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Discussion Starter · #1 ·
Hey,

another questions regarding the contactor of my EV-build.
I used the Netgain Hyper9 system with the SME ACX1 inverter.
So there is the main contactor GV200QA. As soon the inverter is powered and has gone through self checks it activates the contactor.
But it makes a really "loud" humming noise as soon as activated.
I can control the pich of the noise when changing the frequency in the program, also the volume if I turn down the holding voltage. But if I turn it down to much the contactor loses connection when there are vibrations in the vehicle.
The other one (GV200MAB) I used controlled by the Orion 2 BMS doesn't make such noise.

Is it right, that the noise is normal due to the low frequency PWM given by the inverter?
Didn't hear such noise in other EV builds so wondering if this could be an issue.

Hope for your thoughts on this.
 

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Presumably the difference is in the PWM. In the Q models it's provided externally by the inverter. In the M models it's done in the contactor. I'm guessing Gigavac tuned the PWM in the M model for efficiency. Maybe worth emailing Gigavac to ask for more ideal settings?
 

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Discussion Starter · #4 ·
Thanks for the application note, will give it a try.
Also try to contact Gigavac in Germany and US (they have closed due to Thanksgiving so have to wait till next week)
 

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Just like a music box mechanism, if you have the contactor sitting on a large piece of metal, it could act as a mechanical amplifier. You may want to revise how you have your contactor mounted as another approach.

Another method is to crank the PWM up to 14kHz...that way it only drives kids nuts with the sound 😂
 

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Discussion Starter · #7 ·
Just like a music box mechanism, if you have the contactor sitting on a large piece of metal, it could act as a mechanical amplifier. You may want to revise how you have your contactor mounted as another approach.

Another method is to crank the PWM up to 14kHz...that way it only drives kids nuts with the sound 😂
Also considered that.
But that's not the case, since I mounted this one on a wood plate and I also tested it on a aluminum plate before - same noise.
So it definetely comes from the contactor itself. It's mounted properly, the bolts are tight so no vibrations or other things from that.

Tried to rise the PWM but it stops at 1000Hz. So no chance to blow the kids ears:geek:
 

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Discussion Starter · #9 ·
So today I called the German support and he refered me to the application notes. He didn't remember any case of humming contactors either and said it shouldn't be normal.
So I'm waiting for the US support to answer.

Mounting it tight couples it to the mounting plate. Does it make the same level of sound while dangling in the air?

Are you mounting it dead center on the plate?
Tried it today. So I dismounted it and tested - the noise gets quieter. So the wooden plate definately amplifies the noise but it's still there.
I made a short video to demonstrate: contactor video
 

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Seriously, try adding a capacitor. Connect it in parallel with the coil - it will absorb the pulses. Just make sure it's rated for the same (or above) voltage as the coil, and mind the polarity.
 

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Discussion Starter · #12 ·
So I got an answer from the US support today.
He said that the GV200QA is normally driven with 25kHz so people can't hear it.
With 430Hz is way too low and the sound is the contactor opening and closing at this speed.
But the maximum frequency I can put in my settings is 1kHz.
I don't know why and I also can't understand why nobody else has this problem because it's an extremly spreaded kit for electric car conversions.
Seriously, try adding a capacitor. Connect it in parallel with the coil - it will absorb the pulses. Just make sure it's rated for the same (or above) voltage as the coil, and mind the polarity.
Actually don't want to test this till I really know there's no other option to tweak this software.
But as I see there won't be another chance...
 

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I think I see what's happening.

You seem to be changing the frequency instead of the duty cycle.

You need to fire the contactor at 100% duty cycle, then back the duty cycle off a few dozen percent after a hundred or two milliseconds. The contactor SHOULD NOT be opening and closing. If it is, your duty cycle is too low in the power save portion of the cycle.
 

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I think I see what's happening.

You seem to be changing the frequency instead of the duty cycle.

You need to fire the contactor at 100% duty cycle, then back the duty cycle off a few dozen percent after a hundred or two milliseconds. The contactor SHOULD NOT be opening and closing. If it is, your duty cycle is too low in the power save portion of the cycle.
I don't think that's correct. I was going through a bunch of that stuff with a Curtis 1236 controller recently. Contactor is driven via one of the PWM outputs, where duty cycle is used to adjust the output voltage to the coil. So like my battery nominal is about 50V, contactor has a 24V coil, so duty cycle is set for 50% for basically putting half the battery voltage to the coil. Then there is the second parameter for adjusting hold voltage in a similar fashion. THEN, on top of that, all PWM outputs on Curtis have an output frequency adjustment within a certain range. Changing that parameter has no effect on the duty cycle itself, just really how that duty cycle is achieved.

Looks like the OP made up his mind though, so I will refrain from further input :D
 

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Right, needs to be between 26 and 25. 60V is good. I would try something like 1000uF. Basically needs to be big enough to maintain voltage between the pulses, but not so big that it delays your contactor significantly from opening when voltage is removed.
 

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I don't think that's correct. I was going through a bunch of that stuff with a Curtis 1236 controller recently. Contactor is driven via one of the PWM outputs, where duty cycle is used to adjust the output voltage to the coil. So like my battery nominal is about 50V, contactor has a 24V coil, so duty cycle is set for 50% for basically putting half the battery voltage to the coil. Then there is the second parameter for adjusting hold voltage in a similar fashion. THEN, on top of that, all PWM outputs on Curtis have an output frequency adjustment within a certain range. Changing that parameter has no effect on the duty cycle itself, just really how that duty cycle is achieved
Thanks for making my point....
😘

The "hold voltage parameter" is not correctly set
 

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Discussion Starter · #20 ·
These are the settings I put in the user program
This is the demo mode, so it doesn't show the voltage.
The pull in voltage is 48V and the holding voltage is 11V. That's in the application notes from GV200
Rectangle Slope Font Parallel Pattern
 
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