StealthBurner CPAP & WS7040?

[Durahl]

I'm thinking about modding a CPAP Air Supply System into my StealthBurner and have noticed these usually being built with a WS7040 BLDC FAN and matching 24V Controller Board which is all fine and dandy but these Controller Boards seem to come with a 6-Pin Connector exiting two 3-Wire Bundles - One such Bundle leading to a 3-Wire Rotary Dial with the other Bundle either having lose ends to connect to something or being unpopulated.

Does anyone have any sources as to how that system is usually being controlled via the Printers MCU?
Also... Is there a particular reason as to why we need a WS7040 BLDC Fan with such a Controller to begin with instead of using another run of the mill - albeit larger - Radial 24V Fan?

Thanks in advance!

 

[Gallagher]

Hi,
I came across this looking for a solution for another problem, but thought I could offer some info.

CPAP fans are not so much fans as turbines. Unlike a radial fan, they focus mostly on pressure than airflow. Though the turbines in CPAPs spin very fast, up to 30,000 rpm, so they can push a lot of air too. Most CPAP turbines are run on three phase motors, which is why they have three wires going into them to drive them. Most printer motherboards don't have any built in 3 phase controllers, so you need a separate (BLDC) controller to drive 3 phase motors. Additionally, some CPAP motors have hall effect sensors, which accounts for the additional three wires coming out of the motor. This measures the position of the rotor at any given time, which helps with speed control at low RPMs.

Now for the controller to control the speed, they do often include an analogue dial for manual control. But this can be ignored, and unplugged, when setting this up to control from an MCU. There will be a data/signal/PWM pin (5v/3.3v) on the controller, which you would connect with a corresponding PWM capable pin on the MCU. Don't confuse PWM fan pins with PWM data pins though. Fan pins are controlled load pins on the receiving end of mosfets, so will not work for this.

 

[Durahl]

Hi,
I came across this looking for a solution for another problem, but thought I could offer some info.

CPAP fans are not so much fans as turbines. Unlike a radial fan, they focus mostly on pressure than airflow. Though the turbines in CPAPs spin very fast, up to 30,000 rpm, so they can push a lot of air too. Most CPAP turbines are run on three phase motors, which is why they have three wires going into them to drive them. Most printer motherboards don't have any built in 3 phase controllers, so you need a separate (BLDC) controller to drive 3 phase motors. Additionally, some CPAP motors have hall effect sensors, which accounts for the additional three wires coming out of the motor. This measures the position of the rotor at any given time, which helps with speed control at low RPMs.

Now for the controller to control the speed, they do often include an analogue dial for manual control. But this can be ignored, and unplugged, when setting this up to control from an MCU. There will be a data/signal/PWM pin (5v/3.3v) on the controller, which you would connect with a corresponding PWM capable pin on the MCU. Don't confuse PWM fan pins with PWM data pins though. Fan pins are controlled load pins on the receiving end of mosfets, so will not work for this.

Thanks for the insight!

I've since come across a guide as to how to wire and configure one up - Though I have not yet started working on it as I have yet to finalize my concept on how I integrate it into my System.