Passively Q-switched dual-wavelength Yb：LSO laser based on tungsten disulphide saturable absorber

We demonstrate a passively Q-switched Yb：LSO laser based on tungsten disulphide （WS2） saturable absorber op- erating at 1034 nm and 1056 nm simultaneously. The saturable absorbers were fabricated by spin coating method. With low speed, the WS2 nanoplatelets embedded in polyvinyl alcohol could be coated on a BK7 glass substrate coated with high-refractive-index thin polymer. The shortest pulse width of 1.6 gs with a repetition rate of 76.9 kHz is obtained. As the pump power increases to 9 W, the maximum output power is measured to be 250 mW, corresponding to a single pulse energy of 3.25 μJ. To the best of our knowledge, this is the first time to obtain dual-wavelength Q-switched solid-state laser using few-layer WS2 nanoplatelets.

Mode switching control strategy of dual motors coupled driving on electric vehicles

Based on analyzing the structure and working principle on electric vehicles （EVs） with dual motors coupled by planetarY gears, the control strategy of mode switching was proposed. The power interruption problem on EVs with automatic mechanical transmission （AMT） shifting was resolved. Based on the speed-torque characteristics of the planetary gears and the principle of the auxiliary motor＇ s zero speed braking, control features of mode switching were introduced. The mode shifting between the main motor mode and dual motors coupled driving were studied. Matlab/Simulink was adopted as a platform to develop the simulation model of EVs with dual motors drive system and 3 gears AMT. Simulation results demonstrated that the power interruption of dual motors drive system was solved during mode switching. The power requirements of EVs were satisfied, too.

Effects of Direct Switching Dual Bronchodilators between Dry Powder and Soft Mist Inhalers in COPD Patients

Objective: Dual bronchodilation with long-acting muscarinic antagonist and long-acting β2-agonist combinations are available worldwide in COPD patients. However, the choice of agents remains under debate. We hypothesized that switching devices between dry powder and soft mist inhalers without a wash-out period to mimic clinical practice would improve clinical symptoms and lung function. The aim of this study was to examine the effects of switching between once-daily glycopyrronium/indacaterol (GLY/IND) or umeclidinium/vilanterol (UMEC/VI), dry powder inhalers, and tiotropium/olodaterol (TIO/OLO), a soft mist inhaler, in COPD patients. Methods: This was a prospective, open-label, 8-week, observational study with follow-up. Subjects included 57 COPD patients, who attended outpatient clinics at Shizuoka General Hospital for routine check-ups between February and December 2015, receiving GLY/IND (50/110 μg) or UMEC/VI (62.5/25 μg). After an 8-week run-in period, medications were switched to TIO/OLO (5/5 μg). Study outcomes included patient’s global rating (PGR), modified MRC (mMRC), COPD assessment test (CAT), and spirometric and forced oscillatory parameters after 8 weeks. PGR used in this study was a 7-point scale ranging from 1 to 7, with 4 in the middle. Patients who consented to switch from TIO/OLO to GLY/IND or UMEC/VI were followed-up thereafter. Results: In total, 53 patients completed the study (mean age, 75 years;48 males and 5 females;GOLD 1/2/3/4 = 19/27/6/1;mMRC 0/1/2/3/4 = 14/22/12/4/1;UMEC/VI 26, GLY/IND 27). PGR, mMRC, and CAT improved in 20 (38%), 9 (17%), and 15 patients (28%), respectively. Respiratory system resistance at 5 Hz (R5), 20 Hz (R20), and the difference between R5 and R20 (R5 - R20) significantly improved. In a follow-up of 16 patients after switching from TIO/OLO to UMEC/VI (9) or GLY/IND (7), PGR, mMRC, and CAT improved in 5 (31%), 3 (12%), and 4 patients (25%), respectively, and R20 significantly improved (p = 0.011). Conclusions: Switching dual bronchodilators between dry powder and soft mist inhalers improves symptoms and airway narrowing in some COPD patients.

Electro-optical dual modulation on resistive switching behavior in BaTiO3/BiFeO3/TiO2 heterojunction

The novel BaTiO3/BiFeO3/TiO2 multilayer heterojunction is prepared on a fluorine-doped tinoxide(FTO) substrate by the sol–gel method. The results indicate that the Pt/Ba TiO3/BiFeO3/TiO2/FTO heterojunction exhibits stable bipolar resistive switching characteristic, good retention performance, and reversal characteristic. Under different pulse voltages and light fields, four stable resistance states can also be realized. The analysis shows that the main conduction mechanism of the resistive switching characteristic of the heterojunction is space charge limited current(SCLC) effect. After the comprehensive analysis of the band diagram and the P–E ferroelectric property of the multilayer heterojunction, we can deduce that the SCLC is formed by the effect of the oxygen vacancy which is controlled by ferroelectric polarizationmodulated change of interfacial barrier. And the effective photo-generated carrier also plays a regulatory role in resistance state(RS), which is formed by the double ferroelectric layer Ba TiO3/BiFeO3 under different light fields. This research is of potential application values for developing the multi-state non-volatile resistance random access memory(RRAM) devices based on ferroelectric materials.

Demonstration of Orbital-Angular-Momentum-Based Optical Switching Using Dual-Area Mirrors

We have designed an optical separation device called dual-area mirror for the data link of orbital angular momentum (OAM) multiplexing. Experiments show that the OAM multiplexed beams can be switched by using dual-area mirrors, using OOK to modulate four channels separately to form two inputs, channel A and channel B. There are two OAM beams that are multiplexed in each of channel A and channel B, using a spatial light modulator (SLM) to convert the OAM multiplexed beams in each channel. One of the beams is converted into a Gaussian beam, and then separated by a dual-area mirror, so as to realize the switch of a beam carrying different data in the two channels. Then these channels are detected. The waveform indicates that the switch is successful, and the measured optical power indicates that the dual-area mirror can reduce the bit error rate in the communication links. In addition, the device reduces the experimental cost, is easy to implement, is easy to integrate, and increases the angle between the separated beams.

A Novel Dual-Rate Sampling Switched-Capacitor Configuration and Its Application

In order to realize accurate bilinear transformation from s- to z-domain,a novelswitched-capacitor configuration is proposed in the light of principles of dual-rate sampling and chargeconservation,which has also been used for building a 5th-order elliptic lowpass filter.The filter issimulated and measured in typical 0.34 μm/3.3 V Si CMOS process models,special full differentialoperational amplifiers and CMOS transfer gate switches,which achieves 80 MHz sampling rate,17.8MHz cutoff frequency,0.052 dB maximum passband ripple,42.1 dB minimum stopband attenuation and74 mW quiescent power dissipation.At the same time,the dual-rate sampling topology breaks thetraditional restrictions of filter introduced by unit-gain bandwidth and slew rate of operational amplifiersand also improves effectively their performances in high-frequency applications.It has been applied forthe design of an anti-alias filter in analog front-end of video decoder IC with 15 MHz signal frequencyyet.

一种新型无桥Dual-Boost PFC软开关控制技术

研究了一种非最小电压应力无源无损PWM变换器,与具有最小电压应力的PWM变换器相比,它具有电流应力更小、效率更高的优势。分析了非最小电压应力的无源无损电路网络在无桥Dual-Boost功率因数矫正(Power Factor Correction,PFC)的工作模态,并且给出了相应的参数设计。仿真结果证实了方案的可行性。

一种新型无桥Dual—boostPFC软开关技术研究

本文研究了一种非最小电压应力无源无损软开关PWM变换器，与具有最小电压应力的PWM变换器相比，它具有电流应力更小，效率更高的优势。作者分析了非最小电压应力无源无损电路网络的无桥Dual—Boost功率因数矫正（Power Factor Correction，PFC）变换器的工作模态，并且给出了相应的参数设计。仿真结果证实了该方案的可行性。

基于双剔除门限的Switching-CFAR目标检测算法

为了解决传统的目标检测算法在非均匀噪声环境下检测性能严重下降的问题,提出了一种基于双剔除门限的Switching-CFAR(switching-constant false alarm rate based on dual censoring thresholds,DCS-CFAR)目标检测算法。基于参考窗参考单元样本期望值和测试单元,得到双重剔除功率比较门限。通过双重比较,剔除参考窗中极大值参考单元,根据剩余参考单元数,选择合适的参考单元来估计背景噪声功率,并得到功率检测门限。在Matlab环境下,通过蒙特卡洛方法和Swerling II模型对DCS-CFAR目标检测算法的关键参数,以及在各种仿真环境下与其它目标检测算法的检测性能进行了仿真对比分析,DCS-CFAR目标检测算法在均匀背景噪声下,检测率为98.76%,接近于CA-CFAR算法;在杂波和多干扰目标环境下,检测率分别为97.83%和98.23%。在均匀和非均匀噪声环境下,DCS-CFAR检测算法均优于ACCA-CFAR和GO-CFAR算法。结果表明,提出的DCS-CFAR检测算法在均匀和非均匀噪声环境下,均具有良好的检测性能。

动态无线充电系统自解耦型分段导轨及其双模切换策略研究

为抑制电动汽车动态无线充电系统发射单元间的交叉耦合,降低其对系统谐振参数设计的影响,文中利用螺线管线圈与平面线圈正交解耦特性,提出一种自解耦分段发射导轨,其中螺线管为分级叠层绕制,实现了相邻发射单元间的自解耦。为降低系统输出参数波动,基于互感动态变化规律,确定系统最佳充电区间,并提出一种双模工作模式及其分段切换策略,实现对发射线圈实能顺序的实时控制。为实现双模工作状态的有序变换,设计自解耦检测线圈结构,该检测线圈采用单层螺线管绕制并与接收线圈正交,避免检测信号与电能传输之间的干扰。最后,搭建实验平台对所提方法的有效性进行验证。实验结果表明,系统输出功率平稳性提升了19.5%,系统的最高效率可达92.3%。

Analysis and Implementation of Dual-ZCS forward DC/DC Converter

As the switching frequency in DC/DC converter increases, original ‘hard-switch’ working mode is not compatible. Another problem is the reliability, which is puzzled in single-ended forward, push-pull or bridge-like structures. In this paper, a new dual-ZCS (zero current switches) forward topology is proposed. The operating principle of soft-switch is analyzed, showing the relationship between voltage and current in time domain. Then how to calculate the key parameters of resonant network is . Finally, a prototype ZCS SMPS is implemented and tested. The results consisted with the analyzing results well, and illustrated the advantages of the proposed structure.

A digital controlled alternating electromagnetic stirring generator based on dual inverter structure

A digital controlled alternating electromagnetic stirring generator is proposed in this paper. The main circuit of the generator makes use of dual inverter structure among which the former inverter uses full bridge zero voltage switching topology and the latter inverter uses full bridge inverter circuit. To improve the dynamic response performance, the inverting frequency of the former inverter is as high us 100 kHz. The Cortex-M3 kernel based ARM microcontroller LM3S818 is adopted as the cybernetics core of the digital control system to achieve accurate, stable and flexible control of the generator. All the PWM signals for the former and latter inverters are generated by the LM3S818 directly. The constant current characteristic of the former inverter is obtained through current close-loop feedback control, and can ensure the operation safety when the output current waveform is at zero crossing point. Both simulation and experiment results show that the proposed generator is with such advantages as wide soft-switching range, perfect control accuracy and flexible waveform modulation, and can fulfill the requirements of electromagnetic stirring process.

轻载工况下基于效率优化的双向无线电能传输系统半桥调制策略

针对基于全桥拓扑的双向双LCC无线充电系统调制策略在轻载工况下功率因数和效率下降严重的问题,该文在不改变全桥结构的基础上,提出一种半桥调制策略。首先对双向双LCC补偿电路进行通态效率建模,并定量分析影响效率的关键变量及其约束条件,从而为调制策略的优化提供理论依据;在此基础上,对所提双边半桥调制策略的工作原理、正导通角优化关系及软开关实现条件进行详细分析,证明该策略在保证开关器件零电压导通的同时,可显著减小外移相角,从而有效提高系统的功率因数和运行效率;最后,搭建3.3 kW的双向无线电能传输系统样机进行对比实验,实验结果表明,所提半桥调制策略在1/4满载及以下的轻载工况下效率最高可达95.6%,且在输出电压宽范围变化时都能够取得明显的优化效果。

小偏差永磁同步电机双矢量模型预测控制

传统的永磁同步电机双矢量模型预测控制的合成电压矢量与参考电压矢量的偏差较大,且存在计算量大、开关频率高的缺点,在实际工况中难以实现良好的控制性能。为了解决上述问题,提出一种小偏差永磁同步电机双矢量模型预测控制策略,通过分析参考电压矢量的变化规律,构造新的电压矢量选择表,将电压矢量的选择范围从六个降为三个,减小计算量的同时也降低了开关频率;针对传统的作用时间计算方法存在的问题,提出基于偏差最小原则的作用时间计算方法,并详细证明了该方法的优越性。仿真和实验结果显示,所提出的方法能够有效减小计算量和降低开关频率,同时具有较好的稳态和动态性能。

基于无源控制的车用双管升压变换器研究

新能源汽车能处于正确的电压级别下安全可靠地运行,DC/DC变换器发挥着重要作用,针对其现有控制方法多为线性控制,难以应对负载与输入电压参数多变的情况的问题;在非线性控制既无源控制的基础上引入了PI阻抗反馈补偿环路的概念,提出了一种PI阻抗补偿无源控制策略。为证明其优越性,与现有方法进行了比较。并针对负载与输入电压参数变化情况进行了模拟仿真,结果表明,该策略在输入电压跌落8 V后,仅产生了2 V的波动;负载突变为初值的一半时,仅用了不到0.01 s便重新抬升至给定电压值。由仿真结果可得,该策略不仅响应速度快、不会产生超调现象,而且在负载和输入电压发生较大变化的情况下,仍能很好的抵御外部干扰并保持输出电压的稳定性和优秀的电压纹波抑制效果,具有良好的鲁棒性。

基于双模式变频移相调制的单级式双有源桥型DC-AC变换器

针对单级式双有源桥(DAB)型DC-AC变换器关断电流较大和软开关范围有限的问题,该文提出一种双模式变频移相调制策略。首先,对DAB变换器的单移相(SPS)调制和扩展移相(EPS)调制进行时域分析,得到其功率传输特性;然后,分析变换器的关断电流与软开关条件,得到移相比和开关频率约束方程;在此基础上,分析双模式间的移相比边界条件,提出变换器运行模式的切换机制,从而在实现变换器单级功率变换的同时,保证全范围软开关并降低低压侧的关断电流;最后,通过仿真和实验验证了所提调制策略的有效性与可行性。

Analysis of Light Load Efficiency Characteristics of a Dual Active Bridge Converter Using Wide Band-Gap Devices

In this paper, the zero voltage switching (ZVS) region of a dual active bridge (DAB) converter with wide band-gap (WBG) power semiconductor device is analyzed. The ZVS region of a DAB converter varies depending on output power and voltage ratio. The DAB converters operate with hard switching at light loads, it is difficult to achieve high efficiency. Fortunately, WBG power semiconductor devices have excellent hard switching characteristics and can increase efficiency compared to silicon (Si) devices. In particular, WBG devices can achieve ZVS at low load currents due to their low parasitic output capacitance (Co,tr) characteristics. Therefore, in this paper, the ZVS operating resion is analyzed based on the characteristics of Si, silicon carbide (SiC) and gallium nitride (GaN). Power semiconductor devices. WBG devices with low Co,tr operate at ZVS at lower load currents compared to Si devices. To verify this, experiments are conducted and the results are analyzed using a 3 kW DAB converter. For Si devices, ZVS is achieved above 1.4 kW. For WBG devices, ZVS is achieved at 700 W. Due to the ZVS conditions depending on the switching device, the DAB converter using Si devices achieves a power conversion efficiency of 91% at 1.1 kW output. On the other hand, in the case of WBG devices, power conversion efficiency of more than 98% is achieved under 11 kW conditions. In conclusion, it is confirmed that the WBG device operates in ZVS at a lower load compared to the Si device, which is advantageous in increasing light load efficiency.

双有源桥无回流功率控制的死区影响与补偿

针对三重移相协同控制(CTPS)加入桥臂死区后,会导致双有源桥(DAB)变换器回流功率发生及软开关失效的问题,提出针对CTPS控制的死区补偿策略.通过分析CTPS控制不同模式下桥臂死区引起的变压器原副边电压及漏感电流的变化,基于回流功率产生的原理,更正了不同模式移相比之间的耦合关系,对功率传输模型及CTPS控制模式的切换条件进行修正,实现了死区对CTPS控制影响的有效控制.利用所提的补偿方案,抑制了由死区引起的回流功率,恢复了CTPS控制的软开关性能,具有较补偿前更优的电流应力.分别开展死区补偿前、后的实验,对死区影响的分析和所提出的补偿策略进行验证.

城轨领域综合承载的列车以太网通信网络应用

本文介绍了常用交换式以太网环网与线性网拓扑的优缺点,并以实际应用项目为依托,介绍了列车通信网络承载信号系统通信网络的方案。该方案可以承载整车的通信网络,为智慧城轨列车通信综合承载提供了一种发展方向。

一种宽带双极化波束切换微带天线的设计

以海港码头集装箱堆场的远程(无人化)操控系统为应用背景,提出一种控制方法简单和可实现性好的宽带双极化波束切换微带天线系统。该系统整体由微带阵列天线和波束控制电路两部分组成,其中微带阵列天线包含天线阵A和天线阵B两种类型。所涉及的双极化微带天线采用新型双贴片结构,使得天线实现较宽工作带宽的同时保持较高的极化隔离度;同时,通过在底层辐射贴片上开正方形环槽,实现天线的小型化。波束控制电路采用SP6T射频开关芯片,通过合理的电路设计布局,将两组射频开关集成于一块电路板,在保证低损耗、高速的多波束切换的同时减小了电路尺寸。实测结果表明:该天线的带宽达到21.8%(反射系数小于-10 dB),隔离度大于20 dB,在整个工作频段内该天线系统六个波束能够无缝覆盖-90°~90°工作区,增益优于12 dBi,双极化性能良好。