Compensation of ripple power required during the$\mathbf{1}-\phi$operation of direct matrix converters needs to be addressed in order to improve their power density, reliability, cost effectiveness, etc. Literature survey reveals that compensation strategies relevant to matrix converters are usually implemented either at the low frequency AC side of the matrix converter or at the DC port side. In such cases, the entire ripple power needs to be handled by the compensation block, thereby effecting metrics such as voltage or current stresses, losses, power density, etc. In view of this, two circuits are described in this paper that perform active ripple power compensation of direct matrix converter based isolated bidirectional AC-DC converters while handling a fraction of the actual ripple power. The compensation circuits are operated at the high frequency link of the AC-DC converter on the DC port side. Relevant explanation of the working principle of the topologies are given, and simulation results for a 3.45$\mathbf{kW}$electric vehicle charger, with a 230 V (RMS) AC grid input, feeding a 400 V battery are presented to illustrate the findings.

Electric motors with high torque density are sought after in applications with constrained equipment footprint. In recent years, torque density enhancement is often being achieved by using magnetic gears with the motors. The gear ratio has a substantial impact on the relative size of the motor and the magnetic gear and eventually on the system volume and performance. This paper investigates the effect of gear ratio on the design and performance parameters of a magnetic gear integrated machine in two different ways. Firstly, five machines are designed for the same output torque and speed ratings but for different gear ratios. In another set of five machines, magnetic gears of different gear ratios are integrated to the same motor to determine the trend and limitation in torque density enhancement. These designs are optimised with finite element analysis for a fair comparison. A magnetic gear integrated segmented rotor switched reluctance motor has been chosen for this study. The optimised designs are compared for material mass, loss, footprint and efficiency. Guidelines are provided towards the choice of gear ratio for magnetic gear integrated electric motors.

A Two stage on-board electric vehicle charger (OBEVC) has a front-end power factor correction (PFC) converter and a dc-dc converter to charge the main battery. In addition, there is an isolated dc-dc converter, typically one-third the rating of the main battery charger, to supply various auxiliary low voltage loads. In this paper, a new on-board charger consisting of fewer circuit components and having a higher power density compared to the converters reported in the literature, is proposed. This is achieved by completely eliminating the isolated low power dc-dc converter. In grid connected mode, Totempole PFC and dual active bridge (DAB) perform either grid to vehicle (G2V) or vehicle to grid (V2G) operation with main battery. In driving mode, an interleaved buck converter is formed using the first stage circuit (Totempole) components. The second leg of Totempole PFC is integrated with ripple power compensation (RPC) circuit to eliminate the second order ripple power in the dc link. It also serves as one of the phases for interleaved buck converter in driving mode. The DAB along with interleaved buck converter supply power to the auxiliary battery and low voltage loads. The operation of this converter is explained and detailed simulation studies on a 7.2 kW on-board charger are carried out.

Breaking of fault current in dc microgrid has been a challenge due to lack of dc current zero crossing. The fault current in case of pole to pole fault is high and even higher in the presence of multiple generators as all the generators feed current to the fault. This results in very high current in the faulted line. Clearing such high fault current is difficult. Many methods have been proposed in literature to maintain low current during fault for ease of fault clearing. This paper presents a fault ride through (FRT) techniques for the generator to limit the current fed during fault. The proposed FRT scheme limits the fault current to a minimum value by feeding a minimum current into the network. The minimum current is derived based on the characteristics of the source and operating strategies of converter. The proposed FRT scheme ensures fast recovery of the network voltage. The proposed FRT scheme is verified through detailed simulations in Simulink.

In this paper a transformer coupled multi-input dc-dc converter (TCMDDC) based solar photovoltaic system for standalone applications is proposed. The proposed TCMDDC can realize maximum power point tracking and battery charge control while maintaining proper voltage level. In the process it allows reduction in number of power conversion stages as compared to the existing standalone schemes. This leads to enhancements in efficiency and reliability of the proposed scheme. Further, it allows the use of low voltage levels for solar PV array and battery thereby eliminating concerns pertaining to the safety of personnel and equipment. A suitable control strategy that allows the TCMDDC to operate in different modes that are encountered in a standalone scheme is also devised. The viability of the scheme is ascertained through detailed analytical and simulation studies.

Stand alone PV based systems for household applications require reliable and efficient power converter configuration along with good battery performance. This paper introduces a reliable, efficient and reduced stage PV based power generating unit using battery as an energy storage element. In this paper, a transformer coupled half-bridge boost converter has been used for harnessing power from PV, along with a bidirectional converter for battery charging/discharging control and a single-phase inverter for connecting to AC loads. A control scheme for the system has been proposed for controlling output voltage, inverter dc link voltage, MPPT of PV and battery current. The scheme has been validated by performing detailed simulation studies.

Load compensators have become popular because of the enhanced concern over deteriorating power quality figures caused due to the proliferation of power electronic based systems which pose themselves as non-linear type of loads to the utility. Modern load compensators have better filtering performance, small physical size, and more flexibility in application, but are still not very competitive in terms of its cost and increased losses compared to traditional passive filters, especially if it is used for compensating reactive power requirement of the load. Innovative and advanced controllers like one cycle control (OCC) having fast transient response and which do not require the service of a phase locked loop (PLL) have been used for active load compensation. But existing OCC based load compensators do not have the capability to distinguish between fundamental reactive component of the load current and its higher order harmonic components and end up compensating for both. This leads to an increase in the rating of the converter. The proposed OCC based shunt harmonic filter compensates only for the harmonic component of the load current, while retaining the advantages of the original OCC based schemes.