i am on the project to make a hybrid scooter, which will consume both petrol and battery....using PWM and hub DC motor....any advice and suggestion are more then welcome...the main problems i am facing right now are
1)how to changeover btwn engine and motor.
2)how much power is needed by the motor can use to drive common man's weight.
3)type of battery...

if any one can help me out i will be very thankful.....

 

I always wanted to make a little car like that, but my wife won't let me.
One way I thought about to keep it simple rather than have a bunch of fancy gears was to only drive the wheels with the electric motor and use the gas to charge the batteries. The size of the motor depends on a lot of things, but here is a link that may at least give you some ideas.

http://www.electricmotorsport.com/store/ems_ev_parts_motors_evt_3kw.php

 

I agree with ronv. The easiest way is to use the engine to drive a generator which then powers the motor driving the wheel with the battery connected in parallel. With that you just run off the battery until the battery voltage drops, and then start the engine. That way you can use a smaller engine and use the battery to provide a boost for accelerating or hills. That's the way the Chevy Volt does it.

You can get motor size estimates by looking at the motor size of commercial battery powered scooters. It really depends upon how fast you want to go along with how long you want the battery to last.

 

If it was me I would set it up with the DC hub motor in the front and have the back as a normal gas drive with the typical overrunning clutch type rear hub unless the DC drive hub can be set up with an overrunning clutch and sprocket on its outside.

If so put both drives on the rear.

Power wise figure at least one wheel Hp per hundred pounds of combined scooter and rider weight.

 

I always wanted to make a little car like that, but my wife won't let me.
One way I thought about to keep it simple rather than have a bunch of fancy gears was to only drive the wheels with the electric motor and use the gas to charge the batteries. The size of the motor depends on a lot of things, but here is a link that may at least give you some ideas.

http://www.electricmotorsport.com/store/ems_ev_parts_motors_evt_3kw.php

tell your wife it is great fun to play with machines and motors....me too not adding alot of stuff just simple DC hub motor and battery and simple changeover btwn motor and engine...coz adding too much funtion will make it more costly

 

If it was me I would set it up with the DC hub motor in the front and have the back as a normal gas drive with the typical overrunning clutch type rear hub unless the DC drive hub can be set up with an overrunning clutch and sprocket on its outside.

If so put both drives on the rear.

Power wise figure at least one wheel Hp per hundred pounds of combined scooter and rider weight.

i am using DC hub motor but iam using it in triangular formation coz it maximize the efficiency of the bike as well as i am also using it as a generator for the battery...how was your design working con you plz ore elaborate it will be very thankful...

 

If it was me I would set it up with the DC hub motor in the front and have the back as a normal gas drive with the typical overrunning clutch type rear hub unless the DC drive hub can be set up with an overrunning clutch and sprocket on its outside.

If so put both drives on the rear.

Power wise figure at least one wheel Hp per hundred pounds of combined scooter and rider weight.

yep me too i am using same method but in triangular formation of motor generator and engine coz it will hope so maximize the efficiency of the bike on battery...