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A zero-voltage and zero-current switching full bridge converter with series resonance tank is presented in this study. This converter is based on standard full bridge topology and a series capacitor is added in the primary side to reset the leakage inductance current without any additional auxiliary circuit. Leakage inductance of the transformer is used as the resonance inductance. Using series resonance tank and applying control pulses with fix frequency, zero-voltage switching for leading leg and zero-current switching for lagging leg is achieved. The output power is controlled using phase shift technique. In the proposed converter, soft-switching condition is attained for wide range of load variation. Due to its high performance and minimum additional components with respect to regular converter, this converter can be applied for medium to high-power applications. Topology and operating modes are discussed and the validity of theoretical analysis is verified by prototype experimental results.

A new interleaved high step‐up DC–DC converter is presented in this paper, providing very high voltage conversion, significantly lowering the voltage stress across semiconductor components, and minimizing conduction losses. In this topology, an active snubber circuit guarantees zero‐voltage switching (ZVS) of the main switches over a wide load range, while the auxiliary switch achieves complete zero‐current switching (ZCS) operation without contributing to additional power losses in the converter. Since the duty cycle of the auxiliary switch is small, the auxiliary circuit remains active in the converter for a short duration. The use of fixed‐frequency PWM control enables an optimized design of the magnetic components while keeping the control implementation relatively simple. In addition, because the input and output terminals share a common ground, the control circuit does not require input‐side isolation, thereby further simplifying the overall system design. The theoretical analysis is validated by a 250 W prototype with 20 V input to 600 V output voltage with a 100 kHz switching frequency. The proposed topology provides high voltage gain and enhanced efficiency at low duty cycles, thereby reducing conduction losses in the switches. Its interleaved structure ensures current sharing, while the switches experience both low voltage and low current stress, further decreasing conduction losses. In addition, full soft‐switching operation is achieved for all switches, which eliminates capacitive turn‐on and minimizes switching losses.

This paper presents a high-frequency pulse-density-modulated (PDM) soft-switching series load resonant inverter for use in induction heating (IH) fixed roller applications, which is used in copy and printing machines. The proposed simple high-frequency resonant inverter uses an asymmetrical pulse pattern PDM control scheme to achieve complete zero-current soft-switching commutations over a wide output range of input power regulation. Additionally, when the printer toner requires operation in very light load conditions, this causes difficulty in achieving zero-voltage or zero-current soft-switching operations in the IH high-frequency resonant inverters with pulse frequency modulation or pulse width modulation control schemes. The proposed resonant inverter demonstrates the capability to accomplish highly efficient power conversions. In this work, a fixed roller for printing machines is developed for doing experiments to verify the efficiency of the proposed circuit topology and its PDM control schemes. The inverter’s steady-state and transient operating principles are analyzed based on the proposed control strategy at a high-frequency PDM. Operating conditions such as power loss analysis, power conversion efficiency and temperature rise characteristics of the proposed inverter are presented and analyzed through experimental results. Finally, from a practical viewpoint, a comparative study of a conventional halogen lamp heater and the proposed IH fixed roller is deliberated.

In this study, a new family of pulse width modulation DC–DC converters is introduced. The proposed converters have one switch that turns on at zero current switching condition and turns off at zero voltage switching condition. The proposed auxiliary circuit can be used instead of converter switch in any non-isolated and isolated DC–DC converter. The buck converter from this converter family is analysed and its operating modes are discussed. The design considerations are presented and a prototype is realised. The experimental results confirm the validity of theoretical analysis.

A novel interleaved boost dc/dc converter with zero-current-switching pulse-width-modulation (ZCS-PWM) characteristic using a simple ZCS-PWM auxiliary circuit is presented in this paper. The proposed converter combines the conventional PWM technique and ZCS technique to promote the circuit performance. The proposed converter uses dual boost converters which are operated at interleaved mode to increase the output power level. Thus, the proposed converter does not only decreases the current stress on main circuit devices but reduces the input ripple current and output capacitor size. Because the proposed converter establishes a common ZCS-PWM auxiliary circuit on used dual boost converters, it can greatly reduce the size and cost. And, it can provide the ZCS characteristic on main switches and auxiliary switches with a wide range of load to improve the problem of switching losses and EMI. Thus, its topology is simple and compact. Besides operating at constant frequency and reducing commutation losses, the proposed converter has no additional current stress and conduction loss in the main switch compared with the conventional interleaved boost dc/dc converter. The principle of operation, theoretical analysis and experimental results of the proposed boost converter, rated 1 kW and operating at 40 kHz, are provided in this paper to verify the performance of this new family of converters.

In this study, an improved two-switch zero-current zero-voltage switching pulse-width modulation (ZCZVS-PWM) forward converter, which employs a simple resonant lossless snubber circuit, is introduced. A simple resonant snubber circuit consists of a capacitor, an inductor and two diodes. In proposed converter, switch Q1 operates under exactly zero-current switching at turn-on, and exactly zero-voltage switching (ZVS) at turn-off, and switch Q2 operates under exactly ZCZVS at turn-on, and ZVS at turn-off, and the all-passive semiconductor devices operate under soft-switching at turn-on and turn-off. The proposed converter has no current and voltage spikes in the switches in comparison with the hard-switching forward converter counterpart and is suitable for high switching frequency and high-power operation. The proposed converter is analysed and various operating modes of the improved two-switch ZCZVS-PWM forward converter are discussed. Analysis and design considerations are presented and the prototype experimental results of a 160 W (32 V/5 A) proposed converter operating at 300 kHz switching frequency, confirm the validity of theoretical analysis.

In this study, a single-stage half-bridge flyback converter using a synchronous rectifier (SR) is proposed to achieve unity power factor and higher efficiency. The proposed power factor correction can achieve almost a unity power factor and low input ripple current. The asymmetrical pulse-width modulation (APWM) half-bridge flyback converter operates under zero-voltage switching to reduce switching losses. The conduction loss of the system can be reduced by replacing the diode rectifier with an SR using a low on-resistance metal oxide semiconductor field effect transistor and the SR switch operates under zero-current switching. Detailed analysis is presented on the proposed converter. Experimental results for a 24 V/200 W converter at a constant switching frequency of 100 kHz were obtained to prove the analysis.

DC–DC converters are needed to supply power with high efficiency in various applications in industry. However, the conventional DC–DC converters cannot achieve higher efficiency mostly owing to the switching and conduction losses. On the basis of existing topologies, in this study a novel ZVT auxiliary circuit with dual resonant tank for the DC–DC converters with synchronous rectification (SR) is proposed. The proposed ZVT auxiliary circuit aims at reducing losses of conventional DC–DC converters by using zero-voltage-switching, zero-current-switching and SR with reduced reverse recovery time of junction diodes. To verify the proposed circuit, a Buck converter integrated with the proposed dual resonant tank is implemented in this study. The simulated and experimental results obtained have demonstrated that the proposed dual resonant tank can be practically implemented in conventional DC–DC converters to provide better performance as compared with existing topologies.

An interleaved series resonant converter with fixed frequency pulse-width modulation (PWM) is presented to achieve load current sharing, ripple current cancelation, zero-voltage switching (ZVS) for power switches and zero-current switching (ZCS) for rectifier diodes. Two three-level DC converters with clamped diodes and flying capacitor are adopted to share load current. The voltage stress of power switches is clamped at one-half of DC bus voltage. The interleaved PWM scheme is used to control two converters in order to reduce the output current ripple and size of output capacitor. The series resonant tank in three-level PWM converter is adopted to realise ZVS turn-on for all power switches andZCS for rectifier diodes. Thus, the switching losses of active switches are reduced and the reverse recovery losses of rectifier diodes are eliminated. The fixed frequency PWM operation is adopted to regulate output voltage, so that the drawback of a wide range of switching frequency in the conventional series resonant converters is overcome. Finally, experiments based on a scale-down prototype are provided to verify the effectiveness of the proposed converter.

A novel Pulse-Width-Modulation (PWM) quasi-resonant active-clamp phase-shifted full-bridge converter is presented and analyzed in this paper. In the proposed topology, an active-clamp switch and a clamp capacitor that resonates with the leakage inductance of transformer are employed at the secondary side. The active-clamp circuit helps all of the primary switches in achieving both zero-voltage switching (ZVS) turn-on and nearly zero-current switching (ZCS) turn-off over the entire load range, and resets the primary current during the freewheeling interval. The operation of the active-clamp circuit eliminates voltage ringing across the rectifier. In addition, the secondary diodes can achieve ZCS turn-off, which removes the reverse recovery problem of diodes, and the active-clamp switch can achieve ZCS turn-on. A 3.5-kW prototype was built to verify the performance of the proposed converter. A maximum efficiency of 97.6% was achieved under a 2-kW load, and an efficiency of more than 96% was achieved even under a light load.