A 1.8 GHz Power Amplifier Class-E with Good Average Power Added Efficiency

This paper presents a 1.8 GHz class-E controlled power amplifier (PA). The proposed power amplifier is designed with two-stage architecture. The main advantage of the proposed technique for output control power is a high 37 dB output power dynamic range with good average power adding efficiency. The measurement results show that the PA achieves a high power gain of 23 dBm and power added efficiency (PAE) by 38%. The circuit was post layout simulated in a standard 0.18 μm CMOS technology.

On the Efficiency for Non-Endoreversible Stirling and Ericsson Cycles

An analysis of the Stirling and Ericsson cycles from the point of view of the finite time thermodynamics is made by assuming the existence of internal irreversibilities in an engine modeled by these cycles, and the ideal gas as working substance is considered. Expressions of efficiency in both regimes maximum power output and maximum ecological function are also shown. Appropriate variables are introduced so that the objective functions, namely power output, ecological function and efficiency can be functions of the reservoirs temperatures ratio and certain “measurable” parameters as a thermal conductance, the general constant of gases and the compression ratio of the cycle. Several results from the finite time thermodynamics literature are used, so that the developed methodology leads directly to appropriate expressions of the objective functions in order to simplify the optimization process.

Power output and efficiency optimization of endoreversible non-isothermal chemical engine via Lewis analogy

Compared with endoreversible heat engine with pure heat transfer and endoreversible isothermal chemical engine with pure mass transfer,endoreversible non-isothermal chemical engine(ENICE)is a more reasonable model of practical mass exchanger,solid device and chemo-electric systems.There exists heat and mass transfer(HMT)simultaneously between working fluid and chemical potential reservoir in ENICE.There is coupled HMT effect that in ENICE should be considered.There are two ways to consider this coupled effect.One is based on Onsager equations,and another is based on Lewis analogy.For the mathematical and physical description of the above HMT process,the model using Onsager equations are more appropriate in the linear HMT region not far from the equilibrium state,while that based on Lewis analogy is more appropriate in nonlinear HMT region far from the equilibrium state.Different from the previous research on the power optimization of ENICEs with Onsager equations,this paper optimizes power and efficiency of ENICE based on Lewis analogy.HMT processes are assumed to obey Newtonian heat transfer law(q∝ΔT,and T is temperature)and Fick's diffusive mass transfer law(g∝Δc,and c is concentration),respectively.Analytical results of power output and corresponding vector efficiency(η_(T)andη_(μ))of ENICE are obtained,which provide important parallel results with those based on Onsager equations.They include special cases for endoreversible Carnot heat engine with q∝ΔT and endoreversible isothermal chemical engine with g∝Δc.Adopting Lewis analogy in the modelling of ENICEs with simultaneous HMT is an important work.It provides important analytical and numerical results different from those with Onsager equations obtained previously and enriches the research contents of FTT.The research results in this paper have a certain guiding significance for the optimal designs of single irreversible NICEs,multistage NICE systems,practical mass exchangers,solid devices,chemo-electric systems,and so on.

Design and Analysis of a Power Efficient Linearly Tunable Cross-Coupled Transconductor Having Separate Bias Control

A common current source, generally used to bias cross-coupled differential amplifiers in a transconductor, controls third harmonic distortion (HD3) poorly. Separate current sources are shown to provide better control on HD3) . In this paper, a detailed design and analysis is presented for a transconductor made using this biasing technique. The transconductor, in addition, is made to offer high Gm, low power dissipation and is designed for linearly tunable Gm with current mode load as one of the applications. The circuit exhibits HD3) of less than –43.7 dB, high current efficiency of 1.18 V-1 and Gm of 390 μS at 1 VGp-p @ 50 MHz. UMC 0.18 μm CMOS process technology is used for simulation at supply voltage of 1.8 V.

计及氢能高效利用和热电灵活输出的综合能源系统源荷灵活运行策略

为进一步发挥氢能高效利用优势,构建绿色低碳能源系统,提出一种计及氢能高效利用和热电联产灵活输出的综合能源系统源荷灵活运行策略。首先,对源侧供能模型进行两方面改进:一是引入含风电制氢、燃气混氢、多能用氢和储氢的氢能利用模型,并考虑到电解水和甲烷化反应过程中的热量散失情况,引入热量回收装置,构建计及热量回收的氢能高效利用模型;二是针对常规热电联产灵活性不足的问题,构建含电锅炉和有机朗肯循环的热电灵活输出模型,以解耦常规热电联产“以热定电”和“以电定热”限制。其次,在荷侧引入含可转移、可削减和可平移的电、热柔性负荷,以缓解电、热负荷峰谷差,并与源侧相结合,形成源荷灵活运行模型。最后,综合考虑阶梯型碳交易成本、设备运行维护成本、弃风成本以及购能成本,建立综合能源系统源荷灵活优化运行模型。采用CPLEX求解器对所提综合能源系统源荷灵活运行模型进行求解,并设置不同场景进行对比。结果表明,相比常规氢能利用模型,考虑所提计及热量回收的氢能高效利用模型时,系统的总成本、碳排放量分别降低了1.92%、4.22%,并且引入热电联产改进模型后,其总成本、碳排放量可进一步降低4.08%、7.32%,实现系统低碳、经济和灵活运行。

无线电能传输系统最大效率追踪及恒压输出复合控制方法

针对无线电能传输(WPT)系统的传输效率受耦合线圈之间的互感以及负载影响的特点,该文提出一种基于阻抗匹配技术的最大效率追踪及基于前馈PI控制的恒压输出复合控制方法。首先,对双边LCC型WPT系统的参数和传输效率进行分析,通过调整系统参数优化系统的传输效率。其次,在二次侧使用DC-DC变换器采用阻抗匹配的方法实现最大效率追踪,同时在一次侧采用DC-DC变换器利用前馈PI控制器闭环控制负载端电压实现恒压输出。该方法中,效率追踪和电压控制之间相互独立,互不干扰。此外,该方法还通过系统工作时的电路参数来估算线圈间的互感值,并通过线性拟合的方法对该估算互感值进行修正,得到更精确的互感估算值。最后,通过搭建实验平台验证了该方法的可行性和有效性。与PI控制相比,前馈PI控制方法在快速性和抗扰动性上均具有明显优势。

基于SWIPT的无小区大规模MIMO-NOMA系统能量效率研究

无小区大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)与非正交多址接入(Non-Orthogonal Multiple Access,NOMA)都是未来6G的使能技术。无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)技术在进行信息解码的同时收集能量,与无小区大规模MIMO-NOMA优势互补。文中基于SWIPT研究无小区大规模MIMO-NOMA系统中的能量效率问题,通过联合优化功率分配系数和SWIPT的时隙切换(Time Switching,TS)系数,提高系统的能量效率。为了最大化能量效率,采用布谷鸟算法设计功率分配系数。考虑一种特殊情况,将所有终端的TS系数设置相同,进而推导了最佳TS系数的封闭表达式。仿真结果表明,相较于几种已有方案,文中提出的优化方案可以显著提升系统的能量效率。

感应电能传输系统多并联拾取模块电流和输出功率均衡方法

大功率感应电能传输系统通常采用多并联拾取模块结构。然而,多并联拾取模块参数不一致,会导致各个拾取模块的电流和输出功率不均衡,从而降低系统效率,严重时会因模块过流而造成系统故障。为解决该问题,文中提出一种基于并联拾取模块补偿电容器的多并联拾取模块电流和输出功率均衡方法。首先,介绍了传统感应电能传输系统与所提出的感应电能传输系统拓扑的特性。然后,分别分析了互感、拾取线圈自感及内阻对电流分布和系统效率的影响。最后,通过4个并联拾取模块的感应电能传输系统实验平台验证了所提方法的有效性。实验结果表明,采用所提方法时多并联拾取模块的电流和输出功率基本一致,并且相比传统感应电能传输系统,系统效率最高提升了2.21%。

质子交换膜燃料电池性能优化控制

质子交换膜燃料电池(proton exchange membrane fuel cell,PEMFC)的热管理,是影响PEMFC安全、稳定、高效运行的核心关键因素。该文在分析PEMFC热管理子系统的结构,以及关键组成部件(包括空气压缩机、冷却液循环泵和冷却风扇)的工作原理基础上,首先搭建耦合热管理子系统的PEMFC非线性仿真模型,进一步将其简化处理得到用于控制的线性模型;在此基础上,设计基于卡尔曼滤波的状态观测器,以实现对状态和不可测量扰动的估计,从而消除模型稳态误差;随后设计目标计算器,以净输出功率跟踪误差最小化和系统效率最大化为目标,对PEMFC系统工作状态进行优化;进而基于线性控制模型,设计无偏显式模型预测控制(offset-free explicit model predictive control,offset-free EMPC),对优化工作状态进行跟踪控制;最后,搭建一个软件在环(softwareintheloop,Si L)测试平台,通过与传统MPC控制策略的仿真结果对比可得,无偏EMPC控制策略可以显著将净输出功率的平均跟踪误差绝对值从344.29W减小到82.19W,系统效率从40.32%提升到46.56%,算法平均单步计算耗时从26ms降低到11.8ms,并且可以约束PEMFC系统运行在稳定和安全的工况。

空间高温区自由活塞斯特林发电机工作特性试验研究

测试了不同冷端温度下,外负载、运行压力和加热功率对高温区自由活塞斯特林发电机的热端温度、电电效率、输出功率、频率的影响。研究结果表明,在同一冷端温度时,加热功率的增加使发电机的电电效率、输出功率、热端温度上升,而外负载、运行压力的增加则起相反作用;发电机的频率与外负载呈负相关变化,与运行压力、加热功率呈正相关变化。提升冷端温度使发电机的输出功率、电电效率和频率下降,热端温度上升。在三种不同冷端温度下,外负载、加热功率和运行压力对发电机输出特性的影响规律不变。经过测试,发电机在运行温区为495~1058 K时,最大输出功率103.681 W,电电效率20.5%。

地热能有机朗肯循环系统设计与动态仿真

针对地热能利用,根据地热井口条件通过热力学计算和设备选型设计了对应的ORC机组,并对该机组动态特性进行了仿真;研究了热源温度和流量、冷却水温度以及工质流量4种参数变化对ORC机组关键运行参数和性能的影响规律。结果表明:机组输出性能对冷却水温度变化最为敏感,冷热源温度增大10℃,轴功分别减小16%和增大7%;热源温度和流量增大都会使过热度、蒸发压力和轴功显著升高,热效率略有下降,但其对机组冷端传热的影响有限,对热端传热的影响很小,过热度和蒸发压力几乎不变;相比冷热源参数的变化,工质流量变化时机组关键参数的波动最小,机组能很快恢复稳定。

D类音频功放的双声道转单声道电路设计

本文设计了一种适用于D类音频功放的双声道转单声道电路,可有效将立体声放大器转换为单声放大器。该电路有效降低了功放的输出阻抗,减小了输出功率管的耗散功率,提升了效率;同时,因其并行工作的原理,单声道模式的总承载电流增大,相同总谐波失真下单声道模式的最大输出功率得到提升。

定日镜场在额定输出功率条件下的光学效率优化

为推动“双碳”目标实现,以光线追迹为核心,建立了定日镜平均输出热功率优化模型.首先,确定输出热功率是关于光学效率等参数的函数,通过给出阴影遮挡效率、集热器截断效率等参数的计算方法,提出了定日镜场输出热功率的计算方案.其次,提出定日镜场输出热功率的优化方案.针对定日镜规格相同的情况,提出“吸收塔选址策略”约束吸收塔的位置,提出“分区域同心圆规划策略”完成定日镜的排布,建立了定日镜输出热功率优化模型,并采用变步长搜索法完成最佳参数的求解.最后,针对定日镜规格不同的情况,提出“定日镜规格分区域规划策略”,并结合二分法和变步长搜索法完成最佳参数的求解.

PT对称多线圈并联无线电能传输系统参数优化

针对宇称时间(parity-time,PT)对称多线圈并联无线电能传输(wireless power transfer,WPT)系统参数相互关联,系统参数配置困难,提出一种基于PT对称的多线圈并联WPT系统参数优化设计方法。建立基于PT对称多线圈并联WPT系统数学模型,给出系统输出功率、传输效率以及有效传输距离的一般性影响规律表达式。采用一种非线性规划和遗传算法相结合的优化方法,以输出功率为目标函数,以传输效率和有效传输距离为约束条件,对系统发射-接受线圈数及谐振参数进行寻优。根据优化结果搭建实验样机,实验结果表明系统在满足所需传输效率及有效传输距离下,系统功率输出达到设计要求,验证了理论分析和优化方法的有效性。

Thermodynamic performance of Dual-Miller cycle(DMC) with polytropic processes based on power output, thermal efficiency and ecological function

This study reports a new model of an air standard Dual-Miller cycle(DMC) with two polytropic processes and heat transfer loss.The two reversible adiabatic processes which could not be realized in practice are replaced with two polytropic processes in order to more accurately reflect the practical working performance. The heat transfer loss is taken into account. The expressions of power output, thermal efficiency, entropy generation rate(EGR) and ecological function are addressed using finite-time thermodynamic theory. Through numerical calculations, the influences of compression ratio, cut-off ratio and polytropic exponent on the performance are thermodynamically analyzed. The model can be simplified to other cycle models under specific conditions, which means the results have an certain universality and may be helpful in the design of practical heat engines. It is shown that the entropy generation minimization does not always lead to the best system performance.

Efficiency and Output Power Evaluation of a Wavelength Converter Based on FWM in a Single Mode Fiber

A frequency domain analysis is presented to determine the performance characteristics of a tunable all-optical wavelength converter using four-wave mixing (FWM) in a single mode fiber (SMF) around the zero dispersion wavelength using two pump lasers. The output converted signal power as well as efficiency evaluated at a bit rate of 10 Gb/s show that the signal power is substantially higher at lower values of wavelength separation.

基于热流固耦合的增强型地热有机朗肯循环发电系统性能分析

本文建立了耦合井筒、热储、有机朗肯循环发电系统的详细数学模型,包括三维非稳态热流固耦合模型和有机朗肯循环发电系统热动力学模型,参考青海省共和县恰卜恰干热岩体地热地质特征,包括压裂储层、围岩、裂隙、井筒等特征参数,研究了注入流量、注入温度和井间距对系统净输出功、年均净输出功和热效率的影响规律。结果表明:在一定的注入流量、注入温度和净间距下,随着时间的推移,岩石孔隙压力和热应力作用使得裂隙渗透率增大,注入泵功耗是降低的,净输出功和热效率也是降低的。注入流量的增大提高了膨胀机轴功、注入泵功耗和生产温度衰减速率,进而导致热效率降低,存在最优的注入流量50 kg/s,使得年均净输出功达到最大值1470.1 kW。注入温度的增大可以提高系统热效率,降低净输出功的年均衰减速率,当注入温度为60℃时,年均净输出功最大。井间距的增大减缓了生产温度的衰减速率,有利于热效率的提高,但是也同时也增大了膨胀机轴功和注入泵功耗。当分支井间距为450 m时,年均净输出功达到最大值1497.3 kW。此研究可为增强地热发电系统的开发利用提供指导。

5G基站能效评估影响因素分析及分级体系初探

伴随着全社会数字化转型,5G网络作为重要的数字基础设施,能耗与碳排放快速增长,将成为通信行业在2030年前实现碳达峰的关键因素。通过5G基站能耗和能效洞察,提出5G基站设备能效评估方法与模型,首次完成了影响5G无线网设备能效的关键要素分析,并初步搭建5G基站设备能效分级体系和标准,可有效牵引5G无线网络持续朝着绿色低碳可持续发展。

磁耦合谐振式无线电能传输系统功效失步优化

针对磁耦合谐振式(magnetic coupling resonant,MCR)无线电能传输(wireless power transmission,WPT)系统输出功率与传输效率数量级不匹配以及功效同步优化策略需特征融合Pareto最优解的问题,提出功率效率特征缩放的熵值法,以此对Pareto解集特征融合求权重,得到失步状态下的改进功效同步优化目标函数,实现输出功率与传输效率的同步提升。首先,通过确定影响双线圈MCRWPT系统输出功率和传输效率Pareto最优解的参数,采用所提出的熵值法对差分进化算法(differential evolution,DE)的目标函数进行改进。然后,基于功效工作特性和DE算法对改进的失步条件下的系统功效模型优化,模拟输出功率和传输效率随参数的变化。从仿真结果可知,双线圈MCRWPT系统的输出功率和传输效率同时都得到了提高。最后,通过实物系统搭建验证改进失步功效模型方法的有效性。

膨胀比对活塞式膨胀机工作特性影响的研究

活塞式膨胀机在压缩空气储能领域具有广泛的应用,但是效率低,很大程度上限制了其发展。为改善活塞式膨胀机的工作性能,通过MATLAB建立活塞式膨胀机的仿真模型,通过实验方法验证仿真模型的准确性,以输出功率和效率作为性能指标对活塞式膨胀机进行研究,分析了进气压力、间隙容积、进气持续角对膨胀机输出特性的影响。结果表明:在恒定工况下,随着进气压力的增大,膨胀机的输出功率增大,但效率降低;在稳定的进气压力下,膨胀机存在最优间隙容积与进气持续角;活塞式膨胀机的效率随进气持续角的增大而降低,进气持续角越大膨胀机输出功率随转速的升高下降斜率增大;3 MPa的进气压力下,膨胀比为2.18时膨胀机的效率最佳,进气持续角为90°时膨胀机输出功率最优,在转速为570 r/min时输出功率达最大4.29 kW、效率达到19.6%。为可变膨胀比活塞式膨胀机的设计提供了理论依据。