Analysis and design of LLC resonant converter with variable magnetising inductance control. Issue 16 (1st December 2020)

• Record Type: Journal Article
• Authors: Wei, Yuqi; Luo, Quanming; Chen, Jian; Alan Mantooth, Homer
• Is Part Of: IET power electronics. Volume 13:Issue 16(2020)
• Page Start: 3528
• Page End: 3536
• Publication Date: 2020-12-01
• Subjects: switching convertors -- pulse frequency modulation -- driver circuits -- zero current switching -- DC‐DC power convertors -- resonant power convertors -- power capacitors -- zero voltage switching; wide switching frequency operating range -- output voltage -- PFM LLC resonant converters -- optimisation -- magnetic components -- gate driver circuitry -- variable switching frequency -- electro‐magnetic interference performance -- independent control -- multiple‐output applications -- frequency operation -- variable magnetising inductance control strategy -- VMIC control strategy -- operating switching frequency -- primary switch -- resonant frequency operating point -- zero current turn‐off operation -- operational principles -- industrial applications -- conventional pulse frequency modulation controlled LLC resonant converter -- power 200.0 W; Power electronics -- Periodicals; 621.31705
• DOI: 10.1049/iet-pel.2020.0007
• Languages: English
• ISSNs: 1755-4535

Abstract

Abstract : A conventional pulse frequency modulation (PFM) controlled LLC resonant converter requires a wide switching frequency operating range to regulate the output voltage. There are some disadvantages of PFM LLC resonant converters: (i) the design and optimisation of magnetic components and gate driver circuitry are challenging; (ii) due to the variable switching frequency operating range, electro‐magnetic interference performance of the converter is degraded; (iii) efficiency degradation; (iv) inability to achieve independent control in multiple‐output applications. To address the above‐mentioned problems and achieve fixed switching frequency operation, a variable magnetising inductance control (VMIC) strategy is proposed. In the proposed VMIC control strategy, the operating switching frequency of the primary switch is fixed and the duty cycle remains constant at 0.5. At the resonant frequency operating point, the output voltage is independent of both the magnetising inductance and load. In addition, the zero current turn‐off operation of the secondary rectifier requires that the switching frequency be designed below the resonant frequency. The operational principles and design considerations of the LLC resonant converter with VMIC are presented. Experimental results from a 200 W prototype are presented to validate the theoretical analysis and the effectiveness of the proposed VMIC control strategy.