TWI734579B - Fan drive circuit with temperature compensation - Google Patents

Abstract

A fan drive circuit with temperature compensation includes a power input terminal, a power output terminal connected to a fan motor, a first transistor arranged between the power input terminal and the power output terminal, and a first transistor connected to the first power output terminal. The transistor is also connected with a signal adjusting component of a signal generating circuit, a second transistor connected with the signal adjusting component, and a feedback unit. The feedback unit includes a first resistor and a second resistor connected in series, and a compensation bypass of the first resistor or the second resistor in parallel. The compensation bypass includes a thermistor, and the thermistor varies with temperature. The resulting change in resistance value changes the magnitude of a feedback current provided to the second transistor to compensate for the change in the common emitter current gain of the second transistor due to temperature.

Description

Fan drive circuit with temperature compensation

The invention relates to a fan drive circuit, in particular to a fan drive circuit that compensates for changes in the common emitter current gain of a transistor based on temperature changes.

Transistor components all have operating characteristics, and the operating characteristics will vary according to different working environments. Please refer to Figure 1. The figure shows a common emitter current gain (common emitter current gain, abbreviated as hFE or hFE) at different temperatures. β) Schematic diagram of the change. It can be clearly understood from Figure 1 that the higher the working environment temperature of the transistor element, the higher the common emitter current gain will increase.

In today's fan control technology, although many technologies have proposed technical solutions to change the fan speed in response to the ambient temperature, such as TW I686541, etc., the focus of these technologies is that the increase in ambient temperature needs to increase the fan speed to deal with, ignoring the generation of the transistor components. The change of the characteristics of the fan caused the fan control to not meet expectations.

The main purpose of the present invention is to solve the problem that the conventional fan drive circuit does not perform temperature compensation for the associated transistor, and the control does not meet expectations.

To achieve the above objective, the present invention provides a temperature-compensated fan drive circuit, which includes an electric power input terminal, an electric power output terminal connected to a fan motor, and a first electric power output terminal arranged between the electric power input terminal and the electric power output terminal. Transistor, a signal adjusting part, a second transistor connected to the signal input terminal, and a feedback unit. The signal adjusting component has a signal input terminal connected to a signal generating circuit to receive a pulse width modulation signal, a reference voltage input terminal, and a signal output terminal connected to the first transistor. The signal adjusting component is based on the pulse The wave width modulation signal generates a fan driving signal, and the fan driving signal is provided to the first transistor from the signal output terminal. The feedback unit includes a first resistor connected to the power output terminal, a second resistor connected in series with the first resistor, a node between the first resistor and the second resistor and connected to the second transistor, and A compensation bypass that connects the first resistor or the second resistor in parallel. The compensation bypass is composed of a thermistor and a third resistor connected in series with the thermistor. The resistance of the thermistor changes with temperature. The magnitude of a feedback current provided by the node to the second transistor is changed to compensate for the change in the common emitter current gain of the second transistor due to temperature.

In one embodiment, the compensation bypass is connected in parallel with the first resistor, and the thermistor is a positive temperature coefficient thermistor.

In one embodiment, the compensation bypass is connected in parallel with the second resistor, and the thermistor is a negative temperature coefficient thermistor.

In one embodiment, the first transistor is a PNP type bipolar transistor, and the second transistor is an NPN type bipolar transistor.

In one embodiment, the fan driving circuit further includes a fourth resistor provided between the first transistor and the signal adjusting element, and a first emitter and a first base connected to the first transistor. The fifth resistance of the pole.

In one embodiment, one end of the second resistor that is not connected to the node is grounded. In one embodiment, the fan driving circuit further includes a sixth resistor, one end of the sixth resistor is connected to a second emitter of the second transistor, and the other end is grounded.

In one embodiment, the signal adjusting component is a comparator.

In one embodiment, the fan driving circuit includes a seventh resistor electrically connected to the signal generating circuit and the second transistor, and a second capacitor forming an integrating circuit with the seventh resistor.

According to the foregoing disclosure, compared with the conventional technology, the present invention has the following characteristics: the present invention adds the compensation bypass in parallel with the first resistor or the second resistor in the feedback unit, and the compensation bypass The thermistor to which the thermistor belongs in, the resistance of the thermistor will change due to changes in the ambient temperature, so that the feedback current flowing from the feedback unit to the second transistor changes, so as to target the second transistor The change in the common emitter current gain due to temperature is compensated.

The detailed description and technical content of the present invention are described as follows in conjunction with the drawings:

Please refer to FIG. 2, the present invention provides a temperature-compensated fan driving circuit 10, the fan driving circuit 10 does not generate a pulse width modulation signal 30 used to determine the operating speed of a fan, but through a signal generation circuit 31 Obtain the pulse width modulation signal 30. More specifically, in this case, the fan driving circuit 10 uses the pulse width modulation signal 30 from the signal generating circuit 31 to drive the fan, and the fan driving circuit 10 does not involve the signal generating circuit 31 based on the fan The configured ambient temperature adjusts the pulse width modulation signal 30. In addition, the pulse width modulation signal 30 is not directly applied to the fan, but determines how the fan driving circuit 10 drives the fan.

In summary, the fan driving circuit 10 of the present invention includes a power input terminal 11, a power output terminal 12, a first transistor 13, a signal adjustment component 14, a second transistor 15, and a feedback unit 16. The power input terminal 11 obtains power from a power source, the power output terminal 12 is connected to a fan motor 40, and the first transistor 13 is arranged between the power input terminal 11 and the power output terminal 12. In one embodiment, the first transistor 13 is a PNP type bipolar transistor, a first emitter 131 of the first transistor 13 is connected to the power input terminal 11, and a first emitter of the first transistor 13 is The collector 132 is connected to the power output terminal 12. Furthermore, the signal adjusting component 14 has a signal input terminal 141, a reference voltage input terminal 142, and a signal output terminal 143. The signal input terminal 141 is connected to the signal generating circuit 31 to receive the pulse width modulation signal 30, and the reference voltage input terminal 142 is connected to a reference voltage source whose voltage value can be adjusted according to the signal adjustment element 14 Work parameters are selected. In addition, the signal adjuster 14 modulates the received pulse width modulation signal 30 into a fan control signal 32. Here, the purpose of dividing the signal into the pulse width modulation signal 30 and the fan control signal 32 is For specific description, the fan control signal 32 can actually be implemented by pulse width modulation technology. Furthermore, the signal output terminal 143 is connected to the first transistor 13. Specifically, the signal output terminal 143 is connected to a first base electrode 133 of the first transistor 13, and the signal output terminal 143 is connected to the first transistor 13 13 provides the fan control signal 32. The first transistor 13 operates based on the fan control signal 32 to drive the fan motor 40. In one embodiment, the signal adjusting component 14 may be a comparator. Furthermore, the second transistor 15 is connected to the signal input terminal 141 of the signal adjusting component 14 and the feedback unit 16. In one embodiment, the second transistor 15 is an NPN type bipolar transistor, a second collector 152 of the second transistor 15 is electrically connected to the signal input terminal 141, and the second transistor 15 A second base electrode 153 is connected to the feedback unit 16.

2 and 3, the feedback unit 16 of the present invention includes a first resistor 161 connected to the power output terminal 12, a second resistor 162 connected in series with the first resistor 161, and a second resistor 162 located at the first resistor 161 The node 163 of the second transistor 15 is connected to the second resistor 162 and a compensation bypass 164 connected in parallel with the first resistor 161 or the second resistor 162. Wherein, one end of the second resistor 162 that is not connected to the node 163 is grounded. The node 163 of the feedback unit 16 is electrically connected to the second base 153 of the second transistor 15. The compensation bypass 164 is composed of a thermistor 165 and a third resistor 166 connected in series with the thermistor 165. In the embodiment where the compensation bypass 164 is connected in parallel to the first resistor 161, the thermistor 165 is implemented as a positive temperature coefficient thermistor. In the embodiment where the compensation bypass 164 is connected in parallel to the second resistor 162, the thermistor 165 is implemented as a negative temperature coefficient thermistor. Accordingly, the thermistor 165 will change its resistance according to the ambient temperature in the space where the fan driving circuit 10 is configured. Once the thermistor 165 is changed, the magnitude of a feedback current 167 provided by the node 163 to the second base 153 of the second transistor 15 is also changed. The present invention compensates for the change of the common emitter current gain (hFE or β) generated by the second transistor 15 due to temperature by changing the feedback current 167 based on temperature, and solves the problem of conventional circuits. The second transistor 15 changes its characteristics under the influence of temperature, which leads to the problem that the same control parameter produces different control results.

Please refer to FIG. 2 again. In one embodiment, the fan driving circuit 10 further includes a fourth resistor 17 disposed between the first transistor 13 and the signal adjusting component 14, and a fourth resistor 17 connected to the first transistor 13 A fifth resistor 18 between the first emitter 131 and the first base 133. Further, the fan driving circuit 10 may further include a sixth resistor 19, one end of the sixth resistor 19 is connected to a second emitter 151 of the second transistor 15 and the other end is grounded. In addition, in an embodiment, the fan driving circuit 10 has a first capacitor 121 disposed at the power output terminal 12. Furthermore, the fan driving circuit 10 includes a seventh resistor 20 electrically connected to the signal generating circuit 31 and the second collector 152 of the second transistor 15, and a seventh resistor 20 that forms an integrating circuit with the seventh resistor 20 The second capacitor 21. Wherein, the positive terminal of the second capacitor 21 is connected to the second collector 152 of the second transistor 15, and the negative terminal of the second capacitor 21 is connected to the grounded end of the sixth resistor 19. In this embodiment, after the pulse width modulation signal 30 is output from the signal generating circuit 31, it first undergoes the action of the integrating circuit before being combined with the feedback signal of the second transistor 15, and finally enters the signal adjustment A component 14 for the signal adjusting component 14 to generate the fan control signal 32.

In summary, it is only a preferred embodiment of the present invention. When the scope of implementation of the present invention cannot be limited by this, that is, all equal changes and modifications made in accordance with the scope of the patent application of the present invention should still belong to the present invention. The scope of patent coverage.

10: Fan drive circuit 11: Power input 12: Power output 121: first capacitor 13: The first transistor 131: first emitter 132: The first episode 133: first base 14: Signal adjustment 141: Signal input terminal 142: Reference voltage input 143: Signal output terminal 15: second transistor 151: second emitter 152: The second episode 153: second base 16: feedback unit 161: first resistance 162: second resistor 163: Node 164: Compensation Bypass 165: Thermistor 166: third resistor 167: feedback current 17: Fourth resistor 18: Fifth resistor 19: Sixth resistor 20: Seventh resistor 21: second capacitor 30: Pulse width modulation signal 31: signal generating circuit 32: Fan control signal 40: fan motor

Figure 1. The characteristic diagram of the working environment temperature of the transistor element and the common emitter current gain. Fig. 2 is a schematic circuit diagram of a fan driving circuit according to the first embodiment of the present invention. Fig. 3 is a schematic circuit diagram of a fan driving circuit according to a second embodiment of the present invention.

10: Fan drive circuit

11: Power input

12: Power output

121: first capacitor

13: The first transistor

131: first emitter

132: The first episode

133: first base

14: Signal adjustment

141: Signal input terminal

142: Reference voltage input

143: Signal output terminal

15: second transistor

151: second emitter

152: The second episode

153: second base

16: feedback unit

161: first resistance

162: second resistor

163: Node

164: Compensation Bypass

165: Thermistor

166: third resistor

167: feedback current

17: Fourth resistor

18: Fifth resistor

19: Sixth resistor

20: Seventh resistor

21: second capacitor

30: Pulse width modulation signal

31: signal generating circuit

32: Fan control signal

40: fan motor

Claims (10)

A fan drive circuit with temperature compensation, including: A power input terminal; A power output terminal, connected to a fan motor; A first transistor arranged between the power input terminal and the power output terminal; A signal adjusting component has a signal input terminal connected to a signal generating circuit to receive a pulse width modulation signal, a reference voltage input terminal and a signal output terminal connected to the first transistor, the signal adjusting component is based on the The pulse width modulation signal generates a fan driving signal, and the fan driving signal is provided by the signal output terminal to the first transistor; A second transistor connected to the signal input terminal; and A feedback unit including a first resistor connected to the power output terminal, a second resistor connected in series with the first resistor, and a node between the first resistor and the second resistor and connected to the second transistor, And a compensation bypass connected in parallel with the first resistor or the second resistor. The compensation bypass consists of a thermistor and a third resistor connected in series with the thermistor. The resistance of the thermistor changes with temperature, The magnitude of a feedback current provided by the node to the second transistor is also changed to compensate for the change in the common emitter current gain of the second transistor due to temperature. The fan driving circuit with temperature compensation according to claim 1, wherein the compensation bypass is connected in parallel with the first resistor, and the thermistor is a positive temperature coefficient thermistor. The fan driving circuit with temperature compensation according to claim 1, wherein the compensation bypass is connected in parallel with the second resistor, and the thermistor is a negative temperature coefficient thermistor. The fan driving circuit with temperature compensation according to any one of claims 1 to 3, wherein the first transistor is a PNP type bipolar transistor, and the second transistor is an NPN type bipolar transistor. The fan drive circuit with temperature compensation according to claim 4, wherein the fan drive circuit further includes a fourth resistor provided between the first transistor and the signal adjustment element, and a fourth resistor connected to the first transistor A first emitter and a first base of the fifth resistor. According to claim 4, the fan driving circuit with temperature compensation, wherein one end of the second resistor that is not connected to the node is grounded. The fan driving circuit with temperature compensation according to claim 5, wherein the fan driving circuit further includes a sixth resistor, one end of the sixth resistor is connected to a second emitter of the second transistor, and the other end is grounded. The fan driving circuit with temperature compensation according to claim 7, wherein the signal adjusting component is a comparator. According to any one of claims 1 to 3, the fan driving circuit with temperature compensation, wherein the signal adjusting component is a comparator. The fan drive circuit with temperature compensation according to any one of claims 1 to 3, wherein the fan drive circuit includes a seventh resistor electrically connected to the signal generating circuit and the second transistor, and a The seven resistors constitute the second capacitor of an integrating circuit.

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