Jianxin Shen and Dong-Min Miao
The purpose of this paper is to focus on the machine design and control strategy of the permanent magnet synchronous generator (PMSG) system, especially utilized in variable speed…
Abstract
Purpose
The purpose of this paper is to focus on the machine design and control strategy of the permanent magnet synchronous generator (PMSG) system, especially utilized in variable speed applications, in order to stabilize the output voltage on the dc link over a wide speed range.
Design/methodology/approach
Different ac/dc power converter topologies are comparatively studied, each with an accordingly designed PMSG, so as to investigate the influence of the armature winding inductance as well as the relationship between the PMSG and power converter topologies.
Findings
Pulse width modulation (PWM) rectifier is preferable for the said application due to its good performance and controllability. Moreover, by employing the PWM rectifier, relatively large inductance of the PMSG is considered for both short-circuit current reduction and field regulation.
Originality/value
Field-regulating control is realized with a space vector PWM (SVPWM) rectifier, which can weaken the PMSG magnetic field during high-speed operation, while even properly enhance the field at low speed, ensuring a small change of the PMSG output voltage and a stable dc voltage.
Details
Keywords
Jianxin Shen, Kang Wang, Dan Shi, Canfei Wang and Mengjia Jin
The purpose of this paper is to present the optimal design of a low-cost interior permanent magnet (IPM) alternating current (AC) motor. It examines the influence of the permanent…
Abstract
Purpose
The purpose of this paper is to present the optimal design of a low-cost interior permanent magnet (IPM) alternating current (AC) motor. It examines the influence of the permanent magnet (PM) materials, and proposes a simple and practical method of optimizing the air-gap field to achieve sinusoidal back electromotive force (EMF), and to reduce the cogging torque.
Design/methodology/approach
IPM AC motors with different magnet materials and various topologies are comparatively studied. Finite element method (FEM) is used to predict the performances of these designs. Material costs and manufacture costs are both taken into account. Finally, an optimized design is prototyped and tested, validating the design considerations.
Findings
In an IPM AC motor, even if the rotor outer profile is round, the air-gap field distribution can be fined, while the cogging torque can be significantly reduced, by properly shaping the stator tooth tips. Nevertheless, this technique is usually applicable to motor configurations with concentrated windings, but not to those with distributed windings.
Originality/value
While using ferrite magnets for PM AC motors with a kW power, interior magnets are usually inserted in V-shaped slots, and the rotor outer profile is often shaped in order to enhance the air-gap field distribution. However, such a rotor configuration usually increases the manufacture costs, and also deteriorates the consistency of mass production. Therefore, a new motor configuration with a round rotor outer profile and shaped stator tooth tips is proposed. It can not only overcome the aforementioned problems, but also improve the motor performance.
Details
Keywords
Jianxin Shen, Dan Shi, Canfei Wang, Peng Li, Kang Wang and Mengjia Jin
The purpose of this paper is to investigate a new cause of torque ripple in interior permanent magnet (IPM) alternating current (AC) motors, which is common but has hardly been…
Abstract
Purpose
The purpose of this paper is to investigate a new cause of torque ripple in interior permanent magnet (IPM) alternating current (AC) motors, which is common but has hardly been studied. The paper also proposes a new method to suppress the total torque ripple.
Design/methodology/approach
Besides the well-known cogging torque and mutual torque ripple, a new ripple which exists in the reluctance torque is found. It is verified with both analytical model and finite element analysis. Also, a novel method is proposed to reduce the reluctance torque ripple, with experimental validation.
Findings
It is usually said that the winding inductances of an IPM AC motor vary sinusoidally with the rotor position, thus, the d-axis and q-axis inductances are constant, whilst the reluctance torque is smooth. However, in most practical motors, the inductances vary irregularly, causing a significant ripple in the reluctance torque. Moreover, in machine design, it is always desirable to suppress the cogging torque as much as possible. However, in this paper, it is proved that the cogging torque can remain and be used to cancel the reluctance torque ripple.
Originality/value
Torque ripple in the IPM AC motors is usually reduced by suppressing the cogging torque and making both back electromotive forces and currents sinusoidal. However, this paper reveals the new cause of the torque ripple due to the irregular variation of winding inductances. Moreover, the paper gives a new method to cancel the reluctance torque ripple with the cogging torque.
Details
Keywords
Yajun Yin, Wei Duan, Kai Wu, Yangdong Li, Jianxin Zhou, Xu Shen and Min Wang
The purpose of this study is to simulate the temperature distribution during an electron beam freeform fabrication (EBF3) process based on a fully threaded tree (FTT) technique in…
Abstract
Purpose
The purpose of this study is to simulate the temperature distribution during an electron beam freeform fabrication (EBF3) process based on a fully threaded tree (FTT) technique in various scales and to analyze the temperature variation with time in different regions of the part.
Design/methodology/approach
This study presented a revised model for the temperature simulation in the EBF3 process. The FTT technique was then adopted as an adaptive grid strategy in the simulation. Based on the simulation results, an analysis regarding the temperature distribution of a circular deposit and substrate was performed.
Findings
The FTT technique was successfully adopted in the simulation of the temperature field during the EBF3 process. The temperature bands and oscillating temperature curves appeared in the deposit and substrate.
Originality/value
The FTT technique was introduced into the numerical simulation of an additive manufacturing process. The efficiency of the process was improved, and the FTT technique was convenient for the 3D simulations and multi-pass deposits.
Details
Keywords
Li Zhao, Jianxin Sun, Ling Zhang, Pengfei He and Qiulu Yi
This study explores the effects of different types of technology lock-in on enterprise innovation performance. On this basis, the authors aim to provide technological innovation…
Abstract
Purpose
This study explores the effects of different types of technology lock-in on enterprise innovation performance. On this basis, the authors aim to provide technological innovation suggestions for the long-term development of Chinese enterprises.
Design/methodology/approach
A total of 211 high-tech enterprises in China were taken as the research sample. Data were collected through questionnaire surveys and secondhand data. Linear and nonlinear regression models were used to test the hypotheses.
Findings
Different types of technology lock-in had different effects on enterprise innovation performance. Initiative lock-in and passive lock-in showed an inverted U-shaped relationship with innovation performance. Economies of scale were positively correlated with innovation performance, while self-lock-in was negatively correlated with it.
Practical implications
This research can help enterprises reconceptualize technology lock-in. It can also help enterprises in different stages of development carry out targeted technological innovation and management strategies.
Originality/value
This research enriches our understanding of technology lock-in. By breaking with previous conceptualizations of a simple linear relationship between technology lock-in and innovation performance, this study proposes and confirms different technology lock-in has different relationships with enterprise innovation performance. This study is important for enterprises to reassess their technology lock-in state and carry out targeted technological innovation strategies. This research enriches the theory of path dependence and its combination with other theories. And this study also reveals the current research on technology lock-in is insufficient.
Details
Keywords
Jianxin Xu, Delei Du, Jian Song, Dongming Li and Yana Li
Notched fatigue life curves of welded joints were established and compared with International Institute of Welding (IIW) standards to verify the metal fatigue performance of…
Abstract
Purpose
Notched fatigue life curves of welded joints were established and compared with International Institute of Welding (IIW) standards to verify the metal fatigue performance of welded joints treated with pneumatic impact (PIT).
Design/methodology/approach
This paper was based on the notched stress method, and this approach not only allows for the assessment of fatigue failure of welded structures with toes and roots but also for the assessment of fatigue strength of joints with localized post-treatments. The paper summarizes the nominal stress data of weld and pneumatic impact treated (PIT) steel joints of different strengths, fits the nominal stress curves of the joints without the use of strength and obtains the stress concentration factor of the joints through the establishment of the finite element (FE) method. Notched fatigue life curves for welded joints were established and compared with IIW standards.
Findings
Notched stress concentration data obtained by the FE method was more reliable. The slope of the fatigue life curve of welded joints treated with pneumatic impact (PIT) increases by at least 2.5%, and the stress concentration factor decreases by 20%.
Originality/value
In the fatigue study of notched systems, there were fewer studies on fatigue life assessment of joints processed by high frequency mechanical impact. The purpose of this paper was to analyze the fatigue test data of typical strength steel welded joints and fit fatigue life curves, and the research content provides an important reference for improving the safety and fatigue failure assessment of heavy steel structures.
Details
Keywords
This paper aims to explore the relationship between environmental regulation, technological innovation and manufacturing quality competitiveness to provide some references for…
Abstract
Purpose
This paper aims to explore the relationship between environmental regulation, technological innovation and manufacturing quality competitiveness to provide some references for emission reduction activities and improvements in manufacturing quality competitiveness to achieve environmental protection targets and economic development as part of a win–win situation.
Design/methodology/approach
Based on the structure-behavior-performance paradigm and Grabowski’s research, a new empirical model was provided. The software, EViews 6.0, was used for econometric analysis. Regression analysis was adopted to explore the three indicators’ relationships.
Findings
First, environmental regulation can promote technological innovation effectively. Second, compared with wasted gas and wasted solids, investment in wasted water control promotes Chinese technological innovation most. Third, the impact of research and development investment, induced by environmental regulation, on manufacturing quality competitiveness is greater than that induced by non-environmental regulation. Fourth, the impact of lagged two-phase environmental regulation on manufacturing quality competitiveness is similar to that of lagged one-phase regulation.
Practical implications
The issue that Chinese manufacturing is facing is how to manage the trade-off between pollution control investment and improved quality competitiveness. This study enables managers to understand how to better implement environmental regulation initiatives while achieving environmental protection and quality competitiveness as part of a win–win situation.
Originality/value
This paper analyzes the relationships between environmental regulation, technological innovation and manufacturing quality competitiveness for the first time and provides the basic argument for integrating Chinese environmental regulation with quality competitiveness to reveal the uniqueness of the circumstances determining China’s economic development.
Details
Keywords
Han Sun, Song Tang, Xiaozhi Qi, Zhiyuan Ma and Jianxin Gao
This study aims to introduce a novel noise filter module designed for LiDAR simultaneous localization and mapping (SLAM) systems. The primary objective is to enhance pose…
Abstract
Purpose
This study aims to introduce a novel noise filter module designed for LiDAR simultaneous localization and mapping (SLAM) systems. The primary objective is to enhance pose estimation accuracy and improve the overall system performance in outdoor environments.
Design/methodology/approach
Distinct from traditional approaches, MCFilter emphasizes enhancing point cloud data quality at the pixel level. This framework hinges on two primary elements. First, the D-Tracker, a tracking algorithm, is grounded on multiresolution three-dimensional (3D) descriptors and adeptly maintains a balance between precision and efficiency. Second, the R-Filter introduces a pixel-level attribute named motion-correlation, which effectively identifies and removes dynamic points. Furthermore, designed as a modular component, MCFilter ensures seamless integration into existing LiDAR SLAM systems.
Findings
Based on rigorous testing with public data sets and real-world conditions, the MCFilter reported an increase in average accuracy of 12.39% and reduced processing time by 24.18%. These outcomes emphasize the method’s effectiveness in refining the performance of current LiDAR SLAM systems.
Originality/value
In this study, the authors present a novel 3D descriptor tracker designed for consistent feature point matching across successive frames. The authors also propose an innovative attribute to detect and eliminate noise points. Experimental results demonstrate that integrating this method into existing LiDAR SLAM systems yields state-of-the-art performance.
Details
Keywords
Wan Yusmawati Wan Yusoff, Norliza Ismail, Nur Farisa Nadia Mohmad Lehan, Azuraida Amat, Ku Zarina Ku Ahmad, Azman Jalar and Irman Abdul Rahman
This paper aims to investigate the effect of different doses of gamma radiation on the micromechanical response (hardness properties and creep behaviour) of 96.5Sn-3.0Ag-0.5Cu…
Abstract
Purpose
This paper aims to investigate the effect of different doses of gamma radiation on the micromechanical response (hardness properties and creep behaviour) of 96.5Sn-3.0Ag-0.5Cu (SAC305) solder alloys.
Design/methodology/approach
SAC305 solder pastes deposited on printed circuit boards (PCBs) were subjected to a reflow soldering process to form soldered samples. The soldered samples were irradiated with a gamma source at different doses (5–50 Gy). Nanoindentation testing was used to determine the hardness properties and creep behaviour after gamma irradiation.
Findings
The results showed that the hardness of SAC305 solder alloys gradually increased up to 15 Gy and then gradually decreased to 50 Gy of gamma irradiation. The highest hardness value (0.37 GPa) was observed on SAC305 solder alloys exposed to 15 Gy irradiation. Hardening of SAC305 solder alloy was suggested to be due to the high defect density induced by the gamma irradiation. Meanwhile, exposure to 50 Gy irradiation resulted in the lowest hardness value, 0.13 GPa. The softening behaviour of SAC305 solder alloy was probably due to the evolution of defect size in the solder joint. In addition, the creep behaviour of the SAC305 solder alloys changed significantly with different gamma irradiation doses. The creep rates were higher at a dose of 10 Gy up to a dose of 50 Gy. Gamma irradiation caused the SAC305 solder alloy to become more ductile compared to the non-irradiated alloy. The stress exponent also showed different deformation mechanisms with varying gamma doses.
Originality/value
Research into the micromechanical properties of solder alloys subjected to gamma irradiation has rarely been reported, especially for Sn-Ag-Cu lead-free solder. Thus, this research provides a fundamental understanding of the micromechanical response (hardness and creep behaviour) of solder, especially lead-free solder alloy, to gamma irradiation.