whqxe Hello, I am professor John Kelly and this is
the WeberAuto YouTube channel. Today we are going to be looking at the Honda Integrated Motor
Assist (IMA) hybrid system used in many of their vehicles since the year 2000 Honda has this
little electric motor it's a 20 horsepower 15 kilowatt electric motor that is sandwiched between
as you can see it's really thin here between the internal combustion engine and the transmission
this motor assembly and we'll learn more about it here coming up shortly has been used with as small
as a little three-cylinder engine in the original Honda Insight it's been used in four-cylinder
engines with the Civic Hybrid and the cr-z and the newer insight it has been used with a V6 engine in
the 2005 through 2007 Accords and it adds additional power to the engine by bolting this electric motor
rotor right to the crankshaft of the engine and helping it rotate with an electromagnetic field
so this is a synchronous AC motor that is used to help the crankshaft rotate as we drive down
the road there have been several revisions and improvements to this system since it came out in
the year 2000 and to my knowledge I believe the last vehicle model year that it was used in was
a 2016 for the Honda cr-z vehicle so let's take a look at the components involved with the Honda
integrated Motor Assist system and then we'll take apart some of these components we'll learn how to
remove and reinstall the electric motor rotor and stator assembly and see what's unique to the Honda
system compared to other systems that we will be looking at in future episodes and ones that we've
seen already in previous episodes so let's begin with the wire harness so right here on the table
I have the 16-foot long wire harness that we looked at in the episode on high voltage hybrid
system vehicles this is a two connection DC high voltage this connects to the battery in the trunk
on say a 2010 Toyota Prius and the other end would connect to the inverter with converter assembly
up underneath the hood so that's a 2 wire system the Honda does it differently Honda as you can
see here has a 3 wire system which means this is not DC this is a three-phase AC voltage and this
harness is just as long as this Prius one but this is the Honda integrated motor assist 3 wire cable
that runs from the inverter and converter assembly that's behind the backseat on those cars up to
the integrated motor assist motor rotor and stator assembly that sandwich between the engine and
the transmission so a very long three-phase cable this is AC voltage we're on the Toyotas it's a DC
voltage as a matter of fact Honda is the only one I'm aware of that has this big long three-phase
cable going from the back of the vehicle all the way to the front there may be some others but for
the most part it's a DC cable still high voltage just like the the Honda one but it's 3 wire
instead of 2 water alright now let's look at some other components ok the next component we want
to look at is called the intelligent power unit the IPU and this entire assembly here goes behind
the back seat on whatever honda civic hybrid or accord or CR z or insight of course the first
inside didn't have a back seat but behind the back seat of the later ones the intelligent power
unit contains the inverter assembly that takes our high voltage DC and inverts it into three-phase
AC it contains our DC to DC converter that takes our 158.4 volts on this particular model
it could be 144 on other models and steps that down to about 14.5 a half volts to charge the
low-voltage charging system on those vehicles this contains the air conditioning system driver for
the electric air conditioning compressors that sum well that all later model hybrid models had the
early civic and early insight had a belt-driven one only if he wanted air conditioning then you
would have to sacrifice the idle stop mode where the engine would shut off when you pull up to a
stop light or a stop sign ER or stop driving the vehicle on later models they had some weird belt
driven and electric AC compressors and then just pure electric air conditioning compressors
after that but this one has a driver for the electric air conditioning compressor these are
air-cooled there's these are not liquid-cooled so there's a fan built into this it pulls in air
from the speaker shelf puts it through the the whole system and then blows it out through
a vent into the trunk system where can go out the little pressure relief doors in the
side of the body so let's take a closer look at the intelligent power unit now right here in the
bottom of the intelligent power unit that hole right there is where the three-phase cables right
here would come in and connect to the inverter assembly on the front of the intelligent power
unit this entire front cover unbolts but before you on bolt that there's a warning label right
here warning high voltage you will be killed or hurt do not remove this cover no customer service
parts inside and then it has battery disposal information this 158 volt nickel metal hydride
battery requires special handling and disposal process and it gives you a phone number to call
here in the United States so the proper procedure for opening this rear cover if you needed to
change the battery which is over here or any of the inverter converter air-conditioning driver the
fan or anything else is there's a cover right here that that you take off and then there's a switch
and you'll notice there's an on and an off right there there is a safety button right there that
you have to push to turn it back on but there's a switch then we've accidentally broken the switch
off but let me flip it forward there's a little remnant of the switch right there but to shut
it off we just slide it down and to turn it back on we have to push down on the red plunger and
then slide it forward so what this does when we shut off that switch is it disconnects the high
voltage battery that is all the battery modules are in series with each other it disconnects that
series circuit inside the battery and makes it to where there's no high voltage when we take off
this cover and we should be safe but just in case we will use our personal protective equipment or
gloves safety glasses and so on to prevent damage to ourselves and any other electrical components
ok personal protective equipment we are going to put on our high voltage gloves with the cotton
liners on the inside and the leather outer gloves to protect the $65 air have pair of high-voltage
gloves from getting cut the sheet metal here has lots of razor-sharp edges and you got to be
real careful that you don't cut your skin let alone the gloves that you're going to wear I
have already tested these gloves for leaks so I'm going to skip that part of the testing procedure
I have a separate video on personal protective equipment and you can watch that by clicking on
a separate link to learn how to test these gloves to make sure they are safe
to use so I've got the outer leather gloves on to protect the inner
high voltage gloves from getting cut okay as I've done in previous videos I am
not opposed to using an electric impact gun or electric ratchet to remove things or even an
air-powered one as long as you realize there's a position between off and full throttle you
can back these out slowly and make sure that you're not bringing any threads with it also I
never use this if the bolt that it's screwing if the bolt screws into something plastic because
that plastic piece can get broken quite easily so let's remove the bolts that hold this cover
down okay our power switch is off I've got my personal protective high-voltage gloves on we can
now lift off the cover and set it off to the side okay with the cover removed we can see some of
the individual components this whole assembly right here from here over to here is the 158.4
volt nickel-metal hydride battery now this is out of a second-generation Honda Civic Hybrid
the first generation and the third generation batteries were 144 volt however the first and
second-generation batteries are nickel metal hydride the third generation battery is a lithium
ion battery now these batteries on the first and second generation had a lot of problems with
longevity durability self-discharge hybrid cars on the vehicle law with a nickel-metal hydride
battery needed to have the high voltage battery recharged every 90 days there's a service bulletin
for that for sitting because of self-discharge and the recharge procedure was you would start the
engine warm it up and then bring the engine RPM up to whatever RPM it specifies for that vehicle it
was somewhere around 3000 rpm or so on the one I read for this one and then you hold that for so
many minutes while the rotor assembly and the IMA motor stator assembly through electromagnetic
induction would recharge this battery here so there are service bulletins for battery warranty
extensions because the batteries weren't lasting as long as they should have if you have a honda
hybrid vehicle specifically the civic hybrid in the first or second generation and that
battery needs to be replaced honda has extended the warranty for some of those vehicles for a
much higher mileage and number of years beyond the original warranty so be aware I mean they're
not going to cover it for life these batteries do need to be replaced now and again but it has a
longer warranty period than it originally came with alright now as you can see right here we
have a short orange wire with a negative symbol on it and a short orange wire for the positive
symbol those two wires are the DC wires that go from the high-voltage battery here to the inverter
assembly which is down underneath this so that's 16 foot long 2 wire DC cable high voltage DC
cable that I showed you was in the 2010 Toyota Prius on the Honda Civics just this little short
thing here this the less than less than a foot long on the Toyotas the three-phase cables
that went from the inverter convertor down to the transmission transaxle were fairly short
but now the three-phase cable that goes from the inverter assembly clear up front to the electric
motor that helps the engines crankshaft rotate is the really long one so Honda basically on their
IMA system has has swapped the cables basically you've got the short DC cables instead of the
long ones you've got the long three-phase cables instead of the short ones and that's just simply
because all of this stuff the inverter converter air conditioning driver on the Toyotas is up
underneath the hood we're on the Honda's it's back behind the back seat so it makes sense that
that's that's what they've done all right now the battery has some lift out handles right here
but we can't lift it out without disconnecting it first and to disk to disconnect that even
though the power switch is off we always want to check to see if we have a voltage on that
almost cables before we put a wrench on there so I'm going to turn our multimeter to DC volts
I had a viewer here on YouTube comment that in my previous video I did not test the meter
and the meter leads to see if it even worked before I did some measurements on high voltage
systems and he's absolutely right we could have a broken meter lead internally which we've had
those over the years I told you these Fluke meters are great meters but the meter leads with
continuous use can sometimes go open so I've got a little 9-volt battery right here I am just going
to put the meter leads across that and see if we read battery voltage and I've got 9.8 volts right
there which tells me the meter leads are not open there if they're working properly and that the
meter is capable of reading a voltage so now if I go between the positive and negative terminals
here on the high voltage battery with the switch off we should have zero and we do we have we
have zero volts okay that means it's safe to unbolt those wires that also means that it's
safe to take off these high voltage gloves and use my bare skin right against in either
insulated tools or uninsulated tools if you've got the insulated ones you might as well use them
if you don't then it's safe at this point with no voltage to take those off anyway but to remove
the battery we have to take those two bolts out I have some insulated coated nut drivers here
this one's a 10 millimeter so there's one bolt – so these two wires here from the battery to the
inverter are now disconnected and I can just lay those off to the side now also right down here
there is our orange cable for our voltage sense just like we had in the episode on high-voltage
batteries this orange connector here with all these little tiny wires those little tiny wires
go in and connect to each battery module inside the battery itself and it'll tell you the voltage
on each module and you can read that on the scan tool there's one more electrical connection
right here and that is a connection between the battery condition monitor module the BCM not
to be confused with a body control module this is a battery condition monitor module but
they use BCM for short and the contactors that are and the temperature sensors that are
here on the side of the battery so now to get this battery out we just need somebody capable
of lifting out this is eighty pound battery awesome thank you, it's perfect okay as you can
see that battery module pulls out and of course this would be facing the front of the vehicle
rather than facing up as I have it here in the in the classroom now there's one more module
over here that contains all of the computers and the electric AC compressor driver the DC to
DC converter the battery condition monitor module and the inverter all of this lifts out also if
we disconnect one more electrical connector for the fan that is bolted into the bottom of
the case so now this entire assembly here get the external wire harness out of the way that
entire assembly lifts out and now we have an empty case with the exception of the intelligent
power unit fan as I mentioned before this fan is a brushless DC motor-driven fan okay I'm
going to remove the fan just has a little wire harness clip and a couple of 10 millimeter head
bolts to hold it in place this is a serviceable fan there's a service bulletin for this fan or
for the fan blades getting plugged up with lint pet hair dirt whatever it may be depending on how
dirty your interior may be or may be right at that air intake at the top of the rear speaker shelf is
where a little dog likes to rest or something and if all the pet hair gets down in there so here is
our brushless DC fan motor assembly so now we've just got this big empty intelligent power unit
housing I'm just going to set it off to the side here for a moment now let's take a look at this
this fan unit the fan blades on this unit we're very dirty and I've cleaned them really well
there's a little clip that holds the fan blade on to the armature shaft but it did not want to
come out very easily at all so if you need to clean one of these I would recommend leaving it on
the armature shaft and using something like a cotton swab or a little piece of a shop towel or
something to clean each blade so the fan would fit on here like this but I took this apart
because we are going to talk about four different types of electric motors in this series on hybrid
vehicles and this is a brushless DC motor notice we've got field coils in the middle and then
permanent magnets on the inside of this piece that hooks onto the armature shaft and now that
is just backward of the electric motor that's used here on the hybrid IMA system the
integrated Motor Assist system as they're all the permanent magnets on the rotor in the middle
facing outward and then it is surrounded on the outside by the coils of wire in the filled coils
so this is a brushless DC motor this requires a specialized controller you can see to control
which field coil to Poltz on/off to cause the fan blades to spin around with these permanent magnets
so that is a brushless DC motor alright let's look at the components that we just lifted out all the
electronic components not counting the battery here so on the front here we've got a wire harness
and this harness connects to a couple of relays it connects to the air conditioning compressor it's
the computer interface for that it connects to the DC to DC converter right here it connects down
over here to the battery condition monitor module and down underneath it connects to the inverter
assembly so now that we've got those unplugged there are two other electrical connections that
that we have here this orange connector right there is for the three-phase wiring that goes up
to the electric air-conditioning compressor and so we can unbolt this air-conditioning compressor
driver module to do that we need to disconnect the DC connection from the high-voltage battery to
both the DC to DC converter and the compressor driver so we'll just loosen those up and then
they have mounting bolts that hold these down so now we'll take off our positive DC cable just a
short little short little cable keep the bolt with it our negative cable just a little bit longer and
it's bolt and then the two DC cables through a bus bar to the electric air-conditioning compressor
driver the negative the positive terminals the negative and the positive terminals then we've
got the four mounting bolts they'll hold this down looks like my coated tool is too thick
we'll have to use the uncoated standard tools here there's a little bracket that comes
off another mounting bolt all right so now this air-conditioning compressor driver get all
the bolts I don't oh it's actually the wedged underneath the DC to DC converter with a little
ledge a little lip so we'll take off the DC to DC converter here we go so here comes the DC to DC
converter and get the bolts out of it right there here we go now on this DC to DC converter we've
got the negative and positive terminals from the high-voltage battery that connect right here and
that's the 158.4 volts down here this bolt is the 14.5 volt output to the auxilary
battery and then the bolt that holds down the housing itself is the battery negative for the 12
volt system I want you to notice this has cooling fins on the back of it because this is an
air-cooled we just looked at the fan this is an air-cooled system so unlike the Toyotas and a
lot of other hybrids that are out there that have liquid-cooled components, these are not liquid
cooled these are air-cooled so we've got to be careful not to damage these fins we want to make
sure that everything is good and clean in there not full of lint or dirt or or whatever and so
we can service this entire DC to DC converter as one part and you would probably do that if your
12-volt battery kept going dead and you didn't have any trouble codes you the system check
for the 12-volt batteries to put a turn the vehicle on but a voltmeter on your 12-volt battery
and if it doesn't read around 14 to 15 volts then your DC to DC converter is probably not working
correctly but remember it can't work correctly unless it's power feed from the high voltage
battery is good now this is a huge problem on Honda's there's even a technical service bowl and
maybe maybe it's even a recall for the battery the high voltage battery going dead that stops the
DC to DC converter from working properly that then doesn't charge the 12-volt battery and the
car could stall or die as you are driving around so that's no good so if that's happening
on your car check for service bulletins and see if the bulletin or recalls out there apply to you
now with that DC to DC converter removed we can remove the air conditioning compressor driver
assembly here oh I've just got one bolt that's stuck there we go okay so our power and ground
coming in from the high voltage battery and then a three-phase cable output notices orange this is
high Valley to the 158 or so volts to drive the electric air conditioning compressor air-cooled
also with the little cooling fins so that's our air conditioning compressor driver we can remove
the battery condition monitor module now just got a couple of nuts to hold it in place once again a
serviceable unit by the way there's been several software updates for these modules firmware
updates the battery controller update also whenever you put in a new battery these should
always make sure you've got the latest software update in it the battery condition monitor module
and any other programmable components so there's our battery condition monitor module right there
that monitors the voltages and the temperatures of the high voltage battery okay now on if we flip
this over right here on the back here we have a shield that covers the inverter assembly there's
also the capacitor module back here okay to remove the inverter and capacitor module assembly we've
got to take off this plastic cover in the front that has or that covers the DC bus bar so it's
got some plastic little Clips with a Philips head screw on them I'm just going to take those out
real quick I'm just going to unscrew those just like a screw any other screw and take them out if
they fight you coming out if they just turn and don't want to come out and put a little tension on
the back of the housing that you're taking it out of and it'll help it to unscrew and then one more
okay all right so now this cover can just lift up keep track of those little clips because they
want to go fly-in all over the place but here's the cover here's the DC bus bar the same two
orange wires that connect to the high-voltage battery that also connects to the DC to DC
converter and the air conditioning compressor driver also connect to the inverter assembly
here so now we will take off those two bolts so here's our DC busbar just has six connections
3 positive 3 negative that connect to the high voltage battery and the purpose there is
to take current from the battery for the DC to DC converter and the air conditioning
compressor driver and to take current from and put it back in the battery from the inverter
assembly here all right now we got to take this shield off and the rest of the harness
there's just some little plastic clips that hold the harness in place and then there's
a ground wire on the harness on one of the bolts that holds down this cover I can't quite
lift the cover off there are two more bolts and a shield on the other side I was hoping we
could but it won't it won't let us so if we turn this back over lift off the wire harness
release the little clips that hold it in place and we can set that off to the side let me
get those relay off of there, there we go okay so here's our wire harness we'll just
set that off to the side and then we've got two bolts right here that hold a shield in place
that covers up the connection where those three wires the big heavy orange wires from
the inverter all the way up to the integrated motor assist stator assembly where they connect
right so if we look closely here we have one two three electrical connections this is the W phase
the V phase and the U phase right there that's where our three big heavy orange cables come
in and connect so now we can lift this up the cover for the inverter comes off so now we have a
capacitor module on the top here that's held down with four bolts and then we have four bolts that
hold the inverter converter assembly down that's all one piece from Honda so if we just take out
the four outside bolts and they're a little longer than the short bolts that we've been taking out
up to this point now the inverter assembly can lift out and of course, notice it's air-cooled
also we've got our positive and negative posts from the high voltage battery right here from
and to the high voltage battery and then our three-phase cable outlet wires outlet and Inlet
so outlet as we're accelerating and driving the crankshaft of the engine Inlet as we're slowing
down and receiving power from the integrated motor assist motor assembly there in the form of
regenerative braking so we can set that off to the side right here on the top or on the DC input
side of the inverter converter assembly are two more little plastic clips once again this entire
assembly has to be replaced as one assembly from Honda but I like to take things apart as far as I
can get them without destroying anything and this does come apart one more level there's a little
plastic shield here on the front that comes off and now we can see six bolts in there
that connect three capacitors just like we saw in the inverter or the series video on
inverters and converters a couple of weeks ago there were three great big capacitors in
the first generation Toyota Prius and they had six electrical connections to them well
this is the same six electrical connections let me get those six bolts out of there and these six connect to the exact same
positive and negative DC terminals here and the purpose of those capacitors is to smooth
out they're actually called smoothing capacitors smooth out the rippling voltage from the
stator as we are decelerating and taking advantage of regenerative braking we take an AC
sine wave three of them 120 degrees apart and invert the negative portion of that flip it
over and make it positive that way it's all DC now we've got four bolts to hold the capacitor
module to the inverter so the capacitors smooth out the full-wave rectified AC voltage during
deceleration so here comes the capacitor module right here it says right on the top of it the
size of the capacitors they are 600 volts 458 micro farad's and there's three of those and then
there's a 33 micro farad and another 33 micro farad that are off to the side here in with these
little tiny wires but these three big ones here are approximately 458 micro farad's apiece so now
we can see the actual inverter assembly here if we peak down the sides here you can see there
are three distinct modules in there one for each phase of the AC voltage that is used to drive and
is used for rectification in charging the battery when you decelerate so just a quick review of what
a what an inverter assembly does we have the DC voltage from the high voltage battery DC 158.4
volts then the inverter assembly uses insulated gate bipolar transistors IGBTs to toggle that
DC and run it through the three-phase coils of the IMA motor assembly over there and it creates a
simulated sine wave three of them one for each of these modules here 120 degrees apart out of a 360
degree rotation that pulls the permanent magnet rotor assembly around and helps the crankshaft
rotate so we take DC in we create AC voltage going out three different phases of AC three
identical phases but they're just shifted in time 120 degrees and then when you decelerate we don't
use the IGBT transistors during deceleration we use the rectifier bridge there's six great big
diodes in here that when you decelerate just like an alternator on a car that has a rectifier bridge
that three-phase AC voltage is created by the IMA stator assembly over there through electromagnetic
induction is sent over here and run through this rectifier bridge that flips everything back over
to DC and then the kappa it's a bumpy DC and then the smoothing capacitors smooth it out into a
nice smooth DC that's then fed back to the high voltage battery okay so on the passenger side
of that great big intelligent power unit box that we had here one more time we've got the DC
to DC converter we've got the air conditioning system driver we've got the capacitor module
we've got the inverter assembly and we have the battery condition monitor module all one
two three four five pieces plus the electric fan it's a variable speed DC brushless fan over
there oh and we've got the DC bus bars that are the equivalent of just having more positive
and negative DC cables run to each of these components but they just do it with a heavy bus
bar instead of additional wires okay so that is who is the passenger side of the intelligent power
unit assembly now let's look at the battery side the driver's side and what what is here and what
is serviceable and what we can see in the battery
