Dynamic response analysis of induction motor drive influenced by controller design methods

This paper analyzes the input admittance/impedance characteristics of a permanent-magnet brushless AC motor drive system, taking account of the influence of both current and speed control loops as well as the motor and inverter losses. It is shown that, if voltage feedforward compensation is not employed, the input admittance of the drive system differs significantly from that of an ideal constant power load, and is influenced by the speed and current control loop bandwidths. It is also shown that, when the drive is connected to a DC supply via an LRC filter, the magnitude of the input admittance at the filter resonant frequency has a crucial effect on system stability margin.

This paper looks at design of a controller for an induction motor electrical drive useful for high speed railway applications. The design of the controller is based on the cascade control mode using the standard model of the motor referred to d-q axes fixed with the rotor flux vector. It is assumed that the speed and the rotor flux are the variables to be controlled and their dynamics must be decoupled, which is accomplished by means of a nonlinear compensator, which gives decoupling of the direct and in-quadrature currents. According to the aforementioned cascade control mode, the bandwidth of the current inner control loops must be selected higher than that of the speed and rotor flux outer control loops. To take into consideration the remarkable uncertainties in the knowledge of the inertia coefficient, adaptive control techniques are used to design the speed control loop. To cope with uncertainties in electromagnetic parameters, robust control techniques are used for designing the rotor flux, the direct, and the in-quadrature current loops. Simulation experiments are displayed to test the entire controller.

In this research, the performance of the brushless doubly fed induction generator (BDFIG) based wind turbine is studied under sudden disturbances, which occur as a result of the secondary loads change which connected in the terminals of wind turbine and wind speed change. The simulation has been executed at different loads. This paper presents also a simulation for simple control scheme of the BDFIG driven by wind turbine is controlled at unity power factor. The control scheme is designed to keep the voltage constant at (1p.u) value due to sudden change of loads and wind speed. the control system is implemented with PI controller to control the back-to-back converters utilized in the control winding circuit of the BDFIG wind turbine. Two current control loops are designed for regulating control winding current components( icd-icq). The d-axis reference current is estimated using the reactive power control loop to operate at unity power factor and keep the voltage constant at 1p.u value. The q- axis reference current is estimated using the speed control loop. The parameters of PI controllers are calculated by using Ant Colony Optimization (ACO)method. The performance of proposed PI controller is examined through MATLAB simulation of the overall wind energy conversion system using BDFIG and the system is subjected to different disturbances in terms of load and wind speed variation. The simulation results validate the effectiveness and powerful of the control system in sense of less overshoot and fast response.

Adaptive and Robust Cascade Schemes for Thyristor Driven DC-Motor Speed Control

Two-motor application has become a very attractive filed in important field which high performance is permitted to achieve of position, speed, and acceleration. In the elevation axis of telescope control system, two-motor direct drive is proposed to enhance the high performance of tracking control system. Although there are several dominant strengths such as low size of motors and high torsional structural dynamics, the synchronization control of two motors is a very difficult and important. In this paper, a multi-loop control technique base master-slave current control is used to synchronize two motors, including current control loop, speed control loop and position control loop. First, the direct drive function of two motors is modeled. Compared of single motor direct control system, the resonance frequency of two motor control systems is same; while the anti-resonance frequency of two motors control system is 1.414 times than those of sing motor system. Because of rigid coupling for direct drive, the speed of two motor of the system is same, and the synchronization of torque for motors is critical. The current master-slave control technique is effective to synchronize the torque, which the current loop of the master motors is tracked the other slave motor. The speed feedback into the input of current loop of the master motors. The experiments test the performance of the two motors drive system. The random tracking error is 0.0119" for the line trajectory of 0.01°/s.

Direct current control has been used in many voltage source power converters connected to utility grid, such as Static Var Generators (SVGs) and parallel Active Power Filters (APFs). In their stationary coordinates control systems, there are usually two closed control loops. One is the current loop and the other is the voltage loop. In practical applications, because the voltage source converters are connected to the grid, the output current will be affected and very often a command-tracking error exists in the current control loop. In this paper, a detailed analysis and design considerations are carried out to investigate this command-tracking error caused by the source voltage. Based on the obtained current loop transfer function and block diagram of the system, analytical expressions of the current control error are derived. The variables that affect the current control errors are then identified. The relationship between the circuit/control parameters and the current control errors are extensively explored. The command-tracking error affects the peak value of the modulation wave. When we design a fully digital control system, the peak value of the modulation wave is smaller than the peak value of the carrier wave. Then, according to choosing the values of the variables that affect the command-tracking error, the methods to design a fully digital direct current controlled voltage source converters connected to the grid are presented. The computer simulation investigations and hardware experimental results verify the analysis and design considerations.

Microgrid (MG) control in off-grid mode of operation is one of the main challenges in MGs. Under different loading conditions, voltage and frequency deviate from their nominal limits. The droop control method that applied with the current control and voltage control loops can restore the MG voltage and frequency to their nominal limits. However, it can’t regulate these parameters to their specified values. Additionally, the droop control method can’t do well when the system supplies either nonlinear or unbalanced loads. This paper proposes a control technique for adjusting the voltage and frequency of an MG in islanded mode under different loading conditions. The proposed method is based on applying the H-infinity ($$H\infty$$) robust control as a secondary controller with the droop control method to improve its performance. The proposed method is composed of four stages including; droop control loop, voltage control loop, current control loop and control loop for inductance–capacitance–inductance (LCL) filter and coupling circuit. $$H\infty$$ control has an internal model that can control the frequency and improve the system power quality by decreasing the disturbance frequencies. Moreover, it has two weighted parameters $$\xi$$ and $$\mu$$ that must be correctly adjusted to improve the stability of the system. For a proper adjusting of these parameters, the Harmony Search (HS) optimization method is applied. To prove the effectiveness and superiority of the proposed method, it is applied on a test system with three different loading scenarios using MATLAB/Simulink program. The results are compared with those of droop controller and they confirm that the proposed control method is more effective in controlling the microgrids under islanded mode operation.

Augmenting effectiveness of control loops of a PMSG (permanent magnet synchronous generator) based wind energy conversion system by a virtually adaptive PI (proportional integral) controller

Separately Excited DC motors (SEDCM) are widely used in industries because of their advantages in easy speed control and high performance. Their speed can be controlled by Armature voltage control and Field voltage control up to the base speed and above the base speed respectively. A rectifier or chopper is used as a converter to convert a fixed DC into variable DC to provide speed control to the motor. Many controllers have been applied for the control of motor speed. A closed loop control model has been developed having two control loops i.e. a speed control loop followed by a current control loop. Many researchers have proposed different models for this purpose. This paper presents a literature review of the research work done in this field till date. A comparative analysis is also done between the conventional methods and Artificial Neuro Fuzzy Inference System (ANFIS) based controller to find the best suitable method.

This paper presents the vector control scheme for an interior permanent magnet synchronous motor (IPMSM) drive. In the proposed scheme, the current control loop has been implemented using a hysteresis controller; whereas, the speed control loop has been implemented using a PI controller. The control scheme for IPMSM drive has been implemented in MATLAB/Simulink environment, and the transient performances of the drive have been scrutinized for different speed and load torque variations in order to demonstrate the efficacy of the drive control by way of model-in-the-loop (MIL), software-in-the-loop (SIL), and processor-in-the-loop (PIL) simulation techniques. A satisfactory control performance has been observed for all transient conditions.

The goal of this paper is to optimize the current loop of permanent magnet synchronous servo system. The current control loop form and the suitable parameters have been discussed first. Then the over modulation in PWM modulation has been introduced to improve the performance of current control loop, especially when the speed of motor is high. A prototype motor is designed and the experiment and simulation show that the feedback current follows the reference current exactly and fast. The over modulation can restrain the EMF, and improve the performance of current control loop, which provides a basis for realizing high performance permanent magnet synchronous servo system. The PCB design is also discussed to eliminate the EMI effects on the current loop.

Voltage source converters (VSCs) have emerged as the key components in modern power systems, facilitating efficient energy conversion and flexible power flow control. Understanding the fundamental circuit model of VSCs is essential for their accurate modeling and analysis in power system studies. A basic voltage source converter circuit model connected to an LC filter is essential because it lowers the harmonic distortions and enhances the overall power quality of the micro-grid. This guarantees a clean and steady power supply, which is necessary for the integration of multiple renewable energy sources and sensitive loads. A comprehensive methodology for developing a basic circuit model of VSCs, focusing on the key components and principals involved, is presented in this paper. The methodology includes the modeling of space vector pulse-width modulation (SVPWM) as well as the direct quadrature zero synchronous reference frame. Different design controls, including the design of current control loop in the S-domain, the design of the direct current (DC) bus voltage control loop in the S-domain, and the design of the alternating current (AC) voltage control loop in the S-domain, are explored to capture the dynamic behavior and control strategies of VSCs accurately. The proposed methodology provides a systematic framework for modeling VSCs, enabling engineers and researchers to analyze their performance and assess their impact on power system stability and operation. Future studies can be conducted by using case studies and simulation scenarios to show the efficiency and applicability of the developed models in analyzing VSC-based power electronics applications, including high-voltage direct current (HVDC) transmission systems and flexible alternating current transmission systems (FACTS). The significance of this work lies in its potential to advance the understanding and application of VSCs, contributing to more resilient and efficient power systems. By providing a solid foundation for future research and development, this study supports the ongoing integration of renewable energy sources and the advancement of modern electrical infrastructure.

Conventional front end converter (employing diode, thyristor) have several disadvantages like high harmonic current, low power factor. In this paper, single phase front end converter (FEC) employing IGBT as a switching device is reported. Various aspects of single phase FEC including, PLL design, modelling, controller design for current control and DC bus voltage control are studied. Second order generalized integrator - phase locked loop (SOGI-PLL) is employed to generate the unit vector for reference frame transformation. The system modeling is done in synchronous reference frame (SRF). Further, cascaded control scheme consisting of inner current-control loop and outer voltage-control loop is implemented for current and voltage control in SRF. Pole-zero cancellation and symmetric optimum methods are used to obtain the parameters of the current and voltage controllers. Unipolar Sine triangle pulse width modulation scheme is employed for switching the IGBT devices. Modelling and design approach of front end converter are presented in detail. The system is simulated on MATLAB Simulink to validate the design parameters and the converter shows good performance under the transient and steady state conditions. Unity power factor (UPF) on the grid side is achieved with bidirectional power flow capability.

A comparison of fuzzy self‐tuning (FST), sliding mode control (SMC) and conventional proportional–integral (PI) control methods is performed under unbalanced grid conditions using a bridgeless power factor correction (PFC) converter. The bridgeless PFC converter operates the correction of AC line current to obtain a DC output voltage without full bridge rectifier based on these control methods. These control methods generate the duty cycles to provide higher unity power factor and lower total harmonic distortion of input current, even if AC line voltage is distorted. This study focuses on the performance analysis of FST and SMC methods adaptation to the input current for the bridgeless PFC converter and comparing with the conventional PI controller. Although the SMC method is only used in the current control loop, the FST method is used in both current and voltage control loops for eliminating harmonics of input current and regulating of output voltage. The performance of control methods is evaluated with a TMS320F2812 digital signal processor. The simulation and experimental results are compatible with the limits for harmonic current emissions, IEC 61000‐3‐2 and show that the FST and SMC are better than the conventional PI control method and FST is superior to the SMC.

Servo drive systems require a fast dynamic response for position control applications. Conventional cascade control structure has sluggish response due to bandwidth limitations on speed and current control loop. To achieve a fast output response, model reference adaptive control methods can be used to remove the dynamics of inner control loops. In this paper, feed-forward signals are generated using model predictive control which is combined with the conventional cascade structure. Using this approach, a fast transient response and satisfactory tracking ability can be achieved. The proposed control configuration is verified by the simulation results.