- As the enthusiast EV market matures, we're seeing cars such as this Palatov we've
got here, producing up to 1300 horsepower using three electric motors in a four wheel
drive configuration.
Now obviously with the ability to have instant delivery of torque and instant control over
that torque, there's a lot of advantages with EV, over an internal combustion engine
but as the enthusiast market develops, we need some options to control these
electric motors.
We're here with John from AEM to talk about their recently released electric vehicle
control systems.
So, John, when you've come from a gasoline tuning background, that's what I've sort of
learned, the EV world for me is a whole new world, a whole lot of new knowledge to
understand but again we've started with some production electric vehicles, obviously Tesla
jumps to mind here.
Now we're starting to see the ability to purchase either crashed electric vehicles and
use the electric motors and repowers or aftermarket options such as the Cascadia
used in the Palatov.
But controlling. this is the problem so how have AEM focused on that and dealt with that
problem?
- Well yeah the problem is real because you've got the ability to have huge amounts of power
and the power is available instantly.
If you have too much power and it's too instant, that actually is a problem, it's not really
helpful so we've created the VCU, the vehicle control units, and we've released those just now
and the whole point behind these units is to make the power delivery configurable and
manageable so that you can get optimum acceleration from the vehicle, optimum
usage from the battery and basically just take all of the things that you've put into
your EV and make them all work together and make them work together well.
- So the idea behind this is that it will be able to be used by a home enthusiast
to essentially incorporate electric motor technology and battery control into just
about any platform they want to include that in?
- Yeah correct.
The best way to think of it is, all the gas people, and I'm a gas person myself,
the gas people think about a programmable engine management system, programmable
EFI, it's essentially exactly the same thing as a programmable EFI system except it's
a programmable system for an EV rather than for an EFI.
So you still have the laptop, or the PC based control tuning, you have the tables you set
up, everything that you do, except it's all related to what you would encounter in
an EV so you do things like the cooling sections for the EV, you do things like
the battery management systems, you do things like the chargers, these are all things
that are on the vehicle, they're all things that have to be maintained in a proper
form to get the most power out of the car to get the most power available
out of the battery.
Those things are all configurable and if you use a programmable device like the VCUs,
you can set everything up so that you get the best possible configuration to get the most
performance and you can also tweak the operating parameters so that it works well
in a motorsports environment rather than a production car environment which are
just basically different assumptions on how the thing is going to be used.
- Now I think it's also important just to mention the sort of components that go
into running an electric motor so we have the electric motor itself but the VCU that you've
developed, that doesn't interface directly with the electric motor so there's an inverter that
essentially is the control strategy or control unit that goes in between.
So can you just tell us in brief terms what that inverter does and why we need that
in the system, why we can't just directly control the electric motor using the VCU.
- Sure, I mean firstly you've got your big battery in the car but that's DC,
direct current.
The motors that are used, the high performance motors that are available now are AC or
alternating current, usually three phases of alternating current.
So you somehow need to convert this DC to alternating current and it can't just be
alternating current, it actually is very critically timed with the location of the
motor in its rotation.
So a device called an inverter is actually used and this inverter is very closely tied
to the motor itself and they really work as a package, they're really almost a symbiotic
two devices that work together.
- So we're not at a point where we can take an electric motor from one manufacturer,
an inverter from another manufacturer and piece those together and expect them to
operate perfectly?
- If you have, there are some inverters that are kind of generic and they can be programmed
to be working with other motors.
Most of the OEM inverters, if you find an OE inverter in a breaker yard,
it's made for one specific motor, you can never change that but if you have one of
the aftermarket converters that are available, they're very configurable and they can be
mated to specific motors as long as the information's available.
So there are inverters like the one we have showing here from Cascadia which is a
very versatile inverter and it works with a bunch of different motors that they have
available also.
- Alright so how do you then interface with this inverter, what sort of information are
you sending from the VCU to the inverter in terms of asking for a specific amount of
torque, how does that work, how does that interface work?
- Well one of the interesting things about EVs is they're all new platforms.
So all of the communication between them is CAN based, there is usually three or four
CAN buses on an EV now so everything is talking back and forth digitally, very fast,
and the information is available and it's freely available throughout the vehicle once
you know how to speak it.
So when the VCU is talking to the inverter, what it's really asking it is what is the
availability of torque right now with the system, what can you take temperature wise,
current wise, it talks to the battery and says what can you source right now, how much
current is available based on your conditions and then with that and with all the traction
control or torque delivery, it puts all of this together along with what the driver's asking
for and comes up with a single raw number, I want X amount of RPM out of the motor or
I want X amount of torque out of the motor and I want that right now and it will
instantly within literally milliseconds it will then give you that.
And then we sent it again every five milliseconds or even every three milliseconds,
now we want this, now we want this.
So you're in actual complete control and an instant to instant control of what kind
of power output you're going to get from the motor inverter package.
- OK so there's a bunch of stuff in there that I think we need to dig into in a little bit
more detail, again, and I'm personally still very new to EV so I'm learning as we're
going here as are a lot of our viewers I'm sure.
But the battery management there, and you've sort of just talked about the fact of how much
current can you deliver at the moment and this really comes down to how much torque
you can get out of the electric motor.
So what aspects of the batter condition are going to affect what we can achieve and how
does that change as the car is being driven?
- Well mainly once you've got the characteristics of the battery,
when the battery's made, you're going to have a standard operating condition,
this is the nominal values you're going to get out of it and the key is to try and keep it
in good shape.
The biggest problem you have with batteries, it's always the same problem and it's heat.
Sometimes it's lack of heat, sometimes it's too much heat.
Batteries can be too cold to operate, they can be too hot to operate and as soon as they
get outside of a very small well defined window, they start to be derated.
You have to start turning down the current that you're pulling from them.
So the battery management system that sits on top of the battery and actually is touching
every cell and telling you the voltages, also has a bunch of temperature sensors
all through the battery and once you start getting outside of that sweet spot for
temperature, it will start derating, it'll start telling you that now you can only get
350 amps and then when it gets a little warmer and now you can only get 320 and it starts
closing down the window and it starts closing down the performance envelope
of the car.
- That's sounding like quite a complex range of parameters that we need to keep in mind
from a tuner's perspective.
Is this something that we need to deal with through the VCU or is the battery management
unit doing that in terms of something aside from what we need to control,
doing it in the background so we don't need to worry about it, we're just asking for
maximum amount of torque that's available at a certain time, given the battery conditions?
- In the past what you would do is you would say, give me the most you could give me.
And if it was too hot, it was too hot.
The battery management system may say, hey it's this temperature but it doesn't
really do anything about it, it just tells you, this is what it is.
The VCU, one of the core features of the VCU is it's trying to look at all the individual
components and make sure they're optimised for what we're trying to do.
So the VCU gets very concerned as soon as it sees that the battery's now starting
to derate based on temperature.
So since the VCU controls the coolant pumps, controls the coolant fans for all the devices,
all the coolant loops, the VCU's job is to then come in and say, my target temperature
is this and for motorsports I want it to be this, and to make that happen.
So that's something that you can do with the VCU, a programmable motorsports VCU,
where a production car doesn't do that, a production car just tries to keep it in
sort of a window that's long range production, assuming you're going to be driving on a
freeway.
In the motorsports world, you look at it and think well they're going to be making another
couple of very hard passes so we need that, if it's going to be getting warm, we need to
actually take it to the coldest amount it can still be accessible at so that when it warms up
it still stays in the zone and we know that it's going to get hot so we run the cooling
system full bore even though it's not hot yet because we want to keep it from getting hot.
- So a bit more preemptive and obviously managing that temperature as well,
long term's going to be key to the reliability of all of those components I can assume?
- Absolutely, keeping the battery, the battery temperature is key to keeping the battery life.
If you maintain the battery temperature right in the sweet spot all the time,
that battery is going to be there for you all the time, it's going to last years.
If you disregard it and you run it hot, you run it cold, you charge it when it's cold,
I mean that's the fastest way to lose 30% of your battery capacity in six months.
- Alright so in terms of the other aspect with charging these batteries, obviously
that's critical here and we can plug the car into a power source overnight.
But regenerative braking is another aspect with EV that we see which basically,
can extend the drive time of the car.
Can you talk to us about how that's managed with the VCU, how does regenerative
braking work?
- Well the great thing about regen is it's essentially the exact same thing as driving.
The VCU doesn't particularly treat it any differently, the converter doesn't treat
it any differently.
It's just if the motor is spinning and it's generating more voltage than it's being
fed, it will actually start back feeding current.
So programming the amount of regen is actually just another number.
So you can map that out in the VCU, so you could start to say well,
the BMS will tell you, I can accept a certain amount of current, so it will
tell you what's the most you could do and then the VCU can look at that and
say under these conditions, the way the throttle is held right now,
or maybe your foot's on the brake but it's just barely touching the brake,
it may only give you just a little bit of the possible regen.
Or it sees you standing on the brakes, it's going to give you 100% of the regen
and then whatever hydraulic braking you've got as well.
And then some people like to run it with a single pedal setup where maybe the
bottom 2/3 of the pedal is acceleration and the top 1/3 is actually regen.
So when you're letting off you're actually getting braking action while you're still
on the throttle pedal and that's up to the customer to decide and it's all
configurable in the VCU.
- Alright so that really brings me into the next topic which is from a tuner's perspective,
coming from an internal combustion background, normally we're manipulating fuel,
we're optimising ignition timing, that's all out the window with EV, we're asking for
torque but can you go through the workflow for the tuner.
What's it going to look like inside this VCU and what's our main tasks going to be
when we are trying to calibrate the operation of the EV?
- Sure, it's going to be different.
And this is something that people have to kind of get their head around.
All of us started in the gasoline tuning world so we've all done it, we've all sat
in the passenger seat of a car with a laptop while they're making a pass
and making a little change, it feels a little better, feels a little worse.
You don't do that with an EV because there is no tuning with an EV.
The motor, there is a proper setting for the motor and the inverter combination
and that's not something to be tuned, it's either right or it's completely wrong.
So that's always there and it's always right.
What you do tune is some of the setup, like when we talk about the cooling,
how do we want the cooling to act, do we want the cooling to always run
max cold within the window so that you can run really long, hard pulls
and stay in your range?
Or do you want to run, maybe I want to have really aggressive regen braking,
that's just the way I like it.
All of these things that define the way the car drives, those are now things you can
tune and then of course traction control and torque mapping and torque delivery,
that's wide open now because you literally can do moment to moment torque delivery
predictions and laying out what's going to happen when you launch a car as part
of a launch control sequence.
So that's wide open now.
- Yeah I think that's something that a lot of people who don't have a knowledge on
EV will probably overlook is the instantaneous response in terms of asking for a specific
torque figure and the electric motor being able to deliver exactly that and when you're
talking about the launch strategy and in particular, traction control,
that's where with internal combustion, yes there are some pretty advanced torque
control strategies but there's always going to be a latency, you don't have that with the
electric motor.
- Absolutely, absolutely.
That's the hardest thing to get used to on an EV is that when you ask for something,
it will get it to you instantly and as fast as you think an IC engine's going to respond,
it's nothing compared to what an EV will do it.
It's actually so responsive that that becomes a problem, it is too responsive,
it doesn't have any give in it at all so that needs to be programmed out of it.
And that's one of the features that we really take seriously with the VCU
is to really slow down the way things get sent to the inverter.
Not slow it down to try and make the car less aggressive, just slow it down to make
it actually where it doesn't just blow the tyres off virtually every time you
touch the pedal.
- Look it's obviously a brave new world out there as we see more and more people
move into modifying these electric vehicles and building their own take on electric
vehicles, it's great to see an option now from AEM for an aftermarket tunable solution.
And we look forward to seeing this market develop more over the coming years
so thanks for your time there John, talking us through that system.
- You're very welcome, very welcome, thank you.
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