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How does a speed controller work?
An ESC (Electronic Speed
Control) is a device that controls the speed of the motor by turning the
motor on and off. Consider the circuit as a diagram shown.
To turn on the motor you
disconnect from its plug with Electronic Speed Controller. If you connect
and you stop the flow of current and the motor will slow down and eventually
stop turning. Proportional throttle control is achieved by varying the
amount of time the speed controller is on relative to the amount of time it
is off. For example, for 1/2 throttle, the switch in the speed controller is
on half the time.
In order to achieve smooth
throttle response, this switching in the speed controller must occur several
times per second. Inexpensive speed controllers typically perform this
switching 50 times per second. The reason why 50 times a second was chosen
is because this is the rate that control pulses are sent to each servo and
the electronics are greatly simplified if this rate is used. This is called
frame rate because the ESC operates at the same rate as the radio control
frames are updated.
How to attach the heat sink
to the speed controller ?
Please follow below steps:
1. Cut and tear open the shrink tubing.
2. Stick the heat conduction silica film to the flat side of the heat sink,
then attach the heat sink to the speed controller.
3. Wear the shrink tubing and use hair drier for fixation.
4. Use a designing knife to cut stripes on the fins of the heat sink, then
use the hair drier again.
You may refer to our movie on the below web site
http://www.gws.com.tw/english/service/movie/movies.htm.
How
does a motor brake work?
When a DC motor is spinning with the speed controller turned off it is
serving as a generator. With the propeller wind milling the motor (generator
now) is producing a voltage at the motor terminals but is doing no work.
When you put a short across the motor terminals the motor must now work hard
to try to generate the same voltage across a dead short. It might cause the
motor (generator) to slow down. The motor short is provided by an electronic
switch in the speed control.
How long can I fly once
the cutoff function takes place?
We’re sorry! It’s hard to respond you! This depends on several factors and
there is no good answer to fit it.
What
does the advantage of a High Rate Controller do for us?
This simple responding answer is the efficiency is greatly increased over
that of a frame rate control.
An electric motor wants to
turn at a certain speed that depends on the voltage that is being supplied
to it. Our best speed controller should provide a nice clean DC voltage that
varies from a maximum that is the same as the battery down to zero volts.
All GWS electronic speed
controllers operate very much like this method.
What is
a BEC and how does it relate to the speed controller?
BEC stands for Battery Eliminator Circuit. The battery eliminating is your
receiver pack. The BEC is a completely separate circuit from the rest of the
speed control. It is generally a one to two amp linear regulator that
converts the motor battery voltage to a regulated 5 or 6 volts to power the
receiver and servos.
What is a cutoff?
To be frankly with you, a cutoff is a circuit that is added to an esc
equipped with a BEC to try to prohibit the motor battery from being run dead
and causing a crash when the input voltage goes below 5.25 volts. GWS speed
controllers not only have a BEC but have a cutoff circuit. We‘ll highly
suggest that you shouldn't use a car type controller in a plane with the BEC
active.
Where
do I plug in my BEC speed
controller?
There will be schemes shown in GWS airplane’s instructions. Please read the
instructions carefully and thoroughly before assembly in order to achieve
safe operation with the BEC speed controller.
Can I
control 2 motors with one controller?
This might be done if you use a sensor controller and the motors are closely
matched. It‘s possible to get some
problems with the motor initial startup for this configuration. In order to
send the correct signals to the motor(s), the controller has to analyze the
configuration. Sometimes one motor may fail to start or may even
start in reverse. There is little that can be done about this other than to
cut the throttle and try again.
About ESCs,
BECs, and servo failure ?
After a number of in-flight failures of the same
type of servo under different conditions, I started a thread in another
vendor forum asking for help:
Servo failures—what's going on?
In that thread, a number of people have wondered if and how ESCs used under
certain (recommended and non-recommended) conditions may have contributed to
servo failures without themselves being damaged (i.e. a servo fails, but the
ESC is undamaged). That thread seems to have reached a point where more
insight on the functioning of ESCs and BECs would be very helpful.
Here are the two set-ups:
1. Pixie 7P, 3 micro servos, 3s lipo, dual IPS ~2 A average draw
2. Phoenix 10, 3 micro servos, 3s lipo, CD rom motor ~ 2 A average draw
In the first case, it has been rightly pointed out to me that the BEC on the
Pixie 7P is overloaded with 3 servos on 3s lipo. What would the expected
failure be in this case?
In the second case, it is my understanding that the ESC and BEC were not
overloaded. Or am I missing something?
It is well worth pointing out that my one and only goal here is to avoid
future crashes from servo failure!
I think that servos can be damaged if BEC fails and feeds not 5V as it is
designed to do, but full battery voltage-11.1V with 3S LIPO for example.
If it is overloaded(as in too much amp draw from servos with too high
voltage) -BEC will shutdown, or loose voltage output to servos, then you
loose control of your aircraft. But I don't think that voltage going low can
damage servos.
So if you are continuing to use your ESC's and no more servos died it would
mean that BEC output is in normal range, you could measure it with voltmeter
to be sure.
CC representatives will give you better explanation I hope, as I am not sure
how exactly BEC shuts down
Not to stray from Andrew's initial question, I'd like to know the different
ways a BEC can fail and the consequences of those different BEC failures.
Whether natural or user induced. David
#1 set-up - you are correct, it is simply out of spec and will not work at
all, or for long. The BEC chip will be almost constantly overheating and
shutting down, until the point of failure (closed circuit) with no output.
#2 is fully within specs, and does not pose an issue for even the BEC to
shut down from overheating at all, UNLESS a servo is stalled, or the pot is
damaged/partially burned/has dead spots and so on. Even good small servos
when stalled can draw surprising amounts of current, and with pot damage can
basically be a direct short.
The only real (or induced) damage any controllers BEC can cause (we all
basically use similar linear regulator circuits) would be from providing
less than 5v in an overheating and shutting down situation. Mike from Hitec
would know if a constant shutdown-reboot cycle would do anything negative to
a servo. From what I know about them, I don't see how it could be harmful#1
set-up - you are correct, it is simply out of spec and will not work at all,
or for long. The BEC chip will be almost constantly overheating and shutting
down, until the point of failure (closed circuit) with no output.
I just completed GWS
Spitfire and a ICS300 speed control. #1 there were no instructions how to
install the heat sink. #2 all the controls work fine but the prop stops
turning in a short while.If I wait just a very short time, it will run again
but only for a short time and stop.I am using the same prop and motor that
came with the kit.There are several in our club that are preparing for
racing. I have learned from a fellow at the hobby shop that the timing of
the motor can done to increase rpm. Is this correct? If so, how do I do it?
First of all, cut the shrink tube and put the
heat sink on the back side of ESC (front side is ESC label) . Now install
the new shrink tube which has enclosed within the product, then use the hair
blower to shrink the tube. Furthermore, please refer the website
http://www.gws.com.tw/english/service/movie/movies.htm
I would like to use a
Li Poly battery with the ICS-5 controller. Is it safe and what is the auto
cut voltage for this controller? Is
ICS-5 a mis-typing of ICS-50? There is the spec of ICS-50 on
http://www.gws.com.tw/english/product/speed%20controller/50.htm,
please check. We do not recommend ICS-50 to handle Li-Po battery because
ICS-50 is a 2A speed control. Depending on the capacity of your batteries,
you might need a larger amperage speed control.
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