모델예측 전류제어 기반 고효율 부스트 컨버터PFC

Abstract

Nowadays, electric vehicles (EVs) are gaining attention as an alternative to internal combustion engine vehicles that use traditional fossil fuels, driven by environmental regulations and the move towards decarbonization. Simultaneously, demand for EV charging devices is growing as a key component of the electric vehicle market. Especially for charging purposes, the onboard charger is equipped with an AC/DC converter, and the power factor correction (PFC) converters are used as AC/DC pre-regulators. The main purpose of a PFC converter is to reduce the input current harmonics and achieve a high power factor and high efficiency. Accordingly, research on current shaping and switching loss improvement is being actively conducted for the original purpose of PFC converters. However, the control method of the conventional boost PFC converter adopts a fixed switching frequency, so it is limited in improving the switching loss. In addition, distorted current occurs under distorted voltage, which degrades converter performance. Therefore, this paper proposes a boost PFC converter based on model predictive current control to achieve both improved efficiency and robustness against voltage distortion. The control method of the conventional boost PFC converter adopts a fixed switching frequency, so it is limited in improving the switching loss. The proposed method operates with a variable switching frequency because it predicts the inductor current based on a cost function and then controls it. When this method is applied, the switching frequency is reduced near the peak voltage where the current is the highest, so it is facilitated to improve efficiency. In addition, since it detects the frequency of the input voltage and generates a sine wave internally, it is robust against voltage distortion. The proposed method confirmed the facilitation of efficiency improvement compared to the conventional predictive current mode control. To verify the effectiveness of the proposed method, simulation and HIL (Hardware-In-the-Loop) tests are performed using PLECS RT-box. In addition, experiment is conducted by configuring an experimental setup of a 3.3kW boost PFC converter based on the SiC power module.