Does a brushless motor require more power than an ordinary motor? Also does it require AC or DC current? If AC current , then how to convert DC to AC? Can we put a power converter in the car?

If you consider the power to work done ratio (efficiency), Brushless motors (abbreviated as BLDC) are much efficient because components such as friction from brushes is eliminated and torque does not decrease linearly as with brushed motors, overall maintenance due to wear and tear of commutator is lesser.

BLDC are DC motors. In fact they've a small switching circuit inside that switches the current in the correct sequence to the coils, causing rotation.

Wealth of information: http://en.wikipedia.org/wiki/Brushless_DC_electric_motor

Motors do not require power. They draw as much power (energy/time) from the batteries as the loads pressed upon them mandate.
Brushless motors are capable of delivering much more power than brushed motors of similar sizes as their efficiency is much higher & they are electrically & mechanically more robust to handle those huge power levels.

They are basically Permanent Magnet Synchronous Motors (PMSM). When 3 phase AC supply is given, then they are called PMAC motors & when 3 phase switched square-wave DC supply is given, then they are called BLDC motors.

For mobile applications like RC vehicles, we have to use them as BLDC as AC power cannot be stored. DC power can be stored in batteries. To convert simple zero frequency DC supply to 3 phase variable frequency one, we have to use a work of 'engineering art' called Electronic Speed Controller (ESC).

But remember that to work as BLDC or PMAC, we require some kind of feedback of rotor position to keep rotor in sync with the supply. In case of BLDC, Hall effect sensors or back EMF sensorless technique is used. In case of PMAC, apart from the feedback techniques used for BLDC, optical sensors are also used.

In short, actually, what we are using in our brushless cars is very futuristic & is the future of our automobile industry! (only if battery tech can evolve... ) Thank God that we live in these times  

thank you girishsarwal and 1firefly2. there are some doubts remaining though :
1.Our car battery has DC current, right?
2.A BLDC motor means it needs DC or needs AC and coverts it into DC?
2.Can i take a normal RC car from flipkart (for eg.) with a ratio of 1:16 and put a BL motor in it?

Hi,

1. Batteries store DC.
2. BLDC needs DC supply converted to switched 3 phase DC which is done by ESC.
'2'. Almost No. For that you need a hobby grade car which has standardized design of chassis to modify motor, ESC, receivers as they are all again standardized across R/C industry. Majority of toy grade design can accommodate the electronics that comes with it & also most cannot be dismantled to do modification. That's why almost no.

Though, you can still tinker with it by extensive cutting, chopping, whittling... which in my opinion is not worth it.
For a BL motor, you will be needing a BL ESC too...which 'may' require a compatible Servo & Radio...Will cost you a lot!!
Go get one RTR hobby grade car & see the difference.

thank you 1firefly2, you opened my eyes!

 

Since we are having an AC vs DC discussion...

@anwar, nope, i NEVER wondered which is more painful...