RU-vid autoplay is a wonderful thing. Never would have found this channel without. I love visualisations of the drive waveform, it gives a really good image of what SPWM is supposed to do and how it does it. Also the sounds are uncannily similar to the actual trains.
for english viewers: 0:09 Seibu 6000 series (Hitachi GTO) 1:04 Tokyu 5050 series (Hitachi IGBT) 2:04 Tobu 9050 series (Toyo GTO) 3:02 Tobu 50070 series (Hitachi IGBT) 4:00 Teito 7000 series (Hitachi IGBT)