[SRK]

I and my friends are planning to make a hybrid addon kit for scooters as our college project.
We needed some guidance and I thought T-BHP would be the perfect place for it.
1st of all I would like to tell you that we are people full of theories and we don’t have much practical knowledge, so we need your help.


CONCEPT:
Here is our concept.
The scooter that we plan to use will be a Gearless type (Kinetic, Honda activa, etc.)
We would use a DC motor to power the wheels.

The scooter would use electric powered motor to run at slow speeds or when it is at rest.
The Engine would power the wheels when the rider accelerates even after reaching the max speed of the electric motor.

Here is a basic block diagram that explains a few things that we have in our minds.


SWITCHING CIRCUIT/CONTROLLER:
This is the most important part and the one where we are facing a problem. We don’t know much about Electronics/Programming and will need some help from an expert.
Basically our requirement is as follows:
Speed sensor detects speed and sends a signal to the Switching circuit or Controller.
Conditions:
(i) At rest (0km/hr):
1. Detect speed (i.e. 0km/hr)
2. Give signal to controller.
3. Controller starts electric motor.
4. Wheels are powered by electric motor upto max speed of motor (say 20km/hr)

(ii) Above max speed of Electric motor (say 20km/hr).
1. Detect speed
2. Give signal to controller.
3. Controller Starts Engine and Engages Clutch.
4. Wheels are powered by the engine.
5. Controller switches off the electric motor.

(iii) 0-5km/hr:
1. Detect speed, if speed falls below 5km/hr or scooter comes to rest then go to step2.
2. Give signal to controller.
3. Controller starts Electric motor.
4. Wheels are powered by electric motor.
5. Clutch is disengaged and Engine is Switched off.

Is it possible to have a controller that can do all the above mentioned processes? Can you give some suggestions?



SPEED CONTROLLING:

Engine will be controlled the same way as it does in a normal scooter (mechanically).
Electric motor can be controlled by attaching a potentiometer on the accelerator lever itself.

We also plan to attach a clutch if possible between the wheel and the engine so that when the electric motor starts we can disengage the engine and then switch it off and engage it back when the engine starts.

Is it ok to run the wheels with the electric motor while the engine is switched off ? Is it possible?
The reason is because the engine would then be directly connected to the wheel by a belt/chain and motion of the wheel would rotate the gear and thus the belt/chain and thus the engine output shaft. Would there be any drawbacks?
I think because of this the motor would have to take the load and hence we are planning to use a clutch.




I would like you to help me out with this project.
I will be posting the future changes that we will be making in the design of the kit.
You can point out the drawbacks and give in your ideas.

Thanks,
Shoeb

[srishiva]

What if the battery is charged below optimum for the motor ? Wouldn't it be easier to use the engine as a generator and drive the wheels solely on electric power, like a plug in ? Just my 2 cents

Best of luck and hope you are successful at it.

[siddartha]

are you planning to mount the motor on the front mud guard area such that it can drive the front the wheel?

[star_aqua]

Originally Posted by SRK

CONCEPT:
Here is our concept.
The scooter that we plan to use will be a Gearless type (Kinetic, Honda activa, etc.)
We would use a DC motor to power the wheels.

Nice initiative Shoeb! wel, just my 2 cents for below.

Originally Posted by SRK

Speed sensor detects speed and sends a signal to the Switching circuit or Controller.

Is it possible to have a controller that can do all the above mentioned processes? Can you give some suggestions?

Yes it is possible to have controller which can do all you need. e.g 8051?
you need to do lot of programming. should be interfaced with a tachometer to read the speed. But please don't ask me how, because am not expert in this.
you can also setup your own tachometer with a toothed profile wheel and a indutive sensor. but converting this into digital needs a pwm signal sensing and processing with timers. again involves programming.

Originally Posted by SRK

We also plan to attach a clutch if possible between the wheel and the engine so that when the electric motor starts we can disengage the engine and then switch it off and engage it back when the engine starts.

Is it ok to run the wheels with the electric motor while the engine is switched off ? Is it possible?
The reason is because the engine would then be directly connected to the wheel by a belt/chain and motion of the wheel would rotate the gear and thus the belt/chain and thus the engine output shaft. Would there be any drawbacks?
I think because of this the motor would have to take the load and hence we are planning to use a clutch.

The gearless vehicles uses auto clutch(mechanical). they get engaged only when engine drives and disengages when the engine is driven by the vehicle(free wheeling).

Originally Posted by SRK

You can point out the drawbacks and give in your ideas.

Wanted to know whether you guys calculated how much torque is required at wheels inorder to move the vehicle and based on that what is the rating of motor to be used. most important is the battery, and its rating, weight involved.

All the best for you project!

[ilangop]

Hi,
1 small suggession. Your task could be simplified by retrofitting a hub wheel motor from the e-bikes commercially available. You can make use of the same current convertors used in ebikes. It will also take care of the battery management system. All you will have to concentrate is only on the algorithm to control the on/off of the engine, Governing of engine, and controlling the clutch. That itself would be a huge task for a student project lasting for 6 months to 1 year.

You would have to replace the centrifugal clutch or variomatic coupling in the suggested scootrettes with an electromagnetic clutch (like one from an automototive AC compressor).

[abhinav.gupta88]

No idea about how it will be done. But then seems an amazing project.
Hope you get success with it. All the best.

[Sprucegoose]

you get electric motors for cycles, im sure it can be ported to a scooter.
basically there is a regulator that is on the handle bar. You use that to control the speed of the motor and whether it is on or off.

I think the motor charges the battery if it is in the off position.

It is used to assist climbling up hills / for cruising on a plane surface.

[_abhay_]

8051 will be a better choice for control , simple and easy.

Speed measurement - use a permanent magnet and a hall effect sensor , there are a number of algorithms to compute speed (currently am planing on a DIY dgital speedometer using 8051 for my 150 DTSI , non digital of course) that should be helpful for your project.

when you plan to switch over from battery power to engine power ie above 20kmph , i guess the engine should already be doing more RPM than idle for a seamless transfer. If yes how do you know how much RPM is required. Seems more easier said than done.

Suggestion - can the motor be used as a generator when the petrol engine kicks in. to change the batteries.

I can be of some help with actuators and sensors and 8051 , feel free to ask.

Are you planing to create a working model or just want to showcase the concept ?

[SRK]

Originally Posted by srishiva

What if the battery is charged below optimum for the motor ? Wouldn't it be easier to use the engine as a generator and drive the wheels solely on electric power, like a plug in ? Just my 2 cents

Best of luck and hope you are successful at it.

That is a nice idea too. I think this type is called the Series Hybrid.
But this would mean that we will always have to run the engine.

Originally Posted by siddartha

are you plannin to mount the motor on the front mud guard area such that it can drive the front the wheel?

No we are planning to mount it on the rear wheel. The front assemble won't have any changes.

Originally Posted by ilangop

Hi,
1 small suggession. Your task could be simplified by retrofitting a hub wheel motor from the e-bikes commercially available. You can make use of the same current convertors used in ebikes. It will also take care of the battery management system. All you will have to concentrate is only on the algorithm to control the on/off of the engine, Governing of engine, and controlling the clutch. That itself would be a huge task for a student project lasting for 6 months to 1 year.

You would have to replace the centrifugal clutch or variomatic coupling in the suggested scootrettes with an electromagnetic clutch (like one from an automototive AC compressor).

Thanks, using a hub motor is on our list. May be we could just use the whole setup present on current e-bikes like you said.

Originally Posted by star_aqua

Yes it is possible to have controller which can do all you need. e.g 8051?
you need to do lot of programming...... processing with timers. again involves programming.

The gearless vehicles uses auto clutch(mechanical). they get engaged only when engine drives and disengages when the engine is driven by the vehicle(free wheeling).



Wanted to know whether you guys calculated how much torque is required at wheels inorder to move the vehicle and based on that what is the rating of motor to be used. most important is the battery, and its rating, weight involved.

All the best for you project!

Thanks!
We will be doing the analysis, after we are sure of getting the controller made. Then we can select a appropriate motor and battery.

You said that these scooters use Auto-Clutch. Does this mean when the engine is off and the wheel rotates it becomes a free-wheel?

Originally Posted by abhinav.gupta88

No idea about how it will be done. But then seems an amazing project.
Hope you get success with it. All the best.

Thanks!

Originally Posted by Sprucegoose

you get electric motors for cycles, im sure it can be ported to a scooter.
basically there is a regulator that is on the handle bar. You use that to control the speed of the motor and whether it is on or off.

I think the motor charges the battery if it is in the off position.

It is used to assist climbling up hills / for cruising on a plane surface.

I feel those motors on the cycles may not be able to move the scooter.
A motor from an ebike could be considered instead.

Originally Posted by _abhay_

8051 will be a better choice for control , simple and easy.

Speed measurement - use a permanent magnet and a hall effect sensor , there are a number of algorithms to compute speed (currently am planing on a DIY dgital speedometer using 8051 for my 150 DTSI , non digital of course) that should be helpful for your project.

when you plan to switch over from battery power to engine power ie above 20kmph , i guess the engine should already be doing more RPM than idle for a seamless transfer. If yes how do you know how much RPM is required. Seems more easier said than done.

Suggestion - can the motor be used as a generator when the petrol engine kicks in. to change the batteries.

I can be of some help with actuators and sensors and 8051 , feel free to ask.

Are you planing to create a working model or just want to showcase the concept ?

Thanks!
It would be really great if you could help us out with the electronics.

You have a nice point there about the switching.
I think the engine has to be started at about 16-19km/hr and as soon it reaches 20km/hr the switching can take place. By doing this the engine would have reached at a higher rpm.

Yes a motor can be used as a generator when not in use but I think it will have to be used in the reverse direction (will find that out).

We are planning to make a working model.
Actually we could have gone for training at any service-centre but we decided to use that time to make this project (hope nothing goes wrong).

[srishiva]

Originally Posted by SRK

That is a nice idea too. I think this type is called the Series Hybrid.
But this would mean that we will always have to run the engine.

Engine would run only when the battery is below optimum level. The battery could be charged at home or anywhere. Small trips this way will not require the engine to be run at all. This is how GM's volt will be like. Simplifies a lot of stuff.
So the drive train is electric only with engine acting as a generator when needed.

[Technocrat]

This surely looks like an interesting project.

While deciding on the electric motor make sure its a heavy duty one as all Kinetic, Activa etc are all quite heavy to be driven by an electric motor.

All the Best

[SRK]

Originally Posted by srishiva

Engine would run only when the battery is below optimum level. The battery could be charged at home or anywhere. Small trips this way will not require the engine to be run at all. This is how GM's volt will be like. Simplifies a lot of stuff.
So the drive train is electric only with engine acting as a generator when needed.

This will almost simplify the whole setup.
We wanted to do a parallel hybrid but it seems a bit difficult to achieve at student level.(specially when we don't have practical knowledge.)
I will give this idea to my friends on your behalf. Thanks!

Originally Posted by Technocrat

This surely looks like an interesting project.

While deciding on the electric motor make sure its a heavy duty one as all Kinetic, Activa etc are all quite heavy to be driven by an electric motor.

All the Best

Thanks,
We will use a heavy duty motor for sure.

[hollywoodhogan]

interesting and relevant project for todays world. good luck.

my inputs -
the centrifugal clutch is mounted on the gearbox end (rear wheel)and connected to the engine crank via the belt-vario-drive. once the rear wheel starts rotating beyond a designated speed, the clutch will engage and drive the belt and then the vario and then the engine will start to crank over and overload the motor drive.

using a vario scooter initially to all and me appears to be the best choice but the above issue is a complex one to resolve IF the electric motor is going to push the vehicle beyond the centrifugal clutch engagement speed, which is not much. mounting the batteries in the floor board and the motor on the front wheel would be easy but then it would result in traction problem on loose surfaces which could be risky.

[speed0mania]

hi SRK! well my final year project was similar to this i made a hybrid gokart so been through all these niggling problems! ok now my suggestions:-

-use PWM (pulse width modulation) for speed control, very easy to program.
-instead of keeping speed as control to switch b/w engine and motor use the throttle lever as in upto a certain twist uses motor after which engine switches on. This is helpful as whenever the driver needs more power he will instinctively accelerate higher giving him engine power.
-use a larger alternator to charge battery by starting engine when bat is low again very simple to programe on an 8051.
-My suggestion would be to go for a YOBike wheel mounted motor, with the controller , this way half the touble of getting a speed controller is gone, plus youve got a motor thats mounted into your wheel hub! You can buy these as spares from your local Yobike dealer, I found out during my research.
- try using regenerative braking, if possible.
-the only problem you will face with using a hub motor is that you probably wont be able to disengage it, you can look at other motors they use as well.
- add a system like the new bosch system where, when you're waiting for more than a fixed time on idle with the brake lever pressed the engine switches off.

But you will need to get a sturdier starter motor on this engine as a normal one would pop soon!

Hope i have been of some help and not added to your misery! PM me if you have any queries or need any other help will be more than happy to help you out, if you want i can mail you my project report too. Just remember don't compromise anywhere, My accelerator cable broke 2 hours before my viva went mad running around and replacing it just in time!

[_abhay_]

Originally Posted by SRK

SWITCHING CIRCUIT/CONTROLLER:
This is the most important part and the one where we are facing a problem. We don’t know much about Electronics/Programming and will need some help from an expert.
Basically our requirement is as follows:
Speed sensor detects speed and sends a signal to the Switching circuit or Controller.
Conditions:
(i) At rest (0km/hr):
1. Detect speed (i.e. 0km/hr)
2. Give signal to controller.
3. Controller starts electric motor.
4. Wheels are powered by electric motor upto max speed of motor (say 20km/hr)

(ii) Above max speed of Electric motor (say 20km/hr).
1. Detect speed
2. Give signal to controller.
3. Controller Starts Engine and Engages Clutch.
4. Wheels are powered by the engine.
5. Controller switches off the electric motor.

(iii) 0-5km/hr:
1. Detect speed, if speed falls below 5km/hr or scooter comes to rest then go to step2.
2. Give signal to controller.
3. Controller starts Electric motor.
4. Wheels are powered by electric motor.
5. Clutch is disengaged and Engine is Switched off.

Is it possible to have a controller that can do all the above mentioned processes? Can you give some suggestions?

The control action you are planning needs to be much more coplex than this. What you are planning to have is a simple ON/OFF control action. This type of controller is prone to a common problem known as "Hysteresis". As in condition 2 ie speed above 20KMPH if the bike is running on road where you are constantly operating in that speed range (normal traffic condt) , the controller will keep switching between the motor and engine, just imagine this happening too frequently BANG !!! .
To avoid this we need to find if the bike is accelerating or decelerating and accordingly add an offset to the switch over point (easier said than done).
I have some experience with PID control actions not sure if that will be of any help in your project as am not familiar with the mechanical aspects of the design.

Considering the complexity i believe 8051 might not be enough, and we might have to send the data to a PC or a linux based machine to resolve the algorithm.

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