Patent Application
20090104016
This application claims the benefit of priority based on China Patent Application No. 200710124058.7 filed on Oct. 22, 2007, the contents of which are incorporated herein by reference in their entirety.
Not applicable.
1. Field of the Invention
The present invention relates to a control circuit and a fan comprising the same. More specifically, the present invention relates to a control circuit capable of adjusting an impedance value in response to an environmental temperature and a fan comprising the same.
2. Descriptions of the Related Art
With the continual development of electronic technologies, more heat is generated by the central processing unit (CPU) and other electronic elements within the computers. Accordingly, stricter requirements have been imposed on the heat dissipation so that the various electronic elements can operate normally under high power and high heat. Generally, one common way to dissipate heat is to provide an additional cooling fan, which is operated by a driving apparatus that rotates at a high speed for quick heat dissipation. On the other hand, to decrease the power consumption of the cooling fan and prolong the service life of the driving apparatus, the driving apparatus is configured to decrease the rotational speed of the cooling fan when the electronic elements operate in a low power mode with much less heat generation.
Conventionally, the driving apparatuses typically employ pulse width modulation (PWM) technology to adjust the rotational speed of the cooling fan. This technology adjusts the rotational speed of the fan by changing the ON and OFF status of the fan in a unit time. Since the typical cooling fans operate at a widely varied rotational speed, the current that the PWM has to adjust also varies widely. Nevertheless, when electronic elements (e.g., a CPU) are generally operated in the lower power mode, the fan has a slower rotational speed to account for the decreased rotational speed. In this case, abrupt variations to the inductor's current induced by the PWM controlling operations will cause considerably loud noise and also increased switching loss.
In summary, it is important to find another means to dynamically adjust the rotational speed of the fan in the driving apparatus in response to the temperature of the electronic elements without incurring additional costs and noise.
One objective of the present invention is to provide a control circuit applied in a fan comprising a plurality of windings. The control circuit is configured to change a connection between these windings in response to an environmental temperature to adjust an impedance value of the fan to change the rotational speed of the fan. The control circuit comprises a temperature sensing module and an adjusting module. The temperature sensing module is configured to sense the environmental temperature to generate a temperature signal. The adjusting module is coupled to the windings and configured to change the connection between the windings in response to the temperature signal to adjust the impedance value of the fan, wherein a rotational speed of the fan is changed according to the impedance value.
Another objective of the present invention is to provide a fan comprising a plurality of windings and a control circuit. The control circuit comprises a temperature sensing module and an adjusting module. The temperature sensing module is configured to sense an environmental temperature to generate a temperature signal. The adjusting module is coupled to the windings and configured to change a connection between the windings in response to the temperature signal to adjust an impedance value of the fan, wherein a rotational speed of the fan is changed according to the impedance value.
The present invention adjusts the impedance value of the fan by changing the connection between a plurality of windings via the temperature sensing module and adjusting module. Once the impedance value of the fan is changed, the rotational speed of the fan can be adjusted. This will eliminate the loud noise and increased switching loss caused by the abrupt variation to the inductor's current in the conventional PWM controlling method.
The detailed technology and preferred embodiments implemented for the subject invention are described in the following paragraphs accompanying the appended drawings for people skilled in this field to well appreciate the features of the claimed invention.
The following embodiments will be described to explain the present invention. The present invention relates to a control circuit and a fan comprising the same. The control circuit is configured to sense an environmental temperature and to change a connection between a plurality of windings in the fan in response to the sensed temperature. The impedance value of the fan is then changed to adjust the rotational speed of the fan. In this way, the present invention effectively prevents the problems of the conventional solutions. However, these embodiments are not intended to limit the present invention to any specific context, applications or particular methods described in these embodiments. Therefore, the description of these embodiments is only intended to illustrate rather than to limit the present invention. It should be noted that in the following embodiments and drawings, the elements not directly related to the present invention are omitted from depiction. Dimensional relationships among individual elements are illustrated only for understanding rather than that to limit the actual scale thereto.
A first embodiment of the present invention is a fan 1 as shown in
When the environment temperature decreases, the first adjusting signal 132 from the adjusting module 133 will turn off the first switch element 14 while the second adjusting signal 134 from the adjusting module 133 will turn on the second switch element 15. The first winding 11 and the second winding 12 are electrically connected in series through the second switching element 15. At this point, the first winding 11 and the second winding 12 will jointly yield an impedance value, which is greater than the impedance value yielded by the first winding 11 solely. For example, assuming that both the first winding 11 and the second winding 12 have an impedance value of 2 ohms (Ω), when the first switch element 14 is turned on and the second switch element 15 is turned off, the fan 1 has an impedance value of 2Ω. In contrast, when the first switch element 14 is turned off and the second switch element 15 is turned on instead, the first winding 11 and the second winding 12 will be electrically connected in series and yield an overall impedance value of 4Ω. As the overall impedance value of the fan 1 is increased, the rotational speed of the fan 1 is decreased. As a result, the power consumption of the fan 1 will decrease.
When the rotational speed of the fan 1 needs to be increased again, the adjusting module 133 changes the first adjusting signal 132 and the second adjusting signal 134 to turn on the first switch element 14 and turn off the second switch element 15. In this way, the rotational speed of the fan 1 can be controlled in response to the on or off status of the first switch element 14 and second switch element 15.
In this embodiment, the first switch element 14 and the second switch element 15 may be Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFET). Connections between the MOSFETs and the first winding 11 and the second winding 12 are well-known to those skilled in the art, and thus a detailed description thereof will be omitted herein.
A second embodiment of the present invention is shown in
When the temperature in the environment rises, the second adjusting signal 234 from the adjusting module 233 will turn on the second switch element 25 so that the first winding 21 and the second winding 22 are electrically connected in parallel through the first switch element 24 and the second switching element 25 which are both turned on. At this point, the first winding 21 and the second winding 22 will jointly yield an impedance value, which becomes smaller than the impedance value yielded by the first winding 21 solely. For example, assuming that both the first winding 21 and the second winding 22 have an impedance value of 2Ω, when the first switch element 24 is turned on and the second switch element 25 is turned off, the fan 2 has an impedance value of 2Ω. In contrast, when the first switch element 24 and the second switch element 25 are both turned on in response to the first adjusting signal 232 and the second adjusting signal 234 respectively, the first winding 21 and the second winding 22 will be electrically connected in parallel and yield an overall impedance value of 1Ω. As the overall impedance value of the fan 2 is decreased, the rotational speed of the fan 2 is increased. As a result, the cooling performance of the fan 2 is enhanced.
When the rotational speed of the fan 2 needs to be increased again, the adjusting module 233 changes the first adjusting signal 232 and the second adjusting signal 234 to keep the first switch element 24 turned on and the second switch element 25 turned off. In this way, the rotational speed of the fan 2 can be controlled in response to the on or off status of the first switch element 24 and the second switch element 25.
In this embodiment, the first switch element 24 and the second switch element 25 may be an MOSFET. Connections between the MOSFETs and the first winding 21 and the second winding 22 are well-known to those skilled in the art, and thus a detailed description thereof will be omitted herein.
A third embodiment of the present invention is shown in
When the environment temperature decreases, the first adjusting signal 332 from the adjusting module 333 will turn on the first switch element 34. The second adjusting signal 334 and the third adjusting signal 336 from the adjusting module 333 will turn off the second switch element 35 and the third switch element 36 respectively, so that the first winding 31 and the second winding 32 are electrically connected in series through the first switching element 34. At this point, the first winding 31 and the second winding 32 will jointly yield an impedance value, which is greater than the impedance value yielded by the first winding 31 solely. For example, assuming that both the first winding 31 and the second winding 32 have an impedance value of 2Ω, when the second switch element 35 is turned on, and the first switch element 34 and the third switch element 36 are turned off, the fan 3 has an impedance value of 2Ω. In contrast, when the first switch element 34 is turned on, and the second switch element 35 and the third switch element 36 are turned off, the first winding 31 and the second winding 32 will be electrically connected in series and yield an overall impedance value of 4Ω. Since the overall impedance value of the fan 3 is increased, the rotational speed of the fan 3 is decreased As a result, power consumption of the fan 3 will decrease.
On the other hand, when the environment temperature increases, the second adjusting signal 334 and the third adjusting signal 336 from the adjusting module 333 will turn on the second switch element 35 and the third switch element 36 respectively. The first adjusting signal 332 from the adjusting module 333 will turn off the first switch element 34 so that the first winding 31 and the second winding 32 are electrically connected in parallel through the second switch element 35 and the third switching element 36 which are both turned on. At this point, the first winding 31 and the second winding 32 will jointly yield an impedance value, which is smaller than the impedance value yielded by the first winding 31 solely. For example, assuming that both the first winding 31 and the second winding 32 have an impedance value of 2Ω, when the second switch element 35 is turned on while the first switch element 34 and the third switch element 36 are turned off, the fan 3 has an impedance value of 2Ω. In contrast, when the second switch element 35 and the third switch element 36 are turned on in response to the second adjusting signal 334 and the third adjusting signal 336 respectively, the first winding 31 and the second winding 32 will be electrically connected in parallel and yield an overall impedance value of 1Ω. As the overall impedance value of the fan 3 is decreased, the rotational speed of the fan 3 is increased. As a result, the cooling performance of the fan 3 is enhanced.
In other words, in the third embodiment, the connection between the windings may be either a series connection, parallel connection, or a combination thereof. Through various combinations of the winding connections, a plurality of rotational speed ranges can be defined by different winding connection.
In this embodiment, the first switch element 34, the second switch element 35 and the third switch element 36 may be a MOSFET. Connections between the MOSFETs and the first winding 31 and the second winding 32 are well-known to those skilled in the art, and thus a detailed description thereof will be omitted herein.
Furthermore, in each of the rotational speed ranges defined by the changing overall impedance value of the windings, the fine tuning of the rotational speed can be further accomplished by the adjusting module 333 through pulse width modulation (PWM), which is well-known to those skilled in the art and thus will not be described in detail again.
In summary, the present invention can use a temperature sensing module and an adjusting module to adjust the overall impedance value of a fan by changing the connection between the windings. The change of the impedance value will lead to an adjustment of the rotational speed of the fan to obviate the loud noise and increased switching loss caused by the abrupt variation to the inductor's current in the conventional PWM controlling method. Meanwhile, the adjustability of the rotational speed will lead to further decreased power consumption of the fan.
The above disclosure is related to the detailed technical contents and inventive features thereof. People skilled in this field may proceed with a variety of modifications and replacements based on the disclosures and suggestions of the invention as described without departing from the characteristics thereof. Nevertheless, although such modifications and replacements are not fully disclosed in the above descriptions, they have substantially been covered in the following claims as appended.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200710124058.7 | Oct 2007 | CN | national |
