LTspice .Subckt(1) PWM发生器

xutong

LTspice .Subckt(1) PWM发生器 [复制链接]

任务要求：

1. 两个输出PWM_H,PWM_L,一个接地
2. 开关频率100Khz
3. 输出占空比约等于50%
4. 可以设置死区
5. 输出电压为5V

设计步骤

步骤1：

找我们要的器件，既然PWM是时间相关的电压源，我们找电压源即可。

步骤2：

选定了V source ，因为V source 提供了多种电压输出模式的选择。

步骤3：

根据V source 的描述直接选用 PULSE模式，直接将其初始代码拷贝到我们的subckt 里面

* design by xutong * define a PWM Generate * Name is PWM_G means PWM Generate *              PWM output+ *              |  PWM output- *              |  |  Ground .subckt PWM_G PH PL GND Vxxx n+ n- PULSE(V1 V2 Tdelay Trise Tfall Ton Tperiod Ncycles) .ends

步骤4：

根据描述添加一些小细节

* design by xutong * define a PWM Generate * Name is PWM_G means PWM Generate *              PWM output+ *              |  PWM output- *              |  |  Ground   .subckt PWM_G PH PL GND *in this here V1 is Vinitial V2 is Von *Ncycles remove always have *Vxxx n+ n- PULSE(V1 V2 Tdelay Trise Tfall Ton Tperiod Ncycles) *                                   DT=0.2us Vph1 PH GND PULSE(0 5 1m 0.01u 0.01u 4.8u 10u) *          if function is an operation,you need to add{}                               Vpl1 PL GND PULSE(0 5 {1m+5u} 0.01u 0.01u 4.8u 10u) .ends

步骤5：

拖入LTspice 生成模块

步骤6：带入仿真

符合我们设想的样子。但是这个用起来还是麻烦，不能直接控制死区，每次改定义的参数非常麻烦所以需要引入.TEXT类似于C语言的宏定义。

Text 使用说明

.TEXT -- User-Defined Strings Syntax: .text <name>=<string literal> Example: .text DIODE = "1N4148" The .text directive allows the creation of user-defined strings. It allows associating a string with a name. That name can be used, e.g., a model or subcircuit name and then by changing the string associated with the name, a different model or subcircuit is used throughout the simulation. The .text statement can be included inside a subcircuit definition to limit the scope the string value to that subcircuit. Text substitution evaluation is done before the expanding subcircuits to a flat netlist. To invoke text substitution and text expression evaluation, enclose the expression in pipe, '|', characters. The enclosed expression will be replaced with string value of the name inside the pipes. Below is an example using both a global scope and local .text definitions. * V1 1 0 PULSE(0 1 0 1u 1u .5m 1m) R1 |node| 1 |"1" + "K"| C1 |node| 0 |foobar| X1 2 div 0 NIX .text node="2" .text foo=".1" bar="u" .text foobar = foo + bar .tran 3m .text top="100k" .text bot="100k" .subckt nix a b c .text bot="1Meg" R1 a b |top| ; uses global scope definition of top R2 b c |bot| ; uses locally scope definition of bot .ends nix .end And below resultant circuit after .text processing and subcircuit expansion. * v1 1 0 pulse(0 1 0 1u 1u .5m 1m) r1 2 1 1k c1 2 0 .1u r:1:1 2 div 100k r:1:2 div 0 1meg .tran 3m .end Note that pipe characters can include string literals, i.e., |"1" + "K"| is resolves to 1K. This will only happen if there exists at least one .text statement in the netlist. This is because .text is a new feature in LTspice. If there are no .text statements, the pipe character has no special meaning in the interest of running existing simulation in the same way

添加宏定义后的模块

* design by xutong * define a PWM Generate * Name is PWM_G means PWM Generate *              PWM output+ *              |  PWM output- *              |  |  Ground .subckt PWM_G PH PL GND *in this here V1 is Vinitial V2 is Von *Ncycles remove always have *Vxxx n+ n- PULSE(V1 V2 Tdelay Trise Tfall Ton Tperiod Ncycles) *setting  dead time and frequency,Duty                       .text DT="1u" .text Freq="30k" .text Duty="0.5" Vph1 PH GND PULSE(0 5 1m 0.01u 0.01u {{1/|Freq|}*|Duty|-|DT|} {1/|Freq|}) *          if function is an operation,you need to add{}                               Vpl1 PL GND PULSE(0 5 {1m+{1/|Freq|}/2} 0.01u 0.01u {{1/|Freq|}*|Duty|-|DT|} {1/|Freq|}) .ends

仿真结果符合我们的设计.

OK 今天就先聊到这里，拜拜~

邮箱 xutong@zjbtie.com

 

bmahu001

不错，有创意啊。

xutong

bmahu001 发表于 2022-6-26 15:25 不错，有创意啊。

过几天在更新一些