output Voltage Range

Abstract

Variable frequency controlled LCLL resonant converter when step-down, the narrow voltage gain range and wide switching frequency change range limit its step-down ability, but the step-up ability is excellent; While phase shift controlled LCLL resonant converter when step-down, because of the wide voltage gain Range and fixed switching frequency have a excellent step-down ability, but the step-up ability is poor. In order to realize that the bidirectional LCLL resonant converter has great buck-boost capability in a narrow switching frequency range, a hybrid control method of variable frequency boost and phase shift buck is proposed by integrating the respective control advantages of variable frequency and phase shift. Under this control strategy, the converter not only achieves the regulated output during bidirectional operation mode, but also has excellent buck-boost capability and soft switching characteristics. The working principle and characteristics of bidirectional LCLL resonant converter under hybrid control strategy are analyzed in detail in the article. And a 500W experimental prototype was designed to verify the performance of the bidirectional LCLL resonant converter under hybrid control. The experimental results verified the feasibility of the control strategy and the excellent buck-boost capability.