查询词典 supply frequency

A low minimum operating supply voltage of 2.9V, and a low shutdown quiescent current of less than 1μA, make the LT3757 ideally suited for battery-operated systems.The LT3757 features soft-start and frequency foldback functions to limit inductor current during start-up and output short-circuit.The device is available in a small 10-lead DFN (3mmx 3mm) or MSOP package.

本文介绍了LT3757主要特性，方框图以及典型应用电路，包括高效升压转换器， 3.3V输入，5V/10A输出升压转换器， 8-16V输入24V/2A输出升压转换器，高压反激电源电路，以及5.5V-36V输入，12V/2A输出SEPIC转换器和非绝缘的反相SLIC电源。

Based on surveying the development of variable frequency power supply and analyzing its development tendency, and considering the practical features of the assignment, the conversion system is designed as follows: it selects the 3-phase Pulse Width Modulation Engine SA4828 as the PWM control signals generator; it chooses the single-chip-computer PIC16F877 as the microcontroller, which integrated the A/D modulation, which cuts down the complexity of the hardware system and strengthens the dependability of the system.

在论述和分析了变频电源及其控制技术发展的概况和趋势的基础上，结合本课题任务的实际要求，设计了一套中小功率的逆变电源。系统中PWM控制信号采用专用集成芯片SA4828生成，减轻了控制器的工作量也提高了系统的可靠性。控制器选用集成了A/D转换器的单片机，使得系统的硬件复杂性降低，提高了可靠性。

The foundation of this system provides a good reference to promote the standardization and intelligence of the overhaul and maintenance of vacuum switches. This paper develops a special HF pulse power supply for internal pressure estimation, which achieves the output of HF-HV sinusoidal pulse wave whose frequency and amplitude can be modified respectively, and meets the design requirements according to the results of Simulink simulation and practical experiments. With the help of AT89S52, this paper designs an I~2C serial bus based signal detection system for peak value signal acquisition of HF pulse currents, which communicates with the upper computer by asynchronous serial communication for uploading the data. In the upper computer, a human computer interface is developed by Matlab software, whose functions are to do some computation and graphic display, such as calibrating the relation curve of vacuum degree and peak value of HF pulse currents, vacuum degree computation, and vacuum lifetime evaluation analysis basing on grey forecasting model as well as making relative suggestions.

本文研制了用于真空度检测的高频脉冲电源，通过Simulink仿真和试验检验其满足设计要求，实现了电压幅值和频率独立可调的正弦波高频高压脉冲输出；利用以AT89S52为核心基于I~2C串行总线的信号检测系统实现高频脉冲电流峰值信号的采集，通过异步串行通信实现单片机与计算机之间的数据通信，将检测数据传至上位机；在上位机利用Matlab开发人机交互界面，实现相关数据处理和图形显示，包括真空度——高频脉冲电流峰值关系曲线标定、真空度数值计算、基于灰色预测模型的真空寿命评估分析和提出相应决策建议。

Taking the administrative villages as units, a comprehensive and detailed survey was made to attain the rich and reliable data, including the information about the status of the land use, the relationship of the land supply and demand, the living standards of farmers and the minimum of urban resident living guarantee and so on. Then the estimating system was established. Afterwards, basing the survey and the system, the character of each unit was transfer into data. And, utilizing the frequency law, the whole county was divided into four expropriation land blocks. The area was measured and the map, showing the differences between blocks, of the Arable Land Blocks for expropriation of Siyang was protracted by the method of GIS. Finally, the land expropriation price is calculated by agricultural land economical function compensate method and urban construction land criterion price avulse method, then the price was tested by expropriation case comparison method. It is beneficial not only for protecting farmers rights and interests, but also for link up with the current land compensate standard, so this way to calculate the land expropriate price is more reasonably.

以行政村为基本单元，对该地区的农用地利用现状、土地供求关系、农民生活水平扣城镇居民最低生活保障水平等情况进行了调查，建立征地区片价格评价体系，根据每个评价单元的综合评价分值，运用总分频率法将全县分为四个区片，并对各级区片进行面积量算，借助地理信息技术绘制了《泗阳县农用地征地区片价格分布图》，显化了农用地征地区片价格的空间分布及其差异，最后运用农用地经济功能价格补偿法和城镇建设用地基准地价剥离法综合测算农用地征地区片价格，并用征地案例比较法的测算结果加以比较验证，证明此测算结果相对更加科学合理，既有利于保障被征地农民的合法权益，又有利于与现行的征地补偿标准相衔接。

A new kind of constant pressure water-supply system composed of a single-chip computer and frequency changer is introduced.

介绍了一种用变频器和单片机组成的恒压供水系统的设计方案，给出了控制器的硬件结构及控制原理框图。

Was established in January 2004 to produce the development of SMD transformers, switching power supply transformers, driver transformers, matching transformers, small transformers, low frequency transformer, power filter, choke coil inductor, linear inductor coil , air core coils, such as various types of transformers and coils of professional manufacturers.

显龙电子有限公司成立于二零零四年一月，以生产开发 SMD 变压器、开关电源变压器、驱动变压器、匹配变压器、小型变压器、低频变压器、电源滤波器、扼流电感线圈、线型电感线圈、空芯线圈等各类型变压器及线圈的专业厂家。

Demonstrates composition and function of a constant pressure water-supply system controlled by PLC and frequency converter as well as the design of each function module.

阐述了基于PLC和变频器控制的恒压供水系统的组成、功能及各功能模块的设计方法。

The results show that the frequency and phase position of frequency converter output power are out of phase with that of supply power, which is the main reason leading to metering system breakdown.

分析结果认为：变频器输出电源的频率和相位与供电电源频率和相位不同步是造成计量系统产生故障的主要原因。

Particularly paragraph 5 generation products WXG-frequency conversion governor without pressure (non-smoking Cheng) pressurized water pipe network equipment to be built pools, water tanks, passed 50%-90% without extensive phenomenon, saving investment, no two pollution, fully automatic operation, continuous water supply, and many other advantages, and create a water supply equipment direct contact in the water pipe precedent and surrounded by five ministries to the Ministry of Science and Technology, 2000 national focus of new products.

特别是第5代产品WXG型变频调速无负压管网增压供水设备，以不用建水池、水箱，节电50%-90%，无跑冒滴漏现象，节省投资，无二次污染，全自动运行，停电不停水等诸多优点，开创了供水设备可直接串联在自来水管道上的先例，并被科技部等5部委授予2000年度国家级重点新产品。

The main products have Analog Oscilloscopes, DC power supply, variable frequency power supply, electronic load.

主要产品有模拟示波器、直流电源、变频电源、电子负载。

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％。