功率损耗

For the ill conditioned load flow caused by the error produced in the transformation from electricity quantities to average power, direct current load flow and sensitivity vector are presented to find out the ill node, then by adjusting the load curve and generation curve in a certain principle, which is shown in detail with several flow charts, a new operation mode is reestablished to ensure the convergence of the calculation. Optimal multiplier method is proposed to work out the least square solution according to ill conditioned structural power network. The electricity quantities flow method enhances the reliability and accuracy of the calculation of the power transmission losses.

该方法可根据当前输电网中各个变电站24小时的电量记录，利用电量潮流计算对输电网总线损和各条线路损耗进行计算，使计算的精度满足降损措施分析和指标考核的要求；并且对于由负荷出力曲线转化成平均功率计算潮流时引入的误差，进而导致潮流计算不收敛的情况，采用直流潮流法，依据相角对有功功率的灵敏度向量判断出"网络异常点"，并且给出了解决此种情况的方法流程图；针对结构病态的电力系统潮流计算不收敛的情况，运用非线性约束优化方法中的最优乘子法求解潮流方程的最小二乘解，从而解决了电量潮流法计算理论线损时的收敛性问题，增强了该方法的适用性。

The input power flow into the system, the loss one of the system and the transfer one between the two oscillators were studied.

通过改变耦合阻尼的大小，分析了系统输入功率、系统内损耗和模态间传递功率流的变化规律。

Switching power amplifier of magnetic bearing worked in hard switching. To overcome drawbacks of large loss of switching and current harmonic distortion, a parallel resonant DC link soft-switching power amplifier was adopted in this paper.

为克服磁悬浮轴承开关功率放大器工作在硬开关状态时存在的开关损耗和电流纹波干扰严重的缺点，提出一种磁悬浮轴承并联谐振直流环节的软开关功率放大器电路。

Then the MEMS solenoid type electromagnetic actuating and novel, frictionless and wear-free, and simple structure are designed for fiber-deflecting type MEMS VOA: One of the two coupled single mode fibers is completely fastened in one of the three aligned U-shaped grooves while the deflectable fiber is partially fixed in another groove with a long front section suspending over the wider groove as a cantilever beam. The two fibers, any one for input and the other for output, are well aligned initially so that the insertion loss is very low. Beside the deflectable fiber is a solenoid microactuator with a U-shaped permalloy core attracting a permalloy piece glued on side of the fiber cantilever so that the fiber is deflected and the optical power coupled between the fibers decreased continuously. Using MEMS solenoid as a continuous actuator and the novel structure of VOA are not seen in literature.

为光纤偏移型MEMS可变光衰减器设计了MEMS螺线管电磁驱动方式以及新颖的避免了静摩擦、磨损而且简单的整体结构形式：在硅基片的三段V形槽结构中，将两个对接单模光纤之一完全固定在基片上，只将另一根光纤的稍后部位固定于基片上而使其前端的一定长度悬空，形成一个悬臂梁结构；初始对准后两根光纤之间的光传输损耗很小；通过U型铁芯MEMS螺线管吸引固定于光纤悬臂梁上的坡莫合金片，驱动光纤悬臂梁连续偏移以使两根光纤之间功率传输系数连续变化，从而达到光功率连续衰减的目的。

Compared with hard-switching inverter, the soft-switching inverter's power swatches turn-on at zero voltage or zero current conditions, zero switching losses in theory, which can improve the efficiency of the system and device power density, reducing the system electromagnetic interference and ensure a brushless DC motor performance and reliability.

与硬开关逆变器相比软开关逆变器的功率开关在零电压或零电流条件下导通，理论上开关损耗为零，从而可以提高系统的效率和装置的功率密度，减小系统的电磁干扰，保证了无刷直流电机的性能和可靠性。

Optical time-domain reflectometry located the regions where optical attenuation occurred due to leakage; optical power meter acquired the transmitted power at the end of fiber, and these events could be identified according to the characteristics of signals.

在光入射端，用光时域反射计对上述事件引发的损耗进行定位；在光输出端，用光功率计检测光功率的变化，并根据信号特徵来判定事件的类型。

Based on two kinds of control strategies of VSR under unbalanced grid condition,the introduction of a new VSR control strategy featuring undamped -oscillation that simplifies the controller structure and effectively improves VSR"s performance under unbalanced grid condition.· A systematic description of the state switching in trilogic PWM signal generation of three-phase CSR by using the conversion between bilogic and trilogic switching functions.· Referenced to the CSR"s trilogic PWM signal generation, an approach to achieve low-stress natural commutation of switching devices by reshuffling the vector composition sequence, resulting reduced switching loss.

在研究了两类电网不平衡时的VSR控制策略基础上，提出了一种新型的基于无阻尼振荡控制器的VSR不平衡控制策略，在简化控制结构的同时，有效地改善了电网不平衡时的VSR控制性能；·通过二、三值逻辑开关函数间的转换，系统地描述了三相CSR三值逻辑PWM信号发生中的状态切换；·结合三相CSR三值逻辑PWM信号发生规律，提出了通过调整矢量合成顺序而使功率管获得自然换相的低电压应力SVPWM控制，从而有效地降低了功率管的开关损耗。

Referenced to the CSR's trilogic PWM signal generation, an approach to achieve lowstress natural commutation of switching devices by reshuffling the vector composition sequence, resulting reduced switching loss. With the background of and well instanced by the Xinjiang Autonomous Region's Key SciTech Project"Solar Photovoltaic grid-connected inverter", the dissertation work implemented the new approach of a grid-connected PV inverter that was of single-phase VSR topology and with MPPT .

在研究了两类电网不平衡时的VSR控制策略基础上，提出了一种新型的基于无阻尼振荡控制器的VSR不平衡控制策略，在简化控制结构的同时，有效地改善了电网不平衡时的VSR控制性能；通过二、三值逻辑开关函数间的转换，系统地描述了三相CSR三值逻辑PWM信号发生中的状态切换；结合三相CSR三值逻辑PWM信号发生规律，提出了通过调整矢量合成顺序而使功率管获得自然换相的低电压应力SVPWM控制，从而有效地降低了功率管的开关损耗。

In order to obtain more exact analytical solution to study the output characteristics of double-clad fiber lasers,according to the continuous-wave rate equations of fiber lasers,using typical parameters of double-clad fiber lasers,the contribution of the re-emission effect arising from the interaction between the upper-level atoms and pump light was estimated.Taking into account the predominant part of the re-emission to improve the accuracy of the integration approximated rate equations,the integration of the product of the loss and radiation should be found and explicit analytical expressions for the output of the DCFLs and gradient efficiency of the pump radiation,were deduced,and certain issues of concern were discussed.

为了求得用于研究双包层光纤激光器输出特性的更为精确的解析解，根据稳态速率方程组，针对典型的双包层光纤激光器参量，在估计了上能级粒子再发射项和抽运光产生的影响后，采用保留再发射贡献主导部分的办法以提高可积分近似方程的精确度，明确地提出了要获得光纤激光器输出功率的解析表达式的关键在于求出损耗系数与光场乘积的积分值，简洁地求得了输出功率和抽运光斜线效率的显函数解析表达式，并对其相关问题进行了讨论，以915nm，920nm和975nm的抽运光为例，当输出激光为1090nm时，得出975nm抽运光产生的斜率效率最高并可高达约87%。

According to the problems above, this paper analyzes how to design current filter under the situation of Linear Second-Side Power System and SSPS; how to use Amorphous Cores in the design of HVIT and the advantages it brings; why "series-wound problem" happens and the relationship with SSPS switching frequency; how to improve power losses of LSPS and how to use PCB for the thermal design of SSPS.

论文针对以上四个问题，详细分析在恒功率型线性以及开关二次侧情况下电流滤波网络的设计；功率等级提升情况下，非晶材料在高频高隔离变压器中的应用及优势；&串扰&问题的原因以及二次侧工作频率的影响；线性二次侧的损耗改善方法以及开关二次侧利用PCB散热的实现。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失