This paper presents a review of isolated matrix inverters. The study contributes to creating a point of reference for a comprehensive classification of existing solutions. Over 30 topologies were reviewed, and the main advantages and disadvantages discussed. Applications of isolated matrix inverters are summarized in a tabular form to demonstrate their flexibility for different power and voltage levels achieved due to the presence of a transformer. These inverters have been proposed for the uninterruptible power supplies, high and low-voltage/power photovoltaic systems, low-power fuel cell, different low- and high-voltage battery and/or electric vehicle chargers, audio amplifiers. The fully controlled switches on both terminals of these converters typically can provide the bidirectional power transfer capability, which is also addressed for most of the topologies, but requires some modification in their modulation strategy. Average efficiency of today’s isolated matrix inverters is comparable with the two-stage power converters; however, they can provide higher reliability and lower cost.

https://www.mdpi.com/1996-1073/13/9/2394/pdf

Review of Isolated Matrix Inverters: Topologies, Modulation Methods and Applications

Quite recently, the storage capacities of electric vehicles are being deployed to dampen power fluctuations in smart grids. They are especially beneficial due to their large capacities, and the nullification of any investment costs, as well as their mobility. In this regard, a Vehicle to Grid (V2G) system is defined as discharging the vehicles’ batteries and injecting their energy back to the grid during peak hours, whilst charging them during valley hours. Nevertheless, the V2G systems suffer a minor incompetency; the low efficiency resultant from the losses in charging and discharging operations. This work aims at addressing this problem by designing a bi-directional converter that involves enhanced efficiency features. The converter contains an improved AC-DC bidirectional converter driven by sine wave pulse width modulation, feeding a dual active bridge DC-DC converter driven by a single-phase-shift modulation controller. The results indicated high power ratings, higher voltage gain, higher charging/discharging efficiencies, simple control system, and consecutively a better coordination between the grid and the electric vehicles achieved with minimal losses. The design is carried out on the SIMULINK simulation platform of MATLAB software, where the respective design was implemented and the results were discussed. 

An Improved Two-Stage Bidirectional Converter for Electric Vehicles to Grid Applications

Quite recently, the storage capacities of electric vehicles are being deployed to dampen power fluctuations in smart grids. They are especially beneficial due to their large capacities, and the nullification of any investment costs, as well as their mobility. In this regard, a Vehicle to Grid (V2G) system is defined as discharging the vehicles’ batteries and injecting their energy back to the grid during peak hours, whilst charging them during valley hours. Nevertheless, the V2G systems suffer a minor incompetency; the low efficiency resultant from the losses in charging and discharging operations. This work aims at addressing this problem by designing a bi-directional converter that involves enhanced efficiency features. The converter contains an improved AC-DC bidirectional converter driven by sine wave pulse width modulation, feeding a dual active bridge DC-DC converter driven by a single-phase-shift modulation controller. The results indicated high power ratings, higher voltage gain, higher charging/discharging efficiencies, simple control system, and consecutively a better coordination between the grid and the electric vehicles achieved with minimal losses. The design is carried out on the SIMULINK simulation platform of MATLAB software, where the respective design was implemented and the results were discussed.

In a home, off-board chargers are required to charge low voltage powered electric vehicles (LEVs) as well as high voltage powered electric vehicles (HEVs). Keeping this in view, this work presents the design and control of a single-stage bidirectional electric vehicle (EV) charger with a wide output voltage range from 72 V to 240 V. Moreover, the presented bidirectional EV charger facilitates the user to utilize the vehicle battery to supply the home loads, i.e. vehicle-to-home operation during the unavailability of grid power. A bidirectional bridgeless Cuk converter with a switched inductor is designed and analyzed for this EV charger. The main advantages of this bidirectional EV charger are regulated battery current and enhanced grid side performance with reduced component count during the bidirectional operation. The steady-state and dynamic performances of the designed battery charger are investigated under distinct operating conditions during EV charging and vehicle-to-home operation. At last, the efficacy of the battery EV charger is tested to comply with IEC 61000-3-2 standard for power quality and bidirectional operation with NEMA PE-5 standard towards battery current. 

A Bidirectional Electric Vehicle Charger for Wide Output Voltage Range Application

The small signal analysis of bidirectional single-phase single-stage AC-DC converter and its application for EV charging are presented in this paper. A unique control strategy for establishing soft switching without any additional circuit is developed utilizing the traditional state-space averaging technique. The small signal model in each mode of operation is presented. Using this model, current at the input of the ac side can be regulated to realize power factor correction (PFC) and also to regulate active and reactive power flow in either direction. Four quadrant operation of the converter can be utilized for improving the stability of the power grid. Controller designed using the derived small signal model is used to validate the operation as well as transition of the converter between V2G and G2V modes. Simulation results are presented to demonstrate four quadrant operation of the designed converter. Design of the converter, closed loop controller, and the results are presented for 1.5kVA converter.

Rajagopal Prasanna

Papers

Modelling and Control of Novel Bidirectional Single-Phase Single-Stage Isolated AC-DC Converter with PFC for Charging of Electric Vehicles