Power receiving device

Abstract

To provide a concrete method with realizability and effectiveness for performing control of a MCPT with a relatively simple arrangement.SOLUTION: A power reception device that receives electric power transmitted from a power transmission device on the basis of a wireless power supply scheme, comprises: a power reception antenna that receives an electromagnetic wave; a rectifier that converts the electromagnetic wave into a DC voltage; a controller that adjust a resistance on an output side of the rectifier; and a power storage device that stores an output of the controller. Voltage current characteristics of the rectifier change in accordance with a distance between the power transmission device and the power reception device. The controller performs maximum current point tracking control by stepwise changing a resistance value so that a voltage value on the output side of the rectifier is lower than a predetermined threshold value.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Previously, Maximum Power Point Tracking (MPPT) or Maximum Current Point Tracking (MCPT) methods, which determine the optimal operating point by changing the voltage and current values ​​by changing the resistance value during power supply, have been known.

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

[0004] Referring to Figure 22(B), in the circuit of 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 power value of the solar cell. The output power of a solar cell changes depending on the resistance value, and it usually shows a bell-shaped graph. Control that makes the output of a solar cell follow the maximum power point (current × voltage value), i.e., the optimal operating point, when generating electricity is called Maximum Power Point Tracking (MPPT).

[0005] As illustrated in Figure 22(B), controlling the system to the optimal operating point where power is maximized based on a bell-shaped graph is also called the Hill Climbing Method. In this control, for example, the apparent resistance value connected to the output terminal of the solar cell may be changed by adjusting the on / off ratio of the circuit switching. The optimal operating point of a solar cell varies depending on the installation location and weather, but by applying MPPT, it is possible to change the resistance value as appropriate (see symbols R1, R2, R3) to obtain the maximum output (see symbols W1, W2, W3).

[0006] As background technology for this field, there is Japanese Patent Publication No. 2020-137304 (Patent Document 1). This publication states that "the objective is to provide a power system that makes it easy to extract a large amount of power from a fuel cell power generation system to a DC power converter by performing MPPT control using a DC power converter designed to perform MPPT control of a solar power generation system. In particular, characteristic conversion control is a control that makes the electrical output characteristics of the characteristic conversion circuit 100 follow reference table data. The electrical output characteristics represented by the reference table data are such that the output power is maximized when the output voltage is at a certain value within a predetermined range, and the output current decreases as the output voltage increases in the region where the output voltage crosses the above-mentioned value." (See abstract). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-137304 [Overview of the project] [Problems that the invention aims to solve]

[0008] Generally, MPPT control methods seek the maximum value of the power graph, which is shaped like a bell. However, since the current graph does not appear as a bell, even if the maximum power value is obtained based on MPPT, this does not mean that the maximum current value is obtained. When MCPT is used instead of MPPT, or in addition to MPPT, a relatively complex algorithm may be required. However, when the power capacity during power supply is limited, the increased power consumption required for the control itself may reduce the overall efficiency of the system.

[0009] Therefore, the present invention has a relatively simple configuration. circuit This provides a feasible, effective, and concrete method for controlling [the system]. [Means for solving the problem]

[0010] To solve the above problems, for example, adopt the configuration described in the claims. 。 [Effects of the Invention]

[0011] This invention has a relatively simple configuration. circuit This provides a feasible, effective, and concrete method for controlling [the system]. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic diagram illustrating an example of a power receiving device. [Figure 2] Figure 2 illustrates the output of the rectifier side of the rectenna in the power receiving device using three graphs. [Figure 3] Figure 3 is a graph illustrating an example of MCPT control application. [Figure 4] Figure 4 is an enlarged view of the main part of Figure 3. [Figure 5] Figure 5 is an example of the process flow for MCPT control. [Figure 6] Figure 6 is an example of a circuit that implements step S203 in Figure 5. [Figure 7] Figure 7 is an example of a circuit that implements step S204 in Figure 5. [Figure 8] Figure 8 illustrates a circuit that implements the output logic of Figure 6 and the output logic of Figure 7 using a negative AND logic. [Figure 9] Figure 9 is an example of a circuit that implements steps S205 and S206 of Figure 5. [Figure 10] Figure 10 is an example of a circuit that implements steps S205 and S206 of Figure 5. [Figure 11] Figure 11 shows an example of a change in the process flow shown in Figure 5. [Figure 12] Figure 12 shows an example of a modification to the power receiving device, in which a buck converter or boost converter has been added. [Figure 13] Figure 13 shows an example of a modification in which a buck converter and a boost converter are connected in parallel to the power receiving device. [Figure 14] Figure 14 shows an example of a modification to the power receiving device, in which a buck-boost converter has been added. [Figure 15] Figure 15 is a graph illustrating the effects of adding a buck converter or boost converter to a power receiving device. [Figure 16] Figure 16 shows an example of a modification to the power receiving device in which an LDO (Low Displacement Unit) has been added. [Figure 17] Figure 17 shows a modified example in which a transmitter that sends a feedback signal to the power receiving device has been added. [Figure 18] Figure 18 shows a modified example in which a transmitter that sends a feedback signal to the power receiving device has been added. [Figure 19] Figure 19 illustrates a power receiving device using an MCPT controller equipped with memory and a CPU. [Figure 20] Figure 20 illustrates a case where the power receiving device calculates the distance based on the received power. [Figure 21]Figure 21 illustrates a case where the receiving device receives distance data obtained by the power transmission device. [Figure 22] Figure 22 is a schematic diagram showing a circuit for charging a secondary battery using a solar cell, along with graphs of the circuit's resistance and power. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Note that the embodiments described below are just one example of the present invention, and the content of the present invention should not be interpreted as being limited based on the following description. [Examples]

[0014] "Overall configuration of the power receiving device" Referring to Figure 1(A), an embodiment of a power receiving device 1 that receives energy E from a power transmission device (Power Tx) 10 is schematically illustrated. The power receiving device 1 can be applied to wirelessly supply power to power-consuming devices used in various machines 100 in fields such as factories (FA: Factory Automation), the Internet of Things (IoT), and home appliances.

[0015] The power receiving device 1 is applicable to a variety of applications. In the example shown in Figure 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 for various uses, such as gripping, lifting (picking), placing, assembling, painting, and welding workpieces or parts W. For example, the machine 100 is a highly articulated robot that performs movements with a high degree of freedom.

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

[0017] When wiring is required to power the devices built into the articulated robot 100, the movement of the robot's joints J1a, J1b, J2a, J2b, and J2c can cause problems such as strain on the wiring, wire breakage, or maintenance issues. Furthermore, in machines that perform highly flexible movements, such as the articulated robot 100, various components such as actuators are generally built into the machine, resulting in limited space for additional wiring.

[0018] The power receiving device 1 wirelessly receives energy E from the power transmitting device 10. Therefore, even if the device to be powered (such as a sensor) is built into the articulated robot 100 and its position changes frequently, the necessary power can be sent to the device from a distance, and the aforementioned wiring problems can be avoided. The power receiving device 1 is also called a power receiver or power receiving system, etc., but will be referred to as power receiving device 1 hereafter. The power transmitting device 10, which operates in conjunction with power receiving device 1, is also called a power transmitter or power transmitting system, etc., but will be referred to as power transmitting device 10 hereafter.

[0019] The power receiving device 1 can be applied to various machines 100 in any configuration. The power receiving device 1 does not need to house all its components within the fingers of the robot hand 120 as illustrated in Figure 1(A). In this case, relatively large and bulky parts may be made flexible and rolled up and stored within the finger space. Also, some parts may be placed in locations away from the fingers (for example, at the base of the fingers of the robot hand 120 or in a wider area nearby). Furthermore, some parts can protrude outside the machine 100 as needed.

[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 a factory line, such as proximity sensors and magnetic sensors. Furthermore, the power receiving device 1 may be installed in general building management to monitor the conditions of the office environment, such as temperature, humidity, and illuminance sensors.

[0021] Referring again to Figure 1(A), the power transmission device 10 is positioned at a suitable location outside the articulated robot 100 and wirelessly transmits energy E to the power receiving device 1. There are several types of wireless power transfer, but in this embodiment, a microwave method is preferably used to wirelessly transfer power between the power transmission device 10 and the power receiving device 1. The microwave method can transmit energy or power over relatively long distances. For example, when performing wireless power transfer using the microwave method, it is possible to transmit power with a capacity of about 1 to 10 mW over a distance of about 1 m.

[0022] Referring to Figure 1(B), the components of the power receiving device 1 are schematically illustrated. The power transmitting device 10 is controlled by a controller (not shown) and transmits energy E to the outside from the power transmitting antenna section 12. This energy E is received by the rectenna (receiving antenna) 20 of the power receiving device 1. The rectenna 20 includes a power receiving antenna section 22 configured to receive energy E from multiple directions, and a rectifier 24 functionally connected to the power receiving antenna section 22.

[0023] The receiving antenna section 22 can have any configuration. The receiving antenna section 22 can be configured in various ways, such as a dipole antenna, monopole antenna, slot antenna, tip antenna, or similar. The transmitting antenna section 12 and the receiving antenna section 22 are separated by a distance d. The amount of power that can be supplied from the transmitting device 10 to the receiver is attenuated inversely proportional to the square of the distance d, according to Friis's law.

[0024] The rectifier 24 is an element that has a rectifying effect, allowing current to flow in only one direction, and converts the RF (electromagnetic wave) received by the receiving antenna section 22 into DC (direct current voltage). The receiving antenna section 22 and the rectifier 24 may be configured as an integrated unit. In this way, the rectenna 20 rectifies and converts microwaves into direct current.

[0025] The voltage output from the rectenna 20 is adjusted (V) after being controlled by a controller or voltage-controlled resistor (VCR) 30. out V bat (Adjust to the output V) bat The current is supplied to the energy storage device 40. At that time, the current value I is adjusted in response to the change in voltage value. bat Adjustments will also be made regarding V. out This indicates the output voltage value of the rectifier 24, V bat This refers to the voltage value of the energy storage device 40. As described later, the VCR 30 performs MCPT control and can therefore be referred to as the MCPT controller 30 or simply the controller 30.

[0026] The energy storage device 40 is any device that stores electricity internally, 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 repeatedly multiple times (not just once) by being recharged. The battery 40 may be, for example, a linium-ion battery, a nickel-metal hydride battery, or an all-solid-state battery. However, the specific example of the energy storage device 40 is not limited to a battery. In addition, the energy storage device 40 may be a capacitor. Alternatively, the energy storage device 40 may be a combination of a battery and a capacitor. Hereinafter, the energy storage device 40 will preferably be a secondary battery.

[0027] "Overview of Maximum Current Point Tracking Control (MCPT)" Referring to Figures 2(A) to (C), the output of the rectifier 24 side of the rectenna 20, which receives energy transmitted from the power transmission antenna section 12 of the power transmission device 10 in the system shown in Figure 1, is illustrated using three graphs. Note that the power transmission antenna section 12 and the power receiving antenna section 22 are separated by a distance d of 500 mm from each other. Referring to Figure 2(A), the horizontal axis shows the resistance value connected from the output terminal of the rectifier to ground, and the vertical axis shows the correspondence between voltage (solid line) and current (dashed line). Referring to Figure 2(B), the horizontal axis shows the resistance value connected from the output terminal of the rectifier to ground, and the vertical axis shows the correspondence between voltage (solid line) and power (dashed line). Referring to Figure 2(C), the horizontal axis shows the resistance value connected from the output terminal of the rectifier to ground, and the vertical axis shows the correspondence between power (solid line) and current (dashed line).

[0028] Referring to Figure 2(A), it can be seen that the output voltage increases as the resistance value increases, while the output current increases as the resistance value decreases. On the other hand, since power is calculated as the product of current and voltage, as shown in Figures 2(B) and (C), it can be seen that the power is maximized when the resistance value is an intermediate value (for example, 20kΩ).

[0029] When wireless power transfer is performed using a microwave method, there are unique challenges, such as the limited amount of energy that can be transmitted. Furthermore, the input impedance of the energy storage device 40 may be relatively low compared to the output impedance of the rectifier 24 on the receiving side. In this case, it is necessary to adjust (increase) the apparent input impedance of the energy storage device 40. When the input impedance of the energy storage device 40 is appropriately adjusted, the voltage control resistor 30 generally performs MPPT control to adjust it to the operating point where the output power of the rectifier 24 is maximized (see Figure 22).

[0030] As shown in Figures 2(B) and (C), power exhibits a bell-shaped or convex graph. Therefore, determining 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 Figures 2(B) and (C), the point of maximum power and the point of maximum current do not coincide. In order to charge the energy storage device 40 as in this embodiment, it is desirable to maximize the current, so applying MPPT presents problems.

[0031] In this embodiment, as described above, it is assumed that there is a problem if the output of the rectifier 24 is transmitted directly to the energy storage device 40. However, simply applying MPPT as a control method is undesirable because it causes a decrease in current. This is because MPPT cannot adjust the rectifier 24 to the operating point where the output current is maximum. Therefore, in this embodiment, the 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 Figures 2(A) and (C), the voltage and current are at their minimums at the theoretical maximum current value, which is undesirable. MCPT is intended to maximize the current value within the range where the required voltage or power value can be secured.

[0033] As illustrated in (A) of FIG. 1, for example, when power is supplied to the multi-joint robot 100, the operable region changes 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). Therefore, the distance d between the power transmission side and the power reception side changes, and the operating point at which the output current on the power reception side becomes maximum does not become constant. To address this problem, it is conceivable to prepare a dedicated algorithm that can handle various environments.

[0034] However, when preparing a dedicated algorithm, power will be consumed by the control itself. In particular, the more complex the algorithm becomes, or the more complex the components used in response become, the more likely it is to consume a larger amount of power. When performing wireless power supply based on the microwave method, since the power supply capacity is limited, 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 by using a CPU and memory. For example, in the technology disclosed in Patent Document 1 above, control is performed using an MCU (microcontroller unit) 51. Usually, an MCU is a microprocessor that incorporates many peripheral functions such as memory such as ROM and RAM, and I / O related functions. Also, the control unit 170 includes a memory 173 in which a plurality of table data is stored.

[0036] In the first embodiment, the purpose is to enable MCPT control with low power consumption. Referring to FIG. 3, in the figure shown in FIG. 1(A) where the horizontal axis represents the resistance value and the vertical axis simultaneously represents the voltage value and the current value, an application example of MCPT control is shown. In this figure, as shown by the two thick horizontal lines, the battery voltage (voltage value of the power storage device 40) V bat has a margin ΔV upward with respect to a predetermined lower value. The voltage value V out is within this range (V bat and V batIt is preferable that the voltage value falls within the range of +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 Figure 3).

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

[0038] In Figure 4, the dashed curve shows the output current on the rectifier 24 side, the solid curve shows the output voltage on the rectifier 24 side, and the thick straight line shows the battery voltage V of the energy storage device 40. bat And a voltage "V" above a predetermined value ΔV from this point. bat This indicates "+ΔV". In MCPT control, the battery voltage V bat The predetermined upper limit "V bat The current value I is maximized so that it stays within the range of +ΔV. For example, in the values ​​of V4, V3, and V2 in Figure 3, the output voltage value V OUT The above value "V bat This is undesirable because it exceeds +ΔV. On the other hand, in V1 of Figure 4, the output voltage value V OUT The above value "V bat This is preferable because it is below +ΔV. Note that in this state, the output voltage value V OUT is the battery voltage V bat It surpasses that.

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

[0040] Battery voltage V batIn contrast, a margin shown in ΔV can be arbitrarily set depending on the embodiment. For example, ΔV is about 100mV. The finer ΔV is, the higher the control accuracy, but the power consumption tends to increase. In reality, the minimum value of ΔV is about 10mV. The maximum value can be increased by increasing ΔR, so theoretically it can be increased indefinitely, but it is, for example, about 10V.

[0041] The resistance R is preferably adjustable in steps of equal magnitude ΔR. ΔR can be set arbitrarily depending on the embodiment. For example, ΔR is about 100Ω. Similar to ΔV, finer ΔR values ​​increase control accuracy, but tend to increase power consumption. In practice, the minimum value of ΔR is about 1Ω. The maximum value can theoretically be arbitrarily large, but is typically around 1MΩ.

[0042] By applying MCPT control, the apparent input impedance of the energy storage device 40 can be adjusted. In particular, using MCPT allows the operating point of the rectifier 24 to be adjusted to be close to the operating point where the output current is maximized. This system can adapt to any environment; specifically, the rectifier 24, whose voltage-current characteristics change according to distance d, can efficiently charge the energy storage device 40 under any circumstances. As will be described later, this control can be implemented with basic electronic circuits and can be configured without requiring high-power devices such as memory or a CPU. Therefore, it has the excellent effect of achieving low power consumption as a whole system.

[0043] "MCPT Flow" Referring to Figure 5, an example of the MCPT control process flow performed in VCR30 is shown. In the flow in Figure 5, MCPT control is started in step S201. This start can be performed at any time; for example, it may be started when supplying power to any device (e.g., a sensor) within the industrial robot 100, or at the same time as starting to use the industrial robot 100 (e.g., powering it on).

[0044] When control is initiated, VCR30 sets the resistance value to its initial value in step S202. For example, the resistance value may be set to its maximum value. out =R max This means that, in the graphs illustrated in Figure 3 or Figure 4, control begins from the far right.

[0045] Note that 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 midpoint of the graph shown in Figure 3 or Figure 4 / the value between the rightmost and midpoint of the graph shown in Figure 3 or Figure 4). If an intermediate value is selected as the initial value, that value may be a value empirically derived by repeating the control multiple times, depending on the embodiment. On the other hand, if the maximum value is selected as the initial value, the empirically derived work described above can be eliminated.

[0046] Note that the minimum value (for example, the leftmost value in the graph shown in Figure 4) is not selected as the initial value. The minimum resistance value is undefined, and the battery voltage (V bat This is because it fluctuates greatly depending on the factors. The following assumes that in step S202, the resistance value is set to the maximum value as the initial value. out =R max ".

[0047] Next, in step S203, the VCR30 outputs current I out is a predetermined maximum value I bat_max "I" determines whether it is below or below out bat_max " For example, in Figure 4, the reference numeral I4 indicates the output current value I out is a predetermined maximum value I bat_max It is determined that the value is below a certain level. In other words, in this situation, it is determined that the desired maximum current value has not been obtained.

[0048] Next, if VCR30 is yes in step S203, proceed to step S204 and output voltage V out The predetermined maximum value "V​bat Determine whether it exceeds "+ΔV". For example, in Figure 4, at symbol V4, the output voltage value V out The above value "V bat It is determined to be greater than "+ΔV".

[0049] Next, if VCR30 is yes in step S204, then in step S205 the resistance value is reduced by a predetermined magnitude ΔR. out =R out -ΔR」. For example, in the graph shown in Figure 4, the resistance is reduced by the magnitude of R3. As a result, the voltage decreases from V4 to V3, and correspondingly, the current increases from I4 to I3.

[0050] As steps S203, S204, and S205 are repeated by VCR30, the resistance decreases stepwise (R3, R2, R1), and accordingly the voltage decreases stepwise (V4, V3, V2, V1), while 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, it is possible to change the magnitude of the resistance. For example, a relatively large resistance may be selected at the far right of Figure 3 or Figure 4. Also, a relatively small resistance may be selected in the middle of Figure 3 or Figure 4. As a result of repeating steps S203, S204 and S205 above, in the determination in step S204 above, for the pair (V1, I1), the output voltage V out The predetermined maximum value "V bat A state occurs where it is determined that the output voltage does not exceed "+ΔV". For example, in the graph shown in Figure 3, the output voltage V out The value V1 is, "V bat This indicates a state where the value does not exceed "+ΔV". As a result, I4, which corresponds to this V4, can be selected as a suitable current.

[0051] Meanwhile, the output current I is generated by VCR30 in step S203. out is a predetermined maximum value I bat_maxWhen it is determined to be above the threshold, in step S203 the result is no, and in step S206 the resistance value is increased by a predetermined amount ΔR. out =R out +ΔR」. Similarly, the output voltage VCR30 is output in step S204. out The predetermined maximum value "V bat When it is determined that the value is below +ΔV, the result in step S204 is no, and therefore in step S206 the resistance value is increased by a predetermined amount ΔR. out =R out +ΔR」. For example, in the graph shown in Figure 3, the output voltage V out The value V0 is "V bat The value is below +ΔV. In this case, as shown in the graph in Figure 3, the resistance is increased by the magnitude of R0. As a result, the voltage value V0 increases to V1, securing the desired voltage value, and the current value is suppressed accordingly.

[0052] Therefore, in the flowchart of Figure 5, the target voltage value V out However, there are two thresholds "V bat +ΔV" and "V bat It determines whether or not it falls within the region between " and ". That is, V out ga V bat If the value is less than +ΔV, it means the voltage value is within the appropriate range; conversely, if it is greater than +ΔV, it means the voltage value is not within the appropriate range.

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

[0054] Thus, in the flowchart of Figure 5, because continuous control is performed, the voltage value cannot remain permanently at V1, but mainly fluctuates between V1 and V2. In other words, as a result of applying MCPT control, the voltage eventually reaches a state of "oscillating near the optimal value," achieving the ideal state for this control.

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

[0056] "Components of MCPT" The means of performing each flow in Figure 5 will be explained in detail below with reference to Figures 6 to 10. Note that the configurations shown in Figures 6 to 10 are merely examples, and this embodiment is not limited to the forms shown in these figures.

[0057] Figure 6 is an example of a circuit 300 that implements step S203 of Figure 5. In other words, the figure shows that in step S203, the output current I out is a predetermined maximum value I bat_max "I" determines whether it is below or below out bat_max Circuit 300 is shown as an example. As shown in the figure, this circuit 300 is composed of linear current-dependent voltage sources 310 and 320 and a comparator 330, and "I out " and "I bat_max Step S203 may be constructed by comparing it with the following.

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

[0059] A comparator 330 is a device that compares two voltages or currents and switches its output depending on which is larger. In the illustrated example, the above voltage V(I out ) and voltage V(I out_max The two values ​​are input to comparator 330, and the output is switched depending on which value is larger. Voltage V(I out The value of the voltage V(I out_max If the input value is higher than the specified value, the output of comparator 330 may reach the maximum positive voltage, and conversely, it may reach the maximum negative voltage. Note that the input values ​​may be exactly the same, but in that case, it is generally considered that there are no technical problems. If the logic is "yes," it outputs 1; if "no," it outputs 0. The same applies to the following explanation.

[0060] Figure 7 is an example of a circuit 400 that implements step S204 in Figure 5. In other words, the figure shows that in step S204, the output voltage V out The predetermined maximum value "V bat "V" determines whether it exceeds "+ΔV". out >V bat A circuit 400 with +ΔV is shown as an example. As shown in the figure, this circuit 400 is constructed using a voltage source 410 and a comparator 420, and V out and "V bat Step S204 may be constructed by comparing it with "+ΔV".

[0061] For example, the value V of a voltage source operating as a constant voltage electrical circuit. bat The output of the connected voltage source 410 is input to the comparator 420 so that a predetermined voltage value ΔV is added to it. out The value is directly input to comparator 420. These two values ​​are compared, and if the logic is yes, 1 is output; otherwise, 0 is output. The same applies to the following explanation.

[0062] Figure 8 illustrates an example of implementing the output logic of circuit 300 in Figure 6 and the output logic of circuit 400 in Figure 7 using a NAND500. Specifically, the figure illustrates a circuit that realizes the flow using the output logic of Figure 6 and the output logic of Figure 7, and in particular, the NAND500's NAND500 is used. The NAND500 can be constructed as the negation (NOT) of the result of a logical AND. Generally, the output is 0 only when all inputs are High, and the output is 1 if there is at least one Low input.

[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 negated logical AND of the NAND500 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 negated logical AND of the NAND500 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 negated logical AND of the NAND500 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 negated logical AND of the NAND500 outputs 1 (yes).

[0064] Using the above characteristics, the truth table for NAND500 can be defined 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 500 outputs a negative logical product of 0 (no). Also, when the output of the first comparator 330 is 1 (yes) and the output of the second comparator 420 is 0 (no), the NAND 500 outputs a negative logical product of 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), in this embodiment, the negative logical product of the NAND 500 can be ignored (see "don't care"). Also, when the output of the first comparator 330 is 0 (no) and the output of the second comparator 420 is 0 (no), the NAND 500 outputs a negative logical product of 1 (yes).

[0065] In the above truth table, when 1 is output, the resistance value R out may be increased to a predetermined magnitude as "R out +ΔR". Also, in the above truth table, when 0 is output, the resistance value R out may be decreased to a predetermined magnitude as "R out -ΔR". The value of ΔR can be determined in advance. Note that it is possible to modify the above truth table.

[0066] FIG. 9 and FIG. 10 are diagrams illustrating a circuit 600 that implements steps S205 and S206 of FIG. 5. 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 according to the output logic of FIGS. 6 and 7. That 1 is input means that R out becomes smaller. Also, that 0 is input means that R outThis means that the value will increase. The output of counter 610 is configured to be sent to D / R converter (Digital to Resistance converter) 620. Note that it is possible to use a D / A converter (Digital to Analog Converter) instead of a D / R converter.

[0067] Referring to Figure 10, the configuration schematically shown in Figure 9 is illustrated in more detail, and the D / R converter 620 has voltage control resistors (see 641, 642, and 643). In the counter 610, the counter increments each time a 1 is input, and in the D / R converter 620, the resistance value (see 641, 642, and 643) is increased by turning off one switch each time the counter increments. Preferably, the resistance value (see 641, 642, and 643) is increased in steps and equally by a predetermined magnitude.

[0068] Referring to Figure 10, the D / R converter 620 has multiple resistors 641, 642, and 643 connected in series, and switches 631, 632, and 643 are provided to select each of the resistors 641, 642, and 643. The magnitudes of each resistor 641, 642, and 643 are equal. The digital counter 610 in Figure 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 a 1 is input, the more times switches 631, 632, and 633 are closed. Corresponding to this, V out and V bat The resistance values ​​641, 642, and 643 between these points are configured to decrease. For example, referring to the graph in Figure 4, this results in a shift from the right side of the graph to the left side.

[0069] Thus, in circuit 600, switches 631, 632, and 643 are turned off one by one each time the count increases, so the values ​​of resistors 641, 642, and 643 are configured to change in steps. In Figure 10, resistors 641, 642, and 643 are connected in series, but the number, size, and arrangement of these resistors 641, 642, and 643 can be changed in various ways depending on the embodiment. Also, the values ​​of resistors 641, 642, and 643 do not necessarily have to be the same. For example, when control is started from the rightmost position in Figures 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 simple components illustrated in Figures 6 to 10 and the relatively simple flow illustrated in Figure 5. By adopting this configuration, the use of complex components and flows can be avoided. In particular, MCPT control can be realized without using high-power, expensive devices such as memory (storage device) and CPU (microcontroller). As a result, MCPT control can be performed to take an 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 a suitable operating point with low power consumption.

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

[0072] Referring to FIG. 11, in the modified example of MCPT control, the voltage value is compared with two predetermined threshold values (refer to the two horizontal thick lines in FIGS. 3 and 4), and the voltage value V OUT is determined whether it is within the range of a predetermined upper limit (V bat +ΔV) and a lower limit (V bat ), respectively. That is, although the current value is maximized, it is not preferable to deviate from the reference of the lower limit of the voltage required for the power storage device. For this reason, VCR30 may determine that the output voltage V out is below a predetermined maximum value "V bat +ΔV" and above a predetermined threshold value V bat through steps S303 and S304.

[0073] In FIG. 11, VCR30 makes the following determination. V bat <V out <V bat +ΔV For example, assume that a state indicated by the symbol V0 occurs under some conditions. That is, in the determination of step 304, the output voltage V out is below a predetermined maximum value "V bat +ΔV", and in the determination of step 306, it is determined that the output voltage V out is below a predetermined threshold value V bat . In this case, VCR30 then performs control to increase the resistance value by a predetermined amount ΔR in step S307, "R out =R out +ΔR". As a result, referring to FIG. 4 for example, in the state of V0, when the resistance increases by R0, V0 increases to V1. As a result, VCR30 may determine that the output voltage V out is below a predetermined maximum value "V bat +ΔV" and above a predetermined threshold value V bat .

[0074] In the flowchart illustrated in FIG. 11, like S304 and S306, the value of V out is compared with V bat and Vbat It compares each threshold with +ΔV. However, the flowchart illustrated in Figure 5 also encompasses this technical concept. This is because V out > V bat Even if +ΔV is No, V is always out > V bat This is because ΔV is set to satisfy the condition. Therefore, when comparing Figure 5 and Figure 11, the flow shown in Figure 5 is preferable from the viewpoint of configuring a more compact flow and minimizing the required components. However, in the case of Figure 11, there is a possibility of further reducing unnecessary operations. Depending on the embodiment, modifications can be made to the flow shown in Figure 5. For example, the start and end conditions may be set in more detail (e.g., by referencing the time). [Examples]

[0075] "Example of modification to power receiving device 1" The power receiving device 1 has been described above with reference to Figures 1 to 11, but the configuration of the power receiving device 1 is not limited to that shown in Figure 1. Examples of modifications to the power receiving device 1 shown in Figure 1 will be described below with reference to Figures 12 to 16. Figure 12(A) shows a simplified representation of the power receiving device 1 in Figure 1(B), indicating that the output of the rectenna 20 is transmitted to the MCPT controller 30, and then this output is supplied to the battery 40. Referring to Figure 12(B), an example of a modification of the power receiving device 1 illustrated in Figure 12(A) is shown. As shown in the same figure, the output of the rectenna 20 may be connected to a buck converter or a step-down converter 50 before the MCPT controller 30. The buck converter 50 may also be a DC-DC converter that obtains an output voltage lower than the input voltage. The step-down output from the buck converter 50 may be supplied to the MCPT controller 30.

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

[0077] Instead of the example in Figure 12(B) or (C), the output of the rectenna 20 may be connected to a buck-boost converter that has both boost and buck converter functions before the MCPT controller 30. In this case, the buck converter and boost converter may be configured in parallel. Alternatively, the buck-boost converter may be a single component. For example, the circuit configuration illustrated in Figure 13 or Figure 14 can be used.

[0078] Referring to Figure 13, an example is shown in which the output of the rectenna 20 is connected in parallel to the buck converter 50 and the boost converter 60 in front of the MCPT controller 30. This circuit can function as a buck-boost converter, where either the function of the buck converter 50 or the boost converter 60 can be selected by a switch, and its boosted or bucked output can be supplied to the MCPT controller 30. For example, when only switch SW2 is turned on, only the function of the buck converter 50 may be selectively applied, and when only 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 the buck converter 50 and the boost converter 60 may be disabled. That is, since the efficiency of the converters is generally 90% or less, it may be possible to switch between using the converters and not using them, taking this efficiency into consideration. Therefore, in the circuit shown in Figure 13, the MCPT controller 30 monitors the output voltage of the rectenna 20 and the desired voltage V out By comparing the states, if they are equivalent, only switch SW1 may be turned on; if the difference is greater, only switch SW2 may be turned on; and if the difference is less, only switch SW3 may be turned on. This control is performed by feedforward.

[0080] Figure 14 shows an example of a modification to the power receiving device, in which a buck-boost converter has been added. Referring to Figure 14, the buck boost converter 65 is configured as part of the same circuit (configured as a single device), and switches SW4 and SW5 allow switching between using the buck boost converter 65 and not using the buck boost converter 65.

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

[0082] Thus, the buck converter (step-down DC-DC converter) does not need to be functioning at all times. As described above, the output of the rectenna 20 may be selectively connected to the buck converter (DC-DC) 50 using a switch relative to the MCPT controller 30. In particular, since impedance mismatch can occur when using a DC-DC converter, reducing efficiency, the DC-DC converter may be selectively used by operating a switch only when it is necessary to increase the voltage.

[0083] Furthermore, the MCPT controller 30 monitors the output voltage of the rectenna 20 (output of the rectifier 24) and sets its value to the desired voltage V out This is compared. If, as a result, it is determined that the output voltage of the rectenna 20 is low, the switch may be turned on and only the boost converter 60 may be used selectively. Also, if it is determined that the output voltage of the rectenna 20 is high, the switch may be turned on and only the buck converter 50 may be used selectively. Furthermore, if the output voltage of the rectenna is V out If it is determined to be equivalent, you may turn on the switch and select a situation where neither the boost converter 60 nor the buck converter 50 is selected.

[0084] Referring to Figure 15, the effects of adding the buck converter 50 and / or boost converter 60 will be explained. As can be seen from the output diagram when using the buck converter (step-down DC-DC converter) 50 exemplified in Figure 15, the maximum output power does not increase by using the buck converter 50. However, by using the buck converter 50, the voltage can be lowered while the power, which is the product of voltage and current, remains constant. In other words, a change in the relationship can be obtained where the voltage value is decreased from large to small, the current is increased from small to large, and the power is kept constant. That is, even with the same resistance value (horizontal axis) in the graph of Figure 15, the current value can be increased by adding the buck converter 50 and / or boost converter 60. In this case, referring to Figure 15, it can be seen that the current value is shifted horizontally. Therefore, by adding the buck converter 50 and / or boost converter 60 to the power receiving device 1, the effect of increasing the current value with the same resistance value can be obtained compared to the case without it. By applying the flow in Figure 5 to this configuration of power receiving device 1, the effect of maximizing the current can be obtained.

[0085] Figure 16 shows an example of a modification to the power receiving device in which an LDO (Low Drop-Out regulator) 70 has been added. Referring to Figure 16, in another embodiment, the output of the rectenna 20 may be connected to the LDO 70 before the MCPT controller. The LDO 70 is also called a low-loss regulator. It is a series regulator that can operate with an extremely 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. By using the LDO 70, voltage adjustment (and corresponding current adjustment) can be performed more effectively compared to not using it.

[0086] The above describes examples of modifications to the power receiving device 1 illustrated in Figure 1 with reference to Figures 12 to 16, but the examples of modifications to the power receiving device 1 are not limited to these. For example, in another embodiment, the output of the rectenna 20 may be connected to a buck converter 50, a boost converter 60, or a buck-boost converter 65 downstream of the MCPT controller 30 (not shown). Furthermore, in other embodiments, the output of the rectenna 20 may be connected to the LDO 70 downstream of the MCPT controller 30 (not shown).

[0087] "Feedback in MCPT control" Furthermore, it is possible to add various components to the power receiving device 1 illustrated in Figures 1, 12 to 16. For example, as illustrated in Figure 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) of the energy storage device 40 for its control. bat The value is observed. This value may be transmitted to the data receiver 8 on the power transmission device 10 side via the data transmitter 80 on the power receiving device 1 side. In this case, the frequency of data transmission can be adjusted according to the power reception status of the power receiving device 1. For example, V batIf the value of is large, there is sufficient power on the 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 improves the reliability of data communication between the transmitting device 10 and the receiving device 1. On the other hand, V bat If the value is small, there is insufficient power on the 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 makes it possible to reduce the overall power consumption of the receiving device 1.

[0089] In particular, in fields such as factory automation, when the power receiving device 1 is installed in a location where its position is constantly changing, such as the robot hand unit 120 or the robot arm unit 110 (see Figure 1), it is necessary to obtain data correctly. As described above, in this embodiment, the MCPT controller 30 is always V bat Because it is being observed, it is constantly monitoring whether or not there is a power margin on the power receiving device 1 side. 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 transmission device 10 and the power receiving device 1 changes, changes in the power transmission status can be tracked at a high frequency.

[0090] As described above, the transmission frequency of the transmitter 80 can be changed depending on the power reception status of the power receiving device 1. For example, if the power reception status is good, the transmitter 80 may transmit at a frequency of 1 Msec. If the power reception status is not good, the transmitter 80 may transmit at a frequency of 5 Msec. Since the power receiving device 1 consumes power for the data transmission by the transmitter 80 itself, if the power reception status deteriorates, the overall power consumption of the system can be reduced by transmitting data at a lower frequency. Conversely, if there is sufficient power in the power reception status, the system can transmit at a higher frequency to improve traceability.

[0091] Furthermore, as illustrated in Figure 18, the power receiving device 1 may perform other control functions by transmitting a feedback signal to the power transmitting device 10. As described above, in this embodiment, the MCPT controller 30 is V bat Observe V. bat If the value is too large, the energy storage device 40 of the power receiving device 1 may become overcharged. In that case, the MCPT controller 30 may send a feedback signal to the power transmitting device 10 to stop the transmission (or reduce the amount of transmitted energy) and reduce the power consumption of the entire system. On the other hand, V bat If the value is too small, the energy storage device 40 of the power receiving device 1 may over-discharge. In that case, the MCPT controller 30 may send a feedback signal to the power transmitting device 10 to control the power transmitting device 10 to increase its transmission (or increase the magnitude of the transmitted energy).

[0092] The power transmission device 10 transmits energy E to the power receiving device 1 via the power transmission antenna 12 (see Figure 1), but multiple power transmission antennas 12 can be used. In that case, the power transmission device 10 may, for example, control the transmission of energy E from multiple power transmission antennas 12 simultaneously if one power transmission antenna 12 cannot transmit sufficient energy E. The number of power transmission antennas 12 can be any number of two or more.

[0093] The energy storage device 40 may have its lifespan reduced by over-discharge / over-charge. Therefore, by transmitting a feedback signal to the power transmission device 10 according to the power receiving status of the power receiving device 1 and controlling the power transmission antenna 12, it is possible to avoid undesirable damage to the energy storage device 40 and extend the lifespan of the energy storage device 40. Furthermore, the lifespan of the power transmission device 10 may be reduced by heat (i.e., operating time). Therefore, by sending a feedback signal to the power transmission device 10 according to the power receiving status of the power receiving device 1, and performing control to adjust the transmission state of the power transmission antenna 12 so that it does not always remain at high output, the lifespan of the power transmission device 10 can be extended. Therefore, by performing the above control, this embodiment can extend the lifespan of both the power transmission device 10 and the power receiving device 1. For this reason, this embodiment can contribute to solving the challenges of extending the lifespan that are unique to factory automation (FA), especially when applied in the field of FA. [Examples]

[0094] In Examples 1 and 2, the MCPT controller 30 of the power receiving device 1 is configured to perform low-power control. In particular, the MCPT controller 30 is configured to perform MCPT control without using memory or a CPU. This contributes to a significant reduction in the overall power consumption of the power receiving device 1. This effect is particularly suitable when wireless power transfer is performed using a microwave system, where there is an upper limit to the energy capacity that can be transmitted. In contrast, in Embodiment 3 illustrated in Figures 19 to 21, the MCPT controller 200 of the power receiving device 1A is configured to perform control using memory 240 and CPU 260. In this case, the overall power consumption of the power receiving device 1A is increased, but it enables more advanced control. Embodiment 3 can be applied when the conditions for transmittable energy capacity are met.

[0095] Referring to Figure 19, the components of the MCPT controller 200 of the power receiving device 1A are schematically illustrated. As shown in the figure, the MCPT controller 200 comprises a CPU (processing unit or 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 unit that controls the whole system, an arithmetic unit, registers for temporary data storage, an interface to memory 240, and interfaces to input / output devices for peripherals. Memory 240 is defined as a device capable of storing data. For example, memory 240 is a primary storage device that can be directly accessed by the CPU 260, or a secondary storage device accessed using an input / output channel, etc. For example, memory 240 can be any media, a fixed disk, volatile or non-volatile random access memory, a CD, a DVD, a flash drive, removable media (e.g., a thumb-sized miniature memory) that can be attached to a corresponding interface (e.g., a USB port), or similar.

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

[0097] Memory 240 stores the above-mentioned programs as well as various databases (DBs), such as Table 270 (see Figures 20 and 21). A "database" is a functional element (storage unit) that stores a data set so that it can handle arbitrary data operations (e.g., extraction, addition, deletion, overwriting, etc.) from the processor or an external computer. The implementation method of a database is not limited; for example, it may be a database management system, spreadsheet software, or text files such as XML or JSON. Hereafter, the data set stored on memory 240 will simply be referred to as a table.

[0098] As described above, the CPU 260 can store any calculated value in memory 240. Furthermore, the CPU 260 can retrieve the value stored in memory 240 at any time. For example, as shown in the label 250 "Comparator", the CPU 260 can retrieve the calculated current value I from the immediately preceding value (the value from one step prior, I) that has already been calculated and stored in memory 240. out_tmp ) and the currently calculated value (value for the current step, I out ) may be compared with the result. Based on the result, the CPU 260 can perform control for the next step (the value after one step).

[0099] For example, the CPU 260 may, based on the above comparison operation and the output of the comparator 250, control ΔR (change in resistance) as shown in reference numeral 220. This allows the current I to change based on the change in resistance ΔR, as illustrated in Figures 3 and 4. bat The value of is appropriately changed to send the voltage value V to the energy storage device 40. bat You may adjust it.

[0100] CPU260 uses the value I from the previous step for the current value I. out_tmp and the value of the current step I out The control of ΔR (resistance change) may be changed based on the difference. For example, if the above difference is large, the CPU 260 may control ΔR (resistance change) at a relatively large rate. Also, if the above difference is small, the CPU 260 may control ΔR (resistance change) at a relatively small rate.

[0101] The comparison operations performed by the CPU 260 are not limited to the above example. For example, as shown in the label 250 "Comparator", the CPU 260 may compare the calculated current value I with past values ​​stored in memory 240 (value from one step ago, two steps ago, or three or more steps ago) and the current value (value from the current step). Based on the result, the CPU 260 may adjust the value of ΔR (resistance change) to control the next step (value from one step later, two steps later, or three or more steps later).

[0102] In fields such as factory automation, for example, 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 status 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 distance d that depends on the change in this range, the change in the suitable resistance value ΔR can also be known in advance.

[0103] In particular, the CPU 260 controls the resistance value ΔR based on distance d. In this process, the values ​​of ΔR and other parameters corresponding to various changes in conditions can be pre-created in Table 270 (see Figures 20 and 21) and stored in memory 240. The CPU 260 may then refer to Table 270 stored in memory 240 when performing the control to change ΔR. Figures 20 and 21 illustrate a power receiving device that performs MCPT control using Table 270 stored in memory 240. As illustrated in these figures, the change in distance d and the voltage value V of the energy storage device are shown. bat The changes in [the variable] and the corresponding changes in the resistance value ΔR can be compiled into a table and stored in memory 240 beforehand.

[0104] For example, referring to Table 270, the voltage value V of the energy storage device 40 is... batIt has been determined that a 1kΩ resistor is preferable when the voltage is 3V and the distance d is 1m. Furthermore, when the distance d changes from this state to 2m, the voltage remains 3V. bat In relation to this, a resistance of 1.5kΩ is deemed preferable. Also, the voltage value V of the energy storage device 40 bat It has been determined that a 2kΩ resistor is preferable when the voltage is 3.2V and the distance d is 1m. Furthermore, when the distance d changes from this state to 2m, the voltage remains 3.2V. bat In response to this, a 2.5kΩ resistor is deemed preferable.

[0105] Thus, the change in distance d and the voltage value V of the energy storage device 40 are related. bat In response to the changes, suitable resistance values ​​can be compiled in Table 270 and stored in memory 240. These values ​​can be determined by actual measurement (hardware) according to each 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 ​​that make up the table are the distance d and the voltage value V of the energy storage device 40. bat The resistance value is not limited to one. Furthermore, there may be multiple tables depending on the embodiment, and the CPU 260 can select the 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 resistance value currently being used is far from the optimal value corresponding to that distance d, the CPU 260 can change the resistance value to the optimal value. Therefore, even if the distance d between the power transmission device 10 and the power receiving device 1 changes, the CPU can always perform optimization control to bring the resistance value closer to the optimal value.

[0107] This control is not limited to the currently required resistance value, but may also be applied to values ​​that are predicted to be required one step or more steps in the future. For example, if a power receiving device 1A (see power receiving device 1 in Figure 1) is installed in a moving part such as the robot hand 120 or the robot arm 110, the future movement of the machine 100 can be predicted, and therefore, according to that prediction, the change in resistance may be predicted in advance not only for the current state but also for the state one step or more steps in the future.

[0108] CPU260 may calculate values ​​that cannot be directly obtained from Table 270 based on the above Table 270. For example, CPU260 may obtain the necessary values ​​by interpolation or extrapolation based on the values ​​in Table 270. For example, if information between two consecutive points M1 and M2 is needed, the information between the two points can be determined based on the information of these two points (interpolation). For example, if CPU260 needs the resistance value for 3V at a distance d of 1.5m, it can determine the value of 1.25kΩ by interpolating between two values: the resistance value of 1kΩ at a distance d of 1m and the resistance value of 1.5kΩ at a distance d of 2m. Furthermore, if information outside of two consecutive points M1 and M2 is needed, information on the extension of these two points can be obtained based on the information of these two points (extrapolation). For example, if CPU260 needs the resistance value for 3V at a distance d of 2.5m, it may obtain the value of 1.75kΩ by extrapolating the resistance value of 1kΩ at a distance d of 1m and the resistance value of 1.5kΩ at a distance d of 2m.

[0109] Thus, CPU260 may calculate the necessary information based on Table 270 above. Note that when CPU260 performs interpolation or extrapolation, it is not limited to calculating the mean. For example, if a value suddenly increases or decreases under certain circumstances, CPU260 may calculate a value corresponding to that change rather than calculating the mean from the values ​​in Table 270. For example, statistical data (variance, standard deviation, function, etc.) may be associated with Table 270 to represent that change.

[0110] Preferably, the MCPT controller 200 controls the voltage value V in the power receiving circuit. OUT The following can be constantly monitored. Furthermore, the distance d between the power transmission device 10 and the power receiving device 1A can be determined by several methods. Therefore, the CPU 260 can select the optimal resistance value based on these values. Figure 20 shows the power received on the power receiving device 1A side, V out This figure illustrates a case where distance d is calculated based on the received power V. out It is possible to measure the received power V, but generally, the distance d is equal to the received power V. out This can be correlated with the measured power received V. out If the value is relatively large, CPU260 can infer that the distance d is relatively small. Also, the measured received power V out If the value is relatively small, CPU260 can infer that the distance d is relatively large. Power received V out The correspondence between and distance d can be precisely measured or calculated in advance depending on the embodiment. Therefore, the CPU 260 determines the voltage value V on the output side of the rectifier 24 of the rectenna 20. out Based on this, data regarding the distance d between the power transmission device 10 and the power receiving device 1A can be calculated. The MCPT controller 200 selects the optimal resistance value based on the distance d information calculated by the CPU 260.

[0111] Figure 21 illustrates a case where the power receiving device 1A receives distance d data obtained by the power transmitting device 10. As shown in the figure, 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 status. For example, in the case of the robot hand illustrated in Figure 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 this distance d data via the data receiver 9. On the device side, the power receiving device 1A is equipped with a data receiver 90, and when it transmits the distance d data sent from the data receiver 90, it can transmit that data to the CPU 260. Therefore, the CPU 260 can receive data regarding 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 the optimal resistance value based on the distance d information sent from the data transmitter 9.

[0112] Thus, on the power receiving device 1A side, the CPU 260 receives the power V out The distance d can be determined by measuring (see Figure 20). Alternatively, the CPU 260 can determine the distance d based on the data transmitted from the power transmission device 10 by determining the position of the power receiving device 1A on the power transmission device 10 side (see Figure 21). Note that it is not necessary to provide feedback of the control results from the power receiving device 1A to the power transmission device 10.

[0113] As described above, in the power receiving device 1A of Embodiment 3 illustrated in Figures 19 to 21, it is possible to add various components, as in the power receiving device 1 of Embodiment 2 illustrated in Figures 12 to 18. Furthermore, the present invention can provide a computer program product that enables the MCPT control described above for the MCPT controller 200 of the power receiving device 1A illustrated in Figures 19 to 21.

[0114] A computer program product may be implemented as a program, function, routine, or executable object. Preferably, the computer program product comprises program code that enables the execution of the MCPT control described above. Accordingly, a different aspect of the present invention relates to a computer program product for performing the above-mentioned control when used on an MCPT controller 200 in a power receiving device 1A.

[0115] Computer program products, such as computer program means, can be implemented as files downloadable from memory cards, USB sticks, CD-ROMs, DVDs, or servers on a network. For example, such files may be provided by transferring files containing computer program products over a wireless communication network.

[0116] Those skilled in the art will be able to make various applications and modifications to the above embodiments without departing from the scope of the claims. For example, each part (component) of the power receiving device 1 or 1A may include other components necessary for its operation, and may also include additional components to provide functions other than those described herein. Therefore, it should be understood that the claims of this patent may be implemented in ways other than those specifically described herein. [Explanation of Symbols]

[0117] 1. 1A power receiving device 10 Power transmission equipment 20. Rectenna (receiving antenna) 22 Receiving antenna section 24. Rectifier 30, 200 Controller (Voltage-controlled resistor or MCPT controller) 40. Energy storage devices (batteries or capacitors) 50 Buck Converter 60 Boost Converter 65 Back Boost Converter 70 LDO 80 Data Transmitters 90 Data Receiver

Claims

1. A power receiving device that receives power transmitted from a power transmission device based on a microwave wireless power transfer system, A receiving antenna that receives microwaves, A rectifier functionally connected to the aforementioned receiving antenna, which converts the microwaves into voltage, A power storage device that stores the output from the rectifier, A power receiving device comprising a controller functionally connected to the rectifier and for switching multiple circuits, The voltage-current characteristics of the rectifier change in relation to the power receiving status of the power receiving device. The controller is, A power receiving device that switches between a plurality of circuits having predetermined resistance values ​​such that the output voltage of the rectifier, which indicates the power receiving status of the power receiving device, falls below a predetermined threshold, thereby reducing the difference between the input impedance of the energy storage device and the output impedance of the rectifier.

2. The power receiving device according to claim 1, wherein the power receiving device switches a plurality of circuits having predetermined resistance values ​​so that the voltage value on the output side of the rectifier falls below a predetermined threshold, without using a CPU and memory.

3. The controller is, A means for setting the resistance value to an initial value, A means for determining whether the current value exceeds a threshold, A means for determining whether the voltage value exceeds a threshold, The system includes means for changing the resistance value in steps when the voltage value exceeds a threshold, The power receiving device according to claim 1 or 2, wherein the controller repeatedly determines the current value, determines the voltage value, and makes a stepwise change in the resistance value so as to reduce the difference between the input impedance of the energy storage device and the output impedance of the rectifier.

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

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

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

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

8. A power receiving device that receives power transmitted from a power transmission device based on a microwave wireless power transfer system, A receiving antenna that receives microwaves, A rectifier functionally connected to the aforementioned receiving antenna, which converts the microwaves into voltage, A power storage device that stores the output from the rectifier, A power receiving device comprising a controller functionally connected to the rectifier and for switching multiple circuits, The voltage-current characteristics of the rectifier change in relation to the power receiving status of the power receiving device. The controller includes a CPU and memory, The memory stores information relating the distance between the power transmission device and the power receiving device, the voltage value of the energy storage device, and the resistance value of the output side of the rectifier. The CPU acquires data relating to the distance between the power transmission device and the power receiving device, and the power receiving voltage of the power receiving device, and uses the information stored in the memory to switch between a plurality of circuits having predetermined resistance values ​​so that the output voltage of the rectifier indicating the power receiving status of the power receiving device falls below a predetermined threshold, thereby reducing the difference between the input impedance of the energy storage device and the output impedance of the rectifier.

9. The power receiving device according to claim 8, wherein the controller receives data relating to the 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 the distance between the power transmitting device and the power receiving device based on the 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 and the value of the current step, which are stored in the memory.

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

13. Furthermore, the power receiving device according to any one of claims 1 to 12, 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 energy storage device.

14. Furthermore, the power receiving device according to any one of claims 1 to 12, further comprising a low-loss regulator (LDO) between the rectifier and the controller, or between the controller and the energy storage device.

15. It is equipped with a transmitter that sends a feedback signal to the outside, The power receiving device according to claim 1 or 8, wherein the controller changes the frequency of transmission of a feedback signal from the transmitter to the outside based on the power receiving status of the power receiving device.

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