Speed control in DC and AC drives

2013

The separately excited Direct current (DC) motors with conventional Proportional controller is generally used in industry. This can be easily implemented and are found to be highly effective if the load changes are small. However, in certain applications, like rolling mill drives or machine tools, where the system parameters vary substantially and conventional PI or PID controller is not preferable due to the fact that, the drive operates under a wide range of changing load characteristics. Here in this paper a speed response is analyzed using PI control for a separately exited dc drive. The responses of steady state error, speed overshoot etc. are analyzed for a separately excited dc drive with small changes in load torque using the said controller. Performances of these controllers are verified by simulation in MATL

International Journal of Engineering and Advanced Technology

In developed nations, industries are made to function at control engineering costs via the use of appropriate control schemes for dc motors. This paper introduces the role played by dc motors in industries thereby necessitating the analysis and performance validation of dc motor in Internal Model Control (IMC) scheme as against the Proportional– Integral–Derivative (PID) control schemes that is widely used in most industries. Theories on dc motor model, PID and IMC controller were detailed to paved the way for the methodical approach of getting specifications and transfer function for a typical dc motor (model RMCS-3011). Matlab/Simulink software was then used to tune the PID controller for the purpose of finding the values of PID gains that meets the design requirements to achieve best performance, thereby enabling the simulation of the PID controller. Using Matlab m-file environment, IMC controller transfer function was generated and simulated. The IMC controller transfer function...

2019

The use of DC motor drive system has been in tradition for quite a long time. The reason being its good regulation of speed, starting is frequent, can be reversed and braked easily. As it is used in many industrial applications many of them require its speed to be controlled. Hence, the two method for controlling its speed is Armature voltage control and field control. The use of Armature voltage method has been demonstrated here in DC separately excited Motor drive. To further modifies its speed regulation process a controller is used. Two controllers are implemented Proportional Integral (PI) and Proportional Integral Derivative (PID). The parameters of these controllers are processed and enhanced via the use of Differential Evolution Algorithm (DE). The main objective of the present work is to have minimum rise and settling time while minimizing the maximum overshoot. To verify the performance of the given DE based PI and PID controller used in DC drive system, the result of thes...

International Journal of Engineering Sciences & Research Technology, 2013

The separately excited Direct current (DC) motors with conventional Proportional controller is generally used in industry. This can be easily implemented and are found to be highly effective if the load changes are small. However, in certain applications, like rolling mill drives or machine tools, where the system parameters vary substantially and conventional PI or PID controller is not preferable due to the fact that, the drive operates under a wide range of changing load characteristics. Here in this paper a speed response is analyzed using PI control for a separately exited dc drive. The responses of steady state error, speed overshoot etc. are analyzed for a separately excited dc drive with small changes in load torque using the said controller. Performances of these controllers are verified by simulation in MATL

Electrical Engineering, 2018

The paper presents an analytical design of the current and the speed controllers for robust control of electrical drives with the good performance index. The design procedure with a practical implementation of the speed and current controllers is performed in an indirect field-oriented controlled elevator drive with an induction motor. It is demonstrated that both controllers are simultaneously tuned with a free parameter which allows the operator to control the process so the desired robustness/performance is achieved. The proposed controller design procedure is verified with the both, numerical simulations and experimentally. Keywords Current controller • Speed controller • PI controller • Performance index • Vector control 1 Introduction Controlled electrical drives (CED) have a broad application in the process industry, which has greatly aroused motivation to improve them. Electrical drives with an induction motor are the mostly used electrical drives [1]. In controlled drives, it is necessary to develop appropriate control algorithms so the desired robustness and performance of such systems are achieved. The speed and the current controllers are mostly used in CED in comparison with other types of controllers. The cascade structure with internal current and external speed controller is commonly used. Direct current (DC) motors were mostly used in controlled electrical drives up until the 1990s. These motors are much less B Bojan Z. Knežević

University of Khartoum Engineering Journal, 2017

This paper describes a separately excited DC motor speed control using armature voltage control method, based on traditional Proportional- Integral- Derivative (PID) controller, and pole assignment, feedback control technique. The main objective of the proposed controller is to control the speed of a DC motor shaft rotation and overcome problems like overshoot, and increasing the system model order, that are caused by PID controller, with a step response. Results obtained with Ziegler – Nichols PID controller were compared with those obtained using pole placement. DC motor response contains a 24% overshoot with PID controller; compared with 0.0286% overshoot. In the response of pole placement controller, it is found that pole placement reduces system overshoot to 0.0015% of the closed loop system.

During the last decades, the rapid development of power semiconductor devices has allowed the increased use of adjustable speed ac drives in a variety of applications, especially in the process-control industry. In many applications, the capability of controlling the speed effectively can improve the efficiency of the ac motors and thus lead to large savings in energy. Among the several approaches used to control ac motors is the direct torque control (DTC), occupies an important place. DTC of ac motors is known to have very favorable control performance and implementation properties. The control scheme is based on the control of torque and flux utilizing the stator flux field orientation. Field orientation is achieved using advanced motor theory to calculate the torque directly and without using modulation. DTC enables the control of speed and torque over a very broad range. The torque response is particularly fast and it is possible to maintain constant speed, even when the mechanical load imposes sudden and unexpected mechanical shock. Thus the advancement of this ac drive technology enables the machine to achieve excellent dynamic performance. This paper is an attempt to investigate and evaluate the characteristics and operating principle of DTC scheme. Experimental tests have been carried out using ABB speed drive unit (ACS800 model), squirrel-cage induction motor and three-phase pendulum machine with integrated torque pickup to validate the effectiveness and feasibilities of this controlling technique.

IET Power Electronics, 2013

In vector-controlled AC drives, the design of current controller is usually based on a machine model defined in synchronous frame coordinate, where the drive performance may be degraded by both the variation of the machine parameters and the cross-coupling between the d-and q-axes components of the stator current. In order to improve the current control performance an alternative current control strategy was proposed previously aiming to avoid the undesired crosscoupling and non-linearities between the state variables. These effects are assumed as disturbances arisen in the closed-loop path, extracted by a disturbance observer and then injected into the current controller. In this study, a revised version of a disturbance observer-based controller and a well known complex variable model-based design with a single set of complex pole are compared in terms of design aspects and performance evaluation by simulation and by experiment for two different sampling rates. Several comparative results that verify the promising performance of the proposed control scheme are presented. The advantages of the proposed controller are an easy implementation and offering a unique solution for the variation of the parameter and the cross-coupling effect. Moreover, it provides a better performance, smooth and low noisy operation with respect to the complex variable controller.

IEEE Transactions on Industry Applications, 1998

In this paper, the internal model control (IMC) method is applied to ac machine current control. Permanent magnet synchronous machines and induction machines are considered. The result is synchronous-frame proportional integral (PI) or PI-type controllers, the parameters (gain and integration time) of which are expressed directly in certain machine parameters and the desired closed-loop bandwidth. This simplifies the controller design procedure, eliminating or reducing the need for trial-and-error steps, and is the main purpose for using IMC.

The speed of a DC motor can be varied by controlling the field flux, the armature resistance or the terminal voltage applied to the armature circuit. The three most common speed control methods are field resistance control, armature voltage control, and armature resistance control . In this section, modeling procedure of these three methods and feedback control method [2] for DC motor drives for dynamic analysis are presented.