RC India

i'm making a quadrotor uav any one sugest which motor is best for it brushed or brushless.....

Brushless, obviously. They are significantly more efficient.

That does bring up the question though. Other than cost, are there any other advantages to brushed motors ? Any application where brushed motors make more sense than brushless ?

Found this:

http://www.dynetic.com/brushless%20vs%20brushed.htm  {site down}
Use this linkhttps://web.archive.org/web/20160310172252/http://www.dynetic.com/brushless%20vs%20brushed.htm

BLDC Motor Pros
Electronic commutation based on Hall position sensors
Less required maintenance due to absence of brushes
Speed/Torque- flat, enables operation at all speeds with rated load
High efficiency, no voltage drop across brushes
High output power/frame size.
Reduced size due to superior thermal characteristics. Because BLDC has the windings on the stator, which is connected to the case, the heat disipation is better
Higher speed range - no mechanical limitation imposed by brushes/commutator
Low electric noise generation

BLDC Motor Cons
Higher cost of construction
Control is complex and expensive
Electric Controller is required to keep the motor running. It offers double the price of the motor.



Brushed Motor Pros
Two wire control
Replaceable brushes for extended life
Low cost of construction
Simple and inexpensive control
No controller is required for fixed speeds
Operates in extreme environments due to lack of electronics

Brushed Motor Cons
Periodic maintenance is required
Speed/torque is moderately flat. At higher speeds, brush friction increases, thus reducing useful torque
Poor heat dissipation due to internal rotor contsruction
Higher rotor inertia which limits the dynamic characteristics
Lower speed range due to mechanical limitations on the brushes
Brush Arcing will generate noise causing EMI

In a heart beat - brushless. Brushed are so antique :P and we live in 2010 :salute:

in my circuit there are 4 PWM output from microcontroller for running motor 1 for each motor, but in brushless motor there is showing 3 input line, so i've the problem that how to connect it...

I am not the best person to comment on this.

BAsically, if your signal is of the right type (or if you make it so), you can feed it into a brushless speed controller (ESC), and then let the ESC drive the brushless motor.

For a brushless motor you need a brush-less speed controller, which takes a compatible pwm input and converts it into 3 - 120 degree phase shifted ac voltage. So a brushless controller is inevitable. Note that brushed motors are DC and brushless are AC motors.

i've the circuit for running brushed motor which has 2 lines, weather brushless motor run by this....

If these are your power lines to the Brushed motor, then No. If these are PWM lines from a chip, then there are chances that u can use a ESC and run the motors. But not sure if those PWM signals are compatible with the ESCs on the market. Me not an expert in micro electronics. :(

i'm using PIC18F4431 microcontroller which gives PWM to run brushless motor also, so how i connect this PWM to ESC to run the motor and much power is required for this ESC and brushless motor.

This should do it, hopefully !

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en012145

The details are in this link from the above page (http://ww1.microchip.com/downloads/en/AppNotes/00899a.pdf) and the source code is also included.

You will still need to choose the right sized brushless ESC, brushless motor and appropriate prop, but that is largely driven by the weight of your quad-rotor.

hi denis

can u give more info ?? are the PWM signals looking similar to a servo control signal ?? (refresh rate or frequency is 50-60hz or 20msec in which high pulse is only b/w 1 - 2 msec ? rest of the time low)

sahil

http://www.pabr.org/pxarc/1.1/doc/pxarc.en.html

http://www.pyroelectro.com/tutorials/servo_motor/theory.html

thanks Anwar sir for ur reply.

how much PWM require to run one brushless motor..

Can you clarify your question a bit ? 

Are you talking about the peak voltage ? If so, my understanding is that it is 3.3v to 5v (5v is preferred).

Look at the figure Sahil posted. That is the signal you need to generate from the PWM output to the brushless ESC. A 1ms pulse corresponds to 0% throttle and 2ms is 100% throttle. Repeat the pulse every 15-20ms.

i mean, i have 4 PWM output so how to connect 4 brushless motor from this.

If I understood this correctly, the obvious solution is to use 4 different brushless ESCs, one for each brushless motor.

ESCs are costlier than motor so can u suggest me any cheap n good ESC for my quadrotor.

ESC selection is a bit involved topic, as you can easily burn them up (or your motor), if you are not careful about your selection.  The first thing is that you should have some target AUW (all up weight) for your quad rotor. Based on that, you should pick the specs for the motor + ESC + prop.  Which brand you go for can be driven by cost, as most of the ones available in the market now are good. But without having a target weight and you working towards that weight, it might be tough for people to respond further on this.

I request others to pitch in, especially the electric folks.  There are also other threads here on the same topic, please do a search.

i think its the same connection as u connect servo to a microcontroller
two wires will  be supply and ground(connect to power supply)

and third wire to microcontroller port-for generating pwm as stated above.

brushless are good because more power
 

check this ..this guy has build it
http://quaduino.org/

it includes all the shopping list and source code
will be really helpful

For a quadrotor UAV, brushless motors are generally preferred over brushed motors due to their higher power-to-weight ratio, greater efficiency, and longer lifespan. Brushless motors also have fewer maintenance requirements compared to a brushed motors. For these brushless motors, you can refer to https://robu.in/?s=brushless+motors&product_cat=0&post_type=product.