Torque Ripple Minimization for a Permanent Magnet Synchronous Motor Using a Modified Quasi-Z-Source Inverter

This paper presents a torque ripple minimization method for a permanent magnet synchronous motor (PMSM) drive system that utilizes a modified quasi-Z-source (qZS) inverter. The proposed modified qZS network is designed by adding an extra switching device to the conventional qZS topology and provides a wider range of capabilities for inverter input voltage control, e.g., both step-up and step-down operations. It also allows for modification of the traditional switching sequence selection scheme when using the space vector modulation (SVM) for switching. The provided flexibilities are leveraged to develop a control system that minimizes the torque ripples during PMSM operation while satisfying conventional control objectives such as shaft speed control. The control system is comprised of an input voltage optimization subsystem with the goal of torque ripple minimization, which provides the reference for a cascaded modulated model predictive control subsystem for the modified qZS network control, and a motor side predictive control subsystem. The control system employs a new switching sequence selection scheme for SVM modulation to further reduce PMSM torque ripples. Experimental results are provided to validate the theoretical outcomes

Critical Aspects of Electric Motor Drive Controllers and Mitigation of Torque Ripple - Review

Electric vehicles (EVs) are playing a vital role in sustainable transportation. It is estimated that by 2030, Battery EVs will become mainstream for passenger car transportation. Even though EVs are gaining interest in sustainable transportation, the future of EV power transmission is facing vital concerns and open research challenges. Considering the case of torque ripple mitigation and improved reliability control techniques in motors, many motor drive control algorithms fail to provide efficient control. To efficiently address this issue, control techniques such as Field Orientation Control (FOC), Direct Torque Control (DTC), Model Predictive Control (MPC), Sliding Mode Control (SMC), and Intelligent Control (IC) techniques are used in the motor drive control algorithms. This literature survey exclusively compares the various advanced control techniques for conventionally used EV motors such as Permanent Magnet Synchronous Motor (PMSM), Brushless Direct Current Motor (BLDC), Switched Reluctance Motor (SRM), and Induction Motors (IM). Furthermore, this paper discusses the EV-motors history, types of EVmotors, EV-motor drives powertrain mathematical modelling, and design procedure of EV-motors. The hardware results have also been compared with different control techniques for BLDC and SRM hub motors. Future direction towards the design of EV by critical selection of motors and their control techniques to minimize the torque ripple and other research opportunities to enhance the performance of EVs are also presented.publishedVersio

Speed Ripple Reduction of Direct-Drive PMSM Servo System at Low-Speed Operation Using Virtual Cogging Torque Control Method

This paper presents a virtual cogging torque (VCT) control method to reduce the speed ripple of direct-drive permanent magnet synchronous machine (DD-PMSM) servo system under low-speed conditions. Compared with other factors, at low speeds, the cogging torque is the main factor that deteriorates the drive performance, even induces speed oscillations. Especially in this paper, due to volume limitation, the cogging torque is designed larger than normal one in order to remove the need of brake. Based on the model of PMSM, the cause and effect of the cogging torque are analyzed. Inspired by the characteristic of cogging torque, the VCT control method is proposed and investigated to significantly reduce the speed ripple at low speeds. The main idea of this proposed control method is to produce a proper virtual cogging torque and continuously move the corresponding virtual stable equilibrium point to drive the rotor smoothly. In addition to the principle of this control method, its analysis and implementation are studied as well. Simulation and experimental results from the prototype demonstrate that the proposed control method is correct and valid, and it is simple and effective to smooth the speed at low-speed operations

Disturbance/uncertainty estimation and attenuation techniques in PMSM drives–a survey

This paper gives a comprehensive overview on disturbance/uncertainty estimation and attenuation (DUEA) techniques in permanent magnet synchronous motor (PMSM) drives. Various disturbances and uncertainties in PMSM and also other alternating current (AC) motor drives are first reviewed which shows they have different behaviors and appear in different control loops of the system. The existing DUEA and other relevant control methods in handling disturbances and uncertainties widely used in PMSM drives, and their latest developments are then discussed and summarized. It also provides in-depth analysis of the relationship between these advanced control methods in the context of PMSM systems. When dealing with uncertainties,it is shown that DUEA has a different but complementary mechanism to widely used robust control and adaptive control. The similarities and differences in disturbance attenuation of DUEA and other promising methods such as internal model control and output regulation theory have been analyzed in detail. The wide applications of these methods in different AC motor drives (in particular in PMSM drives) are categorized and summarized. Finally the paper ends with the discussion on future directions in this area

A fractional delay variable frequency repetitive control for torque ripple reduction in PMSMs

Based on the internal model principle, repetitive controller (RC) is capable to reduce periodic torque ripple by generating a compensating action that consequently need to be synchronized with the original ripple. However, the synchronization is difficult to achieve using the conventional RC when the sampling frequency is not integer multiple of the speed (known as fractional delay issue), or when the speed varies widely. To solve this problem, this paper presents a fractional delay variable frequency torque ripple reduction method for PMSM drives using the combination of angle-based RC and deadbeat current control (DBCC). Four aspects of innovations are included in the proposed control to improve the synchronization. The experimental results show that the proposed control can effectively reduce torque ripple even during speed and load transient

Current and voltage shaping method via modified d–q transformation for the torque ripple compensation in PMSMs

This study deals with a novel control strategy for permanent magnet synchronous machines (PMSMs) to incorporate disturbance compensation features in the existing current controller maintaining at the same time the integrity of the reference tracking performances. The torque produced by a PMSM arises from the interaction of stator currents and rotor magnetic flux, therefore an intrinsic disturbance is propagated to the output, in case the flux is not perfectly sinusoidal. In particular, the authors focus is to propose the effective correction of undesired harmonic effects generated on the torque from the non-ideal machine rotor. With the knowledge of the back electromagnetic force waveform, it is possible to determine the current waveforms necessary to produce a smooth torque in normal operation and through model-base considerations, the required voltage harmonic waveforms are also computed. The method is also extended to the flux weakening operation of the machine. The analytical solutions found are used in place of the classical αβ/dq transformations, without modifying the field-oriented control performance of the main controller. The effectiveness of the proposed control scheme is verified by means of test-bench measurement

A variable frequency angle-based repetitive control for torque ripple reduction in PMSMs

This paper presents a novel method for torque ripple reduction in PMSM drives at variable speed, using a combination of angle-based repetitive control and deadbeat current control. Based on the internal model principle, repetitive control is capable to reduce periodic torque ripple by generating a compensating action that consequently need to be synchronized with the original ripple. The time to angle, angle to time conversions for repetitive control, which improve both the stability and the performance when the sampling frequency is not integer multiple of the speed, are presented. A transient detection strategy is also developed to allow a stable torque ripple reduction even during speed and load changes

Permanent-Magnet Synchronous Machine Drives

The permanent-magnet synchronous machine (PMSM) drive is one of best choices for a full range of motion control applications. For example, the PMSM is widely used in robotics, machine tools, actuators, and it is being considered in high-power applications such as industrial drives and vehicular propulsion. It is also used for residential/commercial applications. The PMSM is known for having low torque ripple, superior dynamic performance, high efficiency and high power density. Section 1 deals with the introduction of PMSM and how it is evolved from synchronous motors. Section 2 briefly discusses about the types of PMSM. Section 3 tells about the assumptions in PMSM for modeling of PMSM and it derives the equivalent circuit of PMSM. In Section 4, permanent magnet synchronous motor drive system is briefly discussed with explanation of each blocks in the systems. Section 5 reveals about the control techniques of PMSM like scalar control, vector control and simulation of PMSM driven by field-oriented control using fuzzy logic control with space vector modulation for minimizing torque ripples. PMSM control with and without rotor position sensors along with different control techniques for controlling various parameters of PMSM for different applications is presented in Section 6

Torque pulsations minimization in PM synchronous motor drive

Master'sMASTER OF ENGINEERIN