Soft‐switching DC–DC converter with controllable resonant tank featuring high efficiency and wide voltage gain range

Abstract

A two-mode resonant DC-DC converter with auxiliary switch (named as sLLC-C) has been presented. Two simple structural circuits (namely LLC and LLCC) are integrated into one topology with only two magnetic cores, through the topological transformation method. The proposed converter successfully inherits the advantages of the above two circuits, while avoiding their drawbacks as well. At the rating condition, it functions as an LLC circuit, and thus high conversion efficiency is easily obtained. The LLCC working mode is called automatically once the input voltage increases. In such a way, within a limited frequency range, the voltage gain range is effectively extended. A detailed parameter design is given to help achieve desirable performances. Finally, experiments are carried out to validate the feasibility and correctness of the proposed sLLC-C converter. The output voltage is maintained at 400 V, even if the input voltage varies in the range of 150-400 V. Besides, the preferable soft-switching characteristics are ensured for both the power switches and secondary-side diodes. The maximum efficiency of 97.3% is achieved. Thus, wide voltage gain range and high conversion efficiency are acquired simultaneously. These performances make the proposed converter well appropriate for the fuel cell generation applications.

Survey of Topology Morphing Control Techniques for Performance Enhancement of Galvanically Isolated DC-DC Converters

“…Resonant Tank [79], [80] Multi-Track Architect [81], [82] Voltage range extension Light-load performance enhancement Static reconfiguration of the input or output stages is a typical TMC approach. However, more advanced techniques are available too.…”

A study on combined multi‐resonance converter for on‐board charging of electric vehicles

“…The disadvantage of the LLC converters is that to achieve a wider output voltage range, a wide switching frequency range is required, which will result in low overall efficiency of the converter and an uneven efficiency curve 12 . In order to flatten the efficiency curve, new schemes for improving the converter structure and the control strategy are studied in the literature 13–19 …”

“…Multi‐resonant converters have been studied in the literature 13–15 . A novel multi‐resonant DC‐DC converter is proposed in Zhao et al 13 Compared with traditional LLC converters, the third harmonic of the multi‐resonant DC‐DC converter is used to transmit active power and reduce primary reactive power loss in order to increase the efficiency.…”

“…Moreover, using the notch filter function makes the converter more reliable. Author et al (2020) proposed a multi‐resonant converter with bidirectional switch, which achieves a wide input voltage range and improved efficiency by switching between the two modes of the converter 14 . A multi‐resonant converter used in a bidirectional DC‐DC was proposed in Zhao et al, 15 which enables ZVS in the entire load range regardless of the converter's mode of operation, and transmits both fundamental and third harmonics, therefore improving efficiency.…”

Non‐isolated LLC resonant converter with suppressed circulating current and automatic resonant frequency matching capability

“…In [20], a dual-mode soft-switching DC-DC converter with the controllable resonant tank is reported. Through the integration of an auxiliary capacitor and bidirectional switch in the resonant circuit, the converter shows an improve efficiency and flexibility.…”