Power supply element

Abstract

The adjustment circuit 9 is connected between the power generation circuit 8, which converts environmental energy into electric power, and the power conversion circuit 11, which converts the electric power of the power generation circuit 8 into a desired form. The adjustment circuit 9 includes a first circuit section 13 and a second circuit section 14. The first circuit section 13 has an input 9a connected to the power generation circuit 8 and an output 9c connected to the power conversion circuit 11. The second circuit section 14 has a connection point P1 connected to the first circuit section 13, a ground point P2 connected to a ground potential (GND), and a capacitor C connected between the connection point P1 and the ground point P2. The magnitude of the output resistance 14R included in the second circuit section 14 is smaller than the magnitude of the output resistance 8R included in the power generation circuit 8. The capacitor C is charged with the electric power output from the power generation circuit 8 and outputs the charged electric power to the power conversion circuit 11.

Description

[Technical field]

[0001] The present disclosure describes impedance matching circuits, power conversion elements and power supply elements. [Background technology]

[0002] A technology that utilizes environmental energy that has not been used until now is attracting attention. The technology that utilizes environmental energy is called energy harvesting. Non-Patent Document 1 discloses a basic system related to energy harvesting. The system of Non-Patent Document 1 has a micro energy transducer, a frequency converter, a control device, and an application unit. Environmental energy is converted into electric power by the micro energy transducer. This electric power is converted into a desired voltage and frequency by the frequency converter. The application unit such as a sensor performs a desired operation by receiving the electric power provided by the frequency converter. The control device performs a necessary control operation for these elements. Patent Document 1 discloses a vibration piezoelectric element for power generation. The technology of Patent Document 1 focuses on the output resistance of the vibration piezoelectric element for power generation. The technology of Patent Document 1 adjusts the impedance to the load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-315362 A [Non-patent literature]

[0004] [Non-Patent Document 1] Chao Lu et al., "Efficient Design of Micro-Scale Energy Harvesting Systems," IEEE JOURNAL ON EMERGING AND SELECTED TOPICS IN CIRCUITS AND SYSTEMS, (USA), IEEE, September 2011, No. 3, Vol. 1, pp. 254-266. Summary of the Invention [Problem to be solved by the invention]

[0005] The power generation element used in energy harvesting has a low output voltage. Therefore, the power of the power generation element is provided to the power conversion element. The power conversion element converts the power of the power generation element into a required power form. The transmission of power from the power generation element to the power conversion element is affected by the relationship between the impedance of the power generation element and the impedance of the power conversion element.

[0006] As shown in Patent Document 1, the power generating element has a high output resistance. Therefore, when transmitting power from the power generating element to the power conversion element, it is difficult to maintain the open voltage. In other words, the voltage provided to the power conversion element is lower than the open voltage of the power generating element. The output voltage of the power generating element is low. As a result, the voltage provided to the power conversion element may be lower than the operating voltage of the power conversion element. Therefore, there may be cases where the power generating element cannot provide the desired power.

[0007] Therefore, the present disclosure describes an impedance adjustment circuit that enables efficient power transmission, and a power conversion element and a power supply element that can provide a desired power. [Means for solving the problem]

[0008] One embodiment of the present disclosure is an impedance adjustment circuit connected between a power generation circuit that converts external energy into electric power and outputs the electric power, and a power conversion circuit that converts the electric power generated by the power generation circuit into a desired form. The impedance adjustment circuit includes a first circuit section having an input end connected to the power generation circuit and an output end connected to the power conversion circuit, and a second circuit section having a connection point connected to the first circuit section, a grounding point connected to a ground potential, and a capacitor connected between the connection point and the grounding point. The magnitude of the output resistance included in the second circuit section is smaller than the magnitude of the output resistance included in the power generation circuit. The capacitor is charged with the electric power output from the power generation circuit, and outputs the charged electric power to the power conversion circuit.

[0009] The capacitor of the second circuit section of the impedance adjustment circuit of the present disclosure is charged by the power received from the power generation circuit via the input terminal of the first circuit section. The capacitor transmits the power to the power conversion circuit via the output terminal of the first circuit section. According to this configuration, in a mode in which power is transmitted to the power conversion circuit, the power source of the power conversion circuit is not the power generation circuit but the capacitor. The output resistance between the capacitor and the output terminal is smaller than the output resistance of the power generation circuit. As a result, a circuit configuration in which the impedance adjustment circuit is connected between the power generation circuit and the power conversion circuit can suppress the voltage drop in the power transmitted to the power conversion circuit more than a circuit configuration in which the power generation circuit is directly connected to the power conversion circuit. Therefore, the impedance adjustment circuit can transmit power efficiently.

[0010] Another embodiment of the present disclosure is a power conversion element connected to a power generation element including a power generation circuit that converts external energy into power and outputs the power. The power conversion element includes a power conversion circuit that converts the power generated by the power generation circuit into a desired form, and an impedance adjustment circuit connected between the power generation circuit and the power conversion circuit. The impedance adjustment circuit includes a first circuit section having an input terminal connected to the power generation circuit and an output terminal connected to the power conversion circuit, and a second circuit section having a connection point connected to the first circuit section, a grounding point connected to a ground potential, and a capacitor connected between the connection point and the grounding point. The magnitude of the output resistance included in the second circuit section is smaller than the magnitude of the output resistance included in the power generation circuit. The capacitor is charged with power output from the power generation circuit and outputs the charged power to the power conversion circuit.

[0011] Another type of power conversion element includes the impedance adjustment circuit. Therefore, the circuit configuration of the power conversion element can suppress the voltage drop in the power transmitted to the power conversion circuit, compared to a circuit configuration in which the power generation circuit is directly connected to the power conversion circuit. Therefore, the power conversion element can transmit power efficiently.

[0012] The power conversion element according to another embodiment may further include a control unit that starts and stops the operation of the power conversion circuit. The power conversion element may charge a capacitor when the operation of the power conversion circuit stops. The power conversion element may also discharge a capacitor when the operation of the power conversion circuit starts. This configuration can simplify the configuration of the impedance adjustment circuit.

[0013] In another embodiment, the control unit may control start and stop of the operation of the power conversion circuit based on the magnitude of the voltage provided from the impedance adjustment circuit to the power conversion circuit. With this configuration, it is possible to reliably obtain a desired power from the power conversion circuit.

[0014] In another embodiment, the control unit may switch between starting and stopping the operation of the power conversion circuit every time a predetermined time elapses. This configuration makes it possible to easily control the impedance adjustment circuit.

[0015] In another embodiment, the first circuit section may have a first switch connected to the input terminal and a second switch connected to the first switch and the output terminal. The second circuit section may have a connection point connected to the first switch and the second switch, and a capacitor connected to the connection point and the ground point. The power conversion element may further include a control section that controls the first switch and the second switch. The control section may alternate between a charging operation in which the first switch is controlled to connect the input terminal to the capacitor and the second switch is controlled to disconnect the output terminal from the capacitor, and a discharging operation in which the first switch is controlled to disconnect the input terminal from the capacitor and the second switch is controlled to connect the output terminal to the capacitor. With this configuration, it is possible to reliably switch between the charging operation and the discharging operation.

[0016] In another embodiment, the control unit may control the operations of the first switch and the second switch based on the magnitude of the voltage provided from the impedance adjustment circuit to the power conversion circuit. With this configuration, it is possible to reliably obtain a desired power from the power conversion circuit.

[0017] In another embodiment, the control unit may control the operations of the first switch and the second switch every time a predetermined time elapses. With this configuration, control of the impedance adjustment circuit can be simplified.

[0018] In another embodiment, the power conversion element further includes a first power conversion circuit as the above-mentioned power conversion circuit, a second power conversion circuit separate from the first power conversion circuit for converting the power generated by the power generation circuit into a desired form, and a control unit for controlling the operation of the first power conversion circuit and the second power conversion circuit. The second power conversion circuit is provided in parallel with the impedance adjustment circuit and the first power conversion circuit. The input impedance of the second power conversion circuit is closer to the output impedance of the power generation circuit than the input impedance of the first power conversion circuit. The control unit obtains power from the second power conversion circuit and then obtains power from the first power conversion circuit.

[0019] A power generation element according to yet another aspect of the present disclosure includes a power generation circuit that converts external energy into electric power and outputs the electric power, a power conversion circuit that converts the electric power generated by the power generation circuit into a desired form, and an impedance adjustment circuit connected between the power generation circuit and the power conversion circuit. The impedance adjustment circuit includes a first circuit section having an input terminal connected to the power generation circuit and an output terminal connected to the power conversion circuit, and a second circuit section having a connection point connected to the first circuit section, a grounding point connected to a ground potential, and a capacitor connected between the connection point and the grounding point. The magnitude of the output resistance included in the second circuit section is smaller than the magnitude of the output resistance included in the power generation circuit. The capacitor is charged with the electric power output from the power generation circuit and outputs the charged electric power to the power conversion circuit.

[0020] A power generating element of yet another embodiment includes the impedance adjustment circuit. The power generating element can suppress a voltage drop in the power transmitted to the power conversion circuit, compared to a configuration in which the power generating circuit is directly connected to the power conversion circuit. As a result, power is transmitted efficiently from the power generating circuit to the power conversion circuit. Therefore, the power generating element can provide a desired power. Effect of the Invention

[0021] The impedance adjustment circuit of the present disclosure can efficiently transmit power from the power generation element to the power conversion element, and the power conversion element and power supply element of the present disclosure can provide a desired power. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram showing the configuration of a sensor device using a power supply element according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing the configuration of a power supply element. [Diagram 3] FIG. 3 is an example of a timing chart of a power supply element. [Figure 4] FIG. 4 is a diagram showing the configuration of a power supply element according to the first modification. [Diagram 5] FIG. 5 is a diagram showing the configuration of a power supply element according to the second modification. [Figure 6] FIG. 6 is a diagram showing the configuration of a power supply element according to the third modification. [Figure 7] FIG. 7 is a diagram showing the configuration of a power supply element according to the fourth modification. [Figure 8] FIG. 8 is a diagram showing the configuration of a power supply element according to the fifth modification. [Figure 9] FIG. 9 is a diagram showing the configuration of a power supply element according to the sixth modification. [Figure 10] FIG. 10 is an example of a timing chart relating to the power supply element of the sixth modification. [Figure 11] FIG. 11 is a diagram showing the configuration of a power supply element according to the seventh modification. [Figure 12] 12(a) is a diagram showing the configuration of a power supply element in Study Example 1. FIG. 12(b) is a graph for explaining the results of Study Example 1. [Figure 13] 13(a) is a diagram showing the configuration of a power supply element in Study Example 2. FIG. 13(b) is a graph for explaining the results of Study Example 2. [Figure 14] FIG. 14 is a graph for explaining the results of Study Example 3. [Figure 15] FIG. 15 is a diagram showing a configuration of a sensor device for explaining the background of the eighth modification. [Figure 16] FIG. 16 is a diagram showing the configuration of a power supply element according to the eighth modification. [Figure 17]Part (a) of FIG. 17, part (b) of FIG. 17, and part (c) of FIG. 17 are diagrams for explaining the operation of the power supply element of Modification 8. [Figure 18] Part (a) of FIG. 18, part (b) of FIG. 18, and part (c) of FIG. 18 are diagrams for explaining the operation of the power supply element of Modification 8. [Figure 19] FIG. 19 is a diagram for explaining the effect of the power supply element of the eighth modification. [Figure 20] Part (a) of FIG. 20 and part (b) of FIG. 20 are diagrams for explaining the operation of the power supply element of Modification 8. In FIG. [Figure 21] FIG. 21 is a diagram for explaining the effect of the power supply element of the eighth modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted.

[0024] As shown in Fig. 1, a power supply element 1 is used in a sensor device 2. The sensor device 2 constitutes a so-called IoT (Internet of Things).

[0025] The sensor device 2 is connected to the Internet 300 via an antenna 3. The sensor device 2 transmits collected data to another system such as a cloud 301 via the Internet 300. The sensor device 2 receives various data such as measurement programs via the Internet 300.

[0026] The sensor device 2 includes a power supply element 1 and a sensor element 4. The sensor element 4 collects various data. The various data includes, for example, the temperature, humidity, or vibration frequency of the object 302. The sensor element 4 transmits data. Also, the sensor element 4 receives data from the outside. For example, the sensor element 4 includes a sensor 4a, a digital circuit 4b, a memory circuit 4c, and a communication circuit 4d.

[0027] The power supply element 1 supplies power for driving the sensor element 4. The power supply element 1 supplies power required for the operation of each of the sensor 4a, the digital circuit 4b, the memory circuit 4c, and the communication circuit 4d that constitute the sensor element 4. The power supply element 1 is not a device that stores power in advance, such as a so-called battery. The power supply element 1 obtains power by converting external energy, such as vibration energy, supplied from the object 302. Therefore, the power supply element 1 continues to supply power to the sensor device 2 when vibration energy is supplied from the object 302. The type of vibration that serves as the energy source does not matter. For example, the vibration that serves as the energy source may be sinusoidal vibration. Also, the vibration that serves as the energy source may be random vibration. The sensor device 2 installed on the object 302 continues to supply power by utilizing the vibration energy of the object 302. Therefore, the sensor device 2 does not need to replace the battery.

[0028] The object 302 may include an object 302a and an object 302b that is independent of the object 302a. The object 302a may supply external energy to the power supply element 1. The object 302b may be measured by a sensor 4a.

[0029] The power supply element 1 has an energy conversion element 6 (power generation element) and a power conversion element 7. The energy conversion element 6 converts external energy provided from the object 302 into electric power. The power conversion element 7 converts the electric power provided from the energy conversion element 6 into electric power that can be used to drive the sensor element 4.

[0030] As shown in Fig. 2, the energy conversion element 6 includes a power generation circuit 8. The power generation circuit 8 has outputs 8a and 8b, a power generation unit 8E, and an output resistor 8R. The power generation unit 8E is connected to the output resistor 8R and a ground potential GND. The output resistor 8R is connected to the power generation unit 8E and the output 8a.

[0031] The power generating unit 8E receives energy provided by the object 302. The power generating unit 8E generates electric power using the received energy. The electric power is provided to the output 8a. For example, the power generating unit 8E may be one that utilizes a piezoelectric phenomenon that converts vibration into electric power. The power generating unit 8E has an oscillator such as a cantilever beam. The resonant frequency of the oscillator is adjusted to the vibration frequency of the object 302. The power generating unit 8E generates AC power. The frequency of the AC power corresponds to the frequency at which the oscillator actually vibrates. In other words, the frequency of the AC power output from the power generating unit 8E corresponds to the frequency of the oscillator. The frequency of the AC power output from the power generating unit 8E corresponds to the vibration frequency of the object 302. For example, the frequency of the AC power is several hundred Hertz or more and several megahertz or less.

[0032] The power conversion element 7 is electrically connected to the energy conversion element 6. The power conversion element 7 is electrically connected to the sensor element 4.

[0033] The power conversion element 7 has an impedance adjustment circuit (hereinafter referred to as “adjustment circuit 9”), a power conversion circuit 11, and a control unit 12. The adjustment circuit 9 is connected to the energy conversion element 6 and the power conversion circuit 11. The control unit 12 controls the operations of the power conversion circuit 11 and the adjustment circuit 9.

[0034] The adjustment circuit 9 is connected to the power generation circuit 8 and the power conversion circuit 11. The adjustment circuit 9 adjusts the impedance in the circuit configuration that connects the power generation circuit 8 to the power conversion circuit 11.

[0035] The adjustment circuit 9 has an input 9a (input end), an input 9b, and an output 9c (output end), and an output 9d. The input 9a is connected to the output 8a of the power generation circuit 8. The input 9b is connected to the output 8b of the energy conversion element 6. The outputs 9c and 9d are connected to the power conversion circuit 11.

[0036] A switch S1 (first switch) and a switch S2 (second switch) are arranged between the input 9a and the output 9c. The switch S1 is connected to the input 9a and the switch S2. The switch S2 is connected to the switch S1 and the output 9c. The input 9a, the output 9c and the switches S1 and S2 constitute a first circuit section 13. The switches S1 and S2 are connected to a capacitor C. A line L1 connecting the switch S1 to the switch S2 has a connection point P1. A line L2 connected to the capacitor C is connected to the connection point P1.

[0037] The input 9b is connected to the output 9d. A line L3 connecting the input 9b to the output 9d has a ground point P2. The ground point P2 is connected to one end of the capacitor C. Thus, a reference potential (GND) is provided to the input 9b, the output 9d, and one end of the capacitor C. The connection point P1, the ground point P2, and the capacitor C constitute a second circuit section 14.

[0038] The capacitance of the capacitor C is set, for example, based on the magnitude of the open voltage of the power generation circuit 8, the power required by the power conversion circuit 11, and the power required by the sensor element 4. For example, the capacitance of the capacitor C may be 10 μF.

[0039] The power conversion circuit 11 converts the power output from the adjustment circuit 9 into power according to the specifications of the sensor element 4. Specifically, the voltage of the power output from the power conversion circuit 11 is higher than the voltage of the power output from the adjustment circuit 9. In other words, the power conversion circuit 11 boosts the voltage.

[0040] The power conversion circuit 11 has inputs 11a and 11b and outputs 11c and 11d. The input 11a is connected to the output 9c of the adjustment circuit 9. The input 11b is connected to the output 9d of the adjustment circuit 9. The outputs 11c and 11d are connected to the sensor element 4.

[0041] The power conversion circuit 11 includes a frequency modulation unit 16 and a transformer unit 17. The frequency modulation unit 16 is connected to the inputs 11a and 11b. The frequency modulation unit 16 receives power from the adjustment circuit 9. The frequency modulation unit 16 generates a clock signal. The frequency modulation unit 16 superimposes the clock signal on the output voltage of the adjustment circuit 9. The frequency modulation unit 16 may employ a ring oscillator. The ring oscillator includes, for example, a NAND circuit and an inverter circuit. The frequency of the clock signal generated by the frequency modulation unit 16 may be several megahertz or more. The frequency of the clock signal may be several gigahertz or more. The frequency modulation unit 16 is further connected to the transformer unit 17. The frequency modulation unit 16 provides the voltage on which the clock signal is superimposed to the transformer unit 17.

[0042] The transformer unit 17 is connected to the frequency modulation unit 16. The transformer unit 17 receives the voltage on which the clock signal is superimposed. The transformer unit 17 boosts the voltage on which the clock signal is superimposed. For example, the transformer unit 17 may employ a charge pump. The charge pump includes a plurality of diodes and a plurality of capacitors. The transformer unit 17 is connected to the outputs 11c, 11d. The transformer unit 17 provides power based on the boosted voltage to the outputs 11c, 11d.

[0043] The control unit 12 generates control signals φ1, φ2 for the switches S1, S2 of the adjustment circuit 9. The control unit 12 is connected to the adjustment circuit 9. The control unit 12 provides the control signals φ1, φ2 to the switches S1, S2. The control signal φ1 is provided to the switch S1. The control signal φ2 is provided to the switch S2.

[0044] The operations of the adjustment circuit 9 and the control section 12 will now be described in detail.

[0045] The control unit 12 provides the adjustment circuit 9 with a control signal for the charging operation. Specifically, the control unit 12 sets the control signal φ1 to HIGH and the control signal φ2 to LOW (see period T1 in FIG. 3). The adjustment circuit 9 that receives the control signal φ1 (H) closes the switch S1. That is, the input 9a is connected to the capacitor C. As a result, the capacitor C is charged by the power generated by the power generation circuit 8. Furthermore, the adjustment circuit 9 that receives the control signal φ2 (L) opens the switch S2. That is, the output 9c is disconnected from the capacitor C. As a result, no power is provided to the output 9c. The power conversion circuit 11 is disconnected from the adjustment circuit 9. In other words, the power conversion circuit 11 is disconnected from the power generation circuit 8. Therefore, in the charging operation, the power conversion circuit 11 does not output power.

[0046] After a predetermined time has elapsed since the control signal for the charging operation was provided, the control unit 12 provides the adjustment circuit 9 with a control signal for the discharging operation. Specifically, the control unit 12 sets the control signal φ1 to LOW and the control signal φ2 to HIGH (see period T2 in FIG. 3). The adjustment circuit 9 that receives the control signal φ1 (L) opens the switch S1. That is, the input 9a is disconnected from the capacitor C. As a result, the power generation circuit 8 is disconnected from the adjustment circuit 9. In other words, the power generation circuit 8 is disconnected from the power conversion circuit 11. The adjustment circuit 9 that receives the control signal φ2 (H) closes the switch S2. That is, the output 9c is connected to the capacitor C. In other words, the adjustment circuit 9 is connected to the power conversion circuit 11. As a result, a voltage is provided to the output 9c from the capacitor C. In this state, the impedance (output resistance 8R) of the power generation circuit 8 does not affect the power conversion circuit 11. Therefore, the power conversion circuit 11 can receive a voltage close to the open voltage of the power generation circuit 8. As a result, a voltage that is little affected (or not affected) by a voltage drop is provided to the power conversion circuit 11. The power conversion circuit 11 starts operating with this voltage. Then, the power conversion circuit 11 outputs a boosted voltage.

[0047] In the above description, the control unit 12 presets the length of the period T1 of the charging operation and the length of the period T2 of the discharging operation. That is, the periods T1 and T2 are fixed times. For example, the period T1 of the charging operation is longer than the period T2 of the discharging operation. The power conversion circuit 11 performs power conversion only during the period T2 of the discharging operation. That is, the power conversion circuit 11 provides power to the output 11c only during the period T2 of the discharging operation.

[0048] During the discharging operation, the power conversion circuit 11 is separated from the power generation circuit 8. Here, the adjustment circuit 9 has switches S1 and S2 and a capacitor C. Therefore, the adjustment circuit 9 may ideally be considered to have no output resistance. In an actual circuit configuration, an output resistance 14R exists. However, the output resistance 14R is extremely small. Therefore, the output resistance 14R may be considered to be zero. FIG. 2 illustrates the output resistance 14R. However, the adjustment circuit 9 does not include the output resistance 14R as a resistive element. The output resistance 14R in FIG. 2 explicitly shows, for example, the resistance component of the line connecting the capacitor C to the switch S2. Such a resistance component is usually ignored. This connection configuration is a state in which a power supply with zero impedance is connected to the power conversion circuit 11. Or, a power supply with extremely low impedance is connected to the power conversion circuit 11. Therefore, the voltage of the power supply does not drop due to the relationship between the impedance of the power supply (adjustment circuit 9) and the load (power conversion circuit 11). As a result, power can be efficiently provided from the power generation circuit 8 to the power conversion circuit 11.

[0049] In other words, in order to operate the power conversion circuit 11, it is necessary to generate a predetermined current by providing a predetermined voltage required by the integrated circuit that is the load of the power conversion circuit 11 to the integrated circuit. When the power generation circuit 8 is directly connected to the power conversion circuit 11, the voltage provided to the power conversion circuit 11 drops due to the high impedance (output resistance 8R) of the power generation circuit 8. If there was no voltage drop, it may be possible to obtain the required output current. However, the output current drops significantly due to the voltage drop. On the other hand, by using the adjustment circuit 9, it is possible to realize an ideal state in which the impedance is zero. By using the adjustment circuit 9, it is possible to provide power to the power conversion circuit 11 in an ideal state. As a result, for example, suppose that the period during which the adjustment circuit 9 is connected to the power conversion circuit 11 (period T2 in FIG. 3) is set to 1 / 3 of the period during which the power generation circuit 8 is connected to the adjustment circuit 9 (period T1 in FIG. 3). Even in this case, 1 / 3 of the output current that is not affected by the voltage drop can be provided to the power conversion circuit 11.

[0050] In other words, the adjustment circuit 9 makes it possible to perform power conversion even when the open voltage of the power generation circuit 8 is low. Therefore, even when the energy input to the power generation circuit 8 is low, the energy can be recovered as power.

[0051] [Effects] The power conversion element 7 and the power supply element 1 include an adjustment circuit 9. A capacitor C of the adjustment circuit 9 is charged by power received from the power generation circuit 8 via an input 9a of the first circuit section 13. The capacitor C provides power to the power conversion circuit 11 via an output 9c of the first circuit section 13. In a mode in which power is supplied to the power conversion circuit 11, the power source of the power conversion circuit 11 is not the power generation circuit 8 but the capacitor C. An output resistance 14R existing between the capacitor C and the output 9c is smaller than the output resistance 8R of the power generation circuit 8. As a result, a circuit configuration in which the adjustment circuit 9 is connected between the power generation circuit 8 and the power conversion circuit 11 can suppress a drop in the voltage provided to the power conversion circuit 11 more than a circuit configuration in which the power generation circuit 8 is directly connected to the power conversion circuit 11. Therefore, efficient power transmission can be performed.

[0052] When the external energy (vibration, heat, etc.) input to the power generation circuit 8 is minute, the power output from the power generation circuit 8 is small. For example, in a power generation circuit that utilizes a temperature difference, when the temperature difference given to the power generation circuit is smaller than a predetermined temperature difference, the power required from the power supply element cannot be supplied. On the other hand, the power supply element 1 according to the embodiment can provide power from the power generation circuit 8 to the power conversion circuit 11 without causing a voltage drop. Therefore, the threshold value of the external energy required for supplying power from the power supply element 1 to the sensor element 4 can be lowered.

[0053] The first circuit section 13 has a switch S1 connected to the input 9a, and a switch S2 connected to the switch S1 and the output 9c. The second circuit section 14 has a connection point P1 and a capacitor C. The connection point P1 is connected to the switch S1 and the switch S2. The capacitor C is connected to the connection point P1 and a ground point P2. The power supply element 1 further includes a control section 12 that controls the switches S1 and S2. The control section 12 switches between a charging operation and a discharging operation. In the charging operation, the control section 12 controls the switch S1 to connect the input 9a to the capacitor C. Furthermore, in the charging operation, the control section 12 controls the switch S2 to disconnect the output 9c from the capacitor C. In the discharging operation, the control section 12 controls the switch S1 to disconnect the input 9a from the capacitor C. Furthermore, in the discharging operation, the control section 12 controls the switch S2 to connect the output 9c to the capacitor C. With this configuration, the charging operation and the discharging operation can be reliably switched.

[0054] The control unit 12 controls the operations of the switches S1 and S2 every time a predetermined time elapses. According to this configuration, the control of the adjustment circuit 9 can be simplified.

[0055] Although the embodiment of the present invention has been described, the present invention is not limited to the above embodiment.

[0056] [Variation 1] The control unit 12 periodically switches between the charging operation and the discharging operation every time a preset period has elapsed. The control unit 12A of the power supply element 1A of the first modification may control switching between the charging operation and the discharging operation by using the voltage provided to the output 9c of the adjustment circuit 9. As shown in FIG. 4, the power supply element 1A of the first modification has a line L4 connected to the output 9c of the adjustment circuit 9 in addition to the configuration of the power supply element 1 of the embodiment. A voltage is provided to the output 9c by the discharging operation. This voltage decreases over time. The control unit 12A monitors the voltage provided to the output 9c. The control unit 12A switches from the discharging operation to the charging operation when the voltage provided to the output 9c decreases by a predetermined percentage based on the voltage at the start of the discharging operation. For example, the voltage at the start of the discharging operation is set to 100%. The control unit 12A may switch from the discharging operation to the charging operation when the voltage of the output 9c decreases to 90% or less.

[0057] [Variation 2] As shown in Fig. 5, the power supply element 1B of the second modification has a power generation circuit 8, an adjustment circuit 9B, a power conversion circuit 11, and a control unit 12B. The adjustment circuit 9B, the power conversion circuit 11, and the control unit 12B configure a power conversion element 7B. The adjustment circuit 9B of the second modification has four switches S3, S4, S5, and S6, and two capacitors C1 and C2. In this configuration, the adjustment circuits 9 are connected in parallel.

[0058] Specifically, the switch S3 is connected to the input 9a, the switch S4, and the capacitor C1. The switch S4 is connected to the switch S3, the capacitor C1, and the output 9c. The capacitor C1 is connected to the switches S3, S4, and the ground potential GND. The switch S5 is connected to the input 9a, the switch S6, and the capacitor C2. The switch S6 is connected to the switch S5, the capacitor C2, and the output 9c. The capacitor C2 is connected to the switches S5, S6, and the ground potential GND. The switches S3 and S6 are controlled by a control signal φ1. On the other hand, the switches S4 and S5 are controlled by a control signal φ2. The control unit 12B switches between the charging operation and the discharging operation using the voltage Vin provided to the output 9c of the adjustment circuit 9B. The control unit 12B may periodically switch the operation based on a preset period as in the embodiment.

[0059] When the adjustment circuit 9B charges the capacitor C1, it discharges the capacitor C2. For example, the control unit 12B provides the adjustment circuit 9B with a control signal φ1(H) and a control signal φ2(L). As a result, the capacitor C1 is connected to the power generation circuit 8. Also, the capacitor C1 is disconnected from the power conversion circuit 11. Meanwhile, the capacitor C2 is disconnected from the power generation circuit 8. Also, the capacitor C2 is connected to the power conversion circuit 11. That is, the capacitor C1 is charged. Meanwhile, the capacitor C2 is discharged. For example, the control unit 12B provides the adjustment circuit 9B with a control signal φ1(L) and a control signal φ2(H). As a result, the capacitor C1 is disconnected from the power generation circuit 8. Also, the capacitor C1 is connected to the power conversion circuit 11. Meanwhile, the capacitor C2 is connected to the power generation circuit 8. Also, the capacitor C2 is disconnected from the power conversion circuit 11. That is, the capacitor C1 is discharged. The capacitor C2 is charged.

[0060] The adjustment circuit 9B of the power supply element 1B of the second modification includes two capacitors C1 and C2. As a result, it is possible to increase the period during which power is supplied to the power conversion circuit 11. In other words, it is possible to increase the period during which a voltage is output from the power conversion circuit 11 (voltage conversion period).

[0061] [Variation 3] As shown in FIG. 6, the power supply element 1C of the fourth modification may further include an additional power conversion circuit 18 (second power conversion circuit) in addition to the power generation circuit 8, the adjustment circuit 9, and the power conversion circuit 11 (first power conversion circuit). The additional power conversion circuit 18 is connected to the outputs 8a and 8b of the power generation circuit 8 and the outputs 11c and 11d of the power conversion circuit 11. The additional power conversion circuit 18 is provided in parallel with the adjustment circuit 9 and the power conversion circuit 11. The additional power conversion circuit 18 has a high input impedance that is not affected by the output resistance 8R of the power generation circuit 8. Therefore, the additional power conversion circuit 18 can be operated in the vicinity of the open voltage of the power generation circuit 8. When the power generation circuit 8 is started, the additional power conversion circuit 18 generates power having a predetermined voltage. Then, after the output voltage of the power generation circuit 8 reaches the output voltage during steady operation, the adjustment circuit 9 starts operating with that voltage. With this configuration, the circuit area required for the start-up and steady operation of the adjustment circuit 9 and the power conversion circuit 11 can be reduced. In addition, the power efficiency of the power supply element 1C can be improved.

[0062] [Variation 4] As shown in FIG. 7, the power supply element 1D of the fourth modification includes a power generation circuit 8, an adjustment circuit 9D, a power conversion circuit 11D, and a control unit 12D. The adjustment circuit 9D includes a line L5 and a capacitor C3. The line L5 connects the input 9a and the output 9c. The capacitor C3 is connected to the line L5 and the ground potential GND. The adjustment circuit 9D of the third modification is obtained by removing the switches S1 and S2 from the adjustment circuit 9. The control unit 12D of the third modification is a component of the power conversion circuit 11D. The control unit 12D controls the operation of the power conversion circuit 11D. The control unit 12D is a pulse generator (PG). The control unit 12D controls the start and stop of the transforming operation of the power conversion circuit 11D. The power conversion circuit 11D provides a control signal to the frequency modulation unit 16. The output 11c of the power conversion circuit 11D may be connected to a capacitor C4. The capacitance of the capacitor C4 is preferably smaller than the capacitance of the capacitor C3. However, the magnitude relationship between the capacitors C3 and C4 is not limited to the above relationship. For example, the capacitance of the capacitor C4 may be the same as the capacitance of the capacitor C3. The capacitance of the capacitor C4 may be larger than the capacitance of the capacitor C3.

[0063] With this configuration, the control unit 12D can also switch between the charging operation and the discharging operation of the adjustment circuit 9D. For example, the control unit 12D stops the operation of the power conversion circuit 11D. Stopping the operation of the power conversion circuit 11D means stopping the oscillation of the frequency modulation unit 16. As a result, the power provided from the power generation circuit 8 is charged to the capacitor C3 (charging operation). In a state in which the operation of the power conversion circuit 11D is stopped, the impedance of the power conversion circuit 11D can be considered to be almost infinite (high impedance state). On the other hand, the control unit 12D starts the operation of the power conversion circuit 11D. Starting the operation of the power conversion circuit 11D means starting the oscillation of the frequency modulation unit 16. As a result, power is supplied from the capacitor C3 to the power conversion circuit 11D (discharging operation). In a state in which the power conversion circuit 11D is operating, the impedance of the power conversion circuit 11D can be considered to be in a low impedance state. During the discharging operation, the power output from the power generation circuit 8 is provided to the power conversion circuit 11. However, the operation of the power conversion circuit 11 is governed by the power provided by the capacitor C3. With this configuration, the operation of the switches S1 and S2 can be realized by the operation of the power conversion circuit 11D. Therefore, the switches S1 and S2 can be omitted. As a result, the occurrence of parasitic resistance can be suppressed. The control circuit for the switches S1 and S2 can also be omitted. Therefore, the configuration of the power supply element 1D including the adjustment circuit 9D can be simplified.

[0064] [Variation 5] As shown in FIG. 8, the power supply element 1E of the fifth modification includes a power generation circuit 8, an adjustment circuit 9D, a power conversion circuit 11E, a control unit 12D, and a detection unit 20. The detection unit 20 is connected to the output 11c of the power conversion circuit 11E. The detection unit 20 monitors the voltage provided to the output 11c. The detection unit 20 stops the operation of the frequency modulation unit 16 when the voltage of the output 11c exceeds a threshold value. The detection unit 20 starts the operation of the frequency modulation unit 16 when the voltage of the power conversion circuit 11E falls below the threshold value. When the detection unit 20 stops the operation of the frequency modulation unit 16, the type of the control signal of the control unit 12D is irrelevant. For example, even if the control unit 12 provides the frequency modulation unit 16 with a control signal for starting the operation of the power conversion circuit 11E (starting the oscillation of the frequency modulation unit 16), the frequency modulation unit 16 stops its operation when a control signal for stopping the operation is provided from the detection unit 20. With this configuration, it is possible to set a limit on the output from the power conversion circuit 11E.

[0065] [Variation 6] As shown in FIG. 9, the power supply element 1F of the sixth modification includes a power generation circuit 8, an adjustment circuit 9D, a power conversion circuit 11F, and a clock generation unit 21. The power conversion circuit 11F may be a switching regulator (SW). The switching regulator includes a coil 22, a transistor 23, and a diode 24. In this circuit configuration, the start (see period T1 in FIG. 10) and stop (see period T2 in FIG. 10) of the operation of the power conversion circuit 11F are controlled by a clock signal. The clock signal is provided from the clock generation unit 21 to the diode 24. Therefore, the charge operation and the discharge operation of the adjustment circuit 9D can be switched.

[0066] In short, in the power supply element 1F of the sixth modification, the power conversion circuit is a first power conversion circuit, and further includes a second power conversion circuit separate from the first power conversion circuit for converting the power generated by the power generation circuit into a desired form, and a control unit for controlling the operation of the first power conversion circuit and the second power conversion circuit. The second power conversion circuit is provided in parallel with the impedance adjustment circuit and the first power conversion circuit. The input impedance of the second power conversion circuit is closer to the output impedance of the power generation circuit than the input impedance of the first power conversion circuit. The control unit obtains power from the first power conversion circuit after obtaining power from the second power conversion circuit.

[0067] The first power conversion circuit and the second power conversion circuit may be provided as different circuits. Also, the operating conditions of one power conversion circuit may be controlled to switch between the function as the first power conversion circuit and the function as the second power conversion circuit.

[0068] [Variation 7] 11, the power supply element 1G of the seventh modification includes a power generation circuit 8A, an adjustment circuit 9, a power conversion circuit 11G, an additional power conversion circuit 18, and a control unit 12. The power generation circuit 8A includes four outputs 8c, 8d, 8e, and 8f, two output resistors 8Ra and 8Rb, and two power generation units 8Ea and 8Eb.

[0069] An output resistor 8Ra is connected to the output 8c. A power generation unit 8Ea is connected to the output resistor 8Ra. A ground potential (GND) is connected to the output 8d. An output resistor 8Rb is connected to the output 8e. A power generation unit 8Eb is connected to the output resistor 8Rb. A ground potential (GND) is connected to the output 8f. The output resistance 8Ra is greater than the output resistance 8Rb. The outputs 8e and 8f are connected to the adjustment circuit 9. The outputs 8c and 8d are connected to an additional power conversion circuit 18. The output of the additional power conversion circuit 18 is connected to the adjustment circuit 9 and the power conversion circuit 11.

[0070] In this circuit configuration, the additional power conversion circuit 18 autonomously starts the voltage conversion operation. The additional power conversion circuit 18 supplies the voltage Vctrl The power conversion circuit 11G includes a detection unit 25. The detection unit 25 detects a voltage V ctrl The detection unit 25 monitors the magnitude of the voltage V ctrl is higher than the threshold value, the power conversion circuit 11G starts operating. As a result, the power supply element 1G can provide the desired power.

[0071] [Study example 1] In Study Example 1, the theoretical limit of the open circuit voltage of the power generation circuit was confirmed. Part (a) of FIG. 12 shows a model of a power supply element 100 according to Study Example 1. The power supply element 100 of Study Example 1 includes a power generation circuit 101 and a power conversion circuit 102. The power generation circuit 101 includes a thermoelectric element (TEG). The power supply element 100 supplies a power P OUT The power generation circuit 101 has an output resistance R TEG The power generation circuit 101 has an open circuit voltage V OC The power P is given by IN The power conversion circuit 102 has a conversion efficiency η. The power conversion circuit 102 outputs a power P OUT The load 103 outputs a current I PP and voltage V PP The power required is indicated by and.

[0072] First, the operation of the power conversion circuit 102 is represented by equation (1).

number

[0073] The condition for efficient power transfer from the power generation circuit 101 to the power conversion circuit 102 is expressed by the formula (2). CONV―LOAD The output resistance R of the power generation circuit 101 TEG The aim is to make it consistent with

number

[0074] When the condition shown in formula (2) is satisfied, formula (3) holds.

number

number

[0075] Using equation (4), the relationship between the conversion efficiency η of the power conversion circuit 102 and the theoretical limit of the open circuit voltage lower limit of the power generation circuit 101 was confirmed. In the study example 1, the following conditions were set. Voltage of load 103 V PP :3.3V. Current I of load 103 PP :30μA (condition 1-1), 3μA (condition 1-2). Output resistance R of the power generation circuit 101 TEG :300 ohms.

[0076] Part (b) of FIG. 12 shows the conversion efficiency η of the power conversion circuit 102 and the open voltage V OC The horizontal axis shows the conversion efficiency η. The vertical axis shows the open voltage V OC Graph G1 shows the result under condition 1-1. Graph G2 shows the result under condition 1-2. Compare graphs G1 and G2. The difference between graphs G1 and G2 is the open circuit voltage V OC The lower limit of V OC_MIN According to the graphs G1 and G2, when the conversion efficiency η is 30% or more, the open voltage V OC The lower limit of V OC_MIN It was found that the effect of improving the current I PP and the lower limit V of the open circuit voltage of the power generation circuit 8 OC_MIN The relationship between the open circuit voltage and the minimum open circuit voltage is shown in Equation (5). OC_MIN It has been found that depends strongly on the output conditions of the power conversion circuit 102.

number

[0077] [Study example 2] In the second study, the load 103 is kept constant, and the conversion efficiency η of the power conversion circuit 102 and the open voltage V of the power generation circuit 8 are calculated when the adjustment circuit 104 is applied. OC The relationship between the above and the power supply element 200 was examined. Part (a) of FIG. 13 shows a model of the power supply element 200 in the second examination example. The power supply element 200 includes a power generation circuit 101, a power conversion circuit 102, and a regulation circuit 104. In the second examination example, the condition of the load 103 is kept constant (current I PP =30uA, voltage V pp = 3.3 V). The output resistance R TEG The graph G3 shows the conversion efficiency η and the open voltage V OC Graph G4 shows the relationship between the conversion efficiency η and the open voltage V OC As shown in the graph G3, by applying the adjustment circuit 104, the minimum open voltage V OC_MIN It was found that it can be reduced to 1 / 2.

[0078] [Study example 3] The power supply element 1 including the adjustment circuit 9 has a high efficiency in transferring power. As a result, the power supply element 1 including the adjustment circuit 9 can reduce the circuit scale to obtain a desired power. In the third study, the circuit area of ​​the power supply element 1 including the adjustment circuit 9 was compared with the circuit area of ​​a power supply element 200 (comparative example) not including the adjustment circuit 9. Part (a) of FIG. 14 shows the output voltage V dd and the circuit area A of the power conversion circuit tot Part (b) of FIG. 14 shows the relationship between the output voltage V dd and the conversion efficiency η of the power conversion circuit.

[0079] The common conditions are as follows: Output resistance R of the power generation circuit S :500Ω. Output current I from the power conversion circuit PP : 40μA.

[0080] The conversion efficiency η of the power conversion circuit of the power supply element (comparative example) not including the adjustment circuit 9 is set to 20%. As a result, the input current I dd is 200μA (I dd =I PP / η). The output resistance is 500Ω and the input current I ddが , 200μA, the voltage drop is 0.1V (Rs×I dd ) The output voltage Vdd of the power generation circuit is assumed to be 0.2 V. Then, the input voltage provided to the power conversion circuit is 0.1 V. Refer to the graph shown in part (a) of FIG. 14. According to this graph, the circuit area of ​​the power conversion circuit operating at 0.1 V is 2.5 mm 2 The graph in part (a) of FIG. 14 shows the output current I PP This is the result when the output current I required for the power conversion circuit is 10 μA. PP If the current is 40μA, then four times that (2.5mm 2 It was found that the circuit area required was 1 × 4.

[0081] Next, the circuit area of ​​the power supply element 1 including the adjustment circuit 9 was confirmed. The capacitance of the capacitor C of the adjustment circuit 9 was set to 10 μF. The operating conditions of the adjustment circuit 9 were a charging operation time of 3.5 msec and a discharging operation time of 1.0 msec. According to this operation, the output voltage from the capacitor C was set to 0.2 V ± 10 mV. When the adjustment circuit 9 is provided, there is no need to consider voltage drops. Therefore, the input voltage provided to the power conversion circuit 11 is 0.2 V. According to part (a) of FIG. 14, the circuit area of ​​the power conversion circuit 11 operating at 0.2 V is approximately 0.4 mm. 2 It was found to be.

[0082] According to FIG. 14(b), the conversion efficiency of the power conversion circuit 11 operating at 0.2 V was 30%. That is, the output current I PP The current I PPis output for a predetermined period. Therefore, the current I PP_AVG The average value of the required output current I PP If the current is 40μA, the circuit area (approximately 1.2mm2) will be about three times that (40μA / 13μA). 2 =0.4mm 2 In other words, under the assumed conditions, it was found that the power supply element 1 including the adjustment circuit 9 can have a smaller circuit area than the power supply element not including the adjustment circuit 9.

[0083] [Study example 4] In study example 4, the relationship between the output resistance 8R of the power generation circuit 8 and the circuit area of ​​the power conversion circuit 11 was confirmed. Furthermore, the relationship between the output resistance 8R of the power generation circuit 8 and the conversion efficiency η was also confirmed. For comparison, the relationship between the output resistance 8R and the circuit area, and the output resistance 8R and the conversion efficiency η were also confirmed for a case in which the adjustment circuit 9 was not provided. The set conditions and the results are shown in Table 1. Note that the notations in parentheses in the columns for circuit area and conversion efficiency η are ratios based on condition 3-3 (or condition 3-4). [Table 1]

[0084] In the power supply element (comparative example) without the adjustment circuit 9, the voltage drop was twice as much (0.2 V). For example, in the power supply element (comparative example) without the adjustment circuit 9, the voltage V ddis 0.3V, the voltage provided to the power conversion circuit is 0.1V (0.3V-0.2V). On the other hand, the power supply element 1 including the adjustment circuit 9 operates intermittently. Therefore, the average value of the output current of the power supply element 1 decreases. As a result, the power supply element 1 needs to increase the circuit area to compensate for the decrease in the average value of the output current. However, the power supply element 1 does not need to take voltage drops into consideration. Therefore, a voltage of 0.3V is provided to the power conversion circuit 11 of the power supply element 1. As a result, the output current density of the power supply element 1 is improved. The effect of the increase in current density is about one order of magnitude greater than the effect of the increase in circuit area. As a result, the circuit area of ​​the power supply element 1 is 0.3mm 2 It can be said that:

[0085] Focus on the circuit area under conditions 3-1 and 3-2. When the output resistance 8R was set to 500Ω, the circuit area was 1 / 8 of that of the comparative example (condition 3-3). On the other hand, when the output resistance 8R was set to 1000Ω, the circuit area was 1 / 30 of that of the comparative example (condition 3-3). In other words, it was found that the circuit area can be reduced when the output resistance 8R is large. As a result, it was found that even if the output resistance 8R of the power generation circuit 8 is large, a good design can be achieved by increasing the open voltage. For example, the number of energy harvesting elements is set to a predetermined number. The number of energy harvesting elements connected in series is doubled. The number of energy harvesting elements connected in parallel is halved. As a result, it was found that the open voltage can be doubled. It was also found that the output resistance can be doubled. As a result, the required circuit area is reduced. Therefore, it was found that the design freedom of the power supply element 1 can be increased.

[0086] [Variation 8] FIG. 15 shows the configuration of a sensor device 2 as an IoT terminal. An energy conversion element 6 including a power generation circuit 8 converts the power (P IN ) is output from the energy conversion element 6. IN ) is converted to a voltage (V OUT ) is converted into this voltage (V OUT) is provided to a sensor element 4 (load element) connected to a power conversion element 7. The sensor element 4 includes a sensor 4a and a communication circuit 4d such as a wireless IC.

[0087] The operating power of these elements constituting the sensor element 4 is about 10 mW. For example, during a period when the sensor element 4 does not need to operate, the sensor element 4 is put into a dormant state. By operating in this manner, the average power of the sensor element 4 can be about 10 μW.

[0088] The environmental energy sources include sunlight, heat, vibration, radio waves, etc. The open voltage (V OC ) is often 1 V or less. Therefore, when the output of the energy conversion element 6 is used to drive the sensor element 4, power conversion (boosting) is required.

[0089] In the connection between the energy conversion element 6 that outputs power and the power conversion element 7 that receives the power, it is desired to transfer power efficiently from the energy conversion element 6 to the power conversion element 7. Therefore, it is desired that the transfer efficiency from the energy conversion element 6 to the power conversion element 7 satisfies a desired value. An example of the desired value is the maximum value of the transfer efficiency from the energy conversion element 6 to the power conversion element 7. In order to obtain the maximum transfer efficiency, a connection configuration that satisfies the so-called impedance matching condition is adopted. The impedance matching condition is as follows: the first condition is that the input resistance of the power conversion element 7 is set to the output resistance (R ET ) as the second condition. IN ) is the open circuit voltage (V OC ) (V OC / 2).

[0090] The second condition is the open voltage (V OC ) (V OCThe condition for maximizing the power transfer efficiency may take various forms depending on the type of the energy conversion element 6. The second condition may be set as appropriate depending on the type of the energy conversion element 6.

[0091] In other words, the power conversion element 7 is a voltage (V OC The prerequisite is that the device can operate at a voltage of V OC The prerequisite is that the power conversion element 7 that receives the open voltage (V OC ) is low. Then, the voltage (V OC To obtain an open voltage (V OC ) needs to be increased. OC ) corresponds to the magnitude of the environmental energy. That is, a high open circuit voltage (V OC In other words, without a large amount of environmental energy, the sensor device 2 cannot operate.

[0092] Therefore, in the eighth modification, a power supply element is provided that expands the range of environmental energy capable of driving the load element. In other words, a circuit is provided for operating the sensor device 2 even with low environmental energy. In short, the eighth modification provides a circuit for expanding the open voltage (V OC In other words, the eighth modification provides a power supply element that is a circuit system that minimizes the input energy (environmental energy) to the energy conversion element 6 that can drive the sensor element 4. 0.5 A power supply element that is a circuit system that minimizes

[0093] As shown in FIG. 16, a power supply element 1H of the eighth modification includes a power generating circuit 8, a power conversion element 7H, and a control unit 12H (control unit).

[0094] The power conversion element 7H includes a regulation circuit 9D and a power conversion circuit 11H. The power conversion circuit 11H receives a voltage (V IN ) is received by the power conversion circuit 11H. IN ) is boosted to a voltage (V OUT The power conversion circuit 11H includes an oscillation circuit 16H and a boost circuit 17H.

[0095] The oscillator circuit 16H generates a clock signal (CLK) for the boost circuit 17H. The oscillator circuit 16H provides the clock signal (CLK) to the boost circuit 17H. The oscillator circuit 16H receives a control signal (V _CONTROL ) based on the control signal (V _CONTROL ) is proportional to the magnitude of the voltage of the control signal (V _CONTROL When the voltage of the control signal (V _CONTROL When the voltage of the clock signal (CLK) is small, the frequency of the clock signal (CLK) is low.

[0096] The boost circuit 17H generates a voltage (V IN ) and a clock signal (CLK). The boost circuit 17H then generates a voltage (V IN ) is boosted.

[0097] The control unit 12H generates a control signal (V _CONTROL ) is output. The control unit 12H outputs a voltage (V S ), voltage (V IN ), voltage (V OUT ), target voltage (V IN_TARGET ), target voltage (V OUT_TARGET ) based on the control signal (V _CONTROL ). Therefore, the control unit 12H generates a voltage (V S ) is received by the control unit 12H, which is connected to the output 9c of the adjustment circuit 9D. IN) is received by the control unit 12H, which is connected to the output 11c of the power conversion circuit 11H. OUT The control unit 12H receives a target voltage (V IN_TARGET ) and target voltage (V OUT_TARGET ) is received by the control unit 12H. S ), voltage (V IN ), voltage (V OUT ) based on the target voltage (V IN_TARGET ) may be generated.

[0098] The operation of the control unit 12H will be described in detail below, with reference to Figures 17, 18, and 19 as appropriate.

[0099] Graphs G17a, G17b, and G17c in parts (a), (b), and (c) of Fig. 17 show the relationship between the power and voltage received by the power conversion element 7H. In each diagram, the horizontal axis shows the voltage (V) received by the power conversion element 7H. The vertical axis shows the power (P) received by the power conversion element 7H. Furthermore, Q17a, Q17b, and Q17c show the operating points of the power supply element 1H.

[0100] Part (a) of FIG. 18, part (b) of FIG. 18, and part (c) of FIG. 18 show the relationship between the current and voltage received by the power conversion element 7H. In each figure, the horizontal axis shows the voltage (V) received by the power conversion element 7H. The vertical axis shows the current (I) received by the power conversion element 7H. The voltage (V) received by the power conversion element 7H may be considered as the voltage (V) output by the energy conversion element 6. Similarly, the current (I) received by the power conversion element 7H may be considered as the current (V) output by the energy conversion element 6. Graphs G18a and G18c show the relationship between the output voltage and the output current of the energy conversion element 6. Graphs G18b, G18d, and G18e show the relationship between the input voltage and the input current of the power conversion element 7H. When power is provided from the energy conversion element 6 to the power conversion element 7H, the output current of the energy conversion element 6 and the input current of the power conversion element 7H are the same. Therefore, for example, the point where the graph G18a and the graph G18b intersect indicates the operating point of the power supply element 1H. In other words, Q18a, Q18b, and Q18c indicate the operating point of the power supply element 1H.

[0101] It has already been mentioned that the connection between the energy conversion element 6 and the power conversion element 7H satisfies the impedance matching condition. To state the impedance matching condition again, the first condition is that the input resistance of the power conversion element 7H is equal to the output resistance (R ET ), and the second condition is to match the input voltage (V IN ) is the voltage (V OC The object is to control the power conversion element 7H so that the output voltage Vout becomes equal to or larger than the reference voltage Vout.

[0102] Now, assume that the minimum output voltage required by the sensor element 4 from the power conversion element 7H is set. As a result, the input voltage required for the power conversion element 7H to obtain this output voltage is determined. Then, the output voltage (V OC_MIN ) (first voltage) is determined.

[0103] Please refer to FIG. 17(a) and FIG. 18(a). Let us assume that sufficient environmental energy is provided to the energy conversion element 6. At this time, the energy conversion element 6 is supplied with a voltage (V OC1 In order to satisfy the impedance matching condition, the operating voltage of the power conversion element 7H is the voltage (V OC1 / 2) (second voltage). This state is shown by the operating point Q17a in part (a) of FIG. 17 and the operating point Q18a in part (a) of FIG. 18. If sufficient environmental energy is provided to the energy transfer element 6, the voltage (V OC1 / 2) is the voltage (V OC_MIN ) is greater than the voltage (V OC1 / 2) is the voltage (V OC_MIN ) can be satisfied.

[0104] The voltage (V OC ) increases or decreases depending on the magnitude of the environmental energy received by the energy conversion element 6. For example, assume that the environmental energy received by the energy conversion element 6 decreases. When the environmental energy received by the energy conversion element 6 decreases, the output characteristics (graphs G17b and G18c) of the energy conversion element 6 change as shown in part (b) of FIG. 17 and part (b) of FIG. 18.

[0105] When the environmental energy received by the energy transfer element 6 decreases, the voltage (V OC2 ) is output. OC2 ) is the voltage (V OC1 In this case, the power conversion element 7H is operated so as to satisfy the impedance matching condition (see FIG. 17(b) and FIG. 18(b)). That is, as shown by an operating point Q17b in FIG. 17(b) and an operating point Q18b in FIG. 18(b), the operating voltage of the power conversion element 7H is set to a voltage (V OC2 / 2). Then, the voltage (V OC2 / 2) is the voltage (V OC_MIN ) may not be satisfied.

[0106] In other words, the power conversion element 7H is driven so as to always satisfy the impedance matching condition without responding to the increase or decrease in the environmental energy received by the energy conversion element 6. In that case, the voltage required to drive the sensor element 4 (V OC_MIN ) may not be satisfied.

[0107] Therefore, the power supply element 1H changes the driving condition of the power conversion element 7H in response to an increase or decrease in the environmental energy received by the energy conversion element 6. Specifically, when the environmental energy decreases, the operating voltage of the power conversion element 7H is changed to a voltage (V OC This state is shown by an operating point Q17c in part (c) of FIG. 17 and an operating point Q18c in part (c) of FIG. 18. In other words, as shown in part (c) of FIG. 17 and part (c) of FIG. 18, when the environmental energy decreases, the required voltage (V OC_MIN ) is given priority. As a result, as shown in graph G19a of Fig. 19, the range of environmental energy in which the circuit can be operated can be expanded from range B1 to range B2. In other words, the minimum value of the environmental energy in which the circuit can be operated can be set to a smaller value.

[0108] The first control and the second control performed by the control unit 12H will be described below.

[0109] <First control by the control unit> The first control is a control that prioritizes the condition of satisfying impedance matching. The state in which the first control is selected is called a standard state. The control unit 12H selects the impedance matching condition (V OC / 2=V IN ) and the voltage (V OC / 2) and required voltage (V OC_MIN For example, the control unit 12H compares the voltage (V OC / 2) is the required voltage (V OC_MIN ) if (V OC / 2=VOC_MIN ) may select the first control. Also, for example, the control unit 12H may select the first control for the voltage (V OC / 2) is the required voltage (V OC_MIN ) or more (V OC / 2 ≥ V OC_MIN ) may select the first control. Furthermore, for example, the control unit 12H may select the first control for the voltage (V OC / 2) is the required voltage (V OC_MIN ) multiplied by a specified coefficient (a) (V OC / 2>a×V OC_MIN ) to select the first control. The predetermined coefficient (a) may be, for example, 0.8. When it is determined that the first control is to be performed, the control unit 12H selects the target voltage (V IN_TARGET ) to voltage (V OC / 2). Such a selection operation may be repeatedly performed at any timing during the operation of the power supply element 1H.

[0110] When the control unit 12H selects the first control, the oscillator circuit 16H provides the boost circuit 17H with a clock signal (CLK) shown in part (a) of FIG. 20. Graphs G21b and G21c in part (a) of FIG. 20 show the input voltage (V IN ) and output voltage (V OUT ) is shown.

[0111] In this disclosure, the input voltage (V IN ) was set under the condition that maximizes the efficiency of power transfer from the energy conversion element 6 to the power conversion circuit 11H. IN ) may be set from a different viewpoint than the above conditions. For example, the input voltage (V IN ) may correspond to an operating point at which a higher power can be obtained than the power obtained at the minimum operating point, relative to the power obtained at the minimum operating point. This minimum operating point is the open voltage (V OC ) is an operating point that is set in the vicinity of

[0112] <Second control by the control unit> The second control is the required voltage (V OC_MIN ) is satisfied. The state in which the second control is selected is called a minimum energy state. The control unit 12H, like the first control, OC / 2=V IN ) and the voltage (V OC / 2) and required voltage (V OC_MIN For example, the control unit 12H compares the voltage (V OC / 2) is the required voltage (V OC_MIN ) is smaller than (V OC / 2 <V OC_MIN ) may select the second control. Also, for example, the control unit 12H may select the second control for the voltage (V OC / 2) is the required voltage (V OC_MIN ) multiplied by a specified coefficient (a) (V OC / 2 <a×V OC_MIN ) may select the second control. The predetermined coefficient (a) may be, for example, 0.8. When it is determined that the second control is to be performed, the control unit 12H selects the target voltage (V IN_TARGET ) to voltage (V OC When the control unit 12H determines that the second control is to be performed, the control unit 12H sets the target voltage (V IN_TARGET ) to voltage (V OC_MIN ) multiplied by a predetermined coefficient (b) (V IN_TARGET =b×V OC_MIN In other words, when the control unit 12H determines that the second control is to be performed, the control unit 12H sets the target voltage (V IN_TARGET ) to voltage (V OC / 2) and the voltage (b × V OC_MIN ) may be set to a value smaller than the threshold voltage Vcc. Such a selection operation may be repeatedly performed at any timing during the operation of the power supply element 1H.

[0113] When the control unit 12H selects the second control, the oscillator circuit 16H provides the boost circuit 17H with a clock signal (CLK) shown in part (b) of FIG. 20. Graphs G21e and G21f in part (b) of FIG. 20 show the input voltage (V IN ) and output voltage (V OUT ) is shown.

[0114] Here, the clock signal (CLK) (graph G21d) during the second control has a lower frequency than the clock signal (CLK) (graph G21a) during the first control. When the frequency of the clock signal (CLK) is high, the number of times that the capacitor C is discharged is large. Therefore, the average input current and average input power to the power conversion element 7H are high. The average input voltage to the power conversion element 7H is low. On the other hand, when the frequency of the clock signal (CLK) is low, the number of times that the capacitor C is discharged is small. Therefore, the average input current and average input power to the power conversion element 7H are low. The average input voltage to the power conversion element 7H is high. In other words, by making the clock signal (CLK) relatively low, the voltage (V IN ) can be increased.

[0115] The switching between the first control and the second control is based on the frequency of the clock signal (CLK) of the oscillation circuit 16H. Therefore, when the control unit 12H selects the first control, the control unit 12H generates a control signal (V _CONTROL Similarly, when the control unit 12H selects the second control, the control unit 12H outputs a control signal (V _CONTROL ) is output. The frequency of the clock signal (CLK) is _CONTROL For example, the control signal (V _CONTROL ) is the voltage of the control signal (V _CONTROL ) voltage.

[0116] In other words, the frequency of the clock signal (CLK) may be determined by the ratio of the discharge period (Ta) to the discharge period (Tb, Tc). That is, the period (High) when the voltage of the clock signal (CLK) is high is the discharge period, and the period (Low) when the voltage of the clock signal (CLK) is low is the charge period. For example, the ratio of the discharge period (Ta) to the charge period (Tc) in the second control is lower than the ratio of the discharge period (Ta) to the charge period (Tb) in the first control.

[0117] The relationship of the clock signal (CLK) may be defined by a so-called duty ratio. For example, the duty ratio during the first control is Ta / (Ta+Tb). The duty ratio during the second control is Ta / (Ta+Tc). The duty ratio during the second control is smaller than the duty ratio during the first control.

[0118] In short, the power supply element 1H of the eighth modification is a power supply element connected to a load element. The power supply element includes a power generation circuit that converts external energy into electric power and outputs the electric power, a power conversion circuit that converts the electric power generated by the power generation circuit into a desired form, an impedance adjustment circuit including a first circuit section having an input terminal connected to the power generation circuit and an output terminal connected to the power conversion circuit, and a second circuit section having a connection point connected to the first circuit section, a ground point connected to a ground potential, and a capacitor connected between the connection point and the ground point, and a control section that controls the power conversion circuit. When the second voltage is smaller than the first voltage, the control section controls the operation of the power conversion circuit so that the input voltage to the power conversion circuit is larger than the second voltage. The first voltage is an input voltage to the power conversion circuit that enables the power conversion circuit to output a voltage required for the power conversion circuit to drive a load element. The second voltage is an input voltage to the power conversion circuit that provides a desired power transfer efficiency from the power generation circuit to the power conversion circuit.

[0119] The control unit may control the operation of the power conversion circuit such that, when the first voltage is equal to or higher than the second voltage, an input voltage to the power conversion circuit becomes the second voltage.

[0120] The control unit may be configured so that a ratio of a period during which the capacitor is discharged to a period during which the capacitor is charged when the second voltage is smaller than the first voltage is smaller than a ratio of a period during which the capacitor is discharged to a period during which the capacitor is charged when the first voltage is equal to or greater than the second voltage.

[0121] The power supply element 1H that operates in this way has a circuit operating point of the power conversion element 7H at a voltage (V OC / 2) and open circuit voltage (V OC ) of the energy conversion element 6 capable of driving the sensor element 4. As a result, the IoT terminal can be operated even when the environmental energy is low. In other words, the power supply element 1H can increase the open voltage (V OC The power supply element 1H is a circuit system that minimizes the input energy (environmental energy) to the energy conversion element 6 capable of driving the sensor element 4. 0.5 This is a circuit system that minimizes P out ACT is the power input to the power conversion element 7H. out , P out ACT is the average power of T ACT is the power (P out ACT ) transfer period. T CYC is the power (P out ACT ) is transferred at this time.

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[0122] <Operation Example 1: When the environmental energy received by the energy conversion element 6 decreases> For example, assume that the power supply element 1H is operating in a standard state. In this case, the control unit 12H selects the first control. Then, assume that the environmental energy provided to the energy conversion element 6 is reduced. An example of such a situation is when the temperature difference is reduced when the energy conversion element 6 is an element that generates thermoelectric power. In this case, the output voltage (V OC ) decreases. Then, as a result of the control selection operation performed by the control unit 12H, the selection condition for the first control is not satisfied, but the selection condition for the second control is satisfied. In other words, the state is switched from the standard state to the minimum energy state. Therefore, the control unit 12H switches from the first control to the second control. With this operation, it is possible to continue supplying power to the sensor device 2 even if the environmental energy is reduced.

[0123] <Operation Example 2: When the environmental energy received by the energy conversion element 6 increases> For example, assume that the power supply element 1H is operating in the lowest energy state. In this case, the control unit 12H selects the second control. Then, assume that the environmental energy provided to the energy conversion element 6 increases. In this case, the output voltage (V OC ) also increases. Then, as a result of the control selection operation performed by the control unit 12H, the selection condition for the first control is satisfied. In other words, the minimum energy state is switched to the standard state. Therefore, the control unit 12H switches from the second control to the first control. With such an operation, it is possible to maximize the efficiency of power transfer from the energy conversion element 6 to the power conversion element 7H.

[0124] <Example 3> The control unit 12H may further control the output of the power conversion element 7H. For example, assume that the operation of the power supply element 1H is to be started. First, the control unit 12H sets the target voltage (V IN_TARGET ) is set. When starting operation, it is assumed that the above-mentioned minimum energy state is in effect. Therefore, the control unit 12H sets the target voltage (V IN_TARGET ) as voltage (V OC / 2) higher than the voltage (V OC_MINFor example, the control unit 12H sets a value lower than the target voltage (V IN_TARGET ) as voltage (V OC_MIN ) × 0.8. When the operation starts, the output voltage (V OUT ) is the target voltage of the output (V OUT_TARGET In this case, the frequency of the clock signal (CLK) provided to the power conversion element 7H is increased. Therefore, the control unit 12H increases the frequency of the control signal (V _CONTROL In response to this operation, the boost circuit 17H increases the input voltage (V IN ) and the output voltage (V OUT ) is output. Output voltage (V OUT ) rises, and the output voltage (V OUT ) is the target voltage (V OUT_TARGET ) or equal to the target voltage (V OUT_TARGET When the control signal (V _CONTROL ) is output. In addition, the sensor element 4 connected to the power conversion element 7H operates and outputs an output voltage (V OUT ) drops, the control unit 12H starts the boost operation again. In this way, the output voltage is increased to the target voltage (V OUT_TARGET ) is controlled near the

[0125] The above-mentioned first control and second control may be applied to the power supply devices of the embodiment and the modified examples 1 to 7. When the first control and the second control are applied, each power supply device is provided with a signal line that connects the output of the energy conversion circuit and the control unit. In other words, by adding a configuration for inputting a voltage (Vs) to the control unit, it is possible to perform operations that apply the first control and the second control. [Explanation of symbols]

[0126] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G... power supply element, 2... sensor device, 3... antenna, 4... sensor element, 6... energy conversion element, 7, 7B... power conversion element, 8, 8A... power generation circuit, 8E, 8Ea, 8Eb... power generation unit, 8R, 8Ra, 8R... output resistor, 9, 9B, 9D... adjustment circuit, 11, 11D, 11E, 11F, 11G... power conversion circuit, 12, 12A, 12B, 12D... control unit, 13... first circuit unit, 14... second circuit section, 14R...output resistor, 16...frequency modulation section, 17...transformation section, 18...additional power conversion circuit, 20...detection section, 21...clock generation section, 22...coil, 23...transistor, 24...diode, 25...detection section, C, C1, C2, C3, C4...capacitor, GND...ground potential, S1...switch (first switch), S2...switch (second switch), S3 to S6...switch, P1...connection point, P2...ground point, φ1, φ2...control signal.

Claims

1. a power conversion circuit that converts external energy into electric power and outputs the electric power and converts the electric power generated by a power generation circuit into a desired form; an impedance adjustment circuit connected between the power generation circuit and the power conversion circuit; A control unit that controls an operation of the impedance adjustment circuit, The impedance adjustment circuit includes: A first switch connected to the power generation circuit; a second switch connected to the first switch and the power conversion circuit; a capacitor having one end connected to a connection point between the first switch and the second switch and the other end connected to a ground point, The control unit is a charging operation of controlling the first switch to connect the power generation circuit to the capacitor and controlling the second switch to disconnect the power conversion circuit from the capacitor; a discharging operation in which the first switch is controlled to disconnect the power generation circuit from the capacitor, and a discharging operation in which the second switch is controlled to connect the power conversion circuit to the capacitor, and vice versa.

2. The power supply element of claim 1 further comprising the power generation circuit.

3. 3. The power supply element according to claim 1, wherein the power conversion circuit includes a charge pump type boost circuit.

4. The power supply element according to any one of claims 1 to 3, wherein the control unit switches from the discharging operation to the charging operation when the voltage provided from the capacitor to the power conversion circuit drops by a predetermined percentage based on the voltage at the time the discharging operation is started.

5. 4. The power supply element according to claim 1, wherein the control unit alternates between a discharging operation and a charging operation of the impedance adjustment circuit every time a predetermined time elapses.

6. an impedance adjustment circuit connected to a power generation circuit that converts external energy into a first power and outputs the first power, the impedance adjustment circuit including a capacitor that is charged by the first power; a power conversion circuit that receives the second power output by the capacitor and converts the second power into a third power in a desired mode and defined by a third voltage; The power conversion circuit includes: a frequency modulation unit whose input is connected to the capacitor of the power generation circuit and the impedance adjustment circuit, which superimposes a clock signal having a frequency higher than a frequency of a first voltage defining the first power on a second voltage output by the capacitor and defining the second power, and outputs the second voltage on which the clock signal is superimposed; a transformer unit having an input connected to the frequency modulation unit, receiving the second voltage on which the clock signal is superimposed from the frequency modulation unit, and boosting the second voltage on which the clock signal is superimposed to the third voltage; a control unit that provides the frequency modulation unit with a control signal for switching between a charging operation in which the first power is charged from the power generation circuit to the capacitor by stopping an operation of the frequency modulation unit, and a discharging operation in which the second power is supplied from the capacitor to the frequency modulation unit by starting an operation of the frequency modulation unit, A power supply element, wherein the output of the frequency modulation unit is connected to the input of the transformer unit.

7. the power conversion circuit further comprises a detection unit connected to an output of the power conversion circuit for monitoring a voltage provided to the output and for providing a control signal to the frequency modulation unit; 7. The power supply element of claim 6, wherein the detection unit stops operation of the frequency modulation unit when the voltage provided to the output exceeds a threshold value, regardless of the type of control signal that the frequency modulation unit receives from the control unit, and starts operation of the frequency modulation unit when the voltage provided to the output falls below the threshold value.

8. The power supply element according to claim 6 or 7, further comprising the power generation circuit.

9. 9. The power supply element according to claim 6, wherein the transformer section is a charge pump type boost circuit.

10. an impedance adjustment circuit connected to a power generation circuit that converts external energy into a first power and outputs the first power, the impedance adjustment circuit including a capacitor that is charged by the first power; a power conversion circuit that receives the second power output by the capacitor and converts the second power into a third power in a desired manner and defined by a third voltage; a control unit that outputs a control signal for the power conversion circuit, The power conversion circuit includes: a transformer unit that boosts a second voltage that defines the second power output by the capacitor to the third voltage; a frequency modulation unit that outputs a first clock signal or a second clock signal for controlling the transmission of the second power from the capacitor to the transformer unit, an input of the transformer unit is directly connected to the power generation circuit and the capacitor of the impedance adjustment circuit without passing through the frequency modulation unit; an output of the frequency modulation unit is connected to the transformer unit; The frequency modulation unit provides the first clock signal or the second clock signal having a frequency higher than a frequency of the first power to the transformer unit; the control unit compares a first voltage that defines the first power output by the power generation circuit with a required voltage that the power conversion circuit should receive, which is determined based on an output voltage required for the power conversion circuit, and generates the first clock signal in the frequency modulation unit when the first voltage is equal to or greater than the required voltage or when the first voltage is greater than the required voltage multiplied by a predetermined coefficient, and generates the second clock signal in the frequency modulation unit when the first voltage is smaller than the required voltage or when the first voltage is smaller than the required voltage multiplied by a predetermined coefficient; an operating voltage received by the transformer unit upon receiving the first clock signal is half the first voltage and satisfies an impedance matching condition between the power conversion circuit and the power generation circuit; A power supply element, wherein the operating voltage received by the transformer unit upon receiving the second clock signal is higher than 1 / 2 of the first voltage and does not satisfy an impedance matching condition between the power conversion circuit and the power generation circuit.

11. The control unit is providing a first control signal to the frequency modulation unit to cause the frequency modulation unit to generate the first clock signal having a first frequency when the first voltage is equal to or greater than the required voltage; providing a second control signal to the frequency modulation unit to cause the frequency modulation unit to generate the second clock signal having a second frequency when the first voltage is less than the required voltage; The power supply element of claim 10 , wherein the second frequency is lower than the first frequency.

12. The power supply device according to claim 10 or 11, further comprising the power generation circuit.

13. 13. The power supply element according to claim 10, wherein the transformer section is a charge pump type boost circuit.

14. the frequency modulation unit outputs the first clock signal including a first discharging period and a first charging period when receiving the first control signal; outputting the second clock signal including a second discharging period and a second charging period when receiving the second control signal; 12. The power supply device of claim 11, wherein a ratio of the second discharging period to the second charging period is lower than a ratio of the first discharging period to the first charging period.

15. the frequency modulation unit outputs the first clock signal including a first discharging period and a first charging period when receiving the first control signal; outputting the second clock signal including a second discharging period and a second charging period when receiving the second control signal; The power supply device according to claim 11 , wherein a duty ratio of the second clock signal is smaller than a duty ratio of the first clock signal.

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