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34263@N3HYM.MD.USA.NOAM BPQ6.0.18
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R:190731/1035Z @:GB7CIP.#32.GBR.EURO #:14132 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (Updated Jan 13)
(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.
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│ ┌───┐ │
│ │ ▐ │ (0) [=====] [█] │
│ │▄ ▄│ │
│ └───┘ │
─┴──────────────────────────┴─
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 cap.
┌───────┐ ┌────────────┐
L─┤High V ├─────┤340v HT RECT├───<──────────────────────────────┐
N─┤outputs│ HT │ & FILTER ├───<───┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐ │
└──┬────┘ └─┬─────────┬┘ ~ ┌┴──┴┐┌┴──┴┐┌┴──┴┐┌┴──┴┐┌┴──┴┐
/│\ \│/ \│/ │200W││200W││200W││200W││200W│
│drive I│mon V│FB │ INV││INV ││INV ││INV ││INV │
┌─┴──┐ ┌───┴────┐ ┌┴─────┐ └┬──┬┘└┬──┬┘└┬──┬┘└┬──┬┘└┬──┬┘
│50Hz├──<──┤CONTROL ├─>─┤HF PWM├─>┴──)──┴──)──┴──)──┴──)──┘ │
│ Osc│ on │fan │ on│ OSC │drive│ 30A │ │ │ │
└────┘ │overload│ └──────┘ |fuses| | | |
│12 V? ├──<─────────────┴─────┴─────┴─────┴─────┴<
└────────┘ 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 stepped waveform output.
OUTPUT WAVEFORM
+340V┤ ┌───┐ Fixed Voltage
-230V│ │ │ Fixed pulse width
│ │ │
0V ┤──┘ └──┐ ┌─
│ │ │
-230V│ │ │
-340V┤ └───┘
The control for this lot is not simple, there is monitoring of temperature, output current, supply Volts, etc. So working without the diagram is not easy. Still I have it going now, & done some worth while modifications....
PULSE CURRENT
If a capacitive load from say a good 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 │ 100W load
│ Load │\ + 0.1uF
6A ┤ ┌───┐ │ \_ │
0A ┤──┘ └──┐ ┌─ ─┘ │──┐ _│─
-6A ┤ └───┘ │ │ /
│ │/
-20A┤ │
MODS
1/ Added HT fuse after 340V Cap smoothing!
+ ┬─o-o──┬──────────┐
│ 3A FET FET L&N
340V === ├─L LOAD N─┤ 50Hz
│ FET FET Amps
- ┴──────┴──────────┘
2/ Added a mains IEC in socket small 25W mains transformer & 3 pole changeover
relay for bypass (UPS).
___________________________________________
L │ \_________
│ _______ ┌─────┐ __ ON │ L
MAINS )||(18V /\│ ┌──┴──┐ │ \_ L
INPUT )||(AC Bridge │Relay│ Start / INVERTER LOAD
)||(____│_\/ └──┬──┘ Up└──── N
│ ┴─────────┴0V │ _________ N
N____│______________________________________/
With no smoothing on the relay the relay releases quick on mains fail,
changes mains over & the inverter then starts up.
3/ Added standby trickle charging, up to 1A Max @ 13.5V regulated.
┌────┐
18V┤>├┬──────┬─┤7815├──┤>├─> +Batt
AC┤>├─┘ 470u===└──┬─┘
0V ─┴────┴────────> -Batt
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 swinging HF choke after bridge rectifier,
reduced the QRM.
_______
5x ||(_ /\
200W _│ / \ ┌──┬─────┬───── +340V
PWM ||(_ /Fast\ o│ │ │u1
INVERTERS _│ /Bridge\____(((((() === === TO
||(_ ┌Rectifier ======= │400V │ L & N
_│ │\ / (((((() │CAP │ 50Hz AMPS
||(_ │ \ / │o │ │ │
_│ │ \ / │ └──┴─────┴───── 0V
||(___│___\/ │Choke Starts
└────────────┘are in phase!
8/ Made balanced L output mains filter (from old HF choke & 2x 6n8 caps to
ground).
L───┐o ┌───────┬───── L
(((((() === Inverter
Inverter ======= Xtype ├─E O/P To
Output (((((() Caps === Relay
N───┘o └───────┴───── N
Choke Starts
are anti-phase!
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...
L─┤├─100Ω──┬──┤>├──┬─220Ω─┬── 100Ω will catch fire with 340V pulses into
C ┌─)─┤>├───┤+ _│_ it despite the 1uF looking like 3k3 @ 50Hz!
1uF │ │ === /_\`12V I solved this with a 330Ω 5W in its place!
│ └─┤<├───┤100u │
N────────┴────┤<├──┴──────┴──
Why don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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* Origin: HAMRADIO telnet lu9dce.dynu.com (21:5/101)