Multiphase motor drives offer better advantages in high-power motion control applications as they can handle more power with reduced power per phase, lower-order harmonics, reduced input filter size, etc., compared to the classical 3-phase (Φ) systems. The symmetrical 6-Φ voltage source inverter (VSI)-fed interior permanent magnet synchronous motor (IPMSM) drive controlled by the conventional space vector pulse width modulation (SVPWM) results in different common mode voltage (CMV) levels. This rate of change of CMV is responsible for the flow of the common mode (CM) current, which can lead to premature bearing damage in motor loads. To circumvent this problem, this paper proposes two new SVPWM-based PWM variants for the symmetrical 6-Φ VSI drive that are aimed at attaining a constant CMV level, thereby completely avoiding the changes in CMV. The proposed PWM variants are designed in such a way that they closely mimic the 3-Φ SVPWM principle, making the implementation of SVPWM for the 6-Φ VSI very simple and thus decreasing the complexity of dwell time calculations for the 6-Φ VSI system. Detailed simulation studies using MATLAB/Simulink are presented to support the proposed PWM variants with vector control implemented under speed and load disturbances, including speed reversal following V/f control.

For large-scale energy storage applications, variable-speed pumped hydro storage plants (VS-PHSP) are a proven solution due to their fast start-up and high ramping capabilities. Variable-speed operation is primarily dependent on power electronic converters. However, existing converter topologies often suffer from drawbacks, including a large number of semiconductor devices, the need for series-connected switches, and non-uniform voltage distribution, which result in increased losses, complex cooling requirements, and overall system cost. To overcome these challenges, this paper proposes a back-to-back configuration of a new four-level converter for VS-PHSP systems. The proposed topology eliminates the requirement for series device connections and ensures uniform voltage sharing among switches. Subsequently, it reduces the overall device count and their cost. In addition, a model predictive control for the proposed back-to-back configuration is implemented and validated through MATLAB simulations.

The main issues impeding wide adoption of electric vehicles (EVs) are limited driving range and longer battery charging time. Recently, there has been a shift from traditional 400 V battery charging systems (BCS) to next-generation 800 V BCS owing to advantages such as reduced battery charging time and weight savings in the EVs. The dual active bridge (DAB) converter and resonant converters are typically used in the isolated bidirectional dc-dc conversion stage (IBDCS) in EVs. Among which DAB converter is a popular choice because of simplicity in control, inherent bidirectional power flow and soft-switching capability. The performance of the conventional DAB topology however gets compromised when operating over such a wide battery voltage range. This paper proposes a reconfigurable DAB (r-DAB) converter for the IBDCS of EV charging infrastructure to cater to the wide voltage range requirements of traditional/next-generation of EVs. Besides, the proposed r-DAB converter facilitates bidirectional power flow capability that can support the grid during peak load demands. In this paper, the operational aspects and the control structure of the proposed r-DAB converter are analyzed in detail and the same are validated through PLECS simulations.

Electric city buses usually possess a large battery pack and demand overnight charging at the depot. As a result, it offers a high capital cost, longer charging times, and limits the passenger capacity. Opportunity charging of electric vehicles (EVs) during brief stops is considered to be one of possible solutions to conquer these problems. This paper presents a prospective battery sizing methodology and charger evaluation of electric city buses enabled by wireless charging at frequent stops to achieve driving range extension while minimizing battery size. The quasi-instantaneous power connection can be possible using wireless power transfer (WPT) charging technology. Battery size reduction and range extension of electric city buses employing opportunity wireless charging is illustrated for various WPT charger power ratings under Federal test procedure (FTP) drive cycle and New European driving cycles (NEDC).

Range anxiety, lack of charging systems and cost are the main concerns for fast adoption of electric vehicles (EVs). Battery chargers decide the performance and life cycle of the battery packs. Therefore, battery chargers play a vital role to escalate the penetration of the Plug-in EVs (PEVs). PEV battery chargers are classified into onboard and off-board chargers based on its availability inside or outside the vehicle. Onboard chargers do not need any additional infrastructure, which can be easily and directly charged from the ac mains. This paper aims to review the technological status of onboard charging infrastructure including front-end power factor correction (PFC) converters and the battery interface converters. The merits and demerits of all the charger topologies are discussed in detail. Finally, a single-phase 1.4 kW onboard charger with interleaved boost PFC as a front-end converter and phase-shifted full-bridge converter as a battery interface is designed and simulated in the PLECS software platform.

After steam engine-based propulsion systems became outdated due to the poor efficiency issue, gas turbine and diesel engine-based propulsion systems found popularity. The efficiency of combustion engines is optimum only when it is operated close to the rated load. It also suffers from vibrations, higher fuel consumption, frequent maintenance requirements, and a lack of flexible and redundant operations. Few hybrid propulsion systems such as thermal combined and gas-electric came into existence to address these issues. However, they required geared transmission system, deteriorating efficiency and increasing the maintenance requirements. Hence, electrification of marine systems is considered crucial to empower future marine propulsion systems (MPS). This paper reviews the merits and demerits of contemporary multilevel inverter (MLI) topologies, which are potentially believed to enhance the performance of electric propulsion systems (EPS) for marine applications. A detailed comparison and simulation results of contemporary MLI topologies to drive the MPS are presented with their respective five-level configurations. Simulations of different five-level MLIs for the load of 5 MVA are done using PLECS software.

Following the successful commercialization of road-going electric vehicles, zero-emission electric marine vessels are gaining industry focus for absolute battery operation. Due to the low energy density of lithium-ion batteries, low propulsion-powered marine vessels operated frequently over short distances are found suitable for complete battery propulsion. In this paper, a modular multilevel converter (MMC) with symmetrically decentralized onboard battery banks is proposed as a marine traction inverter for a multi-purpose harbor vessel. A novel mathematical model of the marine vessel is proposed to size the propulsion motor, and generate torque-speed commands corresponding to vessel speed during the maneuver. A brief analytical discussion has presented on the selection of motor-converter configuration for marine propulsion application, considering three-phase low-voltage permanent magnet synchronous motor (PMSM) with a two-level inverter and three-phase medium-voltage PMSM with MMC. A short endurance marine drive cycle is simulated with low-speed high torque three-phase PMSM driven by MMC with integrated battery modules (BM). This study leveraged MATLAB/Simulink environment to analyze the operational performance of MMC and BMs during various phases of the short endurance marine drive cycle.

The modular multilevel converter (MMC) has emerged as a captivating multilevel converter topology for medium to high-power applications. Due to aging and chemical process, the impedance characteristics of the capacitor in the submodule (SM) changes. This can result in an increase of SM capacitor voltage ripple and unequal power distribution among the SMs in the arm. Furthermore, prolonged use of degraded capacitors could interrupt the normal operation of the MMC. Existing SM capacitor voltage balancing approaches for the MMC are based on an assumption that all SMs have equal capacitance and ignore the component degradation. Hence, there is a need for closed-loop balancing control techniques that use instantaneous monitoring of capacitor parameters to enhance the reliability of the MMC. This paper addresses this gap by introducing an energy-based balancing control of SM capacitors, which effectively balances and controls the energy distribution among the SMs in the arm under the capacitor degradation. For validation of the proposed control strategy, detailed simulation studies are carried out for half-bridge SM based MMC in PLECS software platform.

The pivotal features of low self-discharge, high energy density and long calendar life lead the Lithium-ion (Li-ion) batteries as being a mainstream energy storage source in electric vehicles (EVs). A meticulous estimation of the state of charge (SOC) is indispensable for ensuring safe and reliable operations in battery powered EVs. However, SOC estimation of Li-ion battery with high accuracy have become a major challenge in the automotive industry. To fulfill reliable operation in EVs, researchers have proposed numerous SOC estimators through model based or machine learning techniques. This paper presents an improved SOC estimation of Li-ion battery using random forest (RF) regression, which is robust and effective for controlling dynamic systems. To ensure good resilience and accuracy, a Gaussian filter is adopted at the final stage to minimize the variations in the SOC estimation. The proposed SOC estimator is verified on the experimental data of the Li-ion battery under Federal test driving schedules and different operating temperatures. Results show that the proposed SOC estimator displays sufficient accuracy and outperforms the traditional artificial intelligence based approaches.

The modular multilevel converters (MMCs) have emerged as one of the promising topologies for medium/high power applications. The aluminum electrolytic capacitors (AECs) are usually employed in the MMC as floating capacitors due to their high volumetric efficiency and low price. The AECs are reported as one of the most fragile components in the converter, which gradually deteriorates over the time due to vaporization of the electrolyte. As a result, its capacitance decreases and equivalent series resistance (ESR) increases with ageing, which can result in an increase of submodule (SM) capacitor voltage ripple, power loss and could damage the operation of the MMC with prolonged use of the aged capacitors. Therefore, health monitoring of SM capacitors is essential to enhance the reliability of the MMC by predictive maintenance. This paper presents a new health monitoring technique for SM capacitors in the MMC utilizing inherent SM capacitor voltage fluctuations. The capacitance is estimated by second-harmonic impedance, which is evaluated using the ripple in capacitor voltage and current. The proposed method utilizes the available measurement used for the converter control and can be easily implemented in the same converter controller. The proposed scheme is verified for five-level MMC through simulation results in PLECS software.

The modular multilevel converter (MMC) employing multilevel submodules (SMs) displeys a reduced footprint size, voltage ripple and an improved efficiency compared to standard SMs. Due to capacitor voltage fluctuations in the SMs of the MMC, circulating current (CC) flows among the phase-legs. These currents can affect the system efficiency and menace the safe operation of MMC. Therefore, an active closed-loop CC controller is imperative for reliable operation of the MMC. The classical methods exhibit an awful steady-state performance, limited harmonic filtering, instability during load variations and complexity in digital implementations. This paper introduces a pseudo-derivative-feedback (PDF) based CC suppression control of the MMC in synchronous dq-frame. The design and implementation of the PDF controller are presented and adapted to minimize the CC. The theoretical analysis and numerical results obtained through simulations in PLECS software platform for seven-level flying capacitor SM based three-phase MMC are presented to verify the advantages of the PDF-based CC control.