Thursday , October 11 2018
Home >> Tutorials >> Ups repair tutorials >> how does homage ups works | ups kaise kaam karta hai | ups repair tutorial part 1

how does homage ups works | ups kaise kaam karta hai | ups repair tutorial part 1

hi and welcome to electronic abc ,in these days chinese made ups like homage inverex invermax are very popular because they are very cheap.these ups are very sensitive and gets damaged very quickly. most technicians are unaware about technology used in chinese ups like homage ups  they don’t know how does homage ups works and they felt in trouble. so i have planned to make a series of ups repair tutorials. this is part 1 of  ups repair tutorial  series.  and here is part 2 homage ups power supply uc3845 schematic explained part 2   In this post i will show you how does homage ups works and what steps takes homage ups before starting operation and during operation. i have selected homage ups to explain how ups works.in next post i have explained homage ups power supply uc3845 with schematic explained

homage modified sine wave ups (Uninterruptible Power Supply)
homage modified sine wave ups

how does homage ups (Uninterruptible Power Supply) works ?

so let’s start. i assume that you have a basic knowledge of what is ups and what is
purpose of ups. as you know that ups works in two modes 1 Backup Mode 2 Line Modepower switch homage hexa 1204 

Backup Mode

when power button(shown in picture above) on ups gets pressed it sends vcc voltage to ic uc3845 (on pin number 7) which is part of internal power supply of ups.

internal power supply in homage ups
internal power supply in homage ups

when internal power supply gets started it generates 12 volt at secondary of smps transformer. i have briefly explained in  Homage ups power supply UC3845 schematic diagram explained . there is a U17  78H05

U17 78H05
U17 78H05

which is 5 volt regulator . 5 volt regulator gets 12 volt and send VCC 5 volt to microcontroller.
when microcontroller gets 5 volt it boots up and checks battery voltage incase of 12 volt
ups it verify that battery voltage is between 10 volts to 15 volts incase of 24 volt
ups battery voltage is between 20 volts to 30 volts. if battery voltages are not
in range then microcontroller sends shutdown signal to power supply section and
power supply stops there operation ups goes in dead position. here is tutorial on How to troubleshoot Dead UPS .

if battery voltages are in range then microcontroller sets mode of operation
(inverter or charger) by checking status of power switch ( via U23 optocoupler)
Is it in the OFF position or ON position?.
.on U23 optocoupler pin 3 if switch is on there should be greater then 3 volts
if switch is off there should be 0 volts on U23 pin 3.if power switch is on then
Microcontroller further checks mains input voltage(220 volt) (This process continues at all times).if there is no mains
then microcontroller sets mode of operation to inverter mode and the ups will give a
single beep for 1 or 2 seconds.if there is  mains voltage then microcontroller sets mode of operation to charger mode.

push pull inverter in homage ups
push pull inverter in homage ups

in inverter mode after beep the microcontroller sends turn on signal
to sg3525 pin 10 (via U12) in inverter section . sg3525 starts oscilator if pin 10 of sg3525
is low and sends driving voltage to MOSFET’s of push pull inverter  .

 

 

 

push pull inverter output section
push pull inverter output section

push pull inverter generates high frequency 300 volts AC . 300 volts AC gets rectified via D1, D2, D3, D4. C 10 is Smoothing capacitor  used to smooth (filter) the pulsating DC output after rectification .

 

 

 

 

after enabling push pull inverter microcontroller Send 50HZ DC To AC inverter in H-bridge modeac signals to h-Bridge DC TO AC converter section. Dc to Ac inverter section converts 300 DC volts into AC volts. microcontroller turns on  output selection relay and output of DC to AC converter reaches to charging section.

There are two large MOSFET’s placed left of DC to AC converter section. charging section also regulates output of DC to AC converter. if no output voltage or output voltage goes lower then < 180 volts ac then microcontroller shows Fault 0 and beeps continuously. if  output voltage is above then 245 volts it will  shows fault 8 here is tutorial how to fix ups fault 8. if voltage are between 180 volts to 245 volts then microcontroller checks continuously battery voltage if battery voltage goes high (above 14.5 volt) fault 5 or fault code 5 appears at LCD display of homage inverter and inverter beeps continuously. 

next microcontroller checks internal fan (This process continues at all times) if internal fan is not running then microcontroller wait for 3 seconds if internal fan  does not responds then it shows fault 4 on LCD display . here is video tutorial on how to replace ups fan .

after checking fan status if fan is running then microcontroller continues operation in inverter mode until it detects mains input voltage detection or low battery detection or over load detection

  1. mains line input voltage
  2. battery voltage are in normal range
  3. out put load status( over load)
  4. ups temperature
  5. out put voltage
  6. internal Fan is running

Line Mode

Line mode has 2 Sub modes of operation

  1. charging mode
  2. Float mode

Charging Mode

homage ups charging section
homage ups charging section

Microcontroller checks mains input voltage(220 volt) (This process continues at all times).if there is mains
input voltage then microcontroller sets mode of operation to charger mode and sends turn off signal to both output selection relay and push pull inverter. next microcontroller Turns on charging section. in charger mode microcontroller continuously monitors

  1. battery voltage are in normal range
  2. internal Fan is running
  3. mains input voltage are in normal range
  4. ups temperature
  5. Battery charging current(amperes)

when battery charging current falls below 2 amperes microcontroller sets mode to Float mode

 Float Mode

in Float mode microcontroller turns off Fan .microcontroller sets charger voltage between 13.3 volt to 13.80 volts. next microcontroller Turns on charging section. in charger mode microcontroller continuously monitors

  1. battery voltage are in normal range
  2. mains input voltage are in normal range
  3. temperature

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