Repurposing Reillo Dialogvision 1500VA UPS as Inverter Using IR2153 or TL494 Driver?

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#1 21680481 10 Aug 2018 04:25

Edward Chase Edward Chase

Anonymous
Post #1
21680481 10 Aug 2018 04:25

I have two 2006 vintage Reillo Dialogvision 1500VA UPSs that have failed. Far as I can tell it’s the processor side that is faulty and not the power electronics. Am wondering if I can repurpose them as battery to mains inverters, ditching all the USB comms, battery charging, LCD display, mains synchronization, etc.

If I strip out most of the control side can I use a simple inverter driver chip such as IR2153 or TL494 to feed the MOSFETs,? Maybe with some driver transistors between, although these should be already present. Problem Is that I can occasionally mend UPSs and inverters but have never designed one so am not that skilled at this.
From attached pic you can see the switching FETS on large heatsinks at bottom centre. Bottom right is a SMPS for powering control circuits which may have to stay. Top right is transformer which only has 3 leads but think the primary and secondary share one lead. Its leads are labelled AVR which is strange. Unless it is Italian I make that Automatic Voltage Regulator. 48V battery and LCD panel on left. Control circuits are on daughterboards on their edge at right of main PCB.
Rest of main PCB is manly chokes, relays, current transformer and capacitors.

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#2 21680482 10 Aug 2018 15:36

Edward Chase Edward Chase

Anonymous

Post #2
21680482 10 Aug 2018 15:36

Found that it contains a KA3525A chip which
is similar to an IR2153 and believed same as SG3525. The circuit around it is similar to http://www.circuitsgallery.com/2014/01/sg3525-inverter-circuit-pwm.html
but more complex as it's much higher power, with parallel FETs. Also EMC complaint,
which adds chokes and capacitors. Perhaps
all I need to do is to find the enable line to the IC and turn it on. Also may need
to disconnect the synch line as that will be making sure the IC is synched with
the incoming mains, but not needed in my simple inverter.

All that saves me the difficult job of AC design.
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#3 21680483 10 Aug 2018 21:13

Elizabeth Simon Elizabeth Simon

Anonymous

Post #3
21680483 10 Aug 2018 21:13

Edward,
I think you are on the right track.I found this data sheet for the KA3525A
https://www.mouser.com/ds/2/149/KA3525A-1010657.pdfPin 10 is the /shutdown which you have to pull high to start it up.Let us know how you get on with this.
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#4 21680484 11 Aug 2018 02:15

Edward Chase Edward Chase

Anonymous

Post #4
21680484 11 Aug 2018 02:15

Thanks. Somewhat reluctant to
dive in a turn it on and cause a meltdown until I
better understated how the circuit works.I am puzzled that the 30A running
current of the FETs does not seem to carry to the big transformer on any PCB
tracks that I can find that could take that amount of current. Neither are any
of the 5 relays rated that high. So am wondering if some of the other chokes or
transformers are performing a voltage multiplication function despite them not
being very large. The only ones with wire thick enough for 30A are the inductor
second up from bottom and the medium sized (only 42mm wide) transformer at the lowest point, but with a
ferrite core does not seem suitable for 50Hz at 1500VA. It does seem to be wired
much like the transformer in http://www.circuitsgallery.com/2014/01/sg3525-inverter-circuit-pwm.html

Am now wondering if in fact this transformer runs
at kHz and charges a 300V capacitor. Then using the HV set of 4 FETs on same heatsinks as a bridge it converts that 300VDC to 230VAC. As that set appear to be controlled
off the processor and not using another KA3525 type device I think I am
against a brick wall as it will be difficult to replicate the processor’s outputs.
I suppose another KA3525 could be used but it would be challenging to get the timing
right so all 4 don’t turn on at once. Also I'd have to find a way get a feedback of the 230VAC to regulate the PWM.
#5 21680485 11 Aug 2018 03:13

Elizabeth Simon Elizabeth Simon

Anonymous

Post #5
21680485 11 Aug 2018 03:13

Edward,You might be right about the voltage being converted to 300VDC than to 230VAC. As you said, getting the timing right if the processor is dead would be difficult...
#6 21680486 11 Aug 2018 16:04

Edward Chase Edward Chase

Anonymous

Post #6
21680486 11 Aug 2018 16:04

The
2 pairs of HV FETs are run by 2 IR2104 half bridge drivers https://www.infineon.com/dgdl/ir2104.pdf?fileId=5546d462533600a4015355c7c1c31671.
Which only need a logic 1 to turn on a pair of FETS. If I have a simple circuit
that alternately enables one then the other, with a small gap in between, this should
output a modified square wave as in https://www.homepower.com/ac-output-wave-forms
. I don’t need voltage feedback in this arrangement as the KA 3525 has feedback
to ensure the 300VDC (actually 325) is stable. The FET bridge will then convert
this into a hopefully stable 230VAC irrespective of load current as the peak
voltage will always be 325V. Suspect not quite stable as these are not true
sine waves.

Can’t do a stepped
sine wave as the bridge can’t be half on, as far as I can see. But can PWM the bridge
with wider off periods when the sine wave is less high. The chokes will smooth
out the gaps. I can program PIC processors so could arrange this although it’s
a lot of work compared with an off the shelf KA3525 type device.
#7 21680487 12 Aug 2018 03:08

Edward Chase Edward Chase

Anonymous

Post #7
21680487 12 Aug 2018 03:08

This discussion has helped me investigate
the faults with the units and found that one has a failed FET. Replacing it with
a different type restores 90% of the functionality so I have ordered new FETs
and will see what that does. Even with the unit working as it is now I can put
a scope on the IR2104 half bridge and find out what waveform
is being driven.
#8 21680488 08 Jan 2019 13:18

James754 James James754 James

Anonymous

Post #8
21680488 08 Jan 2019 13:18

Great suggestion,Usually I never comment on blogs but your article is so convincing that I never stop myself to say something about it. You’re doing a great job Man,Keep it up.
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#9 21680489 09 Jan 2019 12:19

James754 James James754 James

Anonymous

Post #9
21680489 09 Jan 2019 12:19

Very valuable information, it is not at all blogs that we find this, congratulations I was looking for something like that and found it here.
#10 21680490 26 Mar 2019 12:34

Frances ytruyiy Frances ytruyiy

Anonymous

Post #10
21680490 26 Mar 2019 12:34

You might be right about the voltage being converted to 300VDC than to 230VAC. As you said, getting the timing right if the processor is dead would be difficult.
#11 21680491 27 Mar 2019 10:46

Frances ytruyiy Frances ytruyiy

Anonymous

Post #11
21680491 27 Mar 2019 10:46

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Senergy TEC Senergy TEC

Anonymous

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Topic summary

✨ The discussion centers on repurposing two vintage 2006 Reillo Dialogvision 1500VA UPS units with faulty control processors but intact power electronics, into simple battery-to-mains inverters. The original complex control circuitry, including USB communication, battery charging, LCD display, and mains synchronization, is considered for removal. The user explores using inverter driver ICs such as the IR2153 or TL494 to directly drive the MOSFETs, potentially with intermediate driver transistors, though the existing IR2104 half-bridge drivers may suffice. The UPS contains a KA3525A PWM controller chip, similar to the SG3525, which manages a high-power, EMC-compliant inverter stage with parallel MOSFETs and chokes. The user investigates the enable (/shutdown) pin on the KA3525A to activate the inverter function independently of mains synchronization. The power stage includes two pairs of high-current MOSFETs driven by IR2104 half-bridge drivers, producing a modified square wave output from a 300-325 VDC bus, which is then converted to 230 VAC. The transformer in the UPS likely operates at high frequency (kHz) rather than 50 Hz, consistent with a switched-mode power supply design. The user considers programming a PIC microcontroller to generate appropriate gate drive signals with PWM to approximate a sine wave, acknowledging limitations of the MOSFET bridge in producing stepped sine waves. Fault diagnosis revealed a failed MOSFET in one unit, and replacement restored most functionality, enabling further waveform analysis with an oscilloscope. The discussion highlights challenges in timing and waveform generation without the original processor and the potential to simplify the inverter control by leveraging existing driver ICs and power components.

FAQ

TL;DR: Converting a Reillo Dialogvision 1500 VA UPS is doable; “1500VA UPSs” already include inverter-stage hardware you can reuse. [Elektroda, Anonymous, post #21680481]

Why it matters: This FAQ helps repairers repurpose failed UPS units into stand-alone 230 VAC inverters safely and efficiently.

Quick Facts

Control IC: KA3525A (aka SG3525 family) present on the main board. [Elektroda, Anonymous, post #21680482]
DC link: Approx. 300–325 VDC before the 230 VAC H‑bridge stage. [Elektroda, Anonymous, post #21680484]
Gate driving: Two IR2104 half‑bridge drivers command four HV MOSFETs. [Elektroda, Anonymous, post #21680486]
Battery system: 48 V nominal pack; original charger/LCD can be bypassed. [Elektroda, Anonymous, post #21680481]
Field note: Replacing one failed FET restored ~90% functionality in testing. [Elektroda, Anonymous, post #21680487]

Can I repurpose this Dialogvision 1500VA UPS as a basic inverter with IR2153 or TL494?

Yes. The unit already has inverter‑grade power electronics. Builders considered replacing control with simple drivers like IR2153/TL494, while bypassing USB, charger, and LCD. Reuse the existing MOSFET stage and transformer path where practical. [Elektroda, Anonymous, post #21680481]

Where is the KA3525A enable/shutdown pin, and how do I start it?

KA3525A uses Pin 10 as /Shutdown. Pull this pin high to enable the PWM controller. Add proper dead‑time and current sensing before powering the output stage. As one contributor noted, “Pin 10 is the /shutdown.” [Elektroda, Anonymous, post #21680483]

Do I need mains synchronization for off‑grid inverter use?

No. The sync input was for utility‑tie operation. For a stand‑alone inverter, you can disable or ignore the mains sync so the PWM runs independently. This simplifies the conversion while keeping the power stage intact. [Elektroda, Anonymous, post #21680482]

What topology does this UPS likely use internally?

Evidence suggests a two‑stage design: a high‑frequency converter boosts 48 V to a ~300–325 VDC bus, then an H‑bridge makes 230 VAC. The poster flagged timing challenges if the original processor is missing. Avoid simultaneous conduction events. [Elektroda, Anonymous, post #21680484]

How are the high‑voltage MOSFETs driven, and can I make basic AC?

Two IR2104 half‑bridge drivers control the four HV MOSFETs. A simple logic circuit that alternately enables each half‑bridge, with dead‑time, produces a modified square‑wave output. As noted, they “only need a logic 1” to switch. [Elektroda, Anonymous, post #21680486]

What waveform quality should I expect after conversion?

Expect modified square‑wave unless you implement advanced PWM shaping. The IR2104/H‑bridge can be toggled for basic AC. True sine requires tighter timing and feedback, which the original processor handled. [Elektroda, Anonymous, post #21680486]

Why don’t I see 30 A PCB traces going to the ‘big’ transformer?

Because the heavy conversion appears to occur at high frequency, not 50 Hz. Current may route through smaller HF magnetics and chokes that handle the power before the 325 VDC bus feeds the H‑bridge. The 30 A observation came from tracing doubts. [Elektroda, Anonymous, post #21680484]

Is it realistic to rebuild the 230 VAC timing without the main processor?

It’s difficult. The original processor coordinates H‑bridge timing and feedback. “Getting the timing right...so all 4 don’t turn on at once” is critical. Shoot‑through will destroy FETs instantly. Consider retaining existing control where possible. [Elektroda, Anonymous, post #21680484]

How can I verify the H‑bridge is switching correctly?

Probe the IR2104 gate drive outputs with an isolated oscilloscope. Confirm alternating conduction and clean dead‑time. A user restored most functions after a FET swap and planned to scope the half‑bridge to confirm waveforms. [Elektroda, Anonymous, post #21680487]

What safety risks does the ~325 VDC bus introduce?

The DC link is lethal. Treat it as live even after power removal due to stored energy in capacitors. Use bleeders, PPE, and isolation. Build test procedures before energizing the H‑bridge. [Elektroda, Anonymous, post #21680484]

I replaced a single failed FET and most features returned—is that normal?

Yes. One report showed a different FET restored about 90% functionality before the correct parts arrived. Replace devices in matched sets where possible and re‑test with current limiting. [Elektroda, Anonymous, post #21680487]

What does the ‘AVR’ label on the transformer mean here?

It likely marks an Automatic Voltage Regulator winding or assembly within the UPS. In the teardown, the transformer was labeled “AVR,” prompting that interpretation during the repurposing discussion. [Elektroda, Anonymous, post #21680481]

What is KA3525/SG3525 in simple terms?

They are fixed‑frequency PWM controller ICs for power converters and inverters. In this UPS, the KA3525A governs the high‑power stage with feedback and drives parallel MOSFETs through downstream gate drivers. [Elektroda, Anonymous, post #21680482]

What is an IR2104 half‑bridge driver?

IR2104 is a high‑ and low‑side MOSFET gate driver. It level‑shifts logic signals to drive a half‑bridge, enabling H‑bridge AC generation when two devices are used. [Elektroda, Anonymous, post #21680486]

How‑To: Enable the KA3525A inverter stage in three steps

Identify KA3525A Pin 10 (/Shutdown) on the control board.
Pull Pin 10 high through a suitable resistor to enable PWM.
Power the logic supply and confirm switching at the gate drive stage before connecting the load. [Elektroda, Anonymous, post #21680483]