LLC resonant converters, generally adopting frequency modulation control, can hardly achieve high efficiency under both heavy and light load conditions. Especially under light load conditions, the high-switching frequency seriously degrades converter's efficiency. This study propose a new pulse-width modulation (PWM) control strategy for LLC resonant converters under light load applications on the premise of no change in the main circuit structure. The voltage gain of the converter is regulated by varying duty ratio instead of increasing switching frequency and therefore zero-current switching for rectifier diodes can be realised under light load conditions. With the proposed PWM control strategy, the gain is not affected by the load variations and an optimal design of the magnetic components is possible, therefore the efficiency is further improved by reducing both the switching losses and the losses in magnetic components. Experimental results demonstrate the effectiveness of the proposed PWM strategy by increasing the efficiency of LCC resonant converter, especially under light load conditions.
High gain step up DC-DC boost converters are considered as an important part in different renewable energy sources (RES). In this paper a modified high gain setup up DC-DC quadratic boost converter is introduced. The proposed topology not only enhance the high voltage gain but also decrease the voltage stress across the semiconductor switches as well overall converter loses. To validate the proposed method efficacy, experiment performed in laboratory where 5 VDC are given as an input and at output we attained 62.5 volts with output power of 19.5 watts. The maximum efficiency of proposed converter at input power of 20 W is 95.39% and at 3.7 W it is 83.52%. Whereas, the conventional converter efficiency at the same input power is 93.89% and 82.96% respectively.
Abstract. In this paper a DC-DC boost converter with voltage extension cell is introduced to reduce losses and voltage stresses on circuit components. From theoretical analysis it has been analyzed that DC-DC boost converter coupled with extension cell enhances its voltage gain, which improve the life time of circuit components. Further to validate the proposed method, simulation has been performed in Matlab Simulink Software to compare the output voltage of boost converter with and without proposed method, result shows that the output voltage of proposed method is 35V as compare to simple boost converter 25 V. Voltage stress in case of basic boost converter is 25V while for boost converter with extension cell is 10 V.
High step-up dc-dc converter is an essential part in several renewable energy systems. In this paper, a new topology of step-up dc-dc converter based on interleaved structure is proposed. The proposed converter uses three energy storing capacitors to achieve a high voltage gain. Besides the high voltage gain feature, the proposed converter also reduces the voltage stress across the semiconductor switches. This helps in using low rating switching devices which can reduce the overall size and cost of the converter. The operating principle of the proposed converter is discussed in detail and its principle waveforms are analyzed. An experiment is carried out on a 20 V input, 130 V output, and 21 W power prototype of the proposed converter in the laboratory to verify the performance of the proposed converter. An efficiency of 91.3% is achieved at the rated load.
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