[Inductor-Recorded Traction Motor Sound / モハラジオ録音] SEPTA Silverliner V [Mitsubishi IGBT-VVVF]

#モハラジオ #VVVFインバータ #SEPTA
Car Type: SEPTA Silverliner V
Traction: Mitsubishi Electric 3-Level IGBT-VVVF
Asynchronous (Dipolar Modulation → Unipolar Modulation) → 3P → 1P
Asynchronous Mode Carrier Frequency:
①Set to increase from 470 Hz to 920 Hz, depending on the inverter frequency (w/ RCFM).
②Only for the dipolar modulation part, set the carrier frequency to 1/2 compared to the setting of ①.
③For the dipolar modulation, the most emphasized component is around four times the carrier frequency.
　On the other hand, for the unipolar modulation, the most emphasized component is around twice the carrier frequency.
　This factor and the factor ② make the most emphasized components sound connected.
Sound Characteristics:
The pulse mode transition itself is a standard Mitsubishi 3-level IGBT, but for the dipolar modulation, a type of PWM that emphasizes the four-times carrier frequency component is used.
Mitsubishi has been using this type of PWM since the late 2000s, and it is also used in Japan in some of this manufacturer's hybrid SiC-applied VVVFs and in some of the VVVFs for Shinkansen that are thought to be made by them.
Also, when switching between dipolar and unipolar modulation, the switching does not occur at once during both acceleration and deceleration, resulting in chattering.
This characteristic is also commonly seen in VVVFs for Shinkansen that are thought to be made by Mitsubishi, and since this car is for AC sections (12 kV, 25 Hz), it is likely that the settings that cause this behavior have been inherited from them.
The inductor-recorded sound source of this vehicle has already been posted by the fellow error46147 (since it is a longer sound source, it contains various behaviors and there are many highlights), but I have uploaded it myself this time to emphasize this chattering behavior and to mention it in a video I plan to post in the future.
• SEPTA Silverliner V VV...
The AC traction PWM sound shown in this video is recorded by a sensor. This sensor is made by myself just using a 100mH inductor.
Due to the resolution of the spectrogram software, the frequency displayed in this video may include some error. Thank you for your understanding.
This sound is recorded in March 2019.
Sorry, I am NOT taking requests for recordings.
Posted by Ebara Express
X (Available in Japanese; translate please!)
/ vvvf_tokyu2000
Website "VVVF Database" (Available in Japanese; translate please!)
vvvfdatabase.st...
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[@nickloh912]

Thank you for all your videos (and especially for the detailed explanations that accompany each one). I'm glad I'm not the only one who finds these noises interesting. Philadelphia is my home town and I spent a lot of time riding these to and from college. I always wondered why they did not have the very obvious ramping noises like the NYC M7s despite also having Mitsubishi propulsion.

[@ebaraexpress7260]

Thanks for watching! Yes generally 3-level IGBTs are quieter than 2-level ones. Also I have posted other SEPTA cars, so hope you will also enjoy that!

[@KuMoHaVVVF]

very interesting to see the unipolar/dipolar methods of control outside of japan, never knew of any overseas example

[@Jones5121]

0:15 sounds sort of like the direct self control that some german locomotives use (class 101 and 145 come to mind)

[@viciadoemdorflex]

Could youmake a video with the CPTM 2500 and 9500 series? Thanks 🙏🏻🙇🏻‍♂️❤

[@TUbe-bv4fy]

He doesn’t accept any requests

[@goofyahhnerdyy]

Can you do WMATA 7000 series next?

[@ebaraexpress7260]

@@goofyahhnerdyy Apologies, I don't take any requests. However, that car's sound has already been posted here by my fellow: th-cam.com/video/hHyP-9I8Y3s/w-d-xo.htmlsi=aHtLq1S19fHkvG8u

[@goofyahhnerdyy]

@@ebaraexpress7260 Oh i forgot about that video, oops.

[@winstonpx]

Why is bipolar modulation used if unipolar modulation is generally superior in performance/efficiency?

[@ebaraexpress7260]

patentimages.storage.googleapis.com/16/8c/08/82d1ed6e25c222/JP2006197798A.pdf
P. 6 Lines 12-17
"However, the previously known unipolar modulation method cannot achieve a voltage pulse smaller than the minimum output pulse width determined by the minimum on-time of the switching device in the region where the inverter frequency is low and minute output voltage control is required (near the starting point of the VVVF control region), As shown by the dashed line in Figure 2, a voltage larger than the command will be output."
In order to resolve this problem, dipolar modulation has been applied for 3-level inverters.

[@winstonpx]

@@ebaraexpress7260 Oh I see, so when the train is just starting to move dipolar is used because a low voltage cannot be achieved with unipolar, then it switches to unipolar after more voltage is needed due to efficiency 👍