Design and Analysis of RCD Clamp Circuit in Flyback Converters
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This paper considers about ignored factors by past research work such as effects of forward and reverse recovery characteristics of the clamping diode and the leakage inductance Lsof the secondary side on RCD parameter design. The influence of the diode forward recovery on voltage spike of the power switch and reverse recovery on RCD clamp circuit power loss and parameter design is analyzed. Detailed analysis is given to reveal that the leakage inductance of the secondary increases the energy absorbed by the RCD clamp circuit as well as the primary leakage inductance. Meanwhile, a revised RCD parameter design method is proposed based on the existing design method, by taking consideration of forward recovery and reverse recovery characteristics of the clamping diode and the secondary leakage inductance Ls. Both simulation and experimental results validate the feasibility of the proposed design method.Keywords:
Leakage inductance
Clamper
Clamp
Leakage (economics)
Voltage spike
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A full-bridge dc-dc converter employing diode rectifier in the output experiences severe voltage overshoot and oscillation problem across the diode rectifier caused by the interaction between the junction capacitance of the rectifier diode and the leakage inductance of transformer. The pronounced reverse-recovery current of high power diodes enforces these issues significantly by increasing power loss and voltage overshoot. Conventional energy recovery clamping circuits suffer from high voltage overshoot if the input voltage of converter is wide. In this work, a novel energy recovery clamp circuit is proposed to overcome this problem. Performance of the proposed circuit is verified both theoretically and experimentally with a 70 kW dc-dc converter.
Clamper
Voltage spike
Peak inverse voltage
PWM rectifier
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In this paper, a novel simple high step-up converter using a coupled inductor and a charge pump capacitor is presented. Compared with the traditional boost converter and other converters with simple structures, the proposed converter can achieve higher voltage gain. The leakage inductance energy of the coupled inductor can be recycled without any clamp circuit. Moreover, the active switch is not floating; thus, no isolated driver is required. Finally, the operating principles and the analysis of the proposed converter and an experimental prototype are given to verify the effectiveness of the proposed converter.
Leakage inductance
Buck converter
Leakage (economics)
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This paper describes a boundary-mode forward-flyback converter (BMFFC) with zero-voltage switching that is able to process power efficiently. The theoretical analysis and operating principle of the BMFFC are presented in detail. A nondissipative LC snubber that recycles energy to the input source is employed in order to suppress the voltage spike caused by the leakage inductance of the transformer. The relatively large snubber capacitor also significantly reduces turn-off loss. Following a detailed design procedure, a 200 W prototype with a 25-50 V dc input and 230 V dc output was constructed and tested in order to evaluate the performance of the BMFFC.
Snubber
Leakage inductance
Voltage spike
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A full-bridge DC-DC converter employing a diode rectifier in the output experiences a severe voltage overshoot and oscillation problem across the diode rectifier caused by interaction between junction capacitance of the rectifier diode and leakage inductance of the transformer. The pronounced reverse-recovery current of high-power diodes significantly contributes to these issues by increasing power lossand voltage overshoot. Conventional energy recovery clamping circuits suffer from high voltage overshoot if the converter input voltage is wide. In this paper, a novel energy recovery clamp circuit is proposed to overcome this problem. The proposed circuit requires neither active switches nor lossy components. Therefore, the proposed circuit is very promising in high-voltage and high-power applications. Performance of the proposed circuit is verified both theoretically and experimentally with a 70-kW DC-DC converter.
Clamper
Voltage spike
Peak inverse voltage
Voltage multiplier
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Citations (56)
Introducing resonant inductance and clamping diodes into the full-bridge converter can eliminate the voltage oscillation across the rectifier diodes and increase the load range for zero-voltage-switching (ZVS) achievement. The resonant inductance is shorted and its current keeps constant when the clamping diode is conducting, and the clamping diode is hard turned-off, causing significant reverse recovery loss if the output filter inductance is relatively larger. This paper improves the full-bridge converter by introducing a reset winding in series with the resonant inductance to make the clamping diode current decay rapidly when it conducts. The reset winding not only reduces the conduction losses, but also makes the clamping diodes naturally turn-off and avoids the reverse recovery. The operation principle of the proposed converter is analyzed. The design of the turns ratio of transformer is discussed. A 1 kW prototype converter is built to verify the operation principle and the experimental results are also demonstrated.
Leakage inductance
Commutation
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This paper presents performance comparison between a two-switch and RCD clamp forward converters. The performance comparison is carried out through experimentation on the two prototype circuits, which have the same circuit specifications and similar component values. Aspects to be compared include voltage stress of switching components, output voltage regulation, transient response due to a step-load, and efficiency. Test results show that, while the two converters exhibit equal performance on output voltage regulation, the two-switch forward converter has a lower voltage stress on power switching devices, faster transient response, and higher efficiency than the RCD clamp forward converter.
Transient (computer programming)
Clamp
Voltage spike
Transient voltage suppressor
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A non-isolated zero-voltage transition interleaved high step-up converter with built-in transformer is proposed for high step-up and large current applications. The proposed converter consists of an interleaved structure, a built-in transformer and two sets of active clamp circuits. The built-in transformer can provide high voltage conversion ratio and increase the system efficiency without an extreme duty cycle compared with the conventional boost converter. The leakage inductance of the built-in transformer removes the output diode reverse-recovery problem, which results in low reverse-recovery losses. The active clamp scheme can suppress the surge voltage of the power MOSFETs and recycle the leakage energy, which is helpful to improve the circuit efficiency and reliability. Furthermore, zero-voltage switching soft switching performance is achieved for both the main and the clamp switches during the whole switching transition, which reduces the switching losses. The operation principle of the converter is analysed and verified. At last, some experimental results of a 1 kW prototype with 48 V input and 380 V output are given to demonstrate the effectiveness of the proposed converter.
Leakage inductance
Clamper
Duty cycle
Energy efficient transformer
Voltage spike
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A driver with high power factor, high efficiency and safety isolation are more attractive in the lighting application. Flyback is an ideal choice to be the power factor stage in LED driver. But one of the most difficulty in flyback topology is the energy stored in its leakage inductance. This part of the energy will introduce very high voltage spike on the main switch. A clamp circuit is needed.Passive clamp flyback converter is with few components and effectively clamping the voltage stress on transistor. But its switching frequency is limited by its switching loss. So the transformer volume in passive clamp flyback is very bulky. The aim of this project is to investigate high switching frequency Active Clamp Flyback converter with GaN transistor as power factor correction in lighting application.With the active clamp loop, the leakage inductance energy and snubber loss could be utilized properly to allow ZVS on switches under all line and load conditions and recycled to input source.So high switching frequency and high efficiency are both achievable. In this project,specific control method, dead time length and conduction mode are properly designed for active clamp flyback converter as PFC in lighting application.The implementation of closed control loop is not included.A 50W (75V) prototype of active clamp flyback front end converter operation around 1MHz with GaN transistor as Power Factor Correction stage in lighting application is developed to verify the analysis.
Flyback diode
Snubber
Leakage inductance
Voltage spike
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The charge storage diode (CSD) has useful characteristics of the long carrier lifetime and fast shut down of a recovery current at reverse recovery. When using the CSD snubber circuit to the DC-DC converter, during the storage time, the snubber energy is returned to the input by resonance phenomenon of the magnetizing inductance of the transformer and the snubber capacitor. Therefore the efficiency is improved. Magnetizing current is recycled when the CSD snubber is applied to the forward converter. And the core loss decreases because the maximum magnetic flux density reduces if the amplitude ^B of magnetic-flux density of the transformer is designed to same value to the conventional circuit. Also, because the designer can use bigger capacitor to the CSD snubber than conventional snubber, the effect that is equal to active clamp circuit is achieved. Then the switching device that with lower withstands voltage can be used. In this paper, characteristic of the CSD is introduced, and operation is described using the example that applied the CSD snubber to the forward converter. Then, the effectively is shown by the experiment with the forward converter, the flyback converter and the buck-boost push-pull converter.. The efficiency is 2-3% improved compared with the conventional circuit and the surge voltage of the switching device is clamped. However, it is often accompanied with a little difficult to perform the control operation like the active clamp circuit because use the storage time of the CSD. Therefore, it is important to design the CSD snubber circuit. This paper provides its design method, too.
Snubber
Voltage spike
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A new single-stage and single-switch isolated PFC converter with non-dissipative clamping is presented. The main advantage of the proposed circuit, which is derived from the flyback topology, is the exploitation of the transformer's leakage inductance in order to obtain a higher power factor. Additionally, it provides galvanic isolation as well as non-dissipative clamping of the overvoltages across the switch. The proposed circuit contains a small number of additional passive components without additional switches, leading to less complexity and higher efficiency. To verify the effectiveness of the proposed topology, simulation and experimental tests on a prototype were performed, showing both a high power factor and a proper clamping of the overvoltages without degradation of the efficiency.
Galvanic isolation
Leakage inductance
Single stage
Clamper
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Citations (7)