Soft switched high gain trans inverse DC-DC converter based on three winding coupled inductor for renewable energy applications
Abstract
This article discusses non-isolated, trans-inverse, coupled inductor (CI)-based, soft-switching, high-gain DC-to-DC converter topology for renewable sources. The three-winding CI is utilized to achieve a high voltage gain with a reduced turns ratio. The energy associated with the magnetic components is recycled by the passive clamp circuit through diodes, and finally it pushes the output voltage to enhance the converter voltage gain. Besides, the soft switching performance of the clamping circuit occurs during the turn-off time of the controlled switch, thereby reducing the switching loss and the reverse recovery issue on the diodes. The proposed topology benefits from a reduced component count and enhances the output voltage gain. Furthermore, the topology performance analysis is carried out using PSIM simulation, and a 250W prototype using a dSPACE controller is analyzed with theoretical expressions.
Introduction
Electric vehicles play a major role in creating a pollution-free environment by integrating the electric vehicle charging system with any one of the renewable energy sources, making it more efficient with zero emissions. In electric vehicle charging systems integrated with renewable energy sources, the converters must manage continuous input current, handle a wide range of voltage gain with a lower duty cycle, and achieve a high voltage conversion ratio using the fewest number of components possible. This article focuses on designing the most appropriate converters to meet the above attributes.
In conventional DC-to-DC converters, such as boost and boost-derived non-isolated converters, do not achieve high gain at a large duty cycle. A larger duty cycle keeps the switch on for a long duration and increases the stress on the switch and other components, which leads to poor converter performances. The aforementioned shortcomings in conventional-type DC-to-DC converters led to the introduction of CI topology. CI used in and achieves high voltage gain while maintaining a lower duty cycle. The CI redirects its primary winding voltages to other energy storage elements, and finally, it pushes to the load side through one of the diodes. Use of CI simplifies the process of achieving high voltage gain in a DC-to-DC converter.
Voltage-boosting techniques such as the voltage multiplier (VM), switched capacitor (SC), switched inductor (SI) and cascaded technique (CT) are used by along with the coupled inductor. This cuts down on the number of semiconductor components, which makes the converter a little more efficient. Yet, these topologies suffer from voltage spikes in switches caused by leakage inductance, which lowers gain and efficiency. The high voltage spike causes the switch to fail. To solve the issue, use an active or passive clamp circuit across the switch. In the passive clamp circuits across the switches resolve these voltage spikes. As shown in the passive clamps circuits help recycle the energy from the CI to the clamping capacitor. This lowers the voltage spikes to below the output voltage and makes the converter more efficient. Even at low output voltage, the hard switching and reverse recovery issues in the DC-to-DC converter negatively impact the converter’s efficiency. Therefore, to address the major problem of switching loss, the converter circuits must operate under soft-switching conditions, either zero voltage switching (ZVS) or zero current switching (ZCS). In adding soft switching along with an active or passive clamp circuit improves the ability to reduce voltage spikes and lowers the problem of reverse recovery by slowing down the current that leaks out of the leakage inductance. From a high-gain perspective, the lack of an input inductor renders this converter topology unsuitable. The problem mentioned above is fixed in by adding an input inductor to the topology. This topology works under a ZVS turn-on to achieve high voltage gain with the same turn’s ratio at high operating frequency.
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