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julius64
Joined: 07 Dec 2006
Posts: 36
Helped: 1
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 05 Aug 2008 4:50 help with my UPS problem |
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Hi.
I try to desing a UPS with UPQC topology for non-lineal load, genering a signal with dsPIC30F4011 with modulation PWM in 40kHz, but i have a big problem with noise in output signal in my inverter mosfet when I connect my low pass filter.
My low pass filter is in output of my mosfet full bridge, to make a signal in 50 Hz, as show in this schematic. [/img]
The voltaje output is a 330 Volts, peak (or 220 Volt RMS)
Please help me if exist some error in my circuit or is missing something.
Very thank
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sunderwood
Joined: 08 Jan 2008
Posts: 64
Helped: 10
Location: US, CA
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| 11 Aug 2008 18:36 Re: help with my UPS problem |
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Looks like the bandwidth of your output filter is a little bit too high. I'd recommend increasing that 0.1uF capacitor.
Also, make sure you have some deadtime in your switching commands to prevent shoot through.
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masterleous
Joined: 01 Feb 2008
Posts: 1
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| 17 Aug 2008 15:02 help with my UPS problem |
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Hi,
It is your capacitor which is not of true value, use a minimum of 2 uf capacitor, however inductor is nominal.
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zlatkoMM
Joined: 04 Apr 2008
Posts: 158
Helped: 5
Location: Croatia
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| 06 Sep 2008 20:32 Re: help with my UPS problem |
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| I must ask --WHY is this topic allways on top?????????????????
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Audioguru
Joined: 19 Jan 2008
Posts: 519
Helped: 39
Location: Canada
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| 21 Sep 2008 18:19 Re: help with my UPS problem |
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You want to filter the output of the transformer, not its input.
The transformer needs to be a high frequency ferrite one to pass the 40kHz PWM Then the filter at the output smooths the PWM into a 50Hz sine-wave.
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Johansen
Joined: 11 Feb 2008
Posts: 35
Helped: 3
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| 21 Sep 2008 20:13 help with my UPS problem |
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only the inductor needs to be ferrite. the transformer 'sees' 50hz.
that .1 uf cap needs to be 10-30 times the value.
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fsmyth
Joined: 15 Nov 2004
Posts: 54
Helped: 1
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| 22 Sep 2008 9:19 Re: help with my UPS problem |
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Check here:
http://hmin.tripod.com/als/andysm/pages/linelvl2.html
There are a few examples of power filters; will be adding more
soon.
<als>
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Audioguru
Joined: 19 Jan 2008
Posts: 519
Helped: 39
Location: Canada
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| 22 Sep 2008 15:13 Re: help with my UPS problem |
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| Why use a huge, heavy and expensive 50Hz transformer when the circuit has 40kHz PWM?
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rauol
Joined: 02 Oct 2002
Posts: 364
Helped: 11
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| 26 Sep 2008 13:53 Re: help with my UPS problem |
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i dont think the L and C at the input of the transformer is required, the hi-frequency component will be filtered by the primary inductance of the main transformer itself, maybe only a small capacitor will be required at the output.
by the way is it a closed loop system?
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ziaulislam
Joined: 14 Dec 2007
Posts: 47
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| 07 Oct 2008 17:34 Re: help with my UPS problem |
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I THINK IT IS BATER TO FILTER HIGH
FREQUENCY AT OUT PUT IF YOU CAN’T GET SUITABLE 40K FERRITE
TRANSFORMER YOU CAN TRAY TRANSFORMER USED IN COMPUTER POWER
SUPPLY AND YOU CAN ALSO GET COMPONENTS FOR FILTER FROM
THERE.
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krish2487
Joined: 21 Oct 2008
Posts: 1
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| 21 Oct 2008 18:58 help with my UPS problem |
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hi
i am a EEE student working on a similar UPS project.
except i am working on a PIC16F series than dsPIC
can we swap info on the schematic and code ??
it will be helpful for both..
thank you..
Added after 10 minutes:
1. the switching activity of the power devices generates spikes.
2. this needs to be filtered using an appropriately calculated integrating filter.
3. In this case the capacitor Cx 0.1uf needs to be raised to 2 uf .
4.Use a appropriate type such as polyester film and foil capacitor which can withstand high peak currents.
5. Try FF06 of ALCON(india) or PPPRRB series capacitors from CTR(india)
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