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In a server power system, a standby converter is required in order to provide the standby output, monitor the system's status, and communicate with the server power system. Since these functions are always required, losses from the standby converter are produced even though the system operates in normal mode. For these reasons, the losses deteriorate the total efficiency of the system. In this paper, a new structure is proposed to eliminate the losses from the standby converter of a server power supply. The key feature of the proposed structure is that the main direct current (DC)/DC converter substitutes all of the output power of the standby converter, and the standby converter is turned off in normal mode. With the proposed structure, the losses from the standby converter can be eliminated in normal mode, and this leads to a higher efficiency in overall load conditions. Although the structure has been proposed in the previous work, very important issues such as a steady state analysis, the transient responses, and how to control the standby converter are not discussed. This paper presents these issues further. The feasibility of the proposed structure has been verified with 400 V link voltage, 12 V/62.5 A main output, and a 12 V/2.1 A standby output server power system. [ABSTRACT FROM AUTHOR]

This paper presents nonisolated single-switch high step-up converters with low voltage stress. Based on the conventional flyback converter, one single-switch high step-up converter is derived. The voltage stresses on the switch and diodes are limited by using a clamping diode and voltage doubler structure. Also, to further reduce the voltage stresses of them, another single-switch high step-up converter is proposed simply by using one additional capacitor and rearranging the components. Thus, lower voltage-rated switch and diodes can be used, which results in higher efficiency. The operational principle, analysis and design considerations of each converter are presented in this paper. The validity of this study is confirmed by the experimental results from 24 V input and 250 V/125 W output prototype. [ABSTRACT FROM AUTHOR]

A new LLC series resonant converter that has a narrow switching frequency variation and reduced conduction losses is proposed in this paper. In the proposed converter, one leg of the full-bridge diode rectifier is replaced with synchronous rectifier (SR) switches. In the nominal state, the proposed converter is controlled using frequency modulation, and the SR switches are controlled using in-phase switching signals with primary side switches in order that the proposed converter can obtain a reduced conduction loss in its secondary side rectifiers. During the hold-up time which is the condition where the input voltage of the converter decreases, the SR switches are controlled using phase-shifted switching signals in order that the proposed converter can obtain a higher gain without decreasing the switching frequency. Because the proposed converter operates with a narrow switching frequency variation, a small transformer core can be selected, which results in a decreased core size and loss. Furthermore, it is possible for the proposed converter to be designed optimally in the nominal state and this results in the proposed converter exhibiting a maximized efficiency over the entire load condition. The feasibility of the proposed converter is verified with a 400-250 V input and 200 V/1.5 A output prototype. [ABSTRACT FROM AUTHOR]

The k-Q analysis of the resonant tank for an LLC series-resonant converter (SRC) is presented in this letter. In order to guarantee the LLC-SRC operating region, the k-Q design guideline of the resonant tank is proposed. [ABSTRACT FROM AUTHOR]

This paper proposes an asymmetrical half-bridge (AHB) converter with a new secondary rectifier. Due to the new rectifier stage, the proposed AHB converter has a zero dc-offset current in the transformer at any operating conditions so that the transformer core loss becomes very small compared to the conventional AHB converter. This results in higher efficiency. Besides, magnetic components can be optimally utilized because maximum flux density can be applied when designing the magnetic components. It also allows a flexible design to improve the efficiency or reduce the cost. This paper presents the operation principle and relevant analysis results of the proposed converter. A 300 W, 200-400-V input, and 50-V output laboratory prototype operating at 100 kHz is built and tested to verify the effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

A new soft-switching dc/dc converter, which can solve the drawbacks of existing phase-shifted full-bridge converters such as narrow zero-voltage-switching (ZVS) range, large circulating current, large duty-cycle loss, and a large output filter in high-voltage applications, is proposed in this paper. The proposed converter is composed of two symmetric half-bridge inverters that are placed in parallel on the primary side and are driven in a phase-shifting manner to regulate the output voltage. At the rectifier stage, two full-bridge rectifiers sharing two low-current-rating diodes are employed. This structure allows the proposed converter to have the advantages of a full ZVS range, no problems related to duty-cycle loss, no circulating current, and a significantly reduced output filter. In this paper, the circuit configuration, operation principle, and relevant analysis results of the proposed converters are presented. Experimental results on a prototype converter realized with the specification of 80-in plasma display panel sustain power module (320-385 Vdc input, 205 Vdc/5 A output) validate the theoretical analysis. [ABSTRACT FROM AUTHOR]

In this paper, the analysis and design of a three-level LLC series resonant converter (TL LLC SRC) for high- and wide-input-voltage applications is presented. The TL LLC SRC discussed in this paper consists of two half-bridge LLC SRCs in series, sharing a resonant inductor and a transformer. Its main advantages are that the voltage across each switch is clamped at half of the input voltage and that voltage balance is achieved. Thus, it is suitable for high-input-voltage applications. Moreover, due to its simple driving signals, the additional circulating current of the conventional TL LLC SRCs does not appear in the converter, and a simpler driving circuitry is allowed to be designed. With this converter, the operation principles, the gain of the LLC resonant tank, and the zero-voltage-switching condition under wide input voltage variation are analyzed. Both the current and voltage stresses over different design factors of the resonant tank are discussed as well. Based on the results of these analyses, a design example is provided and its validity is confirmed by an experiment involving a prototype converter with an input of 400-600 V and an output of 48 V/20 A. In addition, a family of TL LLC SRCs with double-resonant tanks for high-input-voltage applications is introduced. While this paper deals with a TL LLC SRC, the analysis results can be applied to other TL LLC SRCs for wide-input-voltage applications. [ABSTRACT FROM AUTHOR]

Stacking an auxiliary step-up circuit on top of a boost converter is one of the most attractive structures for nonisolated high step-up applications. In this paper, in order to avoid the large input current ripple of coupled-inductor-based circuits, an auxiliary step-up circuit is integrated via an additional transformer and its balancing capacitor. A voltage-doubler is adopted as an auxiliary step-up circuit, which is inherently suitable for high-voltage applications due to its simple structure and low-voltage stress. Moreover, the transformer leakage inductor and the balancing capacitor constitute a resonant tank so that the quasi-resonant operation makes the current sinusoidal. As a result, a reduced switch turn-off loss and reverse recovery of the diode can be expected. The proposed converter is verified with a 24 V input, 160 W - 200 V output prototype. [ABSTRACT FROM AUTHOR]

A new interleaved forward (IF) converter, adopting the series-input series-rectifier (SISR) structure with a common transformer reset circuit (CTRC), is proposed in this paper. The series-input structure distributes the switch voltage stress so that it is suitable for high-input-voltage applications. Moreover, in order to simplify the total circuit, one active-clamp circuit is shared with two forward converters as a CTRC for transformer reset. In addition, the series-rectifier structure with a common output inductor guarantees a fair current balance between the primary modules, while the interleaving technique reduces the output-filter size. All these features make the proposed SISR IF converter promising for high-input-voltage applications with a high efficiency and a simple structure. [ABSTRACT FROM AUTHOR]

An improved dual-path energy recovery circuit (ERC) using a current source and a voltage source for plasma display panel (PDP) is proposed. The proposed ERC uses the voltage source to charge a panel and the current source to discharge the panel. Thus, the proposed circuit can make the panel charge to a sustaining voltage Vs and fully discharge to 0 V, and it is possible to achieve zero-voltage switching for all switches in an H-bridge inverter and zero-current switching for all switches in the ERC. Moreover, it has less conduction and switching loss in ERC devices by the dual energy recovery paths for charging and discharging the panel. Furthermore, it has the features of canceling the gas discharge current, high performance, and the low-cost ERC components. The operation principle and features of the proposed ERC are presented in detail and verified with 42-in standard definition (SD)PDP. [ABSTRACT FROM AUTHOR]

An LLC series-resonant converter has many unique characteristics and improvements over pulsewidth-modulation topologies. However, many output capacitors are needed in parallel to satisfy an output voltage ripple and a rated ripple current of the capacitors. This paper deals with a novel two-phase interleaved LLC resonant converter using a phase of the resonant capacitor. The proposed converter satisfies low output-voltage ripple requirement and meets the rated ripple of output capacitor's current with few output capacitors. The operation and features are considered in detail, and a prototype with a 12-V-100-A output is investigated. [ABSTRACT FROM AUTHOR]

A new boost half bridge (BHB) converter is presented. It is composed of additional switch, diode and coupled winding to boost inductor of BHB converter. Using the transferring of boost inductor current to coupled winding in a short period, the cancellation of zero voltage switching (ZVS) current, which always occurs in convention one, is prevented. Therefore, the ZVS operation is easily achieved by leakage inductor current of transformer. Furthermore, since negatively build-up leakage inductor current of boost winding helps the ZYS operation throughout full load range, the excellent ZVS operation and high efficiency is achieved. [ABSTRACT FROM AUTHOR]

A new voltage doubler rectified boost-integrated half bridge converter for digital car audio amplifiers is proposed. The proposed converter shows low conduction loss due to low voltage stress of the secondary diodes, no dc magnetizing current for the transformer, and a lack of stored energy in the transformer. Moreover, since the primary MOSFETs are turned-on under zero voltage switching conditions and the secondary diodes are turned-off under zero current switching conditions, the proposed converter has minimized switching losses. In addition, the input filter can be minimized due to a continuous input current, and an output filter does not need an inductor in the proposed converter. Therefore, the proposed converter has the desired features, high efficiency and low profile, for a viable power supplies for digital car audio amplifiers. A 60-W industrial sample of the proposed converter has been implemented for digital car audio amplifiers with a measured efficiency of 88.3% at nominal input voltage. [ABSTRACT FROM AUTHOR]

A new cost-effective zero-voltage and zero-current switching (ZVZCS) current-fed energy-recovery display driver for a plasma display panel (PDP) is proposed. It features a simpler structure, less mass, and lower cost of production. Furthermore, since all power switches are turned on or off under zero-voltage or zero-current switching, it has several favorable advantages such as an improved electromagnetic interference (EMI), low switching losses, and reduced burden on the cooling system. Particularly, since the current source built in the inductor can compensate the large gas-discharge current, main inverter switches have the reduced current stress and turnon timing margin. Therefore, the undesirable voltage notch problem caused by the improperly controlled gate signal can be solved, which enables the panel to light at lower voltage such as 143 V compared with about 165 V of the prior circuit. To confirm the operation, validity, and features of the proposed circuit, experimental results from a prototype built with 6-in test PDP are presented. [ABSTRACT FROM AUTHOR]

A new cost effective zero-voltage (ZVS) and zero-current switching (ZCS) current-fed energy-recovery display driver for a plasma display panel (PDP) is proposed. It features a simpler structure, less mass, and lower cost of production. Furthermore, since all power switches are turned on or off under ZVS or ZCS, it has several favorable advantages such as an improved electromagnetic interference, low switching losses, and reduced burden on the cooling system. Particularly, since the current source built in the inductor can compensate the large gas-discharge current, main inverter switches have the reduced current stress and turn-on timing margin. Therefore, the undesirable voltage notch problem caused by the improperly controlled gate signal can be solved, which enables the panel to light at lower voltage such as 143 V compared with about 165 V of the prior circuit. To confirm the operation, validity, and features of the proposed circuit, experimental results from a prototype built with a 6-in test PDP are presented. [ABSTRACT FROM AUTHOR]

In this paper, a new zero-voltage-switching (ZVS) phase-shift full-bridge (PSFB) converter with low conduction losses is proposed. It is based on the PSFB converter with series-connected two transformers, which features wide ZVS ranges. By adding a capacitor, the proposed converter overcomes the disadvantage of the based converter, such as the high circulating energy. Furthermore, the turns ratio of the transformers can be increased as well. Therefore, high efficiency of the proposed converter can be achieved. Operational principles and experimental results for a 100-W (S V, 20 A) prototype are presented to validate the proposed converter. [ABSTRACT FROM AUTHOR]

A resonant energy-recovery circuit for a plasma display panel (PDP) employing a gas-discharge current compensation method is proposed. Its main concept is to make the resonant circuit biased by V8 and 0 V instead of V8 in charging and discharging the PDP, respectively. This operation helps the PDP to be fully charged and discharged and all main switches turned on under zero-voltage switching. Moreover, since the inductor current can compensate the large gas-discharge current, the current stresses on main power switches can be considerably reduced and all main switches have the turn-on timing margin, which ensures the no voltage drop across the PDP. Therefore, all these features could favorably provide a high energy-recovery capability, more accumulated wall charge, reduced sustaining voltage, and low electromagnetic interference. Therefore, the proposed circuit is expected to be well suited for a hang-on-the-wall PDP TV. [ABSTRACT FROM AUTHOR]

An analysis and design of single-stage, single-switch bi-flyback ac/dc converter is presented. The main flyback stage controls the output power from the link capacitor voltage with Discontinuous Conduction Mode (DCM) or Continuous Conduction Mode (CCM) operation, while an auxiliary flyback stage supplies the power to the output directly from ac line input with DCM operation. This scheme can effectively reduce the voltage stress on the link capacitor and can achieve the power factor correction (PFC) without a dead band at line zero-crossings, which reduces the harmonic distortion in ac line current. Theoretical analysis of the converter is presented and design guidelines to select circuit components are given. The experimental results on a 60 W (15 V, 4 A), 100 kHz ac/dc converter show that maximum link voltage and maximum efficiency are around 415 V and 82%, respectively. The power factor is above 0.96 under universal line input and load conditions. [ABSTRACT FROM AUTHOR]

Presents a design of a power-factor-correction converter based on a half-bridge topology suitable for low-power-level applications. Power factor type; Rate of harmonic distortion; Application of asymmetrical control and synchronous rectification; Efficiency of the converter; Rate of voltage stress on active components; Reduction of rectification losses; Switching frequency.

Proposes a push-pull type quantum series resonant rectifier for the power factor correction. Development of a samples data dynamic model for the rectifier; Analysis for the internal operational characteristics.

Focuses on the use of a quantum series resonant inverter as a direct-current motor drive. Sampled-data dynamic model; Optimal predictive resonant current control technique; Minimization of current error.

Presents a discrete time domain modeling for pulse-width modulated series resonant converters with a discontinuous current mode. Linearization of the nonlinear system; Verification of the signal's usefulness by dynamic simulation.

A highly efficient energy-recovery circuit (ERC) is proposed for plasma display panels (PDPs). This ERC employs an address voltage source used in an addressing period as the PDP is charged and discharged. As a result, the proposed circuit can reduce power consumption, switching loss, heat dissipation, and production cost. To verify the operation and features of the proposed circuit, experimental results with a 42-in standard-definition PDP are provided. [ABSTRACT FROM AUTHOR]

A full zero voltage switching (ZVS) range transient current buildup half-bridge converter is proposed. The proposed converter controls the secondary synchronous switches to build up the current for the ZVS operation. In addition, the blocking capacitor in the secondary side of the transformer is used to make the different current buildups and different ZVS operations with the load variation. Furthermore, it eliminates the dc offset of the magnelizing current. Therefore, the considerably effective ZVS characteristics can be ensured in the full-load ranges without any additional conduction losses. [ABSTRACT FROM AUTHOR]

A new input-voltage feedforward (IVFF) circuit for a voltage-doubler rectified asymmetrical half-bridge (VDRAHB) converter is proposed in this letter. The proposed circuit regulates output voltage not by reducing duty ratio but by increasing switching frequency as input voltage increases. Therefore, by employing the proposed IVFF circuit into the VDRAHB converter, the peak currents of the overall components can be greatly reduced, and also, efficiency can be improved at high input voltages. [ABSTRACT FROM AUTHOR]

A novel current-fed energy-recovery sustaining driver (CFERSD) for a plasma display panel (PDP) is proposed. It uses the current source to recover the energy stored in a PDP, which also provides zero-voltage switching (ZVS) of all main switches and the improved operational voltage margin. Furthermore, it features a lower conduction loss and faster transition time. It is well suited for wall-hanging color televisions (TVs). [ABSTRACT FROM AUTHOR]

A new current-fed energy-recovery circuit for a plasma display panel is proposed. All power switches are turned on with zero-voltage-switching, and its sustaining voltage is greatly reduced with the aid of the discharge current compensation. Furthermore, it features a simpler structure, less mass, lower current stress, and lower electromagnetic interface than prior circuits. It is well suited for wall-hanging colour TVs. [ABSTRACT FROM AUTHOR]

In many low-to-mid power applications, critical mode boost power factor corrector converters are widely used because of its low switching loss and simple control. However, near the zero crossing of the input line voltage, an input current distortion and a low power factor are caused by delayed switching period and negative input currents. Generally, an additional on-time method according to the input voltage is used to compensate the input current distortion. However, a detailed quantitative analysis for the exact additional on time has not been studied till now. In this paper, the explicit form of the optimized additional on time has been obtained using a quantitative analysis and the advantage of the digital control. From a state trajectory and "net input charge" analysis, it is shown that the optimized on time should be related to not only the input voltage, but also the output power. Also, in order to improve the efficiency in a high input and light load condition, circulating currents are reduced in the inevitable dead angle with a gate turning-off technique. By using digital control, the optimized additional on time and the gate turn-off technique have been implemented with the 90-230 Vrms input and 380 V/200 W output prototype. [ABSTRACT FROM AUTHOR]

Among the various cell balancing circuits for series-connected batteries, the bidirectional cell-to-cell balancing structure using two switches per cell shows good balancing ability. However, an increase in the number of switches leads to an increase in both cost and size. To reduce the number of switches, this paper proposes a new cell-to-cell balancing circuit with a center-cell concentration structure. The proposed circuit collects the charges of an overcharged cell into the center cell, and then the collected charges are redistributed to the other cells. The proposed circuit has a unidirectional balancing structure with single switch per cell. However, it can achieve competitive balancing ability when compared with the bidirectional structure. In this paper, the operational principles of the proposed circuit are analyzed, and a comparison between the conventional and proposed circuits is shown. To verify the validity of the proposed circuit, experiments with 15.5-Ah batteries are carried out, and the experimental results demonstrate the improved cell balancing ability although a single switch is used per cell. [ABSTRACT FROM AUTHOR]

This paper presents a new multioutput converter. It consists of a half-bridge inverter in primary side and a flyback rectifier that is integrated with an auxiliary buck converter in secondary side. The primary switches control the main output voltage and the secondary synchronous switches control the auxiliary output voltage. The main advantages of the proposed converter are that the transformer size can be reduced due to the lower magnetizing offset current, all the switches including synchronous ones can achieve the zero-voltage switching, and it has no cross regulation problems. The operational principle, analysis, and design considerations of the proposed converter are presented in this paper. The validity of this study is confirmed by the experimental results from dual-output (24 V/8 A and 12 V/4 A) prototype. [ABSTRACT FROM AUTHOR]

This paper proposes a pulse-width modulation three-level converter with reduced filter size using two transformers. The proposed converter has many advantages. All switches sustain only the half of the input voltage and since the secondary rectified voltage is a three-level waveform, the output filter inductor can be reduced. Also, because of the power sharing of transformer and reduced output inductor, high efficiency can be obtained. The operational principle, analysis, and design considerations of the proposed converter are presented in this paper. The validity of this study is confirmed by the experimental results from a prototype with 600 W, 500-600 V input, and 60 V output. [ABSTRACT FROM AUTHOR]

This paper proposes a new interleaved buck converter (IBC) having low switching losses and improved step-down conversion ratio, which is suitable for the applications where the input voltage is high and the operating duty is below 50%. It is similar to the conventional IBC, but two active switches are connected in series and a coupling capacitor is employed in the power path, such as Cuk, Sepic, and Zeta converters. The proposed IBC shows that since the voltage stress across all the active switches is half of the input voltage before turn-on or after turn-off when the operating duty is below 50%, the capacitive discharging and switching losses can be reduced considerably. This allows the proposed IBC to have higher efficiency and operate with higher switching frequency. In addition, the proposed IBC has a higher step-down conversion ratio and a smaller output current ripple compared with a conventional IBC. The features, operation principles, and relevant analysis results of the proposed IBC are presented in this paper. The validity of this study is confirmed by the experimental results of prototype converters with 150-200 V input, 24 V/10 A output. [ABSTRACT FROM AUTHOR]

The LLC resonant converter employing a center-tap rectifier can suffer from a high voltage oscillation across rectifier diodes owing to a leakage inductance of a transformer secondary. The amplitude of this voltage oscillation is varied according to design parameters, parasitic components, and operation regions, i.e., below-resonant region and above-resonant region. To reduce the diode voltage stress, this paper analyzes the voltage oscillation mechanism and presents the design consideration. [ABSTRACT FROM AUTHOR]

In low-to-medium power applications, an active-clamp forward (ACF) converter is popular for its simple structure and zero-voltage switching (ZVS) capability. However, the high voltage stress on switches can be a burden in high-input-voltage applications. To relieve this, a three-switch ACF (TS-ACF) converter, which employs two main switches for a forward converter and one auxiliary switch for an active-clamp circuit (ACC), is proposed in this paper. With a repositioned ACC, all the switches of TS-ACF converter have relatively low voltage stress compared to the conventional one. In addition, one of the main switches always ensures ZVS during the transformer reset. Consequently, the TS-ACF converter can be promising for high-input-voltage applications with high efficiency. [ABSTRACT FROM AUTHOR]

The flyback converter is one of the most attractive isolated converters in small power applications because of its simple structure. However, it suffers from a high device stress and a large transformer size. To relieve these drawbacks, a high-efficient pulsewidth modulation resonant single-switch isolated converter is proposed. The proposed converter derives the power using the resonance between transformer leakage inductor and secondary capacitor without a large filter inductor. Therefore, the switch turn-OFF loss and snubber loss are reduced by a sinusoidal-shaped current. Moreover, it has a reduced voltage stress on the secondary diodes without a dissipative snubber and a smaller transformer size. Therefore, it features a simple structure, low cost, and high efficiency. The operational principle and characteristics of the proposed converter are presented and verified experimentally with a 300~400 Vdc input, 70 Vdc/1.5 A output prototype converter. [ABSTRACT FROM AUTHOR]

A new boost half-bridge (BHB) converter is presented. It is composed of an additional diode and a coupled winding to the boost inductor of the BHB converter. Using the transferring of a boost inductor current to the coupled winding, the cancellation of zero-voltage-switching (ZVS) current, which always occurs in a conventional one, is prevented. Therefore, the ZVS operation is easily achieved by the leakage inductor current of the transformer. Furthermore, since the negatively built-up leakage inductor current of the boost winding helps the ZVS operation throughout a wide load range, the ZVS operation is always guaranteed. [ABSTRACT FROM AUTHOR]

A comparative study of a single sustaining driver (SSD) with single- and dual-energy recovery paths for plasma display panels (PDPs) is shown in this paper. The cost of PDPs is still very high and half of the cost includes the driving circuit. Therefore, it is important to have cost-effective driving waveform and the SSD to reduce the cost and size of the driving circuit. The SSD has fewer switching devices and reactive components and can be developed with single- and dual-path energy recovery circuits for charging and discharging PDPs. We shall evaluate the performance of these circuits in this paper. Since the dual-path energy recovery circuit has low power consumption, low surge current, and high performance. We shall verify these results using a 42-in high-definition panel. [ABSTRACT FROM AUTHOR]

A new dual sustaining driver using two different energy recovery circuits (ERCs) for large-sized plasma display panels (PDPs) is proposed. The proposed sustaining driver has two H-bridge inverters to be used in splitting a panel into two. Two ERCs are employed to compensate energy for charging or discharging the panel. When PDPs with the two divided panels are driven by the proposed driver, there are good uniformity in gas discharge and reduction of power consumption by the two different ERCs used in charging and discharging the panel. As results, the proposed sustaining driver has low conduction loss, diminished switching loss of all main power switches, and decrease of reactive power consumption for recovering energy. Moreover, production cost can be reduced because of the simplified ERC for discharging the panel and no additional driving circuits. To verify the operation of the proposed circuit, experimental results will be shown by using a 42-in panel. [ABSTRACT FROM AUTHOR]

A new double-ended type zero-voltage switching (ZVS) half-bridge zeta (HBZ) converter employing a double-ended rectifier (DER) is proposed. The proposed DER for the HBZ converter provides a bidirectional powering path in the rectifier. As a result, the improved voltage waveform of the rectifier reduces the output filter size and voltage stresses on rectifier components. Moreover, it offers a wide ZVS range. In addition, to minimize the secondary snubber loss, a simple lossless snubber is adopted. The operational principles and characteristics of the proposed converter are to be analyzed and verified experimentally. [ABSTRACT FROM AUTHOR]

A new phase-shifted full-bridge converter with a voltage-doubler-type rectifier for a high-efficiency power- sustaining module of a plasma display panel is proposed in this paper. The proposed converter employs a voltage-doubler rectifier without an output inductor. Since it does not have an output inductor, the voltage stresses of the rectifier diodes can be clamped at the output voltage level. Thus, since no dissipative resistor-capacitor snubber for rectifier diodes is needed, high-efficiency low-noise output voltage can be realized. Due to the elimination of the large output inductor, it features simpler structure, lower cost, smaller mass, and lighter weight. Furthermore, the proposed converter has wide zero-voltage-switching ranges of lagging leg switches with low current stresses of the primary power switches by using the magnetizing current. In addition, the resonance between the leak- age inductor of the transformer and the rectifier capacitors can reduce the current stresses of the rectifier diodes and conduction losses. In this paper, the operational principles, analysis, design considerations, and experimental results are presented. [ABSTRACT FROM AUTHOR]

A conventional phase-shift full-bridge (PSFB) converter has a serious voltage oscillation problem across the secondary rectifier diodes. To overcome this problem, a new voltage oscillation reduction technique (VORT), which effectively reduces the rectifier voltage oscillation by a simple nondissipative manner, is proposed. The concept of VORT is to utilize the operation of leading-leg transition, which does not cause severe rectifier voltage oscillation, to the lagging-leg transition. It is simply implemented by employing only a resonant capacitor in series with the transformer secondary and a small magnetizing inductance of the transformer without any lossy components. Moreover, the VORT can realize zero-voltage switching for all switches over a wide load range using the energy that is stored in the transformer magnetizing inductor and output filter inductor. The concept, operational principle, oscillation analysis, and design considerations of VORT are presented and verified experimentally. [ABSTRACT FROM AUTHOR]

In this paper, an active-clamp forward converter with transient current build-up zero-voltage switching (ZVS) technique is proposed. The proposed converter is suitable for the low-voltage and high-current applications. The structure of the proposed converter is the same as that of the conventional active-clamp forward converter. However, since it controls the secondary synchronous switch to build up the primary current during the very short period of time, the ZVS operation is easily achieved without any additional conduction losses of magnetizing current in the transformer and clamp circuit. Furthermore, there are no additional circuits required for the ZVS operation of power switches. Therefore, the proposed converter can achieve the high efficiency and low electromagnetic-interference noise resulting from the soft switching without any additional conduction losses and shows the high power density resulting from the high efficiency and no additional components added. The operational principle and design example are presented. Experimental results demonstrate that the proposed converter can achieve an excellent ZVS performance throughout all load conditions and a significant improvement in the efficiency for the 100-W (5 V, 20 A) prototype converter. [ABSTRACT FROM AUTHOR]

A new insulated-gate-bipolar-transistor (IGBT)-based cost-effective energy-recovery circuit (ERC) for a plasma display panel (PDP) is proposed. Since it is composed of two small resonant inductors and four power diodes instead of the conventional large auxiliary circuit, it features a simpler structure, less mass, fewer power devices, higher efficiency, and lower cost. Since all its power switches are turned off under the zero-current switching operation, IGBTs can be employed as power switches. Moreover, the very stable and uniform light emitted from a PDP proves the high quality of screen. Therefore, it is well suitable for the consumer-affordable hang-on-the-wall TVs which have the desirable features such as thinness, lightness, high efficiency, low price, etc. To confirm the validity of the proposed ERC, a comparative analysis and experimental results based on a whole ac PDP driver equipped with the proposed circuit for the 42-in PDP are presented. [ABSTRACT FROM AUTHOR]

A single-stage power factor correction ac/dc converter based on zero voltage switching (ZVS) full bridge topology with two series-connected transformers is proposed in this paper. The proposed converter offers a very wide ZVS range due to the configuration of two series-connected transformers. It features a high efficiency over wide load ranges. Furthermore, it shows the low voltage stress on a dc link capacitor. The proposed converter also gives the high power factor and low input current harmonics complied with IEC 61000-3-2 Class D requirements by integrating a boost stage operated in a discontinuous current mode. The ZVS conditions, large signal modeling, and design procedure are discussed in detail. Experimental results are presented to show the validity of the proposed converter. [ABSTRACT FROM AUTHOR]

A new active clamping zero-voltage switching (ZVS) pulse-width modulation (PWM) current-fed half-bridge converter (CFHB) is proposed in this paper. Its active clamping snubber (ACS) can not only absorb the voltage surge across the turned-off switch, but also achieve the ZVS of all power switches. Moreover, it can be applied to all current-fed power conversion topologies and its operation as well as structure is very simple. Since auxiliary switches in the snubber circuit are switched in a complementary way to main switches, an additional PWM IC is not necessary. In addition, it does not need any clamp winding and auxiliary circuit besides additional two power switches and one capacitor while the conventional current-fed half bridge converter has to be equipped with two clamp windings, two ZVS circuits, and two snubbers. Therefore, it can ensure the higher operating frequency, smaller-sized reactive components, lower cost of production, easier implementation, and higher efficiency. The operational principle, theoretical analysis, and design considerations are presented. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 200-W, 24-200 Vdc prototype are presented. [ABSTRACT FROM AUTHOR]

Presents a phase-shifted parallel-input/series-input dual converter. Features of the converter; Improvement in the efficiency of the converter; Suitability of the converter for high-power step-up applications.

A new high efficiency active clamp forward converter for the sustaining power module of a plasma display panel is proposed. It features zero voltage switching, a simpler structure, lower cost, less mass, and no effective duty toss. Furthermore, voltages across all rectifier diodes are clamped on the output voltage, which results in higher efficiency. [ABSTRACT FROM AUTHOR]

A new high-efficiency two-inductor boost converter is proposed in this letter. The proposed converter has topology variation characteristic by an additional single-pole double-throw relay. By operating a two-phase interleaved boost converter at ac low line input and single-boost converter with two series-connected inductors at ac high line input, the proposed converter efficiently utilizes two inductors and switching components. Therefore, the proposed converter can be optimally designed and its efficiency can be maximized at the respective ac input range. The proposed converter can be the most attractive solution for high-efficiency server power supply and other universal input power-factor-correction applications. [ABSTRACT FROM AUTHOR]

Recently, several researches have been progressed on the primary-side control (PSC) methods which decrease the size and cost of the control stage. However, most of the researches have been applied to the flyback converter, and they have some challenges in applying them to the half-bridge (HB) LLC converter due to the large voltage across the secondary leakage inductor of the transformer. In this letter, a new PSC method for the HB LLC converter is proposed to obtain accurate output voltage. In the proposed method, the output voltage is regulated by obtaining the voltage across the primary side of the transformer when the external resonant inductor voltage becomes 0 V. At this time, since the voltage across the transformer secondary leakage inductor is small, the proposed method can accurately regulate the output voltage. A 400 V input and 20 V/85 W output laboratory prototype is built and tested to verify the effectiveness of the proposed PSC method. [ABSTRACT FROM AUTHOR]

In phase-shifted full-bridge (PSFB) converter, using discontinuous conduction mode (DCM) is one of the most effective ways to improve efficiency in the light load condition. DCM of the PSFB converter allows getting reduced the duty ratio and zero voltage switching (ZVS) in the light load condition. Because of its simplicity, commercial IC adapted DCM by turning-off synchronous rectifiers (SRs). However, turning-off SRs causes large conduction losses in body diodes of SRs, and ZVS condition or optimized dead time are not defined yet. This letter proposes to use “AND-gated” control signals for SRs to reduce conduction losses in body diodes. Also, the ZVS condition is presented to design dead time easily. The feasibility of the proposed technique has been verified with 90-265 Vac input, 400 V link voltage, and 12V/750 W output server computer power supply system. [ABSTRACT FROM AUTHOR]