四线圈WPT系统非理想耦合及等效解耦方法

针对四线圈非理想耦合对系统输出电流特性的影响,采用等效容性耦合的方法来实现理想的四线圈系统电流输出特性。 首先结合补偿电感的磁集成,减少了无线电能传输系统磁元件数量并缩小其体积,再对等效电路参数的设计进行分析并设计了实验样机。 实验结果验证了容性耦合等效方法的准确性与有效性。 在负载范围内,样机接收端直流输出电流的波动小于8%,传输距离为75 mm时整机输出功率为300 W,效率峰值达到了81.49%。     

现代液压控制技术应用及发展

介绍了液压技术当前的发展，智能控制和新型功能材料在液压控制技术中的应用，论述了液压控制技术进一步发展的必然性，最后对液压控制技术的发展趋势进行了展望。     

LCL-S型ICPT系统输出电压特性分析与设计

针对很多无线供电应用场合需要保持输出电压恒定的需求,提出了一种高频逆变器前动态调压的恒压输出控制方法。以LCL-S型感应耦合电能传输系统为研究对象,通过阻抗分析法建模,发现通过元器件的参数配置,可使系统输入阻抗为纯阻性,减少无功分量,同时逆变器开关管实现了零电流开通与关断,但此时系统输出电压并不恒定。针对分析结果提出基于模糊自适应PI控制算法的逆变前动态调压控制的恒压输出控制方案,最后搭建了仿真实验平台和实验样机证明了分析结果的正确和控制方案的有效。     

LCL-S型无线电能传输系统负载与互感辨识方法

针对无线电能传输系统因线圈偏移、受电设备阻抗变化等导致系统模型参数不精确的问题,提出一种基于粒子群算法的LCL-S 型无线电能传输系统负载与互感辨识方法。根据LCL-S补偿拓扑原边恒流及副边恒压的输出特性,采用滤波电容能量守恒理论,建立负载输出电压与互感、原边线圈电压与负载的数学描述。以输出电压理论值与实际值之间的误差构建成本函数,设计粒子群算法,通过数值寻优实现参数的辨识。仿真与实验结果均验证了该方法能够较为准确地辨识出互感与负载大小,且无需增加额外硬件电路及控制,降低了系统复杂程度。     

压力损失可靠性计算和研究

在工程机械、矿山机械、机械加工等设备中广泛使用液压传动，而液压在动力传动中都要产生压力损失。本文就液体在油管内流动时的压力损失计算方法进行了分析和研究，提出了正确计算公式，以免在液压传动系统设计与计算时产生错误和误差，保证其计算准确与可靠性。     

Training preservice teachers to use evidence-based practices: Effects of coaching with performance feedback on teacher and child outcomes

Three-term contingency trials (TCTs) involve planned/naturally occurring antecedents, child's demonstration of target behaviors, and planned/naturally occurring consequences. Positive relationships between teachers' frequent use of TCTs and children's learning were noted in literature. This study aimed to investigate impact of an intervention package including training and coaching with performance feedback on experienced and novice special education preservice teachers' use of TCTs and relationship between teachers' implementation and child outcomes through two single-case experiments using multiple baseline across participants design. Three special education preservice teachers and three children with disabilities participated in each study. Results indicated intervention package was effective in increasing preservice teachers' use of TCTs. Preservice teachers generalized their use and sustained it during maintenance sessions conducted after intervention ended. Furthermore, as frequency and accuracy of preservice teachers' implementation increased, percentage of children's correct responses in relation to target skills improved. Implications for future practice and research are discussed.     

太阳电池最大功率点跟踪研究

提出了采用最大功率点跟踪技术提高太阳电池的输出功率．跟踪器实时调整太阳电池的输出,电压和电流,使其工作在最大功率点上．建立了最大功率跟踪的测量装置,并可直接对比有、无跟踪条件下的输出功率．本实验条件下,采用最大功率跟踪后,其平均功率增益可达10．61％．     

无线电能传输TS-S型补偿网络的建模与设计

补偿网络是无线电能传输系统中的重要组成部分,可用于提高电能传输的效率、输出功率及稳定性。在对TS-S型补偿网络建模及其参数化设计分析的基础上,采用算例验证TS-S型补偿网络模型的定频谐振、恒定电压增益和高效率特性,通过实验验证相关推论及方法。结果表明,样机电压输出稳定,在耦合系数为0.2时的效率峰值达到90%。     

液压传动与控制课程CAI课件的研究与实践

分析了液压课程教学中多媒体技术的应用现状,提出了液压CAI课件既应助教更应助学的开发应用理念,并借助多媒体软件制作了液压传动与控制课程辅助学习系统。教学实践表明,这种液压CAI模式可激发学生学习的积极性和主动性,教学质量明显提升,为其他工学课程的多媒体教学提供了借鉴。     

液力自动变速器动力传动系统的动态模型

通过对汽车液力自动变速器动力传动系统的理论分析,建立了包括发动机、变矩器、变速器、传动轴到车轮各环节的动态数学模型,通过对上述模型的分析与简化,建立了汽车动态行驶方程.     

A sensorless and simple controller for VSC based HVDC systems

Voltage source converter high-voltage direct current （VSC-HVDC） is a new power transmission technology pref- erable in small or medium power transmission. In this paper we discuss a new control system based on space vector modulation （SVM） without any voltage line sensors. Using direct power control （DPC） SVM and a new double synchronous reference frame phase-locked loop （DSRF-PLL） approach, the control system is resistant to the majority of line voltage disturbances. Also, the system response has accelerated by using a feed forward power decoupled loop. The operation of this control strategy was verified in a SIMULINK/MATLAB simulation environment. To validate this control system, a 5 kV.A prototype system was constructed. Compared to the original controllers, the current total harmonic distortion （THD）, the active and reactive deviations and the DC voltage overshoot were lowered by 2.5%, 6.2% and 8%, respectively. The rectifier power factor in the worst condition was 0.93 and the DC voltage settling time was 0.2 s.     

一种可以预设定输出电流的开关电源设计

目前,绝大多数开关电源的共性通常是具有恒压输出功能,也就是人们常说的稳压电源．然而,对一些大功率的设备,不但要求有稳定的输出电压,还要求有稳定的输出电流．同时这个稳定的输出电流值还要求能预先设定．这一种可以预设定输出电流的开关电源,在现有开关电源的基础上增加了单片机闭环控制系统,使得它可以应用在一些既需要稳定的输出电压,又需要稳定的输出电流的系统上．解决目前大部分开关电源因负载变化,造成开关电源停止工作,影响用电设备正常工作的问题．     

基于LCL型光伏并网电流谐波抑制的控制方案

新能源光伏发电并网系统中的逆变器、非线性负载以及变压器等器件产生的谐波,会影响电能质量和安全。为了抑制系统中的谐波,使输出电流很好地跟踪并网电压,实现输出电流的稳定性,提出一种带锁相环和电压反馈双电流环的LCL型光伏并网逆变器谐波抑制方法。对逆变器控制系统进行分析,建立数学模型,通过MATLAB/Simulink搭建仿真系统。仿真结果证明:该方法可以有效抑制谐波,提高电能的供电质量,满足新能源光伏并网系统对电流谐波畸变率的要求。     

微型冷热电联产系统动力装置的参数优化

建立了内燃机的通用数学模型,提出了内燃机的运行经济区.得出了改装后的LJ276M型内燃机的数学模型,并界定了此内燃机的运行经济区的边界范围,分析了此内燃机的运行优化曲线和最佳运行工况点.针对动力系统的冷热电、热电和供电3种操作模式,分别建立了能量转换数学模型,优化了动力装置的内燃机/变速箱传送比ies、电动机/变速箱传送比ims和电动机/内燃机传送比ime.结果表明：在冷热电模式下,ies和ims的优化值分别为2.9和1;在热电模式下,当动力系统需求负荷小于内燃机运行经济区的下限值时,ime取1,而当动力系统需求负荷超过内燃机运行经济区的下限值时,ime取0.85;在供电模式下,ims的最优值取2.5.     

直流稳压电源及漏电保护装置系统研制

设计了一种输入电压为5.5V～25V,输出电压为5V的直流稳压电源及其漏电保护装置系统.直流稳压电源模块采用达林顿管TIP42、OP07运算放大器及三极管构成一个深度负反馈稳压电路.输出电压经ADS1286转换为数字量后送入单片机采样输出电压,经霍尔电流传感器CSM002A、跟随器OP07后,送入ADS1286,转换为数字量后送入单片机采样负载电流.由软件程序计算功率,并在液晶上显示.通过采样负载电流与总电流的差值实现漏电检测,并进行漏电保护.经测试,系统电压调整率Su≤1％,负载调整率SL≤1％,5.5V ～ 25V输入,输出为5±0.05V.     

用于高压电子式电流互感器的能力和数据复合光纤传输系统

This paper describes a prototype power delivery system developed for high voltage electronic current transformer (ECT) that uses laser light to transfer power to and communicates with the primary converter. The design is based on optical-to-electrical power converters, solid-state diode lasers and optical fibers. Command signals are transmitted via the same up-fiber used to send power from secondary power supply to primary converter. The upward data transmission is completed during the brief interruption of power delivery without affecting steady power-supply. A simple comparator added to the primary converter can take the command data. Experimental results show that the fibers can provide reliable up-link for data transmission at 200 kb/s from the secondary to the primary converter. Based on the delivery system, the secondary converter can control three auxiliary channels to provide additional information. These monitoring channels are used in a time-multiplexing mode to provide information about the operation temperature, voltage and current at the remote unit for monitoring the ECT. This preventive maintenance or built-in test can increase reliability by giving early warning for necessary maintenance request.     

无接触电能传输系统传输效率分析

介绍了无接触电能传输系统的组成及工作原理,以高频变换器为主,对系统进行了分析。为提高逆变器的传输效率,达到降低高频开关损耗的目的,以Matlab/Simulink工具箱为基础建立了SPWM逆变器的仿真模型,并进行仿真。仿真结果显示,当PWM脉冲发生器的输出电压频率为400 Hz、载波频率为1.2 kHz时的传输效率最高。     

隔离电源系统设计

该文提出了一种输入电压22V～60V,输出电压12V、输出电流1A的电源适配器设计方案,同时可通过远程上位机控制其工作状态.该系统主要由输入部分、控制部分和输出部分组成.STC89C2051作为主控单片机,功率输出部分采用开关电源,其内部资源集成RS232通信协议,可以实现远程数据发送和接收控制命令.经过实验测试,完全达到了设计的要求.     

Direct driven wind energy conversion system based on hybrid excitation synchronous machine

A novel direct-drive type wind power generation system based on hybrid excitation synchronous machine (HESM) is introduced in this paper. The generator is connected to an uncontrollable rectifier, and a fully controlled voltage-source inverter is used to connect the system to utility grid. An intermediate DC bus exists between the rectifier and inverter. A new control strategy is proposed which achieves the maximum power point tracking (MPPT) with the control of excitation current of HESM and stabilizes the DC link voltage with the control of inverter output current simultaneously. Specially-designed buck circuit is used to control the excitation current of HESM, and grid voltage-oriented vector control strategy is employed to realize the decoupling of the inverter output power. Simulation results and experiment in 3 kW lab prototype show an excellent static and dynamic performance of the proposed system.     

变速恒频双馈风力发电机稳态运行特性仿真

基于变速恒频双馈风力发电机组,通过调节发电机转侧子电流的大小调节系统的有功功率和无功功率,实现解耦控制。并在理论推导的过程中建立数学等效模型。最后运用MATLAB／Simulink电力系统建模与仿真平台分析发电机组在无功控制模式下风电系统在稳态和三相短路故障下运行输出特性。