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Progresses obtained in command and power electronics have increased the technical and economic performances of brushless direct current motors. Consequently, the problem of optimum design and operation of these motors, frequently used for driving small vehicles, is a very present one. Studies presented in literature show that high oscillations of torque occur in these motors in a complete rotation...
In this paper there is detailed the asynchronous operation caused by an important overload, of a synchronous motor. There are mentioned the currents of all the windings, main flux, electromagnetic torque, electrical angular speeds of the rotating field and of the rotor which define the amplitudes of the electrical, magnetic and mechanical stresses. The effect of the damping windings resistance in...
This paper presents a practical way of identifying the defective diodes of an alternator. For this purpose are presented a series of experimental tests of some car alternators. There are detailed the automatic voltage control by modifying the excitation current of the generator and different waveforms of the voltage obtained when one or more rectifier diodes are damaged. The paper ends with conclusions...
This paper emphasizes technical and economic parameters at direct-on-line starting of low power asynchronous motors. There are presented a lot of simulations and there are carried out experimental tests, in order to establish deviations which occur between the two methods. On the basis of the mathematical model presented, it is also possible to study other dynamic states: variation of voltage, of...
Advance in high-tech industries is due to evolution, respectively performance of electrical machines. Worldwide, designers are concerned to find answers to current questions such as: performance growth of asynchronous motors, reduce manufacturing and operating costs by adopting solution in line with global optimization approaches. Condition imposed to asynchronous motor design is limited startup current...
In this paper there is analyzed the dynamic behavior of a reluctance synchronous motor with continuous rotation in case of supply to a vector-control converter. In this purpose a simulation program has been conceived; it is based on the motor equations written in the two-axis theory. The model used is an original form, with combined variables. It can be used for any type of synchronous machine. The...
This study considered different constructive variants of brushless direct current motors which have the same rated data, constructive dimensions and electromagnetic stresses. The motors differ by their number of poles and slots. The analysis aimed at torque value, low torque oscillations and energetic efficiency. There has been identified the optimum constructive variant which has 2p=40 poles and...
In this paper there is established the hybrid mathematical model of permanent-magnet synchronous machine. This is a useful instrument in the design stage, for identifying the effect of parameters upon the behaviour in dynamic processes and for completing the electromagnetic and constructive solution.
In this paper there is presented a method for analyzing dynamic regimes of asynchronous machines, by using the equations with saturation, which have the stator current and the rotor flux as state variables. In the first part, this mathematical model is detailed. There are presented below a series of simulations obtained by means of some Matlab programs carried out starting from this model. The simulations...
Interest paid lately to brushless direct current motors made the researches regarding the optimum design and construction of these motors to be very present. The study carried out, by the simulations we presented, shows that these motors have high torque oscillations in a complete rotation. There are identified the slots which create high torques, respectively low torques, in a complete rotation,...
In this paper there are presented the constructive variants of reluctance synchronous motors. A special attention is paid to the main features, their advantages and drawbacks. In order to confirm this study there have been carried out experimental tests with a flux-barrier motor. There are presented the circuit we used and the main steady state characteristics we obtained. The paper ends with conclusions...
The electromechanical conversion is a very important aspect in the conversion process of the energy; it is carried out by means of the electrical machines used in all areas of the human activity. By using the electronic computer in the electrical machines design, there can be obtained some better operation characteristics, there can be decreased the losses of electrical energy and increased the power...
This paper presents a series of dynamic regimes specific to the operation of permanent-magnet synchronous motors used for electrical motor-scooters. On this purpose, there is presented the mathematical model of the motor. By means of this model, there has been carried out a programs package of simulation (in Matlab); a part of these simulations are presented in this paper. There have been considered...
This paper presents details regarding a possibility of modelling (in Simulink) and monitoring a driving system with reluctance synchronous motor (RSM) with vector control. In this purpose there are presented the mathematical model of the motor, the structure of the driving system and the model of the converter. It is insisted to detail the blocks of coordinates transformations and the blocks of phase...
Optimal design of an electrical machine is associated with an investigation of the operation conditions of the machine, of the environment and of the driving system of the equipment. The interest for person transporting two-wheel vehicles driven by brushless direct current motors has increased lately; consequently, new researches regarding design and optimal construction of these motors are very present...
The site of e-learning www.e-lee.net has been carried out by the collaboration of four universities from Belgium, France, Portugal and Romania, along a period of three years. This paper makes a general presentation of this site, with emphasis on an application dedicated to reluctance synchronous motor. There are presented the construction, operation principle, equations and a few characteristics in...
In this paper there are presented a series of dynamic regimes obtained for the case when some disturbances occur during the operation of a reluctance synchronous motor operation: the decrease of the sinusoidal supply voltage value and the supply by a non-sinusoidal source of voltage (indirect voltage and frequency converter voltage source with PWM command and voltage inverter with pre-computed moments...
The objectives followed in the frame of this paper are to approach comparatively, from the view point of the operation performances and exploitation costs obtained for two types of motors (asynchronous motor and permanent-magnet synchronous motor), by means of some specialized computation soft-wares. Because of the drawbacks of asynchronous motors (high shock of starting current, relatively low power...
The utilization of low power permanent magnet synchronous motors for driving electromechanical equipments means a substantial decrease of the exploitation expenses, because these motors have good efficiency and power factor. The optimal design of these motors aims at searching and choosing that machine which to the criterion minimum total cost and to certain restrictive correspond conditions imposed...
Very important are the energy analyses at the rheostatic starting of the existing wound rotor three-phase asynchronous motors, used for driving the long belt-type carriers, which have a difficult and long-duration starting. A factory producing static converters proposes to the customer a modernization of the starting by using a single-phase rheostat and a three-phase bridge in the rotor. That is why,...
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