Apologies, regarding the Type 2's braking data, the correct switching timing for 1P → multi-pulse is at 9:46. Type 2の減速時における1P→同期多パルスの切替タイミングは正しくは9:46になります、ご承知おきください。
Fantastic video as always! This is perhaps going to sound silly but I've been having issues recording certain stock while accelerating due to transient noises like those that can be heard starting around 0:18 and I was curious if you had any info or theories as to what is causing those noises?
Thank you! That kind of noise might be caused by contact between wheels and a rail, or if that train is running in a third rail section, then that should be caused by the rubbing between the contact shoe and the conductor rail.
Maybe that is because you see lines around 2700Hz and 3300 Hz, but they are from input AC side (there was a bold line around 3000 Hz so I reduced by a notch filter, however these edge components are still remaining here) and not from the inverter. Also, if that kind of modulation you mentioned is applied, there should be components for 750 Hz and 1250 Hz, but not visible here. Moreover, Mitsubishi hadn't used that kind of modulation until late 2000s. Therefore, I think this is 500 Hz with 70 % dipolar rate.
@@ebaraexpress7260 The pulses in the waveform (not the spectrum) seems to be equally spaced, but the pulses in the twice frequency bipolar mode occur in pairs, so it is suspected to be a 250Hz quadruple dipolar mode.
@@CR400AF-B When determining a PWM mode, we rely more on the spectrum than on the waveform. Since we cannot remove noise components from the displayed waveform results, it is difficult to judge the mode. Also, there are some cases that inductor recorded data is more like a phase current than line-to-line voltage, which causes confusion for judging the mode; on the other hand by spectrum we can judge from both phase current and line-to-line voltage, since they are showing similar results: yuppi5.hateblo.jp/entry/pwm2 So, for this case, since I give more weight to the fact that there is no 750 Hz and 1250 Hz spectrum shown, let me conclude this as 500 Hz. Anyway I'm so interested in the way you guessed.
@@ebaraexpress7260 Your analysis is reasonable. From the spectrum, it looks more like the E2 series, and 500Hz is also a reasonable switching frequency for 3300V IGBT devices during motor start-up. Indeed, when doing moharadio on many China high-speed trains, the superposition of multiphase currents and noise makes it difficult for me to see the waveform clearly.
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Apologies, regarding the Type 2's braking data, the correct switching timing for 1P → multi-pulse is at 9:46.
Type 2の減速時における1P→同期多パルスの切替タイミングは正しくは9:46になります、ご承知おきください。
Fantastic video as always! This is perhaps going to sound silly but I've been having issues recording certain stock while accelerating due to transient noises like those that can be heard starting around 0:18 and I was curious if you had any info or theories as to what is causing those noises?
Thank you! That kind of noise might be caused by contact between wheels and a rail, or if that train is running in a third rail section, then that should be caused by the rubbing between the contact shoe and the conductor rail.
やっぱ最初のは急上昇タイプだったんですね。同期モードが聞こえにくいから1Pオンリーかと思いきや…。
Type2っぽいのはC編成でよく見かけましたね〜
The waveform of the dipolar part in type 1 looks more like 250Hz and 50% dipolar rate (quadruple).
Maybe that is because you see lines around 2700Hz and 3300 Hz, but they are from input AC side (there was a bold line around 3000 Hz so I reduced by a notch filter, however these edge components are still remaining here) and not from the inverter.
Also, if that kind of modulation you mentioned is applied, there should be components for 750 Hz and 1250 Hz, but not visible here. Moreover, Mitsubishi hadn't used that kind of modulation until late 2000s. Therefore, I think this is 500 Hz with 70 % dipolar rate.
@@ebaraexpress7260 The pulses in the waveform (not the spectrum) seems to be equally spaced, but the pulses in the twice frequency bipolar mode occur in pairs, so it is suspected to be a 250Hz quadruple dipolar mode.
@@CR400AF-B When determining a PWM mode, we rely more on the spectrum than on the waveform.
Since we cannot remove noise components from the displayed waveform results, it is difficult to judge the mode. Also, there are some cases that inductor recorded data is more like a phase current than line-to-line voltage, which causes confusion for judging the mode; on the other hand by spectrum we can judge from both phase current and line-to-line voltage, since they are showing similar results: yuppi5.hateblo.jp/entry/pwm2
So, for this case, since I give more weight to the fact that there is no 750 Hz and 1250 Hz spectrum shown, let me conclude this as 500 Hz.
Anyway I'm so interested in the way you guessed.
@@ebaraexpress7260 Your analysis is reasonable. From the spectrum, it looks more like the E2 series, and 500Hz is also a reasonable switching frequency for 3300V IGBT devices during motor start-up. Indeed, when doing moharadio on many China high-speed trains, the superposition of multiphase currents and noise makes it difficult for me to see the waveform clearly.
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