A Digital Predictive Constant Frequency Controller For High Frequency 3-Phase Silicon Carbide PFC Rectifier

Inhalt:
Commerciality available SiC devices allow for a 2-5× increase in switching frequencies leading to a substantial reduction of the value of control inductor required between the grid and the converter in grid-connected applications such as 3-phase PFC rectifiers. While this is beneficial from a cost and power density perspective, it may also lead to control challenges due to the reduction of the impedance between the grid and the power converter. These challenges are aggravated in the case of polluted grids (i.e., harmonics). These control challenges limit how much the mentioned grid inductors can be reduced on a practical power converter. As such, improved control schemes are needed to work effectively under low grid-side impedance conditions. This paper presents a digital implementation of Constant Frequency Predictive (CFP) control based on system parameters for 3-phase, six-switch PFC rectifier which leads to a robust control similar to the robustness afforded by analog hysteresis controllers. The new control Scheme is simulated in PLECS and experimentally verified on a 7.5kW, 3-phase PFC rectifier using a 2-level six-switch SiC Module.