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Hybrid Excitation Synchronous Machines allow broad flux regulation, and therefore a very wide Constant Power Speed Range. Literature shows that it is possible to build them both with a Single-Axis and with a Bi-Axial excitation. This paper presents a unified approach for the analysis, comparison and performance prediction of the two structures. Finite element simulation and experimental tests are...
Three phase ac drives using a dc link typically feature a significant amount of dc energy storage to maintain a stiff dc bus. This paper examines the concept of reducing the size of the dc link capacitor dramatically, to store just enough energy to provide one high frequency switching cycle of output power. The dc bus is no longer stiff and hence the classical sinusoidal pulse width modulation cannot...
Several methods have been proposed to measure the speed of an induction machine without the need for external speed transducers. These sensorless methods typically use observers, require injected signals, or are dependent on the detecting a specific harmonic. This paper investigates using neural networks to identify the speed of a machine using a range of harmonics without specific knowledge of machine...
Thermal monitoring is a common feature in most of electric machine drives since thermal overloading is one of the most common causes of motor failures. Contact-type sensors are normally used to measure the stator temperature in electric machines. However, use of this type of sensor is not advisable in the rotor as it requires cabling to a rotating part or the use of a wireless transmission system...
In this paper, a special control solution called “Virtual Voltage Source” is developed for no-load tests of induction machines. This concept is applied to a 2×27 MVA high-power machine test bench, where the test bench is requested to precisely characterize e.g. 3 MW machines at no-load currents. The developed Virtual Voltage Source thoroughly solves the stability issue of induction machines at low...
Transverse flux machines can be a torque dense solution for applications requiring a relatively low speed such as electrically assisted bicycles or scooters. Common drawbacks include a high torque ripple caused by a high cogging torque and high back electromotive force harmonics. Cogging torque is of particular importance as it can be felt even when the system is disengaged and the bicycle is being...
High-speed machines require structurally robust rotor to withstand high centrifugal forces. Flux switching permanent magnet (FSPM) machines are ideal for high speeds since they have a simple and robust rotor structure. They also utilize permanent magnet (PM) in the stator enabling them to achieve high power density. It is desirable to keep the operating frequency minimized to reduce core losses and...
This paper presents a method of reducing the cogging torque of transverse flux machines by shaping the poles of the rotor. A number of different techniques are presented and simulated. These simulations are verified by the construction of a number of rotors from which measured results have been obtained. Further to this, the rotors are applied to machines with different cogging torque reduction techniques...
This paper proposes a fast and generalized multi-objective design and optimization method for the Switched Reluctance Machines (SRM). An analytical design model for SRMs with any feasible stator and rotor slot combinations is firstly developed, which can accurately evaluate a SRM design much faster than the prevalent finite element analysis (FEA) method. In addition, a novel method for multi-objective...
This paper proposes an active filter (AF) enabled power architecture to harness oscillating power from wave energy converter (WEC). The proposed power architecture consisting of a diode rectifier and a dc-dc converter along with the partially-rated active filter, is cost-effective compared to conventional fully-rated power converter in generating oscillating power. The architecture is suitable to...
The direct model predictive control (MPC) problem for linear systems with integer inputs, such as many power electronic systems, can be formulated as an integer least-squares (ILS) optimization problem. However, solving this problem when state and/or output constraints are explicitly included is challenging. In this paper, a method that allows to effectively use the sphere decoder — even in the presence...
This paper introduces a new method to stabilize synchronous reluctance motors (SynRMs) driven by efficiency optimized V/f control utilizing optimized flux. Efficiency optimized V/f driven SynRMs are prone to instabilities. Specifically, it becomes unstable for either fast ramp acceleration or large load disturbances. For example, in an efficiency optimized V/f control scheme, flux is reduced under...
Salient pole wound field synchronous machines (WFSMs) share similar torque characteristics as permanent magnet (PM) machines, but are free of permanent magnet material since a wound rotor winding instead generates the required field flux. In addition to cost advantages, the rotor field flux is readily varied making these machines attractive for traction and generator applications. This paper introduces...
This paper presents an approach to implement the universal flying restart for an induction machine using a frequency search algorithm that determines the rotor speed so that the correct frequency and voltage can be applied to minimize the inrush current during the restart. This method only uses the measured phase current and the motor nameplate parameters, thus making it ideal for use with scalar-controlled...
This paper considers the possibility of adopting a conical shaped motor for Green Taxiing (GT) application. This topology of motor has been selected in order to obviate the presence of external declutching system (i.e. mechanical or electromagnetic clutch) interposed between the electric actuator and the wheel. An axial force contributes to move the rotor inside-out of the stator (principle of sliding-rotor)...
Motor current signature analysis (MCSA) has recently become widespread in industry for on-line detection of rotor cage faults in induction motors for preventing forced outages. Although it can provide low cost, remote monitoring of rotor faults, cases of false indications have been reported, where the causes of some false indications are still unknown. It is shown for the first time in this work that...
Doubly fed induction generators are presently used in the large majority of high power wind turbine applications. The current doubly-fed induction generator technology specifies that the turbine operates sub-synchronously to follow the desired power vs. wind speed profile and to operate super-synchronously only during brief periods where wind gusts exceed the nominal maximum value of thrust. This...
This paper proposes a control scheme for the wide operation range of an induction generator (IG) with a Vienna rectifier. A Vienna rectifier has the limited operation range because the sign of the current should be the same as that of the voltage in the normal operation. For this reason, the power factor of a Vienna rectifier is also limited. In the IG, the d-axis stator current is necessary for the...
Electromagnetic acoustic noise from electrical machines has increasingly become an area of attention for both academia and industry. In electric propulsion systems, this is a main contributor to the total acoustic noise and it is usually perceived as annoying due to its tonal appearance. This paper presents an alternative rotor design for a permanent magnet synchronous machine with the objective to...
This paper proposes a rotor tooth shaping method to reduce the cogging torque of an axial flux-switching permanent magnet machine. The rotor tooth is shaped in different configurations, including constant, trapezoidal, asymmetrical, extended, and square shapes. 3-D finite element analysis is performed to compare the proposed shapes of rotor tooth. Peak-to-peak cogging torque, fundamental flux linkage,...
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