Minimization of Torque-Ripple in Switched Reluctance Motors Over Wide Speed Range

Milad Dowlatshahi,Seyed Morteza Saghaiannejad,Jin-Woo Ahn,Mehdi Moallem 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.2

Torque pulsation mechanism and highly nonlinear magnetic characterization of switched reluctance motors(SRM) lead to unfavorable torque ripple and limit the variety of applications in industry. In this paper, a modification method proposed for torque ripple minimization of SRM based on conventional torque sharing functions(TSF) to improve maximum speed of torque ripple-free operation considering converter limitations. Due to increasing phase inductance in outgoing phase during the commutation region, reference current tracking can be deteriorated especially when the speed increased. Moreover, phase torque production in incoming phase may not be reached to the reference value near the turn-on angle in which the incremental inductance would be dramatically decreased. Torque error for outgoing phase can cause increasing the resultant motor torque while it would be negative for incoming phase and yields reducing the motor torque. In this paper, a modification method is proposed in which phase torque tracking error for each phase under the commutation added to the other phase so that the resultant torque remained in constant level. This yields to extend constant torque region and reduce peak phase current when the speed increased. Simulation and experimental results for four phase 4 KW, 8/6 SRM validate the effectiveness of the proposed scheme.

Torque Ripple Reduction Using Torque Compensation Effect of an Asymmetric Rotor Design in IPM Motor

Yong-Suk Hwang,Myung-Hwan Yoon,Jin-Cheol Park,Jung-Pyo Hong 한국자기학회 2017 Journal of Magnetics Vol.22 No.2

In this paper, torques of two motors are compared by Finite Element Analysis (FEA). One has a symmetric rotor structure and the other has an asymmetric rotor structure. The comparison shows that the asymmetric rotor structured motor has reduced torque ripple compared to the symmetric. The torque of the compared motor models was analyzed by separating into magnetic torque and reluctance torque. Through the analysis of torque component separated, it is shown that the magnetic torque and the reluctance torque compensate each other in the motor with the asymmetric structure rotor. Here “compensate” means decrementing the effect of one or more harmonics. It is shown how this compensation appears between the magnetic torque and the reluctance torque by looking into back electro motive force (emf) and the relative permeability distribution of rotor core.

Torque-Angle-Based Direct Torque Control for Interior Permanent-Magnet Synchronous Motor Drivers in Electric Vehicles

Xin Qiu,Wenxin Huang,Feifei Bu 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.6

A modified direct torque control (DTC) method based on torque angle is proposed for interior permanent-magnet synchronous motor (IPMSM) drivers used in electric vehicles (EVs). Given the close relationship between torque and torque angle, proper voltage vectors are selected by the proposed DTC method to change the torque angle rapidly and regulate the torque quickly. The amplitude and angle of the voltage vectors are determined by the torque loop and stator flux-linkage loop, respectively, with the help of the position of the stator flux linkage. Furthermore, to satisfy the torque performance request of EVs, the nonlinear dead-time of the invertor caused by parasitic capacitances is considered and compensated to improve steady torque performance. The stable operation region of the IPMSM DTC driver for voltage and current limits is investigated for reliability. The experimental results prove that the proposed DTC has good torque performance with a brief control structure.

Torque-Angle-Based Direct Torque Control for Interior Permanent-Magnet Synchronous Motor Drivers in Electric Vehicles

Qiu, Xin,Huang, Wenxin,Bu, Feifei The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.6

A modified direct torque control (DTC) method based on torque angle is proposed for interior permanent-magnet synchronous motor (IPMSM) drivers used in electric vehicles (EVs). Given the close relationship between torque and torque angle, proper voltage vectors are selected by the proposed DTC method to change the torque angle rapidly and regulate the torque quickly. The amplitude and angle of the voltage vectors are determined by the torque loop and stator flux-linkage loop, respectively, with the help of the position of the stator flux linkage. Furthermore, to satisfy the torque performance request of EVs, the nonlinear dead-time of the invertor caused by parasitic capacitances is considered and compensated to improve steady torque performance. The stable operation region of the IPMSM DTC driver for voltage and current limits is investigated for reliability. The experimental results prove that the proposed DTC has good torque performance with a brief control structure.

Torque Ripple Minimization in Direct Torque Control of Brushless DC Motor

Zhenguo Li,Songfa Zhang,Shenghai Zhou,Jin-Woo Ahn 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.5

This paper mainly proposes a direct torque control strategy to minimize torque ripple in brushless DC (BLDC) motor. BLDC motor has large current and torque ripple when one voltage vector applied in one cycle due to its low inductance. Hence, this paper proposed a hysteresis torque control with PWM mode to control the resultant torque. Moreover, when the direct torque control system is operating during the two-phase half-bridge 120° conduction mode, large torque ripple in commutation area appears every 120 electrical degree. Based on analyzing the root of torque ripple in detail, lookup tables of switching devices states for new half-bridge modulation mode in the positive and negative reference torque put forwarded. Finally, simulations by MATLAB software and experiment results from DSP are presented to verify the feasibility and effectiveness of the proposed strategy operating in four-quadrant operation.

Minimization of Torque-Ripple in Switched Reluctance Motors Over Wide Speed Range

Dowlatshahi, Milad,Saghaiannejad, Seyed Morteza,Ahn, Jin-Woo,Moallem, Mehdi The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.2

Torque pulsation mechanism and highly nonlinear magnetic characterization of switched reluctance motors(SRM) lead to unfavorable torque ripple and limit the variety of applications in industry. In this paper, a modification method proposed for torque ripple minimization of SRM based on conventional torque sharing functions(TSF) to improve maximum speed of torque ripple-free operation considering converter limitations. Due to increasing phase inductance in outgoing phase during the commutation region, reference current tracking can be deteriorated especially when the speed increased. Moreover, phase torque production in incoming phase may not be reached to the reference value near the turn-on angle in which the incremental inductance would be dramatically decreased. Torque error for outgoing phase can cause increasing the resultant motor torque while it would be negative for incoming phase and yields reducing the motor torque. In this paper, a modification method is proposed in which phase torque tracking error for each phase under the commutation added to the other phase so that the resultant torque remained in constant level. This yields to extend constant torque region and reduce peak phase current when the speed increased. Simulation and experimental results for four phase 4 KW, 8/6 SRM validate the effectiveness of the proposed scheme.

ENGINE NET TORQUE COMPENSATION THROUGH DRIVELINE TORQUE ESTIMATION IN A PARALLEL HYBRID VEHICLE

Jinrak Park,Seibum Choi,Jiwon Oh,Jeongsoo Eo 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.3

In recent years, interest in smart and green vehicles has increased. There are many cases where engine net torque related control is performed when building smart and green car systems. Speed tracking control in autonomous driving, or optimal transmission shift control is an example. The engine net torque is the sum of the engine indicated torque, accessory load torque, and frictional torque, and the starter motor torque in the case of a parallel hybrid vehicle. However, the estimation error of these torque items can cause the estimation error of the engine net torque. In this paper, a compensation method for the slowly varying uncertainty of the engine net torque in a parallel hybrid vehicle using a multiplicative constant is proposed. The adaptation of the multiplicative constant is conducted using the amount of change in the engine net torque estimated in the backward direction of the driveline. The proposed algorithm is verified based on production vehicle data.

회전방지장치와 지대주의 내육각구조가 임플란트로 전달되는 조임 회전력에 미치는 영향

이상민,전영찬,정창모,Lee Sang-Min,Jeon Young-Chan,Jeong Chang-Mo 대한치과보철학회 2003 대한치과보철학회지 Vol.41 No.2

Statement of problem : Little is known about the effect of a counter-torque device and the internal hexagon of abutment on the tightening torque transmitted to the implant. Purpose : The purpose of this study was to examine the effect of a counter-torque device and the internal hexagon of abutment on the tightening torque transmitted to the implant. Material and Methods : In this study, three types of abutment were used, (1) two-piece conical abutment with hexagon, (2) two-piece conical abutment without hexagon, and (3) one-piece conical abutment without hexagon. The experimental groups were divided into five groups according to the type of abutment and the usage of a counter-torque device. Group I : two-piece conical abutment with internal hexagon was tightened without the use of a counter-torque device. Group II : two-piece conical abutment without internal hexagon was tightened without the use of a counter-torque device. Group III : one-piece conical abutment without internal hexagon was tightened without the use of a counter-torque device. Group IV : two-piece conical abutment with internal hexagon was tightened with the use of a counter-torque device Group V : two-piece conical abutment without internal hexagon was tightened with the use of a counter-torque device. Abutments were tightened 20Ncm torque with the use of manual torque wrench and then torque values were measured by torque-gauge. After the measurement of torque values, all groups were loosened with the use of manual torque wrench and then detorque values were measured by torque-gauge. Results : The results were as follows. 1. There were no differences in torque values among three types of abutment. 2. Regardless of the existence of the internal hexagon of abutment, a counter-torque device decreased the tightening torque transmitted to the implant about 92% 3. In group III showed the highest detorque value, however there were no differences among group I, II, IV and V. Conclusion : Within the limitations of this study, it was concluded that the internal hexagon of abutment has no effect on the tightening torque transmitted to the implant and the detorque value of abutment screw. The use of a counter-torque device is essential to prevent microfracture on the implant-bone interface but has no effect on preload.

Comparison of the torque stability of Implant Torque Controllers

Kim, Dae-Gon,Cho, Lee-Ra,Park, Chan-Jin Korean Academy of Dental Science 2009 Journal of korean dental science Vol.2 No.1

Tightening of the screws in implant restorations should be accurate and precise. If applied torque is too low, screw loosening would be occurred. With too high torque, the screw fracture might take place. Various torque generating devices are developed and employed to apply a proper torque. The purpose of this investigation was to determine and compare the accuracy of the torque controllers. In this study, 4 types of torque controllers were used; electronic torque controller, torque limiting device, torque indicating device and contra angle torque driver. Digital torque gauge was employed to measure the de-torque value. Thirty cycles of tightening and loosening were done with each torque controller. All implant torque controllers have shown slight errors and deviations. The torque liming device exhibited the most accurate data. No significant difference was found among the mean de-torque values of the electronic torque controller, torque indicating device and contra angle torque driver. In the limitation of this study, it would be recommended that the implant torque controllers should be checked whether uniformed and precise torque can be generated and a measuring error should be corrected.

Analysis of Cogging Torque Reduction of IPMSM applying Skew Method

In-Soo Song,Do-Hyun Kim,Ki-Chan Kim ASCONS 2020 IJASC Vol.2 No.3

Background/Objectives: In a rotating machine such as Interior Permanent Magnet Synchronous Motor (IPMSM), which is widely used in industrial fields. The reluctance torque is generated by the difference when magnetic energy varies according to the relative position of the pole and slot in a slot shaped motor. The reluctance torque acts as a torque ripple in electrical equipment and causes noise and vibration. It generated by the influence of the slot in the permanent magnet device is called cogging torque, and a skew was applied as a method to reduce the cogging torque to analyze the characteristics of the motor. In this paper, we analyze the back electromotive force and torque characteristics of IPMSM motors applying 3-stage skew among various cogging torque reduction methods, and reduce torque ripple in the instantaneous and continuous sections of the motor through Finite Element Method (FEM). Findings: Therefore, in this paper, we discuss how to apply skew among many analysis methods for reducing cogging torque. It shows the procedure for reducing cogging torque by applying skew from the comparative model. Finally, it analyzes the characteristics of the existing model and the model to which the skew is applied, and indicates how much it has increased. Improvements/Applications: By applying a three-stage skew to the model applied in this paper, the effect of noise and vibration can be reduced through cogging torque reduction.