Wireless power transmission system, wireless power transmission circuit, and wireless power reception circuit

Abstract

A wireless power transmission system is provided with: a wireless power transmission circuit provided with an inverter (2) including a first LC resonance circuit (21) including a power transmission inductor (Lt), and a wireless power reception circuit provided with a second LC resonance circuit (21) including a power transmission inductor (Lt); an inverter (2) switches an input voltage at a predetermined switching frequency and a predetermined duty ratio, and transmits an AC voltage obtained by the switching from a power transmission inductor (Lt). A wireless power receiving circuit is provided with: a rectifying circuit (3) including a second LC resonance circuit (31) including a power receiving inductor (Lr) electromagnetically coupled to a power transmission inductor (Lt), the rectifying circuit (3) rectifying an AC voltage received by the power receiving inductor and outputting a rectified voltage; and a regulator (4) that detects the output voltage from the regulator (4), controls the rectified voltage so that the output voltage becomes a predetermined voltage on the basis of the detected output voltage, and outputs the output voltage.

Description

Technical Field

[0001] The present invention relates to a wireless power transmission system including a wireless power transmission circuit and a wireless power receiving circuit that are electromagnetically coupled, a wireless power transmission circuit used in the wireless power transmission system, and a wireless power receiving circuit used in the wireless power transmission system. Background Art

[0002] Conventionally, mobile vehicles such as wireless transport vehicles (AGVs (Automatic Guided Vehicles)) and electric vehicles (EVs (Electric Vehicles)) are equipped with rechargeable batteries such as lithium-ion batteries. When charging the rechargeable batteries, after the AGV is moved to a charging station, the power receiving coil mounted on the AGV is electromagnetically coupled with the power transmission coil of the charging station, and non-contact charging is performed in a non-contact charging system.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-022804

[0004] Non-patent document 1: Samer Aldhaher, et al., "Load-Independent Class E / EFInverters and Rectifiers for MHz-Switching Applications," IEEE Transactions on Power Electronics, Vol. 33, No. 10, October 2018. Summary of the invention

[0005] Technical problem to be solved by the invention

[0006] As described above, the power receiving coil and the power transmitting coil are electromagnetically coupled to perform contactless charging, but there are the following changing factors.

[0007] (Change Factor A) When the remaining charge level of the rechargeable battery or the operation of a device serving as a load changes, the load changes.

[0008] (Variation Factor B) The coupling degree k between the power transmission and receiving coils changes according to the positional deviation between the coils.

[0009] That is, there is a technical problem that it is difficult to change the output characteristics of voltage or current, and it is difficult to realize soft switching such as zero voltage switching (ZVS) and zero current switching (ZCS).

[0010] In order to solve this technical problem, in FIG. 32 of non-patent document 1 (the present application Figure 6), as described later in "The inventor's view", by combining the E-class inverter and the rectifier circuit, the output voltage can be made constant and the soft switching can be realized in "variation factor A", and the soft switching can be realized in "variation factor B", but there is a technical problem that the output voltage cannot be made constant. In other words, there is a technical problem that the output characteristics of the voltage or current will change with the change of the coupling degree k.

[0011] The object of the present invention is to provide a wireless power transmission system, a wireless power transmission circuit and a wireless power receiving circuit used in the wireless power transmission system, which can solve the technical problems of the prior art and make the output voltage or output current constant relative to the change of the coupling degree k.

[0012] Solutions for solving technical problems

[0013] A wireless power transmission system according to a first aspect of the present invention includes a wireless power transmission circuit and a wireless power reception circuit.

[0014] The wireless power transmission circuit includes an inverter.

[0015] The inverter includes a first LC resonant circuit, the first LC resonant circuit includes a power transmission inductor, the inverter switches an input voltage at a predetermined switching frequency and a predetermined duty cycle, and transmits an AC voltage obtained by switching from the power transmission inductor,

[0016] The wireless power receiving circuit comprises:

[0017] a rectifier circuit including a second LC resonant circuit including a power receiving inductor electromagnetically coupled to the power transmitting inductor, the rectifier circuit rectifying an AC voltage received by the power receiving inductor and outputting a rectified voltage; and

[0018] The first regulator detects an output voltage from the first regulator, controls the rectified voltage based on the detected output voltage so that the output voltage becomes a predetermined voltage, and outputs the output voltage.

[0019] A wireless power transmission system according to a second aspect of the present invention is, in the wireless power transmission system according to the first aspect,

[0020] The wireless power transmission circuit further includes a second regulator, which is disposed in the front section of the inverter.

[0021] The second regulator includes a second current control transistor,

[0022] The second regulator has the following operation modes:

[0023] (A) a constant current mode, detecting an output current from the second regulator, controlling the second current control transistor based on the detected output current, thereby controlling the input voltage in such a manner that the output current becomes a predetermined current, and outputting the output current to the inverter; and

[0024] (B) a constant time ratio mode, controlling the input voltage by controlling the second current control transistor at a constant duty ratio, and outputting the output voltage to the inverter,

[0025] The first regulator has an operation mode of a constant current mode in addition to the constant voltage mode (A).

[0026] The (A) constant voltage mode detects the output voltage from the first regulator, controls the rectified voltage so that the output voltage becomes a predetermined voltage based on the detected output voltage, and outputs the output voltage.

[0027] The (B) constant current mode detects an output current from the first regulator, controls the rectified voltage based on the detected output current so that the output current becomes a predetermined current, and outputs the output voltage,

[0028] The first regulator further includes a first communication circuit.

[0029] When selectively switching between the constant voltage mode and the constant current mode, the first communication circuit sends an operation mode switching signal to the second regulator, or receives an operation mode switching signal from the second regulator.

[0030] The second regulator further includes a second communication circuit.

[0031] When selectively switching between the constant time ratio mode and the constant current mode, the second communication circuit sends an operation mode switching signal to the first regulator, or receives an operation mode switching signal from the first regulator.

[0032] The wireless power transmission system is configured such that when the first regulator operates in the constant voltage mode, the second regulator operates in the constant time ratio mode.

[0033] And when the first regulator operates in the constant current mode, the second regulator operates in the constant current mode.

[0034] Effects of the Invention

[0035] Therefore, according to the wireless power transmission system of the present invention, it is possible to keep the output voltage or the output current constant despite the variation in the coupling degree k. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a circuit diagram showing a configuration example of the wireless power transmission system according to the first embodiment.

[0037] Figure 2 This is a circuit diagram showing a configuration example of a wireless power transmission system according to the second embodiment.

[0038] Figure 3 This is an equivalent circuit diagram for explaining the case where the output voltage can be made constant in the first embodiment.

[0039] Figure 4A It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2A according to a first modification of the inverter 2 is shown.

[0040] Figure 4B It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2B according to a second modification of the inverter 2.

[0041] Figure 4C It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2C according to a third modification of the inverter 2 is shown.

[0042] Figure 4D It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2D according to a fourth modification of the inverter 2 is shown.

[0043] Figure 4E It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2E according to a fifth modification of the inverter 2 is shown.

[0044] Figure 4F It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2F according to a sixth modification of the inverter 2 is shown.

[0045] Figure 4G It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2G according to a seventh modification of the inverter 2 is shown.

[0046] Figure 5A It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3A according to a first modification of the rectifier circuit 3 is shown.

[0047] Figure 5B It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3B according to a second modification of the rectifier circuit 3 is shown.

[0048] Figure 5C It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3C according to a third modification of the rectifier circuit 3.

[0049] Figure 5D It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3D according to a fourth modification of the rectifier circuit 3 is shown.

[0050] Figure 5E It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3E according to a fifth modification of the rectifier circuit 3 is shown.

[0051] Fig. 5F It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3F according to a sixth modification of the rectifier circuit 3 is shown.

[0052] Figure 6 1 is a circuit diagram showing a configuration of a load-independent synchronous class E rectifier circuit for a wireless power transmission system according to Conventional Example 1 disclosed in Non-Patent Document 1.

[0053] Figure 7 1 is a circuit diagram showing a configuration of a load-independent synchronous EF class inverter for a wireless power transmission system according to Conventional Example 2 disclosed in Non-Patent Document 1. DETAILED DESCRIPTION

[0054] Hereinafter, embodiments and modifications of the present invention will be described with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or similar components.

[0055] (Opinion of the inventor)

[0056] Figure 6 32 of Non-Patent Document 1 is a circuit diagram showing the structure of a load-independent synchronous class E rectifier circuit for a wireless power transmission system according to Conventional Example 1. Figure 6The load-independent synchronous type E-class rectifier circuit is composed of a series inductor Ls, a resonant capacitor Cres, a switching MOS field effect transistor (hereinafter referred to as a switching MOS transistor) Q51, and an inductor L51 and a capacitor C51, C DC Here, "load independence" means that even if the resistance value or impedance value of the load connected to the output of the circuit, such as a secondary battery, changes, the output characteristics of the circuit (voltage, current or power) remain constant. Due to this load independence, soft switching can be achieved without being restricted by the load.

[0057] In the above-constructed Figure 6 In the rectifier circuit, the induced AC voltage is applied to the series inductor Ls, and the gate control voltage v gs5 After being switched and rectified by the switching MOS transistor Q51, the current is fed to the load resistor R L The rectified DC voltage Vout is output.

[0058] Figure 7 17 of Non-Patent Document 1 shows a circuit diagram showing a configuration of a load-independent synchronous EF class inverter for a wireless power transmission system according to Conventional Example 2 disclosed in FIG. 17 of Non-Patent Document 1. FIG. Figure 7 The EF class inverter is configured to include a switching MOS transistor Q61, an input inductor L61, capacitors C61, C62, C63, Cs, and inductors L62, L63, Ls. Here, the capacitors C62, C63 and the inductors L62, L63 form a first LC resonance circuit having a predetermined resonance frequency, and the inductor Ls and the capacitor Cs form a second LC resonance circuit having a predetermined resonance frequency.

[0059] In the above-constructed Figure 7 In the inverter, the AC voltage is applied to the switching MOS transistor Q61 through the input inductor L61, and the gate control voltage v gs6 After being switched by the switching MOS transistor Q61 and filtering only the predetermined resonant frequency component in the resonant circuit, the load resistor R L Output filtered AC voltage.

[0060] As from Figure 6 as well as Figure 7As clearly stated, by combining the E-class inverter and the rectifier circuit, the output voltage can be made constant and the soft switching can be achieved relative to the change of the load (change factor A), and although the soft switching can be achieved relative to the coupling degree k (change factor B), there is a technical problem that the output voltage cannot be made constant. That is, there is a technical problem that the output characteristics of the voltage or current will change relative to the change of the coupling degree k. In an embodiment of the present invention, a wireless power transmission system is proposed that can make the output voltage or output current constant relative to the change of the coupling degree k.

[0061] (Implementation Method 1)

[0062] Figure 1 is a circuit diagram showing a configuration example of a wireless power transmission system according to Embodiment 1. Figure 1 In the wireless power transmission system, an inverter 2, a rectifier circuit 3, and a post regulator 4 are provided. Here, the inverter 2 constitutes a "wireless power transmission circuit", and the rectifier circuit 3 and the post regulator 4 constitute a "wireless power reception circuit".

[0063] exist Figure 1 In the embodiment, the input voltage Vin from the DC power supply 1 is rectified by the rectifier circuit 3 after being switched by the inverter 2, and the rectified DC voltage is voltage-controlled by the post-regulator 4 so as to become a predetermined output voltage, and is supplied to the load resistor R L The output voltage Vout is outputted. The power transmitting inductor Lt of the inverter 2 and the power receiving inductor Lr of the rectifier circuit 3 are provided in close proximity to each other so as to be electromagnetically coupled at a coupling degree k.

[0064] exist Figure 1 In the embodiment, the inverter 2 is configured to include an input inductor Lc (choke coil), a switching MOS transistor Q1, a charging and discharging series capacitor Cs, a resonant capacitor C2, a resonant inductor L2, a power transmission capacitor Ct, a power transmission inductor Lt, and a control circuit 20. The input voltage Vin from the DC power supply 1 is input via the input inductor Lc and then is controlled by a gate control voltage (gate control signal) v from the control circuit 20. gs1 The control circuit 20 generates a PWM signal having a constant switching frequency fsw and a constant duty cycle (time ratio), that is, a gate control voltage v gs1The input voltage Vin is applied to the gate (control terminal) of the switching MOS transistor Q1, thereby switching the input voltage Vin. The input voltage Vin obtained by switching is charged by the series capacitor Cs, then discharged, and input to the series LC resonant circuit 21 (actually an RLC resonant circuit when the loss resistance is also taken into account) composed of capacitors C2, Ct and inductors L2, Lt, and only the component of the predetermined resonant frequency is extracted. The energy of the AC voltage is received by the power receiving inductor Lr of the rectifier circuit 3 via the power transmitting inductor Lt.

[0065] The inverter 2 constructed as described above constitutes a load-independent EF-type inverter, but the present invention is not limited thereto. Figure 4A to Figure 4G As described later, for example, the inverter may be composed of a load-independent class E inverter or the like.

[0066] The rectifier circuit 3 is configured to include a power receiving inductor Lr, a power receiving capacitor Cr, diodes D1 and D2 for half-bridge rectification, and a smoothing capacitor Cf. In the rectifier circuit 3, the AC voltage received by the power receiving inductor Lr is extracted only by a component of a predetermined resonant frequency by a series LC resonant circuit 31 composed of the power receiving inductor Lr and the power receiving capacitor Cr, and then rectified by diodes D1 and D2. Here, the resonant frequency of the series LC resonant circuit 31 of the rectifier circuit 3 and the resonant frequency of the series LC resonant circuit 21 of the inverter 2 are set to be substantially the same, for example. Then, after the rectified voltage is smoothed by the smoothing capacitor Cf, the smoothed voltage is input to the inductor Lr via the source and drain of the switching MOS transistor Q2 of the post regulator 4. post And diode D post .

[0067] The rectifier circuit 3 constructed as described above constitutes a current driven D-type rectifier circuit, but the present invention is not limited thereto. Figure 5A to Figure 5F As described later, for example, a rectifier circuit having a robust reactance component may be used.

[0068] The post regulator 4 is configured to include a switching MOS transistor Q2, a smoothing inductor L post (choke coil), half-wave rectifier diode D post , smoothing capacitor C post , Voltage detection voltage divider resistor R d1 , R d2 , Current detection resistor R C2 , a differential amplifier 41 for amplifying a current detection voltage, a control circuit 40 for current control, and a gate driver 42.

[0069] In the post regulator 4 configured as described above, the rectified voltage from the rectifier circuit 3 is controlled by the switching MOS transistor Q2 according to the PWM gate signal applied to the gate (control terminal) from the control circuit 40 via the gate driver 42, and then the rectified voltage is connected to the gate by the diode D post Half-wave rectification is performed. The rectified voltage is then smoothed by the inductor L post and smoothing capacitor C post After smoothing by the smoothing circuit, the load resistor R L Output output voltage Vout. Here, the output voltage Vout is divided by the voltage dividing resistor R d1 , R d2 The divided voltage is input to the control circuit 40 as a voltage for detecting the output voltage Vout. C2 Detection load resistor R L The flowing output current Iout is input to the control circuit 40 after being amplified by a detection voltage substantially proportional to the output current Iout by the differential amplifier 41 .

[0070] In the first embodiment, the post regulator 4 operates as a buck converter in an output voltage constant mode (CV mode: constant voltage mode), and the control circuit 40 controls the duty ratio of the PWM gate signal applied to the gate of the switching MOS transistor Q2 so that the output voltage Vout becomes a predetermined voltage based on the voltage detection voltage. In addition, the post regulator 4 may be configured as a boost converter or a buck / boost converter.

[0071] In the wireless power transmission system constructed as described above, by using a load-independent Class E inverter 2 and a rectifier circuit 3 that is independent of the reactance component, the resonant circuit 21 of the inverter 2 and the resonant circuit 31 of the rectifier circuit 3 are combined in an electromagnetically coupled manner. Even if the load changes within an arbitrary range, other circuit parameters (input voltage Vin, switching frequency fsw, duty cycle, etc.) will not change, and soft switching (ZVS) and constant output (constant output voltage Vout or constant output current Iout) can be achieved.

[0072] Furthermore, since a post-regulator 4 is provided at the rear stage of the rectifier circuit 3, constant voltage control is performed and the duty cycle of the post-regulator 4 is also controlled by changes in the coupling degree k, so that the impedance of the rear stage observed from the inverter 2 appears constant, thereby achieving soft switching (ZVS) and constant output (constant output voltage Vout or constant output current Iout).

[0073] Here, a supplementary explanation is given on why the output becomes constant when the impedance of the subsequent stage viewed from the inverter 2 appears to be constant. Figure 1 In the wireless power transmission system, the gain G when observing the subsequent stage from the input terminal of the inverter 2 is expressed by the following formula.

[0074] G=Voeq / Vin (1)

[0075] Here, Voeq is the equivalent load resistance R applied when the inverter 2 is viewed from the downstream. eq Here, the equivalent load resistance R is expressed by the following formula: eq .

[0076] R eq =(π 2 k 2 ω 2 LqCy post 2 ) / 2R L (2)

[0077] Here, ω is the frequency of the AC voltage, D post is the duty cycle of the post regulator 4.

[0078] As is clear from the equation (2), for example, when the coupling degree k is relatively large, the duty ratio (on time ratio) D of the post regulator 4 is reduced. post , and when the coupling degree k is relatively small, the duty cycle (on time ratio) D of the post regulator 4 is increased. post The equivalent load resistance R Leq By controlling the equivalent load resistance R Leq The voltage Voeq (formula (1)) is controlled to be constant. In addition, in the first embodiment, when the coupling degree k changes, the duty ratio of the post regulator 4 is calculated so as to become the desired output voltage Vout (constant impedance), so that the control circuit 40 can control the output voltage Vout to a predetermined voltage.

[0079] As described above, according to the first embodiment, it is possible to provide a wireless power transmission system capable of making the output voltage Vout constant with respect to changes in the coupling degree k.

[0080] (Implementation Method 2)

[0081] Figure 2 is a circuit diagram showing a configuration example of a wireless power transmission system according to Embodiment 2. Figure 2 In, with Figure 1 Compared with the wireless power transmission system of the first embodiment, the wireless power transmission system of the second embodiment is different in the following aspects.

[0082] (1) The pre-regulator 6 is provided between the DC power supply 1 and the inverter 2 . The pre-regulator 6 includes a communication circuit 63 having an antenna 63A and a control circuit 60 .

[0083] (2) The post regulator 4A is provided instead of the post regulator 4 , and the post regulator 4A further includes the communication circuit 43 , and the communication circuit 43 performs wireless communication with the communication circuit 63 .

[0084] (3) The post regulator 4A further includes an operation unit 45 connected to the control circuit 40 and used by a user to operate switching of the operation mode.

[0085] (4) The pre-regulator 6 further includes an operation unit 65 connected to the control circuit 60 and used by a user to operate switching of the operation mode.

[0086] The differences are described below.

[0087] exist Figure 2 In the embodiment, the pre-regulator 6 and the inverter 2 constitute a “wireless power transmission circuit”, and the rectifier circuit 3 and the post-regulator 4A constitute a “wireless power reception circuit”.

[0088] The pre-regulator 6 is configured to include a switching MOS transistor Q3, a smoothing inductor L pre (choke coil), half-wave rectifier diode D pre , smoothing capacitor C pre , Current detection resistor R C1 , a differential amplifier 61 for amplifying a current detection voltage, a control circuit 60 for current control, and a gate driver 62.

[0089] In the pre-regulator 6 configured as described above, the DC voltage Vin from the DC power supply 1 is controlled by the switching MOS transistor Q3 according to the PWM gate signal applied to the gate (control terminal) from the control circuit 60 via the gate driver 62, and then the DC voltage Vin is connected to the gate by the diode D pre Half-wave rectification is performed. The rectified voltage is then smoothed by the inductor L pre and smoothing capacitor C pre After smoothing by the smoothing circuit, the output voltage is passed through the current detection resistor R C1 The current is output to the input inductor Lc of the inverter 2. C1 Detection direction current detection resistor R C1 The flowing input current Iin is input to the control circuit 60 after being amplified by a differential amplifier 61 as a detection voltage substantially proportional to the input current Iin.

[0090] The pre-regulator 6 configured as described above operates in an output current constant mode (CC mode: constant current mode) or a predetermined constant duty ratio mode. In the CC mode, the control circuit 60 operates in a proportional component control mode, and controls the duty ratio of the PWM gate signal applied to the gate of the switching MOS transistor Q3 so that the input current Iin becomes a predetermined current. On the other hand, in the constant duty ratio mode, the control circuit 60 sets the duty ratio of the PWM gate signal applied to the gate of the switching MOS transistor Q3 to a predetermined value, that is, a constant value.

[0091] As described in the first embodiment, the post regulator 4A can operate in either the output voltage constant mode (CV mode) or the output current constant mode (CC mode), and when the user switches the operation mode using the operation unit 45, the post regulator 4A is further provided with a communication circuit 43 in order to wirelessly transmit an operation mode switching signal to the control circuit 60 of the pre-regulator 6, and the communication circuit 43 has an antenna 43A. The control circuit 60 of the pre-regulator 6 is set to operate the pre-regulator 6 in the constant duty cycle mode in response to the operation mode switching signal of the CV mode from the control circuit 40. On the other hand, the control circuit 60 of the pre-regulator 6 is set to operate the pre-regulator 6 in the CC mode in response to the operation mode switching signal of the CC mode from the control circuit 40.

[0092] In addition, for example, in the post-regulator 4A, the user uses the operation unit 45 connected to the control circuit 40 to switch, thereby generating an operation mode switching signal indicating each operation mode, and the operation mode switching signal is not a signal that is always transmitted and received, but is transmitted and received only when the operation mode is switched. In addition, in the pre-regulator 6, the user uses the operation unit 65 connected to the control circuit 60 to switch, thereby generating an operation mode switching signal. In this case, the operation mode switching signal is sent from the control circuit 60 to the control circuit 40 via the communication circuits 63 and 43.

[0093] In Embodiment 2,

[0094] (A) When the wireless power transmission system is in CC mode,

[0095] The pre-regulator 6 operates in the CC mode, and the post-regulator 4A operates in the CC mode.

[0096] (B) When the wireless power transmission system is in CV mode,

[0097] The pre-regulator 6 operates in a constant duty mode (constant time ratio mode), and the post-regulator 4A operates in a CV mode.

[0098] Next, refer to Figure 3The operation of the CV mode of the first embodiment and the operation of the CC mode of the second embodiment are described below. Figure 3 This is an equivalent circuit diagram for explaining the case where the output voltage can be made constant in the first embodiment.

[0099] In the CV mode of implementation mode 1,

[0100] (1) When observing the downstream stage from the DC power supply 1, the output voltage is controlled in CV mode with constant output voltage.

[0101] (2) When looking at the rear stage from the inverter 2, the output current is controlled in CC mode with constant output current.

[0102] (3) When observing the subsequent stage from the rectifier circuit 3, the output voltage is controlled in a CV mode with a constant output voltage.

[0103] (4) When the post-regulator 4 is viewed from the downstream side, the post-regulator 4 is controlled in a CV mode in which the output voltage is constant.

[0104] exist Figure 3 In FIG. 7 , when an equivalent circuit 7 when the subsequent circuit is viewed from the power transmission inductor Lt of the inverter 2 is represented by a series circuit of an equivalent inductor Leq and an equivalent resistor Req, the equivalent resistor Req is represented by the following equation similarly to equation (2).

[0105] R eq

[0106] =(k 2 ω 2 LtLr) / (R L +r Lr )+r Lt

[0107] ≒(π 2 k 2 ω 2 LqCy post 2 ) / R L (3)

[0108] Here, r Lr is the loss resistance of the receiving inductor Lr, r Lt is the loss resistance of the power transmission inductor Lt. As is clear from the equation (3), the entire wireless power transmission system of the first embodiment is controlled in the CV mode.

[0109] Next, in the CC mode of implementation mode 2,

[0110] (1) When observing the downstream stage from the DC power supply 1, the output voltage is controlled in CV mode with constant output voltage.

[0111] (2) When observing the subsequent stage from the pre-regulator 6, the output current is controlled in CC mode with constant output current.

[0112] (3) When looking at the downstream stage from the inverter 2, the output voltage is controlled in a CV mode with a constant output voltage.

[0113] (4) When observing the subsequent stage from the rectifier circuit 3, the output current is controlled in CC mode,

[0114] (5) When the post-regulator 4A is viewed from the downstream side, the post-regulator 4A is controlled in the CC mode in which the output current is constant.

[0115] That is, in the entire wireless power transmission system according to the second embodiment, control is performed in the CC mode in this case.

[0116] As described above, according to the second embodiment, compared with the first embodiment, the load resistor R L The output of the pre-regulator 6 is a CV (constant voltage) characteristic. By adding the pre-regulator 6 and performing duty control, the post-regulator 4A can output a constant current according to the CC mode. At this time, the duty control of the post-regulator 4A is the same as that of the post-regulator 4 involved in the first embodiment. pre The current Iin flowing through the (choke coil) is detected, and duty control is performed so that the current value becomes constant, so the control of the pre-regulator 6 is closed on the power transmission side.

[0117] The reason for adding communication between the power transmission and the power reception is that in addition to the CV mode, the CC mode can be performed in the entire wireless power transmission system, so it is necessary to synchronize the communication between the power transmission and the power reception at the timing of switching between the CV mode and the CC mode. In the CV mode of the wireless power transmission system, the duty control of the pre-regulator 6 is stopped and set to a constant duty ratio, and the post-regulator 4A is operated in the CV mode as a circuit similar to the first embodiment, and the duty ratio is controlled. In addition, in the CC mode of the wireless power transmission system, the pre-regulator 6 and the post-regulator 4A are operated in the CC mode.

[0118] According to the structure of the second embodiment, in addition to the effect of the first embodiment that soft switching and changes in coupling degree k are handled by load independence, charging in CC mode or CV mode can be performed (when the load is a secondary battery). Since communication between the power transmission and reception is only required when switching between CC mode and CV mode, there is no risk of excessive output voltage or current due to interruption of communication.

[0119] (Variation Example)

[0120] Next, replace Figure 1 as well as Figure 2 A modification example of an inverter that can be used instead of the inverter 2 is described.

[0121] (Modification 1 of Inverter 2)

[0122] Figure 4A It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2A according to a first modification of the inverter 2 is shown. Figure 4A In FIG. 2 , the inverter 2A is configured to include an input inductor Li, a switching MOS transistor Q1 , a series capacitor Cs, a power transmission capacitor Ct, and a power transmission inductor Lt.

[0123] In the inverter 2A configured as described above, the input voltage Vin from the DC power supply 1 is input to the switching MOS transistor Q1 via the input inductor Li, and then switched by the switching MOS transistor Q1. The voltage obtained by switching is filtered only for a predetermined resonant frequency component by an LC resonant circuit composed of capacitors Cs, Ct and a power transmission inductor Lt, and then the filtered AC voltage is transmitted from the power transmission inductor Lt. Here, the inverter 2A constitutes a load-independent E-class inverter, which can operate in a ZVS mode and in a CV mode.

[0124] (Modification 2 of Inverter 2)

[0125] Figure 4B It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2B according to a second modification of the inverter 2 is shown. Figure 4B In FIG. 2 , the inverter 2B is configured to include an input inductor Li, a switching MOS transistor Q1 , a series capacitor Cs, a capacitor C2 , an inductor L2 , a power transmission capacitor Ct, and a power transmission inductor Lt.

[0126] In the inverter 2B configured as described above, the input voltage Vin is input to the switching MOS transistor Q1 via the input inductor Li, and then switched by the switching MOS transistor Q1. The voltage obtained by switching is filtered only for a predetermined resonant frequency component by an LC resonant circuit composed of capacitors Cs, C2, Ct, inductor L2, and a power transmission inductor Lt, and then the filtered AC voltage is transmitted from the power transmission inductor Lt via the power transmission capacitor Ct. Here, the inverter 2B configures a load-independent E-class inverter, and can operate in a ZVS mode and in a CC mode.

[0127] (Variation 3 of Inverter 2)

[0128] Figure 4C It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2C according to a third modification of the inverter 2 is shown in FIG. Figure 4C In FIG. 2 , the inverter 2C is configured to include an inductor Ls, a switching MOS transistor Q1 , a series capacitor Cs, an inductor Lc, a power transmission capacitor Ct, and a power transmission inductor Lt.

[0129] In the inverter 2C configured as described above, the input voltage Vin from the DC power supply 1 is input to the switching MOS transistor Q1 via the inductors Lc and Ls, and then switched by the switching MOS transistor Q1. The voltage obtained by switching is filtered only for a predetermined resonant frequency component by an LC resonant circuit composed of capacitors Cs and Ct and a power transmission inductor Lt, and then the filtered AC voltage is transmitted from the power transmission inductor Lt. Here, the inverter 2C constitutes a load-independent E-type inverter, which can operate in a ZCS mode and in a CC mode.

[0130] (Variation 4 of Inverter 2)

[0131] Figure 4D It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2D according to a fourth modification of the inverter 2 is shown. Figure 4D In the embodiment, the inverter 2D is composed of inductors L1, Lc, a switching MOS transistor Q1, a capacitor C1, a power transmission capacitor Ct, a voltage dividing resistor R d1 , R d2 , a feedback circuit consisting of a capacitor Cf and an inductor Lf, a power transmission capacitor Ct, and a power transmission inductor Lt.

[0132] In the inverter 2D configured as described above, the input voltage Vin from the DC power supply 1 is divided by the voltage dividing resistor R d1 , R d2 The divided voltage obtained by voltage division becomes the gate voltage of the switching MOS transistor Q1, and is fed back to the power transmission inductor Lt via the inductor Lf of the feedback circuit. In addition, the input voltage Vin is switched by the switching MOS transistor Q1 after being input to the switching MOS transistor Q1 via the inductors Lc and L1. The voltage obtained by switching is transmitted from the power transmission inductor Lt after filtering only the predetermined resonant frequency component through the resonant circuit composed of the capacitor Ct and the inductor Lt via the capacitor C1. Here, the inverter 2D constitutes a load-independent reverse E-class decoupling oscillation inverter, which can operate in ZCS mode and in CV mode.

[0133] (Variation Example 5 of Inverter 2)

[0134] Figure 4E It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2E according to a fifth modification of the inverter 2 is shown. Figure 4E In FIG. 2 , the inverter 2E is configured to include inductors L1 and Lc, a switching MOS transistor Q1 , a capacitor C1 , a power transmission capacitor Ct, and a power transmission inductor Lt.

[0135] In the inverter 2E configured as described above, the input voltage Vin from the DC power supply 1 is input to the switching MOS transistor Q1 via the inductors Lc and L1, and then switched by the switching MOS transistor Q1. The voltage obtained by switching is filtered only by a predetermined resonant frequency component through the resonant circuit composed of the transmission capacitor Ct and the transmission inductor Lt via the inductor L1 and the capacitor C1, and then transmitted from the transmission inductor Lt. Here, the inverter 2E constitutes a load-independent E-type inverter, which can operate in the ZCS mode and in the CV mode.

[0136] (Variation Example 6 of Inverter 2)

[0137] Figure 4F It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2F according to a sixth modification of the inverter 2 is shown. Figure 4F In FIG. 2 , the inverter 2F is configured to include inductors Lc and Ls, a capacitor Cs, a switching MOS transistor Q1 , a capacitor C1 , a power transmission capacitor Ct, and a power transmission inductor Lt.

[0138] In the inverter 2F configured as described above, the input voltage Vin from the DC power supply 1 is input to the switching MOS transistor Q1 via the inductors Lc and Ls, and then switched by the switching MOS transistor Q1. The voltage obtained by switching is filtered only for a predetermined resonant frequency component through the resonance circuit composed of the transmission capacitor Ct and the transmission inductor Lt via the capacitor Cs, the inductor Ls, and the capacitor C1, and then transmitted from the transmission inductor Lt. Here, the inverter 2F configures a load-independent E-class inverter, and can operate in the ZVS mode and in the CC mode.

[0139] (Variation Example 7 of Inverter 2)

[0140] Figure 4G It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of an inverter 2G according to a modification example 7 of the inverter 2 is shown. Figure 4G Inverter 2G is Figure 4BThe inverter 2B of the embodiment is transformed into a push-pull inverter, and compared with the structure of the inverter 2B, it further includes a switching MOS transistor Q1a, a series capacitor Csa, inductors Lia, L2a, and a capacitor C2a. In addition, the switching MOS transistor Q1a is controlled by a gate control voltage v from the control circuit 20. gs1a Make a switch.

[0141] In the inverter 2G configured as described above, the input voltage Vin from the DC power supply 1 is input to the switching MOS transistors Q1 and Q1a via the input inductors Li and Lia, respectively, and then switched by the switching MOS transistors Q1 and Q1a. Each voltage obtained by switching is filtered only for a predetermined resonant frequency component through an LC resonant circuit composed of capacitors Cs, C2, Ct, inductor L2, and a power transmission inductor Lt, and an LC resonant circuit composed of capacitors Csa, C2a, inductor L2a, and a power transmission inductor Lt, and then the filtered AC voltage is transmitted from the power transmission inductor Lt via the capacitor Ct. Here, the inverter 2G is a push-pull load-independent EF-type inverter, which can operate in a ZVS mode and in a CC mode.

[0142] Next, replace Figure 1 as well as Figure 2 A modification example of the rectifier circuit that can be used with the rectifier circuit 3 is described.

[0143] (Variation 1 of Rectifier Circuit 3)

[0144] Figure 5A It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3A according to a first modification of the rectifier circuit 3 is shown. Figure 5A In FIG. 1 , the rectifier circuit 3A is configured to include a power receiving inductor Lr, a power receiving capacitor Cr, diodes D1 and D2, and a smoothing capacitor Cf.

[0145] In the rectifier circuit 3A configured as above, the AC voltage is received by the power receiving inductor Lr, half-wave rectified by the diodes D1 and D2 via the power receiving capacitor Cr, smoothed by the smoothing capacitor Cf, and then supplied to the load resistor R. L Here, the rectifier circuit 3A constitutes a half-bridge current-driven class-D rectifier circuit.

[0146] (Variation 2 of Rectifier Circuit 3)

[0147] Figure 5B It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3B according to a second modification of the rectifier circuit 3 is shown. Figure 5B In FIG. 1 , the rectifier circuit 3B is configured to include a power receiving inductor Lr, a power receiving capacitor Cr, diodes D1 to D4 , and a smoothing capacitor Cf.

[0148] In the rectifier circuit 3B configured as described above, the AC voltage is received by the power receiving inductor Lr, full-wave rectified by the diodes D1 to D4 via the power receiving capacitor Cr, smoothed by the smoothing capacitor Cf, and then supplied to the load resistor R. L Here, the rectifier circuit 3B constitutes a full-bridge current-driven class-D rectifier circuit.

[0149] (Variation 3 of Rectifier Circuit 3)

[0150] Figure 5C It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3C according to a modification example 3 of the rectifier circuit 3 is shown. Figure 5C In FIG. 1 , the rectifier circuit 3C is configured to include a power receiving inductor Lr, a smoothing capacitor Cfa, diodes D1 and D2, a smoothing inductor Lf, and a smoothing capacitor Cf.

[0151] In the rectifier circuit 3C configured as above, the AC voltage is received by the power receiving inductor Lr and then smoothed by the smoothing capacitor Cfa. The smoothed voltage is full-wave rectified by the diodes D1 and D2, and then smoothed by the smoothing inductor Lf and the smoothing capacitor Cf and transmitted to the load resistor R. L Here, the rectifier circuit 3C constitutes a half-bridge voltage-driven class-D rectifier circuit.

[0152] (Variation 4 of Rectifier Circuit 3)

[0153] Figure 5D It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3D according to a modification example 4 of the rectifier circuit 3 is shown. Figure 5D In FIG. 1 , the rectifier circuit 3D is configured to include a power receiving inductor Lr, a smoothing capacitor Cr, diodes D1 to D4 , a smoothing inductor Lf, and a smoothing capacitor Cf.

[0154] In the rectifier circuit 3D configured as above, the AC voltage is received by the power receiving inductor Lr and then smoothed by the smoothing capacitor Cr. The smoothed voltage is full-wave rectified by the diodes D1 to D4, and then smoothed by the smoothing inductor Lf and the smoothing capacitor Cf and transmitted to the load resistor R. L Here, the rectifier circuit 3D constitutes a full-bridge voltage-driven class-D rectifier circuit.

[0155] (Variation 5 of Rectifier Circuit 3)

[0156] Figure 5E It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3E according to a fifth modification of the rectifier circuit 3 is shown. Figure 5E In FIG. 1 , the rectifying circuit 3E is configured to include a power receiving inductor Lr, a smoothing capacitor Cs, a series capacitor Cr, a switching MOS transistor Q4, a smoothing inductor Lc, and a smoothing capacitor Cf.

[0157] In the rectifier circuit 3E configured as above, the AC voltage is received by the power receiving inductor Lr and then filtered by a resonant circuit having a predetermined resonant frequency formed by the inductor Lr and capacitors Cr and Cs. The filtered AC voltage is then adjusted according to a predetermined gate control voltage v gs4 After being switched by the switching MOS transistor Q4, the current is smoothed by the smoothing inductor Lc and the smoothing capacitor Cf and then sent to the load resistor R L Here, the rectifier circuit 3E constitutes a load-independent E-class rectifier circuit.

[0158] (Variation 6 of Rectifier Circuit 3)

[0159] Fig. 5F It is shown Figure 1 as well as Figure 2 A circuit diagram of a configuration example of a rectifier circuit 3F according to a modification example 6 of the rectifier circuit 3 is shown. Fig. 5F In FIG. 1 , the rectifier circuit 3F is configured to include a power receiving inductor Lr, a power receiving capacitor Cr, an inductor L2, a capacitor C2, a smoothing capacitor Cs, a switching MOS transistor Q4, a smoothing inductor Lc, and a smoothing capacitor Cf.

[0160] In the rectifier circuit 3F configured as above, after the AC voltage is received by the power receiving inductor Lr, it is filtered by a resonant circuit having a predetermined resonant frequency composed of the inductor Lr, the power receiving capacitor Cr, the inductor L2 and the capacitor C2. The filtered AC voltage is then adjusted according to the predetermined gate control voltage v gs4 After being switched by the switching MOS transistor Q4, the current is smoothed by the smoothing inductor Lc and the smoothing capacitor Cf and then sent to the load resistor R L Here, the rectifier circuit 3F constitutes a load-independent EF-type rectifier circuit.

[0161] (Other Modifications)

[0162] In the above embodiments and modifications, the post regulators 4 and 4A and the pre-regulator 6 may be, for example, a step-up DC-DC converter, a step-down DC-DC converter, or a step-up / step-down DC-DC converter.

[0163] In the above embodiment and modification examples, MOS transistors Q1 to Q4 and Q1 a are used, but the present invention is not limited thereto, and other types of transistors such as bipolar transistors may be used, for example.

[0164] In the above embodiment, the communication circuits 43 and 63 are wireless communication circuits using wireless communication, but the present invention is not limited to this, and for example, they may be wired communication circuits using wired communication.

[0165] Industrial Applicability

[0166] As described above in detail, according to the present invention, a wireless power transmission system, a wireless power transmission circuit and a wireless power receiving circuit for the wireless power transmission system can be provided, which can make the output voltage or output current constant with respect to the change of the coupling degree k. The wireless power transmission system can be applied to power supply to mobile bodies such as AGV and EV, and can also be applied to power supply to slip rings (rotating bodies) used in pallets or robot arms of production lines.

[0167] Description of Reference Numerals

[0168] 1: DC power supply; 2: inverter; 3: rectifier circuit; 4, 4A: post-regulator; 5: load; 6: pre-regulator; 7: post-stage equivalent circuit; 20: control circuit; 21: resonant circuit; 31: resonant circuit; 40: control circuit; 41: differential amplifier; 42: gate driver; 43: communication circuit; 43A: antenna; 45: operation unit; 60: control circuit; 61: differential amplifier; 62: gate driver; 63: communication circuit; 63A: antenna; 65: operation unit; C1, C2, Cf, Cfa, C post , C pre , Cr, Cs, Ct, C51~C63, Cres, C DC : Capacitor; D1, D2, D pre , D post : diode; L1, L2, Lc, Leq, Li, L post , L pre , Lr, Ls, Lt, L51~L63: inductors; Q1~Q4, Q51, Q61: MOS transistors; R C1 , R C2 , R d1 , R d2 , R eq 、r L2 : resistance; R L : Load resistance.

Claims

1. A wireless power transmission system, comprising a wireless power transmission circuit and a wireless power receiving circuit, wherein: The wireless power transmission circuit includes an inverter. The inverter includes a first LC resonant circuit, the first LC resonant circuit includes a power transmission inductor, the inverter switches an input voltage at a predetermined switching frequency and a predetermined duty cycle, and transmits an AC voltage obtained by switching from the power transmission inductor, The wireless power receiving circuit comprises: a rectifier circuit including a second LC resonant circuit including a power receiving inductor electromagnetically coupled to the power transmitting inductor, the rectifier circuit rectifying an AC voltage received by the power receiving inductor and outputting a rectified voltage; and The first regulator detects an output voltage from the first regulator, controls the rectified voltage based on the detected output voltage so that the output voltage becomes a predetermined voltage, and outputs the output voltage.

2. The wireless power transmission system according to claim 1, wherein: The first regulator includes a first current control transistor, which controls the current related to the AC voltage from the rectifier circuit. The first regulator controls the rectified voltage based on the detected output voltage in such a way that the output voltage becomes a predetermined voltage by controlling the duty cycle of the control signal relative to the control terminal of the first current control transistor.

3. The wireless power transmission system according to claim 1, wherein: The inverter includes an E-class inverter, an inverse E-class inverter, an EF-class inverter or an inverse E-class decoupling oscillation inverter, The rectifier circuit includes a class D rectifier circuit, a class E rectifier circuit or a class EF rectifier circuit, The first regulator includes a DC-DC converter.

4. The wireless power transmission system according to any one of claims 1 to 3, wherein: The wireless power transmission circuit further includes a second regulator, which is disposed in the front section of the inverter. The second regulator includes a second current control transistor, The second regulator has the following operation modes: (A) a constant current mode, detecting an output current from the second regulator, controlling the second current control transistor based on the detected output current, thereby controlling the input voltage in such a way that the output current becomes a predetermined current, and outputting the output current to the inverter; as well as (B) a constant time ratio mode, controlling the input voltage by controlling the second current control transistor at a constant duty ratio, and outputting the output voltage to the inverter, The first regulator has an operation mode of a constant current mode in addition to the following (A) constant voltage mode. The (A) constant voltage mode detects the output voltage from the first regulator, controls the rectified voltage so that the output voltage becomes a predetermined voltage based on the detected output voltage, and outputs the output voltage. The (B) constant current mode detects an output current from the first regulator, controls the rectified voltage based on the detected output current so that the output current becomes a predetermined current, and outputs the output voltage, The first regulator further includes a first communication circuit. When selectively switching between the constant voltage mode and the constant current mode, the first communication circuit sends an operation mode switching signal to the second regulator, or receives an operation mode switching signal from the second regulator. The second regulator further includes a second communication circuit. When selectively switching between the constant time ratio mode and the constant current mode, the second communication circuit sends an operation mode switching signal to the first regulator, or receives an operation mode switching signal from the first regulator. The wireless power transmission system is configured such that when the first regulator operates in the constant voltage mode, the second regulator operates in the constant time ratio mode. And when the first regulator operates in the constant current mode, the second regulator operates in the constant current mode.

5. The wireless power transmission system according to claim 4, wherein: The second regulator includes a DC-DC converter.

6. A wireless power transmission circuit, used in the wireless power transmission system according to any one of claims 1 to 3, wherein: The wireless power transmission circuit includes the inverter.

7. A wireless power receiving circuit, used in the wireless power transmission system according to any one of claims 1 to 3, wherein: The wireless power receiving circuit includes the rectifier circuit and the first regulator.

8. A wireless power transmission circuit, used in the wireless power transmission system according to claim 4, wherein: The wireless power transmission circuit includes the second regulator and the inverter.

9. A wireless power receiving circuit, used in the wireless power transmission system according to claim 4, wherein: The wireless power receiving circuit includes the rectifier circuit and the first regulator.

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