Method and apparatus for energy harvesting and charging a rechargeable energy storage device

Abstract

The present invention relates to a method for energy harvesting and charging an energy storage device. The method uses a voltage converter system and comprises the following steps: monitoring a parameter V indicating a charge level of a first rechargeable storage device Batt1 , and the parameter V Batt1 The method further comprises the steps of charging a second rechargeable storage device and operating the voltage converter system to transfer charge from the second rechargeable storage device to the first rechargeable storage device. The present invention also relates to an integrated circuit for energy harvesting, wherein a terminal connectable to the second rechargeable storage device is switchably coupled to an input terminal and an output terminal of the voltage converter system.

Description

Field of the Invention

[0001] The present invention relates to a method and apparatus for energy harvesting. More particularly, the present invention relates to a method and apparatus for charging a rechargeable energy storage device.

[0002] Description of the prior art

[0003] The use of a voltage converter to extract energy from an energy harvester and to charge an energy storage device is well known in the art. For example, in WO 2018234485, an integrated circuit including a voltage converter is described for transferring energy from an energy harvester to a rechargeable storage device. The energy stored in the rechargeable storage device is then used as a power source for an application load. The application load may be coupled directly or indirectly to the storage device. Indirect coupling is established, for example, by placing an auxiliary voltage converter between the storage device and the application load, and wherein the auxiliary voltage converter is configured to regulate a specific voltage required by the application load.

[0004] A variety of energy harvesters can be used as energy sources, such as photovoltaic cells (PV), thermoelectric generators (TEG), piezoelectric energy generators and electromagnetic energy generators. Rechargeable storage devices are for example rechargeable batteries such as lithium-ion batteries, supercapacitors or conventional capacitors.

[0005] One of the problems with known energy harvesting systems is that when initially starting with a depleted rechargeable storage device, it takes a long time to initially charge the rechargeable storage device with energy from the energy harvester. As a result, it also takes a long time for the application load to receive power from the rechargeable storage device and begin to operate. In particular, if the rechargeable storage device is a supercapacitor that has a voltage of zero volts when fully discharged, the charging time of the supercapacitor may be very long. Moreover, it may also take a considerable charging time to charge the rechargeable battery to the required charge level to be ready to power the application load for a sufficiently long period of time.

[0006] The second issue is related to the variable conditions inherent in energy harvesting systems, which can cause the energy harvester to not be able to continuously provide energy over longer periods of time, such as multiple days. Depending on the type of energy harvester, energy harvesting may be interrupted for considerable intervals, such as several hours, which can reduce the reliability and long-term functionality of the application load. Depending on the power consumption of the application load, this may cause the application load to stop functioning.

[0007] For the second problem, backup systems have been proposed in which, for example, a primary battery is connected to the application load during time intervals when the energy harvester is not supplying energy. SUMMARY OF THE INVENTION

[0009] The object of the present invention is to provide a method and a device for energy harvesting and charging a rechargeable storage device in an efficient manner, so that an application load coupled to the rechargeable storage device to receive power can start operating more quickly, i.e. within a few minutes, even in the case where the rechargeable storage device is initially completely exhausted. Another object is that the application load can continue to operate even in the case of an interruption of the energy harvester for a longer period of time, such as an interruption of several hours or even days. It is also an object to maximize the energy extracted and used from the energy harvester.

[0010] The invention is defined in the appended independent claim. The dependent claims define advantageous embodiments.

[0011] According to a first aspect of the present invention, a method for energy harvesting and supplying power to an application load is provided. The application load powered by the harvested energy may be any type of application such as a portable device, a sensor, an external circuit or a wireless transmitter.

[0012] The method for energy harvesting according to the invention uses a voltage converter system to convert input power into output power and to charge at least a first rechargeable storage device and a second rechargeable storage device. Typically, the voltage converter system comprises one or more voltage converters.

[0013] The method according to the present invention comprises the following steps: coupling a first power input path between an energy harvester and a voltage converter system to transfer input power from the energy harvester to the voltage converter system; monitoring parameters V indicating charge levels of the first rechargeable storage device and the second rechargeable storage device, respectively; Batt1 and parameter V Batt2 ; and coupling the first rechargeable storage device to the application load so that the first rechargeable storage device can power the application load when being charged.

[0014] In an embodiment, the parameter V Batt1 and V Batt2 and V respectively correspond to the voltages of the first rechargeable storage device and the second rechargeable storage device. Batt1 and V Batt2 The first accumulated charge and the second accumulated charge respectively correspond to, for example, the first and second accumulated charges acquired by a charge counter that counts the accumulated charge during the charging process of the first and second rechargeable storage devices.

[0015] The method further comprises the step of coordinating the charging of the first rechargeable storage device and the second rechargeable storage device by repeatedly performing the following sub-steps:

[0016] 1a) coupling a first power output path between the voltage converter system and the first rechargeable storage device to transfer output power from the voltage converter system to the first rechargeable storage device,

[0017] 2a) operating the voltage converter system to charge the first rechargeable storage device with energy from the energy harvester until the parameter V Batt1 Reaching the upper threshold V Batt1-up ,

[0018] and wherein charging the first rechargeable storage device with energy from the harvester comprises transferring charge from the energy harvester to the first rechargeable storage device,

[0019] 3a) If V Batt1 The upper threshold V has been reached Batt1-up , and if V Batt2 Below the upper threshold V Batt2-max ,but

[0020] i) decoupling the first power output path and coupling the second power output path between the voltage converter system and the second rechargeable storage device to transfer output power from the voltage converter system to the second rechargeable storage device, and

[0021] ii) operating the voltage converter system to charge the second rechargeable storage device with energy from the energy harvester,

[0022] and wherein charging the second rechargeable storage device with energy from the harvester comprises transferring charge from the energy harvester to the second rechargeable storage device,

[0023] 4a) If during charging of the second rechargeable storage device the parameter V Batt1 Then from the upper threshold V Batt1-up Falls to the lower threshold V Batt1-low , where V Batt1-low <V Batt1-up , then disconnect the second power output path and restart step 1a).

[0024] The method according to the invention further comprises the following step: if i) the parameter V of the first rechargeable storage device Batt1 Has dropped to the critical threshold V Batt1-SW Below, where V Batt1-SW <V Batt1-low , and if ii) the parameter V Batt2 Equal to or above a predefined threshold V Batt2-low, then energy is transferred from the second rechargeable storage device to the first rechargeable storage device. The step of transferring energy includes the following sub-steps: 1b) decoupling the first power input path, 2b) coupling the second power input path between the second rechargeable storage device and the voltage converter system to transfer input power from the second rechargeable storage device to the voltage converter system, and 3b) operating the voltage converter system to charge the first rechargeable storage device with energy from the second rechargeable storage device until the parameter V of the first rechargeable storage device is equal to Batt1 The upper threshold V has been reached Batt1-up .

[0025] Advantageously, by during the discharge phase of the first rechargeable storage device, ie at V Batt1 From the upper threshold V Batt1-up Falls to the lower threshold V Batt1-low During the charging of the second rechargeable storage device, the application load can continue to operate throughout the entire charging process of the second rechargeable storage device and the entire process of repeated recharging of the first rechargeable storage device. In this way, the use of the application load does not interfere with or interrupt the energy collection and energy storage in the second rechargeable storage device.

[0026] Advantageously, when the energy harvester is not operating, the second rechargeable storage device may be used to recharge the first storage device.

[0027] Advantageously, when the energy harvester is not operating, the voltage converter system is used to transfer charge from the second rechargeable storage device to the first rechargeable storage device by coupling the second power input path between the second rechargeable storage device and the voltage converter system. Thus, the second rechargeable storage device can be a dedicated storage device that operates at, for example, a different maximum voltage than the first rechargeable storage device and has a large energy storage capacity. The two storage devices can also be made of different technologies, the first rechargeable storage device can be, for example, a rechargeable battery such as a lithium-ion battery, and the second rechargeable storage device can be, for example, a supercapacitor. In this way, if the energy harvester is interrupted for a long time, the energy stored in the second rechargeable storage device can be transferred to the first rechargeable storage device and used to continue to power the application load.

[0028] Preferably, the energy storage capacity of the second rechargeable storage device is more than five times greater, more preferably more than ten times greater than the energy storage capacity of the first rechargeable storage device.

[0029] According to a second aspect of the present invention, an integrated circuit for energy harvesting is provided. The integrated circuit for energy harvesting includes: a voltage converter system, the voltage converter system is suitable for converting input power into output power to charge at least two rechargeable storage devices; a first terminal, the first terminal can be connected to an energy harvester; a second terminal, the second terminal can be connected to a first rechargeable storage device; a third terminal, the third terminal can be connected to a second rechargeable storage device; a controller, the controller is used to control the voltage converter system; a plurality of power input paths, the plurality of power input paths at least include a first power input path for transferring input power from the first terminal to the voltage converter system; a plurality of power output paths, the plurality of power output paths at least include a first power output path for transferring output power from the voltage converter system to the second terminal and a second power output path for transferring output power from the voltage converter system to the third terminal; and a monitoring unit, the monitoring unit is coupled to the controller and is configured to monitor parameters V indicating the charging levels of the first rechargeable storage device and the second rechargeable storage device, respectively, when the first rechargeable storage device and the second rechargeable storage device are connected to the second terminal and the third terminal, respectively. Batt1 and parameter V Batt2 .

[0030] In an embodiment, the parameter V Batt1 and parameter V Batt2 Corresponding to, for example, voltages sensed at the second terminal and the third terminal, respectively.

[0031] The integrated circuit for energy harvesting according to the present invention is characterized in that the plurality of power input paths include a second power input path for transmitting input power from the third terminal to the voltage converter system, and characterized in that the voltage converter system includes: an input selection circuit for selecting a power input path from the plurality of power input paths to receive input power via the selected power input path; and an output selection circuit for selecting a power output path from the plurality of power output paths to output output power via the selected power output path, and characterized in that the controller is configured to select a power output path from the plurality of power output paths based on the parameter V Batt1 The comparison with the first predefined threshold value and / or the parameter V Batt2The controller can form a plurality of specific combinations of power input paths and power output paths and switch between the plurality of specific combinations by comparing the control logic with the second predefined threshold value. The specific combinations of the controller can form and switch between the following combinations: i) a first combination formed by selecting the first power input path and selecting the first power output path, ii) a second combination formed by selecting the first power input path and selecting the second power output path, and iii) a third combination formed by selecting the second power input path and selecting the first power output path.

[0032] Selecting "one (a)" power input path from a plurality of power input paths to receive input power via the selected power input path must be interpreted as selecting "one" power input path from a plurality of power input paths so as to receive input power only via the selected power input path. Similarly, selecting "one (a)" power output path from a plurality of power output paths to output output power via the selected power output path must be interpreted as selecting "one" power output path from a plurality of power output paths so as to output output power only via the selected power output path.

[0033] Advantageously, by providing a second power input path for transferring input power from the third terminal to the voltage converter system, the second rechargeable storage device coupled to the third terminal can not only be charged with energy from the energy harvester to form an energy storage, but can also be used as an alternative energy source to charge the first rechargeable storage device when the energy harvester is not operating. In fact, since the third terminal is also coupled to the voltage converter system to provide input power, the voltage converter system can be used to transfer charge from the second rechargeable storage device coupled to the third terminal to the first rechargeable storage device coupled to the second terminal. In this way, the first storage device can continue to charge even if the energy harvester is not operating, so that the application load coupled to the first storage device can continue to operate.

[0034] In an embodiment, the controller of the integrated circuit is further configured to: if the parameter V Batt1 becomes equal to or greater than the upper threshold V Batt1-up , and if the parameter V Batt2 Below the upper threshold V Batt2-max , then switch from the first combination to the second combination; if the parameter V Batt1 From the upper threshold V Batt1-up Falls to the lower threshold V Batt1-low , where V Batt1-low <V Batt1-up , then switch from the second combination to the first combination, and if the parameter V Batt1 From the lower threshold V Batt1-low drops to the critical threshold VBatt1-SW , where V Batt1-SW <V Batt1-low , and if V Batt2 Above the lower threshold V Batt2-low , where V Batt2-low <V Batt2-max , then switch from the first combination to the third combination.

[0035] In an embodiment, the integrated circuit includes a fourth terminal that can be connected to an auxiliary energy source such as a primary battery, and the multiple power input paths include a third input path for transferring input power from the fourth terminal to the voltage converter system, and wherein the specific combination of input / output paths includes a fourth combination formed by selecting the third power input path and selecting the first power output path.

[0036] In further embodiments, the voltage converter system includes a voltage converter for converting input power received via a selected power input path into output power output via a selected power output path, and wherein the voltage converter is one of: a boost voltage converter, a buck voltage converter, or a buck-boost voltage converter. In other words, in these embodiments, a single voltage converter is used in combination with an input selection circuit and an output selection circuit.

[0037] BRIEF DESCRIPTION OF THE DRAWINGS

[0038] These and further aspects of the invention will be explained in more detail by way of example and with reference to the accompanying drawings, in which:

[0039] Figure 1a schematically illustrates an example of an energy harvesting system according to the present disclosure,

[0040] Figure 1b Schematically showing another example of an energy harvesting system according to the present disclosure,

[0041] Figure 2 A charging process of a first rechargeable storage device and a second rechargeable storage device using the method according to the invention is shown,

[0042] Figure 3 Schematically illustrating an energy harvesting system including an integrated circuit according to the present invention,

[0043] Figure 4a An example of a voltage converter system according to the invention is shown, the voltage converter system comprising a buck / boost voltage converter,

[0044] Figure 4bAn example of a voltage converter system according to the invention is shown, the voltage converter system comprising two buck / boost voltage converters,

[0045] Figure 5 An example of a voltage converter system according to the present invention is shown, the voltage converter system comprising an input selection circuit for selecting between three power input paths and an output selection circuit for selecting between three power output paths,

[0046] Figure 6a An embodiment of a voltage converter system comprising two voltage converters is shown,

[0047] Figure 6b An alternative embodiment of a voltage converter system comprising two voltage converters is shown,

[0048] Figure 7 An embodiment of a voltage converter system comprising three voltage converters is shown,

[0049] Figure 8 An embodiment of a voltage converter system is shown that includes three voltage converters and includes an input selection circuit for selecting between three power input paths and an output selection circuit for selecting between two power output paths.

[0050] The accompanying drawings are neither drawn to scale nor to proportion. Generally, in the accompanying drawings, like parts are represented by like reference numerals.

[0051] Detailed description of embodiments of the present invention

[0052] The present disclosure will be described in terms of specific embodiments, which are illustrative of the present disclosure and should not be construed as limiting. It will be appreciated by those skilled in the art that the present disclosure is not limited to what has been specifically shown and / or described, and alternative or modified embodiments may be developed based on the overall teachings of the present disclosure. The accompanying drawings described are merely illustrative and non-limiting.

[0053] Use of the verb "comprise" and its conjugations does not exclude the presence of elements other than those stated.

[0054] Furthermore, the terms first, second, etc. in the specification and in the claims are used to distinguish similar elements and not necessarily to describe a sequence in time, space, level, or in any other manner. It should be understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the disclosure described herein are capable of operation in other sequences than those described or illustrated herein.

[0055] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present disclosure. Thus, the phrases "in one embodiment" or "in an embodiment" appearing in various places throughout this specification do not necessarily all refer to the same embodiment, but may do so. Additionally, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art in light of this disclosure.

[0056] According to a first aspect of the present invention, a method for energy harvesting and supplying power to an application load is provided. The method for energy harvesting uses a system for energy harvesting including a voltage converter system.

[0057] A voltage converter system must be interpreted as a system for converting input power received from an energy source into output power for charging a storage device. An energy source (e.g., an energy harvester) receives an input voltage V in The input power is supplied, and the voltage converter system outputs a voltage V corresponding to the voltage of the storage device. out Output Output power. Input voltage V in Can be higher or lower than the output voltage V out Typically, the voltage converter system includes one or more voltage converters, and specific embodiments of various voltage converter systems are further described below. Examples of voltage converters are a DC-DC boost converter, a DC-DC buck converter, or a DC-DC buck / boost converter. Typically, the voltage converter system is part of an integrated circuit, often referred to as a power management integrated circuit (PMIC).

[0058] Figure 1a , an example of a system 100 for energy harvesting is schematically shown. The system includes a power management integrated circuit (PMIC) 1, which includes a voltage converter system 20 and a controller 40 for controlling the voltage converter system. An energy harvester 70 is coupled to a first terminal 11, which is used to generate an energy harvester with an input voltage V in The PMIC 1 includes an input terminal 12 that receives power from an energy harvester. The PMIC 1 includes a second terminal 12 that is an output terminal coupled to a first rechargeable storage device 50. In this example, the application load 90 is coupled to the first storage device 50 in a direct connection. In other embodiments, a voltage regulator may be placed, for example, between the first storage device and the application load to generate a voltage required by the application load that is different from the voltage of the first storage device. Figure 1a The PMIC shown comprises a third terminal 13 connected to a second rechargeable storage device 60 .

[0059] The first rechargeable storage device is, for example, a rechargeable battery, a capacitor, or a supercapacitor. Similarly, the second rechargeable storage device may also be a rechargeable battery, a capacitor, or a supercapacitor.

[0060] exist Figure 1b , another example of a system for energy harvesting is schematically shown, wherein a first application load 90a is coupled to a first storage device 50, and wherein a second application load 90b is coupled to a second storage device 60. The first application load is, for example, a low power load, such as for monitoring purposes, and the second application load is, for example, a higher power load, such as for a communication device or an actuation device.

[0061] The method for energy harvesting according to the present invention comprises the following steps: coupling a first power input path between the energy harvester and the voltage converter system to transfer the input power from the energy harvester to the voltage converter system 20; monitoring parameters V respectively indicating the charge levels of the first rechargeable storage device 50 and the second rechargeable storage device 60; Batt1 and parameter V Batt2 ; and coupling the first rechargeable storage device to the application load 90 so that the first rechargeable storage device can power the application load when being charged.

[0062] In an embodiment, the parameter V obtained by voltage measurement Batt1 and V Batt2 and V respectively correspond to the voltages of the first rechargeable storage device and the second rechargeable storage device. Batt1 and V Batt2 Corresponds to the amount of charge acquired by the charge counter.

[0063] When the first storage device is fully charged, such as reaching the upper threshold voltage V Batt1-up As indicated, the first rechargeable storage device 50 can be used as a power source for the application load 90. The voltage threshold V Batt1-up It does not necessarily correspond to a fully charged storage device, but it may be a value that indicates that the first storage device is sufficiently charged to begin supplying power to the application load.

[0064] The method according to the invention further comprises the step of coordinating the charging of the first rechargeable storage device and the second rechargeable storage device by repeatedly performing the sub-steps 1 a) to 4a) outlined below.

[0065] Sub-step 1a) corresponds to coupling a first power output path between the voltage converter system and the first rechargeable storage device to transfer output power from the voltage converter system to the first rechargeable storage device.

[0066] Sub-step 2a) corresponds to: operating the voltage converter system to charge the first rechargeable storage device with energy from the energy harvester until the parameter V Batt1 Reaching the upper threshold V Batt1-up Thus, during charging of the first rechargeable storage device, charge is transferred from the energy harvester to the first rechargeable storage device.

[0067] If V Batt1 The upper threshold V has been reached Batt1-up and V Batt2 Below the upper threshold V Batt2-max , then performing sub-step 3a), which corresponds to: i) disconnecting the first power output path and coupling the second power output path between the voltage converter system 20 and the second rechargeable storage device 60 to transfer the output power from the voltage converter system to the second rechargeable storage device, and ii) operating the voltage converter system to charge the second rechargeable storage device with energy from the energy harvester. Therefore, during the charging of the second rechargeable storage device, the charge is transferred from the energy harvester to the second rechargeable storage device.

[0068] Sub-step 4a) corresponds to: if during charging of the second rechargeable storage device, the parameter V Batt1 Then from the upper threshold V Batt1-up Falls to the lower threshold V Batt1-low , where V Batt1-low <V Batt1-up , then disconnect the second power output path and restart step 1a).

[0069] Thus, by repeatedly performing sub-steps 1a) to 4a), the second rechargeable storage device 60 is charged while the charge level of the first rechargeable storage device 50 is maintained at V Batt1-low With V Batt1-up between.

[0070] exist Figure 2 In FIG. 1 , a process for charging a first rechargeable storage device and a second rechargeable storage device according to the method of the present disclosure is shown. Parameter V Batt1 and V Batt2 The variation of is shown as a function of time, showing the charging and discharging of the first rechargeable storage device and the second rechargeable storage device, respectively. Figure 2 As shown, by executing the above sub-steps 1a) to 4a), the parameter V of the first storage device 50 is Batt1 Keep at the lower threshold V Batt1-low With the upper threshold V Batt1-upThe first storage device 50 is kept charged during this time, and the second storage device 60 is charged in parallel with energy from the energy harvester while the first storage device 50 is supplying power to the application load.

[0071] While the second storage device 60 is being charged, the application load continues to operate, so that the operation of the application load is not interrupted. Figure 2 The example shown schematically shows that the time periods when the application load is turned on and off are indicated by "APPL.ON" and "APPL.OFF", respectively. When the application load is turned on and the second rechargeable storage device is being charged, the parameter V Batt1 From the upper threshold V Batt1-up Falls to the lower threshold V Batt1-low As indicated, the first storage device is discharging. Batt1-low Typically, it is a value selected so that the first storage device is still sufficiently charged to provide power to the application load. The values ​​selected for the lower and upper thresholds of the first storage device depend on the type of storage device used, such as a rechargeable battery or a capacitor or a supercapacitor. The upper threshold V Batt1-up is not necessarily equal to the maximum allowable voltage value V of the first rechargeable storage device Batt1-max , V Batt1-up can be, for example, less than V Batt1-max The value of .

[0072] The method according to the present disclosure is characterized in that the method comprises the further step of: if i) the parameter V of the first rechargeable storage device Batt1 Has dropped to the critical threshold V Batt1-SW Below, where V Batt1-SW <V Batt1-low , and if ii) the parameter V Batt2 Equal to or above a predefined threshold V Batt2-low , then energy is transferred from the second rechargeable storage device to the first rechargeable storage device. Predefined threshold V Batt2-low is a value indicating that the second rechargeable storage device is charged to a minimum charge level allowing charge to be transferred from the second rechargeable storage device to the first rechargeable storage device.

[0073] The step of transferring energy from the second rechargeable storage device to the first rechargeable storage device comprises the following sub-steps: 1b) decoupling the first power input path, 2b) coupling the second power input path between the second rechargeable storage device and the voltage converter system to transfer input power from the second rechargeable storage device to the voltage converter system, and 3b) operating the voltage converter system to charge the first rechargeable storage device with energy from the second rechargeable storage device until the parameter V of the first rechargeable storage device is equal to or greater than 100%. Batt1 The upper threshold V has been reached Batt1-up .

[0074] In an embodiment, the parameter V Batt1 The upper threshold V has been reached Batt1-up In the case of a power supply being connected to the second rechargeable storage device 60, transferring energy from the second rechargeable storage device 60 to the first rechargeable storage device 50 comprises a further sub-step 4b). Sub-step 4b) corresponds to performing at least one or a combination of the following steps: i) disconnecting the first power output path 32a and / or disconnecting the second power input path 31b, ii) coupling the first power input path 31a and coupling the second power output path 32b, iii) stopping operation of the voltage converter system 20.

[0075] Where step ii) of coupling the first power input path 31a and coupling the second power output path 32b is applied in sub-step 4b), then if the energy harvester is providing power, the second rechargeable storage device will continue to charge with energy from the energy harvester.

[0076] Figure 2 It is also shown that when the parameter V of the first storage device 50 Batt1 has dropped to the critical threshold level V Batt1-SW The energy transfer from the second storage device to the first storage device is as follows. Parameter V Batt1 This drop in typically occurs when the energy harvester is turned off or when the application load consumes more power than the energy harvester can supply. Figure 2 As shown, when the energy harvester switches from the on state indicated by “EHON” to the off state indicated by “EHOFF”, neither the first storage device nor the second storage device can be charged with energy from the energy harvester. Therefore, when the application load is on and thus consumes power, V Batt1 The voltage drops to V Batt1-low will continue to decrease further until it reaches V Batt1-SW .like Figure 2 As shown, when V Batt1 Down to V Batt1-SWThe first storage device is then recharged using energy from the second storage device, and when the energy harvester again becomes operational and powered, the energy from the energy harvester is again used to maintain the charge on the first storage device and continue charging the second storage device as discussed above.

[0077] By operating the voltage converter system to transfer energy from the second storage device to the first storage device, the voltages of the first storage device and the second storage device can be independent of each other, and the first storage device and the second storage device can also be made of different technologies. For example, the first rechargeable storage device can be a lithium-ion battery operating between 3.6V and 4.0V, while the second rechargeable storage device can be a supercapacitor that can be recharged to a maximum voltage of 2.7V.

[0078] Preferably, the energy storage capacity of the second rechargeable storage device 60 is more than five times, preferably more than ten times, greater than the energy capacity of the first rechargeable storage device 50. In this way, the second storage device forms a large energy storage device suitable for maintaining normal operation of the application load under conditions where the energy harvester is shut down for a longer period of time. By using a first storage device with a smaller energy storage capacity, it will also take less time to charge the first storage device and start operating the application load.

[0079] The second parameter V Batt2 allows determining whether the second storage device is sufficiently charged to provide output power, and this can be done, for example, by setting V Batt2 With the predefined threshold V Batt2-low is compared to determine, where if V Batt2 ≥V Batt2-low , it is considered that the second storage device has been charged.

[0080] If V Batt2 <V Batt2-low , it is considered that the second storage device is not fully charged to supply output power.

[0081] In an embodiment, if an event occurs where V Batt2 The upper threshold V has been reached Batt2-max , the step of charging the first rechargeable storage device 50 and the second rechargeable storage device 60 comprises a further sub-step 3a)iii). Sub-step 3a)iii) corresponds to performing at least one of the following: a) disconnecting the second power output path 32b and / or disconnecting the first power input path 31a, b) stopping the operation of the voltage converter system 20, c) coupling the first power input path 31a and coupling the first power output path 32a.

[0082] In some embodiments, prior to performing the step of coordinating the charging of the first rechargeable storage device and the second rechargeable storage device by repeatedly performing sub-steps 1a) to 4a) discussed above, an initial step of precharging the second rechargeable storage device 60 to a predefined charge level is performed. Precharging the second rechargeable storage device includes the steps of: i) coupling the second power output path 32b between the voltage converter system 20 and the second rechargeable storage device 60 to transfer the output power from the voltage converter system to the second rechargeable storage device 60, and ii) operating the voltage converter system 20 to charge the second rechargeable storage device 60 with energy from the energy harvester 70 until the parameter V Batt2 The predefined threshold V has been reached Batt2-PC , where V Batt2-PC ≥V Batt2-low In this way, it is ensured that when the first rechargeable storage device 50 is charged and the load is enabled, at least a minimum amount of energy has been stored in the second rechargeable storage device 60 to guarantee a given autonomy of the application load. For example, if the energy harvester will stop supplying energy shortly after the application load starts to operate, then V Batt1 drops to the critical threshold level V Batt1-SW When the current is less than 0.1 V, there is at least enough available energy in the second rechargeable storage device to be transferred to the first rechargeable storage device.

[0083] In an embodiment, the method of the present invention comprises: Batt1 Has dropped to the critical threshold V Batt1-SW The following is an additional step for the case where the second rechargeable storage device 60 is not charged and therefore no charge can be transferred from the second rechargeable storage device to the first rechargeable storage device. In this case, if the parameter V Batt1 Has dropped to the critical threshold V Batt1-SW Below and if the second rechargeable storage device 60 is not charged, the method includes the following steps: disconnecting the first power input path and coupling the third power input path between an auxiliary energy source such as a primary battery and the voltage converter system to transfer input power from the auxiliary energy source to the voltage converter system 20; and operating the voltage converter system 20 to charge the first rechargeable storage device 50 with energy from the primary battery or an alternative power source until the parameter V of the first storage device 50 is Batt1 The upper threshold V has been reached Batt1-up .

[0084] Examples of primary batteries are alkaline batteries or zinc-carbon batteries. Advantageously, since a voltage converter is used to transfer charge from the primary battery to the first rechargeable storage device, the voltage of the primary battery does not need to be the same as the maximum voltage of the first storage device. The primary battery may for example be a AAA battery with a typical voltage level of 1.5V, while the first rechargeable storage device may be a rechargeable lithium-ion battery that can be recharged to a typical voltage of 3.7V.

[0085] In an embodiment, the voltage converter system 20 includes one or more voltage converters. The voltage converter is, for example, a DC-DC buck / boost voltage converter configured to: in >V out When the voltage is lowered, it operates in buck mode and in <V out When it operates in boost mode, V in and V out are the input voltage and output voltage of the voltage converter respectively.

[0086] In an embodiment, the voltage converter system 20 includes a voltage converter configured to convert input power received via coupled power input paths 31a, 31b, 31c into output power output via coupled power output paths 32a, 32b, 32c, and wherein the voltage converter is one of the following: a boost voltage converter, a buck voltage converter, or a buck-boost voltage converter. In other words, in these embodiments, a single voltage converter charges the first storage device and the second storage device and also transfers energy from the second storage device to the first storage device under conditions as discussed above.

[0087] According to a second aspect of the present invention, there is provided an integrated circuit for energy harvesting and Figure 3 An example of a system 100 for energy harvesting comprising such an integrated circuit 1 is shown in . With such a system for energy harvesting comprising an integrated circuit according to the invention, the energy harvesting method discussed above comprising the steps of charging a first rechargeable storage device and a second rechargeable storage device and transferring charge from the second rechargeable storage device to the first rechargeable storage device can be applied in an automated and controlled manner.

[0088] An integrated circuit for energy harvesting according to the invention must be interpreted as a microchip comprising an integrated circuit and a plurality of input pins and output pins (also called terminals). The microchip may have, for example, 16 to 32 terminals. Typically, the microchip has a compact package resulting in a square or rectangular footprint with a side length between 1 mm and 5 mm.

[0089] like Figure 3As shown, the integrated circuit 1 for energy harvesting includes a first terminal 11 connectable to an energy harvester 70, a second terminal 12 connectable to a first rechargeable storage device 50, and a third terminal 13 connectable to a second rechargeable storage device 60. The integrated circuit further includes: a voltage converter system 20, the voltage converter system is suitable for converting input power into output power to charge at least two storage devices; a controller 40, the controller is used to control the voltage converter system 20; and a monitoring unit 45, the monitoring unit is coupled to the controller 40 and is configured to monitor the parameter V Batt1 and parameter V Batt2 Parameter V Batt1 and V Batt2 The charge levels of the first rechargeable storage device and the second rechargeable storage device when they are connected to the second terminal 12 and the third terminal 13, respectively, are indicated.

[0090] In an embodiment, the parameter V Batt1 and parameter V Batt2 and correspond to the voltages sensed at the second terminal 12 and the third terminal 13, respectively. In other embodiments, the parameter V Batt1 and V Batt2 The charge counters correspond to the charge amounts counted by the charge counters during the charging of the first rechargeable storage device and the second rechargeable storage device, respectively.

[0091] like Figure 3 As shown, the integrated circuit 1 includes: a plurality of power input paths 31a, 31b, which are used to transfer input power from an energy source to a voltage converter system; and a plurality of power output paths 32a, 32b, which are used to transfer output power from the voltage converter system to the output terminals of the integrated circuit. These input power paths and output power paths must be interpreted as electrical conductors. However, the voltage converter system uses only one power path to receive input power and only one output path to output power when running. Therefore, the voltage converter system 20 includes an input selection circuit 31, which is used to select a power input path from a plurality of power input paths to receive input power via the selected power input path. The voltage converter further includes an output selection circuit 32, which is used to select a power output path from a plurality of power output paths to output output power via the selected output path.

[0092] The integrated circuit 1 includes at least: a first power input path 31a configured to transfer input power from the first terminal 11 to the voltage converter system 20; and a second power input path 31b for transferring input power from the third terminal 13 to the voltage converter system 20. The integrated circuit further includes at least: a first power output path 32a for transferring output power from the voltage converter system 20 to the second terminal 12; and a second power output path 32b for transferring output power from the voltage converter system to the third terminal 13. In this way, the voltage converter system can transfer charge from the second rechargeable storage device to the first rechargeable storage device when the second storage device is connected to the third terminal and, for example, the energy harvester is not operating.

[0093] The controller 40 is configured to be based on the parameter V Batt1 The comparison with the first predefined threshold value and / or the parameter V Batt2 The controller forms a plurality of specific combinations of power input paths and power output paths and switches between the plurality of specific combinations based on a comparison with a second predefined threshold. The specific combinations that the controller can form are as follows: i) a first combination formed by selecting the first power input path 31a and selecting the first power output path 32a; ii) a second combination formed by selecting the first power input path 31a and selecting the second power output path 32b; and iii) a third combination formed by selecting the second power input path 31b and selecting the first power output path 32a. As will be discussed in further detail below, the controller can not only form one of the three specific input / output combinations, but can also select a specific combination based on the parameter V Batt1 and / or parameter V Batt2 The comparison with the predefined thresholds switches from one specific combination to another specific combination. The first predefined threshold includes, for example, a threshold V Batt1-SW 、V Batt1-low and V Batt1-up , and the second predefined threshold includes, for example, the threshold V discussed above Batt2-max and V Batt2-low .

[0094] The first and second combinations of selected power input / output paths as defined above correspond to combinations in which the voltage converter system transfers power from the energy harvester to the first storage device and the second storage device, respectively. The third combination corresponds to the voltage converter system transferring power from the second storage device to the first storage device. Batt1 The upper and lower threshold levels can be configured by Batt1 and / or V Batt2The energy harvesting method according to the present invention is implemented by switching between a first combination and a second combination of power input / output paths. In fact, the energy harvesting method discussed above includes switching between a first combination and a second combination of power input / output paths so that V Batt1 Keep at the threshold V Batt1-low With V Batt1-up The method according to the present invention discussed above also includes the step of switching to a third combination of power input / output paths, wherein if V Batt1 drops to the critical threshold V Batt1-SW The condition of switching to the third combination of power input / output paths is performed only when the second storage device is charged, as discussed above, by increasing V Batt2 Determined by comparing with a threshold.

[0095] The controller is based on the conditions and parameters V discussed above. Batt1 and V Batt2 In other words, the controller is configured to: Batt1 becomes equal to or greater than the upper threshold V Batt1-up When and at parameter V Batt2 Below the upper threshold V Batt2-max When the parameter V Batt1 From the upper threshold V Batt1-up Falls to the lower threshold V Batt1-low When V Batt1-low <V Batt1-up , switch from the second combination to the first combination; in parameter V Batt1 From the lower threshold V Batt1-low drops to the critical threshold V Batt1-SW When V Batt1-SW <V Batt1-low , and at V Batt2 Above the lower threshold V Batt2-low When V Batt2-low <V Batt2-max , switch from the first combination to the third combination.

[0096] In an embodiment, the monitoring unit 45 comprises a device for transmitting the parameter V Batt1 and V Batt2 A signal comparator that compares with a predefined threshold. As mentioned above, the parameter V Batt1 and V Batt2The signal comparator may correspond to the detection of a voltage generated by a voltage measurement, a charge amount generated by a charge counter, or any other quantity representing the state of charge of the rechargeable energy storage device. The signal comparator may be an analog signal comparator or a digital signal comparator as known in the art. For an embodiment using a digital signal comparator, an ADC (analog-to-digital converter) is first used to convert the general analog signal V Batt1 and V Batt2 The predefined threshold may be a value stored locally in the controller, or the predefined threshold may be generated by a reference voltage generator, or a voltage configurator external to the PMIC may be used and the threshold may be transmitted through a configuration terminal or connector.

[0097] The voltage converter system 20 includes one or more voltage converters, and the voltage converter is, for example, a boost voltage converter, a buck voltage converter, or a buck-boost voltage converter. Figure 4a and Figure 5 , an example of an embodiment of a voltage converter system 20 is shown that includes a single voltage converter for converting input power received via a selected power input path into output power output via a selected power output path. Figure 4b , Figure 6a and Figure 6b In FIG. 1 , an example of a voltage converter system 20 including two voltage converters is shown, and in FIG. Figure 7 and Figure 8 , an example of a voltage converter system including three voltage converters is shown. These various embodiments of the voltage converter system 20 will be further discussed in more detail below.

[0098] Use of the term "controller" must be interpreted in the broadest sense as electronic digital circuits typically including combinatorial logic.A controller controlling a voltage converter system is configured to control, for example, switching of one or more voltage converters and to control switching of input selection circuits and output selection circuits.

[0099] Figure 4a and Figure 5 An embodiment of a voltage converter system including a single voltage converter is schematically illustrated for converting input power received via a selected power input path into output power output via a selected power output path. The single voltage converter shown uses an inductor 25, which is typically located external to the integrated circuit and can be coupled to the integrated circuit via, for example, two dedicated terminals 14, 15 or by any other suitable coupling means. The operation of the voltage converter and the selection of the input path and the output path will be discussed further.

[0100] exist Figure 4aIn the illustrated embodiment, the input selection circuit 31 includes: a first input switch SW1-IN for enabling and disabling the flow of current in the first power input path 31a; a second input switch SW2-IN for enabling and disabling the flow of current in the second power input path 31b; a first output switch SW1-OUT for enabling and disabling the flow of current in the first power output path 32a; and a second output switch SW2-OUT for enabling and disabling the flow of current in the second power output path 32b.

[0101] It should be noted that when a specific input power path is selected, by definition, this means that the other remaining input paths are deselected. Therefore, selecting "one (a)" power input path from multiple power input paths to receive input power via the selected power input path must be interpreted as selecting "one" power input path from multiple power input paths. This is because the voltage converter system can only receive one power supply as an input channel, and therefore only one power input path is selected at a time. The same is true for the power output path, since only one output path can be selected at a time, if a specific output path is selected, by definition, this means deselecting the other remaining output paths. Therefore, selecting "one (a)" power output path from multiple power output paths to output output power via the selected power output path must be interpreted as selecting "one" power output path from multiple power output paths. On the other hand, for example, all power input paths can be deselected and / or all power output paths can be deselected to stop power transfer.

[0102] In order to charge the first rechargeable storage device 50 with energy from the energy harvester 70, the first input path 31a and the first output path 32a will be selected, and thus the other input paths and output paths will be deselected and remain deselected during the charging of the first storage device 50. For example, the second input path 31b and the second output path 32b are deselected by opening the switches SW2-IN and SW2-OUT, respectively. These switches are as follows: Figure 4a shown.

[0103] In order to charge the second rechargeable storage device 60 with energy from the energy harvester, the first input path 31a and the second output path 32b will be selected, and the other input paths and output paths will be deselected and remain deselected during the charging of the second rechargeable storage device. For example, the second input path 31b and the first output path 32a are deselected by opening the switches SW2-IN and SW1-OUT, respectively.

[0104] In order to charge the first rechargeable storage device 50 with energy from the second rechargeable storage device 60, the second input path 31b and the first output path 32a will be selected, and the other input paths and output paths will be deselected and remain deselected during the charge transfer from the second rechargeable storage device to the first rechargeable storage device. For example, the first input path 31a and the second output path 32b are deselected by opening the switches SW1-IN and SW2-OUT, respectively.

[0105] In a preferred embodiment, the voltage converter 20 is as follows Figure 4a A DC-DC buck / boost voltage converter capable of operating in a boost mode or a buck mode is shown. When the voltage converter input voltage is less than the voltage converter output voltage, the buck / boost voltage converter will operate in the boost mode. On the other hand, if the input voltage is higher than the output voltage, the buck / boost voltage converter will operate in the buck mode. For example, when the first input path 31a and the first output path 32a are selected, the input voltage and the output voltage for determining the operating mode correspond to the voltage at the first terminal 11 and the voltage at the second terminal 12, respectively.

[0106] To operate in boost mode Figure 4a The buck / boost voltage converter shown in charges the first storage device with energy from the energy harvester, with switch SW1-IN maintained closed and switch 27a maintained open during the charging of the first storage device. The boost mode begins with a magnetic energy charging phase of the inductor 25, in which switch 27b is closed and switch SW1-OUT is open, followed by a magnetic energy discharging phase, in which switch 27b is open and switch SW1-OUT is closed. As is known in the art, by repeatedly controlling switches 27b and SW1-OUT, power is transferred from the first terminal 11 (i.e., the terminal to which the energy harvester is connected) to the second terminal 12 (the terminal to which the first rechargeable storage device is connected) in a boost mode.

[0107] To operate in buck mode Figure 4a The buck / boost voltage converter shown in charges the first storage device, with switch SW1-OUT maintained closed and switch 27b maintained open during the charging of the first storage device. The buck mode begins with a magnetic energy charging phase of the inductor 25, in which switch 27a is open and switch SW1-IN is closed, followed by a magnetic energy discharging phase, in which switch 27a is closed and switch SW1-IN is open. As is known in the art, by repeatedly controlling switches 27a and SW1-IN, power is transferred from the first terminal 11 (i.e., the terminal to which the energy harvester is connected) to the second terminal 12 (the terminal to which the first rechargeable storage device is connected) in buck mode.

[0108] When the first storage device 50 is charged, that is, reaches the parameter value V Batt1-up , the second storage device 60 connected to the third terminal 13 of the integrated circuit can start to charge with energy from the energy harvester. Therefore, the first output path 32a is deselected by opening the switch SW1-OUT and by maintaining this switch open during the charging of the second rechargeable storage device.

[0109] To charge the second rechargeable storage device with energy from the energy harvester, the voltage converter will also operate in buck mode or boost mode, depending on the input voltage and output voltage of the voltage converter. To operate in boost mode, switch SW1-IN remains closed and switch 27a remains open. Similar to as discussed above, boost mode begins with a magnetic energy charging phase of the inductor, where switch 27b is closed and switch SW2-OUT is open, followed by a magnetic energy discharging phase, where switch 27b is open and switch SW2-OUT is closed. This cycle of magnetically charging and magnetically discharging the inductor is cyclically repeated.

[0110] To charge the second rechargeable storage device in buck mode with energy from the energy harvester, switch SW2-OUT remains closed and switch 27b remains open. Buck mode begins with a charging phase of inductor 25, in which switch 27a is open and switch SW1-IN is closed, followed by a discharging phase, in which switch 27a is closed and switch SW1-IN is open. This cycle of magnetically charging and magnetically discharging the inductor is cyclically repeated.

[0111] Figure 4a The various switches shown in the drawings, i.e. switches with reference numerals 27a, 27b, SW1-IN, SW2-IN, SW1-OUT and SW2-OUT, must be interpreted as electronic switches configured to open or close conductive paths or conductors. These switches are, for example, analog electronic switches known in the art. These switches use, for example, MOS transistors. For Figure 4a In the exemplary embodiment shown, the number of electronic switches of the integrated circuit is limited because some of these switches are used not only as standard switches required to operate the DC / DC voltage converter, but also as switches forming the input path selection circuit and the output path selection circuit.

[0112] As discussed above, the energy converter system 20 is not limited to a particular number of voltage converters. Figure 4b, an example of a voltage converter system 20 is shown, the voltage converter system includes two buck / boost voltage converters, and wherein the voltage converter system includes a plurality of switches, referenced as 27a, 27b, 28a, 28b, SW1-IN, SW2-IN, SW1-OUT, and SW2-OUT. The switches 27a, 27b, SW1-IN, SW1-OUT, and SW2-OUT are used to operate the first buck / boost voltage converter to transfer power from the energy harvester to the voltage V Batt1 The first rechargeable storage device or voltage is V Batt2 The switches 28a, 28b, SW2-IN and SW1-OUT are used to operate the second buck / boost voltage converter to convert power from the voltage V Batt2 The second rechargeable storage device delivers a voltage of V Batt1 It should be noted that the switches SW1-IN, SW2-IN, SW1-OUT and SW2-OUT are not only used for the nominal operation of the buck / boost voltage converter, but these switches also form part of the input selection circuit 31 and the output selection circuit 32 for selecting the output voltage of the first rechargeable storage device. Figure 4b Input power paths and output power paths are schematically shown. In this example, each buck / boost voltage converter uses a dedicated inductor 25, 26.

[0113] In some embodiments, in addition to the nominal power switches used to operate one or more voltage converters of the voltage converter system 20, additional specialized switches are used to form input selection circuits and / or output selection circuits. Figures 6a to 8 As shown, multiple embodiments will be further discussed.

[0114] exist Figure 6a , an example of an embodiment of a voltage converter system 20 is shown, which includes two voltage converters 21a and 21b in addition to an input selection circuit 31 and an output selection circuit 32. Figure 6a As further shown, two power input paths 31a and 31b and two power output paths 32a and 32b are shown in this example. The first voltage converter 21a is used to convert the input power received via the first power input path 31a into output power output via the first power output path 32a or the second power output path 32b according to the power output path selected by the output selection circuit 32. The second voltage converter 21b is used to convert the input power received via the second power input path 31b into output power output via the first power output path 32a. The two voltage converters can use one or two inductors ( Figure 6aThe two voltage converters 21a, 21b do not necessarily have to be of the same type, for example, the first voltage converter 21a may be a buck-boost voltage converter and the second voltage converter 21b may be a buck voltage converter or a boost voltage converter.

[0115] exist Figure 6b In the figure, it is shown that the Figure 6a An alternative embodiment of the same functionality as the embodiment shown, but in which the output selection circuit 32 uses three switches SW1-OUT, SW2-OUT and SW3-OUT instead of two output switches.

[0116] exist Figure 7 , an example of an embodiment of a voltage converter system 20 including three voltage converters 21a, 21b, 21c is shown. The first voltage converter 21a converts input power received via a first power input path 31a into output power output via a first power output path 32a. The second voltage converter 21b converts input power received via a second power input path 31b into output power output via the first power output path 32a. Finally, the third voltage converter 21c converts input power received via the first power input path 31a into output power output via the second power output path 32b. The three voltage converters may use one, two, or three inductors ( Figure 7 not shown).

[0117] exist Figure 8 , an example is shown in which the input selection circuit 31 can select from three power input paths 31a, 31b and 31c. The voltage converter system 20 shown includes three voltage converters 21a, 21b and 21d. The functionality of the first voltage converter 21a and the second voltage converter 21b in this example is the same as Figure 6a The example shown is the same as discussed above. The third voltage converter 21d is used to convert input power received via the third power input path 31c into output power output via the first power output path 32a.

[0118] For the integrated circuit for energy harvesting according to the present invention, those skilled in the art may specify the integrated circuit for energy harvesting according to the present invention in addition to the above description and Figures 4a to 8Other embodiments of the voltage converter system 20 other than the voltage converter system shown. The common point of the embodiments of the voltage converter system according to the present invention is that these voltage converter systems all include: an input selection circuit 31, which is used to select a power input path from a plurality of power input paths to receive input power via the selected power input path; and an output selection circuit 32, which is used to select a power output path from a plurality of power output paths to output output power via the selected power output path. It should be noted that, as discussed above, in some embodiments, the switches used to select the power input path or select the power output path correspond to the power switches of the DC / DC voltage converter, which are used for the nominal operation of the DC / DC voltage converter. In this way, the total number of switches required for the voltage converter system can be limited.

[0119] In an embodiment according to the present invention, the controller 40 is configured to perform step A) selecting the first input path 31a and performing the following sub-steps A1) to A4): A1) selecting the first output path 32a, A2) operating the voltage converter 20 to convert the input power received via the first power input path 31a into the output power outputted via the first power output path, A3) if V Batt1 becomes equal to or greater than the upper threshold V Batt1-up , then the first output path 32a is deselected, and A4) if V Batt2 Below the upper threshold V Batt2-max ,but

[0120] i) selecting the second output path 32b,

[0121] ii) operating the voltage converter system 20 to convert input power received via the first power input path 31a into output power output via the second power output path 32b, and

[0122] iii) If V Batt1 Then from the upper threshold V Batt1-up Falls to the lower threshold V Batt1-low , where V Batt1-low <V Batt1-up , then the second output path 32b is deselected and sub-step A1) is restarted.

[0123] In this way, by executing step A) and its sub-steps A1) to A4) outlined above, the controller 40 sets the parameter V Batt1 Maintain at the threshold V Batt1-low With V Batt1-up between.

[0124] In an embodiment, if V Batt1 From the lower threshold VBatt1-low drops to the critical threshold V Batt1-SW , where V Batt1-SW <V Batt1-low , and if V Batt2 Above the lower threshold V Batt2-low , where V Batt2-low <V Batt2-max , the controller 40 is further configured to perform step B). Step B) consists of the following sub-steps: B1) selecting the second input path 31b, B2) selecting the first output path 32a, and B3) operating the voltage converter 20 to convert the input power received via the second power input path 31b into output power output via the first power output path 32a.

[0125] In this way, by transferring charge from the second rechargeable storage device to the first rechargeable storage device, the controller prevents the first rechargeable storage device from being completely discharged when the energy harvester is not operating. At the same time, the application load coupled to the first rechargeable storage device can continue to operate even if the energy harvester has stopped operating.

[0126] In an embodiment according to the present invention, when performing sub-step A4) discussed above, if V Batt2 The upper threshold V has been reached Batt2-max , the controller is configured to additionally perform step iv). The additional step iv) comprises performing one of the following steps: i) deselecting the second power output path 32b and / or deselecting the first power input path 31a, ii) stopping operation of the voltage converter system 20, iii) selecting the first input path 31a and selecting the first output path 32a.

[0127] In this way, by performing this additional step A4) iv), charge is no longer transferred to the second rechargeable storage device connected to the third terminal of the integrated circuit. This avoids the second rechargeable storage device from being overcharged.

[0128] In an embodiment, when option iii) of selecting the first input path 31a and selecting the first output path 32a is applied in step A4) iv), the energy harvester again continues to charge the first rechargeable storage device with energy from the energy harvester. Batt1-up is not the maximum charge level of the first rechargeable storage device, and if the maximum charge level V Batt1-max Exists and V Batt1-max >V Batt1-up , then when the second rechargeable storage device is fully charged, the first rechargeable storage device can continue to charge to the maximum charge level V Batt1-max .

[0129] In an embodiment, when executing the above step B, the controller is configured to additionally execute sub-step B4), that is, if the voltage V Batt1 becomes equal to or greater than the upper threshold V Batt1-up , at least one of the following steps is performed: i) deselecting the first power output path 32a and / or deselecting the second power input path 31b, ii) selecting the first input path 31a and selecting the second output path 32b, iii) stopping the operation of the voltage converter 20. In an embodiment, when step ii) is applied, the energy harvester will continue to charge the second rechargeable storage device when in operation.

[0130] In this way, by performing the additional sub-step B4, charge is no longer transferred from the second rechargeable storage device connected to the third terminal to the first rechargeable storage device connected to the second terminal. This prevents the first rechargeable storage device from being overcharged. When the first rechargeable storage device is charged to the upper limit threshold V using the charge from the second rechargeable storage device, the charge from the second rechargeable storage device is transferred to the first rechargeable storage device connected to the second terminal. Batt1-up After that, if the application load is consuming power, V Batt1 The value of will start to decrease again. If the energy harvester still does not operate or still cannot provide sufficient power, even after the first power input path and the first power output path are selected, the parameter V Batt1 will continue to drop and drop again to V Batt1-SW Below. When V Batt1 Down to V Batt1-SW When V Batt1 Down to V Batt1-low When power is transferred from the energy harvester to the first rechargeable storage device, and V Batt1 Increase again until V Batt1 Reaching the upper threshold V Batt1-up .

[0131] In an embodiment, the monitoring unit 45 is configured to monitor the parameter V H , which parameter indicates whether the energy harvester connected to the first terminal is in operation. In an embodiment, the parameter may be a voltage measured at the first input terminal. Based on the parameter V H , the controller can decide when to reselect the first power input path to receive power from the energy harvester and charge the first rechargeable storage device with charge from the energy harvester instead of charging the first rechargeable storage device with charge from the second rechargeable storage device.

[0132] The integrated circuit 1 for energy harvesting according to the present invention is not limited to the number of power input paths and the number of power output paths. Figure 5 , an integrated circuit 1 having a voltage converter is shown, the integrated circuit having an input selection circuit 31 configured to select between three power input paths 31a, 31b and 31c, and having an output selection circuit 32 configured to select between three power output paths 32a, 32b and 32c. In this example, the input selection circuit 31 and the output selection circuit 32 have an additional switch SW3-IN and an additional switch SW3-OUT, respectively.

[0133] In other embodiments, the third power input path 31c is used to transfer input power from the fourth terminal to the voltage converter system 20. The fourth terminal can be connected to an auxiliary energy source such as a primary battery. In these embodiments, if the parameter V Batt1 From the lower threshold V Batt1-low drops to the critical threshold V Batt1-SW , and if V Batt2 Below the lower threshold V Batt2-low , the controller 40 is configured to perform the following steps: C1) select the third power input path 31c, C2) select the first power output path 32a, and C3) operate the voltage converter 20 to convert the input power received via the third power input path 31c into output power output via the first power output path 32a.

[0134] In this way, if, for example, the energy harvester is not operating, and if the second rechargeable storage device is not being charged, the first rechargeable storage device may be charged using the auxiliary power source coupled to the fourth terminal.

[0135] In certain embodiments, the third power output path 32c couples the voltage converter system to a fifth terminal, which can be connected to a voltage V AUX In this way, when the first rechargeable storage device and the second rechargeable storage device are fully charged, the third rechargeable storage device can be charged.

Claims

1. A method for energy harvesting using a voltage converter system (20) for converting input power into output power and for charging at least a first rechargeable storage device (50) and a second rechargeable storage device (60), the method comprising the following steps: coupling a first power input path (31a) between an energy harvester (70) and the voltage converter system (20) to transfer input power from the energy harvester (70) to the voltage converter system, Monitoring parameters V respectively indicative of the charge levels of the first rechargeable storage device (50) and the second rechargeable storage device (60) Batt1 and parameter V Batt2 , coupling the first rechargeable storage device (50) to an application load (90) such that the first rechargeable storage device is capable of supplying power to the application load (90) when being charged, Coordinating the charging of the first rechargeable storage device (50) and the second rechargeable storage device (60) by repeatedly performing the following sub-steps: 1a) coupling a first power output path (32a) between the voltage converter system (20) and the first rechargeable storage device (50) to transfer output power from the voltage converter system to the first rechargeable storage device (50), 2a) operating the voltage converter system (20) to transfer charge from the energy harvester (70) to the first rechargeable storage device (50) so as to charge the first rechargeable storage device (50) with energy from the energy harvester (70), and operating the voltage converter system to charge the first rechargeable storage device until the parameter V Batt1 The upper threshold V has been reached Batt1-up , 3a) If V Batt1 The upper threshold V has been reached Batt1-up , and if V Batt2 Below the upper threshold V Batt2-max ,but i) decoupling the first power output path (32a) and coupling a second power output path (32b) between the voltage converter system (20) and the second rechargeable storage device (60) to transfer output power from the voltage converter system to the second rechargeable storage device (60), and ii) operating the voltage converter system (20) to transfer charge from the energy harvester (70) to the second rechargeable storage device (60) so as to charge the second rechargeable storage device (60) with energy from the energy harvester (70), 4a) If during charging of the second rechargeable storage device (60) the parameter V Batt1 Then from the upper threshold V Batt1-up Falls to the lower threshold V Batt1-low , where V Batt1-low <V Batt1-up , then disconnect the second power output path (32b) and restart step 1a), If i) the parameter V of the first rechargeable storage device (50) Batt1 has dropped to the critical threshold V Batt1-SW Below, where V Batt1-SW <V Batt1-low , and if ii) the parameter V Batt2 Equal to or above a predefined threshold V Batt2-low , then transferring energy from the second rechargeable storage device (60) to the first rechargeable storage device (50), the transferring energy from the second rechargeable storage device (60) to the first rechargeable storage device (50) comprising the following sub-steps: 1b) disconnecting the first power input path (31a), 2b) coupling a second power input path (31b) between the second rechargeable storage device (60) and the voltage converter system (20) to transfer input power from the second rechargeable storage device (60) to the voltage converter system (20), and 3b) operating the voltage converter system (20) to charge the first rechargeable storage device (50) with energy from the second rechargeable storage device (60) until the parameter V of the first rechargeable storage device (50) is Batt1 Reaching the upper threshold V Batt1-up .

2. The method according to claim 1, wherein: The energy storage capacity of the second rechargeable storage device (60) is more than five times greater than the energy storage capacity of the first rechargeable storage device (50).

3. The method according to claim 1 or 2, wherein: The step of coordinating the charging of the first rechargeable storage device (50) and the second rechargeable storage device (60) comprises the following sub-steps: 3a)iii) If V Batt2 The upper threshold V has been reached Batt2-max , perform at least one of the following steps: a) disconnecting the second power output path (32b) and / or disconnecting the first power input path (31a), b) ceasing to operate said voltage converter system (20), c) coupling the first power input path (31a) and coupling the first power output path (32b).

4. The method according to claim 1 or 2, wherein: The transferring of energy from the second rechargeable storage device (60) to the first rechargeable storage device (50) comprises the further sub-steps of: 4b) If the parameter V Batt1 The upper threshold V has been reached Batt1-up , perform one or a combination of the following steps: i) disconnecting the first power output path (32a) and / or disconnecting the second power input path (31b), ii) coupling the first power input path (31a) and coupling the second power output path (32b), iii) stopping the operation of the voltage converter system (20).

5. The method according to claim 1 or 2, comprising the following steps: If the parameter V Batt1 has dropped to the critical threshold V Batt1-SW and if the second rechargeable storage device (60) is not charged, the first power input path (31a) is disconnected and a third power input path (31c) is coupled between an auxiliary energy source and the voltage converter system to transfer input power from the auxiliary energy source to the voltage converter system (20), and the voltage converter system (20) is operated to charge the first rechargeable storage device (50) with energy from the auxiliary energy source until the parameter V of the first rechargeable storage device (50) is less than or equal to 0. Batt1 The upper threshold V has been reached Batt1-up .

6. The method according to claim 1 or 2, comprising the following steps: pre-charging the second rechargeable storage device (60) by performing the following steps: i) coupling the second power output path (32b) between the voltage converter system (20) and the second rechargeable storage device (60) to transfer output power from the voltage converter system to the second rechargeable storage device (60), ii) operating the voltage converter system (20) to charge the second rechargeable storage device (60) with energy from the energy harvester (70) until the parameter V Batt2 The predefined threshold V has been reached Batt2-PC , where V Batt2-PC ≥V Batt2-low , and wherein the pre-charging step is performed before performing the coordinating charging of the first rechargeable storage device (50) and the second rechargeable storage device (60).

7. The method according to claim 1 or 2, wherein: The voltage converter system (20) includes a voltage converter configured to convert input power received via a coupled power input path (31a, 31b, 31c) into output power output via a coupled power output path (32a, 32b, 32c), and wherein the voltage converter is one of the following: a boost voltage converter, a buck voltage converter, or a buck-boost voltage converter.

8. The method according to claim 2, wherein: The energy storage capacity of the second rechargeable storage device (60) is more than ten times greater than the energy storage capacity of the first rechargeable storage device (50).

9. The method according to claim 5, wherein: The auxiliary energy source is a primary battery.

10. An integrated circuit (1) for energy harvesting, the integrated circuit comprising a voltage converter system (20) adapted to convert input power into output power and adapted to charge at least two rechargeable storage devices, a first terminal (11), which can be connected to an energy harvester (70), a second terminal (12) which is connectable to a first rechargeable storage device (50), a third terminal (13) which can be connected to a second rechargeable storage device (60), a controller (40) for controlling the voltage converter system (20), a plurality of power input paths, the plurality of power input paths comprising at least a first power input path (31a) for transferring input power from the first terminal (11) to the voltage converter system (20), a plurality of power output paths, the plurality of power output paths comprising at least a first power output path (32a) for delivering output power from the voltage converter system (20) to the second terminal (12) and a second power output path (32b) for delivering output power from the voltage converter system to the third terminal (13), a monitoring unit (45) coupled to the controller (40) and configured to monitor a parameter V indicating a charge level of the first rechargeable storage device (50) and the second rechargeable storage device (60) when the first rechargeable storage device (50) and the second rechargeable storage device (60) are connected to the second terminal (12) and the third terminal (13), respectively; Batt1 and parameter V Batt2 , It is characterized in that The plurality of power input paths include a second power input path (31b) for transmitting input power from the third terminal (13) to the voltage converter system (20), and characterized in that the voltage converter system (20) comprises an input selection circuit (31) and an output selection circuit (32), wherein the input selection circuit is configured to select a power input path from the plurality of power input paths to receive input power via the selected power input path, and the output selection circuit is configured to select a power output path from the plurality of power output paths to output output power via the selected power output path, And it is characterized in that the controller (40) is configured to be based on the parameter V Batt1 The comparison with the first predefined threshold value and / or the parameter V Batt2 The method forms a plurality of specific combinations of the power input path and the power output path based on a comparison with a second predefined threshold and switches between the plurality of specific combinations, and wherein the specific combinations include: i) a first combination formed by selecting the first power input path (31a) and selecting the first power output path (32a), ii) a second combination formed by selecting the first power input path (31a) and selecting the second power output path (32b), iii) a third combination formed by selecting the second power input path (31b) and selecting the first power output path (32a).

11. The integrated circuit (1) according to claim 10, wherein: The controller (40) is configured to perform the following operations: A. Select the first power input path (31a) and repeat the following sub-steps: A1) selecting the first power output path (32a), A2) operating the voltage converter system (20) to convert input power received via the first power input path (31a) into output power output via the first power output path (32a), A3) If V Batt1 becomes equal to or greater than the upper threshold V Batt1-up , then the first power output path (32a) is deselected, A4) If V Batt2 Below the upper threshold V Batt2-max ,but i) selecting the second power output path (32b), ii) operating the voltage converter system (20) to convert input power received via the first power input path (31a) into output power output via the second power output path (32b), and iii) If V Batt1 Then from the upper threshold V Batt1-up Falls to the lower threshold V Batt1-low , where V Batt1-low <V Batt1-up , then cancel the selection of the second power output path (32b) and restart step A1), B. If V Batt1 has been reduced from the lower threshold V Batt1-low drops to the critical threshold V Batt1-SW , where V Batt1-SW <V Batt1-low , and if V Batt2 Above the lower threshold V Batt2-low , where V Batt2-low <V Batt2-max , then perform the following sub-steps: B1) selecting the second power input path (31b), B2) selecting the first power output path (32a), and B3) operating the voltage converter system (20) to convert input power received via the second power input path (31b) into output power output via the first power output path (32a).

12. The integrated circuit (1) according to claim 11, wherein: Said sub-step A4) comprises the further steps of: A4)iv) If V Batt2 The upper threshold V has been reached Batt2-max , at least one of the following steps is performed: i) deselecting the second power output path (32b) and / or deselecting the first power input path (31a), ii) stopping operation of the voltage converter system (20), iii) selecting the first power input path (31a) and selecting the first power output path (32a).

13. An integrated circuit (1) according to claim 11 or claim 12, wherein: The controller is configured to perform the further sub-steps of: B4) If the voltage V Batt1 becomes equal to or greater than the upper threshold value V Batt1-up , at least one of the following steps is performed: i) deselecting the first power output path (32a) and / or deselecting the second power input path (31b), ii) selecting the first power input path (31a) and selecting the second power output path (32b), iii) stopping the operation of the voltage converter system (20).

14. The integrated circuit (1) according to claim 10, wherein: The controller (40) is further configured to: If the parameter V Batt1 becomes equal to or greater than the upper threshold V Batt1-up And if the parameter V Batt2 Below the upper threshold V Batt2-max , then switch from the first combination to the second combination, If the parameter V Batt1 has been increased from the upper threshold V Batt1-up Falls to the lower threshold V Batt1-low , where V Batt1-low <V Batt1-up , then switch from the second combination to the first combination, and If the parameter V Batt1 has been reduced from the lower threshold V Batt1-low drops to the critical threshold V Batt1-SW , where V Batt1-SW <V Batt1-low , and if V Batt2 Above the lower threshold V Batt2-low , where V Batt2-low <V Batt2-max , then switch from the first combination to the third combination.

15. The integrated circuit (1) according to any one of claims 10 to 12 and 14, wherein: The input selection circuit (31) includes a first input switch (SW1-IN) for enabling and disabling the flow of current in the first power input path (31a), a second input switch (SW2-IN) for enabling and disabling the flow of current in the second power input path (31b), a first output switch (SW1-OUT) for enabling and disabling the flow of current in the first power output path (32a), and a second output switch (SW2-OUT) for enabling and disabling the flow of current in the second power output path (32b).

16. The integrated circuit (1) according to any one of claims 10 to 12 and 14, comprising a fourth terminal, which can be connected to an auxiliary energy source, and wherein: The plurality of power input paths include a third power input path (31c) for delivering input power from the fourth terminal to the voltage converter system, and wherein the specific combination includes: iv) a fourth combination formed by selecting the third power input path (31c) and selecting the first power output path (32a).

17. The integrated circuit (1) according to any one of claims 10 to 12 and 14, wherein: The voltage converter system (20) includes a voltage converter for converting input power received via a selected power input path (31a, 31b, 31c) into output power output via a selected power output path (32a, 32b, 32c), and wherein the voltage converter is one of the following: a boost voltage converter, a buck voltage converter, or a buck-boost voltage converter.

18. The integrated circuit (1) according to any one of claims 10 to 12 and 14, wherein: The voltage converter system (20) comprises a first voltage converter (21a) for converting input power received via the first power input path (31a) into output power output via the first power output path (32a) or the second power output path (32b), A second voltage converter (21b) for converting input power received via the second power input path (31b) into output power output via the first power output path (32a).

19. The integrated circuit (1) according to any one of claims 10 to 12 and 14, wherein: The voltage converter system (20) comprises a first voltage converter (21a) for converting input power received via the first power input path (31a) into output power output via the first power output path (32a), a second voltage converter (21b) for converting input power received via the second power input path (31b) into output power output via the first power output path (32a), A third voltage converter (21c) for converting input power received via the first power input path (31a) into output power output via the second power output path (32b).

20. The integrated circuit (1) according to claim 16, wherein The auxiliary energy source is a primary battery.

21. A system for energy harvesting, the system comprising: · An integrated circuit (1) according to any one of claims 10 to 20, an energy harvester (70), the energy harvester being coupled to the first terminal (11), a first rechargeable storage device (50) coupled to the second terminal (12), a second rechargeable storage device (60) coupled to the third terminal (13), wherein the energy storage capacity of the second rechargeable storage device (60) is more than five times greater than the energy storage capacity of the first rechargeable storage device (50).

22. The system of claim 21, wherein: The first rechargeable storage device is a rechargeable battery, a capacitor or a supercapacitor.

23. The system of claim 21, wherein: The second rechargeable storage device is a rechargeable battery, a capacitor or a supercapacitor.

24. The system of claim 21, wherein: The energy storage capacity of the second rechargeable storage device (60) is more than ten times greater than the energy storage capacity of the first rechargeable storage device (50).

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