Interleaved ZVS Resonant Converter with a Parallel-Series Connection

Abstract

This paper presents an interleaved resonant converter with a parallel-series transformer connection in order to achieve ripple current reduction at the output capacitor, zero voltage turn-on for the active switches, zero current turn-off for the rectifier diodes, less voltage stress on the rectifier diodes, and less current stress on the transformer primary windings. The primary windings of the two transformers are connected in parallel in order to share the input current and to reduce the root-mean-square (rms) current on the primary windings. The secondary windings of the two transformers are connected in series in order to ensure that the transformer primary currents are balanced. A full-wave diode rectifier is used at the output side to clamp the voltage stress of the rectifier diode at the output voltage. Two circuit modules are operated with the interleaved PWM scheme so that the input and output ripple currents are reduced. Based on the resonant behavior, all of the active switches are turned on under zero voltage switching (ZVS), and the rectifier diodes are turned off under zero current switching (ZCS) if the operating switching frequency is less than the series resonant frequency. Finally, experiments with a 1kW prototype are described to verify the effectiveness of the proposed converter.

Modified LLC resonant converter with secondary paralleled bidirectional switch for applications with hold‐up time requirement

“…Then apart from achieving the switches' soft-switching as (17), the magnetising inductance L m of the conventional LLC converter also needs to be reduced to provide the required voltage gain in (18) during the hold-up time [18][19][20][21][22][23][24]. However, as it can be seen from (15), the voltage gain M of the proposed converter with PS control is independent of L m . Just determined by (17), the converter has a larger L m than the conventional one.…”

“…Then to make a fair comparison, the proposed converter has the same resonant tank parameters except for the magnetising inductance L m . Decided by (15), the L m of the proposed converter is designed 500 µH, and is larger than the conventional one. To satisfy the hold-up time requirement in Table 1, a 200 µF capacitor with T h = 23 ms has been chosen as the link-capacitor C b .…”

“…However, a small L m results in high primary circulating current and conduction losses, and thus deteriorates the efficiency in normal operation [9][10][11][12]. Although many design methods of the resonant tank parameters have been researched to improve the efficiency, the reduced L m is still much smaller than the required one to achieve switches' ZVS turn-on [9][10][11][12][13][14][15][16].…”

Analysis and Implementation of a Half Bridge Class-DE Rectifier for Front-End ZVS Push-Pull Resonant Converters

“…These advantages result in a higher overall system efficiency. For higher power applications, paralleling DC/DC converters is a better choice than paralleling too many power MOSFETs [11], [12]. There are active paralleling techniques with the current sharing control method.…”