Torque Ripple Of Motor Research Articles

FEM‐coupled simulations and genetic algorithm model applied to reduce the torque ripple of a 2‐phase SR motor drive

In order to reduce the torque ripple of SR motor drive, this work proposes a new methodology based on the converter, controller, and motor modelling, associated with a genetic algorithm optimisation model which uses the electromagnetic vibration data to calculate the best firing angles for the inverter power switches. To implement the power electronic motor drive model and the optimisation procedure, it was used, respectively, with coupled FEM simulations resources and a MATLAB Script. In this work, they were tested with two inverter commutation strategies whose values were validated through the comparison with the experimental results. The simulated and experimental values converge in the same direction, validating the proposed methodology.

PMSM Control using the 3DSVPWM to Decrease Motor Torque Ripple and Motor Current THD with a New Model

In this paper, a new model for a PMSM (permanent magnet synchronous motor) driver is proposed. The proposed model is envisioned as a better modulating drive current waveform. In the proposed system the modulating drive motor current waveform is more similar to ideal sinusoidal waveform. Advanced IGBTs and snubber circuits can be employed in the design of the driver to obtain high performance with a simultaneous reduction in THD (total harmonic distortion) and torque ripple of the motor. The proposed concept offers a significant decreasing for driver harmonics compared to classical SVPWM used. The inverter can be operated in 3-phase and 20 kHz switching frequency. A PMSM motor is operated at 3kW and 48V with the proposed model is evaluated via simulation with a corresponding SVPWM (space vector pulse width modulation) method. Results of torque ripple and THD of the motor currents on the model are discussed.

Novel Rotor Design of Wound Field Synchronous Motor for Torque Ripple Reduction in ISG System

This paper describes a method to reduce the torque ripple for the Wound Field Synchronous Motor, which does not use a permanent magnet. When a WFSM is used in an Integrated Starter Generator system, it must have a higher power density than other automotive motors in order to satisfy the size constraints and required power. An increase in the power density creates a magnetic flux saturation in the rotor, and this soon becomes the cause of an increase in the torque ripple of motor. An increase in the torque ripple can degrade the Noise Vibration Harshness characteristics of automotive by creating vibration and noise in the engine start-up mode, in which the maximum torque is generated in an ISG system. This paper proposes a method of reducing the torque ripple via a design that uses a flux barrier model in the WFSM’s rotor. The Response Surface Method is used to optimize the flux barrier model, and Finite Element Method is used to to verify the torque ripple reduction.

Research on the Influences of Time Harmonics on Permanent Magnet Synchronous Motors with Hybrid Magnet Poles

With the development of electric electron technology and controlling technology, controller for driving permanent magnet synchronous motors is used widely. The using of a controller can expand the motor speed range and improve motor runtime performances. However, the output current of a controller contains lots of time harmonics that will have bad influences on motor torque and losses. In order to analyze the influences of the time harmonics on the motor performances, different time harmonic currents were injected into the motor armature. Taking a 750 W, 250 r/min permanent magnet synchronous motor with hybrid magnet poles (HPPMSM) as an example, the 2-D finite model was established. On this basis, the torque ripple and eddy current losses of permanent magnets with different time harmonics were obtained. The influences of time harmonics on motor torque ripple and eddy current losses were determined, and the impacting mechanism was revealed. The analyses may be helpful for the optimal design of HPPMSM.

Drive circuit‐based torque‐ripple suppression method for single‐phase BLDC fan motors to reduce acoustic noise

This paper proposes a drive circuit for single-phase brushless direct current (BLDC) fan motors to reduce their acoustic noise. First, the torque ripple of a single-phase BLDC motor is analysed theoretically. Then, a drive circuit that is capable of regulating the DC-link voltage during commutation to weaken the negative effect of current lag is proposed to reduce the acoustic noise of single-phase BLDC fan motors. Furthermore, the characteristics of the proposed drive circuit are discussed theoretically using a deduced analytical model of the proposed drive circuit. Additionally, simulations based on the finite element method and experiments are performed. The torque ripple and acoustic noise generated by the conventional and proposed drive circuits are compared. The simulation results show that the torque ripple is reduced by 16.1% when the proposed drive circuit is used, and the experimental results illustrate that the acoustic noise generated by the second harmonic of the torque ripple is reduced by 7.3%. Ultimately, the effectiveness of the proposed drive circuit is verified.

Research on PMSM harmonic coupling models based on magnetic co‐energy

Modelling of the permanent magnet synchronous motor (PMSM) torque ripple and PMSM current harmonics controlling technology are important branches of PMSM research. Based on the existing linear PMSM model derived from magnetic co-energy, this study considers the variation of PMSM parameters (inductance, permanent magnet flux and cogging torque) caused by magnetic saturation. Then, the harmonic coupling models including flux-current coupling model, voltage-current coupling model and torque-current coupling model are deduced. In these harmonic coupling models, the PMSM parameters no longer vary with rotor position but only with current amplitude and phase. Based on the torque-current coupling model, a novel method of obtaining the required injecting currents which could suppress torque ripple is proposed. The validity of the harmonic coupling models and the injecting current solution method is verified by finite-element method.

Analysis and Design of a Speed Controller for Switched Reluctance Motor Drive

This paper presents a high precision speed control of the reluctance machine for electric drive applications. To get high resolution speed control, it is developed a cascade control algorithm based on linear control technique. The controller was designed using the Root Locus Methodology and has been implemented on a numerical simulation platform. It is shown that Root Locus Methodology design is a viable approach, and that various problems associated with the structural torque ripple of the electric motor can be solved. An important aspect of this work is the role played by model linearization in testing the sensitivity of the controller performance to specific parameter changes. The controller was implemented in a simulated non-linear switched reluctance motor model in order to evaluate their performances. Simulations results show that the high-performance control for Switched Reluctance Motor has been achieved.

Simultaneous suppression of torque ripple and flexible load vibration for PMSM under stator current vector orientation

Torque ripple of permanent magnet synchronous motor (PMSM) will result in the distortion of current waveform and the load flexibility of spiral torsion spring (STS) will affect the control performance of driving system. This study focuses on a new control problem of simultaneous suppression of PMSM's torque ripple and flexible load's vibration. First, the Lagrange equation is used to establish the dynamic model of STS to describe its vibration mode. The overall model of STS directly derived by PMSM under stator current vector orientation is built. Then, based on the magnetic co-energy model of electromagnetic torque of PMSM, the constraint relation of optimal stator harmonic current under the condition of torque ripple minimisation is derived, and the controller based on stator current oriented closed-loop I/f control to suppress load vibration and torque ripple simultaneously is presented through backstepping control. A wide speed range identification method based on the least-square algorithm with a forgetting factor is also designed. The simulation and experiment show that the speed identification algorithm can estimate the speed accurately in a wide range. The proposed control scenario improves control performance, smoothes current waveform and inhibits torque ripple and load vibration effectively.

Dual-Vector Predictive Torque Control of Permanent Magnet Synchronous Motors Based on a Candidate Vector Table

In order to reduce the torque ripple of permanent magnet synchronous motors (PMSMs), this paper proposes a dual-vector predictive torque control strategy based on a candidate vector table. The main feature of this strategy is that two vectors are acted in a control period to form a vector combination, and the vector combination can be either an effective-zero combination or an effective-effective combination. In the process of establishing the vector combinations, the switching frequency is also taken into account, therefore avoiding a high switching frequency, while effectively reducing the motor torque ripple. The candidate vector table is constructed offline, and three sets of candidate vectors and their duty cycles can be determined by looking up the table. Then the cost function is used to screen the action vectors from the three sets candidate vectors, so the two vectors acted in one control period and their duty cycles can be obtained simultaneously. Finally, the feasibility and effectiveness of the proposed method are verified on a 5.2 kW two-level inverter-fed PMSM drive system.

Advanced Drive System for DC Motor Using Multilevel DC/DC Buck Converter Circuit

This paper presents a new topology of clamped diode multilevel DC/DC buck power converter for a DC motor system. The proposed converter circuit consists of four cascaded MOSFET power switches with three clamping diodes and four voltage sources (voltage cells) connected in series. The main objective of the new topology is to reduce current ripples and torque ripples that are associated with hard switching of the traditional chopper circuit. When the voltage profile of this converter is applied on a DC motor, it positively affects the performance of the DC motor armature current and the generated dynamic torque. The output voltage of the proposed topology shows an adequate performance for tracking of reference voltage with small ripples that are normally reflected into smaller EMI noise. Moreover, it has been shown that the operation of the DC motor with the newly proposed chopper topology greatly decreases the motor armature current ripples and torque ripples by a factor equal to the number of the connected voltage cells. Both simulation and experimental results on a prototype of a DC motor are provided to validate the proposed chopper topology. The results prove that the mechanical vibration and acoustic noises have also been reduced roughly by 13 dBs with a continuous variable input voltage pattern.

Speed Control of Load Torque Feedforward Compensation Based on Linear Active Disturbance Rejection for Five-Phase PMSM

This study focuses on the speed control problem of a five-phase permanent magnet synchronous motor (PMSM) in the presence of a variable load torque and unknown model parameters. To overcome the mutual transmission of motor torque ripple and load disturbance when the five-phase PMSM directly drives the load, a control method of load torque feedforward compensation based on linear auto disturbance rejection controller (LADRC) is proposed. First, the load torque observer is introduced to observe the load torque which is used as feedforward compensation to eliminate the effects of load torque changes. Second, an LADRC in the outer speed loop is presented to estimate the disturbance, and the stability of LADRC is analyzed. Third, the proposed torque feedforward method based on the LADRC is compared with the traditional proportional integral (PI) torque feedforward method. The PI regulators for current loops are designed. Finally, the simulation models are built and the control algorithms are both implemented using a TMS320F28335 DSP. The simulation and experiment results show that the proposed load torque feedforward compensation based on the LADRC produces excellent dynamic performance, such as smaller overshoot and faster response time. The proposed control scheme is robust and has a strong anti-disturbance ability, even in the case of large load torque disturbances.

Longitudinal vibration analysis and suppression of electric wheel system driven by in-wheel motor considering unbalanced magnetic pull

With the blowout of electric vehicles recently, the key parts of the electric vehicles driven by in-wheel motors named the electric wheel system become the core of development research. The torque ripple of the in-wheel motor mainly results in the longitudinal dynamics of the electric wheel system. The excitation sources are first analyzed through the finite element method, including the torque ripple induced by the in-wheel motor and the unbalanced magnetic pull produced by the relative motion between the stator and rotor. The accuracy of the finite element model is verified by the back electromotive force test of the in-wheel motor. Second, the longitudinal-torsional coupled dynamic model is established. The proposed model can take into account the unbalanced magnetic pull. Based on the model, the modal characteristics and the longitudinal dynamics of the electric wheel system are analyzed. The coupled dynamic model is verified by the vibration test of the electric wheel system. Two indexes, namely, the root mean square of longitudinal vibration of the stator and the signal-to-noise ratio of the tire slip rate, are proposed to evaluate the electric wheel longitudinal performance. The influence of unbalanced magnetic pull on the evaluation indexes of the longitudinal dynamics is analyzed. Finally, the influence of motor’s structural parameters on the average torque, torque ripple, and equivalent electromagnetic stiffness are analyzed through the orthogonal test. A surrogate model between the structural parameters of the in-wheel motor and the average torque, torque ripple, and equivalent electromagnetic stiffness is established based on the Bp neural network. The torque ripple and the equivalent electromagnetic stiffness are then reduced through optimizing the structural parameters of the in-wheel motor. It turns out that the proposed Bp neural network–based method is effective to suppress the longitudinal vibration of the electric wheel system.

Compensation for Inverter Nonlinearity in Permanent Magnet Synchronous Motor Drive and Effect on Torsional Vibration of Electric Vehicle Driveline

Permanent magnet synchronous motors (PMSMs) with inverters are widely used in electric vehicles (EVs). However, current harmonics caused by the nonlinearity of the inverter generate torque ripples and give rise to torsional vibration in the vehicle driveline. This paper proposes a new compensation method to suppress the torque ripples. This method extracts the 6th-order harmonic component online from the d-axis and q-axis currents with the approximate Fourier transform, and adopts a harmonic current PI regulator to calculate compensation voltage, which is added to the voltage reference to compensate the nonlinearity of the inverter. After correcting the current distortion and improving the motor torque smoothness, the torsional vibration of the driveline caused by the motor pulsating torque is reduced. According to the simulation results, the 6th-order of motor torque ripple and the torsional vibration response is reduced about 26–28%, which confirms the validity of the proposed strategy. The proposed method does not need any additional hardware and can be implemented broadly in PMSM drives.

Improved Finite Control-Set Model-Based Direct Power Control of BLDC Motor With Reduced Torque Ripple

This paper deals with active torque ripple compensation based on direct power control of permanent magnet brushless DC (BLDC) motor drive. The torque undulations caused by the mismatch between stator current and its nonsinusoidal back electromotive force (back EMF) waveforms is a well-known issue on BLDC motor drives. In this paper, to remedy this problem, a simple and comprehensive direct power control based approach is proposed. Instead of using conventional field-oriented control or direct torque control schemes, which are widely used in ac machines with sinusoidal flux distribution, an alternative approach is presented to control the mutual torque production through an active and reactive rotor power control loop. As a result, the proposed approach provides a simple way to reduce torque ripple of a permanent magnet synchronous motor with nonsinusoidal back EMF without requiring rotor orientation or back EMF harmonic content estimation method. In order to synthesize the proper input voltages in the context of torque ripple minimization, high bandwidth controllers are required to cope the torque ripple frequencies. In this sense, the power control loop is implemented based on two-vector finite control-set model-based predictive control approach, which provides fast torque response and good steady-state performance. The validity of the proposed control scheme for low torque ripple BLDC motor drive is verified through experimental results, achieving good steady-state performance while maintaining quick dynamic response.

Analysis and Design of a Compound-Structure Permanent-Magnet Motor for Hybrid Electric Vehicles

On the basis of the excellent driving force demand of hybrid electric vehicles (HEVs), this paper studies the torque property of the compound-structure permanent-magnet motor (CSPM motor) used for HEVs, which is influenced by magnetic field oversaturation and variable nonlinear parameters. Firstly, the system configuration of HEVs based on CSPM motor and its working mode are introduced. Next, the state equation of CSPM motor in three-phase stationary coordinate system is proposed in order to investigate its torque performance; then, the factors affecting the output torque are gained. Finite element method (FEM)-based electromagnetic parameters analysis and design is carried out, to raise the output torque and reduce the torque ripple of CSPM motor. Besides, optimized design parameters are used to establish the FEM model, and the simulation results of electromagnetic performances for the CSPM motor before and after optimization are given to verify the rationality of optimization.

Hybrid control technique for minimizing the torque ripple of brushless direct current motor

This paper presented the brushless direct current motor torque ripple reduction based on the speed and torque control using hybrid technique. The dynamic behavior of the brushless direct current motor is analyzed in terms of the parameters such as the speed, current, back electromotive force and torque. Based on the parameters, the motor speed is controlled and minimized the torque ripples. For controlling the speed of the brushless direct current motor is utilized the fractional-order proportional–integral–derivative controller for generating the optimal control pulses. With the use of fractional-order proportional–integral–derivative controller, the optimal gain parameters are needed to reduce the torque ripples and control the speed of brushless direct current motor. By utilizing the hybrid technique, the gain parameters are utilized to analyze the optimal gain parameters of fractional-order proportional–integral–derivative controller. The hybrid technique is the combination of adaptive neuro-fuzzy inference system with firefly algorithm. The proposed strategy is simple in structure and robust to reduce the complexities of the mathematical computations. Initially, the nature inspired optimization algorithm of firefly algorithm is analyzed for finding the error function. In addition, the efficient adaptive neuro-fuzzy inference system controller which becomes an integrated method of approach is performed to control the error functions in order to yields excellent optimized gain values. After that, the control signals are applied to the input of voltage source converter of brushless direct current motor. With this control strategy, the harmonics and torque ripples are minimized. Based on the proposed control strategy, the speed and torque performance is analyzed. The effectiveness of the proposed technique is implemented in MATLAB/Simulink platform and evaluates their performance. The performance analysis of the proposed method is demonstrated and contrasted with the existing techniques such as bat algorithm, particle swarm optimization algorithm and ant–lion optimizer algorithm with fractional-order proportional–integral–derivative controller techniques.

A novel scheme for torque ripple minimization of BLDC motor used in solar air conditioner

The application of BLDC motor is constrained to certain areas due to its drawback of torque ripple. This paper presents a novel scheme of reducing the commutation torque ripple of BLDC motors by injecting additional voltage in the non-commutating phase of the motor. In this work, two independent output voltages with different magnitudes are provided by single-input dual-output (SIDO) converter. One of the voltages (Vdc1) is connected to voltage source inverter which runs BLDC motor. Another voltage (Vdc2) is added to the main voltage (Vdc1) as an additional voltage at the time of commutation between any two phases. The SIDO converter is fed from PV system incorporated with MPPT scheme. The proposed configuration is developed and simulated in MATLAB/Simulink. Results prove the effective utilization of solar power for running the BLDC motor with reduced torque ripple and applicability of the proposed scheme in solar-powered air conditioner.

Optimization of PWM for the Overmodulation Region of Two-Level Inverters

Three optimized pulse-width modulated (PWM) techniques for the overmodulation region of two-level inverter-fed ac drives are introduced and investigated from the harmonic loss minimization point of view. The optimization is elaborated for the lowest loss-factor, which is proportional to the square of the root mean square value of current harmonics. The loss-factors are computed for different switching numbers as the function of the motor fundamental voltage. It is shown that, with respect to the motor heating and torque ripples, the acceptable drive condition can be guaranteed by a relatively low value of an inverter switching frequency up to 96%-97% of maximal possible motor voltage. Furthermore, it is shown that the so-called three-vector methods have considerably better performance in the lower part of the overmodulation region than the so-called two-vector method for the same number of switching. The performance of the techniques is compared with other existing PWM techniques. This paper discusses the implementation details of the proposed optimal PWM techniques. The theoretical results are verified by experimental and simulation tests.

An Efficient DSP–FPGA-Based Implementation of Hybrid PWM for Electric Rail Traction Induction Motor Control

Low switching frequency is always used in an electric rail traction induction motor control system, in order to reduce switching losses and increase system reliability. But under low switching frequency, the conventional single pulse width modulation (PWM) technique for the whole speed region will produce a large number of harmonic components, which in turn cause motor heating, torque ripple, and other adverse effects. In this paper, a hybrid PWM technique formed by merging carrier-based asynchronous and synchronous modulation and optimal synchronous modulation is proposed to achieve low losses and total harmonics based on very low switching frequency. A simple low-cost and low-power digital signal processor (DSP) and field programmable gate array (FPGA) hybrid hardware structure is then adopted for implementing the technique, which fully utilizes advantages and resources of each processor. Total harmonic distortion of the system can hence be reduced by operating with the high-precision hybrid PWM, while not compromising the multirate and multitask processing requirements of traction control. Detailed implementations in both DSP and FPGA with high accuracy, low usage of resources, and computational burden are then described, focusing particularly at the smooth transitions among different PWM schemes. Simulations and experiments are eventually performed with results captured for validating the presented hybrid PWM technique.

Modified Rotor Material for Minimization of Torque Ripple for Interior Permanent Magnet BLDC motor

This paper presents a method to minimize the torque ripple of an interior permanent magnet BLDC motor by adopting modified rotor. The analysis method for torque ripple are established using two- dimensional (2 –D) finite-element method (FEM). A cost-effective modified rotor technique is proposed to minimize the torque ripple of the BLDC motor. This proposed method for low torque ripple has an advantage over rotor step skewing method from a manufacturing point of view. The proposed model is compared with the modified rotor method and non-modified rotor method by calculating torque characteristics to determine the effective method to minimize torque ripple distortion. Finally, the finite-element method results have revealed that the rotor angle vs torque. It shows the lower torque ripple but show a maximization of the average torque.