جستجوی مقالات مرتبط با کلیدواژه "کلیدزنی در جریان صفر" در نشریات گروه "برق"

Step-Up DC-DC Converters are widely used in electric vehicles, because the use of batteries and fuel cells increases the voltage level to drive the electric motor. One of the problems of step-up converters is the increase in volume and weight due to step-up transformers. So far, various methods, such as switched capacitor, coupled inductor and multiplier circuits, have been used to eliminate the transformer and reduce the volume and weight of the circuit. To further reduce the volume and weight of the circuit, it is necessary to increase the switching frequency, which is possible only by using the soft switching method. Using an auxiliary switch to create soft switching conditions is common in most methods, because not using an auxiliary switch imposes voltage and current stress on the circuit. In this article, a step-up converter with an auxiliary circuit of zero voltage transition (ZVT) is presented, which provides switching conditions at zero voltage to turn on the switch and switching at zero voltage to turn off the switch. The voltage stress of the converter is very low, and all the diodes are switched off at zero current, so they do not have reverse recovery problems. Also, in addition to absorbing the energy of the leakage inductor, the clamp capacitor helps to increase the gain of the converter. The provided converter is simulated in P-Spice software. To check the performance of the converter, a laboratory model with a power of 150 watts has been designed and tested.

The proposed converter is an interleaved ultra-large gain converter based on coupled-inductor (CI), built-in transformer (BIT) and switched capacitor (SC). The main novelty of the proposed converter is that the voltage gain can be achieved in proportionate to the multiplication of the turn ratios of the CIs and BIT that increase the voltage gain of the proposed converter. Also, through this topology, the voltage stresses across the power switches are effectively reduced and as a result MOSFETs with low ON-state resistances can be implemented that reduces the cost and conduction losses. Implementation of active clamp technique not only facilitates zero voltage switching (ZVS) turn-ON and turn-OFF for all switches, but also recycles the energy of the leakage inductances. Moreover, due to the presence of the leakage inductances, all of the diodes are turned OFF with zero current switching (ZCS) performance and the associated reverse recovery problem is solved, effectively. Through extensive comparison discussion, it is concluded that the proposed converter with low number of components outperforms previously presented ones in the terms of the voltage gain and voltage stresses across switches. Finally, the performance of the proposed converter is validated through developing a 100kHz 600W 22-380V prototype.

In this paper, an interleaved high step-up converter with a simple auxiliary circuit is presented. The proposed auxiliary circuit has the coupled inductor with the input inductors of the converter and provides zero voltage switching conditions for the main switches of the converter. On the other hand, auxiliary switches and diodes of auxiliary circuit operate under zero current condition and therefore do not impose significant losses on the converter. The auxiliary circuit is modular and can apply to more phases of the converter. Therefore, the converter can be easily designed for very high power applications. The proposed converter uses the cross-coupled inductors technique with series lift capacitors to increase the voltage gain and reduce the voltage stress on the main switches. Also, leakage inductance energy can be easily absorbed by the clamp capacitors and helps to increasing the voltage gain. The proposed high step-up converter has been analyzed in detail and a practical prototype has been implemented at 100W. The experimental results confirm the correctness of the operation of the circuit and the theoretical analysis.

An interleaved buck converter is presented in this paper that its operation is improved by providing soft switching condition. The proposed converter is included two similar buck converters and just one auxiliary circuit. The auxiliary circuit provides the soft switching condition for both main switches. In addition, soft switching condition is provided for auxiliary switch and diodes. The freewheeling diodes in output are replaced with synchronous switches to reduce the conduction losses in this converter. Simulation results of a 220 W – 100 kHz buck converter are presented to justify the validity of the theoretical analysis after analyzing the proposed converter and its operating modes. Bode diagram is also provided to compare transient responses of the proposed and regular buck converter. Moreover, efficiency curve of the proposed converter are presented for comparison with the same converter in hard switching condition that illustrate improvement of the converter efficiency.

In this paper an interleaved boost-flyback converter which was suitable for network connections of renewable energy sources is presented. Because in the solar system applications, level difference of the converter input and output voltage is high, boost converter cannot be used. Due to problems of the boost converter such as hard switching, voltage stress is equal to the output voltage. As regards in electronic converters, the power tends to increase the switching frequency to improve the converter response and increase its power density, hard switching caused to reduce converter efficiency. Also high voltage stresses of components have forced the designer to use semiconductor elements which can withstand in high voltage which will increase the losses in the converter and reduce its output. The proposed converter using LC resonant tank and auxiliary switches provides soft switching condition (ZCS) for the main converter. Interleaved techniques have used for reducing input current ripple and increase the size of the output capacitor and also boost-flyback converter have used to enhance converter gain and reduction of voltage stress of semiconductor components. The operating principle of the proposed converter is presented in this paper.

In this paper, a new soft switching high step up converter is introduced which its auxiliary circuit does not have any extra switch. Therefore, it no needs extra driver circuit and control circuit is simple. Also the energy in auxiliary circuit transfers to the output. The auxiliary circuit provides zero current condition for turns on and zero voltage condition for turns off instants of the switch. In addition all diodes turn off under ZCS condition and reveres recovery problem don’t exist in them. One of the advantages of the proposed converter is the reduction of the voltage stress across the switch due to its high voltage gain. Also, the auxiliary circuit has a low number of elements; therefore, high conduction losses do not impose on the converter. The coupling inductors in the auxiliary circuit have low values, so the volumes and parasitic magnitudes do not increase. To verify theoretical analysis a prototype of the proposed converter is implemented.

In this paper, a non-isolated three-port zero voltage switching bidirectional dc-dc converter without input current ripple. Some advantages of proposed converter are zero voltage switching of main switches, zero current switching of auxiliary switches. By using two active snubbers, it is possible to reduce circulating current and conduction losses. Free ripple condition of input currents is obtained by using coupled inductors in any stages that it reduces size of converter. The proposed converter can be used in boost, buck and buck-boost operation mods. If all of low voltage sources are equal or less than high voltage source, it is possible to increase the number of input sources to AWT IMAGEas a kind of AWT IMAGE-port converter. Finally, the zero voltage and zero current switching of switches and ripple free input currents of the proposed dc-dc converter is verified thruogh the simulation results in PSCAD/EMTDC software.