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JP-2026076045-A - Initial charging circuit, power supply device, and energy harvesting device

JP2026076045AJP 2026076045 AJP2026076045 AJP 2026076045AJP-2026076045-A

Abstract

[Problem] To quickly supply voltage to the system without generating voltage ripple by repeatedly switching the switch on and off, and to charge the energy storage device with the excess power. [Solution] An initial charging circuit is provided that controls the current flowing between a first energy storage element, which stores energy from an energy harvesting power source, and a second energy storage element, which has a larger capacity than the first energy storage element and stores energy from the first energy storage element, wherein the initial charging circuit comprises a resistor with one end connected to the first energy storage element, a first transistor with one end connected to the other end of the resistor and the other end connected to the second energy storage element, and an operational amplifier that changes the amount of current flowing between the first energy storage element and the second energy storage element when the first transistor is ON, based on the difference between the voltage at one end of the first transistor and a reference voltage. [Selection Diagram] Figure 2

Inventors

  • 多賀 史朗

Assignees

  • 旭化成エレクトロニクス株式会社

Dates

Publication Date
20260511
Application Date
20241023

Claims (16)

  1. An initial charging circuit that controls the current flowing between a first energy storage element, which stores energy from an energy harvesting power source, and a second energy storage element, which has a larger capacity than the first energy storage element and stores energy from the first energy storage element, The initial charging circuit described above is A resistor with one end connected to the first energy storage element, A first transistor having one end connected to the other end of the resistor and the other end connected to the second energy storage element, An initial charging circuit having an operational amplifier that changes the amount of current flowing between the first energy storage element and the second energy storage element when the first transistor is in the ON state, based on the difference between the voltage at one end of the first transistor and a reference voltage.
  2. The first transistor is a first-conductivity type MOSFET, The resistive portion includes a second transistor which is a first-conductivity type MOSFET. The initial charging circuit according to claim 1, wherein the operational amplifier changes the on-resistance of the second transistor when it is on based on the difference between the voltage at one end of the first transistor and the reference voltage.
  3. The initial charging circuit according to claim 2, wherein the absolute value of the threshold voltage of the second transistor is greater than the absolute value of the threshold voltage of the first transistor.
  4. The initial charging circuit has a third transistor, which is a first-conductivity type MOSFET, with one end connected to the first energy storage element and the other end connected to the second energy storage element, and connected in parallel with the first transistor and the resistor. The initial charging circuit according to claim 2, wherein the operational amplifier changes the amount of current flowing between the first energy storage element and the second energy storage element when the third transistor is in the ON state, based on the difference between the voltage at one end of the first transistor and the reference voltage.
  5. The initial charging circuit according to claim 2, wherein the resistor has a first resistor connected in series with the second transistor.
  6. The initial charging circuit according to claim 2, wherein the resistive section has a second resistor connected in parallel with the second transistor.
  7. An initial charging circuit according to any one of claims 1 to 6, The first energy storage element and, The system comprises the aforementioned second energy storage element, At least one of the first energy storage element or the second energy storage element is a power supply device that supplies power to an external system.
  8. The system includes a voltage monitoring unit that monitors the output voltage of the second energy storage element and outputs an output signal corresponding to the output voltage, The power supply device according to claim 7, which outputs a switching signal to switch the system to an operating mode with different power consumption in accordance with the output signal.
  9. The operational amplifier is equipped with a voltage monitoring unit that monitors the output voltage and outputs an output signal corresponding to the output voltage, The power supply device according to claim 7, which outputs a switching signal to switch the system to an operating mode with different power consumption according to the output voltage.
  10. The initial charging circuit according to claim 4, The first energy storage element and, The second energy storage element and, A voltage monitoring unit that monitors the output voltage of the second energy storage element, The system includes a control unit that controls the initial charging circuit, At least one of the first energy storage element or the second energy storage element supplies power to an external system. The control unit controls the third transistor of the initial charging circuit to turn on when the output voltage becomes greater than a predetermined value.
  11. The initial charging circuit comprises a fourth transistor, one end of which is connected to the output of the operational amplifier and the other end of which is connected to ground. The power supply device according to claim 10, wherein the control unit controls the third transistor to be turned on when the output voltage becomes greater than a predetermined value by controlling the fourth transistor to be turned on.
  12. The initial charging circuit according to claim 4, The first energy storage element and, The second energy storage element and, A voltage monitoring unit that monitors the output voltage of the operational amplifier, The system includes a control unit that controls the initial charging circuit, At least one of the first energy storage element or the second energy storage element supplies power to an external system. The control unit controls the third transistor of the initial charging circuit to turn on when the output voltage falls below a predetermined value.
  13. The initial charging circuit comprises a fourth transistor, one end of which is connected to the output of the operational amplifier and the other end of which is connected to ground. The power supply device according to claim 12, wherein the control unit controls the third transistor to be turned on when the output voltage becomes smaller than a predetermined value by controlling the fourth transistor to be turned on.
  14. A voltage monitoring unit that monitors the output voltage of the second energy storage element, A control unit that controls the initial charging circuit, A switch connected in parallel with the initial charging circuit is provided between the first energy storage element and the second energy storage element. The power supply device according to claim 7, wherein the control unit controls the switch to an ON state when the output voltage becomes greater than a predetermined value.
  15. A voltage monitoring unit that monitors the output voltage of the operational amplifier, A control unit that controls the initial charging circuit, A switch connected in parallel with the initial charging circuit is provided between the first energy storage element and the second energy storage element. The power supply device according to claim 7, wherein the control unit controls the switch to an ON state when the output voltage becomes less than a predetermined value.
  16. The power supply device according to claim 7, The aforementioned system, An energy harvesting device comprising the aforementioned energy harvesting power supply.

Description

This invention relates to an initial charging circuit, a power supply device, and an energy harvesting device. Patent Document 1 describes an environmental monitoring system 1 that "is composed of an energy storage system 100 that stores the power generated by an energy harvesting element in a storage battery, and an external load device 200 that is powered by the energy storage system 100" (paragraph 0021). It also states that "in the energy storage system according to this embodiment, in order to solve the above problem, two types of storage batteries A121 and B122 with different capacities and a switch unit 140 (first switch unit) as a switching mechanism are used" (paragraph 0024). Patent Document 1 WO2015/099158 This figure shows an example of an energy harvesting device 100 including an initial charging circuit 30 in an embodiment of the present invention.This figure shows an example of an initial charging circuit 30 in an embodiment of the present invention.This figure shows a modified example of the initial charging circuit 30 in the embodiment.This figure shows another modified example of the initial charging circuit 30 in the embodiment.This figure shows an example configuration of the voltage divider circuit 34.This figure shows an example of the time variation of each voltage in the energy harvesting device 100 shown in Figure 1.This figure shows another example of the energy harvesting device 100.Figure 7 is a flowchart illustrating the operation of the energy harvesting device 100.This graph shows the time evolution of the voltage at each node and the operation of each component.This figure shows a modified example of the energy harvesting device 100 shown in Figure 7.This figure shows another modified example of the initial charging circuit 30. The present invention will be described below through embodiments, but these embodiments are not intended to limit the scope of the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention. In this specification, when terms such as "identical" or "equal" are used, they may include cases where there are errors due to manufacturing variations, etc. Such errors are, for example, within 10%. Furthermore, in this specification, expressions such as "connected between... and...", "provided between... and...", or "positioned between... and..." do not limit the physical arrangement, but rather mean "electrically connected to... and...". Figure 1 shows an example of an energy harvesting device 100 including an initial charging circuit 30 in an embodiment of the present invention. The energy harvesting device 100 comprises an energy harvesting power supply 10, a power supply device 20, and a system 80. The energy harvesting power supply 10 may be a power source composed of one or more sources, such as solar power generation, vibration power generation, or electromagnetic wave power supply. If the voltage output by these power sources is too low or too high, the energy harvesting power supply 10 may include a boost converter or a buck converter. System 80 is powered by electricity generated by the energy harvesting power supply 10. System 80 is an IoT device composed of sensors that convert physical quantities such as temperature, illuminance, carbon dioxide concentration, alcohol concentration, and odor into electrical signals, a microcomputer that processes the obtained electrical signals, and equipment that communicates with the outside world (e.g., a Bluetooth® communication device). The power supply device 20 is installed between the energy harvesting power supply 10 and the system 80. The power obtained from the energy harvesting power supply 10 is usually small or unstable over time. Therefore, in order to operate the system 80 stably, the power is first stored in an energy storage element such as a capacitor or battery in the power supply device 20, and then supplied to the system 80 from the energy storage element. However, in the case of secondary batteries such as lithium-ion batteries, once they are completely discharged, their large capacity means that it takes an enormous amount of time for the system 80 to recover to a voltage that allows it to operate, during which time the system 80 becomes inoperable. Therefore, the power supply device 20 in this example has a first energy storage element 61 and a second energy storage element 62 with a larger capacity than the first energy storage element 61. The first energy storage element 61 is, for example, an element with a relatively small electrical capacity, such as a ceramic capacitor or a supercapacitor. The second energy storage element 62 is, for example, an element with a relatively large electrical capacity, such as a secondary battery like a nickel-metal hydride battery or a lithium-ion battery. Capacitance comparisons can be performed by comparing the capacitance [F] for capacitors or capacitors, and by comparing