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Old 7th November 2020, 12:30   #1
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Default Explained! How Maruti's SHVS System Works

Quote:
Originally Posted by MadTiger View Post
This is some serious tech, no matter how mild it might be but its functional and it works! Thank you! I have a follow up question.

I have heard in one of the car reviews that when the engine auto start / stop kicks in while stopped at a stop light for prolonged time the ISG runs the AC compressor without starting the engine when cabin temperature increases? Is that true?
Quote:
Originally Posted by Leoshashi View Post
I'll make a detailed post on the functioning of Smart Hybrid soon. A lot of wrong info has been circulated in the media by these self proclaimed experts.
As promised, here I am with a detailed description of the Smart Hybrid system. There is a lot of nonsense and misinformation circulated in the media. Have a look at this video:



The Presenter talks about something being mounted on Flywheel and what not!

Even our official review couldn't escape from the misinformation. Two excerpts from our official review of Ciaz and Ertiga. Knowing how TeamBHP reviews work, I'm sure the origin of this misinformation is presentation by Maruti during media drives itself.

Quote:
Originally Posted by Aditya View Post
Driving the 1.5L Petrol MT
Smart Hybrid system:

The ISG replaces both, the conventional starter and alternator.
Quote:
Originally Posted by blackwasp View Post
Driving the 1.5L Petrol MT
Smart Hybrid System:

The ISG replaces both, the conventional starter and alternator.
What's true:

-Conventional Starter motor is very much present.

Explained! How Maruti's SHVS System Works-img20200713wa0081.jpg

-In simple words, ISG is a device which has dual function-Motoring as well as Generation. It's belt driven and connected to Pulley which is in turn connected to crankshaft.

Explained! How Maruti's SHVS System Works-20200718_105334.jpg

-Starting- To simplify, when push button start is pressed, the usual cranking sound can be heard, and that's when Conventional starter motor is at work. When car shuts down automatically by Auto Stop function, it resumes silently, and that's when ISG revives the engine using its belt drive. This is why it resumes silently without making any noise.

Techincal Elaboration

Description of SHVS System

The SHVS system comprises the ISG, ECM and a variety of sensors, etc. In addition to a deceleration energy regenerating function (1) that utilizes the ISG to generate power mainly during deceleration, the SHVS system is equipped with an engine power assist function (2) that acts as an auxiliary power source for the engine when the accelerator is depressed, and a starter motor function (3) used when automatically restarting the engine.

The ECM controls electricity generation based on information received from the electric load current sensor & battery temperature sensor, regardless of the activation status of deceleration energy regenerating function, in order to maintain optimum battery condition.

Explained! How Maruti's SHVS System Works-1.jpg

SHVS System Communication: ISG incorporating CAN driver communicates with ECM via CAN communication. ISG is monitoring sensors incorporated in ISG and, when detecting any abnormality, the information is transmitted to ECM and ECM performs a control to enter the fail-safe mode according to the level of the abnormality.

ISG Mechanical Operation: In the same manner as a conventional generator, the ISG (1) is connected with the crankshaft pulley (2) via the ISG drive belt (3). The ISG, instead of starting motor, enables the engine to restart and, through this, improved quietness when automatically restarting the engine is achieved. Drive belt auto tensioner (4) is adopted to stabilize the belt tension and restrict the slippage corresponding to large driving force when ISG is power assist mode.

Explained! How Maruti's SHVS System Works-2.jpg

ISG Operation:

1. Engine power assist and starter motor functions
When ISG operates as starter motor or in the engine power assist mode, the power circuit transistors are turned ON, and direct current from the battery (lead-acid battery) or auxiliary power module (lithium-ion battery) is converted into three-phase (six-phase) alternating current passing through each transistor side of the power circuit. Three-phase (six-phase) alternating current passes through the three phase (six-phase) winding of the stator to generate torque in the rotor and causing rotation as a motor.

Explained! How Maruti's SHVS System Works-3.jpg

2. Generating and deceleration energy regenerating functions: In the same manner as a conventional generator, passing current through the rotor field coil causes the rotor poles to be magnetized, and electromagnetic induction alters the magnetic field of the stator to generate electricity. The electricity generated in the stator is three-phase (six-phase) alternating current, and when it passes through the power circuit in ISG, it is rectified into direct current to charge the battery (lead-acid battery) and auxiliary power module(lithium-ion battery).

In this generating mode, the power circuit switches the transistors to ON during rectification, and the electricity generated by the stator passes through each transistor side to perform synchronous rectification.

Explained! How Maruti's SHVS System Works-3a.jpg

Description of SHVS System Components: The SHVS system consists of the following components-

ECM: ECM transmits ISG control request signal via CAN corresponding to the condition of the vehicle.

ISG: ISG is fitted in the same position with conventional generator and mainly consists of a stator coil, rotor, rotor speed sensor and inverter (control circuit, field circuit, power circuit, CAN driver, temperature sensor and field current sensor). ISG has a generator function to generate electricity and a driving function to assist engine power or to start the engine. ISG monitors all internal sensors and when any malfunction is detected, ISG transmits the information to ECM via CAN and enters the fail-safe mode.

Battery (lead-acid battery): Supplies electricity to ISG when restarting engine controlled by ENG A-STOP system.

Auxiliary power module(lithium-ion battery): Supplies electricity to ISG while assisting engine power controlled by SHVS system.

CPP No.1 switch / CPP No.2 switch (M/T model): These switches are installed on clutch pedal bracket. The switches provide ECM with information on the state of the clutch pedal.

Neutral position switch (M/T model): This switch is installed on transaxle case. ECM determines whether the gear is in neutral based on the signal from this switch.

Transmission range sensor (A/T model): This sensor is installed on transaxle case. TCM detects select lever position (P, R, N,D, 2, L)

Combination meter
- When any malfunction is detected, ECM controls ENG A-STOP warning light to blink and charge warning light to turn on. The warning lights are turned off when ECM detects normal condition.
- Status of SHVS system i.e. each of engine auto restart, power assist and deceleration energy regeneration is indicated on the information display (energy flow indicator).

Brake stroke sensor: The sensor is fitted to brake pedal, and detects the depressing degree of the brake pedal. ECM uses this information to engine auto stop control and engine auto restart control.

Description of SHVS System Control

Generating Mode: While the vehicle is decelerating, the generator generates electric power intensively to charge the lithium-ion battery
and lead-acid battery. This function is effective for improvement of fuel efficiency.
ECM (1) transmits generation control signal, ISG torque request signal and supply voltage request signal to ISG (2).
ISG controls generating torque and B terminal (3) voltage according to the request signals to charge the auxiliary power module (lithium-ion battery) (4) and battery (lead-acid battery) (5).
While the generator is working in deceleration energy regenerating mode, ECM transmits energy flow indicator signal on combination meter (6) to indicate of deceleration energy regeneration.

Explained! How Maruti's SHVS System Works-4.jpg

Engine Restart Mode: Substituting ISG for conventional starting motor, ISG rotates crankshaft through ISG drive belt and pulley to auto
restart the engine without making gear noise of starting motor. With this auto restart mode, cranking speed is raised and the following effects are brought:
Restricts engine speed to rise right after engine start.
Stabilizes and converges engine speed right after engine start.
Reduces fuel consumption accordingly.

Explained! How Maruti's SHVS System Works-5.jpg

When the conditions to execute engine auto restart are satisfied, ECM (1) transmits ISG control request signal and
ISG torque request signal to ISG (2).
ISG changes the power circuit to drive mode and the stator is energized to generate torque for restarting engine.
Turning torque of ISG rotor turns crankshaft through ISG drive belt (4) and crankshaft pulley (3).
ECM controls fuel injection to start engine.
Electric power is supplied to ISG from the battery (lead-acid battery) (5) via auxiliary power module (lithium-ion battery) (6).
While the generator is working in restart mode, ECM transmits energy flow indicator signal on combination meter(7) to indicate restarting.

Explained! How Maruti's SHVS System Works-5a.jpg

Engine Power Assist Mode: When accelerating slowly, ISG (1) assists engine power to improve fuel efficiency.
When conditions to assist engine power are satisfied, ECM (2) transmits ISG torque request signal to ISG.
ISG changes the power circuit to drive mode and the stator is energized to generate torque for assisting engine power.
Rotor turning torque of ISG assists turning of crankshaft through ISG drive belt (4) and crankshaft pulley (3).
NOTE
Engine power assist by ISG continues for maximum 30 seconds.
Power assisting torque varies according to the auxiliary power module (lithium-ion battery) (5)condition.
ECM requests relay 3P (6) to ON and electric power is supplied to ISG from auxiliary power module (lithium-ion battery).
While the generator is working in power assist mode, ECM transmits energy flow indicator signal on combination meter (7) to indicate power assist.

Explained! How Maruti's SHVS System Works-6.jpg

Conditions which Auto Start stop checks before coming into picture:

Explained! How Maruti's SHVS System Works-7.jpg

Hope this eliminates many doubts.

Regards,
Shashi

PS: Credits: Maruti's Service Manual, service circulars and training documents

Last edited by Aditya : 9th November 2020 at 14:08. Reason: Inserting attachments
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Old 7th November 2020, 12:39   #2
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Default Re: My first car: 2020 Maruti Suzuki XL6 Alpha MT Review

Quote:
Originally Posted by Leoshashi View Post
As promised, here I am with a detailed description of the Smart Hybrid system.
Whoa!

That's such an informative post. I feel even 99% of Maruti guys are not aware of this. Superb explanation like always.

The lithium ion battery is present in the petrol variants, what about diesel ones?

Mods, I feel this deserves a separate thread.
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Old 7th November 2020, 23:02   #3
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Default Re: My first car: 2020 Maruti Suzuki XL6 Alpha MT Review

Quote:
Originally Posted by Leoshashi View Post
As promised, here I am with a detailed description of the Smart Hybrid system. There is a lot of nonsense and misinformation circulated in the media. Have a look at this video:
Thank you so much! This brings in immense knowledge to nerds like me

On a more personal observation - when ever engine auto - start - stop kicks in; say at a stop light and the ambient temperature inside the cabin increases, this condition will makes the engine auto - start - stop restart the engine.

I have observed that the engine auto - start - stop keeps the engine on and will not stop automatically irrespective of the wait time. Once restarted engine will stop again only when the vehicle moves and stops. Let me know if you have observed similar observation.

Cheers!
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Old 8th November 2020, 11:44   #4
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Default Re: My first car: 2020 Maruti Suzuki XL6 Alpha MT Review

Quote:
Originally Posted by Leoshashi View Post
As promised, here I am with a detailed description of the Smart Hybrid system.
Awesome & very detailed explanation of how the smart hybrid system works , will clear many doubts. It seems the current Maruti hybrid system isn't exactly a gimmick (unlike the SHVS on the now discontinued DDiS engine), it does provide some help to the IC engine. Hopefully the next iterations of this hybrid system will be even better.

The best thing according to me here is using the ISG to restart the engine after the car is shut down by the auto stop function. I have experienced the start stop system in Mahindra cars, where the restarting process isn't at all seamless. If I were to own such a vehicle (like a Mahindra Scorpio micro hybrid), I would keep the start stop functionality permanently disabled. I ought to take a long TD of a Maruti with the current hybrid system.

P.S- I remember reading somewhere that these parts cost a bomb to replace, since they are imported from Japan. How much do they cost? (the Li-ion battery, ISG & related parts)
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Old 8th November 2020, 13:20   #5
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Default Re: My first car: 2020 Maruti Suzuki XL6 Alpha MT Review

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Originally Posted by Leoshashi View Post

Valeo supplied Made in France ISG Unit, costs around 41k at the time of compiling this review:


Primary Battery-Exide Conservo ISS N55, costs around 8.5k:


Location of 2nd Battery, visible when front seat is pushed all the way forward

Made in Japan, costs 55.5k today:
Quote:
Originally Posted by chiranjitp View Post

P.S- I remember reading somewhere that these parts cost a bomb to replace, since they are imported from Japan. How much do they cost? (the Li-ion battery, ISG & related parts)
I have included the prices that Sashi has included in this thread.
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Old 9th November 2020, 14:08   #6
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Default re: Explained! How Maruti's SHVS System Works

Maruti's SHVS System : Explained - Posts copied to a new thread.
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Old 9th November 2020, 15:11   #7
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Default Re: My first car: 2020 Maruti Suzuki XL6 Alpha MT Review

Quote:
Originally Posted by Leoshashi View Post
Hope this eliminates many doubts.
Thanks, yes, this is a usefully condensed pack of information for the Smart Hybrid system.

Some observations of my own:
Quote:
• Engine power assist by ISG continues for maximum 30 seconds.
• 30 seconds, or less if the Li-ion battery SOC drops to 2 bars. Also, downshifting seems to reduce/stop the torque assist provided by the ISG.

• The ISG does not charge the Li-ion battery when engine speed is below ~1500 rpm even when decelerating.

• ECM appears to prioritize charge to the Pb-acid battery first - only if the Pb-acid battery is at nearly 100% SOC, will the Li-ion battery be allowed to charge. With a partially discharged Pb-acid battery, the Auto Stop-Start system also does not allow the engine to shut down at traffic lights.
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Old 9th November 2020, 17:19   #8
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Default Re: Explained! How Maruti's SHVS System Works

Quote:
Originally Posted by Leoshashi View Post
Engine Restart Mode: Substituting ISG for conventional starting motor, ISG rotates crankshaft through ISG drive belt and pulley to auto
restart the engine without making gear noise of starting motor. [/b]
Thanks for the great explanation Leoshashi!

I can vouch for the smoothness of this ISG restart mechanism in the Ciaz AT - it's really quite unobtrusive and I did not feel the need to turn it off.
In contrast, the Auto-start stop is permanently turned off in my 320D because it's not a smooth experience at all.

Can you tell me why the ISG start can't be used always (or most of the time) instead of the regular starter motor in the SHVS system? I found that the ISG restarts with the Auto start-stop system were considerably smoother and quicker than the crank via the starter button.
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Old 9th November 2020, 17:49   #9
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Default Re: Explained! How Maruti's SHVS System Works

Lot of valuable insights. Can you also throw some insights on why the Lead-Acid Battery has to be replaced from a specific brand and type, otherwise the ISG function is disabled.
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Old 10th November 2020, 18:34   #10
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Default Re: Explained! How Maruti's SHVS System Works

Quote:
Originally Posted by Leoshashi View Post
As promised, here I am with a detailed description of the Smart Hybrid system..


....
Shashi sir, many thanks to you for providing this forum with such wealth of information - right from the PM2.5 Cabin Filter to the Engine Underbody protection to this wonderfully detailed explanation of the SHVS technology. This has helped me understand exactly how the Hybrid system works in our Ciaz!

I wanted to know your views about the reliability/longevity of this system (as the batteries and ISG seem to be quite expensive to replace). I do understand that it is a very well thought-out and thoroughly engineered system, but do you think the components will run trouble free for 8-10 years of daily use?

Last edited by kunalsingh : 10th November 2020 at 18:35.
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Old 11th November 2020, 10:03   #11
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Default Re: Explained! How Maruti's SHVS System Works

Crisp and to-the-point detailing @Shashi Sir. Thank you for this otherwise ignored aspect for SHVS car owners.

A question I had - off late, whenever our Ciaz glides over a pothole/speed-breaker, there's some uncomfortable sound coming in from the underbelly of the driver seat - which houses the SHVS battery (correct me on the position). The sound is more like the battery getting loosened from it's hinges and it dashes on the rails of the seat between which it is placed. This makes me nervous for a moment or so.

Are you/any Ciaz owner facing this issue? What could possible be happening?

Mine is a 2019 face lifted Manual Petrol Delta.


Regards,
Jigar Shah
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Old 11th November 2020, 10:32   #12
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Default Re: Explained! How Maruti's SHVS System Works

Thanks for sharing. I've always wondered how this system works.

Is there any real world data on fuel economy gains with this system? It will be interesting to compare data for a Ciaz with a NA 1.5l and a NA 1.5l equipped with SHVS. I guess it will be negligible cause system isn't like a Prius, where there are electric motors to propel the car. This is more of a Hybrid system, on a shoe string budget that can offer short term torque gains.

With Toyota now having a small stake in Suzuki, I guess its only a matter of time when Toyota's Hybrid system makes it to Suzuki cars. If they can manufacture this system in India, it can give Maruti a further edge when it comes to technology & economy on their cars.
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Old 11th November 2020, 15:35   #13
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Default Re: Explained! How Maruti's SHVS System Works

Quote:
Originally Posted by jigar1791@gmail View Post
Crisp and to-the-point detailing @Shashi Sir. Thank you for this otherwise ignored aspect for SHVS car owners.
=======
Regards,
Jigar Shah
The SHVS battery is below the passenger seat and no, I have not faced this issue on 2019 AT Alpha.
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Old 11th November 2020, 16:12   #14
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Default Re: Explained! How Maruti's SHVS System Works

That's highly detailed! Thanks for the post.
I do have some doubts though :-

In normal cars isn't the power generator (or whatever it is called please pardon my ignorance), also working to generate power all the time, even while de-acceleration, because even that is connected to the engine in same way?

I mean isn't true regenerative braking harnessing the wheels power to charge the battery (something which goes unused in normal cars) and also slowing down the car, since this part is not connected to the wheels at all, isn't this as good/bad as the regular generators in cars? How can this help in improving efficiency then?

Also why is there a need to put a regular starter motor if this part does the same job in a much better way?

I feel the main use for this system is in making start-stop system seamless and very useable, also providing a little torque boost in some situations, that is it. (No idea how meaningful the actual boost is), from what i understand the gains in efficiency are negligible unless i'am missing something big here.

Last edited by Rocketscience : 11th November 2020 at 16:13.
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Old 11th November 2020, 20:02   #15
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Default Re: My first car: 2020 Maruti Suzuki XL6 Alpha MT Review

Quote:
Originally Posted by SS-Traveller View Post

The ISG does not charge the Li-ion battery when engine speed is below ~1500 rpm even when decelerating.
Paid attention on this aspect today, in my case it was going well below 1500 rpm and the Li Ion battery was still being charged. Continued till approximately 1200 revs.

Managed to click this:

Explained! How Maruti's SHVS System Works-20201111_163152.jpg

Regards,
Shashi
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