DC-DC LLC Converter

This example shows a DC-DC LLC power converter with frequency control. The Controller block implements a simple integral control in Simulink™. This integral control achieves a nominal output voltage, specified in the variable Vout_nominal. The Output scope shows the frequency control signal, the output voltage, and the reference value for the output voltage. During startup, the reference value ramps up to its desired setpoint. The design of the LLC powertrain is computed automatically using the first harmonic approximation.

This model contains two variants for the power electronic switches. The detailed version includes a MOSFET with nonlinear characteristics. The abstract version uses a piecewise linear model with an ideal switch, body diode, and output capacitance. The abstract version provides very similar behavior and quicker simulation.

Model

Power Electronic Switch - Detailed Variant

To enable the detailed version, in your model click on "Detailed - MOSFET". Alternatively, at the MATLAB® Command Window, enter:

DCDCLLCConverterSetAbstractDetailed(bdroot,'Detailed');

Power Electronic Switch - Abstract Variant

To enable the abstract version, in your model click on "Abstract - Ideal Switch". Alternatively, at the MATLAB® Command Window, enter:

DCDCLLCConverterSetAbstractDetailed(bdroot,'Abstract');

Simulation Results from Simscape Logging

This plot shows the output voltage as compared to the reference voltage. It also shows the variation in switching frequency as it is adjusted by the control system to track the reference voltage.

These plots show the behavior of the abstract models and the detailed model. The results are very similar, indicating that you can use the abstract models without a significant loss of accuracy.