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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...
Different faults in Permanent Magnet Synchronous Machines will cause various and independent changes to the machine magnetic flux distribution, which will cause different changes to the machine parameters and performance. These changes will be reflected in the machine flux linkages, which can be determined from the machine voltages. In this paper, a method is proposed to detect and separate three...
This paper proposes a flexible compensation strategy for parallel-connected doubly fed induction generators (DFIGs) when connected to an unbalanced weak grid. The proposed strategy has two main advantages: 1) the voltage unbalance factor (VUF) at the point of common coupling (PCC) can be continuously controlled, thus the flexible trade-off between the balanced DFIG output current and the balanced...
An FPGA implementation of Model Predictive Direct Current Control (MPDCC) is reported in this paper. A central scheduler enumerates switching sequences and assigns these to several explorer units, which predict the system response and compute their associated cost. The proposed FPGA design is scalable, modular and requires little hardware resources. A five-level active neutral point clamped inverter...
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...
This paper presents a new method of combined electromagnetic levitation and propulsion using a double sided pair of linear induction machines and a simple conductive sheet secondary. If the supply phase angle of one primary is modified with respect to that of the other, a controllable lift force can be developed on the conductive secondary and its load at any velocity or when stationary. Further,...
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...
A flux-switching permanent magnet (FSPM) machine using ferrite magnet is proposed to replace the permanent magnet synchronous motors (PMSMs) in elevator doors. In order to improve both mechanical robustness and manufacturability, bridges around permanent magnet (PM) slots have been adopted in the C-shaped core of an FSPM machine. The optimization of the C-shaped stator is conducted, and its prototype...
The impact of restarting an induction machine, while coasting, is investigated in this paper. When restarting a motor, high peaking currents and torque transients appear. As a result, possible damage to the rotor shaft could occur together with destabilising the power system which could lead to a fluctuating supply voltage levels. This paper investigates the restarting of two different efficiency...
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...
Compared to the three-level neutral point clamped (3L-NPC) inverter, its simplified version, the 3L-SNPC, uses fewer switching devices to achieve a multi-level output. However, it offers fewer voltage vector selections, limiting its usefulness for motor drive applications. This issue is overcome through a proposed direct torque control (DTC) strategy utilizing the concept of virtual voltage vectors...
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 Cadillac CT6 plug-in hybrid electric vehicle (PHEV) power-split transmission architecture utilizes two motors. One is an induction motor type while the other is a permanent magnet AC (PMAC) motor type referred to as motor A and motor B respectively. Bar-wound stator construction is utilized for both motors. Induction motor-A winding is connected in delta and PMAC motor-B winding is connected in...
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...
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