We have a Hubsan quadcopter/drone that has 4 brushed motors (BDC) and we want replace them with Brushless Motors (BLDC).

One of us that is more advanced at this conversion project has connected the 4 ESC (necessary for (BLDC motors) to the correspondent Mosfet. The “signal wire” of our ESC is a twisted par with white and a black wires, so the PWM Signal/White wire is connected to the Gate and the Signal/Ground to Source of Mosfet.

With these connections the BLDC are working, so the quadcopter is flying! The problem is for that happen we must keep the brushed motors connected to the Flight Controller/Receiver (integrated) and spinning at same time as BLDC (see picture) ! Each Brushed M. is connected by two wires to the correspondent + and - of the FC/Receiver!

I put the question in another forum if Resistors could replace the, now, useless brushed motors, but the answer was no, if I understood well the explanation, so I must follow another track that is decrease RPM.

Once the Hubsan Flight Controller is proprietary and no documentation is available, I cannot control the speed by traditional methods, so I want to add one or more components to reduce "artificially" the RPM of these motors and with this minimize the weakness of brushed motors at quadcopters, the main reason for our conversion project (we must replace the brushed motors regularly).
Note - these brushed motors draw 1V & 0.05A at idle and 6.5V & 1A at full throttle!
because they die)

 

in these ESC white = orange and black=brown. sorry

 

We have a Hubsan quadcopter/drone that has 4 brushed motors (BDC) and we want replace them with Brushless Motors (BLDC).

One of us that is more advanced at this conversion project has connected the 4 ESC (necessary for (BLDC motors) to the correspondent Mosfet. The “signal wire” of our ESC is a twisted par with white and a black wires, so the PWM Signal/White wire is connected to the Gate and the Signal/Ground to Source of Mosfet.

With these connections the BLDC are working, so the quadcopter is flying! The problem is for that happen we must keep the brushed motors connected to the Flight Controller/Receiver (integrated) and spinning at same time as BLDC (see picture) ! Each Brushed M. is connected by two wires to the correspondent + and - of the FC/Receiver!

I put the question in another forum if Resistors could replace the, now, useless brushed motors, but the answer was no, if I understood well the explanation, so I must follow another track that is decrease RPM.

Once the Hubsan Flight Controller is proprietary and no documentation is available, I cannot control the speed by traditional methods, so I want to add one or more components to reduce "artificially" the RPM of these motors and with this minimize the weakness of brushed motors at quadcopters, the main reason for our conversion project (we must replace the brushed motors regularly).
Note - these brushed motors draw 1V & 0.05A at idle and 6.5V & 1A at full throttle!
View attachment 132022 because they die)

The motor wires are likely monitored by the brushed motor controller to measure RPM (via the inductive kick of the brushed motor). There is no good way to measure this on a brushless D.C. Motor because the mosfets are not allowing current flow all the time. Buy a hobby grade quadcopter rather than a Hobson Toy.

 

The motor wires are likely monitored by the brushed motor controller to measure RPM (via the inductive kick of the brushed motor). There is no good way to measure this on a brushless D.C. Motor because the mosfets are not allowing current flow all the time. Buy a hobby grade quadcopter rather than a Hobson Toy.

If they measure RPM it will be a problem, but let's think they don´t!
At my searches, I saw twice experts talking about a linear regulator. One of them was more detailed like this: "I think you could do simple negative source resistance (also called IR compensation) with an op-amp driving the reference terminal of a linear regulator, which might be appropriate for a small motor". Once was an old question I cannot ask how to apply this suggestion once I am not an expert at electronics. Of course I know what is a linear regulator, but don´t know where to put it in this context!
Two notes 1)The Hubsan 502e has already GPS, which is a strong reason to keep it ... with brushless motors if possible! 2) as I said at main post, the h502e is flying with brushless motors connected to mosfet, so when you say "are not allowing current flow all the time" you talk about "measuring"?

 

If they measure RPM it will be a problem, but let's think they don´t!
At my searches, I saw twice experts talking about a linear regulator. One of them was more detailed like this: "I think you could do simple negative source resistance (also called IR compensation) with an op-amp driving the reference terminal of a linear regulator, which might be appropriate for a small motor". Once was an old question I cannot ask how to apply this suggestion once I am not an expert at electronics. Of course I know what is a linear regulator, but don´t know where to put it in this context!
Two notes 1)The Hubsan 502e has already GPS, which is a strong reason to keep it ... with brushless motors if possible! 2) as I said at main post, the h502e is flying with brushless motors connected to mosfet, so when you say "are not allowing current flow all the time" you talk about "measuring"?

Google: Hubsan brushless conversion

There seems to be some tricks out there - RCGroups.com

 

You could try adding components R1,C1 to integrate the PWM output of the ESC, as below, to generate a signal which might fool the controller into thinking there's a BDC motor attached. No guarantee it will work, though.


Disconnect the BDC motor if using this circuit.

 

You could try adding components R1,C1 to integrate the PWM output of the ESC, as below, to generate a signal which might fool the controller into thinking there's a BDC motor attached. No guarantee it will work, though.
View attachment 132048

Disconnect the BDC motor if using this circuit.

For my knowledge this is the type of answer I am looking for, not ignoring the merit of theoretical explanations that are fundamental to join both aspects (theory and real implementation)! thks

 

Ok, not being an electronics expert I will try to interpret what you put at the circuit but I will use a picture that show what we are doing with Mosfet!
1) From the BLDC we have 3 wires that connect to ESC (the order is not relevant because only rotation direction is involved). Here my first doubt at your circuit because apparently these 3 connections ( BLDC to ESC) would be different to you! Am I interpreting incorrectly?
2) You put at ESC, to simplify, + and -. Once a quadcopter ESC usually have 4 wires : + and -, to power, and a twisted par that is the Signal (normally white for the "signal" itself and black for Signal/Ground), I presume you are talking about these 2 wires. Correct? ( What we have now is connect the signal/white to Gate of Mosfet and signal/ground to source).
From 1 and 2 I conclude that NMosfet and BDC connectors must work together? I ask this because I tried one thing I read at a post somewhere that we could fool the controller with a Resistor and a Zener diode, directly at BDC connectors without any Mosfet involved! I had no success (I could not repeat again because my controller fried by my mistake and I am waiting for a new one), so the reason I am still looking for a solution!
So there is also a difference once I had used a Diode instead a Capacitor that you suggest!I put here these comments because you said you never tried, so more information can be useful!

 

 

New at forum, so problems at uploading files! Sorry

 

My image finaly here!

https://forum.allaboutcircuits.com/...0/?temp_hash=492526955ff7792bea8ce2fde22cee6d

 

Here my first doubt at your circuit because apparently these 3 connections ( BLDC to ESC) would be different to you! Am I interpreting incorrectly?

Yes, it's different. But all 3 output connections to the BLDC coils have a similar drive signal, so any one of them could be used as a PWM source. Isn't the input signal to the ESC a PWM signal?

Edit: You can use the 'Upload a file' button to post pics here.

 

Hello,

I see you are trying to link images to your local harddisk.
This will not work.
Please use the "Upload a File" button below the reply window, to add the images.

Bertus

 

Hello,

I see you are trying to link images to your local harddisk.
This will not work.
Please use the "Upload a File" button below the reply window, to add the images.

Bertus

I tried the "upload a file" option but I am getting errors, so I found another way!
Time to restart my laptop!

 

Hello,

The problem could be the flash uploader.
Go to your profile, the select preferences and remode the tick as in the picture:



After that, you should be able to upload files.

Bertus

 

I restarted but the same error! I am using Firefox!
"The following error occurred"
"There was a problem uploading your file"

 

Hello,

Did you tick off the flash uploader as given in the picture above?

Bertus

 

Hello,

Did you tick off the flash uploader as given in the picture above?

Bertus

Something strange at my Windows 10! I cannot access any item of my Account, included Preferences at both browsers: Firefox and Chrome. I will try Edge now!

 

I think that is something connected to Flash! Going update it now!

 

Hello,

There are some limitations for members with less than 10 posts.
As you have now 12 posts, you should be able to do everything.
I have removed the flash tick for you.
You should be able to upload files now.
You will see the windows explorer dialog for locating the file to upload.

Bertus