Top PDF Rotor Speed Estimation Method Used in Dynamic Control of the Induction Motor

From this paper emerges that the algorithm proposed by me where the rotor speed is calculated directly by the robust adaptive reduced order Gopinath flux observer, proved to be efficient both in transient regime and in indirect field oriented control system with three-phase induction motor. For a more stable flux observer poles were placed on the negative real axis, thus obtaining relative simple calculations in real time. Also, the coefficient K can control the correction weight generated by the corrector and applied to the simulator, from the flux observer structure. Thus, for a well chosen coefficient K, the simulation results confirmed that the initial estimation error reduces rapidly and the estimated value converges to the actual one.

induction motor drives where the mechanical speed of the rotor is generally different from the speed of the revolving magnetic field. The advantages of speed sensorless induction motor drives are reduced hardware complexity and lower cost, reduced size of the drive motor, better immunity, elimination of the sensor cable, increased reliability and less maintenance requirements. The induction motor is however relatively difficult to control compared to other types of electrical motors. For high performance control, field oriented control is the most widely used control strategy. This strategy requires information of the flux in motor; however the voltage and current model observers are normally used to obtain this information.

As illustrated in Fig. 1, the hardware design is classified into six main stages. Firstly, sound signal is to be changed to an electrical signal. SM58 SHURE dynamic microphone is used here to produce an electrical signal from the sound signal vibration. The electrical output signal from this microphone is to be amplified using a sound amplifier with a high slew rate. LM386 (Low Voltage Audio Power Amplifier) was used here to give the required amplification. The amplification circuit is shown in Fig. 2. The input was applied to the LM386 through 10K variable resistor so as to meet the operating point of the internal transistors. Pin.1 was connected to pin.8 through 10µF capacitor to increase the gain to the maximum .pin.7 was connected to the ground through 220 µF as a bypass capacitor to bypass unwanted signals to the ground. After amplification the signal was converted to DC using four diodes as a full wave rectifier as shown in Fig. 3. In order to overcome the problem of rippling, a parallel combination of a capacitor and a resistor was used. The microcontroller (ATMEGA16) has three functions as shown in Fig. 4. The Pulse Width Modulation (PWM) that controls the rotational speed of the motor will be generated from the microcontroller.

on of speed, which can further improve performance of the drive. The perfor- mance will further improve with increase in sampling frequency. But there are some limitations. It has been observed that the controller is suited up to speeds of ±700 r.p.m. Better design of the fuzzy controller with different membership functions and tuning of PID parameters will improve performance of the motor control even for lower speeds. However, presently the new control method has been discussed and further improvement has been kept for future work. The pre- sent work highlights capability of the new method for bi-directional control of induction motor with reduced rule base. Introduction of the final state selector helped to reduce the rule base to 36 rules as compared to 72 rules for direct tor- que control. Thus the advantage of the proposed technique is to improve real ti- me processing. Moreover, it presents a new control technique of induction motor.

very low value of the 2 nd column of the matrix R = A A and this means that this problem is ill- T conditioned ( K problem): this results in a flat error surface along the 2 K direction [26]. 2 Numerical scaling does not help in solving this problem. In [24] this problem was attacked by devising an estimation method which considers the constraint (8) indirectly and has good tracking capabilities: in particular in transient conditions all four electrical parameters can be retrieved, since the data matrix is full rank, while in sinusoidal steady-state only two K -parameters can be computed, since the data matrix has rank 2. Consequently only one electrical parameter can be obtained in sinusoidal steady-state, in particular the rotor time constant for vector-controlled induction motor drives and the stator resistance for direct-torque controlled induction motor drives. In these works a selection algorithm has been then developed for choosing the parameters to be estimated in all working conditions.

Abstract — Direct torque control (DTC) is a new method of induction motor control. The key issue of the DTC is the strategy of selecting proper stator voltage vectors to force stator flux and developed torque within a prescribed band. Due to the nature of hysteresis control adopted in DTC, there is no difference in control action between a larger torque error and a small one. It is better to divide the torque error into different intervals and give different control voltages for each of them. To deal with this issue a fuzzy controller has been introduced. But, because the number of rules is too high some problems arise and the speed of fuzzy reasoning will be affected. In this paper, a comparison between a new fuzzy direct-torque control (DTFC) with space vector modulation (SVM) is made. The principle and a tuning procedure of the fuzzy direct torque control scheme are discussed. The simulation results, which illustrate the performance of the proposed control scheme in comparison with the fuzzy hysteresis connected of DTC scheme are given.

In recent years, marked improvement has been achieved in the design and manufacture of stator windings [1]. Motors driven by solid-state inverters undergo severe voltage stresses due to rapid switch-on and switch-off of semiconductor switches. Also, induction motors are required to operate in highly corrosive and dusty environments. Requirements such as these have required the development of vastly improved insulation material and treatment processes. However, cage rotor design and manufacturing have undergone little change. As a result, rotor failures now account for a large percentage of total induction motor failures [1], [2]. Cage rotors are basically of two types: cast and fabricated. Previously, cast rotors were only used in small machines. However, with the advent of cast ducted rotors, casting technology can be used even for rotors of machines in the range of 3000 kW. Fabricated rotors are generally found in larger or special-application machines. Cast rotors, although more rugged than the fabricated type, can almost never be repaired once faults like cracked or broken rotor bars develop in them. The reasons for rotor bar and end-ring breakage are many. They can be caused by thermal stresses due to thermal overload and unbalance, hot spots or excessive losses, sparking (mainly fabricated rotors), magnetic stresses caused by electromagnetic forces, unbalanced magnetic pull, electromagnetic noise and vibration, residual stresses due to manufacturing problems, dynamic stresses arising from shaft torques, centrifugal forces and cyclic stresses, environmental stresses caused, for example, by contamination and abrasion of rotor material due to chemicals or moisture, mechanical stresses due to loose laminations, fatigued parts, bearing failure, etc.

“Brushless DC motor”[1] is used to identify the combination of AC machine, solid state inverter and rotor position sensor that results in a drive system having a linear torque – speed characteristic as in an conventional DC machine High efficiency due to reduced losses, low maintenance and low rotor inertia of the BLDC motor have increased the demand of BLDC motors in high power servo [4] and robotic applications. The invention of modern solid state devices like MOSFET, IGBT and high energy have widely enhanced the applications of BLDC motors in variable speed drives. In this work, a digital controller is developed for this drive which uses minimum number of components employing a recently introduced DSP (TMS320F240) by Texas Instruments (TI) for power electronics applications 7 . First the control scheme of the drive is analyzed and its simulated results are validated with test results obtained from developed digital controller

Nevertheless, this approach requires an important computation time, which can be a serious handicap for its implementation in real time. However, since the frequency signature of a fault is located on a known frequency band [15], then the proposed solution in this paper consists of the decrease of the computation time and the used memory space by applying the processing only on the frequency band where the signature of the fault is likely to appear. To highlight the contribution merits of this new approach in the detection and the monitoring of rotor faults severity, several experimental tests are conducted on an induction motor by analysing the stator current signal in the steady-state and without varying the load or speed of the motor.

Abstract: Two structures of speed estimator for AC drive system are developed in this paper. The mathematical models and the simulation results, via numerical simulation, are presented. The utility of the estimator is important for the speed control or for the advanced control synthesis such as optimal vector control of induction motor drives. Besides of speed estimation objective, the proposed method increases the robustness of estimators to measurement signal noises.

The main objective of this paper is to control the speed of an induction motor by using seven level diode clamped multilevel inverter and improve the high quality sinusoidal output voltage with reduced harmonics. The presented scheme for diode clamped multilevel inverter is sine carrier Pulse Width Modulation control. An open loop speed control can be achieved by using V/ƒ method. This method can be implemented by changing the supply voltage and frequency applied to the three phase induction motor at constant ratio. The presented system is an effective replacement for the conventional method which has high switching losses, its result ends in a poor drive performance. The simulation result portrays the effective control in the motor speed and an enhanced drive performance through reduction in total harmonic distortion (THD). The effectiveness of the system is verified through simulation using PSIM6.1 Simulink package.

Direct current (DC) motors have been widely used in many industrial applications such as electric vehicles, steel rolling mills, electric cranes, and robotic manipulators due to precise, wide, simple, and continuous control characteristics. Traditionally rheostatic armature control method was widely used for the speed control of low power dc motors. However the controllability, cheapness, higher efficiency, and higher current carrying capabilities of static power converters brought a major change in the performance of electrical drives. The desired torque-speed characteristics could be achieved by the use of conventional proportional- integral-derivative (PID) controllers. As PID controllers require exact mathematical modeling, the performance of the system is questionable if there is parameter variation. In recent years neural network controllers (NNC) were effectively introduced to improve the performance of nonlinear systems. The application of NNC is very promising in system identification and control due to learning ability, massive parallelism, fast adaptation, inherent approximation capability, and high degree of tolerance.

Fig. 15 depicts the starting current during the first 75ms since the machine starts. It's obvious that the machine under sensorless mode takes a rather long time to accelerate until the ZCP signal is caught for the purpose of stability. Before the commutation moment, the current rises slowly in lad- der-like shape under a lower voltage on account of the limit of sampling precision. After catching the ZCP signal, the current surges to its peak and the motor starts a high-speed BEMF-based commutation mode.

This paper proposed a advance control theory applied with an ANN model on a induction motor. The proposed scheme requires the information of the motor load torque and speed and generate the optimum value of voltage and frequency. The ANN model is configured and trained with some input output pattern. The ANN model is used is a two layer feed forward network, first layer is a tan-sigmoidal layer and have 8 neurons and another is of linear neuron. Computer matlab program is developed to generate the required pattern for training. The trained network was validated by simulation using Matlab/Simulink. In the simulation of induction motor drive indirect vector control strategy is used. The proposed technique is easily implemented on induction motor. The validity of the proposed control technique has been established both in simulation and experiment at different operating conditions. There is a close agreement between simulation and experimental results and shows the dynamic behavior of the system.

The vector control algorithm is based on two fundamental ideas. The first is the flux and torque producing currents [5]. An induction motor can be modelled most simply (and controlled most simply) using two quadrature currents rather than the familiar three phase currents actually applied to the motor. These two currents called direct (id) and quadrature (iq) are responsible for producing flux and torque respectively in the motor. By definition, the Iq current is in phase with the stator flux, and Id is at right angles. Of course, the actual voltages applied to the motor and the resulting currents are in the familiar three-phase system. The move between a stationary reference frame and a reference frame, which is rotating synchronous with the stator flux, becomes then the problem. This leads to the second fundamental idea behind vector control. The second fundamental idea is that of reference frames. The idea of a reference frame is to transform a quantity that is sinusoidal in one reference frame, to a constant value in a reference frame, which is rotating at the same frequency. Once a sinusoidal quantity is transformed to a constant value by careful choice of reference frame, it becomes possible to control that quantity with traditional proportional integral (PI) controllers.

where the parameters of the equivalent circuit are evalu- ated from the experimental DC, locked rotor, and no-load tests [19]. An optical incremental encoder (SUMTAK Corpo- ration, type LDA-001-1000 CE, 1024 pulses per revolution) is coupled to SPIM shaft in order to measure the rotational speed and compare it to its estimative. A magnetic powder brake Magtrol emulates the mechanical load. The SPIM windings are fed by two quadrature AC voltages with con- stant V/f ratio generated by an IGBT-based three-leg voltage source inverter (VSI) whose electrical characteristics are summarized in Table 2. The use of a three-leg inverter pre- sents many advantages over a two-leg topology such as gener- ate a zero voltage vector, avoid the circulation of an AC cur- rent in the DC link capacitor, and improve the output voltage quality in terms of harmonic distortion [6, 7, 12, 13]. The in- tegrated sensors to VSI are used to measure the currents of

Induction motors are the most widely used motors for appliances, industrial control, and automation; hence, they are often called the workhorse of the motion indus- try. They are robust, reliable, and durable. When power is supplied to an induction motor at the recommended specifications, it runs at its rated speed. However, many applications need variable speed operations. For example, a washing machine may use different speeds for each wash cycle. Historically, mechanical gear sys- tems were used to obtain variable speed. Recently, electronic power and control systems have matured to allow these components to be used for motor control in place of mechanical gears. These electronics not only control the motor’s speed, but can improve the motor’s dynamic and steady state characteristics. In addition, electronics can reduce the system’s average power consumption and noise generation of the motor. Induction motor control is complex due to its nonlinear characteristics. While there are different methods for control, Variable Voltage Variable Frequency (VVVF) or V/f is the most common method of speed control in open loop. This method is most suitable for applica- tions without position control requirements or the need for high accuracy of speed control. Examples of these applications include heating, air conditioning, fans and blowers. V/f control can be implemented by using low cost PICmicro  microcontrollers, rather than using costly digital signal processors (DSPs).

The above results are coded in the PSOC microcontroller and even programming is done to send the signal from Encoder. HT12E encoder is used. Similarly to receive the signal an decoder is used, here HT12D is used. The advantage of this Encoder and Decoder is it will convert digital data into frequency. Radio Frequency Transmission is used which has 433.3MHz and around 2km of distance.

1. INTRODUCTION In the period prior to 2003 Polytechnics in Zimbabwe had a mix of Information Communication Technologies (ICTs), varying from one institution to the other. There was no uniformity as to what ICTs individual institutions invested in, so while some institutions had several computer laboratories of clone desktops, some did not have even a single lab. While some had connected to the internet through the dialup system which came through telephone lines, some had no idea what internet was.A breakthrough came in 2003 when a non- governmental organization called VVOB, a Belgian abbreviation which translates in English to Flemish for Technical Assistance, came in with a project called the College Information Technology Enhancement Programme (CITEP), which helped to finance, train personnel and equip polytechnics with standard computer and network infrastructure (VVOB project document, 2003). They conducted training workshops for personnel, procured standard desktops, and installed fibre internet connectivity and setup Ethernet networks in these institutions. This project became the basis for mobile computing in Polytechnics. When the project ended in 2008, the institutions were now coordinated and some managed to go a step further by installing wireless access points within institutions using the fibre backbone. This allowed staff and students who had WIFI enabled devices to be able to access internet and research

The essence of social economy is the inclusive function of the labor market through which the different forms of social economy that exist in the member states can play a role in the overcoming the crisis, especially in the creating of jobs, including in social services field Opinion of the European Economic and Social Committee on the post‐ 2010 Lisbon Strategy 9, p. .