Directtorquecontrol (DTC) is a vector control strategy and it became very popular from previous two decades. The popularity is due to very fast dynamic torque response, simple structure, no coordination transformation required and absence of current and PWM controllers. In DTC, reference flux and speed are acts as inputs. Based on the errors between reference and estimated quantities and position of stator flux vector in two dimensional complex plane, voltage vectors are determined by the assisting of switching table. Variable speedcontrol drives plays an crucial role in industrialization, so this paper concentrates on speedcontrol technique of an inductionmotorusing DTC strategy and also to improve the performance characteristics, speed controller gains are tuned by means of Genetic Algorithm (GA). GA gives best fit value and corresponding controller gains are selected to tune the controller which gives better performance characteristics. And also this paper describes, variation of controller parameters and steady state speed with respect to iterations. Inductionmotor is modeled in stationary reference frame and performance characteristics are observed by the help of SIMULINK/MATLAB.
Speedcontrol of inductionmotor is necessary in industrial applications. There are several methods for the speedcontrol of induction motor.Cyclo-converters are used in very large variable frequency drives with ratings from few megawatts up to many tens of megawatts. A cycloconverter is controlled through the timing of its firing pulses, so that it produces an alternating output voltage. It can also be considered as a static frequency changer and typically contains silicon- controlled rectifiers.The development of the
Abstract:-This paper present the speedcontrol of single phase Inductionmotorusing Arduino with the controlling objectives PWM and SPWM . Induction motors are widely used Electrical Motors due to their reliability, low cost and robustness. However, Induction Motors do not inherently have the capability of variable speed of operation. Due to this reason, earlier dc Motors were applied in most of the Electrical Drives. But the recent developments in speedcontrol methods of the InductionMotor have led to their large scale use in all Electrical Drives. Out of the several methods of speedcontrol of an induction such as pole changing, frequency variation, variable rotor resistance, variable stator voltage, constant V/f control, slip recovery method etc., the closed loop constant V/f speedcontrol method is most widely used. The design, analysis, and implementation of Single phase Inverter driving InductionMotor is completely carried out using Arduino.
The project designed to control the speed of inductionmotor such as fan using android based smart phone. In home automatic related application, the convenience of remotely controlling the speed of fan can be achieved. Android mobile act as a transmitter and the transmitted signal is received by Bluetooth receiver interfaced to microcontroller 8051. Each time data is sent by android application as per code written and is executed by microcontroller to deliver supply signal to TRIAC through optical isolation. Hence the power to load connected in series with TRIAC is controlled based on received signal and speedcontrol of inductionmotor is achieved. In this design, feedback is also provided to the host. Speed counter is connected at the load i.e. at inductionmotor so that the speed can be displayed to the user. The prototype is developed and results are observed. Keywords: InductionMotor, Microcontroller, Bluetooth, KEIL software etc.
This paper presents design and implementation of vector control of inductionmotor. This method leads to be able to adjust the speed of the motor by control the frequency and amplitude of the stator voltage of inductionmotor, the ratio of stator voltage to frequency should be kept constant, which is called as V/F or vector control of inductionmotor drive. This paper presents a comparative study of open loop and close loop V/F controlinductionmotor. The V/F control is based on advent of stator voltage derivatives. Simulation is carried out in MATLAB/SIMULINK environment and results are compared for speedcontrol of inductionmotor.
In this work Microchip‟s dsPIC30F2010 digital signal controller is used. Microchip‟s dsPIC30F2010 digital signal controllers place unprecedented performance in the hands of 16-bit MCU designers. The dsPIC DSC has the “heart” of a 16- bit MCU with robust peripherals and fast interrupt handling capability and the “brain” of a DSP that manages high computation activities, creating the optimum single-chip solution for embedded control of three-phase inductionmotor . It also consists of six opto coupler for isolating the control and power circuits. In this work an optocoupler TLP250 is used to isolate the gate drive circuit and the IGBT-based power circuit. Six IGBTs of the power circuit are controlled by square wave switching technique. These square wave signals are required to derive a varying AC voltage from the power circuit. A dead time of 2 micro second is given between switching off the upper switch and switching on the lower switch and vice versa, to avoid shorting the DC bus.
control of asynchronous motor parameters like speed, torque and flux are of utmost importance. The machine learning algorithms applied in other applications [17-20] can also be used for speedcontrol with certain modifications. From the study of the control approaches, it is identified that torquecontrol of AC motor could be accomplished according to various methods ranging from low-cost Volts/Hz ratio approach to sophisticated sensor less based vector control method. But every scheme has its disadvantages like losses, the requirement of separate current control loop, coordinate transformation, current ripple and torque etc. In this work, the principles of DTC method combined with artificial intelligent controller based on fuzzy logic will be discussed and used. The controller with DTC control will be simulated on an induction machine of squirrel type under different conditions. 3.1 Principle of Vector Control
The inductionmotor finds its place amongst more than 85% of industrial motors as well as in its single-phase form in various domestic usages. Markedly a constant-speedmotor with shunt characteristic, speed drops only by a few percent from no-load to full load. Hence in the past, induction motors have been used primarily in constant speed applications. Traditional methodologies employing speedcontrol have either been high-priced or very inefficient, unlike the dc motor in which the presence of commutator and brushes require recurrent maintenance make dc motor drives improper for use in hazardous and polluted environments.
Directtorquecontrol combines the benefit of direct flux and torquecontrol into sensor less variable frequency drive that does not require a PWM modulator. Recent advances in digital signal processor and application specific integrated circuit and the theoretical concepts developed so far for direct self control makes this possible. The objective of the present work was to make a model of directtorquecontrol of three phase inductionmotor .Various speedcontrol schemes were studied and extensive literature survey was carried out for understanding the directtorquecontrol technique. MATLAB/SIMULINK was chosen as modeling and simulation tool because of its versatility. Model for directtorque controlled inductionmotor was developed using MATLAB/SIMULINK and performance of the system for different operating condition like starting, load changes, speed reversal, effect of changing the values of Kp and Ki on the performance characteristics, was studied. The model was validated by comparing the plots of various performance parameters with those available
The stator flux and torque track their reference values within the limits of two hysteresis bands with two hysteresis comparators and a switching table to obtain quick dynamic response. Torque and current ripples with variable switching operation are the major concerns with a basic DTC drive. A variable switching frequency operation is attributed to the presence of hysteresis comparators for implementing the control algorithm. The implementation of the control strategy by digital controllers requires the time discretisation of the process into smaller sampling intervals, which also leads to undesirable ripples in torque and current. A DTC drive can be operated in either torquecontrol mode or speedcontrol mode. In this paper DTC strategy with dither signal injection is implemented in order to minimize the torque ripple. The triangular dither signal of high frequency having magnitude equal to torque and flux hysteresis band is injected into the torque and flux errors respectively. This dithering technique minimizes the torque ripple to 30% compared to conventional DTC method. Several researches have been proposed to minimize the torque ripple by using modified DTC techniques in three-phase inductionmotor. The effectiveness of the proposed method is verified through MATLAB/SIMULINK simulation.
To solve the cross-coupling between induction machine dq transient stator currents Holtz et al. (2004) de- signed a stator-current controller using complex nota- tion. From this, the current controller structure em- ploying single-complex zeros is synthesized. Experimen- tal results demonstrate that high dynamic performance and zero cross-coupling are achieved even at very low switching frequency although the speedcontrol had not be presented.
For speedcontrol reason electric drives are used. The types of electric drives are AC and DC drives. Because of high efficiency, better performance, robustness and less maintenance AC drives especially InductionMotor Drives (IMD) are most commonly used in industrial applications instead of DC drives. The IMD control method is further classified as scalar and vector control method. Operating in steady state, the angular speed of current, voltage and flux linkage in the space vectors are controlled by scalar control. Hence during transient state the scalar control doesn’t operate in space vector position. The instantaneous position of current, flux linkage and voltage of space vector along with the angular speed and magnitude are controlled with the vector control.- The vector control allows controlling of inductionmotor like a separately excited dc motor.
Directtorquecontrol (DTC) is one of the control strategies of the Torquecontrol of Induction machine. Sliding Mode Control (SMC) is known for its capability to cope with bounded disturbance as well as model imprecision which makes it ideal for the robust nonlinear control of IM drives. In this Paper Directtorquecontrol (DTC) of the inductionmotor controlled by two fuzzy logic based sliding modecontrollers.The aim is to control effectively the torque and flux. Torquecontrol of an induction machine based on DTC strategy has been developed using Ziegler-Nichols (ZN), fuzzy sliding mode1(FSM1) and fuzzy sliding mode2 (FSM2) speed controllers and a comprehensive study is presented in this paper. The model is constructed and simulated by using Matlab/Simulink for different operating conditions such as reference speed. Several numerical simulations have been carried out in a steady state and transient operation on a speedcontrol mode. The results shows that the FSM2 gives better performance with less ITAE
ABSTRACT: This paper, presents speedcontrol and torquecontrol method for Inductionmotor, by using DTC based fuzzy logic, it is applied in switching select voltage vector .The comparison with conventional directtorquecontrol (DTC), show that the use of the DTC_FL , reduced the torque, stator flux, and current ripples. The validity of the proposed methods is confirmed by the simulative results
________________________________________________________________________________________________________ Abstract - Three phase induction motors are most widely used electric motor. In addition to that eighty percentage of mechanical power used by industries are provided by three phase induction motors and also in many industrial applications the inductionmotor are used because of the merits like easy maintenance, low cost, robustness and better performance. In this paper the directtorquecontrol model is designed and tested through MATLAB / SIMULINK software for torque and speedcontrol of inductionmotor. In addition to these parameters like d and q stator current, d and q axis flux, torque and speed are obtained graphically.
Industrial loads require operation at wide range of speed. Such loads are generally termed as variable speed drives. These drives demand precise adjustment of speed in a stepless manner over the complete speed range required. The loads may be constant torque or function of speed. These loads are driven by hydraulic, pneumatic or electric motors. An industrial drive has some special features when driven by electric motors. Inductionmotor have provide the most common form of electromechanical drive for industrial, commercial and domestic application that can operate at essentially constant speed. Induction machines have simpler and more rugged structure, higher maintainability and economy than dc motor. They are also robust and immune to heavy loading. The possible forms of drive motors are dc drives, ac drives. Dc motor are versatile for the purpose of speedcontrol but they suffer from disadvantage impose by the commutator. On the other hand ac drives are variable competitor with the advent of the power electronic controller technology.
There are two different loops corresponding to the magnitudes of stator flux and torque. The reference values of stator flux modulus and torque are compared to their actual values. The resulting errors are fed to the input of look up table. The DTC require stator flux and torque estimations which can be performed as proposed, by mean of two different phase currents and state of inverter. The basic principle of DTC is to directly manipulate the stator flux vector such that the desired torque is produced. This is achieved by choosing an inverter switch combination that drives the stator flux vector by directly applying the appropriate voltages to the motor windings The directtorque method performs very well even without speed sensors. However, the flux estimation is usually based on the integration of the motor phase voltages. Due to the inevitable errors in the voltage measurement and stator resistance estimate the integrals tend to become incorrect at low speed. If continuous operation at low speeds including zero frequency operation is required, a speed or position sensor can be added to the DTC system. With the sensor, high accuracy of the torque and speedcontrol can be maintained in the whole speed range.
Abstract: In this paper, the author proposes a sensorless directtorquecontrol (DTC) of an inductionmotor (IM) fed by seven-level NPC inverter using artificial neural networks (ANN) and fuzzy logic controller. Fuzzy PI controller is used for controlling the rotor speed and ANN applied in switching select stator voltage. The control method proposed in this paper can reduce the torque, stator flux and total harmonic distortion (THD) value of stator current, and especially improve system good dynamic performance and robustness in high and low speeds.
In this paper the directtorquecontrol of IMD using P and PI controller has been presented. It has been observed by comparing the torque, speed and stator flux characteristics of PI and P controller that the stator flux is reduced in PI controller and torque ripples are also reduced by using PI controller as compared with P controller. But due to the property of overshooting of PI controller small disturbance is observed in the starting of speed and torque and afterwards the required speed and torque is obtained. So it can be concluded from the results that stator flux and torque ripples are reduced more by using PI controller as compared with the P controller. The two independent torque and flux hysteresis band controllers are used for controlling the torque and flux.
control technique was the Constant Volts per Hertz (CVH) strategy, so called because it adjusts the stator voltage magnitude proportionally to the operating frequency to keep the IM stator flux approximately constant. This is a simple control technique, but it has a limited and non-accurate speed range, particularly at low speeds, and has a poor torque response. The introduction of the vector control technique partially solves the IM control problem. In the 70’s, F. Blaschke developed the IM Field Oriented Control (FOC). In this scheme, torque and flux of an inductionmotor are controlled independently by decoupling the stator current into its orthogonal components. The FOC method has achieved a quick torque response. In FOC, exact identification of parameters is required.