外文翻译基于Buck变换器的综合实验设计

基于Buck 变换器的综合实验设计
Buck 变换器最常用的变换器，工程上常用的拓扑如正激、半桥、全桥、推挽等也属于Buck 族，现以Buck 变换器为例，来阐述虚拟综合性实验的操作方法。

设输入直流电压(V IN )：15V ，输出电压(V O )：5V ，输出电流(I N )：6A ，输出电压纹波(V rr )：50mV ，基准电压(V ref )：1.5V ，开关频率(f s )：100kHz 。

Buck 变换器主电路如图1所示，其中R C 为电容的等效电阻。

图1 Buck 变换器主电路图
1.1滤波电感和电容参数设计
滤波电感电流脉动'
0.1*0.160.6o I I A ∆==⨯=
'2*20.6 1.2I I A ∆=∆=⨯=
估算滤波电感值()()3
1055
20.8310 1.210010
IN O O
IN s
V V V L H V If μ--⨯=
=
=∆⨯⨯⨯
滤波电容的内阻501.20.042PP Rc V I =∆==Ω
电解电容111(50~80)(50~80)(1190~1905)0.042
C F F F R μμμ=*
=*=
第一步首先建立交越频率f c0，在此频率总增益为0dB 。

然后选择误差放大器的增益，迫使总开环增益在f c0为0dB 。

下一步设计误差放大器的增益斜率，以使得总开环增益在f c0以斜率－1交越（图6.4）。

最后，调整幅频特性达到希望的相位裕度。

采样理论指出，为了闭环的稳定，f c0必须小于开关频率的一半。

但必须远远小于开关频率，否则有较大幅值的开关频率纹波。

因此，一般经验将f c0定为开关频率的1/4~1/5。

样选取f c0/f z =f p /f c0。

f z 与f p 之间分开越大，在f c0有较大的相位裕度。

希望较大的相位裕度，但如果f z 选择得太低，在100Hz 低频增益比选择较高频增益低（图6.8），这样对100Hz 信号衰减很差。

选取电路参数,fz=1/(2*pi*R1*C1) fp0=1/(2*pi*R0*C0) fp=1/(2*pi*R2*C2)
R1=R2=800O欧姆C1=C2=10nF
上面已经指出如果误差放大器具有单极点、单零点和一个原极点，它的幅频特性如图6.11所示。

现在证明一个误差放大器的传递函数如何推导，以及图6.7b电路确实具有一个单极点、一个单零点和一个原极点。

图6.7b电路的增益为
引入复变量s=jω，于是
经过代数处理
同时因为一般C 2<<C 1，则
经计算
G=(10^6+8S)/[16S(10^6+8S)]
具有式（16）传递函数的图6.7b 误差放大器在Venable 经典著作中一般称为2型放大器。

当输出滤波电容具有ESR 时，使得f c 0落在斜率－1的增益G 1的曲线（图6.6）上，应用2型误差放大器。

研究电路图6.7b 的传递函数可直接画出它的幅频特性（图6.11）。

式（16）指出这个电路（图6.7b ）在f p 0=(2πR 0C 0)-1
具有一个原极点。

在此频率以－1斜率向低频方向画一直线。

由式（16）在频率f z =(2πR 2C 1)-1电路有一个零点。

在f z 由斜线转成水平。

再由式（16）电路在f p =(2πR 2C 2)-1
有一个极点，在此频率f p 再由水平转向斜率－1。

PWM 增益
图6.1中由误差放大器输出到电感输入电压V y 的平均值V av 的增益是PWM 增益，并定义为G m 。

这样增益定义可能产生迷惑，直流电压V ea 随误差放大器的B 点的输入成比例变化，而V y 是可调宽的恒定幅值脉冲。

这个增益的意义和幅值说明如下。

图6.1中PWM 输出是直流电平V ea 与0~3V(实际上是0.5~3V)三角波V t 比较产生的。

在所有PWM 芯片中，产生两个相差180°的可调宽度脉冲。

在形成PWM 以后，经分频并送到两个分离的输出端。

在正激变换器中，仅用两个输出的一个。

在图6.1b 中，V ea ＝0,T on =0，在V y 的宽度为零，V y 的平均值就是V av ＝（V sp -1）(t on /T),其中V sp 是变压器次级电压，1为整流二极管压降，V av 也为零。

如果V ea 移动到3V ，在三角波的峰值，t on =0.5T ，V o ＝0.5（V sp -1）/T 。

则调制器的直流增益为V av 与V ea 的比值
电解电容R1*C1=50~80微法*欧（R1为滤波电容的内阻）
取 50微法*欧
△I=2*输出电流/10=2*6/10=1.2安培
R1=Vpp /△I=0.05/1.2=41.6毫欧
C1=50微法*欧/41.6毫欧=1200uf
瞎做的，一大拖屎堆出来的
！！！！！！！！！！！！！
后面的不对！！！！！！！！！！！！！！！！！！！！
增设单极点、单零点的PI补偿网络
增设单极点、单零点的Pl补偿网络，有的文献称为单极点、单零点补偿网络。

图1（a）所示即为增设单极点、单零点的PI网络电路图，图中Z1（s）＝R1，z2（s）＝（1/sC∥CR2+1/s C2）。

符号∥表示并联。

于是，增设单极点、单零点PI补偿网络的传递函数为
除了积分器1/s产生的极点s＝0外，还有一个零点-1/T Z，一个极点-1/T P，均位于左半S平面。

图1（b）为增设单极点、单零点PI网络的幅频及相频特性，图例中，零点频率fz为505Hz，极点频率fp为50kHz。

图1 增设单极点、单零点的PI补偿网络
图2为应用这种网络（其幅频特性为|Κ|）补偿后的效果。

调节对象为考虑电容ESR的Buck开关。

图2 Buck开关电源应用单极点、单零点PI补偿网络补偿后的Bode图
转换器幅频特|G丨，含有一个ESR零点；采用增设单极点、单零点的Pi网络后，Buck
开关电源的开环传递函数T。

的幅频特性|T0|＝较为理想。

低频段具有高增益，中频段以-1率穿越0dB线，保证系统稳定，高频段则快速衰减。

球传递函数画波特图、仿真图
About positioning error compensation
Controller manufacturers provide a facility which allows you to remove any errors in the machine positioning system by specifying compensation values for each machine axis. Both linear and rotary positioning errors may be compensated. By applying compensation you can reduce errors to such an extent that they are almost completely nulled and the accuracy of the machine is improved considerably.
Whilst this is an excellent concept, it must be understood that to obtain error compensation values, you must first be able to measure the small differences between the intended position of the moving part and its actual position, at various points along an axis. Fortunately a solution already exists; the combined use of a Renishaw laser interferometer system and the positioning error compensation software extension package.
The errors that need to be measured may be considered to be small, in the order of a micrometre or so, however, the cumulative effect of such an error along an axis can be quite considerable. Using the laser to measure these errors and the compensation software to record them, a table of measured errors at points along an axis can easily be obtained. These errors can then be translated into compensation values which the controller can apply as the moving part is moved along the axis.
The Renishaw positioning error compensation software is offered as an additional option to the standard Renishaw Laser10 calibration software. The software provides a 'step-by-step' user interface to guide you through the various stages of the error compensation procedure.
How a machine is compensated
To compensate a machine, you use the facilities provided by the positioning error compensation software to create a part program for the controller. This is a simple task; all you need to do is specify the target positions along the axis where you want to measure the linear error and the software creates the part program for you automatically.
Serial communication facilities are then used to transfer the part program into the controller. Once it is there, you set the computer into its data capture mode and start the part program.
The position of the moving part is monitored by the software via the laser interferometer. As the controller pauses at each target, the position of
the moving part is captured by the software, during a suitable dwell period, before it is moved on to the next target. This cycle continues until all targets are visited in the required sequence. The data gathering process is therefore totally automatic; all you need to do is to observe it.
After capturing the data, you can analyse it to see the linear positioning error along the axis. This is performed using the standard data analysis software rather than facilities in this additional package.
If you then decide that compensation is required, you specify start and end points which define the part of the axis you want to compensate for linear errors, and either the number of compensation values you require or the distance between each consecutive compensation point. The software then calculates the error compensation values. You can then enter these into the controller either manually, by using the controller's data entry keys, or automatically, by using the serial communication facilities.
You should then check that the compensation applied by the controller meets your tolerance requirements. To do this, you run the part program and capture the data again. If, after analysing the compensated data, you want to reduce the errors further still, you can increase the number of targets at which linear errors are measured and start again by producing a new part program.
Alternatively, if you are satisfied with the compensation, you should instruct the controller to perform several runs, usually five, where the moving part is moved to a number of random targets in each run. By doing this, you can obtain data which complies with one of the applicable national or international standards such as ISO 230-2.
After a data capture session, the errors measured at each target can be stored in a data file. It is therefore possible to maintain a record of errors in an axis before and after compensation has been applied. These data files can be copied to a floppy disk and archived for security and future reference. If, for any reason, the compensation values stored in the controller become corrupted at a later date, you can easily restore them by transferring the data contained in some of the data files.
Requirements
In order to use the facilities provided by the positioning error compensation software package, you must use the following:
•An IBM PC or compatible computer with at least 32 Mb of RAM, one serial communication port, and a SVGA colour monitor. The software does not support
monochrome displays. A hard disk is essential; the software uses a number of large files
and, during the course of performing error compensation, you will be creating several
new files. If you are using the Renishaw ML10 laser, the PC10 control card, for
connecting the computer to the laser, must be fitted. The software can also be used with
other Renishaw hardware and other lasers.
•An RS232 serial communication cable for connecting the computer to the data entry port on your controller.
Note:Some PCs use the standard 25-way D-type connector whilst ATs and portables generally use a 9-way connector.
The RS232 cable connections required for your controller are detailed in the Interface Requirements topic of the error compensation user guide for the controller.
•The Renishaw ML10 or similar laser, tripod and linear optics.
•Windows 95, Windows 98 or Windows NT4 or above.
•The standard Renishaw linear data capture and analysis software.
This equipment is interconnected as shown in Figure 1 below:
Figure 1 - System interconnections
Options
Two optional items of equipment may be used to aid the task of measuring linear errors. These are:
•An EC10 environmental compensation unit
• A printer
The EC10 environmental compensation unit allows the software to continually and automatically compensate for variations in environmental parameters that affect the refractive index of the air through which the laser beam passes. If this is not used, environmental parameters (air and material temperature, humidity and air pressure) must be entered manually.
It is useful but not mandatory to have a printer to obtain hard copy of data at various stages during an error compensation run. For example, some of the data files produced by the software can be printed out and examined, perhaps to find out how the controller is currently configured, or perhaps to examine a graph which shows the linear errors before and after compensation. If a printer is available, this type of data can be printed and examined whilst the computer is performing another task.
Error compensation package
General
The software required to perform automatic positioning error compensation is provided as an additional software package to the standard Renishaw Laser10 calibration software. Because controllers operate in different ways, i.e. they interpret machine parameters differently and use different conventions in their part programs, there is one software package for each type of controller.
In order to perform positioning error compensation on a machine with a particular type of controller, you must first install the software for that controller. Thereafter, when you start the positioning error compensation software from the Renishaw program group, you can then select the option for your machine's controller.
Software
The software required to carry out positioning error compensation is supplied on CD-ROM.
Please note that there is a separate CD-ROM for each model of controller. Each CD-ROM contains 'generic' error compensation software components and also specific components to support the particular model of controller.
Installing the software
Installation is performed by using 'setup'. This program copies the files from the CD-ROM into a directory on your computer's hard disk. This
directory is termed the RENISHAW directory.
For details of the installation procedure, refer to the Software installation topic of the on-line user guide.
Other files required
Machine definition file
In addition to the software for your particular type of controller, another file called a machine definition file (MDF) is installed. This file contains a part program template and the default settings for the RS232 interface. The MDF file is given the same name as the associated controller software that uses it.
For example:
MAZAK.MDF is the MDF file for Mazak M-Plus, M32 and M2 series controllers.
Configuration file
The CURRENT.RCF file contains current configuration information and
is used by the capture software WINCAPT.EXE and by the error
compensation software GEC.EXE. This is the default name for the file
as supplied by Renishaw but other RCF files can be created by changing the configuration and saving it in a file with a different name. Language files
Files such as ENGLISH.WLE, FRENCH.WLE and DEUTSCH.WLE contain the text for the menus, dialog boxes and help and error messages used by the capture and analysis software WINCAPT.EXE and WINANAL.EXE.
Similarly, files such as GECE.WLF, GECF.WLF and GECD.WLF contain the text for the menus, dialog boxes and help and error messages used by the error compensation software GEC.EXE.
Error compensation software facilities
The positioning error compensation software provides facilities, additional to the Laser10 calibration software, that enable you to measure the positioning errors along an axis of a machine. Once the errors have been measured, the software nulls them by generating a table of compensation values. These values are then transmitted directly into the controller. In this way, the errors in one machine axis can be compensated. By repeating the process on the other axes, a complete machine can be compensated.
The positioning error compensation software enables you to perform the following:
•Create a part program for the controller. Such a program instructs the machine to move to selected points along an axis and pause for a few seconds whilst the calibration software
measures the positioning error.
•Automatically measure the position of the moving part relative to its reference position, at each of the points specified in the part program, and store these readings for error analysis later.
•Compile a table of error compensation values for the controller, to null out the difference between the actual position of the moving part (measured by the laser interferometer
system) and the theoretical controller derived position.
•Replace the existing error compensation values in the controller with the new set of values by sending them via an RS232 link.
•Store the error compensation values so that they can be examined by optional data analysis software.
•View, edit and print various data and configuration files.
•Use simple communications facilities to interrogate the controller.
Data file types
It should be appreciated that creating a part program and measuring the error at various points along the axis of a machine involves the creation, capture and maintenance of a variety of data. This data is held in files which are stored on the computer hard disk. Due to the variety of data used, it is stored in several files, each being identified by the extension to its name, i.e. the three characters that follow the full-stop separator after the filename. Six types of file with the following extensions are used:
RPP Renishaw part program file
This is normally created by the positioning error compensation software but you can create your own using a text editor. It contains the commands that instruct the controller to move the machine moving part. Part programs created automatically by the compensation software are used to position the moving part at various points along a particular axis, hence allowing the software to measure the positioning error at those points. It is very easy to create a part program because you do not need to know the specific commands that the controller uses to position the moving part or change its feed rate. If necessary though, you can create and retain a library of part programs for use whenever a machine is compensated, allowing you to compare results over a period of time.
Once an RPP file has been produced, it can be transmitted, via an RS232 communications link, to a controller where it can be selected and run.
RTL Linear data file
This is created by the laser calibration software during data capture. It contains a list of positions where the controller stops the moving part of the machine (i.e. the targets), and the error that was measured between each of these target positions and the actual position of the moving part.
The data contained in this type of file is essentially a record of the errors measured when an axis of a machine is compensated. If several axes are compensated in one session, an RTL file is produced for each axis. It is recommended that RTL files are copied to a floppy disk after compensating an axis or all axes of a machine. This disk should be stored away in a safe place in case the data needs to be referred to at a later date.
OMP Original machine parameters file
This file is created by the error compensation software. The data it contains can be obtained by downloading it from the machine controller via an RS232 communications link, transferring it by floppy disk or entering it manually. Downloading is the preferred method but the actual method used depends upon what the controller supports (e.g some controllers don't support an RS232 link). The file holds the current values of the controller machine parameters. If an axis has been compensated on a previous occasion, the file also holds the compensation values that are currently being applied by the controller. If an axis has not been compensated, the compensation values are zero.
The OMP data is specific to a machine and normally should only need to be generated once. The file is held on the computer hard disk and may be recalled at subsequent error compensation sessions.
TBL Axis table file (error compensation session file)
This file is created by the error compensation software and contains information about each compensated axis. The information includes the extremities that define the portion that has been compensated, and the number of error compensation values that have been calculated which lie between these extremities. It also contains details of which NMP files are used by the machine, and this enables any existing compensation session to be continued. Overall, it provides a summary of how the axis has been compensated.
NMP New machine parameters file
This file is created when one or more axes of a machine are compensated. An NMP file is used by the error compensation software to store the values of machine parameters that need to be changed together with the new compensation values, after the software has calculated them for each axis.
MDF Machine definition file
This file has been created by Renishaw and contains a variety of data which is specific to one particular type of controller. The data identifies default values for some of the extended facilities and controller specific commands that are used when a part program is created.
All of these files are stored in ASCII format and hence can be read and printed by any text editor or word processor. Because these files are text-based, they can also be edited. However, it should not be necessary
to edit any of them except possibly the RPP and/or MDF files. None of
the other files should be edited; if you do so, the results could confuse the software.
When editing an RPP file (a part program), you should fully understand
the commands that the controller reads from a part program otherwise, when it is run, the controller may perform unexpected movements.
In most circumstances, there are only two sections of the MDF file which
you may need to edit. One of these contains the default settings used for the RS232 communications link to the controller.
Experienced users may want to edit the second section of the MDF file which contains template information used by the software to create part programs. By editing this section, you can add certain controller commands (G-codes) which set up the controller according to your needs. Refer to the Customising the machine definition file topic for further information. However, do not edit these files unless you are totally familiar with the commands of your controller (i.e. its G-codes) and their actions.。