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什么是IQ Option以及它如何工作?

图2显示了相应的增益和相位图。

What is Non-Inventory Item?

Non-Inventory Item – is a type of product that is purchased or sold but whose quantity is not tracked. This type of items are purchased for company use or custom product 什么是IQ Option以及它如何工作? purchased for Projects.

Non-Inventory Items appear 什么是IQ Option以及它如何工作? in sales process (on Sales Quotes, Sales Orders, Sales Invoices, or customer Credit Notes). If you select “Is purchased from supplier” check box on the, non-inventory items appear in the supplier process (on Purchase Orders, Purchase Invoices, or supplier Credit Notes).

Use Non-Inventory Items to track merchandise that:

    什么是IQ Option以及它如何工作?
  • You sell but do not purchase.
  • You purchase but do not resell.
  • You purchase and resell but 什么是IQ Option以及它如何工作? do not track as inventory.

What’s the difference between Inventory and Non-Inventory Items?

Inventory Items are items that you buy and then stock for a while before selling. Kpi.com Accounts 什么是IQ Option以及它如何工作? tracks the quantity on hand, the current stock value (transaction value), and the FIFO method to calculate stock valuation. It also tracks some accounting information like “cost of goods sold” for inventory items that you have sold.

Non-inventory items are items that you purchase (usually on behalf of a specific customer) and then immediately sell or install, 什么是IQ Option以及它如何工作? or items that you sell without ever buying. For non-inventory items, kpi.什么是IQ Option以及它如何工作? com Accounts will only track how much you have spent or taken in. Some people use non-inventory items even for items that they stock because they prefer a simpler approach—even though it gives them less information

On-Premises

On-premises is the software and technology that is located within the physical confines of an enterprise often in the company’s data center as opposed to running remotely on hosted servers or in the cloud.

By installing and running software on hardware located within the premises of the company, internet technology (IT) staff has physical access to the data and can directly control the configuration, management and security of the computing infrastructure and data.

On-Premises vs. SaaS and Cloud Solutions

Also referred to as “on-prem” or 什么是IQ Option以及它如何工作? on-premise, on-premises software is the more traditional method for working with enterprise software, and typically requires a software license for each server and/or end user that will be working with the software.

On the other end of the spectrum are hosted services for managing data and public cloud solutions, where third parties are responsible for managing and 什么是IQ Option以及它如何工作? securing the infrastructure that houses the data stored on their servers.

These 什么是IQ Option以及它如何工作? software-as-a-service (SaaS) and cloud computing alternatives to on-premises software are frequently considered for their potential cost savings that result from reduced expenses related to staffing, power consumption, maintenance and security.

Hybrid Solutions

A third option that has become more 什么是IQ Option以及它如何工作? popular in recent years are hybrid 什么是IQ Option以及它如何工作? solutions like Microsoft s Azure Stack that enable enterprises to run some 什么是IQ Option以及它如何工作? workloads and applications on-premises while utilizing the cloud for other workloads.

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2. For the Retail Data Analysis Exercise (dataset distributed in the last class) , generate a report which consists of tables and graphs. Think about insights that you can generate from this data. For example, which product categories are seeing 什么是IQ Option以及它如何工作? a consistent decline in sales. Your submission should contain your R code and a power point presentation. The presentation should be formal, in that, it 什么是IQ Option以及它如何工作? should look like something that you 什么是IQ Option以及它如何工作? would present to your CXO team 什么是IQ Option以及它如何工作? or important clients. Your report should also contain insights about the following.

前馈电容的作用-DCDC

VirtuousLiu 于 2019-04-20 21:59:14 发布 14831 收藏 227

DCDC电路中的前馈电容

DCDC电路

如下图为典型的DCDC电路:芯片是台湾省立琦科技的。

上图为DCDC典型应用电路,CIN为输入滤波电容,CBOOT是上管驱动“自举”电容,L是储能电感,R1和R2是反馈电阻,CFF是前馈电容,COUT是输出滤波电容,RT是内部运放补偿器件。

有前馈电容和没有前馈电容

没有前馈电容

在这里插入图片描述

如果没有前馈电容,内部补偿DC-DC转换器的反馈网络由两个反馈电阻组成,用于设置转换器的输出电压,如图1所示。

输出电压公式为:Vout=Vfb*(1+R1/R2)

在这里插入图片描述

图2显示了相应的增益和相位图。

有前馈电容

在这里插入图片描述

图3显示了在反馈网络中添加了前馈电容C1(Cff)。

输出电压公式为:Vout=Vfb*(1+R1/R2)。

但是因为有前馈电容,增益和相位已经受到影响,图4显示了相应的增益和相位图。

因为加入了前馈电容,所以与反馈电阻形成新的零点和极点,虽然Cff在其零点频率之后引入了增益提升,但是环路相位变化(提升)在零点频率和极点频率之间达到最大值; 请参见以下等式1和等式2的计算。
(1)RI和CFF形成了一个零点

在这里插入图片描述

(2)RI、R2和CFF形成了一个极点

零点和极点的位置如Figure 4所示。(在上面)

前馈电容的作用

增加了前馈电容设计, 变换器可以更有效地响应输出电压上的高频干扰(交流阻抗小)。
图2和图4中的 bode 图显示, 每个反馈网络在较低频率下的响应是相同的。在中到高频率下, 随着通过 C1(CFF) 的阻抗路径的减小, 输出电压到反馈端的扰动(变化)衰减较小, 并有效地提供增益和相位的提升。

在DCDC工作电源中, 增加的增益和相位与会使得转换器对负载瞬态响应速度更快, 因为在反馈节点检测到的电压偏差在较高频率下衰减较少。转换器的反应是调整占空比, 以更快地纠正输出电压偏差。

为了优化瞬态响应, 选择合适的Cff 值, 这样环路反馈的增益和相位提升将增加转换器的带宽, 同时仍保持可接受的相位裕度。

通常, Cff 的较大值可提供更大的带宽改进。但是, 如果 Cff 过大, 前馈电容会导致环路增益交叉频率过高, 并且 什么是IQ Option以及它如何工作? Cff 相位提升贡献不足, 导致不可接受的相位裕度或不稳定性。

前馈电容的实际效果

(1)无前馈电容
如下图所示,无前馈电容设计时,当负载(绿色)由小增大时,输出电压(黄色)曲线出现震荡,且很久才趋于平稳。

(2)有前馈电容时
在同样的负载变化情况下,当有前馈电容设计时,输出电压很快输出平稳,且不会震荡多次。

前馈电容的选择

在这里插入图片描述

在数据手册中我们一般会看到如下描述:

上图中的VOUT就是DCDC的输出电压;R1和R2为反馈电阻;L为电感;COUT为输出滤波电容。

一般的方法:

参考:TI-Optimizing Transient Response of Internally Compensated dc-dc Converters With Feedforward Capacitor