Torque Ripple Minimization Control Research Articles

Torque Ripple Minimization Control Strategy in Synchronous Reluctance Machines

Torque smoothness is an essential requirement for high-performance motor drive applications. Synchronous reluctance machines (SyRM) have high torque ripple due to non-linear magnetic circuit and saturation. Typically, in Permanent magnet machines the active torque ripple compensation is achieved by injecting a compensating ripple current in the <i>q-axis</i>. For SyRM, the current injection method for active torque ripple cancellation can be used in both the <i>d-axis</i> and <i>q-axis</i>. However, the saturation of the motor parameters with the changing current can result in varied performance between the two methods. This paper evaluates the effectiveness of both of these methods for torque ripple cancellation. For evaluation, the impact of parameter saturation with ripple current injection on the <i>d-axis</i> and the <i>q-axis</i> is studied. The mathematical conclusions obtained are evaluated by both the simulation and the experimental results performed on a 4 pole 1200W Synchronous reluctance machine.

Integration of Interturn Fault Diagnosis and Torque Ripple Minimization Control for Direct-Torque-Controlled SPMSM Drive System

This article proposes an integration method for interturn fault diagnosis and torque ripple minimization control of direct-torque-controlled surface-mounted permanent magnet synchronous machine (SPMSM) drive system without requiring the specific fault severity (short-circuited turn ratio, current). In this method, the interturn fault is detected and located based on the amplitude and initial phase angle of the zero-sequence voltage component (ZSVC). Both the torque injection and the improved flux observer are applied to reduce the torque ripple caused by the interturn fault. Furthermore, the torque injection and the improved flux observer are directly calculated by using the already obtained amplitude and initial phase angle of the ZSVC during the fault diagnosis process, without requiring the specific values of short-circuited turn ratio and fault current. The experimental results validate the effectiveness of the proposed integration method for the direct-torque-controlled SPMSM drive system.

Improved Iterative Learning Direct Torque Control for Torque Ripple Minimization of Surface-Mounted Permanent Magnet Synchronous Motor Drives

This article presents an improved iterative learning direct torque control (IL-DTC) to remarkably minimize the torque ripples for a surface-mounted permanent magnet synchronous motor (SPMSM) drive. Unlike the conventional IL-DTC, the proposed IL-DTC significantly attenuates the torque ripples by effectively suppressing the repetitive disturbances using the speed and load torque compensating terms in the improved error dynamics via the improved feedback control terms and iterative learning control terms. Further, it has a simple structure and fast dynamic response due to the direct control of the torque and flux. The stability is verified through the convergence of speed errors to zero as the iteration index goes to infinity. The comparative results via MATLAB/Simulink and a prototype SPMSM test-bed with TI-TMS320F28335-DSP demonstrate the improved control performance (e.g., less torque ripples, faster transient response, smaller overshoot/undershoot, and smaller steady-state error) over the conventional IL-DTC under critical load/speed conditions with severe model parameter uncertainties.

Fast and Comprehensive Online Parameter Identification of Switched Reluctance Machines

The switched reluctance machine has been an attractive candidate for many applications owing to its simple design and low construction costs, without the use of permanent magnets. However, the double saliency of its stator and rotor poles results in noise-causing torque ripples. And although advanced torque ripple minimization control techniques exist, they rely on modeling the machine, which in turn requires specialized offline experimental setups or online (during operation) parameter identification techniques. To date, existing online techniques are iterative without proof of convergence, do not provide all model parameters, and/or rely on a priori information that can change after the machine is commissioned. In this work, an online parameter identification method is developed with a new empirical model of its flux linkage and electromagnetic torque, to provide a complete nonlinear model of the machine. With two seconds of data collected online, all electrical and mechanical parameters are identified using a non-iterative algorithm, and so it does not pose a risk of divergence. Therefore, parameter identification can be reliably and frequently carried out at different operating conditions as the machine ages for diagnostics. Also, the resulting model is designed to be used by advanced torque ripple minimization control techniques. The implementation procedure is detailed along with simulation results to demonstrate its efficacy.

Adaptive Control for Torque Ripple Minimization in PM Synchronous Motor (Dept.E)

paper presents two methods for designing special purpose controllers for permanent magnet synchronous motor. The main target of the designed controllers is to reduce torque ripples of this type of motors. The first proposed adaptive method is based on two loop controllers (current controller and speed controller) in addition to using space vector pulse width modulation to maximize fundamental component of torque. The second proposed method is based on PI current controllers enabling tracking of quadrature current command values. Simulation results of the suggested adaptive controller are compared with that of the PI controller. Comparative analysis proves the effectiveness of the suggested adaptive controller than the classical PI one according to ripple reduction as well as dynamic response. Moreover, the suggested adaptive controller when compared with other controllers shows great success in torque ripples reduction, enabling speed tracking while minimizing the torque ripple. Keywordsreference adaptive system, PM synchronous motor, torque control.

Torque Ripple Minimization Control in SRM Based on Magnetizing Curve Model Considering Mutual Coupling

In order to minimize torque ripple in a switched reluctance motor (SRM), various control methods have been proposed. One such method is current profiling control based on a mathematical motor model concerned with the relationship between torque position and current, which can be derived from measured magnetizing curves. However, current profiling control faces issues with an increase in torque ripple at the current overlapping region depending on the load condition. In this study, through magnetic analysis using 2D-FEA and mathematical analysis based on a test SRM (four-phase, 400W, and 8/6 pole configuration), the reason why the torque ripple increases is revealed, and a modified torque-position-current model considering mutual coupling is proposed for better control of torque ripple minimization. Experimental studies on torque ripple minimization using the test motor show that the proposed current profiling control offers better torque ripple control performance.

Speed Harmonic Based Decoupled Torque Ripple Minimization Control for Permanent Magnet Synchronous Machine With Minimized Loss

This article proposes a closed-loop decoupled current control for torque ripple minimization (TRM) of permanent magnet synchronous machines (PMSMs) by using the speed measurements. In the proposed control, a decoupled scheme is developed to control the harmonic currents for TRM, in which the control of phase angle and magnitude is decoupled to simplify the controller design. The decoupled scheme consists of two PI controllers and one control rule: one PI is responsible for phase angle control, the other is responsible for magnitude control, and the control rule is responsible for coordinating the two PIs for TRM. The harmonic currents can produce additional loss, and thus this paper derives the optimal condition for TRM with minimized loss. With the derived condition, one can control q -axis current and calculate d -axis current from the derived condition, which can minimize the torque ripple with minimized loss and simplify the control structure. The proposed decoupled approach is evaluated with extensive experiments and comparative study on a laboratory PMSM drive.

Torque Ripple Minimization for Inter-Turn Short-Circuit Fault Based on Open-Winding Five Phase FTFSCW-IPM Motor for Electric Vehicle Application

High reliability and fault-tolerant operation capability are the application requirements of electric vehicles(EVs). In case of the drive system suffering from inter-turn short-circuit (ITSC) fault, it is necessary to avoid the aggravation of the fault and ensure the normal output performance, this paper proposed a torque ripple minimization control strategy for ITSC fault based on the open-winding (OW) five phase fault tolerant fractional slot concentrated winding interior permanent magnet (FTFSCW-IPM) motor drive system with common DC bus. Once the ITSC fault is detected, the fault phase is active open-circuit (OC) (null the current of the normal part in the fault phase) and connected to a voltage sensor. In this way, the torque ripple minimization control strategy can deal with the OC fault and ITSC fault. For the OC fault, the equal amplitude phase current modulation strategy is adopted based on the carrier-based pulse width modulation (CPWM). For the ITSC fault, this paper proposed a feedforward compensation approach to eliminate the influence of the short-circuit loop current. The novelty of the proposed method is that the compensation can be real-time estimated using the zero-sequence voltage (ZSV) and zero-sequence current (ZSC), even the ITSC level changes. Simulation and experimental results demonstrate the effectiveness and feasibility of the proposed method.

On-Line Inter-Turn Short-Circuit Fault Diagnosis and Torque Ripple Minimization Control Strategy Based on OW Five-Phase BFTHE-IPM

This paper proposed an on-line inter-turn short-circuit (ITSC) fault diagnosis approach by observing the dc component in the torque deviation for the open-end winding (OW) five-phase brushless fault-tolerant hybrid-excitation interior permanent magnet motor (BFTHE-IPM). To eliminate the impact of ITSC fault on torque and guarantee a disturbance-free operation, the strategy of torque ripple minimization is proposed, in which the virtual direct-quadrature axis current feedforward compensator is adopted. Moreover, the compensation is obtained by measuring the zero-sequence current without calculating short-circuit turns ratio and short-circuit current. Therefore, computational quantity and complexity of the algorithm are greatly reduced. Simulation and experimental results verify the effectiveness of the proposed method.

Torque Ripple Minimization Control Technique of High-Speed Single-Phase Brushless DC Motor for Electric Turbocharger

The electrification of a forced induction system (FIS) has emerged as a feasible solution for low greenhouse gas emission and high fuel economy in passenger cars and light-duty trucks. A high-speed electric motor in conjunction with the conventional FIS has numerous benefits including better transient response and higher engine output power. A single-phase brushless dc (BLDC) motor possesses a number of attractive features for this application including high efficiency, low cost, robustness, and high-speed operation capability. However, it generates higher torque ripple than that of three-phase BLDC motor due to the lack of alternate phases and phase current distortion. This paper proposes a new torque ripple minimization control technique, which has a linearly decreasing reference voltage to regulate phase current. The analytical estimation and experimental results verify that the new control technique reduces the motor vibration while improving the maximum speed and the efficiency of the motor drive.

Fourier Series Learning Control for Torque Ripple Minimization in Permanent Magnet Synchronous Motors

A new Fourier Series Learning Controller (FSLC) for velocity control on a Permanent Magnet Synchronous Motor (PMSM) is proposed and implemented. An analysis of the error convergence for the FSLC is presented, and the update law for the Fourier series coefficients is specified. The field-oriented control method is used as a basic element to implement three different controllers for a PMSM. The performance of the FSLC is compared with two control methods, a classical PI (Proportional Integral) controller and an artificial neural network controller. The periodic nature of torque ripple in PMSMs is considered as a periodic disturbance, which must be compensated by the controller. With the FSLC implementation, a substantial reduction of the velocity ripple is obtained. Furthermore, a higher speed of learning is achieved with the FSLC in comparison with the artificial neural network.

Intelligent Control for Torque Ripple Minimization in Combined Vector and Direct Controls for High Performance of IM Drive

In Conventional Combined Vector and Direct Controls (VC-DTC) of induction motor, stator current is very rich in harmonic components. It leads to high torque ripple of induction motor in high and low speed region. To solve this problem, a control method based on the concept of fuzzy logic approach is used. The control scheme proposed uses stator current error as variable. Through the fuzzy logic controller rules, the choice of voltage space vector is optimized and then torque and speed are controlled successfully with a less ripple level in torque response, which improve the system's performance. Simulation results trough MATLAB/SIMULINK® software gave results that justify the claims.

Adaptive Control for Torque Ripple Minimization in PM Synchronous motors

paper presents two methods for designing special purpose controllers for permanent magnet synchronous motor. The main target of the designed controllers is to reduce torque ripples of this type of motors. The first proposed adaptive method is based on two loop controllers (current controller and speed controller) in addition to using space vector pulse width modulation to maximize fundamental component of torque. The second proposed method is based on PI current controllers enabling tracking of quadrature current command values. Simulation results of the suggested adaptive controller are compared with that of the PI controller. Comparative analysis proves the effectiveness of the suggested adaptive controller than the classical PI one according to ripple reduction as well as dynamic response. Moreover, the suggested adaptive controller when compared with other controllers shows great success in torque ripples reduction, enabling speed tracking while minimizing the torque ripple. Keywordsreference adaptive system, PM synchronous motor, torque control.

Torque ripple minimization control of permanent magnet synchronous motors for EPS applications

This paper identifies a control method used to reduce torque ripple of a permanent magnet synchronous motor (PMSM) for an electric power steering (EPS) system. NVH (Noise Vibration Harshness) is important for safe and convenient driving. Vibration caused by motor torque is a problem in column type EPS systems. Maintaining a very low torque ripple is one solution that allows for smoother steering. Theoretically, it is possible to design and drive the motor without torque ripple. However, in reality, a PMSM system torque ripple is caused by the motor itself (saturation in the iron core and EMF distortion) and the imperfect driver. This paper analyzes torque ripple of a PMSM system, and an advanced PMSM control method for the column typed EPS system is presented. Results of the analysis indicate that the compensation current is needed in order to minimize torque ripple when a PMSM is driven.