Dan-Gabriel Stanescu

Induction versus interior permanent magnet synchronous motors for positioning systems using direct flux vector control

The development of a control strategy suitable for Permanent Magnet (PM) and Induction Motor (IM) drives is considered. The proposed scheme is based on the Direct Flux Vector Control (DFVC) method, adapted for positioning systems (over azimuth and elevation). A comparative study of IM and Interior PM motors performances is presented.

About the experimental results of an electric driving system based on asynchronous motor and PWM converter

The paper deals with special features related to the a.c. electric driving system of a trolley-bus. One presents the driving system consisting of an asynchronous motor and inverter and some aspects regarding the PWM inverter control. The tests over the manufactured asynchronous motor were performed at a frequency equal to 50 Hz (for the rated speed) and a frequency equal to 106.6 Hz corresponding to a synchronous speed equal to 3200 rpm. The inverter was separately tested, before its inclusion in the driving system and some of the tests results presented (heating tests for the main components, the behavior at the discontinuous variation of line voltage, a.o.). Some tests concerning the behavior of the entire system at forward and backward running regimes are also presented.

Performance comparison between active and passive power filters for a static excitation system in a power generator group: A MATLAB/Simulink approach

This paper presents a comparison of the performances related to compensation and transient response of active and passive power filters when operation relies on distorted mains voltages. MATLAB/Simulink models are used. Measurements acquired with a dedicated data acquisition system provided the parameters required by the real system simulation, namely a static excitation system of a power generator group. The simulated system consists of a transformer which feeds a controlled rectifier bridge. Replacing the old auxiliary excitation generator raises two important problems: the line voltage notching due to thyristors switching and additional line current distortion. Theoretical aspects of line notching and passive and active solutions for compensation and their limitations are also discussed.

The designing of a positioning system for PV modules used to supply a stand alone consumer

The paper is related to aspects concerning the realization of a positioning system for PV modules. One describes the design of the main parts of the system. The PV modules are used to supply a stand alone consumer. The systems efficiency is improved if it is properly orientated with respect to the highest intensity of the light. The proposed positioning system is an automated two axes system which orientates the PV modules from East to West and from North to South respectively. The drive system used to orientate the PV modules contains two H-bridges and two DC motors. Finally, the testing of the entire positioning system based on a dedicated software is presented.

On the efficiency of asynchronous motors used in urban transportation systems

The paper presents a drive system consisting of an asynchronous traction motor and inverter used for trolley-buses. An analysis is made with respect to the exploiting of a traction drive system using the classic design (with d.c. motors), underlining the disadvantages of this type of driving The control of driving systems in a.c. is currently performed using modern techniques for vectorial control, allowing the increasing of their efficiency. A good practice is to start by analysing the feasibility of simple control strategies, requiring a small number of parameters. A series of simulations were made in order to analyze the motors behaviour in steady - state regime, with a simple variable speed control method. In the end possible explanations for the driving system efficiency reducing are discussed.

A hybrid low-power system used to supply a local consumer

The paper is focused on the hybrid (photovoltaic, battery and distribution network) system. The proposed system is used to supply a low power consumer when the distribution network fails or in case of a low light intensity. The system operates under normal supply by the local distribution network. In case of failure, the system automatically switches to local consumers supply by a photovoltaic system (in sunny days) or by battery (during night-time and in days with low light intensity). One describes the main parts of this system. Finally, the test results of the proposed system with resistive and resistive-inductive loads are presented. A harmonic analysis of the current and voltage absorbed by the loads was also performed.

An efficient method for flux weakening control of an induction motor drive system

The paper presents a speed-sensorless induction motor drive system operated into deep flux weakening region. An efficient direct control method based on the stator flux control is detailed. The speed-sensorless proposed algorithm is based on the induction motors mathematic model and is suitable for low cost industrial applications. Simulations and experimental results based on this algorithm are also presented. The experimental tests were performed based on a dSPACE DS 1103 platform controlling an inverter fed 4 kW induction motor.

Indirect vector control of induction motors drive systems considering the iron loss resistance

The paper deals with a modality to perform indirect vector control while considering the iron loss resistance. The control algorithm was conceived starting from the induction motors mathematic model. Its implementation improves the drive system efficiency. Two cases are presented. In both of them the iron loss resistance is considered, but the first one considers the same value for the rotor time constant, whilst for the second one the rotor time constant is modified. A comparative analysis is made for the mechanic torque, when the speed is lower than the rated value. Through this control algorithm a reduction of the difference between estimated and measured torques while considering the iron loss resistance and a variation of the rotor time constant were realized. dSPACE DS 1104 was used to perform the experimental tests. In the end, tests were performed considering the variation of the magnetizing inductance in the range of speeds higher than the rated one.

New trends in the designing and realization of electric equipment used at urban transportation systems operating in a.c. regimes

The paper presents some results yielded from the research work concerning a prototype trolleybus with asynchronous motor drive system made from an PWM inverter and an asynchronous motor. Simulations on the driving system behaviour and experimental data concerning the prototype are also presented.