CN116480607A - fan drive circuit - Google Patents

Abstract

The present disclosure relates to a fan driving circuit. The fan driving circuit includes: a voltage regulating module, used to adjust the high-level voltage of the input PWM signal to a predetermined reference voltage; a shaping module, connected to the voltage regulating module, used to shape the voltage output by the voltage regulating module into direct current; a voltage stabilizing module, connected to the shaping module, used to stabilize the voltage output by the shaping module; a filter module, connected to the voltage stabilizing module, used to filter the output voltage of the voltage stabilizing module and provide it to the fan. For the fan driving circuit of the present disclosure, PWM signals with different duty ratios are input, and after voltage stabilization control, a corresponding constant power supply voltage is output to the fan, thereby realizing constant voltage multi-stage control of the fan. The present disclosure can quickly and accurately adjust the speed of the fan while providing constant voltage to the fan by inputting a PWM signal.

Description

fan drive circuit

technical field

The present disclosure relates to the technical field of electronic circuits, and in particular, relates to a fan drive circuit.

Background technique

As the function integration of vehicle infotainment system becomes higher and higher, the problem of heat dissipation becomes more and more important. In some vehicles, cooling fans are introduced to provide air cooling to solve the problem of heat dissipation. For the high-speed DC motor of the fan, a constant-voltage drive with a relatively small voltage (for example, less than 5V) is required, and it is best to be able to regulate the speed of the fan in multiple stages.

In the related art, a Low Dropout Regulator (LDO) integrated circuit chip is used to drive the fan at a constant voltage, but the design cost is expensive, and there is no better solution for the multi-level speed regulation function of the fan.

Contents of the invention

The purpose of the present disclosure is to provide a fan driving circuit with multi-level speed regulation function and capable of constant voltage driving.

In order to achieve the above object, the present disclosure provides a fan drive circuit, the fan drive circuit includes:

A voltage regulation module, configured to adjust the high-level voltage of the input pulse width modulation PWM signal to a predetermined reference voltage;

A shaping module, connected to the voltage regulating module, for shaping the voltage output by the voltage regulating module into direct current;

A voltage stabilizing module, connected to the shaping module, for stabilizing the voltage output by the shaping module;

The filtering module is connected with the voltage stabilizing module, and is used for filtering the voltage output by the voltage stabilizing module and providing it to the fan.

Optionally, the voltage regulation module includes a first transistor, a second transistor, a third transistor, a first resistor, a second resistor, a third resistor, and a fourth resistor, wherein the emitter of the first transistor is connected to the power supply, the base of the first transistor is connected to the collector of the second transistor, the collector of the first transistor is connected to the collector of the third transistor through the fourth resistor, the ground wire of the third resistor is connected to the base of the third transistor through the first resistor, and the base of the second transistor is connected to the regulator. The enabling signal end of the voltage regulating module, the emitter ground wire of the second triode, the base of the third triode connected to the PWM signal input end of the voltage regulating module through the second resistor, and the emitter ground wire of the third triode.

Optionally, the shaping module includes a fifth resistor and a first capacitor, one end of the fifth resistor is connected to the output end of the voltage regulation module, the other end of the fifth resistor is grounded through the first capacitor, and the other end of the fifth resistor is used as the output end of the shaping module.

Optionally, the voltage stabilizing module includes:

A voltage feedback submodule, configured to generate a feedback signal according to the output voltage of the voltage stabilizing module;

A signal amplification submodule, connected to the voltage feedback submodule, for amplifying the feedback signal to generate an amplified signal, wherein the signal amplification module includes two transistors of the same type;

A voltage stabilizing and regulating submodule connected to the signal amplifying submodule for stabilizing the voltage according to the amplified signal, and the output voltage of the voltage stabilizing and regulating submodule is used as the output voltage of the voltage stabilizing module;

Wherein, there is a fixed corresponding relationship between the input voltage and the output voltage of the voltage stabilizing module due to the circuit structures in the signal amplification sub-module and the voltage feedback sub-module.

Optionally, the signal amplifying sub-module includes a fourth triode, a fifth triode and a sixth resistor, wherein the fourth triode and the fifth triode are two NPN transistors of the same model, the emitter of the fourth triode is connected to the emitter of the fifth triode, and is grounded through the sixth resistor, the base of the fourth triode is connected to the output end of the shaping module, the collector of the fourth triode is used as the output end of the signal amplification sub-module, and the base of the fifth triode is connected to the voltage feedback sub-module The output terminal of the module, the collector of the fifth triode is connected to the output terminal of the voltage stabilizing and regulating sub-module.

Optionally, the voltage feedback submodule includes a seventh resistor and an eighth resistor, the output terminal of the voltage regulation submodule passes through the eighth resistor and the seventh resistor in sequence, and the node between the eighth resistor and the seventh resistor serves as the output terminal of the voltage feedback submodule.

Optionally, the voltage regulation submodule includes a sixth triode, a ninth resistor, and a second capacitor. The power supply input terminal of the voltage regulation submodule is connected to the output terminal of the shaping module through the ninth resistor and the second capacitor in sequence, and the node between the ninth resistor and the second capacitor is connected to the output terminal of the signal amplification submodule. The collector of the tube is used as the output terminal of the voltage stabilizing module.

Optionally, the filtering module includes a Zener diode and a third capacitor, one end of the third capacitor is connected to the cathode of the Zener diode, the other end of the third capacitor is connected to the anode of the Zener diode, and a ground wire, and the cathode of the Zener diode is connected to the output of the voltage stabilizing module and serves as the output of the filtering module.

Optionally, the models of the fourth triode and the fifth triode are both BC847.

Optionally, the power of the sixth triode is greater than or equal to 250mW.

Through the above technical solution, PWM signals with different duty ratios are input, different DC voltages are generated after the voltage regulation module and the shaping module, and the corresponding constant power supply voltage is output to the fan after voltage stabilization control, thereby realizing the constant voltage multi-level control of the fan. If the fan speed needs to be changed, it is only necessary to control and change the duty ratio of the input PWM signal. The present disclosure can quickly and accurately adjust the speed of the fan while providing a constant voltage to the fan by inputting a PWM signal.

Other features and advantages of the present disclosure will be described in detail in the detailed description that follows.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present disclosure, and constitute a part of the description, together with the following specific embodiments, are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the attached picture:

Fig. 1 is a structural block diagram of a fan driving circuit provided by an exemplary embodiment;

Fig. 2 is a schematic circuit diagram of a fan drive circuit provided by an exemplary embodiment.

Detailed ways

Specific embodiments of the present disclosure will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the present disclosure, and are not intended to limit the present disclosure.

Fig. 1 is a structural block diagram of a fan drive circuit provided by an exemplary embodiment. As shown in FIG. 1 , the fan driving circuit may include a voltage regulating module 10 , a shaping module 20 , a voltage stabilizing module 30 and a filtering module 40 .

The voltage regulating module 10 is used for regulating the high-level voltage of an input pulse width modulation (Pulse Width Modulation, PWM) signal to a predetermined reference voltage.

The shaping module 20 is connected with the voltage regulating module 10, and is used for shaping the voltage output by the voltage regulating module 10 into direct current.

The voltage stabilizing module 30 is connected to the shaping module 20 and used for stabilizing the voltage output by the shaping module 20 .

The filtering module 40 is connected with the voltage stabilizing module 30, and is used for filtering the voltage output by the voltage stabilizing module 30 and providing it to the fan.

Through the above technical solution, PWM signals with different duty ratios are input, different DC voltages are generated after the voltage regulation module and the shaping module, and the corresponding constant power supply voltage is output to the fan after voltage stabilization control, thereby realizing the constant voltage multi-level control of the fan. If the fan speed needs to be changed, it is only necessary to control and change the duty ratio of the input PWM signal. The present disclosure can quickly and accurately adjust the speed of the fan while providing a constant voltage to the fan by inputting a PWM signal.

Fig. 2 is a schematic circuit diagram of a fan drive circuit provided by an exemplary embodiment. This embodiment can be used as a fan constant voltage multi-stage speed regulation circuit in a vehicle infotainment system. The input power VBATT of the fan drive circuit can be the voltage of the vehicle battery, and can output a stable 5V voltage for the external fan.

In the embodiment of FIG. 2 , the voltage regulation module 10 may include a first transistor Q1 , a second transistor Q2 , a third transistor Q3 , a first resistor R1 , a second resistor R2 , a third resistor R3 and a fourth resistor R4 . Wherein, the emitter of the first transistor Q1 is connected to the power supply (VG3V3), the base of the first transistor Q1 is connected to the collector of the second transistor Q2, the collector of the first transistor Q1 (node P2) is connected to the collector of the third transistor Q3 (node P3) through the fourth resistor R4, the ground wire is passed through the third resistor R3, and the base of the third transistor Q3 (node P1) is connected through the first resistor R1. The base of the second transistor Q2 is connected to the enable signal terminal (FAN_EN) of the voltage regulation module 10 , and the emitter of the second transistor Q2 is grounded (GND). The base of the third transistor Q3 is connected to the PWM signal input terminal (FAN_Speed) of the voltage regulating module 10 through the second resistor R2, and the emitter of the third transistor Q3 is grounded.

The enable control signal of the fan driving circuit may be a signal FAN_EN from a motor control unit (MotorControl Unit, MCU) of the vehicle. When FAN_EN is at a high level, the second transistor Q2 is turned on in saturation to ground, and the first transistor Q1 is turned on in saturation, so that the 3.3V voltage of VG3V3 is turned on, and provides pull-up power for the first resistor R1, the third resistor R3 and the fourth resistor R4. The FAN_Speed signal is a PWM signal generated by the MCU, that is, the fan speed control signal. The voltage of VG3V3 is the predetermined reference voltage. The output (node P3) terminal of the voltage regulating module 10 also outputs a PWM signal, the high level is the voltage of VG3V3, which is filtered by the fifth resistor R5 and the first capacitor C1 and then shaped into a DC voltage VP4 at the node P4. By controlling the different duty ratios of the PWM signals, the output voltage value (FAN+) of the back-end voltage regulator module is adjusted, and the fan constant voltage multi-level control is realized.

The shaping module 20 may include a fifth resistor R5 and a first capacitor C1, one end of the fifth resistor R5 is connected to the output end (node P3) of the voltage regulating module 10, the other end of the fifth resistor R5 is grounded (GND) through the first capacitor C1, and the other end of the fifth resistor R5 is used as the output end (node P4) of the shaping module 20.

The voltage stabilization module 30 may include a voltage feedback sub-module, a signal amplification sub-module and a voltage regulation sub-module.

The voltage feedback sub-module is used for generating a feedback signal according to the output voltage of the voltage stabilizing module 30 .

The signal amplification sub-module is connected with the voltage feedback sub-module for amplifying the feedback signal to generate an amplified signal. Wherein, the signal amplification module includes two transistors of the same type.

The voltage stabilizing and regulating sub-module is connected with the signal amplifying sub-module for stabilizing the voltage according to the amplified signal, and the output voltage of the voltage stabilizing and regulating sub-module is used as the output voltage of the voltage stabilizing module 30 .

Wherein, there is a fixed corresponding relationship between the input voltage and the output voltage of the voltage stabilizing module 30 due to the circuit structures in the signal amplification sub-module and the voltage feedback sub-module.

Wherein, the signal amplifying sub-module may include a fourth transistor Q4, a fifth transistor Q5 and a sixth resistor R6. Wherein, the fourth transistor Q4 and the fifth transistor Q5 are two NPN transistors of the same type. For example, the models of the fourth triode Q4 and the fifth triode Q5 are both BC847.

The emitter of the fourth triode Q4 is connected to the emitter of the fifth triode Q5 (node P7), and is grounded through the sixth resistor R6, the base of the fourth triode Q4 is connected to the output terminal of the shaping module 20 (node P4), the collector of the fourth triode Q4 (node P5) is used as the output terminal of the signal amplification sub-module, the base of the fifth triode Q5 (node P8) is connected to the output terminal of the voltage feedback sub-module, and the collector of the fifth triode Q5 (node P6) is connected to the voltage regulator Regulates the output of the submodule.

The voltage feedback sub-module may include a seventh resistor R7 and an eighth resistor R8. The output terminal (node P6) of the voltage regulation sub-module passes through the ground wire of the eighth resistor R8 and the seventh resistor R7 in turn, and the node between the eighth resistor R8 and the seventh resistor R7 serves as the output terminal (node P8) of the voltage feedback sub-module.

The seventh resistor R7 and the eighth resistor R8 should follow the formula Vout=VP8/(r7/(r7+r8)), for example, when VP8 is 2V and the Vout target is 5V, then 5=2/(r7/(r7+r8)), when the resistance value r8 of the eighth resistor R8 is 15Kohm, the resistance value r7 of the seventh resistor R7 must be 10Kohm.

Since the emitters of the fourth transistor Q4 and the fifth transistor Q5 are both connected to the node P7, the emitter voltages of the fourth transistor Q4 and the fifth transistor Q5 are equal, ie Ve_Q5=Ve_Q4. Because the base-to-emitter PN junction voltages of the transistors of the same type are approximately equal, Vbe_Q5=Vbe_Q4, so when the fourth transistor Q4 and the fifth transistor Q5 are of the same type, the base voltages of the fourth transistor Q4 and the fifth transistor Q5 are guaranteed to be equal, that is, Vb_Q5=Vb_Q4. The DC voltage VP4 at the node P4 filtered by the fifth resistor R5 and the first capacitor C1 can be adjusted by adjusting the duty cycle of the FAN_Speed signal. According to VP4=VP8, Vout=VP8/(R7/(R7+R8)), the Vout value is obtained, which is the constant voltage value output by FAN+.

In addition, the dual triode structure of the fourth triode Q4 and the fifth triode Q5 having the same type can be used to suppress the temperature drift of the triode parameters.

The voltage regulation sub-module may include a sixth transistor Q6, a ninth resistor R9 and a second capacitor C2. The power supply input terminal (VBATT) of the voltage stabilizing regulation sub-module is connected to the output terminal (node P4) of the shaping module 20 through the ninth resistor R9 and the second capacitor C2 in turn, the node between the ninth resistor R9 and the second capacitor C2 is connected to the output terminal of the signal amplification sub-module (node P5), and the sixth transistor Q6 is a PNP transistor. The emitter of the sixth triode Q6 is connected to the power input terminal (VBATT) of the voltage stabilizing module 30, the base of the sixth triode Q6 is connected to the output terminal (node P5) of the signal amplification sub-module, and the collector of the sixth triode Q6 is used as the output terminal (node P6) of the voltage stabilizing module 30.

In Fig. 2, the operating range of the VBATT input voltage is 9V ~ 16V, and the design target output VOUT voltage is constant. Using the instantaneous polarity method analysis, assuming that the current VBATT input voltage is V1, when the input voltage suddenly increases and is greater than V1, the voltage VP8 fed back to the node P8 by the voltage division of the seventh resistor R7 and the eighth resistor R8 in the voltage feedback sub-module will increase.

Since the value of the voltage Vbe_Q5 from the base to the emitter of the fifth transistor Q5 is fixed, the voltage VP7 at the node P7 increases. Since the fourth transistor Q4 and the fifth transistor Q5 share the emitter, the emitter voltage Ve_Q4 of the fourth transistor Q4 increases. Since the voltage VP8 of the node P8 (ie, the base voltage of the fifth transistor Q5 ) remains constant, the base-to-emitter voltage of the fourth transistor Q4 is Vbe_Q4=VP4-Ve_Q4, so Vbe_Q4 decreases.

According to the input transfer characteristic of the transistor, the decrease of Vbe_Q4 leads to the decrease of the base current Ib_Q4 of the fourth transistor Q4. According to the output characteristic of the transistor, the decrease of Ib_Q4 leads to the increase of the collector-to-emitter voltage Vce_Q4 of the fourth transistor Q4. The increase of Vce_Q4 causes the current IR6 in the sixth resistor R6 to decrease, that is, the base current Ib_Q6 of the sixth transistor Q6 decreases.

For the sixth transistor Q6, according to the output characteristics of the transistor, the voltage Vec_Q6 from the emitter to the collector of the sixth transistor Q6 increases due to the decrease of the base current Ib_Q6 of the sixth transistor Q6. Because Vout=VBATT-Vec_Q6, because Vec_Q6 increases, Vout decreases through negative feedback. The ultimate goal is to adjust the voltage Vec_Q6, thereby realizing the voltage stability of Vout. In this process, the sixth transistor Q6 working in the amplification region realizes the regulation of negative feedback by dynamically adjusting the voltage Vec_Q6 from the emitter to the collector.

Since the sixth triode Q6 has to withstand relatively large power, it is safer to select a triode with a power greater than or equal to 250mW. The 250mW power triode, when its output voltage is 5V, allows a maximum current of 500mA, which is greater than the maximum current of all fans currently on the market.

The filter module 40 may include a Zener diode D1 and a third capacitor C3. One end of the third capacitor C3 is connected to the cathode of the Zener diode D1, and the other end of the third capacitor C3 is connected to the anode of the Zener diode D1 and grounded.

As shown in FIG. 2 , the fan can output a rotational speed feedback signal (FAN_Speed_FB) to the MCU (not shown). A control strategy for the fan rotational speed can be pre-stored in the MCU. According to the fan rotational speed obtained in real time and the strategy, the fan drive circuit can output the PWM signal (FAN_Speed) required for the next step.

The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure. These simple modifications all belong to the protection scope of the present disclosure.

In addition, it should be noted that the various specific technical features described in the above specific implementation manners may be combined in any suitable manner if there is no contradiction. In order to avoid unnecessary repetition, various possible combinations are not further described in this disclosure.

In addition, various implementations of the present disclosure can be combined arbitrarily, as long as they do not violate the idea of the present disclosure, they should also be regarded as the content disclosed in the present disclosure.

Claims (10)

1. A fan drive circuit, characterized in that the fan drive circuit comprises: A voltage regulation module, configured to adjust the high-level voltage of the input pulse width modulation PWM signal to a predetermined reference voltage; A shaping module, connected to the voltage regulating module, for shaping the voltage output by the voltage regulating module into direct current; A voltage stabilizing module, connected to the shaping module, for stabilizing the voltage output by the shaping module; The filtering module is connected with the voltage stabilizing module, and is used for filtering the voltage output by the voltage stabilizing module and providing it to the fan. 2. The fan driving circuit according to claim 1, wherein the voltage regulation module comprises a first triode, a second triode, a third triode, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein the emitter of the first triode is connected to the power supply, the base of the first triode is connected to the collector of the second triode, the collector of the first triode is connected to the collector of the third triode through the fourth resistor, the ground wire of the third resistor is connected, and the base of the third triode is connected to the first resistor. pole, the base of the second triode is connected to the enable signal end of the voltage regulating module, the emitter of the second triode is grounded, the base of the third triode is connected to the PWM signal input end of the voltage regulating module through the second resistor, and the emitter of the third triode is grounded. 3. The fan driving circuit according to claim 1, wherein the shaping module includes a fifth resistor and a first capacitor, one end of the fifth resistor is connected to the output end of the voltage regulating module, the other end of the fifth resistor is connected to the ground wire of the first capacitor, and the other end of the fifth resistor is used as the output end of the shaping module. 4. The fan driving circuit according to claim 1, wherein the voltage stabilizing module comprises: A voltage feedback submodule, configured to generate a feedback signal according to the output voltage of the voltage stabilizing module; A signal amplification submodule, connected to the voltage feedback submodule, for amplifying the feedback signal to generate an amplified signal, wherein the signal amplification module includes two transistors of the same type; A voltage stabilizing and regulating submodule connected to the signal amplifying submodule for stabilizing the voltage according to the amplified signal, and the output voltage of the voltage stabilizing and regulating submodule is used as the output voltage of the voltage stabilizing module; Wherein, there is a fixed corresponding relationship between the input voltage and the output voltage of the voltage stabilizing module due to the circuit structures in the signal amplification sub-module and the voltage feedback sub-module. 5. The fan driving circuit according to claim 4, wherein the signal amplifying sub-module comprises a fourth triode, a fifth triode and a sixth resistor, wherein the fourth triode and the fifth triode are two NPN transistors of the same model, the emitter of the fourth triode is connected to the emitter of the fifth triode, and the base of the fourth triode is connected to the output terminal of the shaping module through the ground wire of the sixth resistor, and the collector of the fourth triode is used as the output terminal of the signal amplification sub-module, The base of the fifth triode is connected to the output end of the voltage feedback sub-module, and the collector of the fifth triode is connected to the output end of the voltage regulation sub-module. 6. The fan drive circuit according to claim 4, wherein the voltage feedback sub-module includes a seventh resistor and an eighth resistor, the output terminal of the voltage regulation sub-module passes through the eighth resistor and the seventh resistor grounding line in sequence, and the node between the eighth resistor and the seventh resistor serves as the output terminal of the voltage feedback sub-module. 7. The fan driving circuit according to claim 4, wherein the voltage stabilizing regulation submodule comprises a sixth triode, a ninth resistor and a second capacitor, the power supply input terminal of the voltage stabilizing regulating submodule is connected to the output terminal of the shaping module through the ninth resistor and the second capacitor in sequence, the node between the ninth resistor and the second capacitor is connected to the output terminal of the signal amplification submodule, the sixth triode is a PNP type triode, the emitter of the sixth triode is connected to the power input terminal of the voltage stabilizing module, and the base of the sixth triode is connected to The output terminal of the signal amplifying sub-module, and the collector of the sixth triode serve as the output terminal of the voltage stabilizing module. 8. The fan driving circuit according to claim 1, wherein the filtering module comprises a voltage stabilizing diode and a third capacitor, one end of the third capacitor is connected to the cathode of the Zener diode, the other end of the third capacitor is connected to the anode of the Zener diode, and a ground wire, and the cathode of the Zener diode is connected to the output end of the voltage stabilizing module and serves as the output end of the filtering module. 9 . The fan driving circuit according to claim 5 , wherein the models of the fourth triode and the fifth triode are both BC847. 10. The fan driving circuit according to claim 7, wherein the power of the sixth triode is greater than or equal to 250mW.