Hybrid Modulation Research Articles

A Novel System of Mixed RF/FSO UAV Communication Based on MRR and RIS by Adopting Hybrid Modulation

In this paper, we propose a mixed radio frequency (RF)/free space optical (FSO) unmanned aerial vehicle (UAV) communication system, based on modulating retro-reflector (MRR) and reconfigurable intelligent surface (RIS), which adopts the hybrid L-ary pulse position modulation-binary phase shift keying-subcarrier intensity modulation (L-PPM-BPSK-SIM). More specifically, the RF channel follows Rayleigh distribution, while the FSO channel obeys Gamma–Gamma distribution that considers atmospheric turbulence and pointing error. For decode-and-forward (DF) relay, the MRR is installed on the UAV to reduce its weight, size, and power consumption. In particular, the RIS is used as user terminal along with the RF signal generator to achieve signal enhancement. Based on this, closed expressions for the outage probability, average bit error rate (BER) and average channel capacity of the end-to-end uplink and downlink are derived. Numerical results confirm that while the relay limitation is solved by MRR, RIS significantly reduces the outage probability and average BER as well as obviously increases the average channel capacity. Furthermore, the hybrid L-PPM-BPSK-SIM with average symbol length greater than eight can effectively improve the average BER performance of the system.

Design and Development of a 2 × 2 Array Piezoelectric–Electromagnetic Hybrid Energy Harvester

Energy harvesting technology is regarded as a feasible solution for the continuous power supply of microelectronic devices. Efforts have been made to improve the output power of all kinds of energy harvesting devices. This paper reports a 2 × 2 array piezoelectric–electromagnetic hybrid energy harvester that achieves high power output through the combination of piezoelectric and electromagnetic conversion. The harvester included four piezoelectric–electromagnetic hybrid modules, each of which consisted of a piezoelectric sheet, a permanent magnet and a wound coil. The permanent magnet, also serving as the mass block of the cantilever beam when subjected to external stimulus, contributed to a large displacement of the vibration and generated high output power. At an acceleration of 1 g and a resonance frequency of 70.4 Hz, the measured maximum output power of the hybrid energy harvester was 66.08 mW, of which the piezoelectric and electromagnetic portions were 56.96 and 9.12 mW, respectively. Furthermore, in a charging experiment, a capacitor of 23.5 mF was charged to 11.5 V within 20 s, which demonstrates a practical application of the hybrid energy harvester for microelectronic devices.

Resonant Power Supply for Plasma Cleaning Based on Fuzzy Logic Power Tracking

The coaxial cylindrical reactor with a rotary nozzle is proposed to be used as the plasma torch of the plasma cleaning machine. The phase-shifted full bridge series resonance circuit is used as the power circuit topology. Because the voltage source load resonance circuit technology is mature, the cycle and difficulty of research and development on this basis are relatively small, and the corresponding control strategy and algorithm are relatively easy to achieve. At the same time, the voltage source circuit is smaller than the current source circuit, in line with the development trend of plasma cleaning equipment. In this paper, based on the phase shift full bridge series resonant circuit, the control strategy is compared and analyzed. Considering the response speed, control precision and efficiency, a PSPWM-PFM (Phase Shift Pulse Width Modulation- Pulse Frequency Modulation) hybrid modulation control strategy is proposed, which makes the system not only have a fast response speed but can also construct a soft switch and has a high efficiency. A maximum power tracking algorithm based on a fuzzy PFM was proposed to solve the problem that the plasma power supply deviated from the resonant frequency point easily due to environmental perturbation, and thus deviated from the maximum power point.

Output-Controllable Efficiency-Optimized Wireless Power Transfer Using Hybrid Modulation

This article proposes and implements an output-controllable efficiency-optimized wireless power transfer scheme using hybrid modulation. The key is to combine pulse frequency modulation (PFM) and <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on-off</small> keying (OOK) modulation and to utilize feedback control. Among them, PFM is used for the output voltage regulation of the inverter to adjust the rectified output voltage on the receiver side, while OOK modulation is adopted to convert the load resistance to be close to the optimal resistance value so that the system efficiency can be effectively optimized. When the relationship between the input and output voltages reaches a ratio related to system parameters, it can be considered that the load resistance has reached the optimal state. Hence, the feedback output voltage is utilized to help convert the load resistance into an optimal value and only one voltage acquisition circuit is needed. In this article, theoretical analysis and practical experimentation (using the LED lamp as a nonlinear load and the 102-Ω resistance as a linear load) are both given to verify that the proposed scheme can help to maintain high system efficiency during the output voltage regulation process.

Hybrid-Modulation-Based Full-Speed Sensorless Control for Permanent Magnet Synchronous Motors

This article presents a full-speed sensorless control strategy for permanent magnet synchronous motors (PMSMs) based on a hybrid modulation strategy. The motor operating condition is divided into three ranges: low-speed range, transition range, and high-speed range. A novel two-or-three-vector switching (TTVS) method for rotor position demodulation based on an optimized asymmetric pulsewidth modulation (OAPWM) is proposed in the low-speed and transition regions. A Luenberger position observer based on the conventional symmetric space vector pulsewidth modulation is adopted to demodulate the rotor position in the high-speed region. Additionally, a switching strategy of two modulations and two position estimation observers is proposed to achieve a smooth speed and current transition. Compared with the previous work, the benefits of the TTVS method are to extend the modulation index of the OAPWM and to improve the position estimation accuracy. Finally, the feasibility of the proposed full-speed sensorless control is verified in a 500-W PMSM drive.

All-SiC Traction Converter for Light Rail Transportation Systems: Design Methodology and Development of 165 kVA Prototype

The design and development of a high-performance 165 kVA, 750 V DC all-silicon carbide (SiC) traction converter for new generation light rail transportation systems (LRTSs) are described. In the design of the traction motor drive, the efficiency of the overall system is maximized and the line current harmonic content of the traction motor is minimized. A complete mathematical model of the physical system is derived to carry out real-time simulations and proper control of the LRTS on a real rail track. The electrical and thermal performances of traction-type SiC power MOSFET modules are compared with those of alternative hybrid and Si-IGBT modules for various switching frequencies. The implementation of the developed system is also described. The performance of the resulting system is verified experimentally on a full-scale physical simulator as well as for various track conditions. Very promising results for the next generation railway traction motor drives have been obtained in terms of performance criteria, such as very high efficiency, low harmonic distortion of the motor line current, low cooling requirement, relatively high switching frequency, and hence, superior controller performance. The effects of the SiC power MOSFET operation on the insulation of the available traction motors are also examined experimentally. This paper is accompanied by a video demonstrating the experimental work.

Development of MXene / WO 3 embedded PEDOT : PSS hole transport layers for highly efficient perovskite solar cells and X‐ray detectors

A simple solution process was employed to decorate WO3 nanoparticles on 2D conductive Ti3C2TX MXene sheets to arrange the MXene/WO3 hybrid structure. The prepared hybrid composites were established by the Raman scattering, X-ray diffraction, and microscopy studies evidently. The designed hybrid structure, for the first time, was engaged with PEDOT:PSS to alter the hole transport layer (HTL) of perovskite hybrid module for the highly efficient planar solar cell and X-ray detector. The derived outcomes revealed a high power conversion efficiency of 12.26 ± 0.12% for the constructed perovskite solar cell with MXene/WO3/PEDOT:PSS HTL. Similarly, the fabricated X-ray photodetector with MXene/WO3 blended HTL device attained a superior sensitivity of 3.67 ± 0.03 mA Gy−1·cm−2. The results envisaged that HTL/perovskite interface was effectively tuned by the MXene/WO3 heterostructure through their active interface for transfer/collection of charges and appropriately altered energy band alignment, which gave the nod for easy to charge extraction and shortest charge carrier lifetime.

Modeling and Prototype of a Machining Robot With R(3-RUHR)/UURP Hybrid Module

Abstract Hybrid mechanisms combine the advantages of serial mechanisms and parallel mechanisms and have better stiffness and a larger workspace. In this paper, a novel workspace strongly coupled machining robot mechanism with a hybrid module is proposed. It is composed of a four-degrees-of-freedom (4DOF) R(3-RUHR)/UURP hybrid module and a 2-DOF (RRRP)R single-closed-loop serial rotation module, which has the advantages of small footprint, large workspace, high stiffness, and is ideal for machining robots applied to modular integrated manufacturing lines. However, due to the multi-closed loop between azimuth pitch rotations and hybrid module, the workspace is coupled, so that the mechanism has problems in building the forward and inverse position, kinematics, and dynamics analytical models, numerical solution calculation speed, and multi-solution. Based on the analysis of coupled characteristics of this mechanism, the concomitant motion neural network (NN) models of the 3-RUHR parallel mechanism and inverse position NN models of the (R(3-RUHR)/UURP)(RRRP)R hybrid robot are established using the Levenberg–Marquardt training algorithm with Bayesian regularization. Furthermore, the kinematics and dynamics models of the proposed hybrid robot are established using the equivalent screw method. And the correctness of position NN models, kinematics complete model, and dynamics complete model are verified through numerical examples, respectively. Finally, the prototype of this hybrid robot is further developed, and the coupled motion and multi-axis machining capability of the (R(3-RUHR)/UURP)(RRRP)R hybrid machining robot are verified by experiment. The hybrid mechanism and modeling method proposed in this paper can provide support for the application of machining robots with a small footprint, strongly coupled large workspace, and high stiffness.

Innovation of Using Hybrid Modules in Muhammadiyah Elementary School in Sleman as Alternative Distance Learning Solutions in the Covid-19 Pandemic

The pandemic has turned the education and learning process into distance learning and learning from home. These changes do not necessarily run smoothly. However, there are many obstacles and problems. These include internet network access, the absence of quotas and the process of changing without being conditioned before. Not to mention the complaints from parents who usually leave it entirely to the school, but with the pandemic, parents seem to be "forced" to be involved in the distance learning process. One of the innovations developed by the Muhammadiyah School in Sleman at the elementary and junior high school levels is using a hybrid module. This research is a descriptive qualitative research on the application and effectiveness of the hybrid module among students of SD Muhammadiyah SMP in Sleman Regency. The number of respondents who were given a questionnaire on the implementation and effectiveness of the module was selected to represent all sub-districts in Sleman Regency, totalling 17 sub-districts. So that the number of research targets consists of 34 principals, students, and parents of students from all Muhammadiyah elementary schools throughout Sleman Regency, totalling 98 respondents. The results of the study reveal the innovation of the Hybrida module at Muhammadiyah Middle School in Sleman as an alternative to Distance Learning solutions during the Covid-19 pandemic in Sleman Regency. All 15,407 Muhammadiyah elementary school students and 9,063 Muhammadiyah junior high school students use the module as a learning resource for teachers, students and parents and guardians of students. The effectiveness of the innovation of using Hybrid Modules at Muhammadiyah Middle School in Sleman as an Alternative to Distance Learning Solutions During the Covid-19 Pandemic, there were many benefits. The benefits of hybrid modules are also discussed in this article.

Assessment of a hybrid UV-LED-membrane distillation process: Focus on fouling mitigation

This study aimed to manufacture a hybrid UV-LED and membrane distillation module (UV-LED-MD) for the first time. Its performance in wastewater post-treatment was evaluated, and the effect of UV-LED on membrane fouling was investigated. The removals of 17α-ethynylestradiol and estrogenic activity in the hybrid module were also assessed. In preliminary tests, flux tended to stabilize at an average value of 3.1 and 3.5 L m−2 h−1 in MD and UV-LED-MD, respectively. When treating wastewater, MD and UV-LED-MD presented similar performances. P-PO43- removal was higher in UV-LED-MD. The hybrid module and MD had similar performance in hormone removal efficiencies (>97.7%) and estrogenic activity removals (>99.0%). The membrane from UV-LED-MD was less fouled according to visual inspection. However, the UV-LED-MD membrane exhibited a greater flux decline. The fouling layer in UV-LED-MD was much less adhered to the membrane. The lower adhesion of the fouling to the membrane means a great practical operational advantage, which justifies further investigations into the UV-LED and MD coupling.

Improved Model Predictive Control for Three-Phase Dual-Active-Bridge Converters With a Hybrid Modulation

In this paper, an improved moving discretized control-set model predictive control (MDCS-MPC) with a hybrid modulation is proposed for 3p-DAB. The main objectives of this paper are to improve the efficiency in partial-load and to enhance dynamic performance for output voltage tracking. Firstly, the hybrid modulation, which consisted of triangular modulation, trapezoidal modulation as well as phase-shift modulation, can extend the soft-switching range and improve the efficiency for 3p-DAB, especially in light load conditions. Meanwhile, the closed-form of analytic expression of the hybrid modulation is derived and presented in the form of a simple table. Next, the designed hybrid modulation is incorporated into the proposed MDCS-MPC methodology to enhance the transition response for output voltage tracking. Furthermore, a proportional-integral observer is utilized to estimate the load current for the cost-saving of the current sensor. The main contribution of the proposed methodology relies on the fact that the dynamic response for output voltage tracking can be improved, the current stress can be reduced in light load, and the cost of the system can be saved. Finally, comparison experiments on a laboratory prototype are carried out to confirm the theoretical analysis and the performance improvement of the developed approach.

A Probabilistic Shaping Approach for Optical Region-of-Interest Signaling

We propose a probabilistic shaping approach for region-of-interest signaling, where a low-rate signal controls the desired probabilistic ranges of a high-rate data stream using a flexible distribution controller. In addition, we introduce run-length-aware values for frozen bit indices in systematic polar code to minimize the run-length without using run-length-limited code. Our compact system can support soft-decision forward-error-correction decoding with excellent spectral efficiency compared with related work based on hybrid modulation schemes.

A NOVEL HYBRIDIZATION OF SEAGULL ALGORITHM AND COMBINED COMPROMISE SOLUTION (SOA–CoCoSo) IN DRILLING INVESTIGATION OF CARBON NANO-ONION-MODIFIED POLYMER COMPOSITES FOR STRUCTURAL APPLICATION

Carbon nanomaterial (CNM)-reinforced polymer composite is broadly employed in emergent industrial needs due to advanced mechanical properties. In this research paper, a comparatively innovative integrated approach (SOA–CoCoSo) is proposed by using Principal Component Analysis (PCA)-based Combined Compromise Solution (CoCoSo) and Seagull Optimization Algorithm (SOA). This modified module is used in the drilling operation of zero-dimensional (0D) carbon nano-onion (CNO)-reinforced polymer (epoxy) composite. The desired machining performances, namely, surface roughness ([Formula: see text]), thrust force (Th), and Torque (Tr), are optimized to improve the quality and productivity concerns. The control of process constraints, i.e. the wt.% of nanomaterial ([Formula: see text]), spindle speed ([Formula: see text]), and feed rate ([Formula: see text]), was performed to achieve the desired objective value. The drilling experimentation was executed at three different levels of Box–Behnken Design (BBD). The objective function of PCA–CoCoSo was fed as input into the SOA. To acquire a better work efficiency, higher spindle speed, lower feed rate, and incremental wt.% of nanomaterial reinforcement are considered. The results demonstrated that the wt.% of CNO reinforcement and feed rate are the most influential factors for optimal machining performance results. The optimal constraints condition from the SOA–CoCoSo hybrid module is found at a combination of lower level of CNO wt.% (0.5[Formula: see text]wt.%) and feed rate (61[Formula: see text]mm/min) and high value of spindle speed (1500[Formula: see text]rpm). Also, the hybrid SOA–CoCoSo module shows a lesser amount of error percentage than the usual PCA–CoCoSo. The experiments were performed to confirm the feasibility of the suggested hybrid module for optimizing the varying machining parameters. The results indicated that the hybrid method is more efficient than the conventional method.

A Compensation Component Injection Method Based on a Hybrid Modulation for Minimizing the Neutral-Point Voltage Oscillations in a Five-Level Flying Capacitor Rectifier

Neutral-point (NP) voltage oscillating is an inherent problem for multilevel converters with split dc-link capacitors. In this article, a compensation component injection method based on a hybrid modulation for minimizing the NP voltage oscillations in a five-level flying capacitor rectifier is proposed. In specific, the equivalent modulation waves are first obtained by adopting an existing simplified space-vector modulation method. And a hybrid modulation which gives both the same optimal harmonic performance as phase-disposition pulse width modulation (PWM) and the same superiority of flying capacitor voltage regulation as phase-shifted PWM is adopted. Meanwhile, the solved optimal compensation component in each subsector is injected to make the average NP current equal to zero for minimizing the NP voltage oscillations. Simulations and experiments were conducted to verify the performance of the proposed compensation method based on the hybrid modulation.

A Generalized Scheme With Linear Power Balance and Uniform Switching Loss for Asymmetric Cascaded H-Bridge Multilevel Inverters

Under the traditional hybrid modulation strategy, the output voltage of 2:1:1 asymmetric cascaded H-bridge multilevel inverter is proved to be of high quality. However, the cascaded cells operate in unbalanced power regime and the switching loss of low-voltage cells is extremely uneven. To resolve the mentioned problems, the average power of cascaded cells is analyzed and the internal mechanism of power imbalance is revealed. Based on this, a power balance modulation strategy is proposed in this article. The modulation strategy effectively equalizes the switching loss of cells H2, H3 by modifying the triangular carriers, and then controls the conducting angle of cell H1 achieving a balanced power distribution among cascaded cells under the full modulation indexes. Compared with the existed modulation strategies, the proposed method has the merits of easy implementation, good dynamic performance, balancing low-voltage cells switching loss, and linearizing output power of cascaded cells. In addition, the modulation strategy also offers a generalized scheme, which can achieve a balanced power distribution among cascaded cells with an asymmetric ratio of i:1:1:1…. Finally, the simulation and experiment results confirm the feasibility of the modulation strategy under changes in modulation index and load.

Hybrid SiC-Si DC–AC Topology: SHEPWM Si-IGBT Master Unit Handling High Power Integrated With Partial-Power SiC-MOSFET Slave Unit Improving Performance

Based on partial power conversion concept, this article proposes a hybrid silicon carbide (SiC)-silicon (Si) dc–ac topology to improve performance in high power application. First, master unit (MU) uses Si-IGBT working in low frequency to handle main high power because of its high rated current capacity and high switching loss, whereas the low power quality of MU is induced by the low switching frequency. And SiC-MOSFET suffers from high cost and high conduction loss at high power level. To solve these problems, the partial-power slave unit (SU) based on SiC-MOSFET is connected with MU in series through line-frequency transformer, whereas SU works in high frequency to compensate the harmonic of MU and adjusts the total output voltage. In this new topology, the corresponding hybrid modulation strategy and multiple quasi-proportional-resonance control for single-phase system are introduced in detail to ensure the reliable operation. In the end, a 4.5-kW converter prototype was implemented and tested. Simulation and experiment results are given to verify the performance of the proposed hybrid dc–ac topology.

A Time-Domain-Model-Based Digital Synchronous Rectification Algorithm for CLLC Resonant Converters Utilizing a Hybrid Modulation

For bidirectional <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLLC</i> resonant converters, synchronous rectification (SR) is a key technique that can reduce the conduction losses in rectifying side by replacing the diodes with the switches’ channel. However, existing methods suffer from either complex hardware, or incomplete and imprecise control effect. Aiming at solving these problems, this article proposes a digital sensorless SR algorithm based on the time-domain model under a hybrid modulation for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLLC</i> converters. The proposed approach can precisely enable the SR drive action within almost the whole load range and without any additional hardware, e.g., antiparallel diode, SR IC, and high bandwidth sensor. Its implementation only needs to measure dc signals (e.g., the output current), rather than any high-frequency resonant signals. Additionally, the presented algorithm can be easily implemented on a digital controller. Finally, experiments have been performed on a prototype to verify the validity and applicability of the presented SR algorithm.

A Hybrid Modulation Featuring Two-Phase Clamped Discontinuous PWM and Zero Voltage Switching for 99% Efficient DC-Type EV Charger

Two-stage AC-DC converters are considered as a prominent solution for DC-type electric vehicle (EV) chargers. However, this kind of architecture suffers from high switching losses with large heatsink and DC-link capacitor volume. To relieve this issue, this paper presents a new hybrid modulation for DC-type EV chargers, where a two-phase clamped discontinuous pulse-width-modulation (DPWM) in the front-end circuit is cooperated with the variable frequency triangular-current-mode (TCM) zero voltage switching (ZVS) or its simplified implementation, i.e., boundary-ZVS (B-ZVS) strategy, in the back-end circuit. The former can stop the switching actions in the front-end stage during two-thirds of the grid period, while the AC currents are at their highest values, which can yield to the best switching loss reduction and deliver high power factor operation. Besides, TCM-ZVS or B-ZVS modulations can achieve ZVS turn-on action for all semiconductors during all operating range in the DC-DC stage to further reduce the power losses on the semiconductors. With such characteristics, the proposed strategies can reduce the switching losses of the system to the best extent, and thus allow an enhancement of the system power density by improving the power conversion efficiency. The proposed strategy is described, analyzed, validated, and benchmarked in a 5 kW SMD SiC MOSFET-based two-stage AC-DC converter. A 99% power efficiency can be achieved with the solution implementing the TCM-ZVS strategy at an output voltage of 400 V and rated power.

Operation and Efficiency Analysis of a Five-Level Single-Phase Hybrid Si/SiC Active Neutral Point Clamped Converter

The ability to improve both the size and efficiency of multilevel single-phase converters is a key to uplift them as an attractive solution for industries, while the high number of switches and complex modulation techniques understandably make them unattractive. Five-level active neutral point clamped (ANPC) converter, due to its inherent advantages such as employing different switching frequencies and using different switch technologies, presents an ideal candidate for study. This article performs a comprehensive analysis of the converter to highlight the advantages of it. This analysis results in a modified hybrid modulation that effectively regulates the neutral point (NP) of the dc link. Consequently, the combination of the topology and the modified modulation make the converter ideal to utilize two different switch technologies—in this article, silicon carbide (SiC) and Si MOSFET. To evaluate the analysis and the effectiveness of modulation, a 2-kW hybrid five-level ANPC is built. The converter current behavior is analyzed to determine the power loss in the filter and switches. The efficiency measurement is performed and compared with the calculated efficiency. There is a close coherency between the measurement and the calculated results and a peak efficiency of 98.4% is achieved.

Outcomes of Gender Affirming Voice Training: A Comparison of Hybrid and Individual Training Modules.

Gender affirming voice training supports individuals as they explore and develop a healthy voice that feels congruent with their gender and sense of self. Although gender affirming voice training is increasingly available, there is no research comparing individual versus hybrid training outcomes in the existing literature. A retrospective chart review was performed on trans women and/or nonbinary individuals who attended either individual or hybrid (group and individual training) gender affirming voice and communication training at St. Michael's Hospital in Toronto between 2012 and 2019. Participant demographics, self-reported goal achievement, attendance, pre/post-Trans Woman Voice Questionnaire (TWVQ) scores, and pre/postspeaking fundamental frequency (SFF) were compared between individual and hybrid training participants. Multiple logistic regression analysis was performed to determine factors that could predict self-reported goal achievement. Sixty-two trans women and/or nonbinary individuals who attended either individual (n = 43) or hybrid (n = 19) gender affirming voice and communication training were included in the study. Hybrid participants had a significantly higher goal achievement rate and therapy adherence rate compared with individual participants (74% vs. 21%; 84% vs. 28%, respectively). Both training models resulted in significant elevation of SFF and reduction of TWVQ scores. Inflection range did not change significantly for either training formats. Multiple logistic regression showed that hybrid training was a positive predictor for goal achievement (odds ratio = 2.2, 95% confidence interval [0.3, 4.1]). Although clients in individual and hybrid gender affirming voice and communication training achieved significant pitch elevation and lower TWVQ scores, hybrid participants demonstrated significantly higher goal achievement and therapy adherence. This study suggests that hybrid training may provide a valuable support system that improves therapy success in this client population.