A Digital Adaptive Voltage Positioning Technique for 48-1V ISOP-LLC Converter based on Bang-Bang Charge Control

In this paper, a digital adaptive voltage positioning (digital AVP) technique with fast transient response for 48-1V ISOP-LLC converter is proposed, which is featured with improving the dynamic performance of LLC converter and reducing system complexity. The proposed digital control architecture operates with Bang–Bang Charge Control (BBCC). The digital AVP concept is applied into the resonant converter, while satisfying output voltage regulation with better dynamic performance. Two digital-to-analog converters (DACs) are used instead of analog-to-digital converters (ADCs), thus significantly reducing system complexity. The control law is straightforward and no compensator is involved in the control loop, which greatly reduces the computation delay. Both the output voltage and resonant capacitor threshold voltage references are changed dynamically at DAC clock frequency to achieve fast transient response. Furthermore, dynamic reference step adjustment method is employed to reduce the high-speed requirement on reference updating clock without compromising steady-state performance. The performance of the proposed converter and control was validated in the PSIM simulation.