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A high conductivity shield is often used for coating the rotor of solid rotor synchronous machines for reducing the surface eddy current losses due to the armature reaction space and time harmonics and/or tooth ripple. Since the design process for determining the optimal shield thickness can be very complicated and time-consuming, a simple analytical model based on Maxwell's equations was developed...
Fault detection in electric motors operating under non-stationary operating conditions has been gaining importance, due to the fact that motors are used in many applications such as actuators in the aerospace and transportation industries operate under conditions that rapidly vary with time. In recent times, a plethora of new time-frequency distributions have appeared that are inherently suited to...
A small high temperature superconductor (HTS) coil was designed and tested at GE-Global Research Center (GE-GRC) to evaluate the over-current capability for HTS generator rotor. The superconducting rotor coil is a layer-wound racetrack coil using the BSCCO 2223 conductor. Over-current simulation tests have been done to simulate the fault operation condition for generator based on the previous analysis...
This paper is devoted to the diagnosis of rotor faults in closed-loop induction motor drives. Different control strategies are studied, namely the direct torque control and the indirect rotor field oriented control. A detailed analysis of different motor/controller variables enlightens about the behavior of these systems under the presence of rotor faults. Numerous simulation results as well as experimental...
High-frequency current responses of a PM synchronous machine with and without considering the eddy current effects are significantly different. This paper identifies and investigates the eddy current effects on rotor position estimation. Compensation method is developed to improve high-frequency-injection-based sensorless control of a PM synchronous machine at zero and low speeds. The estimation and...
This paper describes a simplified novel method of sensorless detecting excitation position for switched reluctance motor (SRM) drive. The proposed sensorless excitation position is based on the amplified detecting phase current by the short dc pulse voltage according to the rotor position during detecting period. In the proposed sensorless scheme, a phase winding has excitation, detecting and non-excitation...
There is a strong interest in using LEDs for general illumination due to the potential they offer for energy saving, environmental friendliness, new opportunities in lighting design, and control of the intensity, color, and spatial distribution of light. General illumination requires primarily white light that can be obtained by mixing e.g. the light of red, green, and blue LEDs. This enables also...
Ground fault current is very small in ineffectively earthed power systems, and it is difficult to detect the fault line. Traditional fault detection methods based on zero sequence current are difficult to satisfy the requirement of distribution automation (DA). In order to improve it, the grounding fault protection scheme with phase current sampled value difference is presented in this paper. The...
This paper discusses the design of true redundant, N+l parallel voltage regulator module (VRM) system with low droop resistance. Average current mode control and limited gain for voltage compensation is used to achieve droop current sharing between parallel modules without single point failure. Small signal model of the current sharing scheme is derived and experimentally validated. A novel local...
In the transportation field, the empty weight of the vehicle has to be as light as possible in order to have the highest energetic efficiency. For onboard storage electrical systems, DC/DC converters are usually used to control the power flows in the vehicle. This paper focuses on two different DC/DC converter applications: high current/low voltage on the one hand and low current/high voltage on the...
Field oriented control of induction machines is a well-established technology, widely used in applications where high-bandwidth torque control of AC machines is needed. A key parameter in the implementation of the indirect field orientation (IFO) method is the slip gain, the inverse of the rotor time constant, which is used for estimation of the rotor flux angle. A method for estimating the slip gain...
Demanding high power applications, such as medical imaging, fast processors, and pulsed loads are requiring new levels of performance from dc/dc converters. Extremely low ripple voltages, blazing speed and response, all with high efficiency and small size are placing conflicting requirements on the dc/dc converter designer. Conventional design approaches are not able to meet the needs easily, and...
The general trend towards smaller and more economical designs has also reached bearingless slice motor (BSM) systems. Up to now, full-bridge converters have been used in order to independently control the phases of the active magnetic bearing and the drive system. In this paper, a simplified topology based on three half-bridges is proposed to replace two conventional full-bridges. With this, the number...
Ultrasonic motors are a good alternative to electromagnetic motors in medical robotics, since they are electromagnetically compatible. Estimating speed instead of using encoders reduces cost and dimension of the robot on the one hand and increases reliability on the other hand. However, no sensorless speed controller is yet industrialized. Analytical models of the traveling wave ultrasonic motor being...
This paper proposes two PWM strategies and related programming methods for DC-to-three-phase AC voltage-source-inversion and three-phase AC-to-DC voltage-source-rectification respectively. They are based on the general direct space vector modulation approach derived from matrix converter theory, and sharing the same algorithm in calculating vector duty-cycles. The one for DC-AC inversion can accommodate...
This paper intends to compare the many different solutions available to design a busbar interconnection. Starting from a single copper plate and going to multilayer busbars, the influence of the external shape of the sheet, of the number and the nature of holes and apertures are considered. Simulations and measurements are used to determine the stray inductance of the different busbars. Design rules...
This paper presents a family of high power factor electronic ballasts applied to the public lighting system. Flyback, buck-boost, boost or SEPIC converter is employed in the power factor correction stage, integrated to the power control stage through a single active switch. The use of a half-bridge inverter, to supply the lamp, becomes possible through the employment of a flyback converter in the...
This paper presents two optimal control strategies for a grid independent photovoltaic system consisting of a PV collector array, a storage battery, and loads (critical and non-critical loads). The first strategy is based on action dependent heuristic dynamic programming (ADHDP), a model-free adaptive critic design (ACD) technique which optimizes the control performance based on a utility function...
A novel and efficacious constant power control strategy of electronic ballast for HID lamp is proposed in this paper. The constant power control gear mainly consists of an 8-bit micro-controller and a PWM control IC. The micro-controller samples the lamp voltage, and calculates an appropriate value of lamp current. The PWM IC controls the lamp current equal to the calculated current value. Thus constant...
Among the two main possibilities of connecting electronic igniters (series and parallel connection), the series one is widely used. In steady state operation, the series igniter should behave like a short circuit, in order not to affect the operation of the lamp-ballast system. The main disadvantage of this configuration is the high value of the secondary winding of the step-up transformer used for...
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