ZERO VOLTAGE SWITCHING HIGH STEP UP/DOWN BIDIRECTIONAL DC-DC CONVERTER UTILIZING THREE-WINDING COUPLED INDUCTORS

In this paper, a new zero voltage switching (ZVS) bidirectional dc-dc converter is proposed. The proposed converter has the capability of operating as a high step-up and high step-down converter because of having bidirectional power flow. The proposed converter is suitable for battery energy storage systems and hybrid electric vehicles. Moreover, in the proposed converter the current ripple at the low voltage and high voltage DC ports is cancelled by using an small inductance filter which causes increasing the lifetime of battery source. The proposed converter is analyzed, and the theoretical results are obtained. The obtained theoretical results are verified by using the experimental results.

THREE-PORT HIGH VOLTAGE CONVERSION RATIO DC-DC CONVERTER

In this paper, a new three-port DC-DC converter with high voltage conversion ratio is proposed. The proposed converter is useful for photovoltaic (PV) systems, which have a PV source integrated with an extra battery source to supply the output load. The voltage conversion ratio of the high dc voltage port over the low voltage dc port can be more increased by increasing the turns ratio of the coupled inductors for the whole range of duty cycles. The main advantage of the proposed converter comparing to other conventional three-port converters, is achieving higher voltage gain and higher ratio of voltage gain over components’ number. The proposed converter has also the leased normalized voltage stresses on switches for duty cycles higher than 0.3 among the conventional converters of the same type. Moreover, two output voltages of the proposed converter can be simultaneously regulated on different constant levels with a proper precision. In this study, the proposed converter is analyzed and the voltage conversion ratios, the inductors’ average currents, the voltage and current stress on switches are calculated theoretically. Finally, to verify the operation of the proposed converter, the experimental and simulation results of 20V/40V/400V prototype are extracted.

Control Method for LLC Converter Based on Power Factor with High Robustness Against Variation of Output Voltage and Load Impedance

The LLC converter is a very effective topology for miniaturization of power supplies. However, its application is currently limited. That is because of the problem of degraded system stability when the load condition changes. This paper proposed a control system that controls the output voltage by adjusting the power factor cosθ of the LLC converter to address this problem. As a result, simulations confirm that the proposed control method can significantly improve the frequency characteristics of the LLC converter and shows stable control characteristics regardless of the operating frequency. We also designed an experimental control circuit that can realize the proposed control.

Manipulation of Actual Demand in Electric Vehicles (MAD EV): A Cyber Security Perspective

This paper defines and analyses a specific cybersecurity risk for EVs, which we refer to as Manipulation of Actual Demand. This attack involves coordinated charging of a large number of EVs across multiple charging stations to disrupt the power grid. We provide a detailed analysis and quantification of the impact of this unique cyber-attack on the smart grid in terms of demand-side load. The findings of our analysis guide future considerations on cybersecurity risks of coordinated EV charging and their mitigation. We have made a comparison between Home EV chargers and Fast EV chargers via simulation. The results indicate the EV demand load threshold required to disrupt normal power grid operations

Impact of standardized methods applied for conducted EMI estimation on optimal volume of EMC filter in a single-leg inverter system

– In order to estimate the influence of standard measurement conditions on filter design, this paper discusses the impact of the absence of the line impedance stabilization network (LISN) on conducted emissions and consequently on the optimized volume of passive EMC filter in a single-leg inverter system fed by a DC source.
– addressing the problem of using the LISN in a more critical case (DC sources and DC grids) compared to state of art (AC grids)
-The enhanced two-probe HF impedance measurement method with a new setup allows accurate measuring in higher frequencies compared to state of art (until 50 MHz compared to 30 MHz from state of art)
– comparison of filter volume designed for each case and showing the increase in volume related to this problem.

A Novel Grid-friendly Vehicle-to-Grid Solution for Power Grid with Large-scale Renewable Fuel Vehicles

This paper presents a novel concept, named as smart mobile power bank, to implement grid-friendly vehicle-to-Grid technology. The concept and principle of mobile power bank is first developed, where multi-port DC/DC converter is developed to integrate hybrid energy storage system, photovoltaic panels, and various renewable fuel vehicles in a form of DC microgrid. Further, the operation and control strategy are developed to enable the proposed SMPB. The proposed solution is able to improve the security, flexibility and economy for power grid with high penetration of renewable fuel vehicles.

Development of Transformerless Switching Mode Power Supply System for PMU Devices

In this paper, we used transformerless voltage step-down operation to build an SMPS, which made our circuit smaller and lighter as well as we could get rid of the disadvantage of transformer (loss and heat issue) in power supply. Multiple outputs with positive and negative voltage from a single source were achieved according to the need of the PMU device. For reducing the circuit complexity we used a switching regulator IC to step down DC voltage. This work has developed, modeled, and implemented multiple novel approaches. The results are analyzed and documented for the research community.

Transformer Leakage Inductance Impact on Switching Behavior in a Full-Bridge Forward Converter

This paper presents how the leakage inductance influences the switching behavior of a hard-switched isolated full-bridge forward converter when it transitions from its ON to OFF state. Two sub-states are presented, and equations describing the current in the transformer primary winding is derived. It is presented that the dissipated turn-ON switching loss in the primary switches is highly influenced by an resonance frequency involving the leakage inductance. The calculations is verified by simulation and measurement, both performed when the converter is operated at 2:5kW output power.