Current sensorless model predictive torque control based on adaptive backstepping observer for PMSM drives

A novel adaptive backstepping observer is proposed and model predictive torque control (MPTC) strategy is considered for three-phase permanent magnet synchronous motor (PMSM) drives without any current sensor. Generally, instantaneous stator currents are required for successful operation of MPTC. If the stator current sensors fail, the most common technique for reconstructing stator currents mainly focuses on using information from a single current sensor in the DC-link of an inverter. Nevertheless, the existence of immeasurable regions in the output voltage hexagon results in that the three-phase currents will not be reliably detected since one or more of the active state vectors are not applied long enough to insure accurate measurements. In addition, the technique may suffer from the very noisy of DC-link current feedback. To avoid these drawbacks, making use of the technique of adaptive backstepping, a novel observer is proposed. The designed observer can be capable of concurrent estimation of stator currents and resistance under the assumption that rotor speed and inverter output voltage as well as DC-link voltage are available for measurement. Stability and convergence of the observer are analytically verified based on Lyapunov stability theory. In order to reduce the torque & flux ripples and improve drives control performance, MPTC strategy is employed. The proposed algorithm is less complicated and its implement is relatively easy. It can ensure that the whole drives system achieves satisfactory torque & speed control and strong robustness. Extensive simulation validates the feasibility and effectiveness of the proposed scheme

Design and Control of Electrical Motor Drives

Dear Colleagues, I am very happy to have this Special Issue of the journal Energies on the topic of Design and Control of Electrical Motor Drives published. Electrical motor drives are widely used in the industry, automation, transportation, and home appliances. Indeed, rolling mills, machine tools, high-speed trains, subway systems, elevators, electric vehicles, air conditioners, all depend on electrical motor drives.However, the production of effective and practical motors and drives requires flexibility in the regulation of current, torque, flux, acceleration, position, and speed. Without proper modeling, drive, and control, these motor drive systems cannot function effectively.To address these issues, we need to focus on the design, modeling, drive, and control of different types of motors, such as induction motors, permanent magnet synchronous motors, brushless DC motors, DC motors, synchronous reluctance motors, switched reluctance motors, flux-switching motors, linear motors, and step motors.Therefore, relevant research topics in this field of study include modeling electrical motor drives, both in transient and in steady-state, and designing control methods based on novel control strategies (e.g., PI controllers, fuzzy logic controllers, neural network controllers, predictive controllers, adaptive controllers, nonlinear controllers, etc.), with particular attention to transient responses, load disturbances, fault tolerance, and multi-motor drive techniques. This Special Issue include original contributions regarding recent developments and ideas in motor design, motor drive, and motor control. The topics include motor design, field-oriented control, torque control, reliability improvement, advanced controllers for motor drive systems, DSP-based sensorless motor drive systems, high-performance motor drive systems, high-efficiency motor drive systems, and practical applications of motor drive systems. I want to sincerely thank authors, reviewers, and staff members for their time and efforts. Prof. Dr. Tian-Hua Liu Guest Edito

Adaptive backstepping based nonlinear control of an interior permanent magnet synchronous motor drive

Permanent magnet synchronous machines (PMSM) have shown increasing popularity in recent years for industrial drive applications due to the recent developments in magnetic materials, power converters, and digital signal processors. In particular, Interior Permanent Magnet Synchronous Motor (IPMSM) drives are widely used in high performance drive (HPD) applications. Fast and accurate speed response and quick recovery of speed from any disturbances are essential. The control of a high performance permanent magnet synchronous motor drive for general industrial application has received wide spread interest of researchers. In this work, a novel speed and position control scheme for an IPMSM is developed based on a nonlinear adaptive control scheme. The vector control scheme is used to simplify control of the IPMSM. System model equations are represented in the synchronously rotating reference frame and provide the basis for the controller which is designed using the adaptive backstepping technique. Using Lyapunov’s stability theory, it is also shown that the control variables are asymptotically stable. The complete system model is developed and then simulated using MATLAB/Simulink software. Performance of the proposed controller is investigated extensively at different dynamic operating conditions such as sudden load change, command speed change, command position change and parameter variations. The results show the global stability of the proposed controller and hence found to be suitable for high performance industrial drive applications. The real time implementation of the complete drive system is currently underway

A Novel DTFC Based Efficiency and Dynamic Performance Improvement of IPMSM Drive

With the advancements in magnetic materials and semiconductor technology, permanent magnet synchronous motor (PMSM) is becoming more and more popular in high power industrial applications due to its high energy density, high power factor, low noise and high efficiency as compared to conventional AC motors. Field oriented vector control (VC) and direct torque and flux control (DTFC) are used for high performance drives. Among these two techniques DTFC is faster and simpler than that of conventional VC scheme as DTFC scheme doesn’t need any coordinate transformation, pulse width modulation and current regulators. The DTFC based motor drives utilizes hysteresis band comparators for both torque and flux controls. Both torque and flux are controlled simultaneously by the selection of appropriate voltage vectors from the inverter. However, DTFC suffers from high torque ripples due to discrete nature of control system and limited voltage vectors from the inverter. Torque ripples can be minimized by increasing the sector numbers of the DTFC scheme which increases the switching frequency of the inverter. Traditionally, researchers chose a constant value of reference air-gap flux to make the control task easy but it is not acceptable for high performance drives as the air-gap flux changes with the operating conditions and system disturbances. Furthermore, if the reference air-gap flux is maintained constant, it is not possible to control the motor over the wide speed range operation. Moreover, conventional six-sector based DTFC scheme suffers from high torque ripples, which is the major drawbacks to achieve high dynamic performance. Therefore, this thesis presents a novel eighteen-sector based DTFC scheme to achieve high dynamic performance with minimum torque ripples. In addition, the loss minimization algorithm (LMA) is incorporated with proposed DTFC scheme in order to improve the efficiency while maintaining high dynamic performance. This thesis further presents modified eighteen-sector based DTFC scheme to overcome the unbalanced voltage effects in any sector of conventional six-sector based system to improve the dynamic performance of the proposed system. This thesis also presents a novel sector determination algorithm to determine the sector number of the stator flux linkage vector which reduces the computational burden to the microprocessor. A five level torque hysteresis comparator based DTFC scheme is also proposed to reduce the torque ripple. Further, a backstepping based nonlinear controller is developed for IPMSM drive that achieves the lowest possible torque ripples in steady state. In this controller development, the control variable is motor electromagnetic developed torque and stator air-gap flux linkages similar to classical DTFC but the errors are forced to zero using backstepping process to get better dynamic performance. The effectiveness of the proposed systems is verified through the development of a simulation model using Matlab/Simulink. Performance of the proposed nonlinear controller is investigated extensively at different operating conditions such as sudden speed and load changes. Then the complete IPMSM drives, incorporating the proposed LMA and eighteen-sector based DTFC scheme and nonlinear controller with torque and flux as virtual control variables are successfully implemented in real-time using digital signal processor (DSP) board-DS1104 board for laboratory 5-hp motor. The effectiveness of the proposed control techniques are verified in both simulation and experiment at different operating conditions. It is found that, the nonlinear controller based IPMSM drive provides the best performance in terms of torque ripple among all the DTFC scheme developed in the thesis. The results show the robustness of the drive and it’s potentiality to apply for real-time industrial drive applications

Development and implementation of various speed controllers for wide speed range operation of IPMSM drive / by Md Muminul Islam Chy.

Despite many advantageous features of interior permanent magnet synchronous motor (IPMSM), the precise speed control of an IPMSM drive becomes a complex issue due to nonlinear coupling among its winding currents and the rotor speed as well as the nonlinearity present in the electromagnetic developed torque due to magnetic saturation of the rotor core particularly, at high speeds (above rated speed). Fast and accurate response, quick recovery of speed from any disturbances and insensitivity to parameter variations are some of the important characteristics of high performance drive system used in robotics, rolling mills, traction and spindle drives. The conventional controllers such as PI, PID are sensitive to plant parameter variations and load disturbance. For the purpose of obtaining high dynamic performance, recently researchers developed several non-linear as well as intelligent controllers. Most of the reported works on controller design of IPMSM took an assumption of d-axis stator current (i[subscript d]) equal to zero in order to simplify the development of the controller. However, with this assumption it is not possible to control the motor above the rated speed and the reluctance torque of IPMSM can not be utilized efficiently. Furthermore, this assumption leads to an erroneous result for motor at all operating conditions. In this thesis, some controllers are developed for the IPMSM drive system incorporating the flux-weakening technique in order to control the motor above the rated speed. A detailed analysis of the flux control based on various operating regions is also provided in this thesis. In order to get the optimum efficiency, an adaptive backstepping based nonlinear control scheme incorporating flux control for an IPM synchronous motor drive is taken into account at the design stage of the controller. Thus, the proposed adaptive nonlinear backstepping controller is capable of conserving the system robustness and stability against all mechanical parameters variation and external load torque disturbance. To ensure stability the controller is designed based on Lyapunov's stability theory. A novel fuzzy logic controller (FLC) including both torque and flux control is also developed in this work. The proposed FLC overcomes the unknown and nonlinear uncertainties of the drive and controls the motor over a wide speed range. For further improvement of the FLC structure, the membership function of the controller is tuned online. An integral part of this work is directed to develop an adaptive-network based fuzzy interference system (ANFIS) based neuro fuzzy logic controller. In this work, an adaptive tuning algorithm is also developed to adjust the membership function and consequent parameters. In order to verify the effectiveness of the proposed IPMSM drive, at first simulation model is developed using Matlab/Simulink. Then the complete IPMSM drive incorporating various control algorithms have been successfully implemented using digital signal processor (DSP) controller board-DSI104 for a laboratory 5 hp motor. The effectiveness of the proposed drive is verified both in simulation and experiment at different operating conditions. The results show the robustness of the drive and it's potentiality to apply for real-time industrial drive application. This thesis also provides through knowledge about development and various speed real-time applications of controllers for IPMSM drive, which will be useful for researchers and practicing engineers

PMSM Sensorless Speed Control Drive

Permanent magnet synchronous machines (PMSM) are very popular in many industrial applications such as in mechatronics, automotive, energy storage flywheels, centrifugal compressors, vacuum pumps, and robotics. This paper proposes Sensorless control for a PMSM speed drive which is based on a closed loop control system using a proportional and integral (PI) controller that is designed to operate in flux weakening regions under a constant torque angle. This Sensorless element was adopted for best estimating the PMSM rotor position based on its performance characteristics eliminating the need for speed sensors which are usually required in such control applications. To achieve this goal, a pulse width modulation (PWM) control scheme was developed to work in conjunction with a field oriented motor control drive using Simulink.This innovative control system was simulated assuming realistic circuit components to maximize the accuracy of the proposed model. Finally, simulation results obtained under different operation conditions at below and above the rated speed of the motor were presented and discussed in this paper

Torque Control

This book is the result of inspirations and contributions from many researchers, a collection of 9 works, which are, in majority, focalised around the Direct Torque Control and may be comprised of three sections: different techniques for the control of asynchronous motors and double feed or double star induction machines, oriented approach of recent developments relating to the control of the Permanent Magnet Synchronous Motors, and special controller design and torque control of switched reluctance machine

Performance Analysis Of IPMSM Drive Using Fuzzy Logic Controller Based Loss Minimization Algorithm (LMA)

This project presents an online loss-minimization algorithm (LMA) for a fuzzy-logic-controller (FLC)-based interior permanent-magnet synchronous-motor (IPMSM) drive to yield high efficiency and high dynamic performance over a wide speed range. LMA is developed based on the motor model. In order to minimize the controllable electrical losses of the motor and thereby maximize the operating efficiency, the d-axis armature current is controlled optimally according to the operating speed and load conditions. For vector-control purpose, FLC is used as a speed controller, which enables the utilization of the reluctance torque to achieve high dynamic performance as well as to operate the motor over a wide speed range. In order to test the performance of the proposed drive in real time, the complete drive is experimentally implemented using DSP board DS1104 for a prototype laboratory 5-hp motor. The performance of the proposed loss-minimization-based FLC for IPMSM drive is tested in both simulation and experiment at different operating conditions. A performance comparison of the drive with and without the proposed LMA-based FLC is also provided. It is found from the results that the proposed LMA and FLC-based drive demonstrates higher efficiency and better dynamic responses over FLC-based IPMSM drive without LMA. In this project, an online LMA-based speed-control scheme of IPMSM drive incorporating an FLC has been presented. The LMA was developed based on the motor model

Nonlinear adaptive control for robust wide speed range operation of IPMSM drives

Various applications, including robotics, spindle drives, machine tools, etc. rely on accurate, reliable controllers to deliver the required drive performance. With recent advances in magnetic materials and semiconductor technology, machines such as the permanent magnet synchronous machine (PMSM) family of ac drives have seen a rise in popularity, owing to the high power density, efficiency and relative longevity as compared to conventional ac motors. In particular, interior permanent magnet synchronous machines (IPMSM) are characterized by all the features of the PMSM family, with the additional possibility of improved efficiency due to rotor construction, making them ideal for critical applications with high performance demands. Notably, despite the advantageous aspects of PMSM motors in general, control of this class of ac machines is complex if full performance potential is to be realized. In order to achieve optimal efficiency while permitting wide speed range operation, it is crucial to design controllers that are capable of delivering this high performance. Due to the nonlinearity of magnetic flux distribution during operation, the parameters of the PMSM may vary significantly. Thus, a high performance controller must be capable of optimizing efficiency while maintaining excellent response characteristics from set-point or loading variations. As a result of the nonlinear flux distribution caused by rotor/stator magnetic field interactions, direct control of PMSM in the stator reference frame is not possible as the level of mathematical complexity renders it infeasible. Expression of the PMSM stator variables in the rotating rotor reference frame permits the effective decoupling of machine variables into velocity and torque control components. This is roughly analogous to separately excited direct current (DC) motors, where control of the rotor speed (field magnetization) and shaft torque (armature current) are decoupled as a function of the design. Analysis of the PMSM model in the rotating reference frame shows that the “d” and “q” axis currents are principally responsible for indirect air gap flux control and developed shaft torque, respectively. Traditional linear type control techniques based on proportional-integral-derivative (PID) controllers are able to achieve moderate success in controlling the PMSM family. The performance achieved is however typically within a narrow operational band and without the ability to adapt to parametric variation or optimize efficiency. This restriction makes PID type controllers non-ideal for more demanding applications that require highly accurate control and high efficiency regardless of load, temperature, machine age or operating environment. Therefore, this thesis presents a robust nonlinear control algorithm utilizing an adaptive back-stepping technique with flux control for optimizing developed torque and improved operational range. Further, global asymptotic stability of the proposed controller is assured through Lyapunov’s stability criterion in conjuncture with criterion supported by Barbalat’s lemma. The proposed control algorithm ensures that the machine operates at precise command speeds, coping with system uncertainties and disturbances, while reducing losses and enabling operation over a wide speed range. Simulation of the proposed system is carried out in MATLAB/Simulink, as well as in a cosimulation environment utilizing MATLAB/Simulink and PSIM. The first scenario implements an ideal mathematical system model with the controller in Simulink; whereas the second scenario uses PSIM to host the dynamic system model, with MATLAB/Simulink hosting the controller. This co-simulation permits rapid, accurate system analysis, by employing more accurate software models for switching elements, synchronous machine and any reactive elements not reflected in the basic mathematical model. Simulation results from both methods indicate excellent performance and robust operation, with excellent disturbance rejection. Real-time implementation of the system is realized utilizing the DS1104 digital signal processor (DSP) in conjuncture with an IPMSM commutated by a three-phase two-level insulated gate bipolar transistor (IGBT) inverter, with a direct current (DC) generator as dynamic load. Performance of the proposed controller have been verified through experimental implementation for a range of operating conditions

Online loss minimization based direct torque and flux control of IPMSM drive

With the advent of high energy rare earth magnetic material such as, third generation neodymium-iron-boron (NdFeB), permanent magnet synchronous motor (PMSM) is becoming more and more popular in high power industrial applications (e.g., high-speed railway) due to its advantageous features such as high energy density, stable parameters, high power factor, low noise and high efficiency as compared to the conventional ac motors. Over the years, vector control and direct torque and flux control (DTFC) techniques have been used for high performance motor drives. But, the DTFC is faster than that of conventional vector control as the DTFC scheme doesn't need any coordinate transformation, pulse width modulation (PWM) and current regulators. The DTFC utilizes hysteresis band comparators for both flux and torque controls. Most of the past researches on DTFC based motor drives mainly concentrated on the development of the inverter control algorithm with less torque ripple as it is the major drawback of DTFC. The torque reference value is obtained online based on motor speed error between actual and reference values through a speed controller. Traditionally, researchers chose a constant value of air-gap flux reference based on trial and error method which may not be acceptable for high performance drives as the air-gap flux changes with operating conditions and system disturbance. Efficient high performance drives require fast and accurate speed response to cope with disturbances and algorithm to minimize motor losses. However, if the reference air-gap flux is maintained constant it is not possible to control the motor losses. Therefore, this thesis presents a novel loss minimization based DTFC scheme for interior type PMSM drive so that the drive system can maintain both high efficiency and high dynamic performance. An online model based loss minimization algorithm (LMA) is developed to estimate the air-gap flux so that the motor operates at minimum loss condition while taking the general advantages of DTFC over conventional vector control. The performance the proposed LMA based DTFC for PMSM drive is tested in both simulation and real-time implementation at different operating conditions. The results verify the effectiveness of the proposed flux observer based DTFC scheme for PMSM drive