Hitachi IGBT VVVF | Class 385 Traction Sound | PWM Inverter - Class 385 Inductor Recording

Описание: Note that the inductor sound heard in the first chapter is not the audio that was used to visualise the waveform in Sonic Visualizer. The reference sound used for the visual is significantly cleaner. But because it sounds worse to listen to, a harmonic-enhanced hybrid between the raw recording and processed clip has been edited together for you to listen to. For the pulse modes, please monitor the waveform carefully - zoomed out more than usual to help you find the zero-crossings.

The Class 385 has been very challenging to record a clear waveform of. The TIC in a four-car formation contains two traction converters and the auxiliary power supply unit together as one big integrated system. That makes auxiliary noise and the transformer harmonics nearly impossible to escape. It also has not helped that the Class 385 lacks a lot of flux-conducting steel. It is possible to record the cables from the three-car formation where one TIC drives "1.5" motors. I tried this, but the signal strength was very weak and had the effect of raising the noise floor which is difficult to clean since the noise isn't necessarily random. This recording was, instead, taken from the induction motor with all of the grid noise to boot. It provided a much stronger signal at the cost of having to heavily and manually scrub the recording clean of the grid harmonics, etc.

Pulse modes include: 525Hz - 725Hz carrier ramp, some sync modes which look to be the same as found with the Class 80X (9P, 3P, 1P) except that 9P enters earlier and 1P isn't clocked - not at least until very high speed and load if decided by the TCU. It's likely because, given the lower load inertia of the Class 385 AT200 vs the Class 80X AT300, less torque is required to achieve the same performance and therefore the maximum voltage output is not require.

Also know that the Class 385 also does the thing where the carrier ramps up and down a bit with the proportion of output voltage, but it's much more tame than with the likes of the Class 465 or Class 395 and looks to also be parametrised by the fundamental speed and not just modulation index (an improvement).

00:00 Electromagnetic
02:12 Natural Sound
04:23 Electromagnetic & Natural Sound

Noise reduction post-processing:
Heavily manually scrubbed of noise patches
Note that the sound heard in the video isn't the waveform reference used for visuals

Equipment used:
2x 1000mH telephone pickup coil to single pole TRS 3.5mm
Tascam DR40X

Class 385 Traction Motor Sound
Class 385 Motor Sound
Class 385 Traction Sound
Class 385 Sound
Class 380 Traction Motor Sound
Class 380 Motor Sound
Class 380 Traction Sound
Class 380 Sound
Class 800 Traction Motor Sound
Class 801 Traction Motor Sound
Class 802 Traction Motor Sound