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G8MNY > TECH 29.08.10 10:01l 105 Lines 4325 Bytes #999 (0) @ WW
BID : 60844_GB7CIP
Read: GUEST
Subj: DURITC 1kW 230V Inverter/UPS
Path: IZ3LSV<IK2XDE<DB0RES<ON0AR<UA6ADV<GB7CIP
Sent: 100828/2258Z @:GB7CIP.#32.GBR.EU #:60844 [Caterham] $:60844_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (Updated Mar 08)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
Not a UPS really but a high power, stepped square wave mains inverter from 12V.
It was blow up when I got hold of it it. I now have it working with new output
high voltage MOSFETS.
Having made this sort of thing before with heavy conventional transformer etc.,
I was amassed at this modern HF version, just how small & light weight it is.
DESCRIPTION
It has 5 pot core HF pulse width inverters with 2 TIP MOSFETS each handling
200W. The 5 floating secondaries are connected in series to feed a fast high
voltage bridge rectifier to a HF choke into large 400V smoothing.
ÚÄÄÄÄÄÄÄ¿ ÚÄÄÄÄÄÄÄÄÄÄÄÄ¿
LÄ´High V ÃÄÄÄÄÄ´340v HT RECTÃÄÄÄ<ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
NÄ´outputs³ HT ³ & FILTER ÃÄÄÄ<ÄÄÄ¿ ÚÄÄ¿ ÚÄÄ¿ ÚÄÄ¿ ÚÄÄ¿ ³
ÀÄÄÂÄÄÄÄÙ ÀÄÂÄÄÄÄÄÄÄÄÄÂÙ ~ ÚÁÄÄÁ¿ÚÁÄÄÁ¿ÚÁÄÄÁ¿ÚÁÄÄÁ¿ÚÁÄÄÁ¿
/³\ \³/ \³/ ³200W³³200W³³200W³³200W³³200W³
³drive I³mon V³FB ³ INV³³INV ³³INV ³³INV ³³INV ³
ÚÄÁÄÄ¿ ÚÄÄÄÁÄÄÄÄ¿ ÚÁÄÄÄÄÄ¿ ÀÂÄÄÂÙÀÂÄÄÂÙÀÂÄÄÂÙÀÂÄÄÂÙÀÂÄÄÂÙ
³50HzÃÄÄ<ÄÄ´CONTROL ÃÄ>Ä´HF PWMÃÄ>ÁÄÄ)ÄÄÁÄÄ)ÄÄÁÄÄ)ÄÄÁÄÄ)ÄÄÙ ³
³ Osc³ on ³fan ³ on³ OSC ³drive³ 30A ³ ³ ³ ³
ÀÄÄÄÄÙ ³overload³ ÀÄÄÄÄÄÄÙ |fuses| | | |
³12 V? ÃÄÄ<ÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÁÄÄÄÄÄÁÄÄÄÄÄÁÄÄÄÄÄÁ<
ÀÄÄÄÄÄÄÄÄÙ 12V @ 125A
The pulse width feedback controls that voltage to 340V. This powers 2 high
voltage MOSFET amps (blown up) that switch the L & N to +340V for 2/3 for the
time giving the 340V peak & 230V RMS 50Hz output.
OUTPUT WAVEFORM
+340V´ ÚÄÄÄ¿ Fixed Voltage
-230V³ ³ ³ Fixed pulse width
³ ³ ³
0V ´ÄÄÙ ÀÄÄ¿ ÚÄ
³ ³ ³
-230V³ ³ ³
-340V´ ÀÄÄÄÙ
The control for this lot is not simple there is monitoring of temperature,
output current, supply Volts, etc. So working without a diagrams is not easy,
still I have it going now & done some worth while modifications....
PULSE CURRENT
If a capacitive load from say a mains filter is put across the output then the
high voltage Power MOFETs can easily be blown up again, as very high pulse edge
currents can flow.
20A ´ 1kW Restive ³ 100W load
³ Load ³\ + 0.1uF
6A ´ ÚÄÄÄ¿ ³ \_ ³
0A ´ÄÄÙ ÀÄÄ¿ ÚÄ ÄÙ ³ÄÄ¿ _³Ä
-6A ´ ÀÄÄÄÙ ³ ³ /
³ ³/
-20A´ ³
MODS
1/ Added HT fuse after 340V smoothing!
2/ Added a mains IEC in socket & 3 pole changeover relay for bypass (UPS).
3/ Added standby trickle charging, up to 1A @ 13.5V regulated.
4/ Speeded up the mains fail start up time, but it is too slow for some things.
5/ Added 1uF polly across each HF inverter 12V supply rails.
6/ Added 0.1uF @ 600v across the main HT caps.
7/ Bifilar balanced wound bigger HF choke after bridge rectifier, reduced QRM.
8/ Made balanced L output filter (from old HF choke & 2x 6n8 caps to ground).
WARNING
Devices that use the reactance of mains caps to drop the mains voltage can be
destroyed on this waveform. e.g. a true RMS digital meter! As the pulse edge
puts 100x the voltage into the current limiting R or the circuit...
LÄ´ÃÄ100êÄÄÂÄÄ´>ÃÄÄÂÄ220êÄÂÄÄ 100ê will catch fire with 340V pulses into
C ÚÄ)Ä´>ÃÄÄÄ´+ _³_ it despite the 1uF looking like 3k3 @ 50Hz!
1uF ³ ³ === /_\`12V I solved this with a 330ê 5W in its place!
³ ÀÄ´<ÃÄÄÄ´100u ³
NÄÄÄÄÄÄÄÄÁÄÄÄÄ´<ÃÄÄÁÄÄÄÄÄÄÁÄÄ
FUTURE
Some day I want to make it pseudo sine wave output. This I think can be done
quite efficiently by changing the large HT Cs for low value pi filter just to
remove the HF & use a CR shaped ramp up & down @ 100Hz AC applied to the HF
inverter loop regulation.
+340V´ .Ä. 5% idle
+230V³ / \ Ý Ý
³| |
0V´Ù+45% À¿ -45%Ú
³ | |
-230V³ \ /
-340V´ `Ä'
So instead of switching a full the 340V for 30% ñ outputs (230V RMS) the switch
will switch say @ 45% ñ a ramp up & down, avoiding much of the huge peak edge
currents & associated 50Hz HF QRM.
Why don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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