Question : the theory of brake operation
12-19-2015, 04:26 AM
#1
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Question : the theory of brake operation
Hello
I want to understand the operation of the brake ( What happens between the motor and the controller ),
What voltages the controller provides to the motor during brake operation ?
What is the difference electrically between the situation not brake , to Activating the brakes ?
Thanks
kobi
I want to understand the operation of the brake ( What happens between the motor and the controller ),
What voltages the controller provides to the motor during brake operation ?
What is the difference electrically between the situation not brake , to Activating the brakes ?
Thanks
kobi
12-19-2015, 08:20 AM
#2
My Feedback: (3)
Take a motor
Spin it up using a drill
Remove the drill and see how long it takes to spin down
Repeat the same experiment but short the winding and see how long it takes to spin down
The controller us just doing the same thing
it is sometimes called "slow decay" in electronics literature
Spin it up using a drill
Remove the drill and see how long it takes to spin down
Repeat the same experiment but short the winding and see how long it takes to spin down
The controller us just doing the same thing
it is sometimes called "slow decay" in electronics literature
12-20-2015, 05:29 AM
#4
My Feedback: (3)
Yes, in a way.
When the motor is being driven by voltage signals from the ESC, it is acting as a motor...put a voltage across a winding (coil), generate current, which generates a field, which can interact with a magnet and produce a force (motion). Basic motor stuff.
When the motor is NOT being driven by the voltage signals from the ESC, it is then spinning and acting as a generator. As the motor turns, it produces a voltage on the coils (due to the magnets passing by the windings ... change in flux, etc).
Now, if you short the windings, you produce a braking force, as the voltage on the coils produces a current which acts as an electromagnetic brake. Again, if you search for slow decay, you will find additional details and explanation (along with pictures, which is always nice)
If the ESC turns the 'short circuit' ON/OFF a fixed rate, it can produce a fixed braking force. That is how an ESC provides a % braking...if it applies a short and leaves it there, you have 100% braking...if it leaves the coil OPEN, you have 0% braking.
By using PWM, you can have anything between 1 and 99% braking by simply turning the short "on/off" at a fixed rate.
There are some other effects, like heat generation, but they really don't matter at this point.
When the motor is being driven by voltage signals from the ESC, it is acting as a motor...put a voltage across a winding (coil), generate current, which generates a field, which can interact with a magnet and produce a force (motion). Basic motor stuff.
When the motor is NOT being driven by the voltage signals from the ESC, it is then spinning and acting as a generator. As the motor turns, it produces a voltage on the coils (due to the magnets passing by the windings ... change in flux, etc).
Now, if you short the windings, you produce a braking force, as the voltage on the coils produces a current which acts as an electromagnetic brake. Again, if you search for slow decay, you will find additional details and explanation (along with pictures, which is always nice)
If the ESC turns the 'short circuit' ON/OFF a fixed rate, it can produce a fixed braking force. That is how an ESC provides a % braking...if it applies a short and leaves it there, you have 100% braking...if it leaves the coil OPEN, you have 0% braking.
By using PWM, you can have anything between 1 and 99% braking by simply turning the short "on/off" at a fixed rate.
There are some other effects, like heat generation, but they really don't matter at this point.
Last edited by ltc; 12-20-2015 at 05:31 AM.
