为了降低重型车辆液压助力转向系统(Hydraulic Power Steering,HPS)能耗并改善高速工况转向路感,提出一种用电磁离合器控制转向泵的节能型转向系统——电控液压转向系统(Electromagnetic Clutch-Electronical Controlled Hydraulic Powe...为了降低重型车辆液压助力转向系统(Hydraulic Power Steering,HPS)能耗并改善高速工况转向路感,提出一种用电磁离合器控制转向泵的节能型转向系统——电控液压转向系统(Electromagnetic Clutch-Electronical Controlled Hydraulic Power Steering,E-ECHPS)。重点分析了由主、副电机及转差功率回收装置组成的电磁离合器的结构和工作原理,并对电磁离合器进行了功率流分析,发现E-ECHPS相对于HPS具有明显的节能性。运用Ansoft软件建立了某重型车辆E-ECHPS的电磁离合器主、副电机仿真模型,并设计了主电机的外电路和副电机的驱动电路,对典型车速转向和直行工况下的电磁离合器进行仿真分析。结果表明,在转向工况下,电磁离合器的输出转矩随车速增大而减小,符合助力特性要求;在直行工况下,主电机回收的转差功率大于副电机的输入功率。电磁离合器从助力特性和能量角度均满足E-ECHPS系统的工作要求。展开更多
Pointing angle and pattern of the antenna can be changed swiftly to actualize the azimuth beam scanning by using electronic beam steering, which makes the Synthetic Aperture Radar (SAR) system more flexible and achiev...Pointing angle and pattern of the antenna can be changed swiftly to actualize the azimuth beam scanning by using electronic beam steering, which makes the Synthetic Aperture Radar (SAR) system more flexible and achieve a high resolution or cover a long strip within short time span. When the pointing angle is steered away from boresight, some aberrations may appear on the antenna pattern, e.g., the grating lobe appears, the main lobe gain decrease, and antenna pattern broadens, e.g., the aberrations result in the worsening of system performance, and complicate the corresponding performance analysis method. Conventional computation methods of performance parameters do not account for the rapid change of the antenna pattern. It introduces remarkable errors when the scanning angle is large. In this paper, a method of calculating performance parameters is proposed for the beam steering mode, which achieves the parameters by the energy accumulation in time domain. Actually, the proposed method simulates the working process of SAR and obtains accurate performance parameters. Furthermore, we analyze the effects of the grating lobe on the Azimuth Ambiguity to Signal Ratio (AASR), and present the generic Pulse Repetition Frequency (PRF) choosing principle which can also prevent the ambiguous area from weighting by the grating lobe. Finally, the effect of the antenna configuration on the performance parameters is analyzed by a system example.展开更多
A 1-bit electronically controlled metasurface reflectarray is presented to achieve beam steering with multiple polarization manipulations. A metsurface unit cell loaded by two PIN diodes is designed. By switching the ...A 1-bit electronically controlled metasurface reflectarray is presented to achieve beam steering with multiple polarization manipulations. A metsurface unit cell loaded by two PIN diodes is designed. By switching the two PIN diodes between ON and OFF states, the isotropic and anisotropic reflections can be flexibly achieved. For either the isotropic reflection or the anisotropic reflection, the two operation states achieve the reflection coefficients with approximately equal magnitude and 180°out of phase, thus giving rise to the isotropic/anisotropic 1-bit metasurface unit cells. With the 1-bit unit cells, a 12-by-12 metasurface reflectarray is optimally designed and fabricated. Under either y-or x-polarized incident wave illumination, the reflectarray can achieve the co-polarized and cross-polarized beam scanning, respectively, with the peak gains of 20.08 d Bi and 17.26 d Bi within the scan range of about ±50°. With the right-handed circular polarization(RHCP) excitation, the left-handed circular polarization(LHCP) radiation with the peak gain of 16.98 d Bic can be achieved within the scan range of ±50°. Good agreement between the experimental results and the simulation results are observed for 2D beam steering and polarization manipulation capabilities.展开更多
文摘为了降低重型车辆液压助力转向系统(Hydraulic Power Steering,HPS)能耗并改善高速工况转向路感,提出一种用电磁离合器控制转向泵的节能型转向系统——电控液压转向系统(Electromagnetic Clutch-Electronical Controlled Hydraulic Power Steering,E-ECHPS)。重点分析了由主、副电机及转差功率回收装置组成的电磁离合器的结构和工作原理,并对电磁离合器进行了功率流分析,发现E-ECHPS相对于HPS具有明显的节能性。运用Ansoft软件建立了某重型车辆E-ECHPS的电磁离合器主、副电机仿真模型,并设计了主电机的外电路和副电机的驱动电路,对典型车速转向和直行工况下的电磁离合器进行仿真分析。结果表明,在转向工况下,电磁离合器的输出转矩随车速增大而减小,符合助力特性要求;在直行工况下,主电机回收的转差功率大于副电机的输入功率。电磁离合器从助力特性和能量角度均满足E-ECHPS系统的工作要求。
文摘Pointing angle and pattern of the antenna can be changed swiftly to actualize the azimuth beam scanning by using electronic beam steering, which makes the Synthetic Aperture Radar (SAR) system more flexible and achieve a high resolution or cover a long strip within short time span. When the pointing angle is steered away from boresight, some aberrations may appear on the antenna pattern, e.g., the grating lobe appears, the main lobe gain decrease, and antenna pattern broadens, e.g., the aberrations result in the worsening of system performance, and complicate the corresponding performance analysis method. Conventional computation methods of performance parameters do not account for the rapid change of the antenna pattern. It introduces remarkable errors when the scanning angle is large. In this paper, a method of calculating performance parameters is proposed for the beam steering mode, which achieves the parameters by the energy accumulation in time domain. Actually, the proposed method simulates the working process of SAR and obtains accurate performance parameters. Furthermore, we analyze the effects of the grating lobe on the Azimuth Ambiguity to Signal Ratio (AASR), and present the generic Pulse Repetition Frequency (PRF) choosing principle which can also prevent the ambiguous area from weighting by the grating lobe. Finally, the effect of the antenna configuration on the performance parameters is analyzed by a system example.
基金Project supported by the National Key Research and Development Program of China (Grant No.2021YFA1401001)the National Natural Science Foundation of China (Grant No.62371355)。
文摘A 1-bit electronically controlled metasurface reflectarray is presented to achieve beam steering with multiple polarization manipulations. A metsurface unit cell loaded by two PIN diodes is designed. By switching the two PIN diodes between ON and OFF states, the isotropic and anisotropic reflections can be flexibly achieved. For either the isotropic reflection or the anisotropic reflection, the two operation states achieve the reflection coefficients with approximately equal magnitude and 180°out of phase, thus giving rise to the isotropic/anisotropic 1-bit metasurface unit cells. With the 1-bit unit cells, a 12-by-12 metasurface reflectarray is optimally designed and fabricated. Under either y-or x-polarized incident wave illumination, the reflectarray can achieve the co-polarized and cross-polarized beam scanning, respectively, with the peak gains of 20.08 d Bi and 17.26 d Bi within the scan range of about ±50°. With the right-handed circular polarization(RHCP) excitation, the left-handed circular polarization(LHCP) radiation with the peak gain of 16.98 d Bic can be achieved within the scan range of ±50°. Good agreement between the experimental results and the simulation results are observed for 2D beam steering and polarization manipulation capabilities.
