Tuesday, March 16, 2010

Brushless DC Motor modification and winding


Brushless DC Motor modification
My first speed 300 motor died after about half year of flying. In order to have better performances, I decide to change the engine into brushless. There are several choices of brushless motor in the market, such as the Hacker and Astro. By the way, there has been a mania for using modified CD-Rom motor in our RC models. Needless to say, I have joined the groups that are trying to find out the potential of these wildly available and low-price CD-Rom motors. 



Brushless motor winding by Utah Fyers #1 video
Video Radio control electric brushless motor winding tutorial  



Brushless motor winding by Utah Fyers #2 video
Tutorial on brushless motor winding presented by Utah Flyers.


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Sunday, March 14, 2010

Waveform of a Brushless DC Motor


Brushless DC Motor COMMUTATION SEQUENCE




Figure shows an example of Hall sensor signals with
respect to back EMF and the phase current. Figure 8
shows the switching sequence that should be followed
with respect to the Hall sensors. The sequence numbers
on Figure correspond to the numbers given in Figure 8.
Every 60 electrical degrees of rotation, one of the Hall
sensors changes the state. Given this, it takes six steps
to complete an electrical cycle. In synchronous, with
every 60 electrical degrees, the phase current switching
should be updated. However, one electrical cycle
may not correspond to a complete mechanical revolution
of the rotor. The number of electrical cycles to be
repeated to complete a mechanical rotation is determined
by the rotor pole pairs. For each rotor pole pairs,
one electrical cycle is completed. So, the number of
electrical cycles/rotations equals the rotor pole pairs.



BLDC Motor Waveforms
Figure is a graphical representation of the BEMF formulas
computed over one electrical revolution. To
avoid clutter, only the terminal A waveform, as would
be observed on a oscilloscope is displayed and is
denoted as BEMF(drive on). The terminal A waveform
is flattened at the top and bottom because at those
points the terminal is connected to the drive voltage or
ground. The sinusoidal waveforms are the individual
coil BEMFs relative to the coil common connection
point. The 60 degree sinusoidal humps are the BEMFs
of the driven coil pairs relative to ground. The entire
graph has been normalized to the RMS value of the coil
pair BEMFs.


Notice that the BEMF(drive on) waveform is fairly linear
and passes through a voltage that is exactly half of the
applied voltage at precisely 60 degrees which coincides
with the zero crossing of the coil A BEMF waveform.
This implies that we can determine the rotor
electrical position by detecting when the open terminal
voltage equals half the applied voltage.


BEMF waveforms and the zero-crossing points
The fact that one of the windings is not energized during each sector is an important characteristic of six-step control that allows for the use of a sensorless control algorithm. When a BLDC motor rotates, each winding generates BEMF, which opposes the main voltage supplied to the windings according to Lenz’s Law. The polarity of this BEMF is in the opposite direction of the energizing voltage. Figure 2, below, shows ideal BEMF waveforms and the zero-crossing points.






Waveform of a Brushless DC Motor ESC video
E-flite EFLA311, 20 A ESC driving an E-flite 450 motor.


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Friday, March 12, 2010

Brushless DC Motor Maintain Video


Brushless dcmotor maintain Part 1
Video how to take off brushless dc motor



Brushless dc motor maintain Part 2
Video how to clean brushless dc motor



Brushless dc motor maintain Part 3
Video how to assemble brushless dc motor


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Tuesday, March 9, 2010

Brushless Motor Construction


Brushless DC (BLDC) Motor Fundamentals



CONSTRUCTION AND OPERATING PRINCIPLE
BLDC motors are a type of synchronous motor. This
means the magnetic field generated by the stator and
the magnetic field generated by the rotor rotate at the
same frequency. BLDC motors do not experience the
“slip” that is normally seen in induction motors.
BLDC motors come in single-phase, 2-phase and
3-phase configurations. Corresponding to its type, the
stator has the same number of windings. Out of these,
3-phase motors are the most popular and widely used.
This application note focuses on 3-phase motors.


Brushless DC Motor - Basic structures



The construction of modern brushless motors is very similar to the ac motor, known as the permanent magnet synchronous motor. Fig.1 illustrates the structure of a typical three-phase brushless dc motor. The stator windings are similar to those in a polyphase ac motor, and the rotor is composed of one or more permanent magnets. Brushless dc motors are different from ac synchronous motors in that the former incorporates some means to detect the rotor position (or magnetic poles) to produce signals to control the electronic switches as shown in Fig.2. The most common position/pole sensor is the Hall element, but some motors use optical sensors.


Brushless Motor Construction Video
Machining A Brushless Motor with a lathe and drill press. Just a quick slide show of some motor contsruction tips before I added a small milling machine to my hobby shop. John  



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Friday, March 5, 2010

Brushless motor winding

Brushless DC Motor modification

A picture is worth hundreds of words. Here is a wiring diagram for the star configuration that I have found from the net. you are better to do this with great circumspection or it would be easily end up with a burned ESC. The first photo shown above is one group of the windings on the stator. Two groups are wound in the second photo while all three groups are wound in the last photo. The starts of each three groups are soldered together and the three ends are the phase wires that connect to the brushless controller.


Brushless Motor Winding Diagrams


The 'standard' Star diagram for
9-tooth stators & 12 magnets


Brushless motor winding by Utah Fyers #1
Radio control electric brushless motor winding tutorial video

Brushless motor winding by Utah Fyers #2
Tutorial on brushless motor winding video presented by Utah Flyers. 



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Monday, March 1, 2010

Home Built Brushless DC Motor Video


Brushless DC Motor
Video of a Home Built Brushless DC Motor


Brushless DC motor
Three students (16-17 years old) from the "Stedelijk College" in Eindhoven, the Netherlands designed and made this motor in one day! The motor turns with approximately 2000 rpm!


Homemade brushless motor
This is my homemade brushless motor. Or you could call it a fan! It's made from old junk and surplus components mostly. Better description is in the video!


home made brushless dc motor
Video home made brushless dc motor battery: Align 3 cell li-po 11.1v Reed switch 8 neodymium magnets no bearings were used (performance would have improved greatly if bearings were used on the spindle)


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