Circuit arrangement for extracting energy from energy harvester

Abstract

To reduce energy consumption in integrated circuits used to extract energy from energy harvesters.SOLUTION: A circuit arrangement (1) for extracting energy from an energy harvester (2) includes: an integrated circuit (3) to extract energy from the energy harvester (2); an energy accumulator (4) to receive the energy extracted by the integrated circuit (3); and a switch (5) to selectively disconnect the energy accumulator (4) from the integrated circuit (3). A control signal is for closing the switch (5) when the integrated circuit (3) is able to extract energy from the energy harvester (2), and for opening the switch (5) when the integrated circuit (3) is unable to extract energy from the energy harvester (2) to thereby disconnect the integrated circuit (2) from the energy accumulator (4).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a circuit configuration used in an energy harvesting system for reducing energy consumption in an energy harvesting (environmental power generation) system. The present invention further relates to a method of operating a circuit configuration for extracting energy from an energy harvester and charging (storing electricity) an accumulator of an energy harvesting system.

Background Art

[0002] In today's era where there is a great demand for ubiquitous computing and portable electronic devices, energy harvesting (environmental power generation) has emerged as an important technology for providing a sustainable power source. An energy harvester utilizes ambient energy from the environment such as sunlight, vibration, and temperature gradients and converts it into electric power. Although the future of energy harvesting is certain, the efficiency of power extraction remains a significant concern.

[0003] The advantage of an energy harvester when applied to a portable timepiece (e.g., a wristwatch, a pocket watch) is that it can reduce or eliminate the need for battery replacement of the portable timepiece, making it sustainable for a long time and environmentally friendly. However, the amount of energy that can be harvested depends on factors such as the type of harvester, environmental conditions, and the power requirements of the portable timepiece. As technology advances, energy harvesting technology will be increasingly incorporated into portable timepieces and other electronic devices.

[0004] One of the major difficulties in the optimization of energy harvesting systems is the energy consumption of the integrated circuit (IC) responsible for extracting and managing the harvested energy. This IC plays an important role in making energy harvesting systems practical and efficient, especially in applications such as wearable devices where space and power constraints are important considerations. The development of specialized energy harvesting ICs has contributed to the advancement of self-powered and energy-efficient electronic devices. The traditional approach to ICs often ignores the important aspect of minimizing the power requirements of the IC, resulting in inefficiencies that compromise the overall effectiveness of the energy harvesting system. Excessive energy consumption not only reduces the net energy gain but also limits the feasibility of using energy harvesters in resource-constrained applications. In systems that use a dedicated integrated circuit for the energy harvesting function of external energy, this integrated circuit always consumes energy even when there is no external energy. This reduces the autonomy of the system and the system's power reserve because this integrated circuit is powered by the system's energy accumulator such as a battery. Summary of the Invention Problems to be Solved by the Invention

[0005] An object of the present invention is to solve the above problems related to an integrated circuit used for extracting energy from an energy harvester. In such a situation, the present invention focuses on overcoming the bottleneck of energy consumption by proposing an electronic circuit configuration, also called a circuit or an electronic circuit, which is specially made to have epoch-making high energy efficiency in relation to energy extraction from the harvester. The proposed circuit configuration is designed to operate with a minimum power overhead, ensuring that the energy consumed by the integrated circuit is significantly lower compared to traditional circuits.

[0006] According to a first aspect of the present invention, there is provided a circuit configuration for extracting energy from an energy harvester as recited in claim 1.

[0007] The present invention has the advantage that it can improve the autonomy and power reserve of a system using this circuit configuration while maintaining the ability to optimally harvest energy from an external source using an integrated circuit of the circuit configuration. Further, this circuit configuration not only maximizes the net energy available for consumption, but also extends the operating life of the energy harvesting system, thereby making the energy harvesting system practical and sustainable over a wide range of applications.

[0008] According to a second aspect of the present invention, there is provided a method of operating a circuit configuration for extracting energy from an energy harvester as recited in claim 14.

[0009] Other aspects of the present invention are described in the dependent claims.

[0010] Other features and advantages of the present invention will become apparent by reading the following description of exemplary embodiments with reference to the accompanying drawings.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0012] An embodiment of the present invention will now be described in detail with reference to the accompanying drawings. The present invention will be described in relation to an energy harvesting system for a timepiece, such as a wristwatch. However, the teachings of the present invention are not limited to this environment or application. The same or corresponding functional or structural elements appearing in different figures are assigned the same reference numerals. In this application, "and / or" is used to mean any one or more items in the group joined by "and / or". As an example, "x and / or y" means any element of the 3-element set {(x),(y),(x,y)}. That is, "x and / or y" means "one or both of x and y". As another example, "x, y and / or z" means any element of the 7-element set {(x),(y),(z),(x,y),(x,z),(y,z),(x,y,z)}. That is, "x, y and / or z" further means "one or more of x, y and z". The term "comprising" is used in this application as an open-ended term, i.e., the elements include all elements that are listed and may include additional elements that are not listed. Thus, the term "comprising" is to be interpreted as a broad term that includes, contains, or includes.

[0013] FIG. 1 is a block diagram illustrating an exemplary energy harvesting system 1 according to the present invention. The arrows in FIG. 1 indicate the direction of energy flow. The energy harvesting system 1 includes an energy source or harvester 2. An energy harvester for a watch is a device that captures ambient energy from the environment, converts it into electricity, and supplies the energy to the watch. Traditional watches often use batteries for power, but energy harvesters provide an alternative or supplemental energy source. One or more types of energy harvesters can be used, possibly in combination, and can utilize different environmental energy sources, including: - Solar cells: A portable clock equipped with a solar cell can typically convert light energy from the sun into electricity. The solar cell is usually incorporated into the face of the portable clock. - Kinetic or mechanical energy harvester: This device converts motion or kinetic energy into electricity. In the case of a portable clock, this often involves using a rotor that rotates with the movement of the wearer's wrist to generate electrical energy. - Thermoelectric generator: This harvester converts a temperature difference into electricity. The temperature gradient between the wearer's body and the surrounding environment can be used to generate energy. - Radio frequency (RF) harvester: The RF harvester captures energy from ambient radio frequency signals. This technology is still in its infancy but has the potential to be used in small electronic devices such as portable clocks.

[0014] Energy harvester 2 is connected to energy harvester IC3, which is a component designed to extract energy from energy harvester 2 and manage and optimize this operation and the subsequent processing of the extracted energy. An IC is an assembly of electronic components, in which typically hundreds to millions of transistors, resistors, and capacitors are interconnected on a thin substrate of a semiconductor material (usually silicon) to form small chips or wafers. In this application, the expression "operably connected" can be used synonymously with the term "connected". The main function of IC3 is to efficiently convert and regulate the harvested energy to charge energy accumulator 4. IC3 can have one or more of the following characteristics and functions. - Energy harvesting control: The IC monitors the output of the energy converter (e.g., the voltage from the energy harvester) and controls the harvesting process to maximize efficiency. - Power management: The IC manages the power generated by the energy harvester and ensures that this power is provided to the energy accumulator 4 in a stable and regulated form. This can include voltage regulation, current limiting, and other power management functions. - Energy storage interface: The IC facilitates the charging of the energy accumulator 4, which can be a rechargeable battery or capacitor. - Low-power operation: In energy harvesting applications, where there is often little available power, the IC is designed to operate efficiently at low power levels. This can include a zero-power or substantially zero-power sleep mode. - Adaptive power control: The IC can have an adaptive power control function that adjusts the power supply based on the availability of energy and the power requirements of the components of the energy harvesting system. - Energy monitoring and reporting: The IC can have a function for monitoring and reporting energy harvesting performance. This information is valuable for optimizing the design and knowing the available amount of energy of the device.

[0015] The energy harvesting system 1 includes an energy accumulator 4 which is an energy storage element. Thus, the accumulator used in a portable watch is a component used for energy storage. The energy accumulator can be, for example, a rechargeable battery such as a lithium ion or lithium polymer battery. Alternatively or in addition, the energy accumulator can be a supercapacitor, also called an ultracapacitor, which has a large capacitance value, much higher than that of a solid capacitor, although its voltage limit is low. The energy accumulator fills the gap between an electrolytic capacitor and a rechargeable battery. The energy accumulator typically stores 10 to 100 times more energy per unit volume or weight than an electrolytic capacitor, can be charged and supplied much faster than a battery, and can withstand many more charge and discharge cycles than a rechargeable battery. Thus, the energy accumulator 4 functions as a reservoir for storing the harvested energy. The energy production by the energy harvester may not be constant or may not match the instantaneous power demand of the portable watch. Thanks to the energy accumulator, it becomes possible for the portable watch to store surplus energy during surplus times and release it when needed to power the electronic components of the portable watch.

[0016] According to the present invention, the energy accumulator 4 is connected to the IC3 via a switch 5, and this switch 5 is configured to be selectively opened and closed based on the capabilities of the IC3 so as to extract energy from the energy harvester 2. In particular, the IC3 is configured to output a control signal, which is also called an energy signal and is used to control the operation of the switch as an inverted or non-inverted signal. That is, the control signal is used to control the conductivity of the switch. The control signal (or the absence of the control signal) is configured to disconnect the IC3 from the energy accumulator 4 when the energy harvester is unable to harvest energy. That is, when the IC3 is unable to extract energy from the energy harvester 2, the switch 5 is open, i.e., non-conductive. As soon as the energy harvester is able to harvest energy or as soon as the IC is able to extract energy from the energy harvester 2, the switch 5 is closed, i.e., made conductive, so as to enable the IC to charge the energy accumulator. When the IC3 is disconnected from the energy accumulator 4, the IC3 stops consuming energy or the energy consumption of the IC3 is substantially negligible. When the IC is connected to the energy accumulator, the consumption of the IC is covered by the energy extracted from the harvester, and if there is surplus energy, it is used to charge the energy accumulator. Instead of providing only one switch between the IC3 and the energy accumulator 4, a plurality of switches forming a switch system can be provided. In this case, these switches operate in a controlled manner so as to collectively disconnect the IC from the energy accumulator or to collectively connect the IC3 to the energy accumulator 4 based on one or more control signals from the IC3.

[0017] The control signal may be a digital signal or an analog signal. In this specification, the term "signal" should be understood broadly, as information may in some cases be typically encoded in a signal. In the example of FIG. 2, an analog signal is used. When IC3 can extract energy from energy harvester 2, the first output node or terminal 6, denoted as VSUP in FIG. 2, is set to a high voltage value V DD and when energy cannot be extracted from the energy harvester, it is set to a low voltage value V SS , which is zero in this case.

[0018] In this example, switch 5 is implemented as a transistor, specifically as a p-type metal oxide semiconductor field effect transistor. To close the p-MOSFET switch, a low voltage needs to be applied to the gate terminal of the PMOS transistor such that the voltage between the gate and source terminals becomes negative. The PMOS transistor operates to create a conductive channel between the source and drain terminals when a low voltage (lower than the source voltage) is applied to the gate terminal. In this situation, the voltage difference (V gs ) between the gate and source is negative, which causes the PMOS transistor to turn on and allows current to flow from the source to the drain. For this purpose, the energy harvesting system 1 in this case can further include a logic circuit 7, also called an inverter circuit 7, which is arranged between IC3 and switch 5 and inverts the control signal before the inverted control signal is applied to the switch.

[0019] Figure 1 further shows a portable clock system 8, which can also be understood as being part of the energy harvesting system 1, or alternatively, as being connected to the energy harvesting system 1 rather than being part of it. The portable clock system forms a load of the energy harvesting system and includes the electronic components of a portable clock that is powered by an energy accumulator. For this purpose, as shown in Figure 1, the portable clock system is connected to the energy accumulator. In particular, unlike traditional energy harvesting systems, in this case, the portable clock system 8 is directly connected to the energy accumulator so that the portable clock system is not connected to the energy accumulator via the IC3.

[0020] Figure 2 is a circuit diagram showing details of an implementation example of the energy harvesting system 1 of FIG. 1. The energy harvesting system 1, specifically IC3, further includes a reserve energy storage element 9, which in this example is a capacitor called the first capacitor. In this example, the first capacitor is a short-term storage capacitor for temporarily storing electrical energy. The purpose of the first capacitor is to contribute to the autonomous power-on of IC3 when IC3 is not connected to the energy accumulator 4. Thus, thanks to the first capacitor 9, the IC has an internal capacitance large enough to autonomously power itself for a short period of time. That is, the IC can autonomously power on by using only the energy provided by the energy harvester 2 and the first capacitor 9. Thus, IC3 is configured to self-power during sleep mode when there is no energy from the energy harvester and thus not use the energy from the energy accumulator 4. As soon as IC3 powers on, a control signal representing the output voltage of the IC indicates that external energy is available and that the IC is operable to extract that energy from the energy harvester 2.

[0021] In the configuration of FIG. 2, IC3 is connected to a solar cell, which has two main nodes or terminals, a positive one called HRV+ and a negative one called HRV-. These terminals represent the electrical contacts of the solar cell through which the generated current flows. As shown in FIG. 2, an inductor 10, also called a coil, is connected to the positive terminal of the solar cell. Inductor 10 is part of a voltage converter circuit, which in this case is a step-up circuit configured to increase the voltage level of the input signal. This is commonly also called a boost converter or voltage booster. The step-up circuit is particularly useful in situations where a higher voltage than the initially available voltage is required. Inductor 10 forms the core of the step-up circuit such that it stores energy in its magnetic field when current flows through the inductor.

[0022] This operates in the following two stages. In the first stage, energy from the input source is stored in the magnetic field of the inductor, and in the second stage, the magnetic field decays and gradually transfers the energy to an element connected to the output. In this latter second stage, a voltage drop across the inductance is added to the input voltage, resulting in a higher output voltage.

[0023] The energy harvesting system 1 further includes a second capacitor 11, also called a first additional or auxiliary energy storage element, and a third capacitor 12, also called a second additional or auxiliary energy storage element. In this example, the second capacitor is connected to the positive terminal of the solar cell (or more generally, the energy harvester), and in this example, the third capacitor is connected to the output node 6 of the IC. The second and third capacitors are used in this circuit to smooth out voltage fluctuations and thus prevent the voltage in the circuit from becoming too high.

[0024] In this example, the inverter circuit 7 uses complementary metal-oxide-semiconductor (CMOS) technology. As shown in FIG. 2, the CMOS inverter consists of both a p-type metal-oxide-semiconductor (PMOS) transistor 13 and an n-type metal-oxide-semiconductor (NMOS) transistor 14. By using both types of transistors, efficient signal conversion becomes possible. The inverter circuit 7 is configured to invert the state or logic level of a signal to the opposite state or logic level. Thus, when a LOW signal is applied to the inverter circuit 7, the inverter circuit 7 inverts it to a HIGH signal. On the other hand, when a HIGH signal is applied to the inverter circuit 7, the inverter circuit 7 inverts it to a LOW signal.

[0025] As in this example, the portable clock is an electronic portable clock, and in particular, a quartz portable clock. The portable clock system 8 includes a portable clock system IC 15 and a motor 16. The energy accumulator 4 powers the portable clock system IC 15 that includes a quartz crystal oscillator. The portable clock system IC accurately measures time using the oscillation of the quartz crystal and sends a signal to the motor 16 to drive the hands of the portable clock.

[0026] The flowchart of FIG. 3 summarizes the operation of the energy harvesting system 1. In step 31, IC3 detects that external energy has become available and exits the sleep mode by powering on using the energy from the first capacitor 9 and the energy harvester 2. In step 32, IC3 starts extracting energy from the energy harvester 2. In step 33, the IC generates a control signal or an energy signal. In this example, this is a HIGH signal indicating that the IC is operational and can extract energy from the energy harvester. In step 34, the control signal is processed (inverted or not inverted) by the inverter circuit 7 to control the switch 5. In particular, the inverter circuit inverts the control signal, which is used to control the operation and conductivity of the switch 5. Thus, in step 35, the inverted control signal is applied to the gate terminal of the switch, causing the switch to close. In step 36, the IC charges the energy accumulator through the closed switch using the energy extracted from the energy harvester 2. In step 37, IC3 determines whether external energy is still available. If the result is positive, the process continues in step 36 by further charging the energy accumulator. When it is determined in step 37 that the external energy is not available, in step 38, IC3 sets the control signal to a low value (LOW signal). This indicates that it is no longer possible to extract energy from the energy harvester 2. In step 39, the switch 5 opens when a HIGH signal is applied to the gate terminal of the switch 5. In step 40, the IC powers down and enters the sleep mode until it can extract energy from the energy harvester 2 again. Note that in the above process, the order of steps 32 and 33 can be reversed, or these steps can be executed simultaneously or substantially simultaneously.

[0027] Although the present invention has been described in detail in the above description with reference to the drawings, such drawings and descriptions should be considered as illustrative and exemplary, and not as limiting the present invention. The present invention is not limited to the disclosed embodiments. A person skilled in the art can understand and achieve other embodiments and variations based on the consideration of the drawings, the specification, and the claims when implementing the present invention.

[0028] In the claims, the term "comprising" does not exclude the presence of other elements or steps, nor does it exclude the existence of a plurality even if in singular form. Just because different features are described in different dependent claims does not mean that the combination of these features cannot be used advantageously. The reference signs in the claims should not be construed as limiting the scope of the present invention.

Explanation of Reference Signs

[0029] 1 Circuit configuration 2 Energy harvester 3 Integrated circuit 4 Energy accumulator 5 Switch 7 Logic circuit 8 Load 9 Reserve energy storage element 13, 14 Complementary metal oxide semiconductor circuit

Claims

1. A circuit arrangement (1) for harvesting energy from an energy harvester (2), comprising: an integrated circuit (3) connected to the energy harvester (2) and configured to extract energy from the energy harvester (2); an energy accumulator (4) connected to the integrated circuit (3) and configured to receive the energy extracted by the integrated circuit (3); a switch (5) disposed between the integrated circuit (3) and the energy accumulator (4) for selectively disconnecting the energy accumulator (4) from the integrated circuit (3); The integrated circuit (3) is configured to output a control signal as an inverted or non-inverted signal; The control signal is configured to close the switch (5) when the integrated circuit (3) is able to extract energy from the energy harvester (2) and to open the switch (5) when the integrated circuit (3) is unable to extract energy from the energy harvester (2), thereby disconnecting the integrated circuit (3) from the energy accumulator (4). A circuit configuration (1).

2. The circuit arrangement (1) further comprises a load (8) powered by the energy accumulator (4), The load (8) is connected to the energy accumulator (4) such that the load (8) is not connected to the energy accumulator (4) through the integrated circuit (3).

2. A circuit arrangement (1) according to claim 1 .

3. The load (8) is directly connected to the energy accumulator (4).

2. A circuit arrangement (1) according to claim 1 .

4. The load (8) includes a portable clock system.

3. A circuit arrangement (1) according to claim 2.

5. The circuit configuration (1) further includes a logic circuit (7) disposed between the integrated circuit (3) and the switch (5) for processing a control signal provided to the switch (5).

2. A circuit arrangement (1) according to claim 1 .

6. The logic circuit is an inverter circuit (7) using complementary metal oxide semiconductor circuits (13, 14).

6. A circuit arrangement (1) according to claim 5.

7. The switch (5) is a P-channel metal oxide semiconductor field effect transistor.

2. A circuit arrangement (1) according to claim 1 .

8. The integrated circuit (3) includes or is connected to an auxiliary energy storage element (9), The reserve energy storage element (9) contributes to powering the integrated circuit (3) after it has been powered off, making it possible to extract energy from the energy harvester (2).

2. A circuit arrangement (1) according to claim 1 .

9. The reserve energy storage element (9) is a short-term storage capacitor.

9. A circuit arrangement (1) according to claim 8, characterized in that

10. The integrated circuit (3) cannot be powered by the energy accumulator (4) when the switch (5) is open.

2. A circuit arrangement (1) according to claim 1 .

11. The circuit arrangement (1) further includes a step-up circuit configured to increase a voltage level at an output node of the energy harvester (2).

2. A circuit arrangement (1) according to claim 1 .

12. The control signal has a high signal value when the integrated circuit (3) is able to extract energy from the energy harvester (2) and a low signal value when the integrated circuit (3) is unable to extract energy from the energy harvester (2).

2. A circuit arrangement (1) according to claim 1 .

13. the energy harvester (2) is at least one of a solar cell, a kinetic or mechanical energy harvester, a thermoelectric generator, and a radio frequency harvester; and / or The energy accumulator (4) is a rechargeable battery and / or a supercapacitor.

2. A circuit arrangement (1) according to claim 1 .

14. A method of operating a circuit arrangement (1) for harvesting energy from an energy harvester (2), comprising: The circuit configuration is an integrated circuit (3) connected to the energy harvester (2) and configured to extract energy from the energy harvester (2); an energy accumulator (4) connected to the integrated circuit (3) for receiving the energy extracted by the integrated circuit (3); a switch (5) disposed between the integrated circuit (3) and the energy accumulator (4) for selectively disconnecting the energy accumulator (4) from the integrated circuit (3); The method comprises: powering (31) said integrated circuit (3) without drawing energy from said energy accumulator (4) in order to power on said integrated circuit (3) as soon as it is possible to draw energy from said energy harvester (2); harvesting (32) energy from the energy harvester (2) by means of the integrated circuit (3); generating (33) a control signal for controlling the operation of the switch (5) by the integrated circuit (3); closing (35) the switch (5) when the control signal is applied to the switch (5) to control the integrated circuit (3) as inverted or non-inverted, which indicates that the integrated circuit (3) can harvest energy from the energy harvester (2); and charging (36) the energy accumulator (4) through the closed switch (5) by the integrated circuit (3). A method comprising:

Images