WO2021206520A1

WO2021206520A1 - Energy harvesting-based smart sensor and operating method therefor

Info

Publication number: WO2021206520A1
Application number: PCT/KR2021/004541
Authority: WO
Inventors: 박영주; 김종현; 이경호; 김기현; 서길수; 심민섭
Original assignee: 한국전기연구원
Priority date: 2020-04-10
Filing date: 2021-04-12
Publication date: 2021-10-14
Also published as: KR20210126369A

Abstract

The present invention relates to a method for operating a load device connected to an output terminal of an energy harvesting device, comprising the steps of: detecting the output voltage of the energy harvesting device; comparing the detected output voltage with a predetermined first threshold voltage; maintaining a sleep mode for a predetermined period of time if the detected output voltage is less than the first threshold voltage, and then initiating system booting.

Description

Energy harvesting-based smart sensor and its operation method

The present invention relates to an energy harvesting-based smart sensor, and more particularly, to a smart sensor driven based on power obtained from an energy harvester.

Energy Harvesting refers to a technology that collects and uses natural energy such as environmental energy and solar/wind/algae around devices. It mainly produces power in units of microwatts (㎼) to milliwatts (mW).

Energy harvesting is divided into various categories depending on the method used to obtain energy. For example, the methods that can obtain energy from nature include the solar cell method that obtains energy from sunlight, the thermoelectric method that obtains electrical energy from heat, the piezoelectric method that obtains electrical energy from vibration, and the RF method that obtains energy from electromagnetic waves. There is this.

1 is a diagram showing the configuration of a general energy harvesting device. As shown in FIG. 1 , a general energy harvesting device 10 includes an energy harvester 11 that collects surrounding natural or environmental energy and converts it into electrical energy, and rectifies the output voltage of the energy harvester 11 . a rectifier 12 , an energy storage device 13 for storing electrical energy produced by the energy harvester 11 , and an energy harvesting circuit 14 for charging a voltage to the energy storage device 13 . .

By connecting a predetermined load 20 to the output terminal of the energy harvesting device 10 , power generated by the energy harvester 11 may be supplied to the corresponding load 20 . A typical load device connected to the energy harvesting device 10 may be a smart sensor.

A smart sensor is a kind of intelligent sensor that combines logic/judgment/communication functions with existing sensors to provide high-function, high-precision, high-convenience, and high value-added sensors that perform data processing, automatic correction, self-diagnosis, and decision-making functions. it means. The smart sensor is a cutting-edge device that will open the future intelligent industry and hyper-connection era, and can be applied to various application industries such as manufacturing, environment, mobile, medical healthcare, automobile, space, aviation, and military.

A typical smart sensor includes a sensor unit, a signal processing unit, a communication unit, and a control unit. These smart sensors operate in the order of 'sleep mode' → 'active mode (sensing mode)' → 'data transmission mode' → 'sleep mode' after booting the system when external power is applied.

However, in the case of using the energy harvesting device 10 as the power supply device of the smart sensor, when the current consumed by the sensor during the initial system boot is greater than the current produced by the energy harvester 11, the corresponding harvester 11 ) generated from the current cannot charge the energy storage device 13, and the smart sensor cannot operate properly. That is, when the system of the smart sensor is booted immediately in a state where the power stored in the energy storage device 13 of the energy harvesting device 10 is small, the power consumption in the corresponding sensor is large, so the energy harvested by the energy harvester 11 is The current cannot charge the energy storage device 13 and the smart sensor cannot properly operate. Therefore, there is a need for a method for stably driving smart sensors that consume a lot of load current during initial system booting.

SUMMARY OF THE INVENTION The present invention aims to solve the above and other problems. Another object of the present invention is to provide a smart sensor that detects an output voltage of an energy harvesting device and enters a booting mode based on the sensed output voltage, and an operating method thereof.

According to an aspect of the present invention to achieve the above or other object, there is provided an operating method of a load device connected to an output terminal of an energy harvesting device, the method comprising: detecting an output voltage of the energy harvesting device; comparing the detected output voltage with a first predetermined threshold voltage; When the detected output voltage is less than the first threshold voltage, the method of operating a load device includes maintaining a sleep mode for a predetermined time and then starting system booting. Here, the load device may include a smart sensor. In addition, the first threshold voltage may be a minimum voltage level required to boot the system in the smart sensor.

More preferably, the method of operating the load device may further include immediately starting system booting without the need to maintain a sleep mode when the output voltage of the energy harvesting device is equal to or greater than a predetermined first threshold voltage. have.

More preferably, the method of operating the load device may further include initializing only a minimum device for maintaining the operation mode of the smart sensor in a sleep mode, among a plurality of devices constituting the smart sensor. have.

More preferably, the method of operating the load device may further include entering a device initialization mode for initializing a plurality of devices constituting the smart sensor when the system is booted.

More preferably, the method of operating the load device includes the steps of: checking whether there is a device consuming more than a certain amount of power in the initialization mode among a plurality of devices constituting the smart sensor when entering the device initialization mode; detecting an output voltage of the energy harvesting device when there is a device consuming more than a certain amount of power in the initialization mode, and comparing the sensed output voltage with a second predetermined threshold voltage; and when the sensed output voltage is less than the second threshold voltage, maintaining the sleep mode for a predetermined time and then initializing the device. Here, the second threshold voltage is characterized in that it is a minimum voltage level required to initialize a device consuming more than a certain amount of power.

More preferably, when the output voltage of the energy harvesting device is equal to or greater than a second threshold voltage, the method of operating the load device comprises immediately initializing a device consuming more than a certain amount of power.

According to another aspect of the present invention, there is provided a load device connected to an output terminal of an energy harvesting device, the load device comprising: a sensor unit for sensing surrounding environment information; a signal processing unit converting the analog signal output from the sensor unit into a digital signal; and a control unit that detects an output voltage of the energy harvesting device and, when the detected output voltage is less than a predetermined first threshold voltage, maintains a sleep mode for a predetermined time and then starts system booting load device is provided.

According to another aspect of the present invention, the process of detecting the output voltage of the energy harvesting device; comparing the detected output voltage with a first predetermined threshold voltage; When the detected output voltage is less than the first threshold voltage, a computer program stored in a computer-readable recording medium is provided so that a process of starting system booting is performed on a computer after maintaining a sleep mode for a predetermined time. .

The effects of the energy harvesting-based smart sensor and its operating method according to embodiments of the present invention will be described as follows.

According to at least one of the embodiments of the present invention, the output voltage of the energy harvesting device is increased by monitoring the output voltage of the energy harvesting device and actively utilizing the sleep mode function from the system initialization stage requiring relatively large power. It has the advantage of being able to perform a stable system boot even when it is very low.

In addition, according to at least one of the embodiments of the present invention, by monitoring the output voltage of the energy harvesting device and entering the system booting mode only when the voltage is greater than or equal to a predetermined threshold voltage, the energy harvesting device in the existing smart sensor It has the advantage of effectively solving the problem of not being able to boot the system due to insufficient output voltage.

However, the effects that can be achieved by the energy harvesting-based smart sensor and the operating method thereof according to the embodiments of the present invention are not limited to those mentioned above, and other effects not mentioned above are described in the present invention from the description below. It will be clearly understood by those of ordinary skill in the art.

1 is a view showing the configuration of a general energy harvesting device;

2 is a diagram showing the configuration of an energy harvesting system according to an embodiment of the present invention;

3 is a diagram showing the configuration of an energy harvesting-based smart sensor according to an embodiment of the present invention;

4 is a flowchart illustrating an operation of an energy harvesting-based smart sensor according to an embodiment of the present invention;

FIG. 5 is a flowchart illustrating a method of initializing devices with high power consumption among a plurality of devices constituting a smart sensor in the system booting step of FIG. 4 .

Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but the same or similar components are assigned the same reference numerals regardless of reference numerals, and overlapping descriptions thereof will be omitted. The suffixes "module" and "part" for the components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have a meaning or role distinct from each other by themselves.

In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in the present specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed herein is not limited by the accompanying drawings, and all changes included in the spirit and scope of the present invention , should be understood to include equivalents or substitutes.

The present invention provides a load device that detects an output voltage of an energy harvesting device and enters a booting mode based on the sensed output voltage, and a method of operating the same. Hereinafter, in the present specification, for convenience of description, a 'smart sensor' is exemplified as a load device, but is not limited thereto, and includes all electronic devices that can be driven based on power obtained from an energy harvester.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the drawings.

2 is a diagram showing the configuration of an energy harvesting system according to an embodiment of the present invention.

Referring to FIG. 2 , the energy harvesting system 100 according to an embodiment of the present invention includes an energy harvesting device 110 and a smart sensor 120 linked to the energy harvesting device 110 . . Here, the energy harvesting device 110 includes an energy harvester 111 , a rectifier 112 , an energy harvesting circuit 113 , and an energy storage device 114 .

The energy harvester 111 is a device for harvesting energy using resources that are not used or discarded in nature or the environment around the device, and mainly produces electrical energy in units of microwatts (㎼) to milliwatts (mW). As the energy harvester 111, any one of a piezoelectric harvester, an electrostatic harvester, an electromagnetic harvester, a thermoelectric harvester, a biomechanical harvester, a solar cell harvester, a triboelectric harvester, and an RF harvester may be used, but is not necessarily limited thereto.

The rectifier 112 may be connected to an output terminal of the energy harvester 111 to convert alternating current (AC) power output from the energy harvester 111 into direct current (DC) power. For example, the rectifier 112 may include full bridge type diodes D ₁ to D ₄ and one output capacitor C ₁ .

The energy harvesting circuit 113 is disposed between the output terminal of the rectifier 112 and the input terminal of the energy storage device 114 , and uses the _{output voltage V IN of the rectifier 112 to store the energy storage device 114 .} ) can be charged.

The energy harvesting circuit 113 is a constant current (CC) mode or a constant voltage (CV) mode according to the state of charge (SOC) of the energy storage device 114 in the corresponding energy storage device. (114) can be charged. For example, the energy harvesting circuit 113 charges in the constant current (CC) mode until the energy storage device 114 is fully charged, and enters the constant voltage (CV) mode when the energy storage device 114 is fully charged. recharge

The energy storage device 114 may be disposed between the energy harvesting circuit 113 and the load, that is, the smart sensor 120 to store electrical energy produced by the energy harvester 111 . As the energy storage device 114 , a battery, a super capacitor, a storage battery, or the like may be used, but is not limited thereto.

The energy storage device 114 may store electrical energy provided from the energy harvesting circuit 113 in the charging mode. In addition, the energy storage device 114 may supply pre-stored electrical energy to the smart sensor 120 in the discharge mode.

The smart sensor 120, as a kind of intelligent sensor, combines logic/judgment/communication functions with a general sensor to perform data processing, automatic correction, self-diagnosis, decision-making functions, etc. value-added sensor. The smart sensor 120 is a combination of micro sensor technology and semiconductor VLSI (Very Large Scale Integration) technology, and may have excellent data processing capability, judgment function, memory function, communication function, and the like of a computer.

The smart sensor 120 may be connected to an output terminal of the energy harvesting device 110 to receive load power from the energy harvesting device 110 . _{The smart sensor 120 may detect an output voltage V OUT} of the energy harvesting device 110 when load power is applied, and enter a booting mode based on the sensed output voltage. This is to boot the system of the smart sensor 120 only when the power stored in the energy storage device 114 of the energy harvesting device 110 is sufficient.

The smart sensor 120 may repeatedly perform a predetermined basic operation upon completion of system booting. For example, the smart sensor 120 may perform repetitive operations while changing its operation mode in the order of 'sleep mode', 'active mode (or sensing mode)', 'data transmission mode' and 'sleep mode'. .

3 is a diagram showing the configuration of an energy harvesting-based smart sensor according to an embodiment of the present invention.

Referring to FIG. 3 , a smart sensor 120 based on energy harvesting according to an embodiment of the present invention includes a sensor unit 121 , a signal processing unit 122 , a wireless communication unit 123 , a memory (not shown), and a control unit. (124). The components shown in FIG. 3 are not essential for implementing the smart sensor, so the smart sensor described herein may have more or fewer components than those listed above.

The sensor unit 121 may perform a function of detecting information by quantitatively measuring a phenomenon in the physical or environmental system instead of the human five senses. For example, the sensor unit 121 may sense surrounding environment information such as temperature, humidity, illuminance, atmospheric pressure, acceleration, gas, sound, and image. According to the sensing target of the sensor unit 121 , the smart sensor 120 may be classified into a physical sensor, an optical sensor, a chemical sensor, and a biosensor.

The signal processing unit 122 may include at least one of an A/D converter that converts an analog signal into a digital signal and a D/A converter that converts a digital signal into an analog signal. Here, the A/D converter may convert the analog signal output from the sensor unit 121 into a digital signal and provide the converted digital signal to the control unit 124 . Conversely, the D/A converter may convert the digital signal output from the control unit 124 into an analog signal and provide the converted analog signal to the sensor unit 121 .

The wireless communication unit 123 is for short range communication, and includes Bluetooth™, Radio Frequency Identification (RFID), Infrared Data Association (IrDA), Ultra-Wideband (UWB), ZigBee, NFC. At least one of (Near Field Communication), Wireless-Fidelity (Wi-Fi), Wi-Fi Direct, and Wireless Universal Serial Bus (USB) technologies may be used to support short-range communication. Further, the wireless communication unit 123 is a technical standard or communication method for mobile communication (eg, GSM (Global System for Mobile communication), CDMA (Code Division Multi Access), CDMA2000 (Code Division Multi Access 2000), Enhanced Voice-Data Optimized or Enhanced Voice-Data Only (EV-DO), Wideband CDMA (WCDMA), High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), Long Term Evolution (LTE), LTE- Long Term Evolution-Advanced (A) technology, etc.) may be used to support long-distance communication. The wireless communication unit 123 may support wireless communication between a sensor node and a gateway and between a sensor node and an adjacent sensor node through a short-distance and/or long-distance wireless communication network.

The memory stores data supporting various functions of the smart sensor 120 . In addition, the memory may store an application program driven by the smart sensor 120 , data and commands for the operation of the smart sensor 120 .

The controller (or microcontroller unit (MCU)) 124 may control at least some of the components described above in order to drive an application program stored in a memory. Furthermore, the controller 124 may control by combining at least one of the above-described components in order to implement the embodiments described below on the smart sensor 120 according to the present invention.

The controller 124 may control the overall operation of the smart sensor 120 . For example, the controller 124 may control a function related to power management of the smart sensor 120 , a function related to wireless communication, and a function related to analog (A)/digital (D) signal processing.

The control unit 124 may perform a function of distributing the power provided from the energy harvesting device 110 to the components of the smart sensor 120 . When power is applied from the energy harvesting device 110 , the control unit 124 _{detects the output voltage V OUT} of the energy harvesting device 110 , and directly enters the booting mode based on the detected output voltage. It can enter the boot mode or enter the boot mode after going through sleep mode for a certain period of time. A more detailed description thereof will be described later with reference to FIG. 4 below.

The controller 124 may repeatedly perform a predetermined basic operation upon completion of system booting. For example, the controller 124 performs repetitive operations while changing the operation mode of the smart sensor 120 in the order of 'sleep mode', 'active mode (or sensing mode)', 'data transmission mode' and 'sleep mode'. can do.

As described above, the smart sensor according to the present invention actively utilizes the sleep mode function from the system initialization stage, which requires relatively large power, to perform stable system booting even when the output voltage of the energy harvesting device is very low. can do.

4 is a flowchart illustrating an operation of an energy harvesting-based smart sensor according to an embodiment of the present invention.

Referring to FIG. 4 , the controller 124 of the energy harvesting-based smart sensor 120 according to the present invention may check whether power is applied from the energy harvesting device 110 ( S410 ).

As a result of checking in step 410 , when power is applied from the energy harvesting device 110 , the controller 124 may detect an output voltage of the energy harvesting device 110 ( S420 ). That is, the controller 124 may detect the state of charge of the energy storage device 114 included in the energy harvesting device 110 .

The controller 124 may determine whether the output voltage of the energy harvesting device 110 is greater than or equal to a predetermined first threshold voltage (S430). Here, the predetermined first threshold voltage may be a minimum voltage level required to boot the system in the smart sensor 120 .

As a result of checking in step 430 , when the output voltage of the energy harvesting apparatus 110 is less than a predetermined first threshold voltage, the controller 124 may perform an operation for preparing the system for booting ( S440 ). That is, the controller 124 may perform an operation of initializing only the minimum device (or parts) for entering the operation mode of the smart sensor 120 into the sleep mode.

The controller 124 may enter the operation mode of the smart sensor 120 into the sleep mode when the system booting preparation is completed (S450). This is to sufficiently store the power generated by the energy harvester 111 in the energy storage device 114 during the sleep mode of the smart sensor 120 .

The controller 124 may check whether a predetermined time has elapsed from the time when the smart sensor 120 enters the sleep mode by driving a predetermined timer (S460). As a result of the check, when a predetermined time has elapsed from the time of entering the sleep mode, the controller 124 may move to step 420 to detect the output voltage of the energy harvesting apparatus 110 .

Thereafter, the control unit 124 may determine whether the output voltage of the energy harvesting apparatus 110 is greater than or equal to a predetermined first threshold voltage. As a result of the check, when the output voltage of the energy harvesting device 110 is less than the first predetermined threshold voltage, the controller 124 may repeat the above-described operations 440 to 460 .

Meanwhile, as a result of the check, if the output voltage of the energy harvesting device 110 is greater than or equal to the first predetermined threshold voltage, the controller 124 may boot the system of the smart sensor 120 ( S470 ). In this case, the controller 124 may initialize all devices constituting the smart sensor 120 .

The controller 124 may perform a predetermined basic operation upon completion of system booting (S480). For example, the controller 124 performs repetitive operations while changing the operation mode of the smart sensor 120 in the order of 'sleep mode', 'active mode (or sensing mode)', 'data transmission mode' and 'sleep mode'. can do.

On the other hand, in the case of initializing devices with high power consumption among a plurality of devices constituting the smart sensor 120 in the above-described system booting step, the initialization step of the smart sensor 120 may be performed for each device with high power consumption if necessary. It can be configured to divide into several stages, monitor the output voltage of the energy harvesting device at each stage, and then enter the sleep mode or initialization mode. A more detailed description thereof will be described later with reference to FIG. 5 below.

As described above, the smart sensor according to the present invention monitors the output voltage of the energy harvesting device and enters the system booting mode only when the corresponding voltage is greater than or equal to a predetermined threshold voltage. It can effectively solve the problem that the system could not boot due to insufficient output voltage.

Referring to FIG. 5 , the controller 124 may enter a device initialization mode for initializing a plurality of devices constituting the smart sensor 120 when the system is booted ( S510 ).

When entering the device initialization mode, the control unit 124 may check whether a device with high power consumption exists among a plurality of devices constituting the smart sensor 120 ( S520 ). That is, the controller 124 may detect a device consuming more than a predetermined power during initialization. Here, the device with high power consumption may be the sensor unit 121 or the wireless communication unit 123 of the smart sensor 120 , but is not limited thereto.

As a result of the check in step 520 , when a device with high power consumption exists in the smart sensor 120 , the controller 124 may detect an output voltage of the energy harvesting device 110 ( S530 ).

The controller 124 may determine whether the output voltage of the energy harvesting apparatus 110 is greater than or equal to a second threshold voltage predetermined in operation S540. Here, the predetermined second threshold voltage may be a minimum voltage level required to initialize a device with high power consumption.

As a result of checking in step 540, when the output voltage of the energy harvesting device 110 is less than the second predetermined threshold voltage, the controller 124 may switch the operation mode of the smart sensor 120 to the sleep mode ( S550). This is to sufficiently store the power generated by the energy harvester 111 in the energy storage device 114 during the sleep mode of the smart sensor 120 .

The control unit 124 may check whether a predetermined time elapses from the time when the smart sensor 120 enters the sleep mode by driving a predetermined timer (S560). As a result of the check, when a predetermined time has elapsed from the time of entering the sleep mode, the controller 124 may move to step 530 and detect the output voltage of the energy harvesting apparatus 110 .

The control unit 124 may determine whether the output voltage of the energy harvesting device 110 is greater than or equal to a second threshold voltage predetermined. As a result of the check, when the output voltage of the energy harvesting apparatus 110 is less than the second threshold voltage predetermined, the controller 124 may repeat the above-described operations of steps 550 and 560 .

On the other hand, as a result of the check, when the output voltage of the energy harvesting device 110 is greater than or equal to the predetermined second threshold voltage, the controller 124 uses the power obtained from the energy harvesting device 110 to consume power. This large device can be initialized (S570).

Thereafter, the control unit 124 may check whether another device with high power consumption exists among the plurality of devices constituting the smart sensor 120 ( S580 ). As a result of the check, if there is another device with high power consumption, the controller 124 may repeat the above-described operations 530 to 570 . Meanwhile, as a result of the check, if there is no other device having a large power consumption, the controller 124 may move to the basic operation performing step S480 of FIG. 4 described above.

The present invention described above can be implemented as computer-readable code on a medium in which a program is recorded. The computer-readable medium may continuously store a computer-executable program, or may be temporarily stored for execution or download. In addition, the medium may be various recording means or storage means in the form of a single or several hardware combined, it is not limited to a medium directly connected to any computer system, and may exist distributed on a network. Examples of the medium include a hard disk, a magnetic medium such as a floppy disk and a magnetic tape, an optical recording medium such as CD-ROM and DVD, a magneto-optical medium such as a floppy disk, and those configured to store program instructions, including ROM, RAM, flash memory, and the like. Accordingly, the above detailed description should not be construed as restrictive in all respects but as exemplary. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present invention are included in the scope of the present invention.

Claims

In the operating method of a load device connected to the output terminal of the energy harvesting device,

detecting an output voltage of the energy harvesting device;

comparing the detected output voltage with a first predetermined threshold voltage;

and initiating system booting after maintaining the sleep mode for a predetermined time when the detected output voltage is less than the first threshold voltage.
According to claim 1,

The load device operating method, characterized in that it includes a smart sensor (smart sensor).
3. The method of claim 2,

and immediately starting the system booting without the need to maintain the sleep mode when the detected output voltage is greater than or equal to the first threshold voltage.
3. The method of claim 2,

The method of operating a load device further comprising the step of initializing only a minimum device for maintaining the operation mode of the smart sensor in the sleep mode among a plurality of devices constituting the smart sensor.
3. The method of claim 2,

The first threshold voltage, the operating method of the load device, characterized in that the minimum voltage required to boot the system in the smart sensor.
3. The method of claim 2,

The method of operating a load device further comprising the step of entering a device initialization mode for initializing a plurality of devices constituting the smart sensor when the system is booted.
7. The method of claim 6,

checking whether there is a device consuming more than a certain amount of power in the initialization mode among a plurality of devices constituting the smart sensor when entering the device initialization mode;

detecting an output voltage of the energy harvesting device when there is a device consuming more than a certain amount of power in the initialization mode, and comparing the sensed output voltage with a second predetermined threshold voltage; and

and initializing the device after maintaining the sleep mode for a predetermined time when the sensed output voltage is less than the second threshold voltage.
8. The method of claim 7,

The method of operating a load device, characterized in that the second threshold voltage is a minimum voltage level necessary to initialize the device consuming more than a certain amount of power.
8. The method of claim 7,

and directly initializing a device consuming more than the predetermined power when the sensed output voltage is equal to or greater than the second threshold voltage.
A computer program stored in a computer-readable recording medium so that the method according to any one of claims 1 to 9 is performed on a computer.
In the load device connected to the output terminal of the energy harvesting device,

a sensor unit for sensing surrounding environment information;

a signal processing unit converting the analog signal output from the sensor unit into a digital signal; and

a load including a control unit detecting an output voltage of the energy harvesting device and starting system booting after maintaining a sleep mode for a predetermined time when the detected output voltage is less than a predetermined first threshold voltage Device.