In the realm of modern electronics, the buck converter stands as a staple in efficient power delivery — stepping down voltages while maintaining control, stability, and performance. Whether it’s optimizing energy usage in portable devices or powering precision systems, buck converters play a critical role in today’s circuitry.
This blog explores how Ansys simulation tools, particularly Ansys PExprt and Simplorer, can be leveraged to model and analyze buck converters at the system level. We’ll walk through the process of designing the converter’s magnetic components, exporting the design to Simplorer, and evaluating both open-loop and PID-controlled performance. This simulation-driven approach allows engineers to validate converter behavior before hardware prototyping, saving time and improving reliability.
Step 1: Model preparation and define input/output parameters for the buck converter in ANSYS PExprt
Launch PExprt --> Select Buck under Converter Based Inductor.
Input and output parameters are set as shown below. Input voltage: 42 V. Output voltage: 12 V.
Drag and drop materials to Design Library and assign materials for the Cores/Bobbins/Wires/Material.
Under Modeling Options tab, select Show all solutions. After the analysis is completed, all valid design will be listed.
Step 2: Start the design process
Go to Calculations --> Start Design Process. PExprt will find all the designs that can meet the requirements. This process will only take a few seconds.
Step 3: Select one design of interest and generate FEA and 1D models
In this example, the design with the lowest window filling is selected.
Go to Modeler --> Generate Model --> Generate FEA 2D based Model (without capacitive effects)
Start the model generation process by clicking "Start".
Once the parameter extraction is completed, we can exit the curve fitting process and it will bring us back to PExprt interface. We can save and close PExprt model.
Step 4: Create an open-loop circuit in ANSYS Simplorer
We need to launch ANSYS Simplorer from ANSYS Electronics Desktop and build the circuit for the buck converter.
We can find all the components from the Component Libraries in Simplorer. Users can find the Component Libraries by going to View --> Component Libraries.
We simply need to drag and drop the components in Simplorer and connect them. The complete open-loop circuit is shown below (without the buck converter).
The load (shown in the circuit above) is a variable. A step load is applied at 1 msec to reduce current and drive converter to discontinuous mode.
Step 5: Add the 1D buck converter model into the circuit
Go to Twin Builder --> Add Component --> Add PExprt Staci Component
Select the sml file from the PExprt folder:
Drag and drop the PExprt 1D component to the right position so that it is connected to the circuit. Now we can analyze the model in open loop. As expected, there is a large spike of the output voltage since there is no control loop.
Step 6: Add PID controller in the circuit
The PID controller can be found in the Component Libraries: Simplorer Elements --> Multiphysics --> SMPS --> Controllers
The final circuit with PID controller is shown below (with results). With the PID controller, the spike at 1 msec becomes much smaller. The output voltage is 12 V which meets our requirement.
The video below walks through these steps in detail.
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Ozen Engineering Inc. leverages its extensive consulting expertise in CFD, FEA, optics, photonics, and electromagnetic simulations to achieve exceptional results across various engineering projects, addressing complex challenges such as antenna design, signal integrity, electromagnetic interference (EMI), and electric motor analysis using Ansys software.
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