如何绘制占空比和特定幅度变化的方波图？

Question

问题是：使用Matlab计算周期为1 ms的矩形脉冲波形的RMS电压。该波应具有0 V的最小峰值和4 V的最大峰值。计算“ ON”时间占空比的RMS电压为20％，50％和80％。还要计算一个相同电压电平的三角波的RMS电压（从0到4伏到周期结束时回到0伏）。

我有代码来计算所有这四个波的RMS电压，但是我需要绘制三个方波的图，我不确定该怎么做。

我知道square函数和dutycycle函数，但是我不知道如何实现它们，以便有一个特定的幅度（在这种情况下，为0到4） 。任何帮助将不胜感激。

% Calculation of RMS value for 20 percent
v_sum = 0.0; % Initial sum is set to zero
% for loop for one cycle
for k = 0.0:1.0:99.0
   if k < 20
       v = 4; % On period
   else
       v = 0; % Off period
   end
    v_sum = v_sum + v.^2; % Sum and Square are implemented
end
% Rms value calculation
v_rms_20 = sqrt(v_sum/100); % Root and Mean implementation
% Display the value
disp(v_rms_20)

%-----------------------------------------
% Calculation of RMS value for 50 percent
% Initial sum is set to zero
v_sum = 0.0;
% for loop for one cycle
for k = 0.0:1.0:99.0
   if k < 50
       v = 4; % On period
   else
       v = 0; % Off period
   end
    v_sum = v_sum + v.^2; % Sum and Square are implemented
end
% Rms value calculation
v_rms_50 = sqrt(v_sum/100); % Root and Mean implementation
% Display the value
disp(v_rms_50)

%-----------------------------------------
% Calculation of RMS value for 80 percent
v_sum = 0.0; % Initial sum is set to zero
% for loop for one cycle
for k = 0.0:1.0:99.0
   if k < 80
       v = 4; % On period
   else
       v = 0; % Off period
   end
    v_sum = v_sum + v.^2; % Sum and Square are implemented
end
% Rms value calculation
v_rms_80 = sqrt(v_sum/100); % Root and Mean implementation
% Display the value
disp(v_rms_80)

%-----------------------------------------
% Calculation of RMS value for triangular wave
v_sum = 0.0; % Initial sum is set to zero
% for loop for one cycle
for k = 0.0:1.0:99.0
   if k < 50
       v = 4*(k)/50; % Up trend period
   else
       v = 4*(100-k)/50; % Down trend period
   end
    v_sum = v_sum + v.^2; % Sum and Square are implemented
end
% Rms value calculation
v_rms_triangle = sqrt(v_sum/100); % Root and Mean implementation
% Display the value
disp(v_rms_triangle)

Answer 1

您可以设置幅度和电压范围，并根据幅度偏移和缩放square的结果。

square函数返回值[-1，1]。

• 添加1-将范围设置为[0，2]。
• 乘以幅度/ 2，将范围固定为[0，幅度]。

示例（基于square的MATLAB示例）：

t = 0:1/1e4:5; %Time (X axis).
cyc = 20; %Duty cycle
amp = 4; %Amplitude
cyc20_amp4 = (square(2*pi*t, cyc)+1)*amp/2; %Voltage (Y axis)

%Plot a graph
figure;plot(t, cyc20_amp4);title(['dutycycle=', num2str(cyc), ' amplitude=', num2str(amp)]);
xlabel('t');ylabel('V')

结果：