#244 DC Inverter AC board Outdoor Circuit Description Explained, How to Test, Troubleshoot & Repair

welcome to receive electronics friends 
today we are going to discuss about   dc inverter air conditioner inverter control board   correlate this board step by step first of all 
we will discuss compressor inverter compressor it   have instead of a normal compressor it have three 
windings one two three we can say star winding   delta winding anything every winding is it is 
three phase just only we have to understand this normal compressor it have starter 
winding running winding and we do   it takes too much starting current a normal 
compressor but dc inverter ac this is actual variable frequency drive its motor pulse dc 
voltage but three phase these voltage are controlled by any inverter section any frequency drive what is in frequency drive mosfet igbt anything mosfet igbt most of the time 
there is igbt used it is in general discussion   and frequency of this always produced by some microcontroller or anything sometimes it is standalone processor sometime it 
is microcontroller sometimes it is motor control   intelligent motor control different items it 
depends upon the designer how he is using the mcu will need power what power vcc this drive circuit 
also need vcc to generate vcc we need smps   what kind of power it will generate it depends 
upon mcu if it is 5v operated we will set 5v   if it is 3.3 volt 3.3 volt in 
between this there is igbt driver so to apply vcc we need some voltage here some igbt drivers are six volt 
operated eight volt some of them are 18 volts   in normal compressor we just apply 220 volt 
to the compressor it starts running but here   we have to change the frequency and voltage 
how it will generate a voltage we need a rectifier circuit plus pfc circuit power factor 
controller this rectifier will take 220 volt single phase line and neutral so it will generate it will apply 220 volt   this circuit will convert it low 
voltage for mcu to vcc frequency drive   even here is microcontroller processor because 
we are using it in air conditioner so it have to   if you are using in refrigerator it will the same 
if we are using an air conditioner it will sense room temperature with exhaust temperature sometime it will check pressure if there is a stuck 
in any line or anything   then it can check the compressor temperature 
oil temperature we can say and then it will   perform different functions power on command is 
injected here because it is software controlled instructions are given to this 
microcontroller if room temperature is this   you have to turn on compressor at this speed maybe 
it is taking command from in indoor indoor board   indoor unit control board when everything 
is here then maybe it will give a feedback to endor unit to display and it will monitor the 
circuit here then it will generate a feedback   command if there is error it will generate 
error it will need to run a cooling fan sometime it has relay it will direct it will 
connect 220 directly to this if it is igbt mod dc   if it have dc motor then we have igbt 
drive then we will apply this 330 volt and this processor will also drive the same 
set here and it will run the cooling fan if   it is hot and cool then it will make a drive 
to relay our switch to change hotel code   so let's start and we will see this block diagram   and we will correlate in this board if 
we are using any type of dc inverter ac the design may be different here it is using 
three capacitor maybe there is two capacitor   or one capacitor here is igbt 
in intelligent mod in one chip may be in some air conditioner you will find   six igbt modules here it has six 
modules but it is built in in one chip here is also igbt i removed it that is for 
power factor correction that was short circuit   and the neutron is in here if you go in 
backside line is connected to one fuse   the line line is connected to one 
fuse line to fuse in the second side   a fuse there is over voltage protector over 
voltage protection after that one capacitor   line inductor dual line filter here is 
our neutral line neutral is in this area and the same time neutral is connected to this 
terminal we will discuss this terminal later   now it have to pass from this inductor 
and then we receive neutral here this neutral line is going to this 
point just only we have one component   in this line from neutral this point to 
this point we have just only one component   that's it that is inductor series in 
series we have just one component so here we have capacitor inductor line is here this line will reach at this point this is line   line will reach in this point we will discuss 
what is here and now line is in this area   now line will pass from this fuse 
this sorry inductor now line is here   so our current will pass from this inductor 
this current will pass from this inductor so our current stopped here   now we have to see here it stopped at this 
component this black component it is called ptc in normal condition its resistance is 36 ohm then our positive line from this ptc will reach 
here what is that that is an other inductor now we got ac 220 volt started from here and reached here 
what is here here is a bridge rectifier bridge rectifier now very interesting story is going to start here ac is here it is giving positive here is giving negative 
this end is positive this end is negative the   negative line is connected through a jumper 
resistor through a power resistor it is working as   a fuse resistor in case of any short circuit any 
over temperature sorry not over temperature any   over current condition there is a resistor inside 
it is jumper resistor two resistors one and two   we will see one by one what is their 
function this end of the bridge rectifier   is negative terminal and this 
voltage reached at this igbt   here is igbt we will discuss why this 
component is here and what's its function now   the voltage will pass from this resistor and we 
will get this voltage at one two three capacitors   this terminal needs one end of every capacitor 
needs negative the second should be positive so   we have to see the positive for positive terminal 
if we look at the bridge this cut mark this end is angle and here is a cut this 90 angle 90 degree 
angle and here is a cut so cut mark is positive   so we have to see the positive   so here it is positive so positively 
line is starting here this dotted line and positive line stopped here 
so we have to see what is there here is written a reactor reactor what is reactor reactor is a piece 
of coil it is in transformer shaped   it is about 16 ampere it can the wire 
can take it is very big gauge so it will reactor it is big big size about   three inch by three inch by three inch and it have 
just only one one wire inside that is a in core   and now we have to see the board condition if we 
look here i hope so we can look it clearly so here   it is reactor so reactor one end is connected 
here the second and end is connected here here is reactor so reactor is connected between 
capacitor positive terminal and this point   between these two points this point and this 
point so we will take we can say it is working   as a jumper but it is not a jumper it have a very 
special function it's very very special feature   we have to see it so from 
here to here we have reactor if you look here it is connected to this point so reactor is connected from this point to 
this point from here to here then other thing so reactor reached at the collector it reached at the collector of igbt and now so our voltage reached at this point 
reached at this point and then there is   a diode power rectifier short key power 
rectifier here that is forward biased diode so we will receive this voltage 
at rectifier and this rectifier the cathode side of this power it is transistor 
shaped it is igbt shaped but it is not igbt   it is power rectifier it is high current rectifier so in the output of this rectifier we have one two three we have three capacitor in parallel now we will discuss the function of these 
two components igbt reactor and rectifier   so we have to do some correction this line 
this pin of igbt is connected to ground line   this pin of igbt is connected to 
ground line so this pin is igbt base   igpt drive pin we will discuss function 
of this igbt reactor and rectifier we have positive 300 volt and we we said these are passing through this rectifier so these voltage are going to 
one capacitor second capacitor   third capacitor and these capacitors are 
in parallel and here we have one reactor 330 volt here and here we said at this point we have a rectifier sorry igbt say we are taking 300 volt   when there is no signal at the base there 
is no drive pulse it will do nothing the voltage coming from bridge rectifier 
will pass directly to these capacitors now when because the compressor and drive 
fan motors and everything takes too much load   and it will cause to decrease the voltage 
level here or maybe the input that is not   220 volt that is we can say 180 volt if 180 at 
that time this voltage will go to 280 volt suppose   because the same time the voltage will drop 
input voltage multiplied by 4 1.414 that voltage   level will here so at that time this igbt is 
working as a voltage booster it will take pulses the first function it will regulate 
the voltage it will make power factor   correction the second function of this 
device to adjust the voltage in running mode   why it have to adjust the voltage and make power 
factor correction when it will make a switching   what will cause it will cause to induce voltage 
induced magnetic field is in this inductor   when the pulse will off this magnetic field 
will collapse when it will collapse it will   induce voltage in the coil again this 
inductor so this reactor will generate   a voltage in series of the voltage coming from the 
bridge rectifier and this pulse will be rectified   and it will compensate the loading effect the 
processor will send pulses and these pulses will   cause to make a parallel path because here we have 
positive and negative and it will make a search   when it will make a surge in 
parallel because here is load   it is in parallel search so it will cause to 
induce magnetic field when the pulse was off   this magnetic field will induce voltage counter 
emf reverse emf in this reactor so this reactor   will boost the voltage level and that voltage 
level that pulses will rectified and we will take   maintained or regulated voltage level at 
these capacitors for a ripple removing small capacitors these are used to remove 
the noise i am not going to discuss   the noises and everything we can say 300 volt regulated here in standby mark this voltage will 290 volt to 330 
volts but in inverter mod it will running much   it will adjust the voltage from 210 volt 
to 300 volts and 300 volt we will get here   now we have to discuss something very special   we received voltage at these capacitors now what 
will happen here is a power link at this point   connector number 14 that is p conductor 
number 14 p and it is connected to collector number 15 p so this line is 
coming here we have to install jumper   that's a short link from here to here so positive 
voltage will applied here at this igbt module   this positive pin of this igbt this pin 
is positive the negative side of this line   is connected to this resistor 
so negative line here   this resistor is giving 
voltage to this igb igbt module so black line is here at 
this point and this end is   ground line and positive voltage 
these positive voltage will jump   from this connector here is positive 
connector to here so here is positive line positive voltage here negative here positive what is here here is scm 1240   high voltage high current three phase 
motor driver this is intelligent module if you you have six igbts here in one package the 
same six igbt are here one two three four five six   because it is intelligent it have to monitor 
the currents and everything it have to   check everything it have half bridge 
circuit consists of pre driver circuit 10 ampere to 30 ampere output of small footprint 10 ampere to 30 ampere so it is high power high 
current cmos compatible input and different things   we are not going in too much detail 
just only i am sharing the data sheet so we have to see here here the inputs are applied high and low and common high input h in for 
every phase high input low input common phase one   high input low input common phase three high input 
low input common vo3 if co2 po3 everything is here so it need a controller that will generate high 
frequency or variable frequency and it will   drive through a line driver and it will give the 
voltage switching voltage to this these pins high   drive low drive so here it have built in high fft 
low fvt at 31 pin it takes positive voltage and   at this pin it receives negative voltage the 
capacitors as we discussed there is a one resistor   series resistor and it will apply voltage to every 
low side mosfet low side igbt low sight so every   low side igbt will take voltage ground voltage 
from here and pin number 31 will have positive   voltage so here is pin number 31 it is taking 
positive voltage from here which we discussed   that a jumper is installed from this point to this 
point so we will apply a jumper and we will check   the ground line is here at this pin and if we 
look here here we have three ics for every phase every phase it have high and low driver one two three so high and low drive from this this ic 
for this phase and this ic for this phase and this ic for this phase so 
we have one two three three ics   and the same time portion of this 
drive is also driving the igbt when it have to regulate the voltage 
the igbt drive pin this pin will take   command from this this resistor 
here is the smd resistor inside so this smd resistor will take command through 
processor from where the commands are coming   i will show you yes all the command commands 
are coming from here we discussed we have a   frequency drive what is frequency drive that 
is this ic this ic is frequency drive it is a   suture stage switching stays working 
functional block diagram is here it is scm1240m this ic so   and we have driver stage the driver stage is 
here this small ics ir driver ics one two three it takes vcc to drive this driver 
section 123 we need mcu microcontroller this microcontroller ic irmck 311 it is 8051 based it have 8051 processor when we use it is complete motor drive three 
phase motor drive three phase generator this ic this small chip it is complete 
processor it is used to generate signals for three phase motors for switching 
these r drives here are going to these ics from here it has given because 
it the these tracks are very   small so we are giving commands it is 
generating commands from here yes it's more   visible from here so it is generating commands 
to these ics here it have serial eproms because this chip it needs source code k 311 it is using serial econ it is using serial eprom plus eprom that is memory 
that is two wire serial eprom that is 24 lc08 what is that that is 8 pin ic serial pin ic and 
here it it is facility to connect   with the computer if you want read write program 
it is directly communicating here with this one and then it have its test connector here if we send data and read back data after 
processing so computer will connect it here   three one one test connector so this test 
connector will communicate with this one it have   its own clock generator so it will generate comma 
clock and it will read the data and when it have   to turn on how it will work it will accept the 
commands from this computer from this processor   when processor will find every everything 
is correct input voltage are connect   correct room temperature is low 
exhaust temperature is within limit the compressor temperature is 
good at that time and we need   to cool down the temperature and we want 
to turn on the processor at which rate   the processor will define and it will send a 
command to this processor to adjust the frequency   slow running fast running so it will generate 
it will make a sequence between the phases   and we will receive its command signals every 
phase high and low drive we have three phases   so it will generate six lines and it will 
ensure the phase combination at exact sequence   so everything will flow in this way and 
our compressor is connected between this   three terminals blue that's called uv w 
uvw blue wire is here red wire is here   and black wire is here w then we need to 
power power it on because this is power stage as we discussed to power it on and 
to power this system we need a smps   switch mode power supply so switchboard 
power supply section is here this is our this small 
transformer voltage regulators lm3 17117217 adjustable voltage regulators for these chips first it will take 330 volt 300 volt from 
main capacitor through this resistor and   it will here it is power controller smps 
controller so smps controller will apply voltage   generate two voltage here two types this smps 
transformer this smps circuit will generate 17   volt approximately and 12 volt and these voltage 
are regulated in 5 volt and 12 volt further these   voltage are regulated for 3.3 volt from here 
and we will get this voltage on this capacitor so our power supply this standard alone power supply will generate   plus 15 volt plus 12 volt and other power supplies 
whatsoever so first of all we have to check   if the board is not working we have to check the 
voltage at these points ground 15 volt ground 5   volt if you don't have voltage here here is 3.3 
volt sorry 3.3 volt regulators regulator is here   and we will find this 3.3 volt from 
here from this point here is 1.8 volt 1.8 volt and 3.3 volt all voltage are mentioned on this board so these power supplies are necessary 
here we must have 15 volt after regulation   if the regulator is working 
good this regulator is good   we have to find 15 volt and then we 
must find 5 volt here at this point this 5 volt 15 volt 3.34 volt 1.8 volt 1.8 1.8 3.3 if these voltage are available then 
this work and these chips will start working now we discussed snps 3.3 volt 1.8 volt so these voltage must 
be available i will not go in   very detail how it is working so just only we have to check if any power supply is not good   we have to ensure proper functioning 
of the smps then move to this area now as we discussed when we turn on the 
compressor the compressor will run it will generate heat and we have to turn on the blower for cooling this   we need cooling fan so here is an other 
sorry this number i it's wrong it is scm one two four zero m   this i see i'm sorry for mistake then we have here 
and other igbt driver what is there it is here its function is approximately the same it is low current three ampere it have three 
phases one two three the same it takes voltage the positive voltage positive 
voltage from here and it takes ground so it will generate three phases for our 
blower motor this one so it is using stk 5 c 4 u332 it is the same same this ic same this igbt 
module and it's also intelligent power module   so it will take similar to that one it will take command from the controller and it have the same 
drive one two three these are outputs   and it have positive side and low side neutral 
and positive side v positive and neutral   and here it takes high side drive one high side 
drive two it is its controller the controller is   inside the sequence controller is inside and it 
will take high input one low input one high input   two low input 2 high input 1 high high input 3 low 
input 3 so all inputs will fed to here and it will   sample pre amplifier and it amplify and then we 
will take the final output from these points one   two three so three phases because it is also speed 
controlled for energy saving so here is dc fan now our this portion cleared in this board 
we have an other microcontroller this mcu   it is motor controller this mcu for 
motor control for checking these inputs   checking all these parameters and communicating 
within indoor unit performing other functions we   have another microcontroller here 
here is another processor these   all parameters these all 
parameters are controlled by a nce processor that is d79 f8513 a and this processor also using 24 lc08 eeprom this eprom and this is processor this processor will monitor all the 
requirements and it will control all   the functions of this board where is 
that processor that processor is here here it is programming clip self-test 
pins disconnected and this connector this programming clip for connecting with this eprom to test the function of this 
processor these are the test connectors and exhaust temperature room temperature all since 
sense lines are connected to this processor   what is the room temperature it will sense the 
room temperature and it will connect with it will   communicate with this ic and this ic compress this 
ic will start the compressor if the temperature   is increasing it will spin up the blower 
motor and the meanwhile here it have uln2003 it is uln2003 that is transistor array 
darlington transistor array that is used to   switch different devices uln2003 it takes communication it takes command from 
the processor then it connects ground with out   number one every line is it is we can say deadline 
dot linkedin amplifier it is working as a switch   so all the inputs are connected to output 
if i need to operate a relay suppose plus 5 volt or plus 12 volt what will 
happen this pin i connected to ground   then i will give a signal here at input number one 
processor signal because processor cannot drive   a relay so it is working as amplifier so it 
will switch pin number one pin number one   it will apply ground to this pin and relay 
will activate activate and we will take some   necessary function from this one here is uln003 
if we see this track is output side and this   track is connected to this relay the same time 
there is one other track that is hidden here   this pin this pin will connect to this relay these 
are relays what is the function of these relays these control the four-way wall four we've always collected here at 
these two points so these two points from this line we told if this relay will operate it 
will rotate the solenoid four-way wall solenoid   at the same time if the compressor temperature 
internal temperature is down at that time   this processor will give command to 
this relay and it will connect 220 volt   to compressor heater so it will heat up the 
compressor to build the proper pressure of the gas   for proper comfort compression we need 220 
volt to connect with the compressor heater   when the temperature will maintain it will 
disconnect a command and it will turn off dc fan reactor this is earthing line here is 
our this connector is reserved sphere for more   modifications so here are i hope so here we 
have optocouplers for feedback one two one   two three four to collect different sensors and 
different inputs here another result connector   it is for 12v pulsed pmv friends if 
this video is good for you if it is   helpful for you to understand the 
function just remember me in your prayers because this time it was 
this board was under repair this board does not have the smps ic so many 
components are removed igbt is missing so   we can take a look on this board how it is 
powering up but we don't have smps this time   so i cannot power it on because when i will apply 
power we must have vcc and these power supplies   i hope so if i bypass this power supply 
then i will try to power it on here and   if then it will very helpful to understand the 
function of this board so friends as i discussed this circuit does not have pwm controller 
because its pwm ic is burned out and it   has some problem in this area optocoupler is 
missing so what i did to show you the function i bypassed this smps this sfps external power supply this is for 
satellite receiver i connected this power supply   and i will show you the connection 
when it is connected we make a jumper   this positive voltage to this igbt module 
and from this point to this point there is a reactor from this point to this point and we need 
igbt but igbt we don't have so this time because   we are not going to run the compressor so without 
igbt we will turn on this module i will connect   jumper i collected jumper from in place of the 
reactor so we will directly take 300 plus volt   at these capacitors okay and how i collected 
this power supply it have no isolation so   never take a risk if you have not if you don't 
have a good experience in electronics never   do this practice i got 22 volts from this 
power supply and 12 volt to this possible   as our this smps gives us 12 volt and 15 volt 
at this point 12 volt is regulated into 5 volt   and 17 volt is regulated into 15 volt so 
i connected 22 volt here instead of 17   now i will connect power because this 
external power this will take 220 volt   and i made common ground for the 
board with both power supplies now at this point we must find ac 
voltage set multimeter to ac at these points input terminal i am taking 
231 volts after passing this complete circuit at the input of bridge rectifier we will find 321 volt output of the 
that is 330 volt and this 330 volt i made a jumper from this point to this 
point and this voltage from this point   to this resistor jumper resistor we will take 
this voltage here 329 volts if this 329 volt is   not available that means our bridge may be problem 
rejective fire problem ptc problem fuse have some   issue so our this line must be in this shape so 
we should find voltage in this way when these   voltage are available same time these voltage 
must be available at the bridge sorry this module   332 volt if we have this igbt module here at 
this point this igbt will regulate it at 300 volt when it will power on so in this point we must take 5 
volts here 12 volt but this time as i have external 12 volt this 
12 volt okay and we should find   this 3.3 volts must be available available 
at this capacitor this 3.3 volt for processor   1.8 volt it is available this is 
what this voltage 1.8 volt for eprom   if we don't have this voltage that 
time our circuit will not work 15 volt   available so when all power supplies are 
okay this circuit must work but this time it have some opto couplers missing so we powered on i bypassed this external power 
supply so i hope so this video is good for you   because this time we did not collected the sensors 
and everything and we cannot complete the test   moreover i told you for the power supplies how it 
is working so thanks for watching if you want to subscribe it is up to you if you want to like 
it's up to you thanks for watching and if it is   video if this video is some informative 
for you you can share with your friends thanks for watching


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