ASIC design for DTC based speed control of induction motor

Induction motor is very popular in industrial applications due to simple construction, low cost, and cheap maintenance costs. Speed control of induction motor requires frequency and magnitude voltage control. Some Volt/Hz control strategies are applied in speed control of induction motor with various methods such as direct torque control, vector control, harmonic elimination. These methods are very popular but require complex calculations. This paper discusses a simple method to operate an induction motor using the SPWM Volt/Hz, by using a lookup table method. This method contains important numbers as a reference for sinusoidal reference signal used to produce SPWM signal by comparing reference signals and triangular wave carrier signals from dsPIC microprocessor. SPWM Volt/Hz is used because the manufacturing process does not require complex calculations, easy to operate and reliable for induction motor speed operations. To prove that SPWM Volt/Hz can apply on speed control of induction motor, analysis simulation and experimental works were done. They show the proposed control strategy is capable to operate induction motor at the proper speed.

In the induction motor speed control without sensors operated by the method Field Oriented Control (FOC) was required an observer to estimate the speed. Obsever methods have been developed, among others, was the method of Self-Constructing Fuzzy Neural Network (SCFNN) with some training algorithms such as backpropagasi (BP). Levenberg Marquard (LM) etc.. In the induction motor control techniques were also developed methods of Direct Torque Control (DTC) with observer Recurrent Neural Network (RNN). This paper compares the performance of the motor response to initial rotation between SCFNN observer method that uses the LM training algorithm with DTC control technique with RNN observer. From the observation performance of the motor response to initial rotation of the two methods shows that the LM method has better performances than the RNN. This can be seen on both the parameters : overshoot, rise time, settling time, peak and peak time. With the right method, can enhance better performance of the system. With the improvement of system performance, is expected to increase work efficiency in the industrial world, so overall, particularly for systems that require high precision, FNN methodcan be said to be better. Keywords: Motor Speed control without sensors, FOC, SCFNNO, DTC, Levenberg Marquardt and RNN. DOI: http://dx.doi.org/10.11591/ijpeds.v1i1.66

This paper presents the scalar control as well as direct torque control for speed control of induction motor. The scalar control is an easy to implement but it gives poor dynamic response. In addition to the scalar control the space vector pulse width modulation (SVPWM) is used for effective utilization of the dc-link voltage i.e. SVPWM is having the good voltage regulation and reduces the considerable harmonics in voltage as well as current of the inverter. The dynamic response of the induction motor is improved using direct torque control with SVPWM technique. The performance of induction motor with scalar control and direct torque control is simulated in the Matlab environment and compared their response under similar operating conditions. The dynamic performance, the speed regulation, THD in the current, and the torque distortion of induction motor are effectively improved with direct torque control (i.e. lesser transient time) even while applying the load in comparison to scalar control.

Induction motors are currently used in many industrial applications. Thus, their control techniques have received a lot of interest. An efficient method of induction motor control is the Direct Torque Control (DTC). It is considered particularly interesting since it is independent of machine rotor parameters and requires no speed or position sensors. This paper presents a simulation of a DTC strategy for three-phase induction motors based on the Field Programmable Gate Array (FPGA) technology. The real controller is not experimentally tested. A specific methodology for the hardware description language in VHSIC Hardware Description Language (VHDL) is presented. This paper summarizes the prior work before implementing the experimental FPGA control of an induction motor. This methodology allows one to verify the behavior of the VHDL codes before their implementation, reducing the risks of significant changes when implemented. The VHDL design technique for DTC-based speed control is designed through the descriptions of coordinate transformation, speed controller, stator flux and torque estimator, stator flux and torque controller, and stator flux position detector. The simulation is performed using the MATLAB/Simulink, DSP Builder, and Quartus II software, on an Altera DE2-115 board. Simulation results verify the validity of the proposed method.   Key words: Digital control, induction motor, digital signal processing, VHSIC Hardware Description Language (VHDL).

Because of its low maintenance and robustness, induction motors have many applications in the industries. Most of these applications need fast and smart speed control system. This paper introduces a smart speed control system for induction motor using fuzzy logic controller. Induction motor is modeled in synchronous reference frame in terms of dq form. The speed control of induction motor is the main issue achieves maximum torque and efficiency. Two speed control techniques, Scalar Control and Indirect Field Oriented Control are used to compare the performance of the control system with fuzzy logic controller. Indirect field oriented control technique with fuzzy logic controller provides better speed control of induction motor especially with high dynamic disturbances. The model is carried out by using Matlab/Simulink computer package. The simulation results show the superiority of the fuzzy logic controller in controlling three-phase induction motor with indirect field oriented control technique.

Direct Torque Control (DTC) and Predictive Torque Control (PTC) Strategies emerged as popular techniques for speed control of Induction Motor Drives. In this article, an effective PTC strategy is introduced to an Open-End Winding Induction Motor Drive (OEWIMD) to control torque and flux directly. PTC offers all the features of classical DTC and it provides lesser ripple in torque and flux. The limitations of classical PTC are: (i) higher common-mode voltage (ii) variable switching frequency (iii) high computational burden and (iii) selection of weighting factors. To trounce some of these problems PTC of OEWIMD is developed. OEWIMD is operated with dual inverter configuration. In dual inverter configuration, if the inverters are operated with equal DC bus voltages (1:1 ratio), it can deliver ‘18’ space vector locations, out of these space vector locations only six active space vectors and a null vector has been considered. The voltage vectors used to implement the proposed algorithm can maintain less common-mode voltage. The proposed algorithm is verified by comparing the obtained experimental results with simulation results.

The direct torque control (DTC) suffers from high torque and flux ripples due to the use of hysteresis comparators. In this paper, an alternative method is presented for induction motor drive known by the model Predictive Torque Control (PTC). This technique includes the inverter model in control design and does not use any modulation block. The optimal selection of inverter switching states minimizes the error between references and the predicted values of control variables by the optimization of a cost function. Consequently, it reduces ripples and solve DTC drawbacks. Furthermore, this paper proposes an improvement in the external speed loop for PTC scheme. A fuzzy logic controller replaces the traditional PI controller to ensure more accurate speed tracking and increase the robustness against disturbance and uncertainties. The effectiveness of the presented algorithms is investigated by an experimental implementation with the aid of real-time interface (RTI) based on dSpace 1104.

Induction motor drives are grabbing attention from many researchers due to its features and applications. Among many available control methods of the induction motor drives, Direct Torque Control (DTC) is a powerful technique and it is having a wide range of applications in industries. In the conventional DTC method, only one controller is utilized to obtain reference torque where reference flux becomes constant. Hence, speed control of induction motor under DTC having its limitation on flux region. Consequently, a second controller is included in this paper to manage the flux by generating a reference flux derived from the discrepancy between the motor speed and its reference. However, conventional PI or PID controllers are unable to deliver its output effectively under rapid variations in the system. Hence, Fractional Order Proportional-Integral-Derivative (FOPID) controllers are incorporated in the proposed DTC method where utilized two FOPID controllers to regulate both torque and flux simultaneously. Further, Space Vector Pulse Width Modulation (SVPWM) is also included in the proposed control method to produce accurate and instant pulses for achieving accurate responses. In this study, the inverter is utilized with two FOPID controllers alongside the SVPWM technique. The proposed control method can effectively minimize ripples in both flux and torque. OPAL-RT modules based Hardware - in the - Loop (HIL) system is developed for presenting various outcomes to enhance the presented control.

This paper presents a hybrid wavelet-fuzzy based multiresolution (MR) controller for robust speed control of induction motor. The discrete wavelet transform (DWT) is used to decompose the error between the actual speed and command speed of the induction motor drive in to different frequency components. A self-tuning fuzzy logic is used for online tuning of the controller parameters. The proposed controller has the ability of meeting the speed tracking requirements in the closed loop system. The complete indirect field oriented control scheme incorporating the proposed wavelet-fuzzy based MR controller is investigated theoretically and simulated under various dynamic operating conditions. Simulation results are compared with that of conventional PI controller and fuzzy based PI controller. The speed control scheme incorporating the proposed controller is implemented in real time using the digital processor (DSP) control board. Simulation and experimental results validates the effectiveness of the proposed controller over conventional controllers and proves to be more suitable for high performance applications.

This paper proposes a design process of speed controller for induction motor using tabu search algorithm. The proposed process has two parts. The first part is optimization of the initial parameters of input-output. And the second part is changing parameters of input-output using tabu search. Proposed tabu search is improved by neighbor solution creation using Gaussian random distribution. In order to see the usefulness of the proposed method, it is applied to the sensorless speed controller of an AC induction motor system. The performance of this approach is verified through simulation.

This paper proposes the speed control of induction motor (IM) fed by wind turbine using imperialist competitive algorithm (ICA). The wind turbine plays as a prime mover to a connected direct current (DC) generator. Pulse width modulation (PWM) is used to get three-phase alternating current (AC) voltage from the output of DC generator. The proposed design problem of speed controller is established as an optimization problem. ICA is adopted to search for optimal controller parameters by minimizing the time domain objective function. The behavior of the proposed ICA has been estimated with the behavior of the conventional Ziegler–Nichols (ZN) and genetic algorithm (GA) to prove the superiority of the proposed ICA in tuning proportional plus integral (PI) controller. Also, the behavior of the proposed controller has been tested over a wide range of operating conditions. Simulation results confirm the better behavior of the optimized PI controller based on ICA compared with other algorithms.

Speed control technique are generally essential in adjustable speed drive system. This system requires variable voltage and frequency supply which is obtained from a three phase voltage source inverter. This paper presents the speed control of induction motor fed by a three phase voltage source inverter using pulse width modulation method and universal bridge. To control the peak dc link voltage of voltage source inverter, a PID controller was designed. The performance analysis of open loop and closed loop speed control system is carried out in Matlab/Simulink. The simulation result shows that the speed controller has a good dynamic response and can control the induction motor successfully with a better performance.

Because traditional direct torque control (DTC) has unfixed switching frequency and ripple of torque and flux, deadbeat direct torque and flux control (DB-DTFC) of interior permanent magnet synchronous motor (IPMSM) is studied. At first, DB-DTFC based on IPMSM mathematical model is deduced. The calculated proper voltage vector can make reference torque and stator flux during one sampling period. But, parameters of IPMSM such as inductance of stator windings vary with its operation and affect on torque and flux performance. Secondly, parameter identification based on recursive least squares with forgetting factor is analyzed, which can identify IPMSM parameters online and eliminate their affects on performance of torque and stator flux. Finally, simulations are carried out and validate the proposed DB-DTFC which has both excellent dynamic and steady performance.

Purpose. The main objective of this work is to demonstrate the advantages brought by the use of space vector modulation technique in the direct torque control of the induction motor. To achieve this purpose, two different direct torque control approaches (with space vector modulation) are proposed and studied from a comparative aspect with each other and with the conventional direct torque control. The novelty of this work consists in the employment of an Integral-Proportional (IP) speed controller in the two proposed direct torque control approaches and a more in-depth evaluation for their performance mainly the switching frequency of inverter semiconductor components and motor torque ripples. Methods. Two different direct torque control approaches that use the space vector modulation strategy and/or fuzzy-logic control, are described in detail and simulated with IP speed controller. The simulation experiments are carried out using Matlab/Simulink software and/or fuzzy-logic tools. Results. Practical value. Comparison results show that the two proposed direct torque control structures (with space vector modulation) exhibit a large reduction in torque ripples and can also avoid random variation problem of switching frequency (over a wide range of speed or torque control). On the other hand, the use of IP speed regulator ensured good dynamic performance for the drive system as well as considerably minimized peak overshoot in the speed response. Practically all of these benefits are achieved while retaining the simplicity and the best dynamic characteristics of the classical direct torque control, especially with the modified direct torque control approach in which the design or implementation requires minimal computational effort.

This paper represents comparative performance analysis between switching table based direct torque control (ST-DTC) and direct torque control with space vector modulation (DTC-SVM) for different torque and speed pattern for three-phase induction motor. One of the modern control methods used to regulate AC motor speed is DTC. Basically, DTC is control scheme which directly control the stator flux and torque. Conventional DTC uses switching table for selection of voltage vector. In conventional DTC there is some disadvantages like high torque ripple, machine vibration and noise which are overcome in DTC-SVM technique. In DTC-SVM technique space vector modulation used to improve efficiency of motor by selecting the appropriate voltage vector. Two-level inverter is used for both DTC and DTC-SVM technique. Moreover, in DTCSVM technique have many more advantages like low ripple torque in transient state, lower current distortion, lower switching losses etc. Both the proposed techniques are implemented using MATLAB/ SIMULINK software. DTC-SVM technique provide better results as compare to ST-DTC technique.