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It is well-known that in multiphase drives the spatial harmonics of the air-gap magnetic field can be controlled independently of each other. In this paper it is shown how the third-order spatial harmonic of the magnetic field can be used to estimate the rotor speed without the need of a mechanical sensor. Experimental results confirm the feasibility of the developed sensorless speed observer.
Condition monitoring of electric machines is a procedure of increasing importance, as fault tolerant systems are becoming mandatory in many applications. Early diagnosis of faults is a basic pillar in order to achieve full tolerance by the maintenance of faulty parts in electrical machines. As far as electrical drives are concerned, the share of mechanical faults (imbalances, gears and bearings) is...
Multiphase permanent magnet machines are becoming attractive alternative for a wide range of industry applications owing to their reliability, dynamic performances, and its greater degrees of fault tolerability compared to three-phase machines. In this context, diagnosing rotor magnets degradation at incipient stage is crucial to guaranty the required efficiency of the machines. In the present paper...
Rotor fault diagnosis techniques developed for induction machines (IMs) are classically based on current spectral analysis (CSA). For the case of rotor asymmetry in Wound-Rotor Induction Machine (WRIM), the magnitude of the negative sequence component at -sf of the rotor current space-vector is commonly monitored in order to quantify its contribution. Nevertheless, CSA still has some limitations....
In low-power photovoltaic systems, single-phase inverters are often used to inject the generated power into the grid. To increase the efficiency, the researchers have proposed to eliminate the transformer that connects the photovoltaic system to the grid. However, the absence of this transformer allows a leakage current to circulate through the ground, the parasitic capacitance of the photovoltaic...
Permanent magnet synchronous motors (PMSMs) are used for large variety of applications in industry, mainly because of their high efficiency suitable for automotive and traction systems. In this context, diagnosing stator faults is crucial for ensuring high motor performance and reliability. The influence of the Closed-loop (CL) control scheme must be considered when the diagnosis of stator asymmetry...
Fault detection in induction machines is commonly realized through motor current signature analysis. In case of Wound-Rotor Induction Machine rotor faults, the amplitude of the inverse sequence harmonic component -sf of the rotor current space-vector is monitored in order to sense its variation. However, motor current signature analysis is limited by some drawbacks. In fact, under transient operating...
The matrix converter rectifier is an AC-to-DC converter that can be considered for emerging applications, related to smart grids and renewable energy production. The most attractive characteristics of this converter are the simultaneous control of the input power factor and the output voltage, and the small volume of the input capacitors. In this paper, after a small review of the modulation techniques,...
An electric drive for high-speed applications is analyzed in this paper. The drive consists of a dual two-level inverter with a floating bridge, fed by a single voltage source, and a 3-phase induction motor with open-ended stator windings. The floating bridge compensates the reactive power of the motor, so that the main inverter operates at unity power factor and fully exploits its current capability...
This paper presents an electric drive consisting of a multiphase induction motor fed by a multiphase inverter. The control system is similar to that of a traditional field-oriented control for three-phase motors, but the machine speed is estimated by a novel sensorless observer. Since multiphase motors with M phases (M is supposed odd) have the capability of controlling the odd spatial harmonics of...
Various soft switching inverter topologies have been reported in the literature with the aims of reducing the switching losses and dynamic switching stress. However, lower losses are generally regarded as one of the most significant advantages of the emerging silicon carbide semiconductor devices over the conventional silicon devices. Both routes seem viable to improve the converter efficiency. To...
This paper introduces a diagnostic technique for the detection of mixed Stator-Rotor electrical faults in Doubly Fed Induction Machine (DFIM) for wind power systems. Operating in aggressive environments, the detection of anomalies at an incipient stage is crucial to decide about the operating continuity of the machines. In this paper the behavior of DFIM is investigated under the assumption that the...
This paper investigates a new approach for the diagnosis of Rotor asymmetry in Wound-Rotor Induction Machines (WRIM). The method is assessed in a Wind Energy Conversion System, where the rotor side of the WRIM is supplied by a static converter for the control of active and reactive power flows from the generator to the electrical grid. The control system affects electric quantities and their signature...
A speed control scheme is proposed for a 3-phase induction motor that uses an open-ended stator winding fed by a dual inverter system with a floating bridge. The floating bridge has a voltage boosting function that extends the constant power high-speed range of the induction machine and operates the main inverter bridge at unity power factor. The proposed control scheme coordinates the two inverters...
This paper provides an extensive overview of the control schemes that can be used for field-weakening operation of induction motors. Although almost all commercial drives offer this capability, a multitude of solutions have been proposed and the need of a classification arises. Therefore this paper attempts to illustrate the most used solutions that can be found in the literature. The control schemes...
Passive three-phase rectifier circuits are very popular for ac-dc power conversion. However, they do not have the capability to reverse the power flow, which is demanded by some recent potential smart-grid applications, such as vehicle-to-grid (V2G) power transfer. This paper compares two structures of reversible battery chargers, i.e., an interleaved dc-dc converter fed by a three-phase power factor...
Modular multilevel converter (MMC) is a promising multilevel topology for high-voltage applications that has been developed in recent years. The control of MMCs has been analyzed in detail in many papers, showing that the converter capacitors can be kept charged and balanced by controlling the circulating current of each leg. The set-point signal of the circulating current is probably the most difficult...
Multiphase permanent-magnet generators are an attractive alternative for a variety of emerging applications owing to their reliability and dynamic performance such as hybrid traction systems. In this context, diagnosing the status of the rotor magnets is crucial for improving the reliability of the generators. The effect of the closed-loop control system cannot be neglected when the fault detection...
Passive three-phase rectifier circuits are very popular for ac-dc power conversion. However, they do not have the capability to reverse the power flow, which is demanded by some recent potential smart-grid applications, such as vehicle-to-grid (V2G) power transfer. As an alternative, this paper analyzes the behavior of three-phase ac-dc matrix converters. Among the modulation strategies that minimize...
Design of modern Wind Energy Conversion Systems (WECSs) must take into account two crucial aspects: efficient control strategies and reliable monitoring and diagnosis techniques. Wind turbine generators based on Wound Rotor Induction Machine (WRIM) is actually the preferred technology mainly because of the lower rating of the power converter connected to the rotor side. With the association of a back-to...
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