Power receiving device, power receiving method, and wireless power supply system

Abstract

The present invention provides a power receiving device, a power receiving method, and a wireless power supply system that can efficiently convert received power even when the magnitude of the received power fluctuates according to the radio wave environment. [Solution] The power receiving device of this embodiment includes a power receiving unit that receives wireless power, a switching rectifier unit that rectifies the received wireless power using a target rectifier which is one rectifier selected from among a plurality of rectifiers with different power conversion characteristics, a detection unit that detects the output voltage or output power of the target rectifier, a power conversion unit that controls the output voltage of the target rectifier, a power storage unit that charges and discharges the output power of the power conversion unit, and a control unit that estimates the received power based on one of the output voltage or output power of the target rectifier and information showing the relationship between the input power and output voltage or output power of the target rectifier, and controls the operation of the switching rectifier unit and the power conversion unit based on the estimated received power.

Description

Technical Field

[0001] This embodiment relates to a power receiving device, a power receiving method, and a wireless power feeding system.

Background Art

[0002] A wireless power feeding system that wirelessly transmits and receives feeding power is known. The wireless power feeding system includes a power transmitting device and a power receiving device. The power transmitting device wirelessly transmits the feeding power as a feeding beam (wireless power or RF power). The power receiving device receives the feeding beam as RF (Radio Frequency) power, and converts the received power (hereinafter referred to as received RF power) into DC power and outputs it.

[0003] When the power receiving device converts the received RF power into DC power, a rectifier is used. The power conversion efficiency of the rectifier varies depending on the magnitude of the input power, but the magnitude of the received RF power fluctuates according to the radio wave environment. Therefore, it is difficult to always obtain DC power with high efficiency from the received RF power that varies widely in magnitude using a single rectifier.

[0004] In order to solve such difficulties, it is conceivable to prepare a plurality of rectifiers having different power conversion characteristics, and to select a rectifier that can obtain DC power with high efficiency each time while switching these plurality of rectifiers. However, the operation of periodically switching the rectifier and comparing the output DC power only for the purpose of determining whether it is highly efficient is inefficient because there is a time when a rectifier with low efficiency is used.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The purpose of this embodiment is to provide a power receiving device, a power receiving method, and a wireless power supply system that can efficiently convert received power even when the magnitude of the received power fluctuates according to the radio wave environment. [Means for solving the problem]

[0007] To solve the above problems, the power receiving device according to this embodiment includes a power receiving unit that receives wireless power, a switching rectifier unit that rectifies the received wireless power using a target rectifier which is one rectifier selected from among a plurality of rectifiers with different power conversion characteristics, a detection unit that detects the output voltage or output power of the target rectifier, a power conversion unit that controls the output voltage of the target rectifier, a power storage unit that charges and discharges the output power of the power conversion unit, and a control unit that estimates the received power based on the output voltage of the target rectifier and information showing the relationship between the input power and output voltage of the target rectifier, or based on the output power of the target rectifier and information showing the relationship between the input power and output power of the target rectifier, and controls the operation of the switching rectifier unit and the power conversion unit based on the estimated received power.

[0008] The wireless power receiving method according to this embodiment involves receiving wireless power, rectifying the received wireless power using a target rectifier which is one rectifier selected from among a plurality of rectifiers with different power conversion characteristics, detecting the output voltage or output power of the target rectifier, estimating the received power based on the output voltage of the target rectifier and information showing the relationship between the input power and output voltage of the target rectifier, or based on the output power of the target rectifier and information showing the relationship between the input power and output power of the target rectifier, and selecting a target rectifier based on the estimated received power.

[0009] The wireless power supply system according to this embodiment includes a power transmission device for transmitting wireless power and a power receiving device for receiving wireless power. The power receiving device includes a power receiving unit for receiving wireless power, a switching rectifier unit that rectifies the received wireless power using a target rectifier which is one rectifier selected from a plurality of rectifiers with different power conversion characteristics, a detection unit for detecting the output voltage or output power of the target rectifier, a power conversion unit for controlling the output voltage of the target rectifier, a power storage unit for charging and discharging the output power of the power conversion unit, and a first control unit that estimates the received power based on the output voltage of the target rectifier and information indicating the relationship between the input power and output voltage of the target rectifier, or based on the output power of the target rectifier and information indicating the relationship between the input power and output power of the target rectifier, and controls the operation of the switching rectifier unit and the power conversion unit based on the estimated received power. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram shows the configuration of the power receiving device according to Embodiment 1. [Figure 2] This diagram shows the detailed configuration of the switching rectifier section of Embodiment 1. [Figure 3] This diagram shows an evaluation system for assessing the power conversion characteristics of a rectifier. [Figure 4] This diagram shows the power conversion characteristics of a rectifier. [Figure 5] This diagram shows the power conversion characteristics of a rectifier. [Figure 6] This is a flowchart that explains the details of the operation of the power receiving device. [Figure 7] This is a flowchart illustrating the details of maximum power point control. [Figure 8] This diagram shows the detailed configuration of the switching rectifier section of Embodiment 2. [Figure 9] This diagram shows the detailed configuration of the power conversion unit in Embodiment 3. [Figure 10] This is a diagram showing the configuration of the wireless power supply system according to Embodiment 4. [Modes for carrying out the invention]

[0011] This embodiment will be described below with reference to the drawings. In the drawings, the same or corresponding elements are denoted by the same reference numeral, and detailed descriptions are omitted as appropriate.

[0012] [Embodiment 1] (Configuration of the power receiving device) Figure 1 shows the configuration of the power receiving device 100 according to Embodiment 1. The power receiving device 100 receives a power supply beam (radio power) transmitted from a power transmitting device (not shown) as RF power, converts the received power (hereinafter referred to as received RF power) into DC power, and supplies it to an external load 80. The external load 80 is any electronic device or electronic equipment that operates on DC power.

[0013] The power receiving device 100 includes an RF power receiving unit 10 (power receiving unit), a switching rectifier unit 20, a detection unit 30, a power conversion unit 40, a power storage unit 50, a charge amount calculation unit 51 (calculation unit), and a control unit 60 that controls the operation of the switching rectifier unit 20 and the power conversion unit 40. In this example, the load is provided outside the power receiving device 100 as an external load 80, but the load may also be included inside the power receiving device 100.

[0014] The power receiving unit 10 receives the power supply beam transmitted from the power transmission device and outputs it as the received RF power Prf. The switching rectifier unit 20 includes a plurality of rectifiers with different power conversion characteristics. The switching rectifier unit 20 rectifies the received RF power Prf using one rectifier (target rectifier) ​​selected by the control unit 60 from among these plurality of rectifiers and outputs it as DC power Pdc1.

[0015] Figure 2 shows a detailed configuration of the switching rectifier unit 20. The switching rectifier unit 20 includes an RF switch 21 (first switching unit) that operates according to the command signal Ist1 from the control unit 60, and three rectifiers 22a to 22c with different power conversion characteristics. However, the number of rectifiers is not limited to three; there may be multiple rectifiers.

[0016] The RF switch 21 connects the input of the switching rectifier section 20 and the input of any one of the target rectifiers selected by the control section 60. The outputs of the rectifiers 22a to 22c are connected together at the node 23 (the first combining section) to become the output of the switching rectifier section 20. As a result, the received RF power Prf input to the switching rectifier section 20 is rectified by the target rectifier selected by the control section 60 and output from the switching rectifier section 20 as DC power Pdc1 (= Vrec × Irec). Here, Vrec is the output voltage of the target rectifier, and Irec is the output current of the target rectifier.

[0017] The detection section 30 includes a DC voltage sensor and a DC current sensor. The detection section 30 detects the output voltage Vrec and the output current Irec of the target rectifier, multiplies these values, and calculates the output power Pdc1. The detection section 30 transmits information indicating the output power Pdc1, the output voltage Vrec, and the output current Irec of the target rectifier to the control section 60.

[0018] The power conversion section 40 includes a DC-DC converter circuit that operates according to a command signal Ist2 from the control section 60, and converts the DC power Pdc1 output from the switching rectifier section 20 into DC power Pdc2 and outputs it. Also, a power storage section 50 is connected to the output of the power conversion section 40. As a result, the output voltage of the power conversion section 40 is fixed to the closed-circuit voltage (CCV) of the power storage section 50, which is determined according to the charge amount of the power storage section 50. On the other hand, the input of the power conversion section 40 is the output of the switching rectifier section 20. The maximum value of this output voltage is determined by the received RF power Prf, and the actual output voltage is uniquely determined by also determining the output load state of the switching rectifier section 40. Therefore, the output voltage of the DC-DC converter circuit is fixed, and the input voltage changes. The DC-DC converter circuit performs a boosting or bucking operation, that is, a step-up / down operation, according to the voltage difference between the input and output, and as described above, it is the input voltage that changes in this operating state. Utilizing this property, the control section 60 controls the step-up / down operation of the power conversion section 40 to control the output voltage Vrec of the target rectifier included in the switching rectifier section 20.

[0019] The energy storage unit 50 is composed of a secondary battery or a capacitor, and charges and discharges the DC power Pdc2 output from the power conversion unit 40. Specifically, if the DC power Pdc2 output from the power conversion unit 40 is greater than the power required by the external load 80, the excess power is charged into the energy storage unit 50. On the other hand, if the DC power Pdc2 output from the power conversion unit 40 is less than the power required by the external load 80, the deficit power is discharged from the energy storage unit 50. The charge amount calculation unit 51 measures the power charged and discharged into the energy storage unit 50 and calculates the charge amount of the energy storage unit 50 (the amount of charge stored in the energy storage unit 50) based on this. The control unit 60 may stop the power conversion unit 40 when it approaches full charge and restart it when the charge amount decreases to a predetermined value. Alternatively, the control unit 60 may open the RF switch 21 of the switching rectifier unit 20 when it approaches full charge and close it when the charge amount decreases to a predetermined value. Alternatively, if communication from the power receiving device to the power transmitting device is possible, the control unit 60 may perform control such as sending a power transmission stop request to the power transmitting device when it approaches full charge, and sending a power transmission restart request when the charge level decreases to a predetermined value.

[0020] The control unit 60 is composed of a microcomputer, FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit), etc. The control unit 60 estimates the current received RF power Prf based on information transmitted from the detection unit 30 indicating the output voltage Vrec or output power Pdc1 of the currently selected target rectifier and the power conversion characteristics of the target rectifier. The control unit 60 selects one of the rectifiers 22a to 22c included in the switching rectifier unit 20 as the target rectifier according to the current received RF power Prf. The control unit 60 uses the power conversion unit 40 to control the output voltage Vrec of the target rectifier so that the output power Pdc1 of the target rectifier is maximized.

[0021] (Power conversion characteristics of a rectifier) Here, we will explain the power conversion characteristics of a rectifier. Generally, the power conversion efficiency of a rectifier is determined by the RF power input to the rectifier (input RF power Pin) and the load connected to the output of the rectifier (output load RL).

[0022] Figure 3 shows an evaluation system for evaluating the power conversion characteristics of a rectifier. The evaluation system consists of an RF power supply 101, a rectifier 102, and a variable resistor 103. The RF power supply 101 supplies the input RF power Pin to the rectifier 102. The input RF power Pin corresponds to the received RF power Prf of the power receiving device 100 in Figure 1.

[0023] Rectifier 102 rectifies the input RF power Pin and outputs it as output DC power Pout (=Vrec × Irec). Rectifier 102 corresponds to rectifiers 22a to 22c included in the switching rectifier unit 20 in Figure 2. The output DC power Pout corresponds to the output power Pdc1 of the target rectifier selected from rectifiers 22a to 22c. The variable resistor 103 is the output load RL of the target rectifier 102 and corresponds to the power conversion unit 40, the energy storage unit 50, and the external load 80 of the power receiving device 100 in Figure 1. In the evaluation system in Figure 3, the power conversion efficiency of rectifier 102 is determined by the input RF power Pin and the output load RL.

[0024] First, we focus on the input RF power Pin as the primary parameter for determining the power conversion efficiency of the rectifier. Figure 4 shows the simulation results plotting the relationship between the input RF power Pin and the power conversion efficiency for the three rectifiers 22a to 22c included in the switching rectifier unit 20, using the evaluation system shown in Figure 3. Each plotted point was obtained by adjusting the output load RL so that the output RF power Pout is maximized with respect to the input RF power Pin on the horizontal axis.

[0025] As shown in Figure 4, when each rectifier has different power conversion characteristics, high power conversion efficiency can be obtained for a wide range of input RF power values ​​by selecting an appropriate rectifier as the target rectifier according to the input RF power value Pin. However, the power conversion efficiency of each rectifier initially increases monotonically with increasing input RF power value, but then begins to decrease beyond a certain input RF power value. This region where power conversion efficiency decreases is the region where the output voltage Vrec of the rectifier exceeds the maximum voltage that can be stably output (maximum output voltage), and the rectifier may be damaged in this region. Therefore, in order for the rectifier to operate stably, the output voltage Vrec of the rectifier must be less than or equal to the maximum output voltage, which corresponds to the input RF power Pin input to the rectifier being less than or equal to the maximum power that can be input to the rectifier (maximum input power).

[0026] In this embodiment 1, the control unit 60 estimates the current received RF power Prf (input RF power Pin) by a method described later, and selects from among the rectifiers 22a to 22c included in the switching rectifier unit 20 the rectifier whose maximum input power is equal to or greater than the current received RF power Prf and which provides the highest power conversion efficiency at the current received RF power Prf as the target rectifier. For example, if the received RF power Prf = 5 dBm, rectifier 22c is selected. If the received RF power Prf = 25 dBm, rectifier 22a is selected. In this way, by selecting an appropriate rectifier as the target rectifier according to the current received RF power Prf, high power conversion efficiency can be obtained for a wide range of received RF power Prf.

[0027] Next, we focus on the output load RL as the second parameter that determines the power conversion efficiency of the rectifier. As mentioned earlier, in the evaluation system of Figure 3, the variable resistor 103 is the output load RL. Figure 5 shows the simulation results plotting the relationship between the output load RL and the power conversion efficiency for the rectifier 22b included in the switching rectifier unit 20, using the evaluation system of Figure 3, while fixing the input RF power Pin to constant values ​​of 10 dBm, 15 dBm, and 18 dBm, and varying the output load RL. However, the horizontal axis in Figure 3 is shown as the output voltage Vrec, which uniquely corresponds to the output load RL. The correspondence between the output load RL and the output voltage Vrec is that the output voltage Vrec takes its maximum value when the output load RL is infinite (open circuit), and approaches its minimum value (zero) as the output load RL approaches zero (short circuit).

[0028] As shown in Figure 5, when the input RF power Pin is fixed to a constant value, the power conversion efficiency of the rectifier, i.e., the output power Pout, can be maximized by adjusting the output load RL (output voltage Vrec). In this embodiment 1, the control unit 60 uses the power conversion unit 40 to control the output voltage Vrec of the currently selected target rectifier included in the switching rectifier unit 20, thereby maximizing the output power Pdc1 of the target rectifier.

[0029] For example, if the target rectifier is rectifier 22b and the current received RF power Prf = 15 dBm, then, based on the power conversion characteristics of rectifier 22b shown in Figure 5, the control unit 60 uses the power conversion unit 40 to control the output voltage Vrec of rectifier 22b so that it is approximately 2.8 V. In this way, by controlling the output voltage Vrec of the target rectifier under a given received RF power Prf, the output power Pdc1 of the target rectifier can be maximized.

[0030] (Operation of the power receiving device) The general operation of the power receiving device 100 according to this embodiment 1 is as follows: First, the control unit 60 estimates the current received RF power Prf and selects an appropriate rectifier as the target rectifier according to the current received RF power Prf. Next, the control unit 60 maximizes the output power Pdc1 of the target rectifier by controlling the output voltage Vrec of the target rectifier using the power conversion unit 40. If predetermined conditions are met, such as a fluctuation in the received RF power Prf, the control unit 60 restarts the estimation of the current received RF power Prf.

[0031] Figure 6 is a flowchart illustrating the details of the operation of the power receiving device 100 according to this embodiment 1.

[0032] In step S101, the control unit 60 estimates the current received RF power Prf. Specifically, in order to obtain the output voltage Vrec with the highest possible accuracy while preventing damage to the rectifier, the control unit 60 fixes the input current of the power conversion unit 40 to 0, i.e., the input impedance to infinity (open circuit), and selects the rectifiers 22a to 22c included in the switching rectifier unit 20 in order from the one with the largest maximum input power. The control unit 60 identifies the rectifier whose output voltage Vrec in the open circuit state is less than or equal to the maximum output voltage in the open circuit state (maximum open circuit output voltage), and whose difference between the output voltage Vrec in the open circuit state and the maximum open circuit output voltage of the target rectifier is smallest, i.e., the rectifier from which the output voltage Vrec can be obtained with the highest accuracy, and uses that rectifier to obtain the output voltage Vrec in the open circuit state. A specific method for making the input impedance of the power conversion unit 40 infinite (open circuit) is, for example, in a typical switching regulator circuit used as a DC-DC converter, no input current flows when the switching operation is stopped, and the input side is in an open circuit state, so the output voltage Vrec of the rectifier in the open circuit state can be obtained in this state. The control unit 60 estimates the current received RF power Prf using the relationship between the input power and output voltage when the rectifier output is open, based on the most accurately acquired open-circuit output voltage Vrec.

[0033] In step S102, the control unit 60 determines whether the current received RF power Prf is equal to or greater than the minimum power at which the power receiving device 100 can operate. If the current received RF power Prf is equal to or greater than the minimum power at which it can operate (S102=YES), the control unit 60 proceeds to the processing from step S103 onwards. On the other hand, if the current received RF power Prf is less than the minimum power at which it can operate (S102=NO), the control unit 60 determines that the power supply beam cannot be powered (S110).

[0034] In step S103, the control unit 60 selects one of the rectifiers 22a to 22c included in the switching rectifier unit 20 as the target rectifier, depending on the current received RF power Prf. Specifically, the control unit 60 selects from the rectifiers 22a to 22c the rectifier whose maximum input power is equal to or greater than the current received RF power Prf and which provides the highest power conversion efficiency at the current received RF power Prf. For example, if the current received RF power Prf = 15 dBm, the control unit 60 selects rectifier 22b as the target rectifier based on the power conversion characteristics of each rectifier circuit in Figure 4.

[0035] In step S104, the control unit 60 performs maximum power point control using the currently selected target rectifier. The maximum power point is the output voltage Vrec at which the output power Pdc1 of the rectifier is maximized under a given received RF power Prf. The control unit 60 controls the output voltage Vrec of the target rectifier so that the output voltage Vrec of the target rectifier is located at the maximum power point, that is, so that the output power Pdc1 of the target rectifier is maximized. For example, if the target rectifier is rectifier 22b and the current received RF power Prf = 15 dBm, then, based on the power conversion characteristics of rectifier 22b in Figure 5, the output voltage Vrec of rectifier 22b is controlled to be around 2.8V.

[0036] FIG. 7 is a flowchart for explaining the maximum power point control in step S104 of FIG. 6. Although there are various methods for maximum power point control, in the first embodiment, as an example, the hill-climbing method is adopted. In the hill-climbing method, from the increase or decrease of the output power Pdc1 when the output voltage Vrec of the rectifier is changed as a parameter, the output voltage Vrec at which the output power Pdc1 is maximized, that is, the maximum power point, is searched for.

[0037] In step S401, the control unit 60 determines whether the output voltage Vrec of the target rectifier is less than or equal to the maximum open output voltage of the target rectifier. If the output voltage Vrec is less than or equal to the maximum open output voltage (S401 = YES), the control unit 60 proceeds to the processing after step S402. On the other hand, if the output voltage Vrec is greater than the maximum open output voltage (S401 = NO), the control unit 60 returns to the processing of step S101 in FIG. 6 and reselects the rectifier having a maximum open output voltage greater than that of the current target rectifier as the target rectifier (S101 to S103). In step S402, the control unit 60 acquires the current output power Pdc1 of the target rectifier. In step S403, the control unit 60 attempts to change the output voltage Vrec of the target rectifier by a small amount ΔV by controlling the boost-buck operation of the power conversion unit 40. If the output voltage Vrec can be changed by a small amount ΔV (S404 = YES), the control unit 60 acquires the output power Pdc1* after the output voltage of the target rectifier changes to Vrec + ΔV (S405). On the other hand, if the output voltage Vrec cannot be changed by a small amount ΔV (S404 = NO), the control unit 60 proceeds to the processing of step S107 in FIG. 6.

[0038] In step S406, the control unit 60 determines whether the output power Pdc1* after the voltage change is greater than or equal to the output power Pd1 before the voltage change. If Pdc1* ≥ Pdc1 (S406 = YES), the control unit 60 keeps the sign of the small amount ΔV as it is (S407). On the other hand, if Pdc1* < Pdc1 (S406 = NO), the control unit 60 reverses the sign of the small amount ΔV (S408).

[0039] In step S409, the control unit 60 determines whether the output voltage Vrec of the target rectifier converges to the maximum power point by checking whether the following conditional expression is satisfied.

[0040] |Pdc1*-Pdc1|<ε

[0041] However, in the above equation, ε is a threshold value (a predetermined value) used to determine convergence.

[0042] If the output voltage Vrec of the target rectifier converges to the maximum power point (S409=YES), the control unit 60 proceeds to step S105 in Figure 6. On the other hand, if the output voltage Vrec of the target rectifier does not converge to the maximum power point (S409=NO), the control unit 60 determines whether the condition for discontinuing maximum power point control is met (S410).

[0043] In detail, the control unit 60 checks whether the output power Pd1* of the target rectifier is greater than the maximum output power, and whether the output voltage Vrec of the target rectifier is greater than the maximum open-circuit output voltage. If at least one of these conditions is met, the control unit 60 determines that the termination condition is met. However, the maximum output power is the maximum power that the target rectifier can stably output, and the maximum open-circuit output voltage is the maximum voltage that the target rectifier can output.

[0044] If the condition for discontinuing maximum power point control is met (S410=YES), the control unit 60 discontinues maximum power point control to protect the target rectifier and proceeds to step S101 in Figure 6. On the other hand, if the condition for discontinuing maximum power point control is not met (S410=NO), the control unit 60 updates the current output power Pdc1 to Pdc1* (S411) and returns to step S403.

[0045] In step 105 of Figure 6, the control unit 60 determines whether the current output power Pdc1 of the target rectifier is less than or equal to the maximum output power of the target rectifier.

[0046] If the current output power Pdc1 of the target rectifier is less than or equal to the maximum output power of the target rectifier (S105=YES), the control unit 60 proceeds to step S106. On the other hand, if the current output power Pdc1 of the target rectifier is greater than the maximum output power of the target rectifier (S105=NO), the control unit 60 returns to step S101 and re-selects a rectifier with a greater maximum output power than the current target rectifier as the target rectifier (S101~S103).

[0047] In step S106, the control unit 60 estimates the current received RF power Prf. At this time, since the output voltage Vrec of the target rectifier has converged to the maximum power point (S409=YES) and the current output power Pdc1 of the target rectifier is less than or equal to the maximum output power of the target rectifier (S105=YES), the received RF power Prf can be estimated from the output voltage Vrec or output power Pd1 of the target rectifier.

[0048] In detail, the control unit 60 stores the relationship between the input power and the output voltage or output power at the point of convergence at the maximum power point for each rectifier 22a to 22c included in the switching rectifier unit 20. The control unit 60 refers to these relationships and estimates the current received RF power Prf from the output voltage Vrec or output power Pdc1 of the currently selected target rectifier. The time required for this estimation is extremely fast compared to the process in step S101, which estimates the received RF power Prf while sequentially selecting rectifiers, because it does not require procedures such as switching rectifiers or obtaining open-circuit voltages.

[0049] Once the current received RF power Prf is estimated, the control unit 60 re-selects a rectifier as the target rectifier whose maximum input power is equal to or greater than the current received RF power Prf and which provides the highest power conversion efficiency at the current received RF power Prf (S103). This allows the system to quickly track relatively small fluctuations in the received RF power Prf and select the optimal rectifier as the target rectifier.

[0050] In step S107, the control unit 60 determines whether the current received RF power Prf is equal to or greater than the minimum power (minimum input power) at which the target rectifier can operate stably. Specifically, if the received RF power Prf fluctuates and falls below the minimum input power of the target rectifier, the output power Pdc1 of the target rectifier will fall below the minimum power (minimum output power) at which the target rectifier can output stably. In addition, the output power Pdc1 and output voltage Vrec of the target rectifier fluctuate depending on the output load conditions of the target rectifier, but when the output load conditions are light load, the output voltage Vrec tends to represent a voltage corresponding to the received RF power Prf more accurately than the output power Pdc1.

[0051] Utilizing this property, the control unit 60 determines whether the current received RF power Prf is equal to or greater than the minimum input power of the target rectifier by checking whether the output voltage Vrec of the target rectifier is equal to or greater than the minimum output voltage of the target rectifier. Note that if the current received RF power Prf is less than the minimum input power of the rectifier, the output power Pdc1 of the rectifier will also be less than the minimum output power. Therefore, the control unit 60 may determine whether the current received RF power Prf is equal to or greater than the minimum input power of the target rectifier by checking the output power Pdc1 instead of the output voltage Vrec. However, it is more preferable to check the output voltage Vrec of the target rectifier in step S107 because it is easier to distinguish from the light load state described later.

[0052] If the current received RF power Prf is less than the minimum input power of the target rectifier (S107=NO), the control unit 60 returns to step S101 and re-selects a rectifier as the target rectifier whose minimum input power is lower than the current received RF power Prf (S101~S103). On the other hand, if the current received RF power Prf is equal to or greater than the minimum input power of the currently selected target rectifier (S107=YES), the control unit 60 proceeds to steps S108~S109.

[0053] In steps S108 to S109, a light load state is detected and a transition from normal mode to light load mode is determined. If the charge level of the energy storage unit 50 has reached near its upper limit, but the output power Pdc2 of the power conversion unit 40 exceeds the power required by the external load 80, the power conversion unit 40 will be unable to output an output power Pdc2 that corresponds to the output power Pdc1 at the time of convergence to the maximum power point of the target rectifier. This state is called a light load state. In this embodiment 1, when such a light load state is detected, the system transitions from normal mode to light load mode and remains in light load mode until the light load state is resolved. Once the light load state is resolved, the system returns from light load mode to normal mode. In detail, the following processes are executed.

[0054] In step S108, the control unit 60 determines whether the system is already in light-load mode. If it is already in light-load mode (S108=YES), the control unit 60 returns to the process in step S103. This maintains the light-load state, and the processes in steps S103-S104 and S107-S108 are repeated until the output voltage Vrec of the target rectifier converges to the maximum power point. After that, when the light-load state is resolved and the output voltage Vrec of the target rectifier converges to the maximum power point (S409=YES), the system automatically returns from light-load mode to normal mode, and the processes from step S105 onward are executed.

[0055] On the other hand, if the system is not currently in light-load mode (S108=NO), the control unit 60 determines whether to switch to light-load mode (S109). Specifically, the control unit 60 estimates the current received RF power Prf using the same method as in steps S101 to S103, and re-selects the target rectifier according to the received RF power Prf. If the target rectifier before and after re-selection is the same, the control unit 60 determines that the cause of the cancellation of maximum power point control is not a fluctuation in the received RF power Prf, but a light-load state, and switches to light-load mode (S109=YES). On the other hand, if the target rectifier before and after re-selection is different, the control unit 60 determines that the cause of the cancellation of maximum power point control is not a light-load state, but a fluctuation in the received RF power Prf, and does not switch to light-load mode (S109=NO).

[0056] As described above, the control unit 60 of the power receiving device 100 according to this embodiment 1 estimates the received RF power Prf based on the output voltage Vrec or output power Pdc1 of the currently selected target rectifier included in the switching rectifier unit 20 and the relationship between the input power and output voltage or output power of the target rectifier. Due to these features, the power receiving device 100 according to this embodiment 1 can estimate the received RF power Prf during a series of operations in which it receives the received RF power Prf and converts it to DC power Pdc2 for output.

[0057] The control unit 60 selects one of the rectifiers 22a to 22c included in the switching rectifier section as the target rectifier, according to the received RF power Prf estimated as described above. Specifically, the control unit 60 selects from among the rectifiers 22a to 22c as the target rectifier, which has a maximum input power equal to or greater than the received RF power Prf and provides the highest power conversion efficiency at that received RF power Prf. This makes it possible to always obtain a large output power Pdc2 from the received RF power Prf, which fluctuates over a wide range of magnitudes.

[0058] The control unit 60 uses the power conversion unit 40 to control the output voltage Vrec of the target rectifier so that the output power Pdc1 of the target rectifier is maximized. This makes it possible to always obtain the maximum output power Pdc2 from the received RF power Prf, which fluctuates over a wide range of magnitudes.

[0059] If the output voltage Vrec of the target rectifier is converging to the maximum power point, and the output power Pdc1 of the target rectifier is less than or equal to the maximum output power of the target rectifier (S105=YES), the control unit 60 estimates the received RF power Prf using the relationship between the input power and the output voltage or output power when the target rectifier is converging to the maximum power point. This allows for faster estimation of the received RF power Prf compared to the method described below, especially in the case of relatively small fluctuations in the received RF power Prf.

[0060] In cases other than those described above, i.e., when maximum power point control is interrupted due to fluctuations in the received RF power Prf (S107=NO, S109=NO), or when the power is converging to the maximum power point but the output power Pdc1 of the target rectifier is greater than the maximum output power (S105=NO), the control unit 60 fixes the input impedance of the power conversion unit 40 to infinity (open circuit), selects the rectifiers 22a to 22c included in the switching rectifier unit 22 in order from the one with the largest maximum input power, and estimates the received RF power Prf using the relationship between the input power and output voltage when the output of each rectifier is open circuit. This prevents the rectifier from being damaged by power exceeding the maximum input power, even when the magnitude of the received RF power Prf is unknown.

[0061] [Embodiment 2] Figure 8 shows a detailed configuration of the switching rectifier unit 220 of the power receiving device according to Embodiment 2. The switching rectifier unit 220 has reverse current preventers 224a to 224c added between each output of the rectifiers 22a to 22c and node 23. Note that the configuration other than the switching rectifier unit 220 is the same as that of the power receiving device 100 of Embodiment 1.

[0062] In the switching rectifier unit 20 of Embodiment 1, each output of rectifiers 22a to 22c is always connected to node 23. Therefore, the output current of the currently selected target rectifier may flow back through node 23 to the output of other unselected rectifiers, potentially damaging the rectifiers. In the switching rectifier unit 220 of Embodiment 2, reverse current preventers 224a to 224c are provided between each output of rectifiers 22a to 22c and node 23, thereby preventing the output current from flowing back from node 23 to rectifiers 22a to 22c.

[0063] For example, the reverse current blockers 224a to 224c may be DC switches that, by referring to the Ist1 command signal input from the control unit 60 to the RF switch 21, disconnect the connection between the output of a rectifier that is not currently selected and node 23. Alternatively, the reverse current blockers 224a to 224c may be disconnection circuits that, when they detect that the output voltage of the rectifier to which they are connected is lower than the voltage of node 23, disconnect the connection between the rectifier and the node.

[0064] [Embodiment 3] Figure 9 shows a detailed configuration of the power conversion unit 340 according to Embodiment 3. The power conversion unit 340 includes a DC switch 341 (second switching unit), three DC-DC converter circuits 342a to 342c (power conversion circuits) that differ in at least one of their circuit configurations and circuit constants, a DC voltage sensor 344 (voltage detection unit), and a selection control unit 345. However, the number of DC-DC converter circuits is not limited to three; there may be multiple. In addition, the configuration other than the power conversion unit 340 is the same as that of the power receiving device 100 in Embodiment 1.

[0065] The DC switch 341 connects the input of the power conversion unit 340 to the input of one of the DC-DC converter circuits selected by the selection control unit 345. The outputs of the DC-DC converter circuits 342a to 342c are connected together at node 343 (second combining unit) to become the output of the power conversion unit 340. The DC voltage sensor 344 detects the output voltage of the power conversion unit 340.

[0066] The selection control unit 345 is composed of a microcomputer, FPGA, or ASIC, etc. The selection control unit 345 selects the DC-DC converter circuit with the highest power conversion efficiency from among the DC-DC converter circuits 342a to 342c, based on the relationship between the output voltage Vrec of the currently selected target rectifier included in the command signal Ist2 from the control unit 60 and the output voltage of the power conversion unit 340. The selection control unit 345 controls the operation of the selected DC-DC converter circuit according to the command signal Ist2 from the control unit 60.

[0067] Generally, the power conversion efficiency of a DC-DC converter circuit depends on the circuit configuration and circuit constants. For example, a DC-DC converter circuit specialized in either boosting or bucking has higher power conversion efficiency than a DC-DC converter circuit capable of both boosting and bucking. Also, the input voltage of the DC-DC converter circuit, i.e., the output voltage Vrec of the target rectifier, fluctuates due to maximum power point control. On the other hand, the output voltage of the DC-DC converter circuit, i.e., the output voltage of the power conversion unit 40, is fixed to the closed-circuit voltage (CCV) of the energy storage unit 50, which is determined according to the amount of charge in the energy storage unit 50.

[0068] In this third embodiment, the DC-DC converter circuit with the highest power conversion efficiency is selected from among a plurality of DC-DC converter circuits 342a to 342c, each having at least one different circuit configuration and circuit constants, according to the relationship between the input voltage and output voltage of the power conversion unit 340. This makes it possible to obtain high power conversion efficiency under various conditions. Furthermore, the power conversion efficiency of the DC-DC converter circuit also depends on the input power. Therefore, the selection control unit 345 may also consider the output power Pdc1 of the target rectifier in addition to the relationship between the input voltage and output voltage when selecting the DC-DC converter circuit.

[0069] [Embodiment 4] Figure 10 shows the configuration of a wireless power supply system according to Embodiment 4. The wireless power supply system includes one or more power transmission devices 401 and one or more power receiving devices 400. However, only one power transmission device 401 and one power receiving device 400 are shown in Figure 10.

[0070] The power transmission device 401 includes a power transmission unit 402 that transmits a power supply beam, a wireless communication unit 403 (second wireless communication unit) that transmits and receives wireless signals with the power receiving device 400, and a control unit 404 (second control unit) that controls the operation of the power transmission unit 402 and the wireless communication unit 403. The power receiving device 400 includes, in addition to the configuration of the power receiving device 100 of Embodiment 1, a wireless communication unit 470 (first wireless communication unit) that transmits and receives wireless signals with the power transmission device 401. The control unit 460 (first control unit) of the power receiving device 400 controls the operation of the wireless communication unit 470 in addition to the switching rectifier unit 20 and the power conversion unit 40.

[0071] The frequency of wireless communication between the power transmission device 401 and the power receiving device 400 is preferably different from the frequency of the power supply beam, but this does not preclude the use of the same frequency or a nearby frequency. Furthermore, the frequency of wireless communication may conform to general wireless communication standards.

[0072] The wireless transmitter 470 of the power receiving device 400 wirelessly transmits control information to the power transmitting device 401. The control information includes at least one of the following: the power received RF power Prf, the output power Pd1 of the currently selected target rectifier, the output voltage Vrec of the target rectifier, the output current Irec of the target rectifier, the output power Pdc2 of the power conversion unit 40, the power charged and discharged to the energy storage unit 50, the amount of charge in the energy storage unit 50, and command signals Ist1 and Ist2.

[0073] The control unit 404 of the power transmission device 401 receives control information from the power receiving device 400 via the wireless communication unit 403, and based on the received control information, performs actions such as starting and ending power supply to the power receiving device 400, and controlling the size and direction of the power supply beam. Furthermore, if control information is received from multiple power receiving devices, the control unit 404 of the power transmission device 401 can optimize the entire wireless power supply system by adjusting the allocation of power supply time to each power receiving device based on the multiple pieces of received control information.

[0074] Furthermore, the control unit 404 of the power transmission unit 401 may be responsible for some of the functions that the control unit 460 of the power receiving unit 400 is responsible for. For example, the power transmission unit 401 may perform tasks such as estimating the RF power received power Prf, selecting the target rectifier, and calculating the maximum power point control based on control information received from the power receiving unit 400, and remotely control the power receiving unit 400 by wirelessly transmitting a command signal from the power transmission unit 401 to the power receiving unit 400.

[0075] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the embodiments. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the embodiments. These embodiments and their variations are included in the scope and spirit of the embodiments, as well as in the claims and their equivalents.

[0076] Furthermore, this embodiment can also be configured as follows. [Item 1] (Example 1) A power receiving unit that receives wireless power, A switching rectifier unit that rectifies the received power of the wireless power by a target rectifier which is one rectifier selected from among the multiple rectifiers, which includes a plurality of rectifiers with different power conversion characteristics, A detection unit for detecting the output voltage or output power of the target rectifier, A power conversion unit that controls the output voltage of the target rectifier, A power storage unit that charges and discharges the output power of the power conversion unit, A control unit that estimates the received power based on the output voltage of the target rectifier and information showing the relationship between the input power and output voltage of the target rectifier, or based on the output power of the target rectifier and information showing the relationship between the input power and output power of the target rectifier, and controls the operation of the switching rectifier unit and the power conversion unit based on the estimated received power, A power receiving device equipped with a power receiving system. [Item 2] (Example 1) The control unit selects one of the plurality of rectifiers as the target rectifier according to the received power. The power receiving device described in item 1. [Item 3] (Example 1) The control unit selects from among the plurality of rectifiers the rectifier whose maximum input power is equal to or greater than the received power and which can obtain the highest power conversion efficiency at the received power as the target rectifier. The power receiving device described in item 2. [Item 4] (Example 1) The control unit controls the step-up / step-down operation of the power conversion unit, thereby controlling the output voltage of the target rectifier so that the output power of the target rectifier is maximized. A power receiving device as described in any one of items 1 to 3. [Item 5] (Example 1) The control unit estimates the received power using information indicating the relationship between the input power and output power or output power at the time of convergence to the maximum power point of the target rectifier, or using information indicating the relationship between the input power and output power at the time of convergence to the maximum power point of the target rectifier. The power receiving device described in item 4. [Item 6] (Example 1) The control unit, with the input current of the power conversion unit in an open state, selects the plurality of rectifiers in order from the one with the largest maximum input power, and estimates the received power using information showing the relationship between the input power and output voltage when the outputs of the plurality of rectifiers are open. A power receiving device as described in any one of items 1 to 5. [Item 7] (Example 1) The system further includes a calculation unit that measures the power being charged and discharged to the energy storage unit and calculates the amount of charge in the energy storage unit based on the measured power. The power receiving device according to claim 1. [Item 8] (Example 1) The switching rectifier section is, A first switching unit that connects the input of the switching rectifier unit to the input of any one of the plurality of rectifiers, The outputs of the plurality of rectifiers are all connected together, and a first combining unit is connected to the output of the switching rectifier unit, Includes, The control unit selects one of the plurality of rectifiers as the target rectifier by controlling the first switching unit. A power receiving device as described in any one of items 1 to 7. [Item 9] (Example 2) The switching rectifier further includes a plurality of backflow preventers provided between each output of the plurality of rectifiers and the first combining unit, The power receiving device described in item 8. [Item 10] (Example 3) The power conversion unit is Multiple power conversion circuits that differ in at least one of their circuit configurations and circuit constants, A second switching unit connects the input of the power conversion unit to the input of any one of the multiple power conversion circuits, The outputs of the plurality of power conversion circuits are connected together, and a second combining unit is connected to the output of the power conversion unit, A voltage detection unit for detecting the output voltage of the power conversion unit, A selection control unit that controls the second switching unit to select one of the plurality of power conversion circuits, Includes, The selection control unit selects from among the plurality of power conversion circuits the power conversion circuit with the highest power conversion efficiency in relation to the output voltage of the target rectifier and the output voltage of the power conversion unit. The power receiving device described in item 1. [Item 11] (Example 4) The system further includes a wireless communication unit that wirelessly transmits control information to a power transmission device that transmits wireless power, including the operating status of the power receiving device. The power receiving device described in item 1. [Item 12] (Example 4) The control information is, The estimated value of the received power, The output power of the target rectifier, The output voltage of the target rectifier The output current of the aforementioned rectifier, The output power of the power conversion unit, Information for controlling the switching rectifier unit, which is input from the control unit to the switching rectifier unit, and Information for controlling the power conversion unit is input from the control unit to the power conversion unit. including at least one of the following: The power receiving device described in item 11. [Item 13] (Example 4) The system further includes a calculation unit that measures the power being charged and discharged to the energy storage unit and calculates the amount of charge in the energy storage unit based on the measured power. The control information further includes at least one of the power charged and discharged to the energy storage unit and the amount of charge in the energy storage unit. The power receiving device described in item 12.

[14] (Method Claim) A method for receiving wireless power, Receiving wireless power, The received power of the wireless power is rectified by a target rectifier, which is a single rectifier selected from among several rectifiers with different power conversion characteristics. The output voltage or output power of the target rectifier is detected, Based on the output voltage of the target rectifier and information showing the relationship between the input power and output voltage of the target rectifier, or based on the output power of the target rectifier and information showing the relationship between the input power and output power of the target rectifier, the received power is estimated. Based on the estimated power received, the target rectifier is selected. A method of receiving power, including the method of receiving power. [Item 15] (Example 4) (System Claim) A power transmission device that transmits wireless power, A power receiving device that receives the aforementioned wireless power, Includes, The power receiving device is A power receiving unit that receives the aforementioned wireless power, A switching rectifier unit that rectifies the received power of the wireless power by a target rectifier which is one rectifier selected from among the multiple rectifiers, which includes a plurality of rectifiers with different power conversion characteristics, A detection unit for detecting the output voltage or output power of the target rectifier, A power conversion unit that controls the output voltage of the target rectifier, A power storage unit that charges and discharges the output power of the power conversion unit, A first control unit that estimates the received power based on the output voltage of the target rectifier and information showing the relationship between the input power and output voltage of the target rectifier, or based on the output power of the target rectifier and information showing the relationship between the input power and output power of the target rectifier, and controls the operation of the switching rectifier unit and the power conversion unit based on the estimated received power, A wireless power supply system equipped with [features / equipment].

[16] (Example 4)(System Claim) The power receiving device is It further includes a first wireless communication unit that transmits and receives wireless signals, The first control unit further controls the operation of the first wireless communication unit. The aforementioned power transmission device is A power transmission unit that transmits the aforementioned wireless power, A second wireless communication unit that transmits and receives wireless signals, A second control unit that controls the operation of the power transmission unit and the second wireless communication unit, Equipped with, The first wireless communication unit of the power receiving device wirelessly transmits control information indicating the operating status of the power receiving device to the power transmitting device. The second control unit of the power transmission device controls the power transmission unit based on the control information. The power supply system described in item 15.

[17] (Example 4)(System Claim) The second control unit of the power transmission device generates information to control the operation of the switching rectifier and the power conversion unit in accordance with the control information received from the power receiving device, and remotely controls the power receiving device by wirelessly transmitting a command signal containing the generated information to the power receiving device. The power supply system described in item 16. [Explanation of Symbols]

[0077] 10 RF Power Receiving Unit (Power Receiving Unit) 20 Switching rectifier 21 RF switch (first switching section) 22a rectifier 22b rectifier 22c rectifier 23 Nodes (First Synthesis Unit) 30 Detection unit 40 Power Conversion Unit 50. Energy storage amount calculation unit (calculation unit) 51 Monitoring Department 60 Control Unit 80 External load 100 Power receiving device 220 Switching rectifier 224a Backflow preventer 224b Backflow preventer 224c Backflow preventer 340 Power Conversion Unit 341 DC switch (second switching section) 342a DC-DC converter circuit (power conversion circuit) 342b DC-DC converter circuit (power conversion circuit) 342c DC-DC converter circuit (power conversion circuit) 343 Node (Second Synthesis Unit) 344 DC voltage sensor (voltage detection unit) 345 Selection Control Unit 400 Power receiving device 401 Power transmission equipment 402 RF Transmission Unit (Transmission Unit) 403 Radio Communication Section (2nd Radio Communication Section) 404 Control Unit (Second Control Unit) 460 Control Unit (First Control Unit) 470 Radio Communication Section (1st Radio Communication Section) Irec rectifier output current Ist1 Command signal (1st command signal) Ist2 command signal (second command signal) Output power of Pdc1 rectifier Output power of the Pdc2 power conversion unit Prf Received RF Power Vrec rectifier output voltage

Claims

1. A power receiving unit that receives wireless power, A switching rectifier unit that rectifies the received power of the wireless power by a target rectifier which is one rectifier selected from among the multiple rectifiers, which includes a plurality of rectifiers with different power conversion characteristics, A detection unit for detecting the output voltage or output power of the target rectifier, A power conversion unit that controls the output voltage of the target rectifier, A power storage unit that charges and discharges the output power of the power conversion unit, A control unit that estimates the received power based on the output voltage of the target rectifier and information showing the relationship between the input power and output voltage of the target rectifier, or based on the output power of the target rectifier and information showing the relationship between the input power and output power of the target rectifier, and controls the operation of the switching rectifier unit and the power conversion unit based on the estimated received power, A power receiving device equipped with a power receiving system.

2. The control unit selects one of the plurality of rectifiers as the target rectifier according to the received power. The power receiving device according to claim 1.

3. The control unit selects from among the plurality of rectifiers the rectifier whose maximum input power is equal to or greater than the received power and which can obtain the highest power conversion efficiency at the received power as the target rectifier. The power receiving device according to claim 2.

4. The control unit controls the step-up / step-down operation of the power conversion unit, thereby controlling the output voltage of the target rectifier so that the output power of the target rectifier is maximized. The power receiving device according to claim 1.

5. The control unit estimates the received power using information indicating the relationship between the input power and output power at the time of convergence to the maximum power point of the target rectifier, or using information indicating the relationship between the input power and output power at the time of convergence to the maximum power point of the target rectifier, when the output voltage of the target rectifier is converged to the maximum power point of the target rectifier. The power receiving device according to claim 4.

6. The control unit, with the input current of the power conversion unit in an open state, selects the plurality of rectifiers in order from the one with the largest maximum input power, and estimates the received power using information showing the relationship between the input power and output voltage when the outputs of the plurality of rectifiers are open. The power receiving device according to claim 1.

7. The system further includes a calculation unit that measures the power being charged and discharged to the energy storage unit and calculates the amount of charge in the energy storage unit based on the measured power. The power receiving device according to claim 1.

8. The switching rectifier section is, A first switching unit that connects the input of the switching rectifier unit to the input of any one of the plurality of rectifiers, The outputs of the plurality of rectifiers are all connected together, and a first combining unit is connected to the output of the switching rectifier unit, Includes, The control unit selects one of the plurality of rectifiers as the target rectifier by controlling the first switching unit. The power receiving device according to claim 1.

9. The switching rectifier further includes a plurality of reverse current preventers provided between each output of the plurality of rectifiers and the first combining unit, The power receiving device according to claim 8.

10. The power conversion unit is Multiple power conversion circuits having different circuit configurations and circuit constants, A second switching unit connects the input of the power conversion unit to the input of any one of the multiple power conversion circuits, The outputs of the aforementioned multiple power conversion circuits are all connected to a second combining unit which is connected to the output of the power conversion unit, A voltage detection unit for detecting the output voltage of the power conversion unit, A selection control unit that controls the second switching unit to select one of the plurality of power conversion circuits, Includes, The selection control unit selects from among the plurality of power conversion circuits the power conversion circuit with the highest power conversion efficiency in relation to the output voltage of the target rectifier and the output voltage of the power conversion unit. The power receiving device according to claim 1.

11. The system further includes a wireless communication unit that wirelessly transmits control information to a power transmission device that transmits wireless power, including the operating status of the power receiving device. The power receiving device according to claim 1.

12. The control information is, The estimated value of the received power, The output power of the target rectifier, The output voltage of the target rectifier, The output current of the aforementioned rectifier, The output power of the power conversion unit, Information for controlling the switching rectifier unit, which is input from the control unit to the switching rectifier unit, and Information for controlling the power conversion unit is input from the control unit to the power conversion unit. Including at least one of the following: The power receiving device according to claim 11.

13. The system further includes a calculation unit that measures the power being charged and discharged to the energy storage unit and calculates the amount of charge in the energy storage unit based on the measured power. The control information further includes at least one of the power charged and discharged to the energy storage unit and the amount of charge in the energy storage unit. The power receiving device according to claim 12.

14. A method for receiving wireless power, Receiving wireless power, The received power of the wireless power is rectified by a target rectifier, which is a single rectifier selected from among several rectifiers with different power conversion characteristics. The output voltage or output power of the target rectifier is detected, Based on the output voltage of the target rectifier and information showing the relationship between the input power and output voltage of the target rectifier, or based on the output power of the target rectifier and information showing the relationship between the input power and output power of the target rectifier, the received power is estimated. Based on the estimated power received, the target rectifier is selected. Method of receiving power.

15. A power transmission device that transmits wireless power, A power receiving device that receives the aforementioned wireless power, Includes, The power receiving device is A power receiving unit that receives the aforementioned wireless power, A switching rectifier unit that rectifies the received power of the wireless power by a target rectifier which is one rectifier selected from among the multiple rectifiers, which includes a plurality of rectifiers with different power conversion characteristics, A detection unit for detecting the output voltage or output power of the target rectifier, A power conversion unit that controls the output voltage of the target rectifier, A power storage unit that charges and discharges the output power of the power conversion unit, A first control unit that estimates the received power based on the output voltage of the target rectifier and information showing the relationship between the input power and output voltage of the target rectifier, or based on the output power of the target rectifier and information showing the relationship between the input power and output power of the target rectifier, and controls the operation of the switching rectifier unit and the power conversion unit based on the estimated received power, A wireless power supply system equipped with [features / equipment].

16. The power receiving device is It further includes a first wireless communication unit that transmits and receives wireless signals, The first control unit further controls the operation of the first wireless communication unit, The aforementioned power transmission device is A power transmission unit that transmits the aforementioned wireless power, A second wireless communication unit that transmits and receives wireless signals, A second control unit that controls the operation of the power transmission unit and the second wireless communication unit, Equipped with, The first wireless communication unit of the power receiving device wirelessly transmits control information indicating the operating status of the power receiving device to the power transmitting device. The second control unit of the power transmission device controls the power transmission unit based on the control information. The power supply system according to claim 15.

17. The second control unit of the power transmission device generates information to control the operation of the switching rectifier and the power conversion unit in accordance with the control information received from the power receiving device, and remotely controls the power receiving device by wirelessly transmitting a command signal containing the generated information to the power receiving device. The power supply system according to claim 16.

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