This paper looks at a novel optimisation approach to the design of surface mounted permanent magnet (SMPM) machines with self-sensing capabilities. A methodology will be presented which will look at the use of genetic algorithms (GA) to contemporarily maximise the output torque and the self sensing properties of such machines. A GA optimisation environment has been grafted with a finite element analysis (FEA) environment to enable the designer to account for both geometrical and saturation saliencies for an effective determination of the machine's self sensing characteristics. Satisfactory results were obtained in terms of torque maximization and self sensing capability. In addition sensitivity of the major geometrical parameters of the machine will be discussed in terms torque density and the self-sensing.
In this paper there are presented the experimental results for the average power three-phase synchronous generator, connected successively on a controlled bridge rectifier, also on a half-controlled one. There are taken into account the electrical quantities to the generator windings terminals, the damping winding bars currents and the field in different portions of the magnetic circuit. The results are close to the ones obtained by computation and they allow the proper dimensioning of the generator elements.
In this paper three voltage control, strategies for three-phase ac voltage regulator have been studied. These strategies depend on varying the stator ac voltage to control the speed of three-phase induction motor. These strategies are phase angle control (PAC), extinction angle control (EAC), and modified phase angle control (MPAC). The first control strategy is carried out using three back-to-back thyristors connected in series with motor terminals. The other two techniques are used with converter having six bidirectional switches. Performance evaluation of the motor under these switching techniques is shown. Simulation of the system is carried out by PSIM computer program. The simulation results show stable operation for wide range of speed control. The level of harmonics in the supply currents and power factor have been also evaluated for different control strategies.
This paper presents a high torque mass ratio electromagnetic actuator which works with two differents coupling of the air gap magnetic field. The first one is a polar coupling as for the conventional synchronous machines and the secondth is tooth coupling as for the Vernier machines.
Sliding mode control and fuzzy logic control have been combined together in order to optimize the performance given by conventional sliding mode control; especially against the effect causes by the chattering phenomenon. One approach taken by many researchers is to use fuzzy logic to smooth the chattering in sliding mode control. In this paper, a novel direction to design the fuzzy sliding controllers is proposed. In fact, the control design is based on the fuzzy model of an induction motor using the approach of Ben-Ghalia. The aim of the proposed modelling approach is to provide a fuzzy set based representation of the cascade sliding mode control of an induction motor fed by PWM voltage source inverter, which operates in a fixed reference frame. For this purpose, a new decoupled and reduced model is first proposed. Then, a set of simple surfaces and associated control laws are synthesised. A piecewise smooth control function with a threshold is adopted. However, the magnitude of this function depends closely on the upper bound of uncertainties, which include parameter variations and external disturbances. This bound is difficult to obtain prior to motor operation. To solve this problem, a fuzzy modelling approach is presented to improve the design and tuning of a fuzzy logic controller using variable structure control theory. The fuzzy controller, is designed in order to improve the control performances and to reduce the control energy and the chattering phenomenon. Simulation results reveal some very interesting features.
The behavior of brushless DC motor with its drive and converter is described and highlights the requirements for accurate simulation at full-load operation. Results obtained with two commercial software packages are presented. Tricks for models developed with both softwares are provided in order to obtain good results. The simulation results are compared with measurements at no-load and full-load operations made on a prototype.
In this paper, we propose a grid-connected photovoltaic power system including batteries in order to provide prescribed reactive and real powers to the grid. According to the stochastic nature of the photovoltaic power, the main feature of the proposed system is to erase power fluctuations by designing a dedicated local control system. With batteries, the whole system is able to smooth the PV power and provides a power reference, which is required by the grid operator. Therefore, the photovoltaic systems can be integrated more efficiently in the grid system and participate to the grid stability. An equivalent continuous dynamic model and control design of the studied power system are proposed in this paper. Simulation results are given to validate the feasibility of the proposed system.
Following a series of articles presenting the modelling and simulation of an autonomous variable- speed hydropower station feeding an isolated load or connected to a power grid ([2], [3]), this paper is aiming to validate on the test bench the solutions proposed earlier. The studied system is composed of a doubly-fed induction generator (DFIG) linked mechanically and electrically (through back-to-back power electronic converters in the rotor circuit) to a permanent-magnet synchronous machine (PMSM) which may recover or supply the slip power. One of the advantages related to this system is that the PMSM and the power converters are designed for only about 25% of the plant nominal power.
Throughout this paper, we are going to use two different methods for the optimization of a shape coefficient Sc for a linear tubular step actuator range, allowing to maximize the trust force by Joule losses ratio. The first method is based on analytical computation and the second one is based on reluctance network modelling. These two methods converge to the same result which is validated by finite element simulations.
This paper presents a new and novel technique for speed control of a brushed DC motor without employing any direct shaft transducer in its feedback mechanism. This method uses the current/voltage variation produced on the motor main input power lines as the brushes move from collector blade to the next. The frequency of variation is proportional to the motor speed and the rotor position can also be detected by monitoring the changes for each collector blade. The performance of the motor torque speed characteristic using this system as its feedback has been evaluated through laboratory testing. This configuration is very suitable for harsh environment and places with not enough space for the motor with discrete sensors.
This paper presents an approach to develop a simple reduced speed observer for permanent magnet synchronous generator (PMSG) in wind energy conversion system (WECS). The speed and rotor position estimation of the PMSG are obtained by only measuring phase voltage and current. Maximum wind energy extraction is achieved by running the wind turbine generator in variable-speed mode. The rotor speed is allowed to vary in sympathy with the wind speed by maintaining the tip speed ratio to the value that maximizes aerodynamic efficiency. Advantages of this mechanical sensorless control strategy for maximum power estimation are demonstrated by digital simulation of the WECS.
The paper deals with anisotropic PM brushless motors used in railways traction drives. A control algorithm is presented for optimizing performances in a wide speed range. Starting from the assigned torque-speed traction characteristic and taking into account the limit values of armature current and voltage and of air-gap flux magnitude, the expressions of reference values for the current control are found in the different operating regions. Particular attention is devoted to the flux weakening region and to conditions to avoid saturated operations. In order to show the validity of the proposed control algorithm numerical investigation are carried out with reference to some significant operations of a real light-rail traction drive.
The stator current and electromagnetic torque transients of induction motor have been investigated in this paper, when the motor is transferred to uninterruptible power supply (UPS). The motor is directly fed by the infinite bus before the power outage, then it is transferred to the UPS system, which consists of two cascaded 3-phase pulse width modulated converters. Both converters are controlled by a single fixed-point digital signal processor (DSP). The computer simulation results of the UPS and motor are obtained from Matlab Simulink models and these results are compared to the experimental ones.
One of the most important drawbacks of the three phase five-level NPC (Neutral Point Clamped) source voltage inverters(VSI) is the Neutral Point balance. As consequence, the capacitor voltages of the input DC voltage of the VSI are not equal. There are different ways to cope with this problem. In this paper, a simple solution that solves this balance is given. It is based on using of four three phase PWM voltage source rectifier with four clamping bridge to stabilize these Dc voltages. So, the authors propose to study the cascade constituted by four three phase PWM voltage source rectifiers-clamping bridge-filter-five-level NPC VSI-Induction machine. In the first part, we present a topology of five-level NCP VSI, and then we propose a model of this converter and an algebraic PWM strategy for the control. The second part presents the topology and the controlled model of three phase voltage source rectifier. We develop, also a PWM strategy to control this converter. In the third part, we study a high voltage cascade: Four PWM voltage source rectifiers-filter-five-level NPC VSI - Induction machine. In the last part of this paper, the authors study the stability problem of the input DC voltages of the five-level NPC VSI. As application, we study the performances drive of the three phase induction machine fed by this cascade. This drive system can find applications in great power and high voltage fields as electrical traction.
In this paper, a new method for sensorless vector control of permanent magnet synchronous motor (PMSM) using artificial neural network (ANN) observer is developed. This method based on determination of rotor position and thereby speeds by ANN observers. The rotor position angle and rotating speed are estimated by evaluating the instantaneous values of stator voltages and currents. The proposed method was implemented in MATLAB/Simulink software package program. The obtained results are in acceptable error limits for a wide speed range.
The paper proposes a closed-loop modified carrier- based PWM modulation technique for a Z-source inverter, in order to maintain a desired average DC voltage value after the boost section. Extended digital simulations will be presented to demonstrate the features of this control method.
Energy-retaining snubbers of a current-regulated power supply for an AC arc welding machine are proposed in this paper. Although a second output inductor is added, a current-steering diode connected across the output choke keeps the inductor current continuous and retains the energy during the commutation period. Thus no lossy RC snubber is required and no voltage spike is produced. The stored energy can be released in the next energy transfer cycle to reduce the commutation time. Satisfactory experimental results on a 100-A AC arc welding machine are recorded to validate the effectiveness of the presented scheme.
In this paper, a neural network based rotor position control and speed estimation method for permanent magnet synchronous motor (PMSM) is proposed. The proposed method has three recurrent neural networks. They are used for estimating stator current, rotor speed, and rotor position angle. Each of them is trained in two steps: off-line training for learning dynamic of PMSM and on-line training for realizing parameter adaptation of PMSM. Sensorless control of the permanent magnet synchronous motor using neural networks is simulated in Matlab/Simulink.
The adoption of fuel cells for industrial applications, transportations and home power generation has widely increased during recent years. The performance evaluation of a fuel cell system requires both static and dynamic model, especially for the automotive applications which involve step variations of electric load. Besides, current step variations abruptly change the fuel cell voltage causing a non-linear behavior (under-voltages). In this case, a parallel supercapacitor becomes an important element to provide energy during transients. Fuel cell dynamic models presented in literature adopt chemical-physic-electrical parameters that are not usually provided by factories. In this paper, we deal with the implementation of dynamic fuel cell model during step current transients from the electrical point of view [1]. The FC model is used to compute the minimum capacitance of the supercapacitor needed to obtain gradual variations of fuel cell terminal voltage from initial steady state to final steady state values.
In this paper, the analysis of self excited induction generator (SEIG) connected to utility grid is studied. We simulated the reconnection of the SIEG to the utility grid after a short perturbation. A mathematical model of the induction generator using Park's model, where taking account the saturation of the magnetizing flux is developed. The experimental results of transient currents are approached by simulation, because the initial conditions are not the same ones in practice.
