How to Pass Input from Python Script to Simulink Model

I had one DC-DC converter simulink model available with me and I am using MATLAB WITH PYTON to run that mode;. I had write down the code but i am facing an issue like my input to simulink model in form of (t,u) is not passing correctly and because of this error was comming. Please help me to fix this issue.

Detail code is as follow:

import matlab.engine

import numpy as np

import matplotlib.pyplot as plt

# Start MATLAB engine

eng = matlab.engine.start_matlab()

# Load the Simulink model

eng.load_system('VMC_BOOST3')

# Define the fixed duty cycle value

duty_cycle = 0.4 # 40% duty cycle

# Define time vector

t = np.linspace(0, 0.05, 100)

# Define input signal (single variable for model)

u = np.full_like(t, duty_cycle) # Constant input signal at duty cycle

# Convert to MATLAB format

time_matlab = matlab.double(t.tolist())

input_matlab = matlab.double(u.tolist())

# Combine time and input into a single matrix

external_input = matlab.double(np.column_stack((t, u)).tolist())

# Pass these to MATLAB workspace

eng.workspace['external_input'] = external_input

# Run the Simulink model and capture outputs

print("Running Simulink model...")

sim_out = eng.sim('VMC_BOOST3', 'ExternalInput', 'external_input', nargout=1) # Replace with your Simulink model name

# Retrieve the output voltage (Vout) and time data

yout = eng.getfield(sim_out, 'yout') # Access the yout variable

time = eng.getfield(sim_out, 'tout') # Retrieve time data

# Convert yout and time to NumPy arrays

yout = np.array(yout) # Convert MATLAB array to NumPy array

time = np.array(time)

# Extract Vout (second column of yout)

Vout = yout[:, 1] # Second column corresponds to Vout

# Compute the average value of Vout

average_Vout = np.mean(Vout)

print("Average output voltage (Vout):", average_Vout)

# Plot the output voltage over time

plt.figure(figsize=(10, 6))

plt.plot(time, Vout, label='Output Voltage (Vout)', color='blue')

plt.axhline(y=average_Vout, color='red', linestyle='--', label=f'Average Vout: {average_Vout:.2f} V')

plt.xlabel('Time (s)')

plt.ylabel('Output Voltage (V)')

plt.title('Boost Converter Output Voltage')

plt.legend()

plt.grid(True)

plt.show()

# Stop MATLAB engine

eng.quit()

[Hitesh]

Hi @ASHISH,

Could you include the error message along with the 'VMC_BOOST3' sample model? This will help in reproducing and addressing this issue.

Answer 1

[Simon]

Hi Ashish,

As I understand, you’re running a Simulink DC-DC converter model from Python. Your code seems fine, but the Simulink model must be configured correctly. Without the exact error or model details, I’ve tried this with a sample DC converter model. Please ensure your model setup matches the code’s requirements:

• Add an Inport block at the top level of your Simulink model.
• Connect the Inport to the part of the circuit where you want the duty cycle input to be applied.
• Make sure the Inport block is configured for a scalar signal (since u is a scalar).
• The external input should be a 2-column matrix.
• The simulation stop time must match the last value in your time vector t.
• If the To Workspace block is not set up to log to Simulation Output, you won’t get your results back in Python.

Any of these issues could cause the error. If not, please provide more details.

Please find the attached image to cross-check your model, and refer to the following documentation for more information:

https://www.mathworks.com/help/simulink/python-code-integration.html

Hope this helps!