DC-DC Converter Control

What Is DC-DC Converter Control?

DC-DC converters are power electronic circuits that convert direct current (DC) from one voltage level to another. DC-DC converters come in various topologies, including buck (step-down), boost (step-up), buck-boost (capable of both stepping up and down), and the more complex single-ended primary-inductor (SEPIC). In DC-DC converter control, high-efficiency voltage conversion is achieved by rapid switching of semiconductor power devices, such as thyristors, MOSFETs, IGBTs, and diodes that periodically charge and discharge energy storage elements (inductors and capacitors). DC-DC converters are an integral part of modern electronics, enabling the use of batteries and other DC power sources within a wide range of DC voltages required by different components. Control methods for these converters are essential to maintain the desired output voltage and ensure efficient power management across various load conditions.

DC-DC Converter Controller Design

Power electronics engineers can use MATLAB® and Simulink® products to model analog electronic components and digital control algorithms in the same simulation environment. Engineers choose digital control of a DC-DC converter when they need to regulate the output voltage or current in the presence of varying load conditions and input voltage fluctuations. Closed-loop simulation of the power stage and the control algorithms enables you to evaluate and verify design choices before implementing the controller.

Using simulation as part of these key design tasks helps ensure that your DC-DC converter control system is robust while also meeting design specifications:

  • Designing a feedback controller for voltage regulation
  • Optimizing RLC components concurrently with the controller design
  • Estimating the steady-state and dynamic characteristics of the semiconductor switches
  • Analyzing dynamic performance and power quality
  • Prototyping and implementing the digital controller on an embedded microprocessor or FPGA
Block diagram showing the power stage and digital controller for boost converter control.

Simulink block diagram of boost converter control.

Simulink enables you to design, validate, and implement your DC-DC converter control system knowing that it will work as intended when you begin hardware testing. You can:

  • Model the power stage using standard circuit components or a prebuilt converter block.
  • Simulate the converter model at different levels of model fidelity: average models for system dynamics, behavioral models for switching characteristics, and detailed nonlinear switching models for parasitics and detailed design.
  • Design, simulate, and compare different controller architectures, including voltage mode control and current mode control.
  • Apply classical control techniques such as interactive loop shaping with Bode and root-locus plots on nonlinear converter models that include switching effects using methods such as AC frequency sweeps or pseudorandom binary sequences (PRBSs) as well as other system identification techniques.
  • Autotune controller gains in single or multiple feedback loops using automated tuning tools. Design gain-scheduled controllers to account for operating point variations.
  • Test real-time execution of your power converter controls in hardware-in-the-loop (HIL) setups before verifying them on a hardware prototype.
  • Identify and correct common errors in control design by generating test cases and prevent potential damage to expensive hardware prototypes.
  • Generate optimized and stable C/C++ control code for implementation on microcontrollers or synthesizable HDL code for FPGA programming or ASIC prototyping.

Engineers can use MATLAB, Simulink, and Simscape Electrical™ to design, simulate, and test DC-DC converter control algorithms in the same environment. Detailed modeling enables you to evaluate the converter performance under various scenarios and visualize the results in real time.

Using Embedded Coder®, you can generate production code for the controller and perform hardware-in-the-loop testing to assess the DC-DC converter performance under various operating conditions. This approach helps designers mitigate risks, optimize performance, and accelerate the path from concept to market-ready solutions.

To learn more about how to design DC-DC converter control with MATLAB and Simulink, see Simulink Control Design™, Control System Toolbox™, and HDL Coder™.

See also: modeling and simulation, Simulink Design Optimization™, Simulink Real-Time™, power electronics simulation, dual active bridge