Aiming at the problem of excessive torque ripple of switched reluctance motor (SRM), a three-interval PWM duty cycle adaptive control strategy is proposed in this paper. The method changes the PWM duty cycle to adjust the voltage across the windings according to the torque error, divides the interval according to the inductance linear model, and adapts to different PWM duty cycles in different intervals, different speeds, and different torque errors. And the optimal PWM duty cycle group under different rotation speeds is obtained by trial and error, and this duty cycle group is used as the control method to adapt the PWM duty cycle group. Finally, through Matlab/Simulink simulation and motor platform experiments, the three-interval fixed PWM duty cycle control strategy and the three-interval PWM duty cycle adaptive control strategy in this paper are compared. The results show that the three-interval PWM duty cycle adaptive control strategy proposed in this paper has a good torque ripple suppression effect in a wide speed and wide load range.
In this paper, a dual-band ultra-wideband conformal antenna for Wireless Capsule Endoscopy is proposed. The antenna uses polyimide as a substrate of side wall to achieve conformality, leaving space for other components of the Wireless Capsule Endoscopy. The feeding network of the conformal antenna utilizes the circuit characteristics of Complementary Split-Ring Resonator to achieve dual-band operation at 1.4 GHz and 4.0 GHz. Based on the principle of wideband characteristics of spiral antennas, the conformal antenna radiation structure is improved. A short-pin is loaded at an appropriate position to improve the impedance matching of the antenna and achieve ultra-wideband without changing the resonant points of the antenna. The operating bandwidth of the antenna can reach 30.3% (1.20~1.63 GHz) and 53.3% (3.33~5.75 GHz), respectively. In addition, the antenna is placed in different simulation models to verify the stability of its operation. Minced pork is used to verify effectiveness of the conformal antenna. The measured results show that the proposed antenna is suitable for capsule endoscopy.
Multi-carrier Phase Coded (MCPC) signal has the advantages of large time-bandwidth product, low intercept, anti-jamming, digitization, flexible waveform, and high spectral utilization, and has become a hotspot in radar waveform research. However, MCPC signal has high-distance sidelobes which are difficult to suppress, after pulse compression processing. Excessive sidelobes will mask the existence of small and weak targets, thus losing the target signal, which limits the practical application of MCPC signals. Therefore, it is of great significance and practical value to study the sidelobe suppression of MCPC signals. From the point of view of waveform design, a multi-carrier phase-encoded signal combining chaotic encoding and single encoding (MCPC-CS) is designed by using chaotic sequence as phase encoding of MCPC signal and optimizing it. In this paper, peak sidelobe level ratio (PSLR) is used as a evaluation factor of the autocorrelation function. The simulation results show that MCPC-CS signal has a good autocorrelation peak sidelobe level ratio, and the autocorrelation sidelobe is reduced by more than 3 dB compared with the normal MCPC signal.
In order to solve the nonlinear couplings among speed and the radial displacement of the outer rotor coreless bearingless permanent magnet synchronous motor (ORC-BPMSM), a decoupling control strategy based on the least square support vector machine (LS-SVM) generalized inverse is proposed. Firstly, the basic structure and working principle of the ORC-BPMSM are introduced, and the mathematical model of torque and suspension forces are established. Secondly, the ORC-BPMSM system is proved reversible by establishing mathematical models and reversibility analysis, then the pseudo-linear subsystems are formed by connecting the generalized inverse system, which is identified by the LS-SVM, with the original system. Furthermore, additional closed-loop controllers are designed to improve the stability and robustness of the pseudolinear subsystems. Finally, the proposed method based on LS-SVM generalized inverse is compared with traditional inverse system method by simulations and experiments. The simulation and experiment results show that the proposed control strategy has good performance of decoupling and stability.
This paper presents a dual-polarized crossed-dipole antenna with high isolation and wide-beam radiation. The antenna comprises two orthogonal printed dipoles with single-ended and differential feeds, which are collocated on a square ground plane. The single-ended feed dipole is built on the peripheral sides of a two-layer substrate, and it is fed by a Г-shaped stripline sandwiched between the substrate layers. The differential-feed dipole is built on a single-layer substrate, i.e., the differential feed with a Π-shaped microstrip-line, and the dipole arms are printed on the top-side and back-side of the substrate, respectively. The high isolation feature is achieved by exploiting the symmetry of the design with one pair of differential feeds. The beamwidth is significantly broadened by incorporating parasitic monopole elements while keeping the design symmetrical. A realization of the design concept for the 5G NR n78 band (3.3-3.8 GHz) has been optimized, fabricated, and tested. The measured results demonstrate an impedance bandwidth of 28.6% (3.0-4.0 GHz) and port-to-port isolation of > 40 dB. Furthermore, the antenna achieves a peak half-power beamwidth of 150°/168° in the E/H planes, and a cross-polarization level of < -30 dB at the broadside direction. These features make the proposed antenna a good candidate for the 5G and in-band full-duplex applications.
In this paper, we propose a quadruple band-notched ultra-wideband (UWB) antenna with a novel virus-mimicking structure. The proposed antenna is fed by coplanar waveguide in the FR4 material. It has a compact size of 27 × 29 × 0.8 mm3. In order to reject narrowband signal interference in ultra-wideband communication, the desired notches in WiMAX (3.3-3.6 GHz), WLAN (5.1-5.8 GHz), downlink X satellite communication system (7.25-7.75 GHz), and ITU 8GHz band (8.025-8.4 GHz) are realized. Except for these, impedance bandwidth of the designed antenna is less than -10 dB from 2.5 GHz to 15 GHz, with average gain of 3 dBi. At the same time, it basically meets the omnidirectional requirement. With low profile and compact structure, the proposed antenna can be integrated into the ultra-wideband system, which can meet the requirements of ultra-wideband communication and improve the anti-interference ability of ultra-wideband communication.
This paper proposes a hybrid excited permanent magnet vernier motor for low-speed and high torque applications in electrical drive. Traditional PM vernier motors are with PM excitation field, and the air-gap magnetic field density is hard to adjust, which limit the wide speed range of PM motor. The hybrid excitation method is proposed in the PM vernier with excitation windings set in the region between modulation pole pieces. With the finite analysis method, the basic structure and the working principle of the proposed motor are introduced, and the low-speed and high-torque characteristics with wide speed range are revealed. Then, the drive control system of the motor is designed and applied with the prototype motor. Finally, the experimental results verify the reliability and effectiveness of the design theory and simulation results.
A small ring antenna working at 2.45 GHz was designed in this paper, a small disk-coupled structure was applied to feed an inner-hole-biased ring patch, contributing to not only improving the impedance characteristics of the antenna but also reducing the size. The simulation results show that the designed patch area is only 70.7% of that of the traditional circular microstrip antenna on the premise of ensuring good bandwidth and gain performance; the -10 dB bandwidth of S11 parameter is 62 MHz; the gain of the maximum direction is 7.11 dB; and the circular polarization of the antenna is also realized. This design has also been compared with several conventional designs, It is proved that the antenna has good comprehensive performance, and the antenna feed structure is simple, easy to process, very conducive to engineering applications. Finally, the feasibility of this technology was verified by contrasting the measured data with the simulation data.
In this work we demonstrate the extended and generalized methodology for the design of Quad-Furcated Profiled Horns (Q-FPHs). Based on a design case of a 4λ0×4λ0 Q-FPH, we extract the Generalized Scattering Matrix (GSM) of the enlarged quad-furcated discontinuity and provide analytical expressions for its multimode feeding. Next, the four feeding and the upper common waveguide sections are optimized accordingly through Mode-Matching (MM). The high aperture efficiency levels delivered by the methodology are verified by full-wave simulations of the optimized design case and compared to the state-of-the-art which is thereby redefined.