Power receiving device that performs maximum current point tracking control

Abstract

The present invention provides a feasible and effective concrete method for controlling MCPT with a relatively simple configuration. Provided is a power receiving device for receiving power transmitted from a power transmission device on the basis of a wireless power supply method, the power receiving device comprising: a power receiving antenna which receives electromagnetic waves; a rectifier which converts the electromagnetic waves into a DC voltage; a controller which adjusts the resistance on the output side of the rectifier; and a power storage device which stores the output of the controller, wherein the voltage-current characteristics of the rectifier vary according to the distance between the power transmission device and the power receiving device, and the controller performs maximum current point tracking control by gradually changing the resistance value such that the voltage value on the output side of the rectifier falls below a predetermined threshold value.

Description

[Technical Field]

[0001] The present invention relates to maximum power point tracking control or maximum current point tracking control during power supply. [Background technology]

[0002] Conventionally, maximum power point tracking (MPPT) or maximum current point tracking (MCPT) has been known, which changes the resistance value during power supply to change the voltage and current values ​​to find the optimal operating point.

[0003] Referring to (A) of Figure 22, a circuit for charging a secondary battery with energy generated by a solar cell is illustrated. The output voltage of a solar cell depends on the amount of solar radiation and is generally about 0.1V to 0.5V per cell. The battery voltage of a secondary battery is generally about 3.7V in the case of a lithium-ion battery. Therefore, when charging a secondary battery using a solar cell, a step-up switching regulator may be used to adjust the voltage value.

[0004] Referring to Figure 22(B), for the circuit in Figure 22(A), the horizontal axis shows the resistance value connected from the output terminal of the solar cell to ground, and the vertical axis shows the solar cell's power value. Solar cells change their output power depending on their resistance value, and this is usually shown as a mountain-shaped graph. When a solar cell generates power, the control that tracks the output to the maximum power point (value of current x voltage) on the mountain-shaped graph, in other words, the optimal operating point, is called maximum power point tracking (MPPT).

[0005] As shown in Figure 22(B), controlling the optimum operating point at which power is maximized based on a mountain-shaped graph is also known as the Hill Climbing Method. This control involves, for example, adjusting the on / off ratio of the circuit's switching to change the apparent resistance value connected to the output terminal of the solar cell. The optimum operating point of a solar cell varies depending on the installation location and weather, but by applying MPPT, it is possible to obtain maximum output by appropriately changing the resistance value (see symbols R1, R2, and R3) (see symbols W1, W2, and W3).

[0006] JP 2020-137304 A (Patent Document 1) is a background technology in this technical field. This publication states, "An object of the present invention is to provide a power system that makes it easy to extract large amounts of power from a fuel cell power generation system to a DC power conversion device by performing MPPT control using a DC power conversion device designed to be able to perform MPPT control of a solar power generation system. In particular, the characteristic conversion control is a control that causes the electrical output characteristics of the characteristic conversion circuit 100 to follow look-up table data. The electrical output characteristics represented by the look-up table data are such that the output power is maximized when the output voltage is a certain value within a predetermined range, and the output current decreases as the output voltage increases in a region where the output voltage crosses the certain value" (see Abstract). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-137304 Summary of the Invention [Problem to be solved by the invention]

[0008] Typically, MPPT control methods seek the maximum value of a power graph, which has a mountain-shaped curve. However, because the current graph does not have a mountain-shaped curve, even if the maximum power value is obtained based on MPPT, it does not necessarily mean that the maximum current value is obtained. Performing MCPT instead of or in addition to MPPT can require a relatively complex algorithm. However, when the power capacity of the power supply is limited, the increased power consumption required for the control itself can reduce the efficiency of the entire system.

[0009] Therefore, the present invention provides a practical and effective specific method for controlling MCPT with a relatively simple configuration. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, for example, the configurations described in the claims are adopted. The present application includes a plurality of means for solving the above-mentioned problems, and one example thereof is a power receiving device that receives power transmitted from a power transmitting device based on a wireless power supply system, the power receiving device comprising: a receiving antenna that receives electromagnetic waves; a rectifier operatively connected to the power receiving antenna to convert the electromagnetic waves into a DC voltage; a controller operatively connected to the rectifier for adjusting a resistance on an output side of the rectifier; a power storage device that stores the output of the controller, the voltage-current characteristics of the rectifier change depending on the distance between the power transmitting device and the power receiving device; The controller provides a power receiving device that performs maximum current point tracking (MCPT) by changing the resistance value in stages so that the voltage value on the output side of the rectifier falls below a predetermined threshold. [Effects of the Invention]

[0011] The present invention provides a practical, effective and specific method for controlling MCPT with a relatively simple configuration. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating a schematic example of an embodiment of a power receiving device. [Figure 2] FIG. 2 is a diagram illustrating the output of the rectifier side of the rectenna of the power receiving device using three graphs. [Figure 3] FIG. 3 is a graph illustrating an example of the application of MCPT control. [Figure 4] FIG. 4 is an enlarged view of the main part of FIG. [Figure 5] FIG. 5 is a diagram illustrating a process flow of MCPT control. [Figure 6] FIG. 6 is a diagram illustrating a circuit for implementing step S203 of FIG. [Figure 7] FIG. 7 is a diagram illustrating a circuit for implementing step S204 of FIG. [Figure 8] FIG. 8 is a diagram illustrating a circuit that implements the output logic of FIG. 6 and the output logic of FIG. 7 using a NAND. [Figure 9] FIG. 9 is a diagram illustrating a circuit for implementing steps S205 and S206 in FIG. [Figure 10] FIG. 10 is a diagram illustrating a circuit for implementing steps S205 and S206 in FIG. [Figure 11] FIG. 11 is a diagram showing a modification of the process flow of FIG. [Figure 12] FIG. 12 is a diagram showing a modification in which a buck converter or a boost converter is added to the power receiving device. [Figure 13] FIG. 13 is a diagram showing a modification in which a buck converter and a boost converter are connected in parallel to the power receiving device. [Figure 14] FIG. 14 is a diagram showing a modification in which a buck-boost converter is added to the power receiving device. [Figure 15] FIG. 15 is a graph illustrating the effect of adding a buck converter or a boost converter to a powered device. [Figure 16]FIG. 16 is a diagram showing a modification in which an LDO is added to the power receiving device. [Figure 17] FIG. 17 is a diagram showing a modification in which a transmitter that transmits a feedback signal is added to the power receiving device. [Figure 18] FIG. 18 is a diagram showing a modification in which a transmitter that transmits a feedback signal is added to the power receiving device. [Figure 19] FIG. 19 is a diagram illustrating a power receiving device using an MCPT controller equipped with a memory and a CPU. [Figure 20] FIG. 20 is a diagram illustrating a case where the power receiving device calculates the distance based on the received power. [Figure 21] FIG. 21 is a diagram illustrating a case where the power receiving device receives distance data grasped on the power transmitting device side. [Figure 22] FIG. 22 is a diagram that schematically shows a circuit for charging a secondary battery using a solar cell, and a graph of the resistance and power of the circuit. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment shown below is one embodiment of the present invention, and the content of the present invention should not be interpreted as being limited based on the following description. [Example]

[0014] "Overall configuration of the power receiving device" Referring to FIG. 1A, an embodiment of a power receiving device 1 that receives energy E transmitted from a power transmitting device (Power Tx) 10 is illustrated schematically. The power receiving device 1 can be applied to wirelessly supply power to devices that consume power used in various machines 100 in fields such as factory automation (FA), Internet of Things (IoT), and home appliances.

[0015] The power receiving device 1 can be applied to a variety of applications. In the example shown in Fig. 1, the power receiving device 1 is built into a machine 100 such as an industrial robot (including machine tools) or a household robot (including home appliances). The machine 100 can be configured to be used for a variety of applications, such as clamping, lifting (picking), placing, assembling, painting, and welding a workpiece or component W. For example, the machine 100 is an articulated robot that can move with a high degree of freedom.

[0016] The articulated robot 100 generally has multiple (at least two) axes or joints J1a, J1b, J2a, J2b, and J2c to operate the robot arm unit 110 and / or the robot hand unit 120 with a high degree of freedom. Generally, the more joints J1a, J1b, J2a, J2b, and J2c the articulated robot 100 has, the higher the degree of freedom of movement it can perform, but the more precise control is required. On the other hand, the fewer joints J1a, J1b, J2a, J2b, and J2c the articulated robot 100 has, the simpler its mechanism becomes and the less likely it is to malfunction.

[0017] When wiring to supply power to devices built into the articulated robot 100, problems such as strain on the wiring, wiring breakage, and wiring maintenance may occur due to movement of the joints J1a, J1b, J2a, J2b, and J2c of the articulated robot 100. Furthermore, machines that perform movements with a high degree of freedom, such as the articulated robot 100, generally incorporate various components such as actuators inside, which creates the problem of limited space for adding wiring.

[0018] The power receiving device 1 wirelessly receives the energy E transmitted from the power transmitting device 10. Therefore, even if the power supply target (a device such as a sensor) is built into the articulated robot 100 and its position is frequently changed, it is possible to transmit the necessary power to the power supply target from a remote location and avoid the above-mentioned wiring problem. The power receiving device 1 is also called a power receiver or a power receiving system, but will be referred to hereinafter as the power receiving device 1. The power transmitting device 10, which acts in combination with the power receiving device 1, is also called a power transmitter or a power transmitting system, but will be referred to hereinafter as the power transmitting device 10.

[0019] The power receiving device 1 can be applied to various machines 100 in any desired manner. It is not necessary for all components of the power receiving device 1 to be housed within the fingers of the robot hand unit 120 illustrated in FIG. 1A. In this case, relatively large and bulky components may be configured to be flexible and rolled up and housed within the space of the fingers. Also, some components may be located away from the fingers (for example, at the base of the fingers of the robot hand unit 120 or in a wider area nearby). Also, some components may protrude outside the machine 100 as necessary.

[0020] The power receiving device 1 can be applied to various applications in addition to the illustrated machine 100. For example, the power receiving device 1 may be installed in general FA equipment to supply power to sensors that detect objects on factory lines, such as proximity sensors and magnetic sensors. Furthermore, the power receiving device 1 may be installed in general building management to monitor the status of office environments, such as temperature, humidity, and illuminance sensors.

[0021] Referring again to FIG. 1A, the power transmitting device 10 is placed at an appropriate location outside the articulated robot 100 and transmits energy E wirelessly to the power receiving device 1. There are several types of wireless power transfer, but in this embodiment, wireless power transfer is preferably performed between the power transmitting device 10 and the power receiving device 1 by a microwave method. The microwave method allows energy or power to be transmitted over a relatively long distance. For example, when wireless power transfer is performed using the microwave method, a power capacity of about 1 to 10 mW can be transmitted over a distance of about 1 meter.

[0022] 1(B) illustrates a schematic diagram of components of the power receiving device 1. The power transmitting device 10 is controlled by a controller (not shown) and transmits energy E from a power transmitting antenna unit 12 to the outside. The energy E is received by a rectenna (power receiving antenna) 20 of the power receiving device 1. The rectenna 20 includes a power receiving antenna unit 22 configured to receive energy E from multiple directions, and a rectifier 24 operatively connected to the power receiving antenna unit 22.

[0023] The power receiving antenna unit 22 can have any configuration. The power receiving antenna unit 22 can be configured in various ways, such as a dipole antenna, a monopole antenna, a slot antenna, a chip antenna, or the like. The power transmitting antenna unit 12 and the power receiving antenna unit 22 are separated from each other by a distance d. According to "Friis's Law," the amount of power that can be supplied from the power transmitting device 10 to the receiver attenuates inversely proportional to the square of the distance d.

[0024] Rectifier 24 is an element having a rectifying effect of passing current in only one direction, and converts RF (electromagnetic waves) received by power receiving antenna unit 22 into DC (direct current voltage). Power receiving antenna unit 22 and rectifier 24 may be configured integrally. In this way, rectenna 20 rectifies and converts microwaves into DC current.

[0025] The voltage output from the rectenna 20 is adjusted (VCR: voltage controlled resistance) 30 via a controller or a voltage controlled resistor. out V bat (adjusted to the output V bat is supplied to the power storage device 40. At this time, the current value I bat V out indicates the output voltage value of the rectifier 24, and V bat means the voltage value of the power storage device 40. As will be described later, the VCR 30 performs MCPT control, and therefore can be referred to as an MCPT controller 30 or simply as a controller 30.

[0026] The power storage device 40 is any device that stores electricity internally, and is preferably a secondary battery. A charger (not shown) can be combined with the battery 40. The battery 40 is an electronic component that functions as a battery (chemical battery) that can be used multiple times (not just once) by charging. The battery 40 may be, for example, a lithium-ion battery, a nickel-metal hydride battery, or an all-solid-state battery. However, specific examples of the power storage device 40 are not limited to a battery. Alternatively, the power storage device 40 may be a capacitor. Alternatively, the power storage device 40 may be a combination of a battery and a capacitor. Hereinafter, the power storage device 40 is preferably a secondary battery.

[0027] "Maximum Current Point Tracking (MCPT) Overview" 2A to 2C, three graphs are used to illustrate the output of the rectifier 24 of the rectenna 20 that receives energy transmitted from the power transmitting antenna unit 12 of the power transmitting device 10 in the system of Fig. 1. The power transmitting antenna unit 12 and the power receiving antenna unit 22 are spaced apart by a distance d of 500 mm. Referring to FIG. 2(A), the horizontal axis indicates the resistance value connected from the output terminal of the rectifier to the ground, and the vertical axis indicates the correspondence between voltage (solid line) and current (dashed line). Referring to FIG. 2(B), the horizontal axis indicates the resistance value connected from the output terminal of the rectifier to the ground, and the vertical axis indicates the correspondence between voltage (solid line) and power (dashed line). Referring to FIG. 2(C), the horizontal axis indicates the resistance value connected from the output terminal of the rectifier to the ground, and the vertical axis indicates the correspondence between power (solid line) and current (dashed line).

[0028] 2A, it can be seen that the higher the resistance value, the higher the output voltage value, while the lower the resistance value, the higher the output current value. On the other hand, since power is calculated as the product of current and voltage, it can be seen that power is maximized when the resistance value is an intermediate value (e.g., 20 kΩ), as shown in FIGS. 2B and 2C.

[0029] Wireless power supply based on a microwave system has its own problems, such as a limited amount of transmittable energy. Furthermore, the input impedance of the power storage device 40 may be relatively low compared to the output impedance of the rectifier 24 on the power receiving side. In this case, it is necessary to adjust (increase) the apparent input impedance of the power storage device 40. When appropriately adjusting the input impedance of the power storage device 40, generally, MPPT control is performed by the voltage control resistor 30 so as to adjust the input impedance to the operating point at which the output power of the rectifier 24 is maximized (see FIG. 22).

[0030] As shown in (B) and (C) of FIG. 2, power exhibits a mountain-shaped or convex graph. Therefore, finding the maximum power value is generally called the hill-climbing method. This method is sometimes used in maximum power point tracking (MPPT). However, as can be seen from (B) and (C) of FIG. 2, the maximum power point and the maximum current point do not coincide. For charging the power storage device 40 as in this embodiment, maximizing the current is preferable, so applying MPPT presents a problem.

[0031] In this embodiment, as described above, it is assumed that there is a problem if the output of rectifier 24 is transmitted directly to power storage device 40. However, simply applying MPPT as control is not preferable because it causes a drop in current. This is because MPPT cannot adjust the output current of rectifier 24 to the operating point where it is maximized. Therefore, in this embodiment, VCR 30 performs maximum current point tracking (MCPT).

[0032] Note that the "maximum" in maximum current point tracking control does not mean the absolute maximum value of the current. For example, as shown in Figure 2 (A) and (C), the theoretical maximum current value is undesirable because it minimizes the voltage and current. MCPT aims to maximize the current value within a range that ensures the required voltage or power value.

[0033] As shown in FIG. 1A, for example, when power is supplied to an articulated robot 100, the operable area varies depending on the environment (for example, the robot arm unit 110 and / or the robot hand unit 120 move with a high degree of freedom). This causes the distance d between the power transmitting side and the power receiving side to change, and the operating point at which the output current on the power receiving side is maximized is not constant. To address this issue, it is conceivable to prepare a dedicated algorithm that can handle various environments.

[0034] However, when a dedicated algorithm is prepared, the control itself consumes power. In particular, the more complex the algorithm or the corresponding components are, the more power is likely to be consumed. When wireless power transfer is performed based on a microwave system, the power transfer capacity is limited, so consuming a relatively large amount of power for the control itself may reduce the efficiency of the entire system.

[0035] In particular, in conventional MPPT and MPPT control, control is often performed using a CPU and memory. For example, in the technology disclosed in the above-mentioned Patent Document 1, control is performed using an MCU (microcontroller unit) 51. Typically, an MCU is a microprocessor that incorporates memories such as ROM and RAM, and many peripheral functions such as I / O-related functions. In addition, the control unit 170 includes a memory 173 that stores multiple table data.

[0036] The first embodiment aims to enable MCPT control with low power consumption. 3, an example of application of MCPT control is shown in the diagram shown in FIG. 1(A), in which the horizontal axis indicates resistance and the vertical axis indicates voltage and current. In the diagram, as shown by the two thick horizontal lines, the battery voltage (voltage value of the power storage device 40) V bat The voltage value V has an upper margin ΔV with respect to a predetermined lower value. out is within this range (V bat and V batIt is preferable that the voltage value falls within this range (between +ΔV and +ΔV). Therefore, by changing the resistance value so that the voltage value falls within this range, the current value is changed accordingly (see symbols a, b, and c in FIG. 3).

[0037] Referring to FIG. 4, an enlarged view of a main part of FIG. 3 is shown. As can be seen from Figure 4, when the resistance value increases stepwise (see symbols R1, R2, R3), the voltage value correspondingly increases stepwise (see symbols V1, V2, V3, V4), while the current value correspondingly decreases stepwise (see symbols I1, I2, I3, I4). Obviously, when the resistance value decreases stepwise, the voltage value correspondingly decreases and the current value correspondingly increases.

[0038] In FIG. 4, the output current on the rectifier 24 side is indicated by a dashed curve, the output voltage on the rectifier 24 side is indicated by a solid curve, and the battery voltage V of the power storage device 40 is indicated by a thick straight line. bat And the voltage "V" above this by a certain value ΔV bat In MCPT control, the battery voltage V bat The predetermined upper limit value of "V bat The current value I is maximized so that it falls within the range of "+ΔV". For example, for each value of V4, V3, and V2 in Figure 3, the output voltage value V OUT is the above value "V bat +ΔV”, which is not desirable. On the other hand, at V1 in Figure 4, the output voltage value V OUT is the above value "V bat +ΔV”, which is preferable. In this state, the output voltage value V OUT is the battery voltage V bat It exceeds.

[0039] For example, the battery voltage V bat In the case of general lithium-ion batteries and all-solid-state batteries, the battery voltage V is about 3.7V. bat In the case of semi-solid batteries and lithium titanate batteries, the voltage is about 2.5V.

[0040] Battery voltage V batThe margin indicated by ΔV can be set arbitrarily depending on the embodiment. For example, ΔV is about 100 mV. The finer ΔV is set, the higher the control accuracy becomes, but the power consumption tends to increase. In reality, the minimum value of ΔV is about 10 mV. The maximum value can be set by increasing ΔR, so in theory it can be increased as much as desired, but it is about 10 V, for example.

[0041] The resistance R is preferably variable in steps of equal magnitude ΔR. ΔR can be set arbitrarily depending on the embodiment. For example, ΔR is about 100 Ω. As with ΔV, the finer ΔR increases the control accuracy, but power consumption tends to increase. In reality, the minimum value of ΔR is about 1 Ω. Theoretically, the maximum value can be increased as much as desired, but is, for example, about 1 MΩ.

[0042] By applying MCPT control, it is possible to adjust the apparent input impedance of the power storage device 40. In particular, by using MCPT, it is possible to adjust the operating point to be close to the operating point at which the output current of the rectifier 24 is maximized. This system can be adapted to any environment, and specifically, in rectifier 24, whose voltage-current characteristics change according to distance d, it is possible to charge power storage device 40 with high efficiency under any environment. As will be explained later, this control can be realized using basic electronic circuits and can be configured without the need for high-power devices such as memory or a CPU, which has the excellent effect of enabling the system as a whole to be realized with low power consumption.

[0043] "MCPT flow" 5 illustrates an example of a process flow of MCPT control performed by the VCR 30. In the flow of FIG. 5, MCPT control is started in step S201. This start can be performed at any timing, and may be started, for example, when power is supplied to any device (e.g., a sensor) in the industrial robot 100, in conjunction with the start of use of the industrial robot 100 (such as when the power is turned on).

[0044] When the control is started, the VCR 30 sets the resistance value to an initial value in step S202. For example, the resistance value may be set to a maximum value. out =R max This means that control starts from the rightmost point in the graphs shown in FIG. 3 or FIG. 4.

[0045] The initial value of the resistance is not limited to the maximum value. For example, the battery voltage V bat Depending on the situation, it is possible to set the initial value to an intermediate value (for example, the intermediate value in the graph shown in FIG. 3 or FIG. 4 / a value between the rightmost and the intermediate value in the graph shown in FIG. 3 or FIG. 4). When an intermediate value is selected as the initial value, the value may be a value empirically derived depending on the embodiment by repeating the control multiple times. On the other hand, when the maximum value is selected as the initial value, the above-mentioned empirical derivation work can be eliminated.

[0046] Note that the minimum value (for example, the leftmost value in the graph shown in FIG. 4) is not selected as the initial value. The minimum resistance value is indefinite and depends on the battery voltage (V bat ) varies greatly depending on the Hereinafter, it is assumed that the resistance value is set to the maximum value as the initial value in step S202. out =R max ".

[0047] Next, in step S203, the VCR 30 outputs the output current I out is the predetermined maximum value I bat_max "I out bat_max " For example, in the case of I4 in Figure 4, the output current value I out is the predetermined maximum value I bat_max In other words, it is determined that the desired maximum value of the current is not obtained in this situation.

[0048] Next, if the answer is yes in step S203, the VCR 30 proceeds to step S204 and determines whether the output voltage V out is the predetermined maximum value "V​bat +ΔV”. For example, in the symbol V4 in FIG. 4, the output voltage value V out is the above value "V bat +ΔV”.

[0049] Next, if the answer is yes in step S204, the VCR 30 decreases the resistance by a predetermined amount ΔR in step S205. out =R out -ΔR”. For example, in the graph shown in Figure 4, the resistance is reduced by the amount of R3, which results in a decrease in the voltage from V4 to V3, and a corresponding increase in the current from I4 to I3.

[0050] As the VCR 30 repeats steps S203, S204, and S205, the resistance decreases stepwise (R3, R2, R1), and the voltage correspondingly decreases stepwise (V4, V3, V2, V1) and the current increases stepwise (I4, I3, I2, I1). Preferably, the magnitude of the stepwise change in resistance is the same (R3 = R2 = R1 = ΔR). However, the magnitude of the resistance can vary. For example, a relatively large resistance may be selectable at the far right of FIG. 3 or FIG. 4. Alternatively, a relatively small resistance may be selectable in the middle of FIG. 3 or FIG. 4. As a result of repeating the above steps S203, S204 and S205, it is determined in the above step S204 that the output voltage V out is the predetermined maximum value "V bat For example, in the graph shown in Figure 3, the output voltage V out The value V1 of "V bat As a result, I4 corresponding to V4 can be selected as a suitable current.

[0051] Meanwhile, the VCR 30 outputs the output current I out is the predetermined maximum value I bat_maxIf it is determined that the resistance exceeds ΔR, the result in step S203 is no, so the resistance is increased by a predetermined amount ΔR in step S206. out =R out +ΔR”. Similarly, the output voltage V out is the predetermined maximum value "V bat If it is determined that the resistance is lower than "+ΔV", the result in step S204 is "no", and therefore the resistance value is increased by a predetermined magnitude ΔR in step S206. out =R out +ΔR”. For example, in the graph shown in Figure 3, the output voltage V out The value V0 of "V bat +ΔV. In this case, the resistance is increased by the amount of R0 in the graph shown in Figure 3. As a result, the voltage V0 increases to V1, ensuring the desired voltage value, and the current value is correspondingly reduced.

[0052] Therefore, in the flowchart of FIG. 5, the target voltage value V out However, there are two thresholds, V bat +ΔV” and “V bat It is determined whether the value falls within the area between V out V bat If it is smaller than +ΔV, it means that the voltage value is within the suitable range, and conversely, if it is larger than +ΔV, it means that the voltage value is not within the suitable range.

[0053] In the graph shown in Figure 4, the output voltage V out The value V0 of "V bat If the resistance is below the "+ΔV" value, this control method can exclude V0. This is because if the resistance falls between the "two thresholds," further decreasing the resistance from this state (-ΔR) will move it to V0, so in this case control is performed to increase the resistance (+ΔR).

[0054] As described above, in the flowchart of Figure 5, because continuous control is performed, the voltage value cannot remain at V1 permanently, but will mainly fluctuate between V1 and V2. In other words, as a result of applying MCPT control, the voltage will ultimately "oscillate around the optimal value," achieving the ideal state for this control.

[0055] In this way, by repeating the above steps S203, S204, S205 and S206, even if the position of the power supply target changes and the distance d between the power transmitting device 10 and the power receiving device 1 changes (see (A) of Figure 1), the magnitude of the resistance is adjusted by VCR 30, so it is possible to ensure that the desired current value I1 is always obtained.

[0056] "Component elements of MCPT" Hereinafter, the means for carrying out each flow in FIG. 5 will be specifically described with reference to FIGS. The configurations shown in FIGS. 6 to 10 are merely examples, and the present embodiment is not limited to the configurations shown in these figures.

[0057] FIG. 6 is a diagram illustrating a circuit 300 that implements step S203 of FIG. That is, in the figure, in step S203, the output current I out is the predetermined maximum value I bat_max "I out bat_max As shown in the figure, the circuit 300 is configured using linear current dependent voltage sources 310 and 320 and a comparator 330, and is out " and "I bat_max Step S203 may be configured by comparing ".

[0058] Current-controlled voltage sources 310 and 320 are elements that output a voltage proportional to the detected current value. Therefore, the current I out ​By inputting the current I out Voltage V(I out ) can be output. Similarly, a current I is applied to the input terminal of the current-controlled voltage source 320. out_max By inputting the current I out Voltage V(I out_max ) can be output. I out_max The value of can be predetermined.

[0059] Comparator 330 is an element that compares two voltages or currents and switches its output depending on which is greater. In the illustrated example, the voltage V(I out ) and voltage V(I out_max ) are input to comparator 330, and the output is switched depending on which is larger. Voltage V(I out ) is the voltage V(I out_max ), the output of the comparator 330 will be the maximum positive voltage, and vice versa, the output will be the maximum negative voltage. Note that there may be cases where the input values ​​are exactly the same, but in that case, there is usually no technical problem. If this logic is yes, it outputs 1, and if it is no, it outputs 0. The same applies to the following explanations.

[0060] FIG. 7 is a diagram illustrating a circuit 400 that implements step S204 of FIG. That is, in the figure, the output voltage V out is the predetermined maximum value "V bat +ΔV" to determine whether it exceeds "V out >V bat As shown in the figure, the circuit 400 is configured using a voltage source 410 and a comparator 420, and V out and "V bat Step S204 may be configured by comparing the voltage Vcc with the reference voltage Vdc.+ΔV.

[0061] For example, the value of a voltage source acting as a constant voltage electric circuit is V bat A voltage source 410 is connected so that a predetermined voltage value ΔV is added to the output voltage V. out The value of is input directly to the comparator 420. These two values ​​are compared, and if the logic is yes, it outputs 1, and if it is no, it outputs 0. The same applies to the following explanations.

[0062] FIG. 8 is a diagram illustrating an example where the output logic of circuit 300 in FIG. 6 and the output logic of circuit 400 in FIG. 7 are implemented using a NAND logic 500. That is, this diagram illustrates a circuit that realizes a flow using the output logic of FIG. 6 and the output logic of FIG. 7, and in particular, uses a NAND logic 500. NAND 500 can be configured as the negation (NOT) of the result of a logical product (AND). Generally, the output is 0 only when all inputs are High, and the output is 1 when even one input is Low.

[0063] Normally, when the output of the first comparator 330 is 1 (yes) and the output of the second comparator 420 is 1 (yes), the NAND of the NAND 500 outputs 0 (no). Furthermore, when the output of the first comparator 330 is 1 (yes) and the output of the second comparator 420 is 0 (no), the NAND of the NAND 500 outputs 1 (yes). Furthermore, when the output of the first comparator 330 is 0 (no) and the output of the second comparator 420 is 1 (yes), the NAND of the NAND 500 outputs 1 (yes). Furthermore, when the output of the first comparator 330 is 0 (no) and the output of the second comparator 420 is 0 (no), the NAND of the NAND 500 outputs 1 (yes).

[0064] Using the above characteristics, the truth table for NAND 500 can be determined as follows: That is, when the output of the first comparator 330 is 1 (yes) and the output of the second comparator 420 is 1 (yes), the NAND of the NAND 500 outputs 0 (no). Furthermore, when the output of the first comparator 330 is 1 (yes) and the output of the second comparator 420 is 0 (no), the NAND of the NAND 500 outputs 1 (yes). Also, when the output of the first comparator 330 is 0 (no) and the output of the second comparator 420 is 1 (yes), the NAND of the NAND 500 can be ignored in this embodiment (see "don't care"). Furthermore, when the output of the first comparator 330 is 0 (no) and the output of the second comparator 420 is 0 (no), the NAND of the NAND 500 outputs 1 (yes).

[0065] In the above truth table, when 1 is output, the resistance value R out "R" which increases by a predetermined amount out In addition, in the above truth table, when 0 is output, the resistance value R out "R" out The value of ΔR can be determined in advance. It is possible to make corrections to the above truth table.

[0066] 9 and 10 are diagrams illustrating a circuit 600 that implements steps S205 and S206 of FIG. Referring to FIG. 9, the output of the NAND 500 in FIG. 8 is input to a digital counter 610. This counter 610 counts (counts up) the number of times 1 is input in the output logic of FIGS. 6 and 7. When 1 is input, R out Also, inputting 0 means that R outThe output of the counter 610 is configured to be sent to a D / R converter (Digital to Resistance converter) 620. It is possible to use a D / A converter (Digital to Analog Converter) instead of the D / R converter.

[0067] Referring to FIG. 10, the configuration shown in FIG. 9 is shown more specifically, and the D / R converter 620 has voltage-controlled resistors (see 641, 642, and 643). Counter 610 counts up each time 1 is input, and D / R converter 620 turns off one switch each time it counts up, thereby increasing the resistance value (see 641, 642, and 643). Preferably, the resistance value (see 641, 642, and 643) is increased in equal steps by a predetermined magnitude.

[0068] 10, a D / R converter 620 has a plurality of resistors 641, 642, and 643 connected in series, and is provided with switches 631, 632, and 643 that enable selection of each of the resistors 641, 642, and 643. The resistors 641, 642, and 643 are configured to have the same magnitude. The digital counter 610 in FIG. 10 is configured to close one of the switches 631, 632, and 633 each time a 1 is input. In other words, the more times 1 is input, the more times the switches 631, 632, and 633 are closed. Correspondingly, V out and V bat 4, this results in moving from the right side of the graph to the left side.

[0069] In this way, in circuit 600, switches 631, 632, and 643 are turned off one by one each time the counter is counted up, so that the values ​​of resistors 641, 642, and 643 change stepwise. While three resistors 641, 642, and 643 are connected in series in FIG. 10, the number, size, and arrangement of resistors 641, 642, and 643 can be varied in various ways depending on the embodiment. Furthermore, resistors 641, 642, and 643 do not necessarily all have the same value. For example, when control is started from the rightmost side in FIGS. 3 and 4, a relatively large resistor may be selected in the initial stage to increase the control speed.

[0070] As described above, this embodiment realizes MCPT control using the relatively simple flow illustrated in FIG. 5, using the simple components illustrated in FIGS. 6 to 10. By adopting this configuration, the use of complex components and flows can be avoided. In particular, MCPT control is realized without using expensive devices that consume high power consumption, such as memory (storage device) or CPU (microcomputer). As a result, MCPT control can be performed to obtain a generally optimal operating point with a relatively simple implementation. While this control does not necessarily guarantee that the system will operate at the most efficient operating point, this embodiment is superior in that it can derive an optimal operating point with low power consumption.

[0071] In the above-described MCPT control, the resistance value is first maximized, and then the resistance value is gradually reduced, and the voltage value is compared with a predetermined threshold value to determine whether the corresponding current value is suitable (see Figures 4 and 5). This embodiment is not limited to the flow shown in FIG. 5. Various modifications can be made to this flow. For example, as described above, the resistance value does not necessarily have to be maximized in the initial setting of MCPT control. For example, the resistance value may be set to the intermediate value of the resistance on the horizontal axis of the graph shown in FIG. 3, or any value between the maximum value and the intermediate value.

[0072] Referring to FIG. 11, in the modified example of MCPT control, the voltage value is compared with two predetermined threshold values ​​(see the two horizontal thick lines in FIGS. 3 and 4), and the voltage value V OUT is a given upper limit (V bat +ΔV) and lower limit (V bat ) and whether it is within the range. That is, although the current value is maximized, it is not desirable to deviate from the lower limit standard of the voltage required for the storage device. For this reason, VCR 30 goes through steps S303 and S304 to reduce the output voltage V out is the predetermined maximum value "V bat +ΔV” and the predetermined threshold V bat It may be determined that the difference is greater than .

[0073] In FIG. 11, the VCR 30 makes the following determination. V bat <V out <V bat +ΔV For example, suppose that a state indicated by symbol V0 occurs under some condition. That is, in the determination of step 304, the output voltage V out is the predetermined maximum value "V bat +ΔV” and the output voltage V out is a predetermined threshold V bat It is assumed that the value is determined to be below . In this case, the VCR 30 then performs control to increase the resistance value by a predetermined amount ΔR in step S307. out =R out +ΔR”. 4, for example, in the state of V0, the resistance increases by R0, and V0 is increased to V1. As a result, the VCR 30 increases the output voltage V out is the predetermined maximum value "V bat +ΔV” and the predetermined threshold V bat It may be determined that the difference is greater than .

[0074] In the flowchart shown in FIG. 11, as in S304 and S306, out The value of V bat and Vbat +ΔV and the threshold value of V. However, the flowchart shown in Figure 5 also includes this technical idea. out > V bat Even if +ΔV is not, V out > V bat This is because ΔV is set so as to satisfy the above. Therefore, when comparing Fig. 5 and Fig. 11, the flow shown in Fig. 5 is more suitable from the viewpoint of configuring the flow more compactly and minimizing the number of required components. However, in the case of Fig. 11, there is a possibility that unnecessary operations can be reduced. In addition, depending on the embodiment, modifications can be made to the flow shown in Fig. 5. For example, the start and end conditions can be set in more detail (for example, by referring to the time, etc.). [Example]

[0075] "Example of changing power receiving device 1" Although the power receiving device 1 has been described above with reference to Fig. 1 to Fig. 11, the configuration of the power receiving device 1 is not limited to the example shown in Fig. 1. Below, modified examples of the power receiving device 1 shown in Fig. 1 will be described with reference to Fig. 12 to Fig. 16. FIG. 12(A) shows a simplified version of the power receiving device 1 of FIG. 1(B), showing that the output of the rectenna 20 is sent to the MCPT controller 30, and then supplied to the battery 40. 12(B) shows a modification of the power receiving device 1 shown in FIG. 12(A). As shown in the figure, the output of the rectenna 20 may be connected to a buck converter or step-down converter 50 in the upstream stage of the MCPT controller 30. The buck converter 50 may be a DC-DC converter that obtains an output at a voltage lower than the input voltage. The output step-down converted by the buck converter 50 may be supplied to the MCPT controller 30.

[0076] Referring to Figure 12(C), a modification of the system illustrated in Figure 12(A) is shown. As shown in the figure, the output of the rectenna 20 may be connected to a boost converter or step-up converter 60 in the preceding stage of the MCPT controller 30. The boost converter 60 may be a DC-DC converter that obtains an output at a voltage higher than the input voltage. The output that has been step-up converted by the boost converter 60 may be supplied to the MCPT controller 30.

[0077] As an alternative to the examples shown in FIG. 12(B) or (C), the output of rectenna 20 may be connected to a buck-boost converter, which has the functions of both a boost converter and a buck converter, in the upstream stage of MCPT controller 30. In this case, the buck converter and the boost converter may be connected in parallel. The buck-boost converter may also be a single component. For example, the circuit configurations shown in FIG. 13 or FIG. 14 may be employed.

[0078] 13 shows an example in which the output of rectenna 20 is connected in parallel to buck converter 50 and boost converter 60 in the upstream stage of MCPT controller 30. This circuit can function as a buck-boost converter in which either the function of buck converter 50 or boost converter 60 can be selected by a switch, and the boost-converted or buck-converted output can be supplied to MCPT controller 30. For example, when only the switch SW2 is turned on, only the function of the buck converter 50 may be selectively applied, and when only the switch SW3 is turned on, only the function of the boost converter 60 may be selectively applied.

[0079] Furthermore, when only switch SW1 is turned on, the functions of both buck converter 50 and boost converter 60 may be avoided. That is, since the efficiency of a converter is generally 90% or less, it may be possible to switch between using and not using the converter, taking this efficiency into consideration. 13, the MCPT controller 30 monitors the output voltage of the rectenna 20 and regulates the desired voltage V out If the two are equal, only the switch SW1 is turned on, if they are larger, only the switch SW2 is turned on, and if they are smaller, only the switch SW3 is turned on. This control is performed by feedforward.

[0080] FIG. 14 is a diagram showing a modification in which a buck-boost converter is added to the power receiving device. Referring to FIG. 14, the buck-boost converter 65 is configured as the same circuit (configured as one device), and switches SW4 and SW5 make it possible to switch between a case where the buck-boost converter 65 is used and a case where the buck-boost converter 65 is not used.

[0081] For example, the MCPT controller 30 monitors the output voltage of the rectenna 20 (the output of the rectifier 24) and adjusts that value to the desired voltage V out As a result, the output voltage of rectenna 20 and V out If it is determined that the voltage difference between the output voltage of the rectenna 20 and V is large, the switch SW5 may be turned on to selectively use the buck-boost converter 65. out If it is determined that the voltage difference between the buck-boost converter 65 and the buck-boost converter 65 is small, the switch SW4 may be turned on to selectively disable the buck-boost converter 65. This control is performed by feedforward.

[0082] In this way, the buck converter (step-down DC-DC converter) does not need to function all the time. As described above, the output of the rectenna 20 may be selectively connected to the buck converter (DCDC) 50 using a switch in the MCPT controller 30. In particular, since the use of a DCDC can cause an impedance mismatch and reduce efficiency, the DCDC may be selectively used by operating the switch only when it is necessary to increase the voltage.

[0083] The MCPT controller 30 also monitors the output voltage of the rectenna 20 (the output of the rectifier 24) and adjusts the value to the desired voltage V out As a result, if it is determined that the output voltage of the rectenna 20 is low, the switch may be turned on to selectively use only the boost converter 60. Also, if it is determined that the output voltage of the rectenna 20 is high, the switch may be turned on to selectively use only the buck converter 50. Furthermore, if the output voltage of the rectenna is V out If it is determined that the two converters are equivalent, the switch may be turned on to select a state in which neither the boost converter 60 nor the buck converter 50 is selected.

[0084] The effect of adding a buck converter 50 and / or a boost converter 60 will be described with reference to FIG. 15 . As can be seen from the output diagram of the buck converter (step-down DC-DC converter) 50 illustrated in FIG. 15 , the use of the buck converter 50 does not increase the maximum output power. However, by using the buck converter 50, it is possible to lower the voltage while maintaining the power, which is the product of voltage and current, constant. In other words, a change in the relationship between "decreasing the voltage value from high to low," "increasing the current value from low to high," and "maintaining constant power" can be achieved. That is, even with the same resistance value (horizontal axis) in the graph of FIG. 15 , adding the buck converter 50 and / or the boost converter 60 can increase the current value. In this case, referring to FIG. 15 , it can be seen that the current value is shifted horizontally. Therefore, adding the buck converter 50 and / or the boost converter 60 to the power receiving device 1 has the effect of increasing the current value with the same resistance value compared to when not using the buck converter 50 and / or the boost converter 60. Applying the flow of FIG. 5 to this configuration of the power receiving device 1 can achieve the desired current maximization effect.

[0085] FIG. 16 is a diagram showing a modified example in which an LDO (Low Drop-Out regulator) 70 is added to the power receiving device. Referring to FIG. 16, in another embodiment, the output of the rectenna 20 may be connected to an LDO 70 before the MCPT controller. The LDO 70 is also known as a low-dropout regulator. It is a series regulator that can operate with a very small difference between the input voltage and the output voltage. The output converted by the LDO 70 may be supplied to the MCPT controller 30. Using the LDO 70 allows for better voltage regulation (and corresponding current regulation) than would be possible without the LDO 70.

[0086] Although modifications of the power receiving device 1 illustrated in FIG. 1 have been described above with reference to FIGS. 12 to 16, modifications of the power receiving device 1 are not limited to these. For example, in other embodiments, the output of rectenna 20 may be connected to a buck converter 50, a boost converter 60, or a buck-boost converter 65 (not shown) after MCPT controller 30. Additionally, in other embodiments, the output of rectenna 20 may be connected to an LDO 70 (not shown) after MCPT controller 30.

[0087] "Feedback control of MCPT" 1 and 12 to 16. For example, as shown in FIG. 17, the power receiving device 1 may include a transmitter 80 that transmits a feedback signal to the power transmitting device 10.

[0088] In this embodiment, the MCPT controller 30 controls the voltage value (V bat ) is observed. The value may be transmitted to a data receiver 8 on the power transmitting device 10 side via a data transmitter 80 on the power receiving device 1 side. At this time, the frequency of data transmission can be adjusted depending on the power receiving state of the power receiving device 1. For example, V batIf the value of V is large, there is a margin of power on the power receiving device 1 side, so the MCPT controller 30 may transmit data from the transmitter 80 to the receiver 8 at a high frequency. This can improve the reliability of data communication between the power transmitting device 10 and the power receiving device 1. On the other hand, bat If the value of is small, there is no power margin on the power receiving device 1 side, so the MCPT controller 30 may transmit data from the transmitter 80 to the receiver 8 at a low frequency. This allows the power consumption of the power receiving device 1 as a whole to be reduced.

[0089] In particular, in the field of FA, when the power receiving device 1 is installed in a place where its position is constantly changing, such as a robot hand unit 120 or a robot arm unit 110 (see FIG. 1), it is necessary to obtain accurate data. As described above, in this embodiment, the MCPT controller 30 always controls V bat Therefore, the "V bat <V out <V bat +ΔV". Therefore, in this embodiment, the reliability of the data is improved and traceability is ensured. For example, when the relative distance d between the power transmitting device 10 and the power receiving device 1 changes, the change in the power transmission status can be tracked with high frequency.

[0090] As described above, the transmission frequency of the transmitter 80 can be changed depending on the power receiving condition of the power receiving device 1. For example, when the power receiving condition is good, the transmitter 80 may transmit at a frequency of 1 ms. When the power receiving condition is not good, the transmitter 80 may transmit at a frequency of 5 ms. Since the power receiving device 1 consumes power for the data transmission itself by the transmitter 80, when the power receiving condition deteriorates, the power consumption of the entire system can be reduced by transmitting data at a lower frequency. Conversely, when the power receiving condition is sufficient, transmission can be performed at a higher frequency, thereby improving traceability.

[0091] Furthermore, as illustrated in FIG. 18, the power receiving device 1 may transmit a feedback signal to the power transmitting device 10 to perform other controls. As described above, in this embodiment, the MCPT controller 30 controls V bat Observe V bat If the value of is too large, it may happen that the power storage device 40 of the power receiving device 1 is overcharged. In this case, the MCPT controller 30 may transmit a feedback signal to the power transmitting device 10 to perform control to stop transmission of the power transmitting device 10 (or reduce the magnitude of the transmission energy), thereby reducing power consumption in the entire system. On the other hand, V bat If the value of is too small, the power storage device 40 of the power receiving device 1 may be over-discharged. In this case, the MCPT controller 30 may transmit a feedback signal to the power transmitting device 10 to increase the transmission of the power transmitting device 10 (or increase the magnitude of the transmission energy).

[0092] The power transmitting device 10 transmits energy E to the power receiving device 1 via a power transmitting antenna 12 (see FIG. 1), but it is possible to use a plurality of power transmitting antennas 12. In this case, for example, when a single power transmitting antenna 12 cannot transmit a sufficient amount of energy E, the power transmitting device 10 may perform control to simultaneously transmit energy E from a plurality of power transmitting antennas 12. Note that the number of power transmitting antennas 12 may be any number equal to or greater than two.

[0093] The lifespan of the power storage device 40 may be shortened by over-discharging / over-charging. Therefore, by transmitting a feedback signal according to the power receiving state of the power receiving device 1 to the power transmitting device 10 and controlling the power transmitting antenna 12, it is possible to avoid incurring adverse damage to the power storage device 40 and to extend the lifespan of the power storage device 40. Furthermore, heat (i.e., operating time) can shorten the lifespan of the power transmitting device 10. Therefore, by transmitting a feedback signal according to the power receiving state of the power receiving device 1 to the power transmitting device 10 and performing control to adjust the transmission state of the power transmitting antenna 12 so that it does not always output high power, it is possible to extend the lifespan of the power transmitting device 10. Therefore, by performing the above control, this embodiment can extend the lifespan of both the power transmitting device 10 and the power receiving device 1. Therefore, when this embodiment is applied to the field of factory automation in particular, it can contribute to solving the problem of extending the lifespan that is specific to factory automation. [Example]

[0094] As described above, in the first and second embodiments, the MCPT controller 30 of the power receiving device 1 is configured to perform low-power consumption control. In particular, the MCPT controller 30 is configured to perform MCPT control without using a memory or a CPU. This contributes to significantly reducing the power consumption of the entire power receiving device 1. This effect is particularly suitable when wireless power is supplied using a microwave system that has an upper limit on the amount of energy that can be transmitted. 19 to 21, the MCPT controller 200 of the power receiving device 1A is configured to perform control using a memory 240 and a CPU 260. In this case, the power consumption of the entire power receiving device 1A is increased, but more advanced control can be performed. When the conditions for the transmittable energy capacity are met, the third embodiment can be applied.

[0095] 19, there is shown a schematic diagram of components of the MCPT controller 200 of the power receiving device 1 A. As shown in the figure, the MCPT controller 200 includes a CPU (processor) 260 and a memory (storage device) 240. The CPU 260 is generally defined as a device that executes software (programs). For example, the CPU 260 is a von Neumann-type CPU. The CPU 260 may include a control device that controls the entire system, an arithmetic unit, a register that temporarily stores data, an interface with the memory 240, and an interface with input / output devices for peripheral devices. The memory 240 is defined as a device capable of storing data. For example, the memory 240 may be a primary storage device directly accessible by the CPU 260 or a secondary storage device accessed using an input / output channel, etc. For example, the memory 240 may be any media, such as a fixed disk, a volatile or non-volatile random access memory, a CD, a DVD, a flash drive, a removable medium (e.g., a thumb-sized miniature memory) attached to a corresponding interface (e.g., a USB port), or the like.

[0096] The CPU 260 processes information by sequentially reading, interpreting, and executing a sequence of instructions called a program stored in the memory 240. For example, the CPU 260 can perform various calculations based on various values ​​such as the voltage and resistance values ​​flowing through the circuit of the power receiving device 1A. For example, based on the fact that the resistance R, current I, and voltage V can be expressed as Ohm's law (V=I×R), when two of these three values ​​are obtained, the CPU 260 may calculate the value of the remaining one. For example, the CPU 260 may calculate the output voltage V of the rectenna 20. out and the value of resistor 210 on the output side of rectenna 20 can be obtained. Therefore, CPU 260 may calculate current value I based on voltage value V and resistance value R, as indicated by reference numeral 230 "V to I (calculate current value from voltage value)." This calculated value can be stored in memory 240 connected to CPU 260.

[0097] In addition to the above programs, memory 240 stores various databases (DBs) such as table 270 (see FIGS. 20 and 21). A "database" is a functional element (storage unit) that stores a set of data so that it can accommodate any data manipulation (e.g., extraction, addition, deletion, overwriting, etc.) from a processor or an external computer. The method of implementing the database is not limited, and may be, for example, a database management system, spreadsheet software, or a text file such as XML or JSON. Hereinafter, a set of data stored in memory 240 will be simply referred to as a table.

[0098] As described above, the CPU 260 can store any calculated value in the memory 240. Furthermore, the CPU 260 can call up the value stored in the memory 240 at any timing. For example, as indicated by the reference numeral 250 "comparator," the CPU 260 can compare the calculated current value I with the immediately previous value (the value one step before, I out_tmp ) and the currently calculated value (current step value, I out ) may be compared. Based on the result, the CPU 260 can perform control for the next step (value one step later).

[0099] For example, the CPU 260 may control ΔR (change in resistance) as shown by reference numeral 220 based on the output of the comparator 250, as shown in FIGS. 3 and 4. This allows the current I bat The voltage value V sent to the power storage device 40 is appropriately changed. bat may be adjusted.

[0100] The CPU 260 calculates the current value I by subtracting the value I from the previous step. out_tmp and the value of the current step I out The control of ΔR (change in resistance) may be changed based on the difference between the difference and the difference. For example, when the difference is large, the CPU 260 may control ΔR (change in resistance) at a relatively large rate. When the difference is small, the CPU 260 may control ΔR (change in resistance) at a relatively small rate.

[0101] The comparison calculation performed by the CPU 260 is not limited to the above example. For example, as indicated by the reference numeral 250 "comparator," the CPU 260 may perform a comparison calculation of the calculated current value I between a past value (the value one step ago, the value two steps ago, or the value three or more steps ago) stored in the memory 240 and the current value (the value of the current step). Based on the result of the comparison calculation, the CPU 260 may adjust the value of ΔR (change in resistance) so as to perform control for the next step (the value one step later, the value two steps later, or the value three or more steps later).

[0102] In fields such as factory automation, when a power receiving device 1A (see power receiving device 1 in Figure 1) is installed inside a moving part such as a robot hand unit 120 or a robot arm unit 110, the distance d between the power transmitting device 10 and the power receiving device 1A changes, and the power receiving situation also changes accordingly. In MCPT control, it can be assumed that the optimal resistance value ΔR is roughly determined depending on the distance d. That is, in fields such as factory automation, the operating range of moving parts can be known in advance. For each value of the distance d that depends on the change, the change in the optimal resistance value ΔR can also be known in advance.

[0103] In particular, CPU 260 performs control to change resistance value ΔR based on information about distance d. At this time, the above-mentioned table 270 (see FIGS. 20 and 21) can be created in advance for values ​​such as ΔR according to changes in various conditions and stored in memory 240. Then, CPU 260 may refer to table 270 stored in memory 240 when performing control to change ΔR. 20 and 21 are diagrams illustrating an example of a power receiving device that performs MCPT control using a table 270 stored in the memory 240. As illustrated in the diagrams, the change in the distance d and the voltage value V of the power storage device bat The changes in resistance ΔR and the corresponding changes in resistance ΔR can be compiled in advance into a table and stored in the memory 240.

[0104] For example, referring to Table 270, the voltage value V of the power storage device 40 is batWhen the voltage is 3V and the distance d is 1m, a resistance of 1kΩ is preferable. Also, when the distance d changes from this state to 2m, the voltage of 3V V bat A resistance of 1.5 kΩ is preferably associated with the voltage value V bat When the voltage is 3.2V and the distance d is 1m, a resistance of 2kΩ is preferable. Also, when the distance d changes from this state to 2m, the V bat A resistance of 2.5 kΩ is preferably associated with

[0105] In this way, the change in the distance d and the voltage value V of the storage device 40 bat Suitable resistance values ​​corresponding to the change in the distance d and the voltage value V of the power storage device 40 can be compiled in a table 270 and stored in the memory 240. These values ​​can be determined by actual measurement (hardware) depending on the individual embodiment. Alternatively, these values ​​can be determined by simulation (software). Alternatively, these values ​​can be determined by a combination of hardware and software. The values ​​constituting the table are the distance d, the voltage value V of the power storage device 40, and the voltage value V of the power storage device 40. bat , resistance values. In addition, the number of tables is not limited to one, but multiple tables can be prepared depending on the embodiment, and the CPU 260 can select an appropriate one from among them.

[0106] Therefore, the CPU 260 of the MCPT controller 200 stores information about the distance d as table 270 in the memory 240, and can select an appropriate resistance value from the pre-prepared table 270 according to the value of the distance d, etc. As a result, if the currently used resistance value is far from the appropriate value corresponding to the distance d, the CPU 260 can change the resistance value to an appropriate value. Therefore, even if the distance d between the power transmitting device 10 and the power receiving device 1 changes, the CPU can perform optimization control to always bring the resistance value close to the optimal value.

[0107] This control is not limited to the resistance value currently required, and may be applied to a value predicted to be required in the future, one step later or two or more steps later. For example, when the power receiving device 1A (see the power receiving device 1 in FIG. 1) is installed in a moving part such as the robot hand unit 120 or the robot arm unit 110, the future movement of the machine 100 can be predicted, and therefore, based on this prediction, changes in resistance may be predicted in advance not only for the current state but also for the state one step later or two or more steps later.

[0108] Based on the table 270, the CPU 260 may calculate values ​​that cannot be obtained directly from the table 270. For example, the CPU 260 may obtain necessary values ​​based on the values ​​in the table 270 by interpolation or extrapolation. For example, when information between two consecutive points M1 and M2 is required, information between the two points may be obtained (interpolated) based on the information about these two points. For example, when the resistance value at a distance d of 1.5 m for 3 V is required, the CPU 260 may obtain a value of 1.25 kΩ by interpolating two values: a resistance value of 1 kΩ at a distance d of 1 m for 3 V, and a resistance value of 1.5 kΩ at a distance d of 2 m. Furthermore, when information outside two consecutive points M1 and M2 is required, information on the extension of the two points may be obtained based on the information on these two points (extrapolation). For example, when the resistance value at a distance d of 2.5 m for 3 V is required, the CPU 260 may obtain a value of 1.75 kΩ by extrapolating two values: a resistance value of 1 kΩ at a distance d of 1 m for 3 V, and a resistance value of 1.5 kΩ at a distance d of 2 m.

[0109] In this way, CPU 260 may obtain necessary information by calculation based on table 270. Note that CPU 260 is not limited to obtaining an average value when performing interpolation or extrapolation calculations. For example, if a value suddenly increases or decreases under certain circumstances, CPU 260 may obtain a value corresponding to the change, rather than obtaining an average value from the values ​​in table 270. For example, data such as statistical values ​​(variance, standard deviation, function, etc.) may be associated with table 270 to describe the change.

[0110] Preferably, the MCPT controller 200 controls the voltage value V OUT The distance d between the power transmitting device 10 and the power receiving device 1A can be determined by several methods. Therefore, the CPU 260 can select an optimum resistance value based on these values. FIG. 20 shows the power receiving device 1A side receiving power V out 10 is a diagram illustrating a case where the distance d is calculated based on the received power V out However, in general, the distance d is proportional to the received power V out For example, the measured received power V out If V is relatively large, the CPU 260 can infer that the distance d is relatively small. out If V is relatively small, the CPU 260 can infer that the distance d is relatively large. out The correspondence between the distance d and the voltage V can be measured or calculated in detail in advance depending on the embodiment. out Based on this, data relating to the distance d between the power transmitting device 10 and the power receiving device 1A can be calculated. The MCPT controller 200 selects an optimum resistance value based on the information on the distance d calculated by the CPU 260.

[0111] FIG. 21 illustrates a case where the power receiving device 1A receives data on the distance d determined by the power transmitting device 10. As shown in FIG. 21, on the host side that transmits energy E, the power transmitting device 10 can determine the distance d between the power transmitting device 10 and the power receiving device 1A based on the power transmission state. For example, in the case of the robot hand illustrated in FIG. 1, the host side controls the position of the device side, so the distance d between the host and the device can be determined. The power transmitting device 10 can transmit the data on the distance d via the data receiver 9. On the device side, the power receiving device 1A includes a data receiver 90. When the data on the distance d is transmitted from the data receiver 90, the data can be transmitted to the CPU 260. Therefore, the CPU 260 can receive data on the distance d between the power transmitting device 10 and the power receiving device 1A from the power transmitting device 10. The MCPT controller 200 selects an optimal resistance value based on the information on the distance d transmitted from the data transmitter 9.

[0112] In this way, on the power receiving device 1A side, the CPU 260 receives the received power V out The distance d may be determined by measuring the distance d (see FIG. 20). Alternatively, the power transmitting device 10 may determine the position of the power receiving device 1A, and the CPU 260 may determine the distance d based on data transmitted from the power transmitting device 10 (see FIG. 21). Note that there is no need for the power receiving device 1A to feed back the control result to the power transmitting device 10.

[0113] As described above, in the power receiving device 1A of the third embodiment illustrated in FIGS. 19 to 21, various components can be added, like the power receiving device 1 of the second embodiment illustrated in FIGS. Furthermore, the present invention can provide a computer program product that enables the MCPT control described above to be performed on the MCPT controller 200 of the power receiving device 1A illustrated in FIGS.

[0114] The computer program product may be implemented as a program, a feature, a function, a routine, or an executable object. Preferably, the computer program product comprises program code for enabling the MCPT control. Therefore, another aspect of the present invention relates to a computer program product for performing the above control when used on the MCPT controller 200 in the power receiving device 1A.

[0115] A computer program product, such as a computer program means, may be embodied on a memory card, a USB stick, a CD-ROM, a DVD or as a file downloadable from a server in a network, for example such a file may be provided by transferring the file comprising the computer program product over a wireless communication network.

[0116] Those skilled in the art will be able to make various adaptations and modifications to the above embodiments without departing from the scope of the claims. For example, each of the parts (components) of the power receiving device 1 or 1A may include other components necessary for its operation and may further include additional components to provide functionality other than those described herein. It is therefore to be understood that the claims may be practiced otherwise than as specifically described herein. [Explanation of symbols]

[0117] 1, 1A powered device 10 Power transmission equipment 20 Rectenna (receiving antenna) 22 Receiving antenna section 24 Rectifier 30, 200 Controller (Voltage Control Resistor or MCPT Controller) 40 Electrical storage device (battery or capacitor) 50 Buck Converter 60 Boost Converter 65 Buck-Boost Converter 70 LDO 80 Data Transmitter 90 Data Receiver

Claims

1. A power receiving device that receives power transmitted from a power transmitting device based on a microwave wireless power feeding system, a receiving antenna for receiving microwaves; a rectifier operatively connected to the receiving antenna for converting the microwaves into a DC voltage; a controller operatively connected to the rectifier for adjusting a resistance on an output side of the rectifier; a power storage device that stores an output of the controller, the voltage-current characteristics of the rectifier change depending on the distance between the power transmitting device and the power receiving device; The controller performs maximum current point tracking (MCPT) by changing a resistance value so that a voltage value on the output side of the rectifier falls below a predetermined threshold value.

2. The power receiving device according to claim 1, wherein the power receiving device performs the maximum current point tracking control (MCPT) by gradually changing a resistance value so that the voltage value on the output side of the rectifier falls below a predetermined threshold without using a CPU and a memory.

3. The controller means for setting the resistance value to an initial value; means for determining whether the current value exceeds a threshold; means for determining whether a voltage value exceeds a threshold value; means for gradually changing the resistance value when the voltage value exceeds a threshold value; The power receiving device according to claim 1 or 2, wherein the controller repeats the determination of the current value, the determination of the voltage value, and the stepwise change of the resistance until a desired current value is obtained.

4. The power receiving device according to claim 3 , wherein the means for determining whether the current value exceeds the threshold value is configured using a current-controlled voltage source and a comparator.

5. The power receiving device according to claim 3 , wherein the means for determining whether the voltage value exceeds the threshold value is configured using a voltage source and a comparator.

6. 4. The power receiving device according to claim 3, wherein the means for changing the resistance value stepwise when the voltage value exceeds the threshold value is configured using a negative logical product and a counter.

7. The power receiving device according to claim 3 , wherein the means for changing the resistance value stepwise when the voltage value exceeds the threshold value is configured using a plurality of resistors and a plurality of switches.

8. A power receiving device that receives power transmitted from a power transmitting device based on a microwave wireless power feeding system, a receiving antenna for receiving microwaves; a rectifier operatively connected to the receiving antenna for converting the microwaves into a DC voltage; a controller operatively connected to the rectifier for adjusting a resistance on an output side of the rectifier; a power storage device that stores an output of the controller, the voltage-current characteristics of the rectifier change depending on the distance between the power transmitting device and the power receiving device; the controller includes a CPU and a memory; a table storing a correspondence between a distance between the power transmitting device and the power receiving device, a voltage value of the power storage device, and a resistance value on an output side of the rectifier; The CPU acquires data regarding the distance between the power transmitting device and the power receiving device, and performs maximum current point tracking control (MCPT) by adjusting the resistance on the output side of the rectifier using the table stored in the memory.

9. The power receiving device according to claim 8 , wherein the controller receives data relating to a distance between the power transmitting device and the power receiving device from the power transmitting device.

10. The power receiving device according to claim 8 , wherein the controller calculates data relating to a distance between the power transmitting device and the power receiving device based on a voltage value on the output side of the rectifier.

11. The power receiving device according to claim 8, wherein the CPU calculates the current from the voltage value and resistance value on the output side of the rectifier, and determines the control for the next step by comparing the value of the previous step with the value of the current step stored in the memory.

12. The controller observes a voltage value of the power storage device, When a voltage value of the power storage device exceeds a predetermined threshold, an instruction to the power transmission device to reduce transmission power is transmitted; When the voltage value of the power storage device falls below a predetermined threshold, an instruction to increase the transmitted power is transmitted to the power transmission device. The power receiving device according to claim 8 .

13. 13. The power receiving device according to claim 1, further comprising at least one of a buck converter, a boost converter, and a buck-boost converter between the rectifier and the controller or between the controller and the power storage device.

14. The power receiving device according to claim 1 , further comprising a low-dropout regulator (LDO) between the rectifier and the controller or between the controller and the power storage device.

15. A power receiving method in which power transmitted from a power transmitting device is received by a power receiving device based on a microwave wireless power feeding system, the method comprising: The receiving antenna receives the microwaves, a rectifier operatively connected to the receiving antenna to convert the microwaves into a DC voltage; a controller operatively connected to the rectifier for adjusting a resistance on an output side of the rectifier; a power storage device that stores the output of the controller; the voltage-current characteristics of the rectifier change depending on the distance between the power transmitting device and the power receiving device; The power receiving method, wherein the controller performs maximum current point tracking (MCPT) by changing a resistance value so that the voltage value on the output side of the rectifier falls below a predetermined threshold.

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