New start-up schemes for isolated full-bridge boost converters
06 Feb 2000-Vol. 1, pp 309-313
TL;DR: Two new start-up schemes for isolated full-bridge boost converters are proposed and their control timing is investigated, which is compatible with the PWM control timing for the normal boost mode operation.
Abstract: Two new start-up schemes for isolated full-bridge boost converters are proposed in this paper. The control timing for each scheme, which is compatible with the PWM control timing for the normal boost mode operation, is investigated. Design considerations on the relationships between the turns ratios of the boost choke windings and the main transformer windings, and its effects on the operation of the converter, are studied. The two proposed start-up schemes are experimentally verified on a 1.6 kW, 12 V/288 V prototype.
Citations
More filters
TL;DR: A new design approach achieving very high conversion efficiency in low-voltage high-power isolated boost dc-dc converters is presented, demonstrating that an extensive interleaving of primary and secondary windings is needed to avoid high winding losses.
Abstract: A new design approach achieving very high conversion efficiency in low-voltage high-power isolated boost dc-dc converters is presented. The transformer eddy-current and proximity effects are analyzed, demonstrating that an extensive interleaving of primary and secondary windings is needed to avoid high winding losses. The analysis of transformer leakage inductance reveals that extremely low leakage inductance can be achieved, allowing stored energy to be dissipated. Power MOSFETs fully rated for repetitive avalanches allow primary-side voltage clamp circuits to be eliminated. The oversizing of the primary-switch voltage rating can thus be avoided, significantly reducing switch-conduction losses. Finally, silicon carbide rectifying diodes allow fast diode turn-off, further reducing losses. Detailed test results from a 1.5-kW full-bridge boost dc-dc converter verify the theoretical analysis and demonstrate very high conversion efficiency. The efficiency at minimum input voltage and maximum power is 96.8%. The maximum efficiency of the proposed converter is 98%.
303 citations
Cites background or methods from "New start-up schemes for isolated f..."
...Although, as explained previously, most of the solutions listed here can be used for reducing inrush current during startup, the preferred solution is the method of “pumping” the converter during the charging of the output capacitors [24]....
[...]
...inductor and connected to either output [24] [scheme 2)],...
[...]
...series of narrow pulses in “buck mode,” as described in [24] [scheme 1)]....
[...]
TL;DR: The proposed converter has no startup problem and no high voltage spikes on the switches, which otherwise are inherent for current- and voltage-fed-type bidirectional converters, and is easy to achieve soft switching by proper control and design.
Abstract: This paper presents a novel topology named forward-flyback bidirectional DC-DC converter (BDC), which is a hybrid of forward and flyback converters The windings of forward and flyback transformers are connected in series on the primary side and in parallel on the secondary side The proposed converter has no startup problem and no high voltage spikes on the switches, which otherwise are inherent for current- and voltage-fed-type bidirectional converters It is easy to achieve soft switching by proper control and design The built-in flyback transformer acts as a filter inductor, so the current ripple is smaller than flyback BDCs In this paper, the operation principles and characteristics of the proposed topology are analyzed in detail The advantages aforementioned are verified with experimental results of a 300-W prototype
162 citations
Cites background from "New start-up schemes for isolated f..."
..., lack of self-starting capability and high voltage spikes on the switches [9], [10]....
[...]
TL;DR: In this article, the authors classified all the topologies of the impedance-source galvanically isolated dc-dc converters according to the element that transfers energy from the input to the output: a transformer, a coupled inductor, or their combination.
Abstract: Impedance-source converters, an emerging technology in electric energy conversion, overcome limitations of conventional solutions by the use of specific impedance-source networks. Focus of this paper is on the topologies of galvanically isolated impedance-source dc–dc converters. These converters are particularly appropriate for distributed generation systems with renewable or alternative energy sources, which require input voltage and load regulation in a wide range. We review here the basic topologies for researchers and engineers, and classify all the topologies of the impedance-source galvanically isolated dc–dc converters according to the element that transfers energy from the input to the output: a transformer, a coupled inductor, or their combination. This classification reveals advantages and disadvantages, as well as a wide space for further research. This paper also outlines the most promising research directions in this field.
161 citations
Cites background from "New start-up schemes for isolated f..."
...Another issue of the CSC, the inrush current during the start-up at low output voltage, requires auxiliary start-up circuits to be implemented [20]....
[...]
TL;DR: This paper begins with a review of the operation of the ZVS active-clamp converter and that of ZCS converters in general; the advantages and disadvantages of each approach are stated; and a comparison of the performance of the two converters is made.
Abstract: Pulse width modulation (PWM) current-fed full-bridge dc-dc boost converters are typically used in applications where the output voltage is considerably higher than the input voltage. In this paper, a comparison is made between two converter topologies of this type-the standard zero-voltage switching (ZVS) active-clamp topology and a new zero-current switching (ZCS) topology. This paper begins with a review of the operation of the ZVS active-clamp converter and that of ZCS converters in general; the advantages and disadvantages of each approach are stated. A new ZCS-PWM current-fed dc-dc boost full-bridge converter is then introduced. The operation of the new converter is explained and analyzed, and a procedure for the design of its key components is given and demonstrated with an example. Experimental results obtained from a prototype of a ZVS active-clamp converter and the new ZCS converter are presented. Finally, a comparison of the performance of the two converters is made and conclusion based on this comparison is stated.
133 citations
TL;DR: In this paper, a three-phase high power current-fed DC/DC converter with an active clamp was designed for use in the interface between a lowvoltage fuel-cell source and a high-voltage DC bus for inverters.
Abstract: This paper focuses on a new three-phase high power current-fed DC/DC converter with an active clamp. A three-phase DC/DC converter with high efficiency and voltage boosting capability is designed for use in the interface between a low-voltage fuel-cell source and a high-voltage DC bus for inverters. Zero-voltage switching in all active switches is achieved through using a common active clamp branch, and zero current switching in the rectifier diodes is achieved through discontinuous current conduction in the secondary side. Further, the converter is capable of increased power transfer due to its three-phase power configuration, and it reduces the RMS current per phase, thus reducing conduction losses. Moreover, a delta-delta connection on the three-phase transformer provides parallel current paths and reduces conduction losses in the transformer windings. An efficiency of above 93% is achieved through both improvements in the switching and through reducing conduction losses. A high voltage ratio is achieved by combining inherent voltage boost characteristics of the current-fed converter and the transformer turns ratio. The proposed converter and three-phase PWM strategy is analyzed, simulated, and implemented in hardware. Experimental results are obtained on a 500-W prototype unit, with all of the design verified and analyzed.
113 citations
Additional excerpts
...In order to achieve a high voltage ratio while limiting the overshoot in the turn-off voltage caused by the leakage inductance, a current-fed dc/dc converter with an active clamp has been introduced in the push–pull topology [3] and full-bridge topology [4]–[6] for all single–phase application....
[...]
References
More filters
22 Oct 1998
TL;DR: In this article, the need of a bi-directional DC to DC converter for a fuel cell system was described, and various combinations of current-fed and voltage-fed converters were explored for the application of different voltage levels.
Abstract: This paper first describes the need of a bi-directional DC to DC converter for a fuel cell system. Various combinations of current-fed and voltage-fed converters are explored for the application of different voltage levels. With a preliminary study, putting current-fed on low-voltage side and voltage fed on high voltage side indicated higher efficiency than the other way around. Two low-side circuit topologies were then selected for hardware implementation. One is the L-type half-bridge current-fed converter, and the other is full-bridge current-fed converter. The high-side circuit topology is fixed with a full-bridge voltage-fed converter. Two systems were built and tested to full power. The results indicate that the combination with the full-bridge converter on the low-voltage side is more efficient than the combination with the L-type half-bridge converter on the low-voltage side for both charging and discharging modes.
224 citations
23 Jun 1996
TL;DR: In this paper, a full-bridge, active-clamp boost converter is proposed for single-phase high power PFC applications and applications requiring transformer isolation, which serves to limit bridge switch turn-off voltage overshoot and enable the energy stored in the transformer leakage inductance to be used for zero-voltage switching.
Abstract: A new full-bridge, active-clamp boost converter is proposed for single-phase high power PFC applications and applications requiring transformer isolation. The active-clamp network serves to limit bridge switch turn-off voltage overshoot and enable the energy stored in the transformer leakage inductance to be used for zero-voltage switching. PWM phase-shift control of the bridge switches is utilized to obtain zero-current switching for two of the four bridge switches. Simulation results are presented which verify the principle of operation.
188 citations
TL;DR: In this paper, the authors present the analysis, design, and experimental results of 500 W single stage and 600 W interleaved active clamp flybacks used for power factor correction in power convertor topologies.
Abstract: Flyback derived power convertor topologies have long been attractive because of their relative simplicity when compared with other topologies used in low-power applications. Incorporation of active clamp circuitry provides the additional benefit of recycling transformer leakage energy while minimizing switch voltage stress. This paper presents the analysis, design, and experimental results of 500 W single stage and 600 W interleaved active clamp flybacks used for power factor correction. Several practical issues, including the application of charge control, the use of mixed power devices, and a solution to the hold-up time problem are discussed and experimentally verified.
137 citations
23 Jun 2000
TL;DR: In this article, the PWM control, design and implementation issues of the bi-directional dual full-bridge DC/DC converter with a unified soft switching scheme and soft start capability are presented in this part of the two-part sequel.
Abstract: The PWM control, design and implementation issues of the bi-directional dual full-bridge DC/DC converter with a unified soft-switching scheme and soft-start capability, which was proposed in a companion paper, are presented in this part of the two-paper sequel. Test results on a 5 kW prototype converter, which is connected between a 12 V battery and a high voltage bus, and targeted for alternative energy applications, validate the secure operation, high reliability and superior efficiency of the proposed converter topology.
92 citations
01 Jun 1981
TL;DR: Four modes of operation are possible for the basic push-pull current-fed converter and various design options and selection guidelines are presented along with experimental results.
Abstract: Four modes of operation are possible for the basic push-pull current-fed converter. Each mode is analyzed, circuit waveforms are explained, and relationships that influence the converter design are developed. Various design options and selection guidelines are presented along with experimental results.
47 citations