Optimal Design and Control of Multi-Motor Drive System for Industrial Application

In this paper, the topology of the adjustable speed drive with active front end rectifier is considered in terms of application in multi-motor drives. A dynamic model of the rectifier with a coupled LCL filter is presented. A simulation model has been developed for the analysis of multi-motor drive system dynamics and power flow. Based on the simulation model, the functional possibilities of reversible induction motor drive with active front end converter and multiple voltage source inverters on a common DC bus at the motor side are analysed. One example of the application of a complex full regenerative multi-motor drive system on a common DC bus for an industrial crane, implemented with Siemens converters, is shown. The motor and generator mode of operation from the aspect of energy saving as well as the influence of drives on the distribution network from the aspect of higher harmonics and power factors are analysed. Siemens\u27s original software, Starter commissioning tool, for drives configuration and data acquisition is used

DISCRETE TIME QUASI-SLIDING MODE-BASED CONTROL OF LCL GRID INVERTERS

Application of a discrete time (DT) sliding mode controller (SMC) in the control structure of the primary controller of a three-phase LCL grid inverter is presented. The design of the inverter side current control loop is performed using a DT linear model of the grid inverter with LCL filter at output terminals. The DT quasi-sliding mode control was used due to its robustness to external and parametric disturbances. Additionally, in order to improve disturbance compensation, a disturbance compensator is also implemented. Also, a specific anti-windup mechanism has been implemented in the structure of the controller to prevent large overshoots in the inverter response in case of random disturbances of grid voltages, or sudden changes in the commanded power. The control of the grid inverter is realized in the reference system synchronized with the voltage of the power grid. The development of the digitally realized control subsystem is presented in detail, starting from theoretical considerations, through computer simulations to experimental tests. The experimental results confirm good static and dynamic performance

VOLTAGE SAG SENSITIVITY OF INDUSTRIAL VECTOR CONTROLLED INDUCTION MOTOR DRIVES – A COMPARATIVE STUDY

Sensitivity of adjustable speed drives (ASDs) on voltage sag events represents one of the most challenging problems in modern industrial facilities. In this paper, a comprehensive experimental verification of vector-controlled ASDs is conducted under the most-frequent sag types. The obtained results are faced with static and dynamic requirements in speed and torque controlled applications. Besides influence of DC-link parameters, selection of the applied control method and the controller settings can have crucial impact on performance deterioration. Examined industrial ASDs exhibited voltage sag susceptibility with fault error codes under the deeper voltage sags, while under the voltage sags with residual voltage above under-voltage limit they showed speed degradation

THE MONOSPIRAL MOTORISED CABLE REEL IN CRANE APPLICATIONS

The main consideration of any reeling system is the effect it has on cable tensions and hence cable life. This paper explains the relationship of reel torque to cable tensions and the reasons why this relationship is so important. Such system is characterized by variable parameters, primarily a variable moment of inertia and a variable diameter of the coiled cable. For these reasons, in order to ensure proper dimensioning of the drive, it is necessary to know the motor torques that need to be developed as a function of the coiled cable. The motor should be able to develop the required torques in a very wide speed range. It is shown that for properly sizing the motor it is necessary take into account the dynamics of the cable reel drive. In this paper monospiral motorized cable reel for winding power cable in crane applications with frequency converter fed induction motor is analyzed. Also, the equipment selection procedure for the real crane with concrete data is shown. Experimental results are recorded during the crane commissioning in real condition

An Improved Scheme for Voltage Sag Override in Direct Torque Controlled Induction Motor Drives

This paper analyses symmetrical and unsymmetrical voltage sag effects on the torque and speed deviation in direct torque controlled (DTC) induction motors (IMs) for adjustable speed drives (ASDs). The capability of an ASD for continuous normal operation in case of short supply disturbances is essential for high performance drives. In this paper, an updated scheme is proposed for boosting ASD performances during supply disturbances with voltage reduction. Flux weakening is an effective method to overcome the torque-decreasing problem in case of DC-link voltage diminishing. It is also shown that speed reduction is an efficient procedure to obtain the voltage sag insensitivity of an ASD, which is appropriate for the existing industrial applications. Extensive laboratory testing has been conducted to verify the performances and effectiveness of the proposed control algorithm. The suggested method requires only a modification of converter control software or operating speed change without any additional hardware components. Extended tests under various voltage sags events were carried out on a 1.5 kW laboratory drive, and the obtained results have been compared with an industrial DTC drive

A Building Block Method for Modeling and Small-Signal Stability Analysis of the Autonomous Microgrid Operation

The task of the whole microgrid state-space matrix creation is usually done in a preferred textual programming language, and it presents a complicated, time-consuming, and error-prone job for a researcher without good coding practices. To ease the modeling task, contribute to the adaptation of new microgrid structures, control algorithms, and devices, and to improve the flexibility of the model, a graphical element building block method is proposed in this paper. With the proposed approach model creation of the whole microgrid is reduced to the creation of the individual element state-space model that is linked with other elements in a logical way with a graphical connection. Elements are then grouped into meaningful wholes and encapsulated with the appropriate graphical user interface that enables easy parameter modification and model complexity change. More detailed DC/DC and DC/AC models of converters than those in the literature concerning microgrid stability are presented in this paper. Those converters are incorporated in a microgrid, whose model is created using the proposed approach in MATLAB/Simulink. The dynamic response examination of the model remains easy, just as with all Simulink models, while for the linear system analysis, a specialized toolbox is used

Discrete-time sliding mode control of linear systems with input saturation

The paper proposes a discrete-time sliding mode controller for single input linear dynamical systems, under requirements of the fast response without overshoot and strong robustness to matched disturbances. The system input saturation is imposed during the design due to inevitable limitations of most actuators. The system disturbances are compensated by employing nonlinear estimation by integrating the signum of the sliding variable. Hence, the proposed control structure may be regarded as a super-twisting-like algorithm. The designed system stability is analyzed as well as the sliding manifold convergence conditions are derived using a discrete-time model of the system in the δ-domain. The results obtained theoretically have been verified by computer simulations

Discrete–Time Sliding Mode Control of Linear Systems with Input Saturation

The paper proposes a discrete-time sliding mode controller for single input linear dynamical systems, under requirements of the fast response without overshoot and strong robustness to matched disturbances. The system input saturation is imposed during the design due to inevitable limitations of most actuators. The system disturbances are compensated by employing nonlinear estimation by integrating the signum of the sliding variable. Hence, the proposed control structure may be regarded as a super-twisting-like algorithm. The designed system stability is analyzed as well as the sliding manifold convergence conditions are derived using a discrete-time model of the system in the δ-domain. The results obtained theoretically have been verified by computer simulations

Effects of unsymmetrical voltage sags on industrial adjustable speed drives

This paper researches unsymmetrical voltage sag influence on torque ripple in scalar controlled (V/Hz), rotor field oriented (RFO) and direct torque controlled (DTC) drives. Electric drives performance degradation during voltage sag mainly depends on the used control algorithm. Industrial drives with all three types control methods are experimentally tested. Experiments with digital observer's application confirm the proposed solution.