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
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