This research proposes a novel three phase isolated AC-AC bidirectional converter. Bulk filtering elements and a hard switched front end rectifier are the two significant components of a conventional AC-AC system, and they limit the switching frequency. However, the converter described in this study uses a higher switching frequency (100 kHz) to combine into a single-stage soft switched rectification, bypassing the bulk input filter for grid-connected systems like 50Hz and 60Hz systems. A higher bandwidth to reject higher order harmonics is produced by a high switching frequency, which also improves power density in the single stage conversion. It is capable of bidirectional integration of various frequency systems because of its symmetrical structure. Galvanic isolation is achieved by means of high frequency transformer. SVPWM is used to provide a new switching strategy that is best suited for bidirectional conversions. The proposed AC-AC MBTR converter’s initial simulation results are given.It is conceivable to consider this converter as a potential component for medium voltage solid-state transformers (SST) used in power distribution systems.

This paper presents an Multi-Input Multi-Output (MIMO) control strategy for a soft-switched AC-DC bidirectional power converter, optimally designed using an extended linear quadratic regulator (LQR) method. The proposed method is comprehensively compared with conventional approaches across three distinct scenarios: normal operation, harmonic mitigation, and grid imbalance conditions. Through detailed analysis and performance evaluation, our study demonstrates the superiority of the proposed control strategy in all three scenarios. Specifically, significant improvements are observed in harmonic mitigation and grid imbalance situations, where the proposed method exhibits exceptional effectiveness in reducing phase current total harmonic distortion (THD) and enhancing system robustness compared to conventional technique. These results emphasize the flexibility and effectiveness of the proposed control strategy in various operating conditions, indicating its capacity to improve the performance and reliability of AC-DC bidirectional converters in real-world applications.

Conventionally, an AC to DC isolated converter follows a two-stage design approach, wherein the first stage is a hard switched power factor correction (PFC) converter followed by a soft switched resonant converter stage. In existing single stage two level converter topologies, the two stages are merged resulting in 25% fewer devices. All the switches in these topologies are soft switched leading to a higher switching frequency of operation. However, the voltage stress on the devices are high. Also, this two level topology is not suitable for medium voltage AC applications. Moreover, this single stage converter is an unidirectional with power flow from AC to DC side. The existing multilevel topologies for medium voltage applications have a hard switched PFC stage followed by a soft switched resonant stage. In order to overcome aforementioned shortcomings, this paper presents a novel isolated bidirectional multilevel bridge tapped resonant (MBTR) AC to DC converter. It is based on a multilevel diode clamped topology where PFC stage and resonant stage are merged into single stage with 25% reduction in device count. The switches in the proposed converter are soft switched facilitating higher switching frequency of operation. A new modulation technique is proposed for generating gating pulses for the switches. The preliminary simulation results of the proposed MBTR converter are provided.

An emerging scenario of using Electric Vehicles to provide reactive power support arises as the population of Electric Vehicles (EVs) increases significantly. In view of this emerging scenario, a new application of Particle Swarm Optimization is proposed in this paper, which is adopting Particle Swarm Optimization (PSO) in Vehicle-to-Grid (V2G) based reactive power dispatch. Rather than utilizing reactive power support from central generators, the proposed method aims at increasing reactive power support from EVs, which are distributed. Case study on a modified IEEE 9-bus system is done and results show that the proposed method can bring convincing benefits on voltage stability and power loss in the overall power system.

This paper describes a non-isolated matrix based buck-boost converter applicable for the aircraft systems. A matrix based topology is used which converters the three phase low frequency input ac voltages into an intermediate high frequency ac voltage. The high frequency ac voltage is rectified using Current Doubler Rectifier (CDR). The output voltage of the CDR circuit is further stepped-up by using a dc-dc boost converter to obtain the desired output voltage. Both, the conventional three phase buck and the three phase boost converter have limitations over the maximum and minimum voltage gain, respectively. The proposed buck-boost converter overcomes such limitations and provides output dc voltage with reduced current distortion and improved power conversion efficiency. Moreover, the novelty of the paper lies in integrating the output filter inductor of the matrix topology with the input inductor of the boost stage resulting in complete elimination of the intermediate filter capacitor and the input boost inductor. The topology and the principles of the operation of the proposed converter are explained in details. Further, the analysis of the converter is carried out. Moreover, the performance of the proposed converter is compared with the boost-buck and conventional buck-boost power converters. The proposed converter is simulated in MATLAB 2015b and results are presented to validate the performance of the converter.

This paper presents a novel switching scheme named as Switched Rectifier Inverter (SRI) modulation scheme for three phase to single phase (3×1) Matrix converter based isolated AC-DC converter. The proposed SRI modulation scheme incorporates symmetrical Space Vector Modulation (SVM) with inverter logic for switching the twelve switches of Matrix based AC-DC converter. The operation of proposed SRI modulation scheme is discussed and analyzed in details. The significant contribution of proposed modulation scheme in terms of power density, efficiency and power quality is discussed. Finally, the converter is simulated with proposed modulation scheme on MATLAB R2011b and PLECS 3.5 based software platform for an isolated three phase AC-DC converter of input 120 V(rms), 400 Hz AC (aircraft input supply) to output 400 V DC at 8 kW power.

AC/DC converters used in electric vehicles generally consist of two stages: an input power factor correction (PFC) boost AC/DC stage that converts input AC voltage to an intermediate DC voltage and reduces input current harmonics injected to the grid, and a DC/DC converter that provides high-frequency galvanic isolation. Since there is a low-frequency ripple (second harmonic of the input ac line frequency) in the output voltage of the PFC AC/DC boost converter, the voltage loop in the conventional control system typically has a very low bandwidth to avoid distorting the input current waveform. This causes the conventional PFC controller to have slow dynamics against load variations. This paper presents a new control approach that regulates the input power of the converter instead of the output voltage by using an optimal nonlinear control approach based on the Control-Lyapunov Function (CFL). In this paper, it is shown that the proposed controller is able to eliminate the low bandwidth voltage control loop in the conventional PFC controller, thus allowing the front-end AC/DC boost PFC converter to operate with faster dynamic response than with the conventional controller approach. Experimental results from a 3 kW AC/DC converter are presented in the paper to validate the proposed control method and its superior performance.