System and method for controlling forward/reverse rotation of fan

Patent metadata

Field	Value
Publication number	US-9903381-B2
Application number	US-201614991709-A
Country	US
Kind code	B2
Filing date	Jan 8, 2016
Priority date	Feb 13, 2015
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

A control system includes a motor, an interface circuit, a motor controller and a detection control circuit. The interface circuit receives and converts a pulse width modulation signal. The fan dissipates heat when the motor is operated in a forward rotation mode and eliminates dust when the motor is operated in a reverse rotation mode. The detection control circuit reads a duty cycle of the converted pulse width modulation signal in real time. When the motor is operated in the forward rotation mode, the detection control circuit drives the motor controller to control the rotation speed of the fan according to the duty cycle. If the duty cycle is lower than or equal to a first threshold value, the detection control circuit drives the motor controller to switch operation mode of the motor from the forward rotation mode to the reverse rotation mode.

First claim

What is claimed is:

1. A control system for controlling forward/reverse rotation of a fan of an electronic device, the control system comprising:
a motor for driving rotation of the fan;
an interface circuit for receiving and converting a pulse width modulation signal;
a motor controller electrically connected with the motor for controlling a rotation speed of the motor and controlling the motor to be operated in a forward rotation mode or a reverse rotation mode, wherein the fan is forwardly rotated to dissipate heat when the motor is operated in the forward rotation mode, and wherein the fan is reversely rotated to eliminate dust when the motor is operated in the reverse rotation mode; and
a detection control circuit electrically connected with the interface circuit and the motor controller for reading a duty cycle of the converted pulse width modulation signal in real time, wherein when the motor is operated in the forward rotation mode, the detection control circuit drives the motor controller to control the rotation speed of the fan according to the duty cycle, and the detection control circuit double-checks whether the duty cycle is lower than or equal to a first threshold value, wherein if the duty cycle is lower than or equal to the first threshold value, the detection control circuit drives the motor controller to switch operation mode of the motor from the forward rotation mode to the reverse rotation mode.

2. The control system according to claim 1 , wherein the motor controller controls the motor to be operated in the forward rotation mode when the control system is started.

3. The control system according to claim 1 , wherein when the motor is in the reverse rotation mode, the detection control circuit further double-checks whether the duty cycle is higher than or equal to a second threshold value, wherein if the duty cycle is higher than or equal to the second threshold value, the detection control circuit drives the motor controller to switch operation mode of the motor from the reverse rotation mode to the forward rotation mode.

4. The control system according to claim 1 , wherein the rotation speed of the motor in the reverse rotation mode is fixed at 3000 RPM.

5. The control system according to claim 1 , wherein the detection control circuit further comprises a time counter for counting time.

6. The control system according to claim 5 , wherein when the motor is operated in the reverse rotation mode, the detection control circuit drives the motor controller to rotate the motor for a predetermined reverse time period according to a time length counted by the time counter.

7. The control system according to claim 5 , wherein when the motor is operated in the forward rotation mode, the detection control circuit drives the motor controller to rotate the motor for a predetermined forward time period according to a time length counted by the time counter.

8. The control system according to claim 1 , further comprising:
a frequency simulation circuit electrically connected with the detection control circuit, wherein while the motor is operated in the forward rotation mode or the reverse rotation mode, the frequency simulation circuit is disabled, wherein while the motor is in an inertia stop state, the frequency simulation circuit issues a simulated frequency signal to the electronic device; and
a frequency output circuit electrically connected with the motor controller and the detection control circuit, wherein while the motor is operated in the forward rotation mode or the reverse rotation mode, an actual frequency signal corresponding to the rotation speed of the motor is outputted from the frequency output circuit to the electronic device through the detection control circuit and the frequency simulation circuit, wherein while the motor is in the inertia stop state, the frequency output circuit stops outputting the actual frequency signal.

9. The control system according to claim 8 , wherein after the actual frequency signal has not been outputted from the frequency output circuit, and after the actual frequency signal is not outputted from the frequency output circuit for a specified time period or the rotation speed of the motor is higher than a specified rotation speed, the frequency output circuit outputs the actual frequency signal again, wherein the specified time period is larger than or equal to a time interval when the motor is in the inertia stop state.

10. The control system according to claim 8 , wherein the simulated frequency signal is a frequency signal corresponding to a specified rotation speed of the motor, wherein the specified rotation speed of the motor is 500 RPM.

11. A control method for a control system, the control system controlling a fan of an electronic device according to a pulse width modulation signal outputted from the electronic device, the control system comprising a motor for rotating the fan, the control method comprising steps of:
(a) starting the control system;
(b) controlling the motor to be operated in a forward rotation mode;
(c) double-checking whether a duty cycle of the pulse width modulation signal is lower than or equal to a first threshold value;
(d) if the duty cycle of the pulse width modulation signal is lower than or equal to the first threshold value in the step (c), switching operation mode of the motor from the forward rotation mode to a reverse rotation mode;
(e) double-checking whether the duty cycle of the pulse width modulation signal is higher than or equal to a second threshold value;
(f) if the duty cycle of the pulse width modulation signal is not higher than or equal to the second threshold value in the step (e), judging whether the motor has been operated in the reverse rotation mode for a predetermined reverse time period; and
(g) if the motor has been operated in the reverse rotation mode for a predetermined reverse time period in the step (f), performing the step (b) again.

12. The control method according to claim 11 , wherein while operation mode of the motor is switched from the forward rotation mode to the reverse rotation mode in the step (d), a simulated frequency signal that simulates a specified rotation speed of the motor is transmitted from the control system to the electronic device.

13. The control method according to claim 11 , wherein if the duty cycle of the pulse width modulation signal is not lower than or equal to the first threshold value in the step (c), the step (b) is performed again.

14. The control method according to claim 13 , wherein the step (c) comprises sub-steps of:
(c1) repeatedly reading the duty cycle of the pulse width modulation signal at a detecting time interval;
(c2) judging whether the duty cycle of the pulse width modulation signal is lower than or equal to the first threshold value at a first read time;
(c3) if the duty cycle of the pulse width modulation signal is lower than or equal to the first threshold value in the sub-step (c2), judging whether the duty cycle of the pulse width modulation signal is lower than or equal to the first threshold value at a second read time; and
(c4) if the duty cycle of the pulse width modulation signal is lower than or equal to the first threshold value in the sub-step (c3), judging whether the duty cycle of the pulse width modulation signal at the first read time and the duty cycle of the pulse width modulation signal at the second read time are both lower than or equal to the first threshold value,
wherein if a judging result of the sub-step (c4) is satisfied, the step (d) is performed.

15. The control method according to claim 14 , wherein if a ju

Assignees

• Delta Electronics Inc

Inventors

• Liu Cheng Chieh
• Su Chin Ping
• Su Te Sheng
• Wang Wen Chih

Classifications

• H02P6/30

  Arrangements for controlling the direction of rotation (H02P6/22 takes precedence) · CPC title

• F04D19/005

  reversible fans · CPC title

• F04D25/08

  the working fluid being air, e.g. for ventilation · CPC title

• F04D27/004 Primary

  by varying driving speed · CPC title

• Y02B30/70

  Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating · CPC title