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Nowadays the evolution of electrical engineering achieved a successful expansion in the area of fault tolerant electrical machines. To achieve fault tolerance researchers tried to design various geometries and different electrical drives. When new designers are intended to be performed the knowledge of the actualstate of the work is impetuously nee...
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Context 1
... it was stated out before another possibility for achieving fault tolerant electrical machines is by changing the winding arrangement. Usually windings for each machine have their typical well-known arrangements. A first possibility is to assure an independency between the phase windings in the machine. Usually high number of coils and a high number of phases are applied in order to reduce the effects of winding damages. Fractional slot concentrated arrangements in a machine with permanent magnets embedded in the rotor assure higher torque density, negligible cogging torque and also small torque ripple [10]. The machine described in [10] had 30 slots and 28 poles of magnet. So in the 30 slots, the 5 phases gave 6 slot throw, practically giving a complex winding system, and due to this a complex drive, too (Fig. 5). An other idea should be dubling the stator poles. This demands also for doubling the number of phases of the winding system. This can be done by having multiple stator poles defining multiple stator slots, and at least two sets of stator windings, wound on the stator poles, so this way the end windings are shorter, and they are not overlapping. One set of windings can be placed in the upper half of the stator, and the second one in the lower one [11]. Connections between coils are set regarding the electrical drive that feed and command the machine. In case of winding short circuits, the fault must be isolated and masked by the inverter. For this, independency between same phase windings on different poles must be considered as leading concept. The task is to find the optimal solution for connecting the phase windings to the inverter, and defining the best winding type. In [12] a comparative study is given regarding two machines, with concentrated and distributed windings. It was proved that optimal for fault tolerant variants are the concentrated winding ...
Context 2
... a machine with permanent magnets embedded in the rotor assure higher torque density, negligible cogging torque and also small torque ripple [10]. The machine described in [10] had 30 slots and 28 poles of magnet. So in the 30 slots, the 5 phases gave 6 slot throw, practically giving a complex winding system, and due to this a complex drive, too (Fig. ...
Citations
... Beside applying the most dependable solutions, also their fault tolerance has to be considered [18], [19], [20]. In the case of electrical machines these basic requirements can be achieved by using simple and robust constructions, machines having high number of phases with very good phase separation, splitting the coils in independent channels, etc. [21], [22]. ...
... The switched reluctance motor (SRM) due to its robust and simple construction and to the magnetic independence of its phases is inherently one of the most fault tolerant motors on the market [1]. Combining the fault tolerance increasing solutions cited in the literature [2], [3] and [4] with an innovative modular construction of its stator a novel SRM was developed, which is very reliable and quickly repairable. Its performances were improved by minimizing its torque ripples by estimating and controlling the developed instantaneous torque. ...
The relatively high torque ripples are one of the main disadvantages of the switched reluctance motors. By smoothing their torque they can become more competitive for variable speed drives used in automotive and industrial applications. One of the most promising approaches to reduce the torque ripples of a SRM is the use of a direct instantaneous torque controller. In the paper the effectiveness of this type of control will be proved for a fault tolerant segmental stator SRM. By advanced simulation techniques the working principle of the direct instantaneous torque controlled drive system is illustrated, and its performances are demonstrated.
... Each variant has its advantages and drawbacks. A detailed survey on fault tolerant electrical machines can be found in [7]. ...
Fault tolerance is an obligatory feature in safety critical applications (aeronautical, aerospace, medical and military applications, power plants, etc.), where loss of life, environmental disasters, equipment destructions or unplanned downtimes must be avoided. For such applications, a novel bio-inspired motion control system is proposed. All its three components (the switched reluctance machine, the power converter and the control system) are designed to be as fault tolerant as possible. This paper describes all these three fault tolerant components: the bio-inspired control system having self-healing capabilities, the power converter with an extra leg and the fault tolerant modular machine. The theoretical expectations and simulation results are validated by means of laboratory experiments.
... Each variant has its advantages and drawbacks. A detailed survey on fault tolerant electrical machines can be found in [7]. ...
... Finally, the objective of the decision system is to initiate an action upon fault detection, which can be a safe shutdown of the drive or a warning to an operator, who initiates or re-schedules a shutdown of the drive/plant and an inspection. A reconfiguration of the drive to mitigate the fault propagation is also an alternative, assuming the drive is fault-tolerant to short-circuit faults [31][32][33][34][35][36][37][38]. Regarding PMSMs, the requirements are: large inductances (>1pu), an appropriate design preventing demagnetization of the magnets and a topology allowing the machine to be operated with a part of the winding shorted, e.g. with dual threephase windings. ...
This paper deals with an on-line method for turn-to-turn short-circuit fault detection in low-voltage permanent-magnet synchronous machine drives. Due to the closed-loop control, the fault effects are reflected in the voltage. Therefore, an appropriate diagnostic index is proposed, which is derived from the positive- and negative-sequences of the voltage references. These sequences are obtained in the time domain via adaptive filters, which require only a few calculations. To increase the sensitivity to the fault, the algorithm is only applied to a part of the voltage references, i.e. the output of the proportional-integral controllers. Further, the cumulative-sum algorithm is introduced to cope with changes of small magnitudes. This algorithm allows a change of a fault index to be detected and can be used as a decision system. The resulting fault detection scheme is computationally cheap and can be embedded in the control unit. Simulations and experimental results validate the proposed method in steady state and the performances under non-stationary operating conditions are also investigated.
... Unfortunately two of these poles are generating negative torque, hence the overall performance of the machine is reduced. This harmful effect can be diminished by increasing the fault tolerance of the machine [16]. The dynamic behaviour of the machine and its power converter was studied by means of co-simulation, by coupling together the Flux 2D model of the machine with the Simulink model of the control system and of the power converter. ...
Switched reluctance machines (SRM) arewidely used in safety-critical applications due to theirwell-known inherent fault tolerance abilities. Despiteof this some faults are possible to occur, hence faultdetection circuits can be useful components of theSRM's control system. The first part of the paper is anoverview of the SRM's faults and their detectionsystems. Also the causes and the effects of the mosttypical faults are detailed. In the second part the effectsof the SRM's winding faults are studied by means ofadvanced co-simulation techniques.
In safety-critical systems, faults can cause life losses, environmental degradation, or significant financial losses. In this paper, a segmental stator switched reluctance machine is proposed for such applications. A short overview of its design is given. Its fault tolerance is investigated by dynamic simulations and laboratory tests. It is demonstrated via both methods that the proposed machine is able to have a continuous operation despite five severe winding fault conditions.
