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An original overvoltage mitigation technique is presented in this paper for Sic based motor drives, exploiting an open-end winding motor configuration. According to the proposed solution over-voltage occurring at the terminals of the motor phases is mitigated by driving the two inverters through a modified switching pattern including a suitable dwell time. No passive RLC networks are required, thus...
This paper deals with a self-sensing control for Open-end Winding Permanent-Magnet Synchronous Motors fed by Asymmetrical Hybrid Multilevel Inverters. In this kind of system, a main multilevel inverter (MLI) supplies the PMSM on one side, while an auxiliary two-level inverter (TLI) acts as active power filter on the other side of the machine. The MLI works at a low-switching frequency and high voltage...
On Multiple-Motor systems fed by Multiple-Converter systems a set of electric motor drives share the load through a common mechanical coupling. Such a coupling is exploited in this paper to realize a sensorless field oriented control, based on a quite common back-emf technique to estimate the rotor flux angular position and an original approach to correct the estimation errors. The technique is based...
This paper presents a three-phase six-level Asymmetrical Hybrid Multi-Level Photovoltaic Inverter (AHMLPI) for medium voltage grid connected applications. A Low to Medium Voltage Transformer is operated in an open-end winding configuration. Thus the low voltage winding is supplied on one end by a three-phase three-level Neutral Point Clamped Inverter (NPC) and, on the other side, by an auxiliary Two-Level...
Energy harvesters are today gaining ever more interest, enabling the recovery of otherwise wasted energy in a large variety of systems. Among them, piezoelectric devices are particularly suitable to generate electrical energy from vibrations and surplus mechanical energy. A two-stage power conditioning circuit, consisting of a AC-DC converter followed by a DC-DC stage, is usually placed at the output...
An Open-end Winding approach to the design of multi-motor drives exploiting multi-level inverters is presented in this paper. A key feature of the proposed approach is that a single multi-level inverter is tasked to provide the entire active power required by the system, while a two-level inverter acts as a power filter, providing a zero average active power. Moreover, a staircase voltage modulation...
A new approach, based on a current controlled Asymmetrical Hybrid Multilevel Inverter (AHMLI), is proposed to reduce power losses and output current distortion on Multi-Level Inverters (MLI) used in AC motor drives, STAT COM devices, Photovoltaic and Wind generators. A key feature of the proposed approach is that the AC machine (motor or transformer) is operated in an open-end winding configuration,...
A two-stage converter working in dual mode time sharing is proposed for single-phase photovoltaic applications. The converter encompasses a dual boost front end and a single-phase three-level Neutral Point Clamped grid inverter. According to the time sharing strategy, the boost stage is by-passed and only the Neutral Point Clamped inverter is operated when the input voltage is greater than the actual...
An over-voltage mitigation technique for open-end winding electrical drives with long power cables is proposed in this paper. In particular, a suitable dwell time is included in the switching patterns of the two inverters to minimize the over-voltage occurring at the stator terminals of this kind of systems. No passive RLC networks are required, thus avoiding additional costs and extra power losses...
In open-end winding AC motor drives, terminals of stator phases are normally connected between two inverters, normally, of the same type and size. In the present paper, an alternative configuration is studied where the machine is supplied exploiting two different converters: a main multi-level inverter and an auxiliary two-level inverter. The last operates as active power filter in order to eliminate...
Grid connected photovoltaic plants for residential applications are normally designed through deterministic methods on the basis of system requirements as: PV array peak power, available budget, or available space. Unfortunately, these approaches give only suboptimal results. More effective design techniques are those oriented to fulfill given performance targets as minimum pay-back time, minimum...
Electrically Assisted Internal Combustion Engines are gaining a large popularity, as they allow to obtain a noticeable average vehicle efficiency improvement at a low cost. Two different approaches are considered in designing last generation vehicles: StartStop, or Micro-Hybrid, and Electrically Assisted Turbocharger. The energy balance of a vehicle equipped with electrically assisted internal combustion...
The paper describes a simulation framework able to accomplish a simulation of a PV plants including a Wireless Sensor Network (WSN). The developed framework is entirely implemented in a Matlab/Simulink environment, and can be used to accomplish in-depth performance evaluation of two very different systems interacting between them, the power generator and the wireless data transfer network. As an example,...
Among single stage, single phase, inverter configurations the Neutral Point Clamped topology is advantaged by its quiet rail switching mechanism, producing negligible common mode currents. However, it requires a double input voltage if compared with a classic full bridge inverter. A modified Neutral Point Clamped, three level, single phase, inverter topology is presented in this paper intended for...
Thanks to an inner redundancy, AC Multi-Drives can be made fault tolerant with minor modifications of their structure. However, some additional components are generally required in order to create emergency current paths in case of a fault. According to a recently presented approach the amount of additional components can be reduced by exploiting healthy drives to support faulty drives. In this case...
A strong demand of even more compact and reliable power electronic devices has powered in the last years the development of advanced device design techniques. A key role in these techniques is played by the reliability assessment, a procedure that estimates the expected lifetime of power devices according to given mission profiles. The reliability assessment of a low voltage MOSFET working in avalanche...
A possible alternative to traditional, time crunching, endurance tests in accomplishing the reliability assessment of power devices are reliability models. Two possible approaches are compared in this paper to estimate the level of reliability of power MOSFETs working in avalanche mode. Although both the considered approaches exploit mathematical models carried out from the Coffin-Manson law, they...
Thanks to their characteristic quiet rail switching mechanism, derivatives of the basic half bridge converter, such as the Neutral Point Clamped topology, are advantaged among single stage, single phase, inverter configurations for PV applications by very low ground currents. On the other hand, as the majority of single stage inverters, they are unable to boost the input voltage, therefore featuring...
The paper deals with the development of a mathematical model of an active anti-rolling system for yachts and luxury boats, tailored around a pair of fin stabilizers driven by Permanent Magnet Synchronous Motor drives. Based on such a model, dynamic and energetic performance of the stabilizing system can be analyzed either with the boat cruising and the boat at anchor. The developed model can be exploited...
Sensorless motor drives are claimed to be more reliable than their sensored counterparts, as they avoid electromechanical sensors, additional wires and circuitries. However, the assertion is true only in normal operations. In fact, if on one hand the elimination of electromechanical, and electronic devices increases the drive reliability as a small number of parts subjected to possible faults are...
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