无应力的

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。

This welding wire not only has the inherent properties of metal powder-cored wire, such as with better welding quality, without slag, highly efficiency and conveniently adjusting the alloying elements etc., but also has the advantage of low hardness in as-welded (less than HRC45), good machinability, high hardness in as-aged (more than HRC55) and better wear resistance with customary working procedure on making or repairing equipments such as rollers when reasonable designing the alloys content. The author adequately makes use of the high-tempering in the required stress relieving working procedure. During this working procedure, which causes the hardness of overlaying metal increased by the reason of austenite changes into tempered martensite and more chiefly what is the precipitation of a lot of carbide by secondary hardening simultaneously. This wire can solve the hard rolled problems of some solid wires with higher alloys while it can get over the conflict of existing overlaying materials what are always possesed high hardness with poor machinability or low hardness, good machinability with poor wear resistance. Further, it also can overcome the intenerating phenomena between welding beads and make the external hardness of overlaying metal uniform. Be sure it could be found important meaning in the overlaying of wear-resistant equipments, such as the precise roller.

该焊丝除了具有金属粉型药芯焊丝焊接质量好、无渣、高效率和合金成分可方便调节等固有的优点外，合理的设计粉芯中的合金成分，按通常工序制造与修复轧辊等设备，充分利用必需的消除应力工序的高温回火，堆焊层金属在奥氏体转变为回火马氏体的同时更主要是通过二次硬化析出了大量碳化物导致硬度增加，使得该焊丝还具有焊态硬度低(小于HRC45)、机加工性能好和时效态硬度高(大于HRC55)、耐磨性能好等优点，解决了某些高合金实芯焊丝轧制困难的问题，同时克服了现行堆焊材料硬度高、加工性能差或者硬度低、加工性能好、耐磨性差的矛盾，并能克服焊道之间的软化现象，使堆焊表面硬度较为均匀，对耐磨件，譬如精轧辊的堆焊具有重要意义。

At first, I collect and analyze the relative dates, and statistics fault models. Then I finish the analysis from three aspects, instruction of circuit, stress of surrounding, and tolerance, thus providing basis of design. The following designs are in progress from four aspects, which are circuit design, thermal design, derating using and screening. At last, I make the update generator in batch process, and collect and analyze reliability dates again. I proved that the life of the improved HF electrodless light is over to 60,000 hours.

首先进行了与可靠性相关的数据收集与分析，对故障模式进行统计；然后从电路结构、环境应力及容差三个方面进行可靠性分析，从而为关键的可靠性设计提供了依据；接下来的可靠性设计，从电路设计、热设计、降额使用、筛选四个方面逐一解决了可靠性分析阶段发现的问题；最后，我将改良的发生器批量生产，并从中重新收集了可靠性数据进行计算，事实证明改良后高频无极灯的平均寿命已达到6万小时。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。