Fan driving circuit capable of realizing wide voltage and constant speed

Abstract

The utility model relates to the technical field of fan drive circuits, and discloses a wide-voltage constant-speed fan drive circuit, which comprises a step-down AC / DC (alternating current / direct current) constant-voltage chip U1, a motor electrically connected with the step-down AC / DC constant-voltage chip U1, a bootstrap booster circuit and an LC (inductance-capacitance) filter circuit, wiring ends of a pin 4 and a pin 5 of the step-down AC / DC constant-voltage chip U1 are connected with anti-reverse-connection diodes D1 connected with 30V-310V input voltage, the bootstrap boost circuit is connected to a pin 3 of the step-down AC / DC constant-voltage chip U1, and the LC filter circuit is electrically connected with the bootstrap boost circuit and a positive electrode of the motor. Through the design of the step-down AC / DC constant-voltage chip U1 and the bootstrap boost circuit, after 30V-310V direct-current voltage is input, the direct-current voltage is supplied to the step-down AC / DC constant-voltage chip U1 and the bootstrap boost circuit after being filtered by the capacitor C1, and then the direct-current voltage is filtered by the LC filter circuit to obtain 24V direct-current voltage, so that the constant rotating speed of the fan can be ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of fan drive circuits, and specifically relates to a fan drive circuit that can achieve constant speed under a wide voltage range. Background Technique

[0002] The fan drive circuit is a key part for controlling the fan speed and providing a stable voltage. When a PWM signal is input into the voltage regulation module, the voltage regulation module adjusts the amplitude of the output voltage according to the duty cycle of the signal. Subsequently, the shaping module shapes the adjusted voltage into direct current and performs a voltage stabilization process through the voltage stabilization module. Finally, the filtering module filters the voltage after voltage stabilization to remove the noise and interference signals in the voltage. After this series of processes, a stable and pure direct current is provided to the fan motor to drive it to operate at a constant speed.

[0003] After retrieval, a patent with the application number CN201010285084.X discloses a fan drive circuit disposed inside an electronic device. The fan drive circuit includes: a control chip that outputs a signal that changes with the temperature inside the electronic device; a signal processing circuit that converts and amplifies the signal output by the control chip and outputs a voltage signal from the output terminal; and a control circuit that includes a zener diode, a triode, and an auxiliary resistor. The base of the triode is connected to the output terminal of the signal processing circuit, the emitter is grounded through the auxiliary resistor, and the collector is connected to the power supply through the fan to drive the fan. The anode of the zener diode is connected between the operational amplifier circuit and the base of the triode, and the cathode is connected between the fan and the collector of the triode.

[0004] Currently, the voltage for driving the fan to rotate is generally less than 50V (5V, 12V, 24V, 48V), and the front-end voltage (input voltage) of the drive circuit for driving the fan to rotate is generally 110V or 220V. After the input AC voltage is rectified and filtered, it needs to be step-down processed to be converted into the voltage required to drive the fan to rotate. If no step-down processing is performed, the output voltage is too high, resulting in an inconsistent fan speed and affecting the stable operation of the fan. Therefore, we need to propose a fan drive circuit that can achieve constant speed under a wide voltage range. Whether the input voltage is 30V or 310V, a constant voltage of 24V is output to ensure a constant fan speed. Content of the Utility Model

[0005] The purpose of the utility model is to provide a fan drive circuit that can achieve constant speed under a wide voltage range. Through the design of a buck-type AC / DC constant voltage chip U1 and a bootstrap boost circuit, after inputting a DC voltage of 30V - 310V, it is filtered by a capacitor C1 and then supplied to the buck-type AC / DC constant voltage chip U1 and the bootstrap boost circuit. After filtering by an LC filter circuit, a DC voltage of 24V is obtained, which can ensure a constant fan speed, so as to solve the problems raised in the above background technique.

[0006] To achieve the above object, the utility model provides the following technical solution: A fan drive circuit capable of constant speed under wide voltage, comprising a buck AC / DC constant voltage chip U1, a motor electrically connected to the buck AC / DC constant voltage chip U1, a bootstrap boost circuit, and an LC filter circuit. An anti-reverse connection diode D1 for connecting an input voltage of 30V - 310V is connected to the connection terminals of pins 4 and 5 of the buck AC / DC constant voltage chip U1. The bootstrap boost circuit is connected to pin 3 of the buck AC / DC constant voltage chip U1, and the LC filter circuit is electrically connected to the positive poles of the bootstrap boost circuit and the motor respectively.

[0007] Preferably, a current limiting resistor R1 is connected between the connection terminals of pins 1 and 2 and pin 6 of the buck AC / DC constant voltage chip U1. A capacitor C1 and a freewheeling diode D3 are connected between the connection terminals of pins 4 and 5 and the connection terminals of pins 1 and 2 of the buck AC / DC constant voltage chip U1.

[0008] Preferably, the bootstrap boost circuit includes a capacitor C5 and a diode D2 connected in parallel to pin 3 of the buck AC / DC constant voltage chip U1. One end of the capacitor C5 is connected to the connection terminals of pins 1 and 2 of the buck AC / DC constant voltage chip U1.

[0009] Preferably, the LC filter circuit includes an inductor L3 and a capacitor C3 respectively connected to one end of the diode D2. One end of the inductor L3 and one end of the capacitor C3 are respectively connected to both ends of the freewheeling diode D3.

[0010] Preferably, a resistor R2 for outputting a 24V voltage is connected in parallel to the capacitor C3. One end of the resistor R2 is connected to the positive pole of the motor, and the negative pole of the motor is grounded.

[0011] Compared with the prior art, the beneficial effects of the utility model are:

[0012] Through the design of the buck AC / DC constant voltage chip U1 and the bootstrap boost circuit, after inputting a DC voltage of 30V - 310V, it is filtered by the capacitor C1 and then supplied to the buck AC / DC constant voltage chip U1 and the bootstrap boost circuit. After being filtered by the LC filter circuit, a DC voltage of 24V is obtained, which can ensure the constant speed of the fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the circuit diagram of the utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0015] Please refer to Figure 1 , the present invention provides a technical solution: a fan drive circuit that can achieve constant speed under a wide voltage, including a buck AC / DC constant voltage chip U1, a motor electrically connected to the buck AC / DC constant voltage chip U1, a bootstrap boost circuit, and an LC filter circuit. An anti-reverse connection diode D1 for connecting a 30V - 310V DC input voltage is connected to the connection terminals of the 4th and 5th pins of the buck AC / DC constant voltage chip U1. The bootstrap boost circuit is connected to the 3rd pin of the buck AC / DC constant voltage chip U1, and the LC filter circuit is electrically connected to the positive poles of the bootstrap boost circuit and the motor respectively.

[0016] The LC filter circuit is used to filter the voltage output from the bootstrap boost circuit. The LC filter circuit utilizes the principle that a capacitor passes high-frequency signals and blocks low-frequency signals, while an inductor passes low-frequency signals and blocks high-frequency signals. For the high-frequency signals that need to be blocked, the method of using a capacitor to absorb and block the inductor is adopted to prevent them from passing through. For the low-frequency signals that are needed, the characteristics of high resistance of the capacitor and low resistance of the inductor are utilized to allow them to pass through.

[0017] In the figure, V+ is a DC voltage input of 30V - 310V. The anti-reverse connection diode D1 can prevent component damage caused by reverse connection. The model of the buck AC / DC constant voltage chip U1 is BP2522X.

[0018] Customers can input 110V or 220V voltage into the circuit, and after rectification and filtering, it can be directly connected to the fan without the need for voltage reduction.

[0019] A current-limiting resistor R1 is connected between the connection terminals of the 1st and 2nd pins and the 6th pin of the buck AC / DC constant voltage chip U1. A capacitor C1 and a freewheeling diode D3 are connected between the connection terminals of the 4th and 5th pins and the connection terminals of the 1st and 2nd pins of the buck AC / DC constant voltage chip U1;

[0020] The capacitor C1 plays a filtering role. The freewheeling diode D3 is a diode used in conjunction with inductive loads. When the current of an inductive load suddenly changes or decreases, a sudden voltage will be generated at both ends of the inductor, which may damage other components. When cooperating with the freewheeling diode D3, its current can change smoothly, avoiding the occurrence of surge voltage.

[0021] The boost circuit includes a capacitor C5 and a diode D2 connected in parallel to the 3rd pin of the buck AC / DC constant voltage chip U1, and one end of the capacitor C5 is connected to the connection terminal of the 1st and 2nd pins of the buck AC / DC constant voltage chip U1.

[0022] The LC filter circuit includes an inductor L3 and a capacitor C3 respectively connected to one end of the diode D2, and one end of the inductor L3 and one end of the capacitor C3 are respectively connected to both ends of the freewheeling diode D3.

[0023] A resistor R2 for outputting a 24V voltage is connected in parallel to the capacitor C3. One end of the resistor R2 is connected to the positive electrode of the motor, and the negative electrode of the motor is grounded.

[0024] The resistor R2 is a dummy load to prevent the no-load voltage from rising.

[0025] In use, V+ is a DC voltage input of 30V - 310V. The diode D1 is a reverse protection diode to prevent damage to components caused by reverse connection. After being filtered by the capacitor C1, it supplies power to the buck AC / DC constant voltage chip U1. The buck AC / DC constant voltage chip U1 is a buck module. The capacitor C5 and the diode D2 form a boost circuit. The resistor R1 is a current-limiting resistor, and the diode D3 is a freewheeling diode. After passing through the LC filter circuit composed of the inductor L3 and the capacitor C3, a 24V DC voltage is obtained. The resistor R2 is a dummy load to prevent the no-load voltage from rising. At this time, whether the input is 30V or 310V, the output voltage of the fan is 24V and constant, so the rotation speed of the fan is also constant.

[0026] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A fan driving circuit capable of wide voltage constant speed, characterized in that: It includes a step-down AC / DC constant voltage chip U1, a motor electrically connected to the step-down AC / DC constant voltage chip U1, a bootstrap boost circuit, and an LC filter circuit. The connection terminals of pins 4 and 5 of the step-down AC / DC constant voltage chip U1 are connected to an anti-reverse diode D1 connected to a 30V-310V input voltage. The bootstrap boost circuit is connected to pin 3 of the step-down AC / DC constant voltage chip U1, and the LC filter circuit is electrically connected to the positive poles of the bootstrap boost circuit and the motor, respectively.

2. The fan driving circuit capable of wide voltage constant speed according to claim 1, characterized in that: A current limiting resistor R1 is connected between the connection terminals of pins 1 and 2 and pin 6 of the step-down AC / DC constant voltage chip U1, and a capacitor C1 and a freewheeling diode D3 are connected between the connection terminals of pins 4 and 5 and pins 1 and 2 of the step-down AC / DC constant voltage chip U1.

3. The fan driving circuit capable of wide voltage constant speed according to claim 1, characterized in that: The bootstrap boost circuit includes a capacitor C5 and a diode D2 connected in parallel to pin 3 of the buck AC / DC constant voltage chip U1. One end of the capacitor C5 is connected to the connection terminals of pins 1 and 2 of the buck AC / DC constant voltage chip U1.

4. The fan driving circuit capable of wide voltage constant speed according to claim 3, characterized in that: The LC filter circuit includes an inductor L3 and a capacitor C3 respectively connected to one end of the diode D2, and one end of the inductor L3 and one end of the capacitor C3 are respectively connected to two ends of the freewheeling diode D3.

5. The fan driving circuit capable of wide voltage constant speed according to claim 4, characterized in that: A resistor R2 outputting a 24V voltage is connected in parallel to the capacitor C3. One end of the resistor R2 is connected to the positive electrode of the motor, and the negative electrode of the motor is grounded.

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