Shaping SiC MOSFET voltage and current transitions by intelligent control for reduced EMI generation

In power converters, the fast switching of the power conversion components results in rapid changes in voltage and current, which results in oscillations and high-level electromagnetic interference (EMI), so the power components become a source of internal electromagnetic interference. Taking SiC Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) as an example, an intelligent control method to suppressing interference sources is proposed in this paper. The combination of open-loop and closed-loop methods can simultaneously reduce the electromagnetic interference generated by voltage and current. Firstly, this paper analyzes how to select a reference signal. The relationship between the time domain and the frequency domain of the noise signal is analyzed. The convolution of the trapezoidal signal and the Gaussian signal is selected as the reference signal, which is named S-shaped signal in this paper. The S-shaped signal has continuous infinitely conductive characteristics, so its spectrum has a large attenuation in the high frequency region. Secondly, a new topology is proposed. Based on the closed-loop gate control, a current control signal is added, which can simultaneously shape the output voltage and control the output current slope. Both the simulation results and the experimental results show that the output voltage can follow the reference signal, S-shaped signal, and the slope and overshoot of output current can be changed. Compared with classical gate driver method, the spectrum of output voltage and output current obtained by the method proposed in this paper has a large attenuation, in other words, the electromagnetic interference is significantly reduced.