Torque Ripple Analysis Research Articles

Finite Element Analysis of Cogging Torque and Torque Ripple of Brushless DC Motor

Finite Element Analysis of Cogging Torque and Torque Ripple of Brushless DC Motor

Dynamic Modeling Approach in View of Vector Control and Behavior Analysis of a Multi-Three-Phase Star Permanent Magnet Synchronous Motor Drive

In order to fully utilize the control degrees of freedom of a multi-three-phase-star smooth-pole permanent magnet synchronous motor (PMSM), this paper first develops a modeling approach using a new matrix transformation method. The proposed transformation produces decoupled and independent star windings, removing the inductive couplings and preserving the model and torque control’s consistency as the number of phases increases. The model, together with a new vector control scheme, is superior for studying the effect of the winding phase angle shift on motor performance. Based on a numerical simulation, this paper focuses on the quality analysis of phase currents, non-sequential currents, and torque ripple with different phase angles for double- and triple-star PMSM drives. The control of a triple-star PMSM is validated, and the behavior analysis is investigated by OPAL-RT.

Cogging torque and torque ripple analysis of permanent magnet flux-switching machine having two stators

Cogging torque and torque ripple analysis of permanent magnet flux-switching machine having two stators

An experimental study of the sensorized strain wave gear RT1-T and its capabilities for torque control in robotic joints.

The idea of sensorizing a strain wave gear to measure the transmitted torque has been reported since the 1980s. The strain in the elastic flex spline is typically measured by strain gages attached to it. The resulting voltages relate to the transmitted torque in the gear. However, periodic inaccuracies in the measured torque signal (sensing ripple), resulting from positioning inaccuracies of strain gages on the flex spline, prevented this technology from being used outside a lab environment. Regardless of these difficulties, measuring the torque directly in the strain wave gear would bring many advantages, especially in robotic applications, where design space is highly limited. Traditionally, robotic joints are equipped with link-sided torque sensors, which reduce the available design volume, lower the joint stiffness, and require complex cable routing. This paper presents an experimental study of a novel sensorized strain wave gear named RT1-T, which was developed by Schaeffler Technologies. The study was implemented on a joint testbed, including a high-resolution reference torque sensor at the link side. In addition to the measurement accuracy and linearity, a torque ripple analysis is performed. The joint torque control capabilities are determined along dynamic trajectories and compared to the performance achieved with a link-sided reference sensor. The sensor employed in the testbed has a static torque error of 0.42 Nm and an average closed-loop torque control error of 0.65 Nm above the reference sensor.

Torque Ripple Analysis and Reduction of Interior Permanent Magnet Synchronous Motors

Torque Ripple Analysis and Reduction of Interior Permanent Magnet Synchronous Motors

Analysis and Approximation of THD and Torque Ripple of Induction Motor for SVPWM Control of VSI

This article presents a harmonic analysis of the stator currents of a squirrel-cage induction motor fed by a voltage source inverter with PWM space vector control (SVPWM). The influence of PWM switching frequency and dead time (dead band) of controlled transistors on THD and electromagnetic torque ripple is shown. The aim is to determine the lowest switching frequency of the transistors for which the drive will operate correctly. Characteristics were determined as functions in the form of THD (fPWM), where the least square approximation was used for stator current measurements when the PWM switching frequency was changed. The approximations were realized for simulation and experimental results. To clarify the results, the operation of hardware PWM circuits in microcontrollers is analyzed.

Analysis of Torque Ripple in V-Shape Interior Permanent Magnet Machine Based on General Airgap Field Modulation Theory

This paper proposes a novel torque ripple model of V-Shape interior permanent magnet (IPM) synchronous machine based on the general field modulation theory (GAFMT). Firstly, the magnetic field modulation behavior of a 12-stator-slot/8-rotor-pole (12/8) IPM machine is discussed, where the expressions of permanent-magnet-excited (PM-excited) and armature fields are derived. Secondly, the total torque ripple is divided into three components, namely, the PM-excited cogging torque, the armature cogging torque, and the modulation torque ripple. Additionally, the relationship between the field harmonics and the torque ripple is discussed based on the GAFMT. Then, a finite element analysis (FEA)-assisted dual fast Fourier transformation (FFT) method is proposed to obtain the accurate value of the field amplitude for torque ripple calculation. The field analysis results based on the GAFMT and the proposed torque ripple are then validated by comparing their results with those obtained from the FEA simulations, and a good agreement is observed, demonstrating the effectiveness of the field analysis and the proposed torque ripple model. Finally, experiments on a prototype 12/8 IPM machine demonstrate the validity of the torque ripple model, providing an effective method for torque ripple suppression of IPM machines.

Experimental Validation of Torque Ripple Reduction in MMC-Fed BLDC Motor Using the Proposed Phase Modulated Model Predictive Control

This paper presents the torque ripple analysis of a brushless DC (BLDC) motor. This torque ripple is generated by generating the ripple in the stator current. For reducing the ripple, a phase-modulated model predictive current control strategy has been implemented in an MMC-fed BLDC motor. The performance of the torque ripple of the BLDC motor is enhanced by using the proposed phase-modulated model predictive control (PMMPC) technique as compared to the model predictive control (MPC) and proportional-integral (PI) controller. Moreover, the performance of the torque ripple is enhanced by increasing the switching frequency for all controllers. A comparative analysis of the torque ripple of the BLDC motor is depicted for different current control and different switching frequency. A harmonic distribution is also shown for all control techniques at switching frequencies of 1, 5, and 10 kHz. The harmonic content is minimum for the PMMPC technique when compared to the other mentioned control technique. The experimental validation of simulation results has also been done here.

Analysis of torque ripple and torsional vibration considering Hall mounting errors in permanent magnet synchronous motors for light EVs

Analysis of torque ripple and torsional vibration considering Hall mounting errors in permanent magnet synchronous motors for light EVs

Torque Ripple Analysis of Double Rotor Eccentric Shell Rotating Multi-Speed Motor with Equal Width Curve

With the rapid development of hydraulic technology, the type and performance of hydraulic motor are put forward higher requirements. In the actual working condition, the motor needs to have more than one stable torque and torque output, but the existing motor cannot be realized. In order to solve this problem, a series of new hydraulic motors based on double rotor structure are developed, thus further developing the multi-speed motor with equal width curve double rotor eccentric shell. One stator and two rotors cooperate with each other and enter through different inputs. The connection of the oil outlet can output a variety of different speed and torque, which realizes the function that multiple motors work synchronously and independently of each other in one shell. This paper mainly introduces the structural characteristics and working principle of the motor, and deduces the instantaneous torque and torque pulsation coefficient of the motor when working alone and in combination. At the same time, in order to understand the torque pulsation law of the internal and external motor more intuitively, the torque of the motor is analyzed and verified by Matlab software. It is concluded that the motor can realize many different speed and torque analysis. At the same time, through the analysis of instantaneous torque and torque pulsation coefficient, it can be concluded that the variation law of instantaneous torque output of internal and external motor combination is the best and the torque fluctuation is the smallest compared with that of internal and external motor alone.

Analytical model of electromagnetic torque of surface PM motors considering current harmonicsin electric vehicles

The modeling of the magnetic field, as well as the amplitude prediction and source analysis of torque ripple, are the theoretical basis to reduce the vibration and noise of electric motors. An analytical model of electromagnetic torque of surface permanent magnet motors considering current harmonics, which is capable of purely analytical calculation and theoretical analysis, is proposed in this paper. The open-circuit magnetic field solution considering the stator slot is performed by using the analytical conformal mapping along the deformed solving path, allowing more accurate prediction of the cogging torque. The armature reaction field is derived under any current condition with current harmonics. So far, the analytical model of electromagnetic torque is established, and the purely analytical calculation of torque value and the theoretical analysis of torque ripple characteristics are implemented in an 8-pole-24-slot surface permanent magnet motor used for the propulsion of light electric vehicles. The generation mechanism of constant torque and torque ripple is clarified both under sinusoidal current and harmonic current. Furthermore, the effect of the stator skew slot on the motor torque is well explained to demonstrate the utility of the proposed model. It is found that the skew slot is almost ineffective in mitigating the torque ripple caused by current harmonics.

Analysis of torque ripples and switching losses of a diode clamped inverter fed permanent magnet synchronous motor drive

Analysis of torque ripples and switching losses of a diode clamped inverter fed permanent magnet synchronous motor drive

Analysis of torque ripples and switching losses of a diode clamped inverter fed permanent magnet synchronous motor drive

The modern-day electric vehicles use brush less DC motors (BLDC) and Permanent Magnet Synchronous Motors (PMSM) as the main driving units. The traction systems also have tried PMSM machine as the driving unit. The variable frequency power source is required to control the speed and torque of the motor to meet the load requirements. The Inverter – power modulator is causing the production of ripples in source current and flux components, hence the torque. This paper presents the effect of inverter on the flux and torque ripples. Also, the simulation results of inverter switching losses are discussed.

Design and Development of High-Performance 3kW Electric Vehicle Grade Switched Reluctance Motor

The growth of Electric Vehicles (EV) moving towards to go green in the world. The high cost of EVs mainly depends on an electric motor. The Switched Reluctance Motor (SRM) speed-torque characteristics are perfectly suited for EV drive. Compared to other poly-phase machines, the SRM has high performance, magnet less, fault-tolerant, and high durability. The design has been carried out on electric vehicle grade modelling with different super core materials. This paper proposes the rating of 3kW, 3500rpm, and 8/6 topology by selecting stator and rotor optimal geometric parameters to design an efficient SRM configuration. The design step analyses the flux distribution uniform materials to analyze the performance of flux density, power, torque density, losses, efficiency, and torque ripple analysis. The finite element analysis is comparatively selected to improve the accuracy of material simulation for EV-SRM using Ansys Maxwell software to optimize the design for weight reduction, changing induction to reduce the acoustic noise.

Comparative Analysis of Torque Ripple for Direct Torque Control based Induction Motor Drive with different strategies

ABSTRACT Direct Torque Control (DTC) method is one of the most outstanding and proficient control techniques of the induction motor. The foremost drawback of DTC induction motor drive is high torque pulsation, variable frequency of inverter switching. The main reason of torque pulsation is torque and flux hysteresis band utilised in DTC. DTC method is utilising hysteresis comparators which produce high torque pulsation and unpredictable switching frequency. In this paper, torque ripple analysis of fuzzy logic controller (FLC) based Direct Torque Control (DTC) of three-phase induction motor drive has been discussed. The space vector pulse width modulation (SVPWM) based DTC technique, which operates with the regular switching frequency, helps to solve the fundamental issues of torque pulsation. In addition to this, literature proposes different solutions like a prediction scheme, fuzzy logic controller technique, global minimum torque ripple strategy, constant frequency torque controller (CFTC) Technique, optimal switching instant scheme, duty cycle control scheme, SVPWM DTC for torque ripple reduction. The fuzzy logic controller capabilities for DTC technique are applied with the induction motor (IM) drive for high-performance applications. The simulation results of Conventional DTC, SVPWM DTC, Carrier SVPWM DTC and FLC-DTC method for the induction motor are illustrated. Fuzzy-based DTC technique compared with CSVPWM DTC method and conventional DTC method are presented. The torque ripple of 7.4% for 5 HP induction motor is achieved by FLC-based DTC method. Hardware results for DTC induction motor drive are also demonstrated and discussed. This paper presents improvement in torque ripple reduction with the help of carrier space vector pulse width modulation (CSVPWM) and FLC-based DTC.

Power electronic converter topologies for switched reluctance motor towards torque ripple analysis

The power converter circuit plays a vital role in electric drives. The converters performance has a significant impact on the drive performance as well as cost. There are different motors applied in electric drives, this study primarily focused on torque ripple analysis of Switched Reluctance Motor (SRM) drive and its converter topologies. The SRM salient poles have the stator outer side and the rotor inner side, which is different from the other polyphase machines. Although there have been a number of converters for SRM drives through the years, each converter has its own set of benefits and drawbacks. The choice of a converter is dictated by the application, this article includes a comparative analysis of SRM converter topologies, two level converters branches and multi-level converters branches were discussed in detail with schematic diagram. Based on the survey it is found that an asymmetrical bridge converter best suits for Electric vehicle application due to its advantage of reducing fault tolerant, fast demagnetization and regenerative braking capability. This paper presents the study of 10 kW SRM Drive controlled by asymmetrical bridge converter, in three different phase modification mode such as 6/4, 8/6 and 10/8 using MATLAB simulation and the torque ripples are analysed for each case.

30° Discontinuous PWM-Based Closed Loop Volts/Hz Control of Induction Motor Drive with Slip Regulation

This paper proposes 30° discontinuous PWM-based closed loop volts/Hz control of induction motor drive with slip regulation. The voltage source inverter is carried out with various pulse width modulation (PWM) schemes such as continuous PWM (CPWM) and discontinuous PWM (DPWM) schemes. The inverter's performance is affected by these PWM schemes. Therefore, this paper investigates the PWM schemes for the inverter. It aims to identify a best PWM scheme based on the total harmonic distortion and torque ripple analysis for constant volts/Hz induction motor drive amongst the various PWM schemes in open loop and closed loop and also proposes a 30° DPWM-based closed-loop control. The performance investigations of various PWM schemes based on inverter-fed induction motor have been evaluated analytically and using MATLAB/Simulink environment. Experimental results have been validated. The combination of 30° DPWM with PI control and slip regulation for induction motor makes the speed control system robust and ideal for low-accuracy applications.

Square-wave drive for synchronous reluctance machine and its torque ripple analysis

Synchronous reluctance machine (SynRM) can be perceived as a special type of permanent magnet synchronous machine (PMSM), and shares similar control method, i.e. the sine-wave current drive with sinusoidal phase currents. In this paper, square-wave drive, which is employed for permanent magnet brushless (BLDC) motors, is employed for the SynRM, in order to economically reduce the cost of rotor position sensor. It is revealed that the torque density and efficiency are slightly sacrificed, whereas torque ripple is deteriorated, proving the SynRM with square-wave drive still promising for the cost-sensitive application if torque ripple is not considered as a critical issue. To further investigate the additional pulsating torque under square-wave drive, mathematical model based on a-b-c phase inductance and d-q axis inductance are established, together with the time-stepping FE calculated currents. It is concluded that the harmonics in the currents tend to cause non-sinusoidal variation of the magnetic reluctance, which can be represented as additional inductance harmonics. The harmonics of the current and inductance interact with each other, thus undesirable torque ripple components are produced.

Measurement and Analysis of Torque Ripple in Inverter Driven Electric Machines

Torque ripple in electric machines can create both noise and vibration. While torque ripple is often well understood theoretically, it is much more difficult to accurately predict and measure. Often torque ripple is measured as a function of magnets and slot interaction at extremely low speed, but this can only be extrapolated to understand its implications for noise and vibration and is not useful for understanding torque response during dynamic scenarios like a change in load. The slow speed method of measurement also neglects possible switching effects on the torque profile. This paper will explore challenges in measuring the different sources of torque ripple and give an alternative method to measure torque ripple at higher speeds and also dynamically. This will include best practices and examples.

Performance Analysis and Reduction of Torque Ripple of Axial Flux Permanent Magnet Synchronous Motor Manufactured for Electric Vehicles

Axial flux permanent magnet synchronous motors (AFPMSMs) have advantages over other motor types in terms of efficiency, vibration, and noise. However, torque ripple is an important problem for axial flux permanent magnet (AFPM) motors. One of the methods recommended as a solution to this problem is the skew operation. The skew can be applied to the magnets or the stator. However, for these motors, this process is mostly applied to magnets because the skew applied to the stator makes it difficult to manufacture. In this article, a solution to the torque ripple of an in-wheel AFPMSM for the electric vehicle is sought. For this purpose, designs, optimization, and 3-D analyzes have been carried out. This solution has been applied to magnets designed by skewing for ease of production. 3-D analyses have been carried out by applying skew of up to 40° with an angle of 5° to the magnets in the rotor. In light of the analysis, the most appropriate skew angle that does not affect motor performance has been determined. As a result of the analysis of the motor model obtained with the determined skew angle, it is observed that the torque ripple decreased by 86.71%. Finally, production has been carried out according to the analysis results obtained.