Lossless Snubber Circuit Research Articles

A Method for CM EMI Suppression on PFC Converter Using Lossless Snubber with Chaotic Spread Spectrum

This paper proposes an improved common mode (CM) electromagnetic interference (EMI) suppression method in switching power supplies. The lossless snubber circuit can reduce du/dt and EMI in the high-frequency band. Nevertheless, it has a weak EMI suppression effect on the low-frequency band. A method combining the chaotic spread spectrum and the lossless snubber (CSS–LS) is proposed to improve the EMI suppression effect of the lossless snubber. It is an effective means to suppress CM EMI further. The paper used a Boost PFC converter as the object of analysis to study the CM EMI suppression effect of CSS–LS. Firstly, a CM EMI-equivalent model of the lossless snubber PFC converter was established. Then, the power spectral density function under chaotic spread-spectrum modulation was derived. The simulation analysis was performed. Finally, an experimental prototype was built, and relevant EMI tests were carried out. The experimental results show that CSS–LS can reduce CM EMI by 4~20 dBµV with little impact on converter stability. Fewer extra costs are needed for this optimization method, which is suitable for high-power-density power electronic devices.

A new lossless snubber for DC-DC converters with energy transfer capability

In this paper, a new passive lossless snubber circuit with energy transfer capability is proposed. The proposed lossless snubber circuit provides Zero-Current Switching (ZCS) condition for turn-on instants and Zero-Voltage Switching (ZVS) condition for turn-off instants. In addition, its diodes operate under soft switching condition. Therefore, no significant switching losses occur in the converter. Since the energy of the snubber circuit is transferred to the output, there are no significant conduction losses. The proposed snubber circuit can be applied on isolated and non-isolated converters. To verify the operation of the snubber circuit, a boost converter using the proposed snubber is implemented at 70W. Also, the measured conducted Efficiency Electromagnetic Interference (EMI) of the proposed boost converter and conventional ones are presented which show the effects of proposed snubber on EMI reduction. The experimental results confirm the presented theoretical analysis.

A High Step-Down Buck Converter With Self-Driven Synchronous Rectifier

In this article, a new single-switch buck converter (without considering the synchronous rectifier) with extended duty cycle and continuous output current is proposed. The presented converter employs a self-driven synchronous rectifier with gate energy recovery, which leads to efficiency improvement and simplicity of the converter and the gate drive circuit. The extended duty cycle results in lower current stress of the high-side MOSFET and reduced voltage stress across the synchronous rectifier. Furthermore, the reverse recovery losses of synchronous rectifier are dramatically decreased due to the applied coupled inductors. The introduced converter also provides shoot-through protection and load protection when the high-side MOSFET remains on . In order to clamp the drain–source voltage spikes of the main switch and recover the leakage inductance energy, a lossless snubber circuit is added, which reduces the turn- off drain–source voltage and consequently decreases the turn- off switching losses of the main MOSFET . Moreover, the main switch turns on under zero current switching (ZCS), which results in efficiency improvement. A 150-W prototype of the proposed converter is implemented to verify the theoretical analysis and confirm its efficiency improvement and advantages.

Isolated SEPIC DC–DC Converter With Ripple-Free Input Current and Lossless Snubber

This paper proposes an isolated single-ended primary-inductor converter (SEPIC) dc–dc converter with ripple-free input current and lossless snubber. The proposed converter is based on a conventional isolated SEPIC converter to enable electrical isolation and high voltage gain using a coupled inductor. The input current ripple is significantly reduced by utilizing an auxiliary circuit that also functions as a lossless snubber circuit with an additional diode. Moreover, the maximum switch voltage stress is clamped to a low voltage by the snubber circuit. Therefore, a low voltage rating mosfet that has low $R_{{\rm{DS(on)}}}$ can be utilized as a main switch device. Hence, the total power efficiency is improved. Experimental results from a 100 W prototype, which are presented to verify the theoretic analysis and performance of the proposed converter.

HF Transformer Based Grid-Connected Inverter Topology for Photovoltaic Systems

ABSTRACTInverters are required to convert the dc power from photovoltaic panels to ac. In grid connected inverters, the ac output is directly fed into the electric grid. In this paper, a high-frequency transformer based inverter topology is presented. This leads to a very compact inverter. The modulation of this inverter with a lossless snubber circuit is proposed. Proposed modulation eliminates the over-voltage spikes due to transformer leakage inductance. Commutation of the leakage inductance energy with this modulation is also discussed. The performance of the inverter with the proposed modulation is validated using simulation and experimental results.

New Soft Switching Circuit using Lossless Snubber Circuit for Zero-Voltage-Transition Converter

A new soft switching circuit system with a lossless snubber circuit as an auxiliary circuit in the soft switching circuit is proposed in this letter. Soft switching operation is achieved for the main switch and the auxiliary switch. Moreover, zero current switching operation in the turn-off of the main switch is also realizable in the proposed circuit by using the charging voltage of the auxiliary capacitor in the lossless snubber circuit.

A Design of Cascaded Multilevel Inverter Snubber Circuit

The high frequency induction heating power supply has received increasing attention from researchers, multilevel converter is a high voltage large power application areas of research focus and core, it solves the problem of the multilevel inverter output voltage waveform adjustment, avoids the problem of two times reversing that the load voltage in the commutation during the dead period occurred. An effective way to improve efficiency is to keep the power device of low voltage stress and less switching loss. A passive lossless snubber circuit is designed for inhibiting the reverse recovery current of diode and improving the turn-on condition of powers switch. The operation process of snubber circuit is analyzed and the parameter design method is given. The results of simulation have verified the validity of design methods and the conclusions given by theoretically analyzing in this paper.

PWM-controlled soft-switching SEPP high-frequency inverter for induction-heating applications

A novel single-ended push pull (SEPP) soft-switching high-frequency inverter for induction-heating applications with a continuous output power regulation scheme at a fixed frequency incorporating a novel lossless snubber circuit is presented. Conventional SEPP high-frequency inverters have been finding their home-electronic applications owing to their simplified circuit constitutions. However, their soft-switching operations were restricted in a relatively narrow output power range when they were controlled by a PWM technique. The proposed high-frequency inverter topology is based on the conventional SEPP high-frequency inverter together with a novel lossless snubber circuit operated at an auxiliary resonant frequency so that it can be operated under soft-switching as well as PWM regulations. Hence, the soft-switching operation range of the proposed inverter can be widened considering accompanied by a high efficiency compared with the conventional SEPP inverter. Uses can include a home-cooking application with a high thermal efficiency and high safety at a fixed frequency of 20 kHz. The operating principle, is described and the results of computer-aided simulation analysis of the circuit operation and evaluation of the performance of the proposed inverter are given, which show its high utility.

Utility-interactive photovoltaic power conditioning systems with forward converter for domestic applications

Various utility-interactive photovoltaic power conditioning systems have been reported. In general, it could be said that such photovoltaic power conditioning systems have been approaching the ideal, i.e. high efficiency, high performance etc. However, the system cost including that for power converters and solar cells still prevents widespread application. A simple utility-interactive photovoltaic power conditioning system with a forward converter and an innovative lossless snubber circuit are proposed. They are easy to utilise and complement each other. The system operation is confirmed by simulation analysis and experiment.