LQR-Based State Feedback for PMSM with Enhanced Dynamics via Integral Extended Modeling

In this thesis, a sensorless method for low and zero speed operation is proposed for a high-power medium-voltage pulse-width-modulated Current–Source-Converter (CSC)-fed Interior Permanent Magnet Motor (IPM) drive system. The proposed method is based on injection of a high-frequency (HF) pulsating sinusoidal signal into the estimated synchronous reference frame of the drive’s Field Oriented Control (FOC) scheme. The conventional FOC control scheme, low switching frequency, dc-link inductor and the inverter output three-phase filter capacitor of the medium-voltage high-power current-source drive present some challenges in the generation and design of the HF injection signal. To overcome the challenges, the FOC scheme is modified by introducing a modulation index control with a suitable dc-link current compensation to enhance the dynamic response of the injected signal and prevent any clamp in the injected signal. In addition, a Multisampling Space Vector Modulation (MS-SVM) method is proposed to prevent the distortion in the HF signal due to a low switching frequency to injected signal ratio. It is found that by using the proposed FOC scheme and multisampling modulation scheme, and proper design of the HF signal, an accurate rotor flux angle can be estimated for sensorless zero/low speed operation. Moreover, a novel input power factor compensation method is proposed for a high-power pulse-width-modulated Current-Source-Converter (CSC)-fed Permanent Magnet Synchronous Motor (PMSM) drive system. The proposed method is based on controlling the d-axis stator current component in the field-oriented control scheme of the drive system. The main feature of the proposed scheme is to compensate for the line-side power factor without the need for modulation index control in either the rectifier or the inverter. Simulation and experimental verification for various objectives are provided throughout the thesis. The results validate the proposed solutions for the main challenges of zero/low speed operation of sensorless Current-Source-Converter (CSC)-fed Permanent Magnet Synchronous Motor (PMSM) drive system.

The field-oriented control (FOC) strategy of a permanent magnet synchronous motor (PMSM) in a simplified form is based on PI-type controllers. In addition to their low complexity (an advantage for real-time implementation), these controllers also provide limited performance due to the nonlinear character of the description equations of the PMSM model under the usual conditions of a relatively wide variation in the load torque and the high dynamics of the PMSM speed reference. Moreover, a number of significant improvements in the performance of PMSM control systems, also based on the FOC control strategy, are obtained if the controller of the speed control loop uses sliding mode control (SMC), and if the controllers for the inner control loops of id and iq currents are of the synergetic type. Furthermore, using such a control structure, very good performance of the PMSM control system is also obtained under conditions of parametric uncertainties and significant variations in the combined rotor-load moment of inertia and the load resistance. To improve the performance of the PMSM control system without using controllers having a more complicated mathematical description, the advantages provided by reinforcement learning (RL) for process control can also be used. This technique does not require the exact knowledge of the mathematical model of the controlled system or the type of uncertainties. The improvement in the performance of the PMSM control system based on the FOC-type strategy, both when using simple PI-type controllers or in the case of complex SMC or synergetic-type controllers, is achieved using the RL based on the Deep Deterministic Policy Gradient (DDPG). This improvement is obtained by using the correction signals provided by a trained reinforcement learning agent, which is added to the control signals ud, uq, and iqref. A speed observer is also implemented for estimating the PMSM rotor speed. The PMSM control structures are presented using the FOC-type strategy, both in the case of simple PI-type controllers and complex SMC or synergetic-type controllers, and numerical simulations performed in the MATLAB/Simulink environment show the improvements in the performance of the PMSM control system, even under conditions of parametric uncertainties, by using the RL-DDPG.

FOC (field-oriented control) or vector control technique is used in permanent magnet synchronous motor to control the torque and field components of stator currents. To control the speed of the PMSM drive, the reference speed is taken as a input signal which is compared to actual speed of the motor and then speed controller generates a quadrature axis current signal which is used in vector control to control the torque and the flux. The simulation modelling of PMSM drive is done in MATLAB/Simulink. The measurements are taken of both simulated and hardware model of PMSM. The experiment results of the PMSM drive using FOC scheme are shown in this paper. PMSM operates in both constant torque as well as constant power region. Here, motor operation is done only in constant torque region. The experiment results indicate that the vector controlled-PMSM has improved speed stability still in a very low speed range.

Rotational Motion Control by Feedback with Minimum L1-Norm

The objective of this paper is to control the speed of Permanent Magnet Synchronous Motor (PMSM) over wide range of speed by consuming minimum time and low cost. Therefore, comparative performance analysis of PMSM on basis of speed regulation has been done in this study. Comparison of two control strategies i.e. Field oriented control (FOC) without sensor less Model Reference Adaptive System (MRAS) and FOC with sensor less MRAS has been carried out. Sensor less speed control of PMSM is achieved by using estimated speed deviation as feedback signal for the PI controller. Performance of the both control strategies has been evaluated in in MATLAB Simulink software. Simulation studies show the response of PMSM speed during various conditions of load and speed variations. Obtained results reveal that the proposed MRAS technique can effectively estimate the speed of rotor with high exactness and torque response is significantly quick as compared to the system without MRAS control system.

This paper examines the enhancement of Electric Vehicle (EV) Permanent Magnet Synchronous Motor (PMSM) drives through the integration of Field-Oriented Control (FOC) with Model Predictive Control (MPC). The study aims to achieve high precision and dynamic response for PMSM drives under diverse operating conditions. FOC provides good control capability over full torque and speed ranges. MPC is an optimal control technique in which the calculated control actions minimize a cost function for a constrained dynamic system. The theoretical framework combines FOC and MPC principles, utilizing MPC's predictive capabilities to optimize d-q current references in real-time. The methodology encompasses the design and implementation of an MPC technique integrated with FOC, with key objectives including minimising torque ripples, maintaining vehicle stability through robust control loops, and optimising PMSM drive performance across a wide speed range of EV. Different types of torque control methodologies, such as PI Controller and Voltage Vector Control for PMSM Control, can be applied to an electric vehicle. The results indicate significant improvements in torque ripple reduction, dynamic response, and disturbance rejection, demonstrating the robustness and adaptability of the proposed control system compared with the PI Controller. This approach effectively addresses key challenges and signifies advancements over traditional control methods, contributing to the field of electric vehicle control systems.

In the conventional discrete Field Oriented Control (FOC) system, the performance of current regulator is limited in transient, due to the existence of numerical delay such as current sampling and the updating of Pulse-Width Modulation (PWM) duty-cycle. This paper proposed a discrete predictive current control based on deadbeat control in the rotor frame to improve the performance of current loop. Therefore the numerical delays in conventional FOC system are eliminated by the algorithm. Simulation and experiment results show that the PMSM (Permanent Magnet Synchronous Motor) deadbeat predictive current control improves efficiently both the dynamic performance and steady-state precision of the current loop.

This paper proposes a comparison study focusing on the dynamic response and tracking accuracy for the induction motor drive system influenced by the controller design methods. Pole-zero cancellation (PZC) and pole placement (PP) methods are commonly used to define the controller gains for motor drive systems, and both methods are verified in this paper. The bandwidth of controllers for both methods is set equally based on the field-oriented control strategy, which consists of current and speed control loops. Furthermore, the test conditions are defined to examine the drive system performance, i.e., i) load torque rapidly changes with the maintained speed and ii) speed changes in no-load and with-load torque conditions to validate the current and speed control loops, respectively. The validation of the drive system performance influenced by the controller design methods is demonstrated by simulation results.

ABSTRACTDue to the challenges in determining the parameters of traditional controllers, achieving efficient performance during the control process remains difficult. To improve control performance, this paper presents a novel speed control scheme based on the parameter tuning of a linear quadratic regulator (LQR). The proposed control approach begins by establishing the speed state error in the rotor reference coordinate system, followed by the design of a custom parameter switching surface and control law. LQR theory is then utilized to adjust the state‐space equations, allowing for the calculation of the parameters for the tracking error function and control law. This controller incorporates both the speed tracking error and the integral of the speed tracking error. Simulations and experiments are designed to validate the effectiveness of the proposed control scheme. Comparison results with traditional control methods, such as PI control based on motor parameters, sliding mode control, and PI control with state feedback, indicate that the proposed LQR parameter tuning control scheme excels in the speed control of PMSM.

This article presents the sensorless control of a PMSM based on the FOC (Field Oriented Control) strategy and on PFC (Power Factor Correction), where the rotor speed is provided by speed observers. It presents the block structure of the PFC together with the numerical simulations achieved in Matlab/Simulink, on the improvement of the PF (Power Factor) of the supply circuit. It also presents the block structures of the FOC strategy and of the back-EMF (back electromotive force) sliding mode, MRAS (Model Reference Adaptive System), and PLL (Phase Locked Loop) type observers. The numerical simulations show the superiority of rotor speed estimation when using the back-EMF sliding mode observer compared to the rotor speed estimate provided by MRAS and PLL observers.

This study compares Field-Oriented Control (FOC) and trapezoidal control techniques for Permanent Magnet Synchronous Motors (PMSMs) in modern industrial variable-speed applications. Traditionally, variable-speed applications have relied on DC machines, which have inherent drawbacks such as increased maintenance, spark losses, higher inertia, and overall higher costs. This FOC has emerged as a sophisticated method that enables independent control of torque and magnetization flux in AC motors, allowing for precise regulation of torque and speed tailored to the motor's electromagnetic state. FOC leverages Sinusoidal Pulse-Width Modulation (SPWM) and Space Vector Pulse Width Modulation (SVPWM) techniques to enhance DC voltage utilization and minimize switching and harmonic losses. In contrast, the paper presents a detailed model of a PMSM drive system based on electronic components rather than standard mathematical blocks, leading to more realistic simulation results. All simulation modules, including the inverter and PWM generator, were custom-built, allowing for performance comparison under varying speed and torque conditions. Brushless DC (BLDC) motors, which are typically categorized as PMSMs with trapezoidal back-EMF waveforms, have gained traction due to their simplicity and cost-effectiveness. The trapezoidal control technique, also known as six-step commutation, simplifies the control process by aligning motor phase switching with the rotor position, resulting in a quasi-square-wave current. However, this method introduces torque ripple and presents control challenges, particularly in low-speed applications. Given the rising economic constraints and stringent governmental standards, there is an increasing demand for efficient, low-interference, and adaptable electrical systems. This study demonstrates that FOC provides a more robust and efficient solution for high-performance applications than the trapezoidal control technique in PMSMs.

This paper deals with the performance analysis of the field oriented control (FOC) of permanent magnet synchronous motor (PMSM) drive with a PID (proportional plus integral plus derivative) in DC link voltage control and fuzzy PID for speed control in closed loop operation. A mathematical model of the PMSM drive has been developed by considering each accessories of the model to analyze both the steady state and transient performances of the PMSM drive system. The current controlled inverter feeding power to the PMSM motor is powered from a PWM current controlled converter. The advantages of the integrated PMSM drive are demonstrated. The PID voltage control takes care of the constant DC link voltage to feed the inverter. The fuzzy controller provides a better response to the drive system specially in the steady state condition. The state space model developed in terms of derivatives of winding currents, DC link voltage, supply currents, rotor speed, and rotor position are simulated to obtain the required information. The study also examines the effectiveness of the PMSM drive under steady state and transient conditions for different parameter variation.

This paper represents a comprehensive analysis of Field-Oriented Control (FOC) technique for Permanent Magnet Synchronous Motors (PMSM) employing Space Vector Modulation (SVM) and Sinusoidal Pulse Width Modulation (SPWM). A comprehensive dynamic model of the PMSM is created, integrating mechanical dynamics and d-q axis equations to construct proportional integral (PI) controllers for speed and current management. The performance of SPWM and SVM is studied under two operational modes: constant speed and constant torque, focusing on transient response, steady-state accuracy, and harmonic distortion. The performance of both modulation strategies is evaluated using a Proportional-Integral (PI) controller designed and implemented in MATLAB/Simulink. Simulation results show that compared to SPWM, SVM achieves superior dynamic performance, with faster settling time, lower torque ripple, and improved DC bus voltage utilization. SVM reduces fluctuations in speed in the constant torque mode, but SPWM shows more harmonic distortion in the stator currents. The study underscores the importance of modulation strategy selection in optimizing PMSM drives for electric Vehicles.

<div class="section abstract"><div class="htmlview paragraph">Electromagnetic suspension systems have increasingly gained widespread attention due to their superiority in improving ride comfort while providing fast response, excellent controllability and high mechanical efficiency, but their applications are limited due to the accuracy of the underlying control actuation tracking. For addressing this problem, this study presents a novel hierarchical control strategy for an electromagnetic active suspension (EMAS) system equipped with an electromagnetic actuator (EMA) structure. The structure of the EMA device and the working principle of the motion conversion model are introduced in detail first, and the motion conversion equation is derived based on the force-torque relationship. Based on this, a linear quadratic regulator (LQR) control method is proposed to be applied to a half-vehicle suspension system to improve the vibration isolation performance of the vehicle and ensure the ride comfort. Then, the underlying layer control of the permanent magnet synchronous motor (PMSM) based on field-oriented control (FOC) is adopted to tracking the active control forces generated by the upper LQR controller. Immediately afterwards, the EMA converts the torque generated by the motor into vertical forces acting on the suspension through rational synergies between the upper LQR controller and the underlying motor controller, which ultimately achieves active control of the vehicle suspension system. The simulations are carried out from the perspective of the half-vehicle integrated with the EMA, which demonstrate that the proposed EMAS system has greatly reduced vehicle vertical and pitch accelerations compared to the conventional passive suspension, significantly improving the ride comfort and vibration isolation effect on external excitation.</div></div>

In this paper, a power factor corrected Permanent Magnet Synchronous motor (PMSM) drive is discussed in detail. The wide variety of applications of PMSM drives makes it necessary to achieve fast and reliable drive control system design. This paper presents an analytical modeling of Surface Permanent magnet Synchronous motor (SPMSM) and Interior Permanent magnet Synchronous motor (IPMSM). A PI-controller based closed-loop Volts/hertz (V/F) controller is designed. It is based on Field Oriented Control (FOC) algorithm and operates in constant torque region. The controller is designed to ensure that the three phase IPMSM is operated close to unity power factor for wide speed range. IPMSM is designed and modeled using MATLAB/Simulink environment. The performance of the motor is evaluated in terms of power factor, total harmonic distortion and efficiency. Furthermore, a comparative analysis is done to validate the efficacy of IPMSM.