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Technical Dialogue

Resonant Converters

D02.9 - Start-Up Techniques and Universal Closed Loop Control of Immittance Network based Resonant Converter

Thursday, March 20, 2025
11:30 AM - 1:30 PM ET
Location: Level One, Hall A3
Immittance based resonant topologies have recently gained attention for on/off board charging due to their bidirectional nature owing to the symmetry of the resonant tank, use of simple phase shift control for power flow and no requirement for burst mode control at light loads. However, due to fixed frequency operation at or close to the resonant point, traditional start-up control techniques with variable frequency based resonant converters are not applicable. This paper therefore proposes techniques to handle start-up for immittance converters. Additionally, to cater to wide DC bus input voltage range, a multi-level stacked half bridge converter is used as primary side, for which a universal closed loop controller with DC bus voltage balancing is proposed. The start-up and closed loop schemes are verified on a 6.6 kW on board charger prototype. As an example, the LCL-T based resonant converter will be used for demonstration