Analysis of Shaped Pulse Transitions in Power Electronic Switching Waveforms for Reduced EMI Generation

Shaping switching waveforms in a 650 V GaN FET bridge-leg using 6.7 GHz active gate drivers

“…The damping appears to be equivalent to that of the 18-Ω scenario. This smoother waveform will contain lower-magnitude high-frequency components and therefore generate less EMI [10]. Active gate driving also reduces and softens the peak of i D2 .…”

“…Active gate drivers shape a power device's switching waveforms during the switching transient, which is typically achieved by continuously varying gate resistance [1] - [7], gate voltage [8] - [10], or gate current [11] - [17]. This is in contrast to conventional gate drivers that apply a fixed voltage step function via a fixed resistance.…”

Identification of the temporal source of frequency domain characteristics of SiC MOSFET based power converter waveforms

“…[6] demonstrates an 'S' shaped waveform which extends the roll off of the spectral components of the signal to 60 dB/dec at higher frequencies. This work also demonstrates that the idealized switching waveform would not cause any further switching losses.…”

“…Equations (5) and (6) show the break-frequencies for the trapezoidal waveform [1] and Equations (7) to (9) show those for the S-shaped waveform [6]. The break frequencies give the points at which the spectral envelope of the waveform transitions from one roll-off rate to a steeper one.…”

“…Other aspects, such as the waveforms smoothness, ringing and overshoot will dictate the high frequency performance. This paper will show that through the use of higher order models such as those discussed in [2], [4]- [6], it is possible to identify the time domain source of more complicated frequency domain characteristics than is possible with the trapezoidal model alone. An example SiC MOSFET based converter is considered and the relation of the losses and EMI performance investigated.…”