STUDENT PROJECT: Design and Test a PFC Controller Using PLECS Simulation and a Prototype PCB

When designing frequency converters for single phase heat pump applications as PFC front-end is often required to draw a sinusoidal current from the supply grid.

A PFC (Power Factor Correction) front end shapes the grid input current to be sinusoidal and in phase with the single-phase grid voltage. Thus, the total apparent power consumed from the grid is minimized. The output of a PFC front-end is a DC voltage that is supplied to the DC-link capacitors in the frequency converter.

The DC voltage amplitude from the PFC can within limits be controlled and adapted to the actual needs of the frequency converter. Limiting the DC-link voltage to what is needed will reduce the losses in the frequency converter.

A prototype PCB with PFC components and a frequency converter is available at Bitzer Electronics.

Methodology
First a literature study of common PFC control strategies with an eye on the existing hardware is needed. Included in the study should also be “difficult” operating conditions like discontinuous mode and low power mode. Based on this a couple of control strategies can be evaluated using the simulation software PLECS.

A selected control strategy can then be implemented in the firmware (C-code) and tested in lab.

Primary objectives
// Evaluate a few PFC control strategies by simulation.
// Implement a chosen PFC control strategy using an existing prototype PCB.
// Test the implemented control strategy in lab.

Secondary objectives
// Meausure energy savings by adapting the DC-link voltage to the requirements of the frequency converter.

Prerequisite skills
// Knowledge of C++ or a similar OOP language
// Understanding of control system design

Supervisor
Hans Jørgen Nørgaard (Software Engineer, Control Team)
[email protected]

Department: Control Team

Location: Kærvej 77, 6400, Sønderborg, Denmark