초록

A cooling fan includes a fan, a motor coupled to the fan to drive the fan and a microcontroller. The microcontroller is connected to the motor and is capable of detecting a speed of the fan in real time and maintaining a constant speed of the fan regardless of changes in input voltage.

대표청구항 ▼

What is claimed is: 1. A cooling fan, comprising: a fan; a motor coupled to the fan to drive the fan; a speed sensor to magnetically monitor a fan speed and to generate a speed sensor interrupt; a timer to generate a timer value to capture a time since an occurrence of a preceding speed sensor inte

What is claimed is: 1. A cooling fan, comprising: a fan; a motor coupled to the fan to drive the fan; a speed sensor to magnetically monitor a fan speed and to generate a speed sensor interrupt; a timer to generate a timer value to capture a time since an occurrence of a preceding speed sensor interrupt and the speed sensor interrupt; and a microcontroller, coupled to the motor and to the speed sensor, to receive the speed sensor interrupt and the timer value, to compare the timer value to a reference representative of the fan speed, to modify a duty cycle of a stator signal based on the comparison of the timer value to the reference to create a modified stator signal, and to transmit the modified stator signal to the motor. 2. The cooling fan of claim 1, wherein if the timer value is less than the reference, the duty cycle of the stator signal is decremented by one clock cycle and the timer is reset. 3. The cooling fan of claim 1, wherein if the timer value is greater than the reference, the duty cycle of the stator signal is incremented by one clock cycle and the timer is reset. 4. The cooling fan of claim 1, wherein the speed sensor is a hall sensor. 5. The cooling fan of claim 1, wherein the microcontroller terminates transmission of the modified stator signal if a current flowing through windings of the motor is above a threshold. 6. A cooling fan comprising: a fan; a motor coupled to the fan to drive the fan, wherein a current through a stator drives the motor; a speed sensor to generate a speed sensor interrupt; a timer to generate a timer value to monitor a time since an occurrence of a preceding speed sensor interrupt; a microcontroller, coupled to the motor and to the speed sensor, to receive the speed sensor interrupt and the timer value, to compare the timer value to a reference representative of a fan speed, to modify a duty cycle of a stator signal based on the comparison of the timer value to the reference to create a first modified stator signal and a second modified stator signal, and to transmit the first modified stator signal and the second modified stator signal; a first driving circuit, coupled to the microcontroller, to receive the modified stator signal and to transmit a first driver stator signal; and a second driving circuit, coupled to the microcontroller, to receive the second modified stator signal, and to transmit a second driver stator signal. 7. The cooling fan of claim 6, further including a first field effect transistor (FET) and a second FET to receive the first driver stator signal and to transmit the current through the stator to the motor. 8. The cooling fan of claim 7, further including a third FET and a fourth FET to receive the second driver stator signal and to transmit the current through the stator to the motor. 9. The cooling fan of claim 8, wherein the first FET and the second FET do not transmit current through the stator to the motor at the same time that the third FET and the fourth FET transfer current through the stator to the motor. 10. The cooling fan of claim 6, wherein the speed sensor is a Hall sensor. 11. The cooling fan of claim 6, wherein the microcontroller terminates transmission of the first modified stator signal and the second modified stator signal if a current measurement for windings of the motor is above a threshold value. 12. A method of driving a cooling fan, comprising: driving a fan with a motor; generating a speed sensor interrupt; sensing a fan speed by the speed sensor which is electrically independent of both the motor and a driving circuit; generating a timer value to capture a time since an occurrence of a preceding speed sensor interrupt and the speed sensor interrupt; receiving the speed sensor interrupt and the timer value; comparing the timer value to a reference representative of the fan speed; and modifying a duty cycle of a stator signal based on the comparison of the timer value to the reference to create a modified stator signal, and to transmit a modified stator signal to the motor. 13. The method of claim 12, wherein modifying the duty cycle is decrementing the duty cycle of the stator signal by a clock cycle when the timer value is less than the reference. 14. The method of claim 13, further including resetting the timer value. 15. The method of claim 12, wherein modifying the duty cycle is incrementing the duty cycle of the stator signal by a clock cycle when the timer value is greater than the reference. 16. The method of claim 15, further including resetting the timer value. 17. The method of claim 12, wherein the speed sensor is a hall sensor. 18. The method of claim 12, wherein the microcontroller terminates transmission of the modified stator signal if a current flowing through windings of the motor is above a threshold. 19. A method of driving a cooling fan, comprising: driving a fan with a motor; generating a speed sensor interrupt; generating a timer value to capture a time since an occurrence of a preceding speed sensor interrupt and the speed sensor interrupt; receiving the speed sensor interrupt and the timer value at a microcontroller; comparing the timer value to a reference representative of a fan speed; modifying a duty cycle of a stator signal based on the comparison of the timer value to the reference to create a first modified stator signal and a second modified stator signal; and transmitting the first modified stator signal to first driving circuit and transmitting the second modified stator signal to a second driving circuit. 20. The method of claim 19, wherein modifying the duty cycle is decrementing the duty cycle by a clock cycle when the timer value is less than the reference. 21. The method of claim 19, wherein modifying the duty cycle is incrementing the duty cycle by a clock cycle when the timer value is greater than the reference. 22. The method of claim 19, further including receiving the first modified stator signal, at a first driving circuit, and transmitting a first driver stator signal and receiving the second modified stator signal, at a second driving circuit, and transmitting a second driver stator signal. 23. The method of claim 19, wherein the speed sensor is a hall sensor. 24. The method of claim 19, wherein the microcontroller terminates transmission of the first modified and the second modified stator signal if a current flowing through windings of the motor is above a threshold.