WO2022242037A1

WO2022242037A1 - Power supply circuit, power supply system and smart door lock

Info

Publication number: WO2022242037A1
Application number: PCT/CN2021/126899
Authority: WO
Inventors: 李雪春; 张德建
Original assignee: 北京市商汤科技开发有限公司
Priority date: 2021-05-17
Filing date: 2021-10-28
Publication date: 2022-11-24
Also published as: CN215343977U

Abstract

Provided in the embodiments of the present application are a power supply circuit, a power supply system and a smart door lock. The power supply circuit comprises a power supply battery, an anti-reverse-connection module and a buck-boost module, wherein the power supply circuit is used for supplying power to a facial recognition module; a positive electrode of the power supply battery is connected to a first end of the anti-reverse-connection module, a second end of the anti-reverse-connection module is connected to an input positive electrode of the buck-boost module, and an output positive electrode of the buck-boost module is connected to a positive electrode power supply end of the facial recognition module; a negative electrode of the power supply battery, an input negative electrode of the buck-boost module, an output negative electrode of the buck-boost module and a negative electrode power supply end of the facial recognition module are grounded; when the voltage of the power supply battery is greater than a power supply voltage of the facial recognition module, the buck-boost module works in a buck mode; and when the voltage of the power supply battery is less than the power supply voltage of the facial recognition module, the buck-boost module works in a boost mode. By means of the embodiments of the present application, the endurance time of a facial recognition module can be prolonged.

Description

Power supply circuit, power supply system and smart door lock

This application claims the priority of the Chinese patent application with the application number 202121054444.5 and the application name "power supply circuit, power supply system and intelligent door lock" submitted to the China Patent Office on May 17, 2021, the entire contents of which are incorporated herein by reference Applying.

technical field

The present application relates to the technical field of capacitance control, in particular to a power supply circuit, a power supply system and an intelligent door lock.

Background technique

At present, face recognition technology has gradually become popular in smart door locks, and more and more door lock manufacturers have begun to launch face recognition smart door lock products. Lock security and convenience. The face recognition module has higher requirements for hardware, which is followed by greater power consumption. Most of the current face recognition smart door locks are powered by lithium batteries or dry batteries plus a step-down circuit.

However, the power supply mode of the battery series step-down circuit makes the battery discharge insufficient and the battery life is short.

Contents of the invention

The embodiment of the present application provides a power supply circuit, a power supply system and an intelligent door lock, which can prolong the battery life of the face recognition module.

The first aspect of the embodiments of the present application provides a power supply circuit, including a power supply battery, an anti-reverse connection module, and a buck-boost module, the power supply circuit is used to supply power to the face recognition module, and the anti-reverse connection module is used for cutting off the output of the power supply battery when the positive and negative poles of the power supply battery are reversely connected;

The positive pole of the power supply battery is connected to the first end of the anti-reverse connection module, the second end of the anti-reverse connection module is connected to the input positive pole of the buck-boost module, and the output positive pole of the buck-boost module is connected to the The positive power supply terminal of the face recognition module, the negative pole of the power supply battery, the input negative pole of the buck-boost module, the negative output pole of the buck-boost module, and the negative power supply terminal of the face recognition module are grounded ;

When the voltage of the power supply battery is greater than the power supply voltage of the face recognition module, the buck-boost module works in buck mode; when the voltage of the power supply battery is lower than the face recognition module In the case of supply voltage, the buck-boost module works in boost mode.

The buck-boost module can decide to work in step-down mode or boost mode according to the voltage of the power supply battery and the power supply voltage of the face recognition module, not only when the voltage of the power supply battery is greater than the power supply voltage of the face recognition module Provide power for the face recognition module, and can also supply power for the face recognition module when the voltage of the power supply battery is lower than the power supply voltage of the face recognition module, which can make full use of the power of the power supply battery and extend the battery life of the face recognition module time.

Optionally, the anti-reverse connection module includes a first switch tube, the anode of the parasitic diode of the first switch tube is connected to the anode of the power supply battery, and the cathode of the parasitic diode is connected to the input of the buck-boost module positive electrode.

Wherein, the first switching tube is used as the anti-reverse connection module, which can prevent the entire circuit from being burned out when the power supply battery is reversely connected. Since the working voltage drop of the switching tube is much smaller than that of the diode, the power consumption of the switching tube is lower than that of the diode, which can realize the anti-reverse connection function and significantly reduce power consumption and heat generation.

Optionally, the anti-reverse connection module includes a first diode, the anode of the first diode is connected to the anode of the power supply battery, and the cathode of the first diode is connected to the buck-boost module input positive.

Among them, the use of the first diode as the anti-reverse connection module can prevent the entire circuit from being burned when the power supply battery is reversed, and can be used in scenarios that are not sensitive to power consumption. Compared with the use of switching tubes, the price of diodes is lower , can reduce the cost of the power supply circuit.

Optionally, the buck-boost module includes a control module, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a first capacitor, a second capacitor, and a first inductor;

The first end of the first capacitor is connected to the first end of the second switch tube and the second end of the first switch tube, and the second end of the second switch tube is connected to the fifth switch tube. The first end and the first end of the first inductance, the second end of the first inductance is connected to the first end of the third switching tube and the first end of the fourth switching tube, the third The second end of the switch tube is connected to the first end of the second capacitor and the positive power supply end of the face recognition module, the second end of the first capacitor, the second end of the fourth switch tube, The second terminal of the fifth switch tube and the second terminal of the second capacitor are grounded;

The control module includes a first output interface, a second output interface, a third output interface and a fourth output interface, the first output interface is connected to the control terminal of the second switching tube, and the second output interface is connected to the The control terminal of the third switching tube, the third output interface is connected to the control terminal of the fourth switching tube, the fourth output interface is connected to the control terminal of the fifth switching tube, and the control terminal of the first switching tube The control end is connected to the negative pole of the power supply battery.

Among them, two capacitors are designed at the input and output of the buck-boost module to prevent sudden changes in the input voltage and output voltage of the buck-boost module, so as to ensure that the power supply voltage of the face recognition module will not occur when the buck-boost module switches modes. sudden change, so as to ensure the stable power supply of the face recognition module. The buck-boost module is designed with four switch tubes, and the step-down mode and boost mode are realized by controlling the working status of the four switch tubes. Due to the fast response speed of the switch tubes, the mode switching can be quickly realized, further ensuring that the face recognition module stable power supply.

Optionally, when the voltage of the power supply battery is greater than the power supply voltage of the face recognition module, the control module controls the third switch to be turned on, the fourth switch to be turned off, and the The second switch tube and the fifth switch tube work in the first pulse width modulation PWM mode.

Among them, the buck-boost module can control the status of the second switch tube, the third switch tube, the fourth switch tube and the fifth switch tube, so as to control the buck-boost module to work in the step-down mode, because the response speed of the switch tube is fast , can quickly realize the mode switching, and ensure the stable power supply of the face recognition module.

Optionally, in the first PWM mode, the duty ratio of the first PWM signal sent by the control module to the control terminal of the second switching transistor and the control terminal of the fifth switching transistor;

Wherein, the duty cycle of the first PWM signal is determined according to the ratio of the output anode voltage of the buck-boost module to the input anode voltage of the buck-boost module. The control module can adjust the duty cycle of the first PWM signal at the control terminal of the second switching tube and the control terminal of the fifth switching tube in real time according to the change of the input positive voltage of the buck-boost module, so that the voltage of the buck-boost module The output voltage can be kept stable, thereby ensuring the stable power supply of the face recognition module.

Optionally, when the voltage of the power supply battery is lower than the power supply voltage of the face recognition module, the control module controls the second switch to be turned on, the fifth switch to be turned off, and the The third switch tube and the fourth switch tube work in the second PWM mode.

Among them, the buck-boost module can control the state of the second switch tube, the third switch tube, the fourth switch tube and the fifth switch tube, thereby controlling the buck-boost module to work in the boost mode, because the response speed of the switch tube is fast , can quickly realize the mode switching, and ensure the stable power supply of the face recognition module.

Optionally, in the second PWM mode, the duty ratio of the second PWM signal sent by the control module to the control terminal of the third switching transistor and the control terminal of the fourth switching transistor;

Wherein, the duty ratio of the second PWM signal is determined according to 1 minus the difference between the input positive voltage of the buck-boost module and the positive voltage output of the buck-boost module.

The control module can adjust the duty cycle of the second PWM signal at the control terminal of the third switching tube and the control terminal of the fourth switching tube in real time according to the change of the input positive voltage of the buck-boost module, so that the voltage of the buck-boost module The output voltage can be kept stable, thereby ensuring the stable power supply of the face recognition module.

Optionally, the buck-boost module includes a buck circuit, a boost circuit, a sixth switch tube, and a seventh switch tube;

The second end of the anti-reverse connection module is the first end of the sixth switch tube and the first end of the seventh switch tube, and the second end of the sixth switch tube is connected to the positive side of the step-down circuit. Input terminal, the positive output terminal of the step-down circuit is connected to the positive power supply terminal of the face recognition module; the second terminal of the seventh switching tube is connected to the positive input terminal of the boost circuit, and the boost circuit The positive output end of the circuit is connected to the positive power supply end of the face recognition module;

When the voltage of the power supply battery is greater than the power supply voltage of the face recognition module, the sixth switch is turned on and the seventh switch is turned off; when the voltage of the power supply battery is lower than the In the case of the power supply voltage of the face recognition module, the sixth switch tube is turned off, and the seventh switch tube is turned on.

Among them, the embodiment of the present application designs a buck-boost module in which the buck circuit and the boost circuit are connected in parallel, and the switching of the buck-boost module between the buck mode and the boost mode can be realized through the switching of the two circuits. Reduce the complexity of circuit design.

The second aspect of the embodiments of the present application provides a power supply system, including the power supply circuit and the face recognition module described in the first aspect above.

The third aspect of the embodiment of the present application provides a smart door lock, including the power supply circuit described in the first aspect above, a face recognition module and a door lock switch, and the face image collected by the face recognition module When the face verification is passed, the door lock switch is turned on.

The embodiment of this application designs a power supply circuit including a power supply battery, an anti-reverse connection module and a buck-boost module, which can not only supply power to the face recognition module when the voltage of the power supply battery is greater than the power supply voltage of the face recognition module , and can also supply power for the face recognition module when the voltage of the power supply battery is lower than the power supply voltage of the face recognition module, and can make full use of the power of the power supply battery to prolong the battery life of the face recognition module.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on these drawings without creative work.

Fig. 1 is a structural schematic diagram of an existing power supply circuit;

FIG. 2 is a schematic structural diagram of a power supply circuit provided by an embodiment of the present application;

FIG. 3 is a schematic structural diagram of another power supply circuit provided by an embodiment of the present application;

FIG. 4 is a schematic structural diagram of another power supply circuit provided by an embodiment of the present application;

Fig. 5 is a schematic structural diagram of a buck-boost module provided by an embodiment of the present application;

Fig. 6 is a schematic structural diagram of another buck-boost module provided by the embodiment of the present application;

FIG. 7 is a schematic structural diagram of a power supply system provided by an embodiment of the present application;

Fig. 8 is a schematic structural diagram of a smart door lock provided by an embodiment of the present application.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the application with reference to the drawings in the embodiments of the application. Apparently, the described embodiments are only some of the embodiments of the application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of this application.

The terms "first", "second" and the like in the specification and claims of the present application and the above drawings are used to distinguish different objects, rather than to describe a specific order. Furthermore, the terms "include" and "have", as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally includes Other steps or units inherent in a process, product, or equipment.

Reference in this application to an "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The occurrences of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is understood explicitly and implicitly by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

At present, face recognition technology has gradually become popular in smart door locks, and more and more door lock manufacturers have begun to introduce three-dimensional (3dimension, 3D) face recognition smart door locks, through face recognition technology to achieve non-contact The door opening experience improves the safety and convenience of the door lock. Compared with the fingerprint recognition door lock, the face recognition module has higher requirements on the hardware, followed by greater power consumption. Most of the current face recognition smart door locks use lithium batteries or dry batteries The scheme of power supply for the step-down circuit.

At present, most of the 3D face recognition modules only support 5V narrow voltage input, and a step-down DC-DC (direct current-direct current, DC-DC) power chip needs to be added for power supply using dry batteries in series. The battery life of the step-down DC-DC power supply chip is short, and the dry battery is connected in series. When the battery power is lower than 5.5V, the step-down DC-DC power supply chip cannot work. As shown in FIG. 1 , FIG. 1 is a schematic structural diagram of an existing power supply circuit, as shown in FIG. 1 . The battery is connected to the input end of the DC-DC power chip through the anti-reverse diode Df, and the output end of the DC-DC power chip is connected to the face recognition module.

The embodiment of the present application provides a power supply circuit, a power supply system and an intelligent door lock, which can make full use of the power of the power supply battery and prolong the battery life of the face recognition module.

Please refer to FIG. 2 . FIG. 2 is a schematic structural diagram of a power supply circuit provided by an embodiment of the present application. As shown in Figure 2, the power supply circuit 100 includes a power supply battery 10, an anti-reverse connection module 20 and a buck-boost module 30, the power supply circuit 100 is used to supply power to the face recognition module 200, and the anti-reverse connection module 20 is used for Cut off the output of the power supply battery 100 when the positive and negative poles of the power supply battery 10 are reversely connected;

The positive pole of the power supply battery 10 is connected to the first end of the anti-reverse connection module 20, and the second end of the anti-reverse connection module 20 is connected to the input positive pole of the buck-boost module 30, and the buck-boost module 30 The output positive pole of the face recognition module 200 is connected to the positive power supply end of the face recognition module 200, the negative pole of the power supply battery 10, the input negative pole of the buck-boost module 30, the output negative pole of the buck-boost module 30 and the human body The negative power supply end of the face recognition module 200 is grounded;

When the voltage of the power supply battery 10 is greater than the power supply voltage of the face recognition module 200, the buck-boost module 30 works in a step-down mode; In the case of identifying the power supply voltage of the module 200, the buck-boost module 30 works in a boost mode.

In the embodiment of the present application, the power supply battery 10 may be a lithium battery or a dry battery. Specifically, at least two lithium batteries or dry batteries connected in series may be included, so that the voltage of the lithium batteries or dry batteries connected in series can be greater than the power supply voltage supported by the face recognition module 200 .

Generally speaking, the power supply voltage supported by the face recognition module 200 is 5V, and only small fluctuations are allowed. For example, the face recognition module 200 can only work normally in the range of 4.9-5.1V. When the input voltage of the face recognition module 200 is not in the above range, the face recognition module 200 may work abnormally. In order to ensure the stable operation of the face recognition module 200, it is necessary to ensure the stability of its input voltage. For example, when the power supply voltage supported by the face recognition module 200 is 5V, more than four 1.5V dry batteries can be used in series as the power supply battery 10 .

The main function of the anti-reverse connection module 20 is to prevent the current of the power supply battery 10 from flowing back into the components of the power supply circuit 100 when the power supply battery 10 is reversely connected, and prevent the entire power supply circuit 100 from being burned. The anti-reverse connection module 20 can use diodes, triodes, MOS tubes and the like.

The buck-boost module 30 is a module that can be switched between a buck mode and a boost mode. The buck-boost module 30 can decide to work in buck mode or boost mode according to the voltage of the power supply battery 10 and the power supply voltage of the face recognition module 200, not only when the voltage of the power supply battery 10 is greater than that of the face recognition module 200 When the power supply voltage is lower than the power supply voltage of the face recognition module 200, it can also supply power for the face recognition module 200 when the voltage of the power supply battery 10 is less than the power supply voltage of the face recognition module 200, so that the power of the power supply battery 10 can be fully utilized. Electric energy prolongs the battery life of the face recognition module 200.

Wherein, the step-down mode refers to a mode of converting an input high voltage into an output low voltage. In the step-down mode, the buck-boost module 30 can convert the input high voltage into an output low voltage, so that the output voltage is lower than the input voltage. The boost mode refers to a mode that converts an input low voltage into an output high voltage. In boost mode, the boost boost module can convert the input low voltage to output high voltage, so that the output voltage is greater than the input voltage.

Specifically, when the voltage of the power supply battery 10 is greater than the power supply voltage of the face recognition module 200, the buck-boost module 30 works in a buck mode, so that the voltage output by the buck-boost module 30 is equal to the power supply voltage of the face recognition module 200. Voltage. When the voltage of the power supply battery 10 is lower than the power supply voltage of the face recognition module 200, the buck-boost module 30 works in a boost mode, so that the voltage output by the buck-boost module 30 is equal to the power supply voltage .

Optionally, as shown in FIG. 3 , the anti-reverse connection module 20 includes a first switch tube Q1, the anode of the parasitic diode D2 of the first switch tube Q1 is connected to the anode of the power supply battery 10, and the parasitic diode D2 The negative pole of D2 is connected to the input positive pole of the buck-boost module 30 .

Due to the large power loss of the anti-battery reverse connection diode, the diode voltage drop of the face recognition module 200 is 0.5-0.7V when the face recognition module 200 is working at full load, and the instantaneous power consumption is relatively large, which increases the heating of the diode.

In the embodiment of the present application, the first switch tube Q1 is used as the anti-reverse connection module 20 , which can prevent the entire circuit from being burned out when the power supply battery 10 is connected in reverse. Since the working voltage drop of the switching tube is much smaller than that of the diode, the power consumption of the switching tube is lower than that of the diode, which can realize the anti-reverse connection function and significantly reduce power consumption and heat generation.

Specifically, the first switching transistor Q1 in FIG. 3 is described by taking a PMOS transistor as an example. The first end of the first switching transistor Q1 is the source (source, S) of the PMOS transistor, and the second end of the first switching transistor Q1 is the drain (drain D) of the PMOS transistor, and the control terminal of the first switching transistor Q1 is the gate (gate, G) of the PMOS transistor. When the power supply battery 10 is positively connected, the parasitic diode of the PMOS tube is turned on, V _GS of the PMOS tube=-V _bat , V _DS is turned on, and the power supply battery 10 supplies power to the face recognition module 200; when the power supply battery 10 is reversely connected When V _GS =V _bat , V _DS is cut off to protect the safety of the power supply circuit 100 .

Optionally, as shown in FIG. 4 , the anti-reverse connection module 20 includes a first diode D1, the anode of the first diode D1 is connected to the anode of the power supply battery 10, and the first diode D1 The negative pole of the tube D1 is connected to the input positive pole of the buck-boost module 30 .

The embodiment of the present application uses the first diode D1 as the anti-reverse connection module 20, which can prevent the entire circuit from burning out when the power supply battery 10 is reversed, and can be used in scenarios that are not sensitive to power consumption. Compared with the use of switching tubes, The price of the diode is lower, which can reduce the cost of the power supply circuit 100 .

Please refer to FIG. 5. FIG. 5 is a schematic structural diagram of a buck-boost module 30 provided by an embodiment of the present application. As shown in FIG. 5, the buck-boost module 30 includes a control module (not shown in FIG. 5), a first The second switching tube Q2, the third switching tube Q3, the fourth switching tube Q4, the fifth switching tube Q5, the first capacitor C1, the second capacitor C2 and the first inductor;

The first end of the first capacitor C1 is connected to the first end of the second switching transistor Q2 and the second end of the first switching transistor Q1, and the second end of the second switching transistor Q2 is connected to the first switching transistor Q2. The first terminal of the fifth switching tube Q5 is connected to the first terminal of the first inductor, and the second terminal of the first inductor is connected to the first terminal of the third switching tube Q3 and the first terminal of the fourth switching tube Q4. One end, the second end of the third switching transistor Q3 is connected to the first end of the second capacitor C2 and the positive power supply end of the face recognition module 200, the second end of the first capacitor C1, The second end of the fourth switching transistor Q4, the second end of the fifth switching transistor Q5, and the second end of the second capacitor C2 are grounded;

The control module includes a first output interface (not shown in FIG. 5 ), a second output interface (not shown in FIG. 5 ), a third output interface (not shown in FIG. 5 ) and a fourth output interface (not shown in FIG. 5 ). 5), the first output interface is connected to the control terminal of the second switching tube Q2, the second output interface is connected to the control terminal of the third switching tube Q3, and the third output interface is connected to The control terminal of the fourth switching tube Q4, the fourth output interface is connected to the control terminal of the fifth switching tube Q5, and the control terminal of the first switching tube Q1 is connected to the negative pole of the power supply battery 10.

In the embodiment of the present application, the control module can send the control terminal of the second switching tube Q2, the control terminal of the third switching tube Q3, the The control terminals of the four switching tubes Q4 and the fifth switching tube Q5 send control signals to control these switching tubes to be in any one of on, off or pulse width modulation (Pulse Width Modulation, PWM) modes.

The buck-boost module 30 of the embodiment of the present application is designed with two capacitors at the input and output to prevent the input voltage and output voltage of the buck-boost module 30 from changing suddenly, thereby ensuring that the face recognition module of the buck-boost module 30 is switched between modes. The power supply voltage of the face recognition module 200 will not change abruptly, thereby ensuring the stable power supply of the face recognition module 200 . The buck-boost module 30 is designed with four switch tubes, and the step-down mode and the boost mode are realized by controlling the working states of the four switch tubes. Due to the fast response speed of the switch tubes, the mode switching can be quickly realized, further ensuring the facial recognition mode Stable power supply for group 200.

Optionally, when the voltage of the power supply battery 10 is greater than the power supply voltage of the face recognition module 200, the control module controls the third switching transistor Q3 to be turned on and the fourth switching transistor Q4 to be turned on. When it is turned off, the second switch tube Q2 and the fifth switch tube Q5 work in the first pulse width modulation PWM mode, so that the buck-boost module 30 works in the buck mode.

As shown in FIG. 5 , the first switching tube Q1 is an example of a PMOS tube, and the second switching tube Q2 , third switching tube Q3 , fourth switching tube Q4 , and fifth switching tube Q5 are all taken as an example of an NMOS tube. The anode of the parasitic diode of the second switching transistor Q2 is connected to the second end of the second switching transistor Q2 and the first end of the first inductor, and the negative electrode of the parasitic diode of the second switching transistor Q2 is connected to the first The first terminal of capacitor C1. The anode of the parasitic diode of the third switching transistor Q3 is connected to the second end of the first inductor, and the negative electrode of the parasitic diode of the third switching transistor Q3 is connected to the first end of the second capacitor C2. The anode of the parasitic diode of the fourth switching transistor Q4 is connected to the anode of the parasitic diode of the fifth switching transistor Q5, the second end of the first capacitor C1 and the second end of the second capacitor C2, the The cathode of the parasitic diode of the fourth switching transistor Q4 is connected to the second end of the first inductor, and the cathode of the parasitic diode of the fifth switching transistor Q5 is connected to the first end of the first inductor.

In the embodiment of the present application, the buck-boost module 30 can control the status of the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, and the fifth switch tube Q5, so as to control the buck-boost module 30 to work in the step-down mode. Voltage mode, due to the fast response speed of the switching tube, the mode switching can be quickly realized to ensure the stable power supply of the face recognition module 200.

In the first PWM mode, the duty ratio of the first PWM signal sent by the control module to the control terminal of the second switching transistor Q2 and the control terminal of the fifth switching transistor Q5 is D1, which can be determined according to The ratio of the output positive pole voltage of the buck-boost module to the input positive pole voltage of the buck-boost module is determined, for example:

D1＝Vout/Vin (1)

In formula (1), the Vout is the output positive voltage of the buck-boost module 30 , and the Vin is the input positive voltage of the buck-boost module 30 .

Those skilled in the art should understand that formula (1) can also be modified according to needs, for example, the duty ratio D1 can also be obtained according to the product of the above ratio and a preset coefficient.

The control module can adjust the duty cycle of the first PWM signal at the control terminal of the second switching tube Q2 and the control terminal of the fifth switching tube Q5 in real time according to the change of the input positive voltage of the buck-boost module 30, so that the lifting The output voltage of the voltage module 30 can be kept stable, thereby ensuring the stable power supply of the face recognition module 200 .

In the step-down mode, the working principle of the buck-boost module 30 will be described below with reference to FIG. 5 . The first switching tube Q1 in Figure 5 is taken as an example of a PMOS tube, the second switching tube Q2, the third switching tube Q3, the fourth switching tube Q4, and the fifth switching tube Q5 are all taken as an example of an NMOS tube. The power supply voltage of the module 200 is 5V as an example. When the voltage of the power supply battery 10 is greater than or equal to 5V, the first switch tube Q1 is turned on, the control module sends the first PWM signal to the control terminal of the second switch tube Q2 through the first output interface, and the control module sends the first PWM signal to the fifth switch tube Q2 through the fourth output interface. The control terminal of the switch tube Q5 sends a first PWM signal, the control module sends a high-level signal to the control terminal of the third switch tube Q3 through the second output interface, and the control module sends a high-level signal to the control terminal of the fourth switch tube Q4 through the third output interface. Send low level signal. The control module controls the third switch tube Q3 to be turned on, the fourth switch tube Q4 to be turned off, and the second switch tube Q2 and the fifth switch tube Q5 to work in the first PWM mode. At this time, the second switching tube Q2, the third switching tube Q3, the fifth switching tube Q5, the first inductor and the second capacitor C2 constitute a step-down (buck) circuit, so that the buck-boost module 30 works in a buck circuit. model. In the first PWM mode, the duty ratio of the first PWM signal sent by the control module to the control terminal of the second switch tube Q2 and the control terminal of the fifth switch tube Q5 is D1, for example, refer to the above formula (1).

In the embodiment of the present application, a voltage higher than 1V may be regarded as a high-level signal, and a voltage lower than 0.3V may be regarded as a low-level signal. For example, you can define a high-level signal as 3.3V or 5V, and a low-level signal as 0V. The switching frequency of the first PWM signal can be set to tens of KHz or hundreds of KHz.

Optionally, when the voltage of the power supply battery 10 is lower than the power supply voltage of the face recognition module 200, the control module controls the second switching transistor Q2 to turn on, and the fifth switching transistor Q5 When it is turned off, the third switch tube Q3 and the fourth switch tube Q4 work in the second PWM mode, so that the buck-boost module 30 works in the boost mode.

In the embodiment of the present application, the buck-boost module 30 can control the states of the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, and the fifth switch tube Q5, so as to control the buck-boost module 30 to work in the step-up mode. Voltage mode, due to the fast response speed of the switching tube, the mode switching can be quickly realized to ensure the stable power supply of the face recognition module 200.

In the second PWM mode, the duty cycle D2 of the second PWM signal sent by the control module to the control terminal of the third switching transistor Q3 and the control terminal of the fourth switching transistor Q4 can be based on 1 Determining by subtracting the ratio of the input positive pole voltage of the buck-boost module to the positive voltage output of the buck-boost module, for example:

D2＝1-Vin/Vout (2)

In formula (2), the Vout is the output positive voltage of the buck-boost module 30 , and the Vin is the input positive voltage of the buck-boost module 30 .

Those skilled in the art should understand that the formula (2) can also be modified according to needs, for example, the duty ratio D2 can also be obtained according to the product of the above difference and the preset coefficient, or the ratio Vin/Vout can be multiplied by the preset coefficient, It is then obtained by subtracting the result of the multiplication from 1.

The control module can adjust the duty cycle of the second PWM signal at the control terminal of the third switching tube Q3 and the control terminal of the fourth switching tube Q4 in real time according to the change of the input positive electrode voltage of the buck-boost module 30, so that the lifting The output voltage of the voltage module 30 can be kept stable, thereby ensuring the stable power supply of the face recognition module 200 .

In the boost mode, the working principle of the buck-boost module 30 will be described below with reference to FIG. 5 . The first switching tube Q1 in Figure 5 is taken as an example of a PMOS tube, the second switching tube Q2, the third switching tube Q3, the fourth switching tube Q4, and the fifth switching tube Q5 are all taken as an example of an NMOS tube. The power supply voltage of the module 200 is 5V as an example. When the voltage of the power supply battery 10 is in the range of 3-5V, the first switch tube Q1 is turned on, the control module sends a high-level signal to the control terminal of the second switch tube Q2 through the first output interface, and the control module transmits a high-level signal through the fourth output interface Send a low-level signal to the control terminal of the fifth switching tube Q5, the control module sends a second PWM signal to the control terminal of the third switching tube Q3 through the second output interface, and the control module sends a second PWM signal to the fourth switching tube Q4 through the third output interface The control terminal sends the second PWM signal. The control module controls the second switch tube Q2 to be turned on, the fifth switch tube Q5 to be turned off, and the third switch tube Q3 and the fourth switch tube Q4 to work in the second PWM mode. At this time, the second switching tube Q2, the third switching tube Q3, the fourth switching tube Q4, the first inductor and the second capacitor C2 form a boost circuit, so that the buck-boost module 30 works in a boost circuit. model. In the second PWM mode, the duty ratio of the second PWM signal sent by the control module to the control terminal of the third switching tube Q3 and the control terminal of the fourth switching tube Q4 is D2, for example, refer to the above formula (2).

Optionally, please refer to FIG. 6 . FIG. 6 is a schematic structural diagram of another buck-boost module provided in an embodiment of the present application. As shown in FIG. 6, the buck-boost module 30 includes a buck circuit 31, a boost circuit 32, a sixth switching tube Q6 and a seventh switching tube Q7;

The second end of the anti-reverse connection module 20 is the first end of the sixth switching transistor Q6 and the first end of the seventh switching transistor Q7, and the second end of the sixth switching transistor Q6 is connected to the step-down The positive input end of the pressure circuit 31, the positive output end of the step-down circuit 31 is connected to the positive power supply end of the face recognition module 200; the second end of the seventh switching tube Q7 is connected to the boost circuit 32 The positive input end of the booster circuit 32 is connected to the positive power supply end of the face recognition module 200;

When the voltage of the power supply battery 10 is greater than the power supply voltage of the face recognition module 200, the sixth switch tube Q6 is turned on, and the seventh switch tube Q7 is turned off; When the voltage is lower than the power supply voltage of the face recognition module 200, the sixth switching transistor Q6 is turned off, and the seventh switching transistor Q7 is turned on.

Wherein, the control terminal of the sixth switch tube Q6 and the control terminal of the seventh switch tube Q7 can be connected to a control module (not shown in FIG. 6 ), and the conduction of the sixth switch tube Q6 and the seventh switch tube Q7 is controlled by the control module. or off.

When the voltage of the power supply battery 10 is greater than the power supply voltage of the face recognition module 200, the sixth switching tube Q6 is turned on, and the seventh switching tube Q7 is turned off. At this time, the step-down circuit 31 works, and the boost circuit 32 does not work. , the buck-boost module 30 works in a buck mode. When the voltage of the power supply battery 10 is lower than the power supply voltage of the face recognition module 200, the sixth switching tube Q6 is turned off, and the seventh switching tube Q7 is turned on. At this time, the step-down circuit 31 does not work, and the boost circuit 32 works. , the buck-boost module 30 works in a boost mode.

Both the sixth switching transistor Q6 and the seventh switching transistor Q7 in FIG. 6 are NMOS transistors as an example.

In the embodiment of the present application, by designing a buck-boost module 30 in which a buck circuit 31 and a boost circuit 32 are connected in parallel, the buck-boost module 30 can be switched between the buck mode and the boost mode by switching the two circuits. , can reduce the complexity of the circuit design.

Please refer to FIG. 7. FIG. 7 is a schematic structural diagram of a power supply system provided by an embodiment of the present application. As shown in FIG. 7, the power supply system 300 includes the power supply circuit 100 and the face recognition module 200 shown in FIG. The power supply circuit 100 supplies power to the face recognition module 200 . The face recognition module may be a 3D face recognition module. The power supply system of the embodiment of the present application can make full use of the electric energy of the power supply battery to prolong the battery life of the face recognition module.

Please refer to FIG. 8. FIG. 8 is a schematic structural diagram of a smart door lock provided by an embodiment of the present application. As shown in FIG. 8, the smart door lock 500 includes the power supply circuit 100 and the face recognition module 200 shown in FIG. And the door lock switch 400, when the face image collected by the face recognition module 200 passes the face verification, the door lock switch 400 is turned on. The smart door lock of the embodiment of the present application can make full use of the power of the power supply battery to prolong the battery life of the face recognition module.

In the foregoing embodiments, the descriptions of each embodiment have their own emphases, and for parts not described in detail in a certain embodiment, reference may be made to relevant descriptions of other embodiments.

In the several embodiments provided in this application, it should be understood that the disclosed device can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or can be Integrate into another system, or some features may be ignored, or not implemented.

Claims

A power supply circuit, including a power supply battery, an anti-reverse connection module and a buck-boost module, the power supply circuit is used to supply power to a face recognition module, and the anti-reverse connection module is used to reversely connect the positive and negative poles of the power supply battery cut off the output of the power supply battery;

The positive pole of the power supply battery is connected to the first end of the anti-reverse connection module, the second end of the anti-reverse connection module is connected to the input positive pole of the buck-boost module, and the output positive pole of the buck-boost module is connected to the The positive power supply terminal of the face recognition module, the negative pole of the power supply battery, the input negative pole of the buck-boost module, the negative output pole of the buck-boost module, and the negative power supply terminal of the face recognition module are grounded ;

When the voltage of the power supply battery is greater than the power supply voltage of the face recognition module, the buck-boost module works in buck mode; when the voltage of the power supply battery is lower than the face recognition module In the case of supply voltage, the buck-boost module works in boost mode.
The power supply circuit according to claim 1, wherein the anti-reverse connection module includes a first switch tube, the anode of the parasitic diode of the first switch tube is connected to the anode of the power supply battery, and the cathode of the parasitic diode is connected to The input positive pole of the buck-boost module.
The power supply circuit according to claim 1, wherein the anti-reverse connection module includes a first diode, the anode of the first diode is connected to the anode of the power supply battery, and the anode of the first diode is The negative pole is connected to the input positive pole of the buck-boost module.
The power supply circuit according to claim 2, wherein the buck-boost module comprises a control module, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a first capacitor, a second capacitor and first inductance;

The first end of the first capacitor is connected to the first end of the second switch tube and the second end of the first switch tube, and the second end of the second switch tube is connected to the fifth switch tube. The first end and the first end of the first inductance, the second end of the first inductance is connected to the first end of the third switching tube and the first end of the fourth switching tube, the third The second end of the switch tube is connected to the first end of the second capacitor and the positive power supply end of the face recognition module, the second end of the first capacitor, the second end of the fourth switch tube, The second terminal of the fifth switch tube and the second terminal of the second capacitor are grounded;

The control module includes a first output interface, a second output interface, a third output interface and a fourth output interface, the first output interface is connected to the control terminal of the second switching tube, and the second output interface is connected to the The control terminal of the third switching tube, the third output interface is connected to the control terminal of the fourth switching tube, the fourth output interface is connected to the control terminal of the fifth switching tube, and the control terminal of the first switching tube The control end is connected to the negative pole of the power supply battery.
The power supply circuit according to claim 4, wherein, when the voltage of the power supply battery is greater than the power supply voltage of the face recognition module, the control module controls the third switch to be turned on, the The fourth switch tube is turned off, and the second switch tube and the fifth switch tube work in the first pulse width modulation PWM mode.
The power supply circuit according to claim 5, wherein, in the first PWM mode, the first PWM signal sent by the control module to the control terminal of the second switch tube and the control terminal of the fifth switch tube The duty cycle of the signal;

Wherein, the duty cycle of the first PWM signal is determined according to the ratio of the output anode voltage of the buck-boost module to the input anode voltage of the buck-boost module.
The power supply circuit according to any one of claims 4-6, wherein, when the voltage of the power supply battery is lower than the power supply voltage of the face recognition module, the control module controls the second switch tube is turned on, the fifth switch tube is turned off, and the third switch tube and the fourth switch tube work in the second PWM mode.
The power supply circuit according to claim 7, wherein, in the second PWM mode, the second PWM signal sent by the control module to the control terminal of the third switch tube and the control terminal of the fourth switch tube The duty cycle of the signal;

Wherein, the duty ratio of the second PWM signal is determined according to 1 minus the difference between the input positive voltage of the buck-boost module and the positive voltage output of the buck-boost module.
The power supply circuit according to any one of claims 1 to 3, wherein the buck-boost module includes a buck circuit, a boost circuit, a sixth switch tube, and a seventh switch tube;

The second end of the anti-reverse connection module is the first end of the sixth switch tube and the first end of the seventh switch tube, and the second end of the sixth switch tube is connected to the positive side of the step-down circuit. Input terminal, the positive output terminal of the step-down circuit is connected to the positive power supply terminal of the face recognition module; the second terminal of the seventh switching tube is connected to the positive input terminal of the boost circuit, and the boost circuit The positive output end of the circuit is connected to the positive power supply end of the face recognition module;

When the voltage of the power supply battery is greater than the power supply voltage of the face recognition module, the sixth switch is turned on and the seventh switch is turned off; when the voltage of the power supply battery is lower than the In the case of the power supply voltage of the face recognition module, the sixth switch tube is turned off, and the seventh switch tube is turned on.
A power supply system, comprising the power supply circuit and a face recognition module according to any one of claims 1-9.
An intelligent door lock, including the power supply circuit, face recognition module and door lock switch according to any one of claims 1 to 9, the face image collected by the face recognition module is passed through the face In the case of verification, turn on the door lock switch.