A squirrel cage induction generator (SCIG) system experiences the change of parameters due to variation in temperature, change of load demand, or minute variations in mechanical fabrication. Therefore, a conventional PI controller for DC-bus voltage with active front-end rectifier (AFE) is subjected to controller’s parameter tuning with system aging and load change. In this paper, a DC bus voltage control technique is realized utilizing root-locus based pole-zero placement technique. This DC-bus controller places poles and zeros at a desired location of the system root-locus, which gives the benefit of parameter invariant response. This mathematical analysis of voltage control technique and its implementation is explained in detail for SCIG. The voltage controller follows the conventional current controller design for an indirect field-oriented power control (FoPC) for a fixed speed SCIG. The overall control is investigated and tested in PLECs simulation platform, and the results are presented for various load dynamics operations.

The development of DC microgrids has accelerated due to their excellent compatibility with DC sources and loads. In these systems, the Triple Active Bridge (TAB) converters have emerged as key components, establishing a versatile three-port network that integrates distributed energy resources (DERs), battery energy storage systems (BESS), and loads. Given the susceptibility of these systems to disturbances and failures, ensuring fault-tolerant operation is essential. This paper proposes an enhanced TAB converter design with enhanced fault-tolerant capabilities, achieved through the addition of only two IGBTs and one diode to the conventional topology. Furthermore, a novel control strategy is presented for the proposed TAB, enabling seamless transition to Buck/Boost mode during short-circuit faults and rapid mitigation of open-circuit faults in switches, thereby ensuring continuous operation. The effectiveness of the proposed topology and control strategy is validated through simulation.

Microgrid is a promising way to integrate renewable energy. However, if microgrids connect to the grid dispersedly without regulation, it will cause power fluctuation and voltage violation. To manage microgrids in an autonomous and decentralized way and address these challenges, this paper presents a two-stage strategy for a microgrid connected to a DC grid to realize optimal energy management considering both dayahead and real-time aspects. From the day-ahead perspective, the proposed strategy incorporates both DC grid and microgrid to establish a grid-supporting microgrid at minimal cost. For the real-time strategy, the proposed strategy can mitigate voltage fluctuations by flexibly adjusting the coefficient of the P(V) curve which is generated based on day-ahead results using a PI controller. The simulation results demonstrate the effectiveness of the proposed strategy.

A 21-concentric 42-sided polygonal space vector structure (SVS) for suppression of lower order harmonics for Open-End Induction Motor drive applications is proposed in this work. The Open-End Induction Motor is fed with primary and secondary inverters from either side. The primary inverter providing active power for motor operation is fed with an active DC link. The primary inverter is switched at low switching frequency to minimize stress on high voltage switching devices. As a result, the primary inverter consists of lower order harmonics in the pole voltage. The secondary inverter is employed only to suppress the harmonics generated by primary inverter and does not contribute any active power for motoring operation. Hence, the secondary inverter can be fed with a capacitive supply balanced at a nominal voltage. The secondary inverter, operating at lower voltages is switched with high frequency to suppress the lower order harmonics upto 39thorder in the motor phase voltage. The advantages of polygonal space vector structures are retained throughout the modulation index, by generating 21-concentric layers of 42-sided polygons. This results in lower switching losses in low frequency switching main inverter and low voltage secondary inverter. A single DC link is employed in the power circuit topology to facilitate four-quadrant operation of the inverter. The proposed scheme is tested in MATLAB simulations and laboratory prototype. The simulation and experimental results are presented.

Torque smoothness is an essential requirement for high-performance motor drive applications. Synchronous reluctance machines have high torque ripple due to non-linear magnetic path coupled with saturation of the rotor core segments during operation. This paper proposes an active torque ripple minimization technique for Synchronous reluctance machine using current injection. The proposed method is aimed to compensate for both cogging and torque ripple generated by the machine. The method also optimizes for the minimum magnitude of ripple injection for active cancellation. The effectiveness of the proposed method is evaluated with both simulation and experimental results.

The objective of this paper is to propose a new control strategy for synchronous reluctance machines (SyRM) to mitigate the parameter saturation problems. The paper also highlights the reasons for the difference in the saturation behavior between the permanent magnet motors (PM) and the SyRM using the FEA flux distribution results. The synchronous reluctance machine is devoid of rotor magnets (in contrast with the PM machines) and it solely relies on reluctance portion to produce torque. This gives the SyRM machines the advantage of lower cost and more reliability compared to PM machines. But the lack of magnets in SyRM causes the motor parameters to saturate more quickly compared to the PM machines. The optimal control of the SyRM machine is thus strongly dependent on the controller’s ability to adapt to the fast changing saturation in the SyRM machine. The control strategy proposed in the paper uses a reference current generation block that optimizes the reference current for the saturation that would occur in the machine at any point in operation. A d-q voltage and current sign estimator reduces the controller iterations considerably to reach to a solution. The simulation and experimental results are presented for a 30 slot 4-pole SyRM machine.

Electric vehicle (EV) battery charging application requires power converters with higher efficiency and power density. Soft-switched single stage power converters can be suitable for this application as they require lesser number of active and passive components compared to the conventional two stage converters. This paper presents two isolated single phase single stage AC-DC converter topologies for EV application. These converters operate under zero current switching (ZCS) condition. A regenerative flyback based snubber circuit is also presented to mitigate voltage spikes resulted due to the leakage inductor of the high frequency link transformer. A detailed analysis of converter operation is presented in this paper. Key experimental results are shown to validate the performance of these converters in a 1 kW prototype.

Reliability of DC grid is measured in terms of fault interruption time of the switchgear. Unlike AC systems, DC systems do not encounter zero crossing of fault current. Hence the DC circuit breaker should be capable of very fast fault interruption and isolation. Solid state circuit breakers (SSCB) exhibit fast fault interruption at the expense of substantially large conduction power loss due to on-state drop of semiconductor devices. Hybrid circuit breakers yield better performance in terms of efficiency although the principal hurdle remains in demagnetization of network inductance after mechanical breaker is completely turned off. This paper proposes two hybrid DC circuit breaker (DCCB) topologies using coupled inductor to mitigate this issue. The coupled inductor forms a resonant circuit with a commutation capacitor during the fault to turn off the mechanical switch at zero current. Commutation capacitor is charged through the circuit elements; hence the requirement for external pre-charging circuit is eliminated. Moreover, the capacitor is charged to unipolar DC voltage only, enabling use of electrolytic capacitor. Proposed topologies do not require surge arrester to demagnetize the DC network once fault is cleared. One of the proposed circuit breaker topologies is designed for bidirectional power flow, implying its use in multi terminal DC transmission system or DC micro-grid. Detailed analysis and design of the proposed circuit breakers are presented in this paper and validated through simulation and experimental results.

This paper presents a nine level inverter topology with only eight switches per phase, for driving an induction motor with open end stator winding. The topology consists of two three-level, three phase inverters connected to the two ends of the induction motor. With asymmetric DC link voltages in a ratio of 3:1, an effective nine level space vector structure is realised. Modulation is done using level shifted carriers, which requires only sampled values of the three phase voltage references. Switching state redundancies are used effectively to ensure that both inverters supply real power to the load over the entire modulation range preventing overcharging of the DC links. In case of a fault in one of the inverters, the faulty inverter can by bypassed and operation is possible using the other inverter. The topology was simulated using MATLAB/Simulink and experimentally verified over the entire linear modulation range. Experimental results validating the proposed scheme are included.

The open-end winding machines can be fed by two three-phase inverters. In each phase, three-level voltages are generated by an H-bridge. Three-level PWM can reduce current ripple in α-β frame by using the voltage vectors on the vertices of small triangle. For open-end winding configuration, PWM methods which use the small triangle have been implemented with space vector modulation based techniques. These techniques modulate the voltage by switching one inverter while clamping the other inverter. To distribute switching stress, the role of switching and clamping are alternated between the two inverters based on the area in α-β frame. However, the switching stress is still concentrated to one inverter in low speed because the role change depends on the electrical angle. In this paper, a PWM method which uses the small triangle without clamping the output of inverters is proposed. The method is implemented with carrier based technique. It is realized by alternating two carrier waves which have 90° phase difference depending on the polarity of the reference voltage. The experimental results show that the proposed method can reduce the α-β current ripple as well as the conventional method with clamping.

In more electric aircraft (MEA), supplying constant voltage variable frequency (CVVF) AC power to frequency insensitive loads (eg. wing de-icing system, galleys, etc.) in DC primary distribution system requires an AC-DC-AC conversion which adds losses and additional hardware installment to the system. This paper presents a novel open-end winding induction generation system supplying CVVF AC power for MEA As a subsystem of an AC/DC hybrid generation system, this CVVF induction generation system uses a series connected inverter-load topology without any energy storage device. A current oriented control scheme is used to regulate both AC and DC side voltages of the system without battery compensation. The proposed series connected induction generation system presents reduced hardware footprint compared to conventional shunt connected and battery compensated series connected induction generation system. The performance of the proposed system is demonstrated by simulation in MATLAB/SIMULINK.

In this paper, high bandwidth current control for an open-end winding induction motor is realized with deadbeat control. A deadbeat current controller achieves higher gain than a PI current controller by compensating for the error caused by the digital sampling delay. The response of a deadbeat controller is directly influenced by its sampling frequency, while that of PI controller depends on gain tuning. In this paper, a quarter carrier period sampling of current controller is proposed for control of an open-end winding induction motor. In the proposed method, the sampling frequency is doubled as compared with the conventional half carrier period sampling method. Thus, the frequency response of the deadbeat current control is improved with this quarter carrier period sampling. The validity of this high bandwidth current controller is verified by simulation.

This paper proposes a new hybrid space vector pulse width modulation (SVPWM) strategy to minimize the neutral point voltage ripple of a three-level T-type converter. The origin of neutral point voltage ripple is analyzed in detail. Then, the controllability of a nearest three vectors (N3V) based SVPWM on the neutral point voltage balancing is investigated. In the uncontrollable regions of the N3V SVPWM approach, a non N3V based SVPWM is incorporated to balance the neutral point voltage with a switching cycle based profile. The non N3V based SVPWM is realized by replacing the medium voltage vector of the three nearest vectors (NVs) with a large voltage vector in an appropriate way. By introducing an offset vector, the reference voltage vector of the three-level converter can be synthesized in a way similar to that of a two-level converter. The effectiveness and the advantages of the proposed hybrid SVPWM scheme are verified by the simulation results in Matlab @ Simulink.

Fault tolerant and survivable operation schemes for multi-level converters, that interface the grid and critical loads, have been gathering attention for enhanced reliability. In case short-circuit or open-circuit faults occur in one or multiple voltage cells, the space vector pulse width modulation (SVPWM) control algorithm has to be modified according to the available voltage vectors for survivable operation. This paper proposes a new fault tolerant SVPWM strategy based on offset vector insertion, which allows controlling the multilevel converter as a two-level converter. A robust offset vector locating algorithm, which finds the feasible offset vector in case of short-circuit and open-circuit conditions, is presented. A single voltage cell short circuit fault is demonstrated on a seven-level hybrid input-switched multi-level converter to prove the effectiveness of the proposed survivable scheme.

Introduction of dynamic pricing in present retail market, considerably affects customers with an increased cost of energy consumption. Therefore, customers are enforced to control their loads according to price variation. This paper proposes a new technique of Home Energy Management, which helps customers to minimize their cost of energy consumption by appropriately controlling their loads. Thermostatically Controllable Appliances (TCAs) such as air conditioner and water heater are focused in this study, as they consume more than 50% of the total household energy consumption. The control process includes stochastic dynamic programming, which incorporated uncertainties in price and demand variation. It leads to an accurate selection of appliance settings. It is followed by a real time control of selected appliances with its optimal settings. Temperature set points of TCAs are adjusted based on price droop which is a reflection of actual cost of energy consumption. Customer satisfaction is maintained within limits using constraint optimization. It is showed that considerable energy savings is achieved.