Non-isolated Converter Topology Research Articles

Finite control set model predictive control of three-port converter for interfacing a PV–battery energy storage system to a three-phase stand-alone AC system

Abstract This paper proposes a multiport bidirectional non-isolated converter topology that provides advantages in terms of simultaneous multiple operations, single-stage conversion, high power density and reduced power losses due to the lower number of switches. The proposed multiport converter uses a centralized non-linear controller known as a finite control set model predictive controller to manage the flow of power between different ports. It deals with the parallel operation of photovoltaic and battery energy storage systems for stand-alone alternating current (AC) systems. The converter connects the lower voltage battery to the photovoltaic port using a bidirectional buck/boost converter and the photovoltaic port is linked to the stand-alone AC load through a three-phase full-bridge inverter. Each leg of the three-phase converter will act as a bidirectional direct current (DC)/DC converter as well as an inverter simultaneously. Only six switches manage the power transfer between all the connected ports of photovoltaic–battery energy storage system linked to the stand-alone AC load. The proposed multiport converter is mathematically modelled and controlled by a finite control set model predictive controller. The system is validated in simulation (1-kW rating) and experimental environment (200-W rating). The hardware prototype is developed in the laboratory and the controller is implemented on the field-programmable gate array board. Two independent case studies are carried out to validate the efficacy of the system. The first scenario is for a change in solar irradiance, while the second scenario is for a change in the output load.

Bridgeless isolated sepic PFC for EV battery charging using ANN controller

The power quality of an Electric Vehicle (EV) battery charger is improved in this work using a bridgeless isolated single ended primary inductance converter (SEPIC). Owing to the excessive amount of conduction losses associated with the conventional Diode Bridge Rectifier (DBR) based Power Factor Correction (PFC) circuit; a Bridgeless circuit model is preferred in this work. The safe functioning of the PFC circuit is further ensured by selecting an isolated topology over a non-isolated converter topology. With the use of an artificial neural network (ANN) controller, the converter's operation is improved in terms of rising time, overshoot, steady state error and settling time. Distortions in the input current are curtailed with the aid of Hysteresis Current Controller (HCC). The entire work of the proposed converter in terms of design equations and several operating modes is detailed elaborately. The input current displays functioning with a unity power factor for the full charging period. The proposed Bridgeless Isolated SEPIC PFC's efficacy in improving the power quality of the EV charger system is determined using simulation results from MATLAB and hardware implementation utilising a DSP30F411 controller.

An Analysis of Non-Isolated DC-DC Converter Topologies with Energy Transfer Media

As miniaturized mobile devices with various functionalities are highly desired, the current requirement for loading blocks is gradually increasing. Accordingly, the efficiency of the power converter that supports the current to the loading bocks is a critical specification to prolong the battery time. Unfortunately, when using a small inductor for the miniaturization of mobile devices, the efficiency of the power converter is limited due to a large parasitic DC resistance (RDCR) of the inductor. To achieve high power efficiency, this paper proposes an energy transfer media (ETM) that can make a switched inductor capacitor (SIC) converter easier to design, maintaining the advantages of both a conventional switched capacitor (SC) converter and a switched inductive (SI) converter. This paper shows various examples of SIC converters as buck, boost, and buck-boost topologies by simply cascading the ETM with conventional non-isolated converter topologies without requiring a sophisticated controller. The topologies with the ETM offer a major advantage compared to the conventional topologies by reducing the inductor current, resulting in low conduction loss dissipated at RDCR. Additionally, the proposed topologies have a secondary benefit of a small output voltage ripple owing to the continuous current delivered to the load. Extensions to a multi-phase converter and single-inductor multiple-output converter are also discussed. Furthermore, a detailed theoretical analysis of the total conduction loss and the inductor current reduction is presented. Finally, the proposed topologies were simulated in PSIM, and the simulation results are discussed and compared with conventional non-isolated converter topologies.

High-Efficiency Nonisolated Converter With Very High Step-Down Conversion Ratio

This paper introduces a new nonisolated converter topology with very high step-down conversion ratio and high efficiency for high current low voltage point-of-load voltage regulator modules. Compared to a conventional two-phase buck converter, the new converter triples the effective duty-ratio and lowers the voltage stress of the transistors, significantly reducing the overall volume of the converter while maintaining high efficiency. The new converter is capable of delivering high current to the output by two interleaved phases and further features an inherent current sharing to balance the load between the phases. The use of lower voltage stress transistors allows operation at high switching frequencies that translates into fast dynamic response to load perturbations. The operation of the topology is verified on a 30 W, 48 V-to-1 V prototype, demonstrating peak efficiency of 91.5% and above 88% for most of the load range.