Soft‐switching converter with low circulating current and wide range of ZVS turn‐on

Abstract

SUMMARYIn this paper, a new hybrid dc-dc converter with low circulating current within the freewheeling interval, wide range of zero-voltage switching and reduced output current ripple is presented. The proposed hybrid circuit includes two three-level pulse-width modulation converters and a series resonant converter with the shard lagging-leg switches. Series resonant converter is operated at fixed switching frequency (close to series resonant frequency) to extend the zero-voltage switching range of lagging-leg switches. The output of series resonant converter is connected to the secondary sides of three-level converters to produce a positive rectified voltage instead of zero voltage. Hence, the output inductances can be reduced. The reflected positive voltage is used to decrease the circulating current to zero during the freewheeling interval. Therefore, the circulating current losses in three-level converters are improved. Finally, experiments are presented for a 1.44 kW prototype circuit converting 800 V input to an output voltage 24 V/60A. Copyright

An integrated controller for high‐frequency LCLC resonant inverter with phase‐shifted control and frequency regulation

“…The ZVS feature of the full-bridge resonant inverter has been examined in [11]. The resonant current of series branch has enough energy to discharge the parallel capacitor of turn-on switches and charge the parallel capacitor of turn-off switches [12,13]. Thus, the ZVS condition is resulted by…”

“…Consequently, the high-frequency power source has to provide high-quality sinusoidal output with the strong robustness against the exogenous perturbations. In addition to load estimation, some studies focus on the design and optimization of high-frequency power source that is the most effective method to solve multiple loads and voltage distortion resulting from the nonlinearity of source and/or converter [10][11][12][13][14][15][16][17].…”

“…The connection impedance (R c , L c ) is deliberately placed to represent the connection cable. Great efforts have been performed to improve the output performance of resonant inverter from modulation method to control strategy [11][12][13][14][15][16][17][18][19]. Furthermore, an effective control scheme is essential for fourth-order LCLC resonant inverter operated as a power source of HFAC vehicle application.…”

A new design strategy for DC/DC LLC resonant converter: Concept, modeling, and fabrication

“…The SPRC has two general types: LLC and LCC. SRC has some defects such as lack of regulation in light loads despite ZVS in switching which needs additional control system and this is not simple; however, in Lin and Nian, this topology has been used for soft‐switching in a converter with shard lagging‐leg switches and fixed switching frequency. Existence of high circulating energy in resonant tank of SRC that can be made by the high difference between the input and output voltage of converter is the other defect of SRC.…”

“…The SPRC has two general types: LLC and LCC. SRC has some defects such as lack of regulation in light loads despite ZVS in switching which needs Nomenclature: V in(nom) , Nominal input voltage; V in(min) , Minimum input voltage; V out , Output voltage; P out , Output power; V f , Forward voltage of diode; V pri , Transformer primary voltage; M min , Resonant tank minimum gain; M max , Resonant tank maximum gain; M, Resonant tank maximum output gain; R ac , Efficient load resistance referred to primary side; n, Turns ratio; η, Efficiency; L r , Series inductance; L m , Parallel inductance; C r , Series capacitor; L lk1 , Primary leakage inductance; L lk2 , Secondary leakage inductance additional control system and this is not simple 19 ; however, in Lin and Nian, 20 this topology has been used for softswitching in a converter with shard lagging-leg switches and fixed switching frequency. Existence of high circulating energy in resonant tank of SRC that can be made by the high difference between the input and output voltage of converter is the other defect of SRC.…”