Voltage-Controlled Tunable Capacitor based Resonant Power Converter

The conventional resonant converters are based on fixed passive components which are required to be operated by variable switching frequency control with limited regulation capabilities under changing operating conditions. This includes the variations of load, source, and components. The variable switching frequency operation not only increases the size of the EMI and the harmonic filters but also reduces the efficiency of a converter. To address these challenges, a fixed frequency resonant power converter based on voltage-controlled tunable capacitor is proposed in this work. In the proposed converter, the capacitance of the resonant tank is varied to control the gain of the resonant converter by changing the dc control voltage across a tunable capacitor bank. Detailed analysis and design of the proposed converter, utilizing LLC resonant tank structure, for achieving high efficiency and fixed frequency operation are presented. Experimental results are presented to validate the operation and high performances of the proposed resonant converter.