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

Abstract

To provide a wireless power transfer system and the like capable of keeping output voltage and the like constant despite fluctuation of a coupling degree of a pair of coils electromagnetically coupled to each other.SOLUTION: A wireless power transfer system comprises: a wireless power transmission circuit comprising an inverter that includes a first LC resonance circuit including a power transmission inductor, and switches an input voltage at a predetermined switching frequency and a predetermined duty ratio to transmit power with a switched AC voltage from the power transmission inductor; and a wireless power reception circuit. The wireless power reception circuit is a rectification circuit including a second LC resonance circuit including a power reception inductor electromagnetically coupled to the power transmission inductor, and comprises: the rectification circuit that rectifies an AC voltage received by the power reception inductor to output a rectified voltage; and a first regulator that detects an output voltage from the first regulator, and controls the rectified voltage so that an output voltage becomes a predetermined voltage on the basis of the detected output voltage to output the output voltage.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wireless power transmission system including a wireless power transmission circuit and a wireless power reception circuit that are electromagnetically coupled, a wireless power transmission circuit for the wireless power transmission system, and a wireless power reception circuit for the wireless power transmission system.

Background Art

[0002] Conventionally, mobile bodies such as wireless transfer vehicles (AGVs (Automatic Guided Vehicles)) and electric vehicles (EVs (Electric Vehicles)) carry rechargeable batteries such as lithium-ion batteries. When charging this rechargeable battery, after moving the AGV to a charging station, a power reception coil mounted on the AGV is electromagnetically coupled to a power transmission coil of the charging station to perform contactless charging in a contactless charging system.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, contactless charging is performed by electromagnetically coupling the receiving coil to the transmitting coil, but the following factors can cause changes. (Change Element A) When the remaining charge of the rechargeable battery or the operation of the device acting as the load changes, the load changes. (Variable element B) The degree of coupling k between the transmitting and receiving coils changes due to the misalignment of the coils.

[0006] In other words, it became difficult to change the output characteristics related to voltage or current, which presented a challenge in achieving soft switching such as zero-volt switching (ZVS) or zero-current switching (ZCS).

[0007] To solve this problem, Figure 32 of Non-Patent Document 1 (Figure 6 of this application) shows that, as described later in "Inventor's Knowledge," by combining a Class E inverter and a rectifier circuit, "Variable Element A" can achieve soft switching while keeping the output voltage constant, while "Variable Element B" can achieve soft switching but cannot keep the output voltage constant. In other words, the problem remains that the output characteristics related to voltage or current change with respect to fluctuations in the coupling degree k.

[0008] The object of the present invention is to solve the problems of conventional systems and to provide a wireless power transmission system, a wireless power transmission circuit, and a wireless power receiving circuit that can keep the output voltage or output current constant with respect to fluctuations in the coupling degree k. [Means for solving the problem]

[0009] A wireless power transmission system according to a first aspect of the present invention is: A wireless power transmission system comprising a wireless power transmission circuit and a wireless power receiving circuit, The aforementioned wireless power transmission circuit is An inverter comprising a first LC resonant circuit including a power transmission inductor, wherein the inverter switches an input voltage at a predetermined switching frequency and a predetermined duty cycle, and transmits the switched AC voltage from the power transmission inductor, The aforementioned wireless power receiving circuit is A rectifier circuit including a second LC resonant circuit which includes a receiving inductor electromagnetically coupled to the transmitting inductor, the rectifier circuit which rectifies the AC voltage received by the receiving inductor and outputs a rectified voltage, The system includes a first regulator that detects the 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.

[0010] A wireless power transmission system according to a second aspect of the present invention is a wireless power transmission system according to the first aspect, The wireless power transmission circuit further includes a second regulator provided in front of the inverter, The second regulator includes a second current control transistor. The second regulator is, (A) A constant current mode in which the output current from the second regulator is detected, and the second current control transistor is controlled based on the detected output current to control the input voltage so that the output current becomes a predetermined current, and the output current is output to the inverter, (B) A constant ratio mode in which the input voltage is controlled by controlling the second current control transistor with a constant duty cycle, and the output voltage is output to the inverter, It has an operating mode, The first regulator described above is (A) In addition to a constant voltage mode in which the output voltage from the first regulator is detected and the rectified voltage is controlled based on the detected output voltage so that the output voltage becomes a predetermined voltage, (B) The system has a constant current mode operation mode that detects the 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, The system includes a first communication circuit that transmits an operating mode switching signal to the second regulator or receives an operating mode switching signal from the second regulator when selectively switching between the constant voltage mode and the constant current mode. The second regulator further, The system includes a second communication circuit that transmits an operating mode switching signal to the first regulator or receives an operating mode switching signal from the first regulator when selectively switching between the constant ratio mode and the constant current mode. When the first regulator operates in the constant voltage mode, the second regulator operates in the constant ratio mode. When the first regulator operates in the constant current mode, the second regulator is configured to operate in the constant current mode. [Effects of the Invention]

[0011] Therefore, according to the wireless power transmission system of the present invention, the output voltage or output current can be kept constant with respect to fluctuations in the degree of coupling k. [Brief explanation of the drawing]

[0012] [Figure 1] This is a circuit diagram showing an example configuration of a wireless power transmission system according to Embodiment 1. [Figure 2] This is a circuit diagram showing an example configuration of a wireless power transmission system according to Embodiment 2. [Figure 3] This is an equivalent circuit diagram illustrating how the output voltage can be kept constant in Embodiment 1. [Figure 4A] This is a circuit diagram showing an example configuration of inverter 2A related to Modification 1 of inverter 2 shown in Figures 1 and 2. [Figure 4B] This is a circuit diagram showing an example configuration of inverter 2B, which is a modified example 2 of inverter 2 shown in Figures 1 and 2. [Figure 4C] This is a circuit diagram showing an example configuration of inverter 2C related to Modification 3 of inverter 2 shown in Figures 1 and 2. [Figure 4D]This is a circuit diagram showing an example configuration of inverter 2D, which is a modified example 4 of inverter 2 as shown in Figures 1 and 2. [Figure 4E] This is a circuit diagram showing an example configuration of inverter 2E related to Modification 5 of inverter 2 shown in Figures 1 and 2. [Figure 4F] This is a circuit diagram showing an example configuration of inverter 2F, which relates to modified example 6 of inverter 2 shown in Figures 1 and 2. [Figure 4G] This is a circuit diagram showing an example configuration of inverter 2G related to modified example 7 of inverter 2 shown in Figures 1 and 2. [Figure 5A] This is a circuit diagram showing an example configuration of rectifier circuit 3A related to modification 1 of the rectifier circuit 3 shown in Figures 1 and 2. [Figure 5B] This is a circuit diagram showing an example configuration of rectifier circuit 3B, which is a modified example 2 of the rectifier circuit 3 shown in Figures 1 and 2. [Figure 5C] This is a circuit diagram showing an example configuration of a rectifier circuit 3C related to a modified example 3 of the rectifier circuit 3 shown in Figures 1 and 2. [Figure 5D] This is a circuit diagram showing an example configuration of a rectifier circuit 3D related to a modified example 4 of the rectifier circuit 3 shown in Figures 1 and 2. [Figure 5E] This is a circuit diagram showing an example configuration of a rectifier circuit 3E related to a modified example 5 of the rectifier circuit 3 shown in Figures 1 and 2. [Figure 5F] This is a circuit diagram showing an example configuration of rectifier circuit 3F, which is a modified example 6 of the rectifier circuit 3 shown in Figures 1 and 2. [Figure 6] This is a circuit diagram showing the 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. [Figure 7] This is a circuit diagram showing the 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. [Modes for carrying out the invention]

[0013] Embodiments and modified examples of the present invention will be described below with reference to the drawings. The same or similar components are denoted by the same reference numerals.

[0014] (Inventor's insights) Figure 6 is a circuit diagram showing the configuration of a load-independent synchronous Class E rectifier circuit for a wireless power transmission system according to Conventional Example 1 disclosed in Figure 32 of Non-Patent Document 1. In Figure 6, the load-independent synchronous Class E rectifier circuit consists 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 inductor L51 and capacitors C51,C DC It is configured with a π-type smoothing circuit consisting of the following. Here, "load-independent" means a state in which the output characteristics of the circuit (voltage, current, or power) remain constant even if the resistance or impedance value of the load connected to the output of the circuit, such as a secondary battery, fluctuates. This load independence makes it possible to achieve soft switching regardless of the load.

[0015] In the rectifier circuit shown in Figure 6, configured as described above, the induced AC voltage is applied to the series inductor Ls, and the gate control voltage v gs5 According to the signal, the signal is switched and rectified by the switching MOS transistor Q51, and then the load resistor R L The rectified DC voltage Vout is output.

[0016] Figure 7 is a circuit diagram showing the configuration of a load-independent synchronous EF class inverter for a wireless power transmission system according to Conventional Example 2 disclosed in Figure 17 of Non-Patent Document 1. The EF class inverter in Figure 7 is configured to include a switching MOS transistor Q61, an input inductor L61, capacitors C61, C62, C63, Cs, and inductors L62, L63, Ls. Here, capacitors C62, C63 and inductors L62, L63 constitute a first LC resonant circuit having a predetermined resonant frequency, and inductor Ls and capacitor Cs constitute a second LC resonant circuit having a predetermined resonant frequency.

[0017] In the inverter shown in Figure 7, configured as described above, the AC voltage is applied to the switching MOS transistor Q61 via the input inductor L61, and the gate control voltage vgs6 The switching MOS transistor Q61 switches accordingly, and after the resonant circuit filters out only the predetermined resonant frequency components, the filtered AC voltage is then applied to the load resistor R L It will be output to [this location].

[0018] As is clear from Figures 6 and 7, by combining a Class E inverter and a rectifier circuit, it is possible to achieve soft switching by keeping the output voltage constant in response to changes in the load (changing element A), and to achieve soft switching in response to the coupling degree k (changing element B), but there was a problem in that the output voltage could not be kept constant. In other words, the problem remains that the output characteristics related to voltage or current change in response to fluctuations in the coupling degree k. In an embodiment of the present invention, a wireless power transmission system is proposed that can keep the output voltage or output current constant in response to fluctuations in the coupling degree k.

[0019] (Embodiment 1) Figure 1 is a circuit diagram showing an example configuration of a wireless power transmission system according to Embodiment 1. In Figure 1, the wireless power transmission system comprises an inverter 2, a rectifier circuit 3, and a post-regulator 4. Here, the inverter 2 constitutes a "wireless power transmission circuit," and the rectifier circuit 3 and post-regulator 4 constitute a "wireless power receiving circuit."

[0020] In Figure 1, the input voltage Vin from the DC power supply 1 is switched by the inverter 2, then rectified by the rectifier circuit 3, and the rectified DC voltage is voltage-controlled by the post-regulator 4 so that it becomes a predetermined output voltage, and the output voltage Vout is controlled by the load resistor R L The output is then displayed. Furthermore, the power transmission inductor Lt of inverter 2 and the power receiving inductor Lr of rectifier circuit 3 are positioned close together so as to be electromagnetically coupled with a coupling degree k.

[0021] In Figure 1, the inverter 2 comprises an input inductor Lc (choke coil), a switching MOS transistor Q1, a series capacitor Cs for charging and discharging, 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 the gate control voltage (gate control signal) v from the control circuit 20 is applied. gs1 The switching is performed by the switching MOS transistor Q1 according to the following. Here, the control circuit 20 controls the gate control voltage v, which is a PWM signal having a constant switching frequency fsw and a constant duty cycle. gs1 By generating a current and applying it to the gate (control terminal) of the switching MOS transistor Q1, the input voltage Vin is switched. The switched input voltage Vin is charged by the series capacitor Cs, then discharged and input to the series LC resonant circuit 21 (effectively an RLC resonant circuit when loss resistance is also considered), which consists of capacitors C2, Ct and inductors L2, Lt. Only the component at a predetermined resonant frequency is extracted, and the energy of the AC voltage is received by the receiving inductor Lr of the rectifier circuit 3 via the transmitting inductor Lt.

[0022] The inverter 2 configured as described above constitutes a load-independent EF class inverter, but the present invention is not limited to this, and may be configured as, for example, a load-independent E class inverter, as will be described later with reference to Figures 4A to 4G.

[0023] The rectifier circuit 3 is composed of 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 rectified by the diodes D1 and D2 after only the components of a predetermined resonance frequency are extracted by the series LC resonance circuit 31 composed of the power receiving inductor Lr and the power receiving capacitor Cr. Here, the resonance frequency of the series LC resonance circuit 31 of the rectifier circuit 3 and the resonance frequency of the series LC resonance circuit 21 of the inverter 2 are set to be substantially the same, for example. Next, the rectified voltage is smoothed by the smoothing capacitor Cf, and then the smoothed voltage is applied to the inductor L[[ID=!]] post and diode D post through the source and drain of the switching MOS transistor Q2 of the post regulator 4.

[0024] The rectifier circuit 3 configured as described above constitutes a current-driven class D rectifier circuit. However, the present invention is not limited to this, and as will be described later with reference to FIGS. 5A to 5F, for example, it may be configured with a rectifier circuit that is robust against reactance components.

[0025] The post regulator 4 includes a switching MOS transistor Q2, a smoothing inductor L post (choke coil), a half-wave rectifier diode D post and a smoothing capacitor C post and voltage detection divider resistors R d1 , R d2 and a current detection resistor R C2 and a differential amplifier 41 for amplifying the current detection voltage, a control circuit 40 for current control, and a gate driver 42.

[0026] 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) via the gate driver 42 from the control circuit 40, and then half-wave rectified by the diode D post . The rectified voltage is smoothed by the smoothing inductor L postand smoothing capacitor C post After being smoothed by a smoothing circuit consisting of the above, the output voltage Vout is equal to the load resistance R L The output voltage is output to the following. Here, the output voltage Vout is divided by the voltage divider resistors Rd1 and Rd2, and the divided voltages are input to the control circuit 40 as voltage detection voltages for the output voltage Vout. On the other hand, the load resistor R L The output current Iout flowing through the circuit is detected by the current sensing resistor RC2, and a detection voltage substantially proportional to the output current Iout is amplified by the differential amplifier 41 before being input to the control circuit 40.

[0027] In Embodiment 1, the post-regulator 4 operates as a buck converter in constant output voltage mode (CV mode: constant voltage mode), and the control circuit 40 controls the duty cycle of the PWM gate signal applied to the gate of the switching MOS transistor Q2 based on the voltage detection voltage so that the output voltage Vout becomes a predetermined voltage. The post-regulator 4 may also be configured as a boost converter or a buck / boost converter.

[0028] In the wireless power transmission system configured as described above, by using a load-independent Class E inverter 2 and a rectifier circuit 3 that does not depend on the reactance component, the resonant circuit 21 of the inverter 2 and the resonant circuit 31 of the rectifier circuit 3 are combined to electromagnetically couple, thereby enabling soft switching (ZVS) and a constant output (a constant output voltage Vout or a constant output current Iout) without changing other circuit parameters (input voltage Vin, switching frequency fsw, duty cycle, etc.) regardless of the range of load fluctuations.

[0029] Furthermore, by providing a post-regulator 4 after the rectifier circuit 3 and performing constant voltage control, the impedance seen from the inverter 2 to the downstream stage appears constant even with fluctuations in the coupling degree k, by controlling the duty cycle of the post-regulator 4. This enables soft switching (ZVS) and a constant output (a constant output voltage Vout or a constant output current Iout).

[0030] Here, we will provide a supplementary explanation as to why the output becomes constant when the impedance seen from inverter 2 to the downstream stage appears constant. In the wireless power transmission system shown in Figure 1, the gain G seen from the input terminal of inverter 2 to the downstream stage is expressed by the following equation.

[0031] G = Voeq / Vin (1)

[0032] Here, Voeq is the equivalent load resistance R when viewed from inverter 2 downstream. eq This is the effective value of the voltage applied to the load. Here, the equivalent load resistance R eq It can be expressed by the following equation.

[0033] R eq =(π 2 k 2 ω 2 LtLrD post 2 ) / 2R L (2)

[0034] Here, ω is the frequency of the AC voltage, and D post This is the duty cycle of post-regulator 4.

[0035] As is clear from equation (2), for example, when the degree of coupling k is relatively large, the duty cycle (ON time ratio) D of the post-regulator 4 post While reducing the coupling degree k, if the duty cycle (ON time ratio) of the post-regulator 4 is relatively small, D post By controlling it to increase the equivalent load resistance R, Leq This allows us to control the equivalent load resistance R to remain constant, thereby enabling us to control it to stay constant. Leq The voltage Voeq (equation (1)) applied to the terminal can be controlled to remain constant. In Embodiment 1, when the degree of coupling k fluctuates, the control circuit 40 calculates the duty cycle of the post-regulator 4 so that the output voltage Vout becomes a predetermined voltage (constant impedance), thereby controlling the output voltage Vout to be a predetermined voltage.

[0036] As described above, Embodiment 1 provides a wireless power transmission system that can keep the output voltage Vout constant even with respect to fluctuations in the degree of coupling k.

[0037] (Embodiment 2) Figure 2 is a circuit diagram showing an example configuration of a wireless power transmission system according to Embodiment 2. In Figure 2, the wireless power transmission system according to Embodiment 2 differs from the wireless power transmission system according to Embodiment 1 in Figure 1 in the following respects. (1) A pre-regulator 6, which includes a communication circuit 63 equipped with an antenna 63A and a control circuit 60, is inserted between the DC power supply 1 and the inverter 2. (2) Instead of the post-regulator 4, a post-regulator 4A is provided, which further includes a communication circuit 43 that performs wireless communication with a communication circuit 63. (3) The post-regulator 4A is connected to the control circuit 40 and further includes an operating unit 45 for the user to operate the switching of the operating mode. (4) The pre-regulator 6 is connected to the control circuit 60 and further includes an operating unit 65 for the user to operate the switching of the operating mode. The differences are explained below.

[0038] In Figure 2, the pre-regulator 6 and inverter 2 constitute a "wireless power transmission circuit," while the rectifier circuit 3 and post-regulator 4A constitute a "wireless power reception circuit."

[0039] The pre-regulator 6 consists of a switching MOS transistor Q3 and a smoothing inductor L. pre (Choke coil) and half-wave rectifier diode D pre And, smoothing capacitor C pre And, the current sensing resistor R C1 The system comprises a differential amplifier 61 for current detection voltage amplification, a control circuit 60 for current control, and a gate driver 62.

[0040] 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) via the gate driver 62 from the control circuit 60, and then the diode D pre The voltage is half-wave rectified by the smoothing inductor L. pre and smoothing capacitor C pre After being smoothed by a smoothing circuit consisting of the following, the output voltage is obtained from the current sensing resistor R C1 The output is sent to the input inductor Lc of inverter 2 via the current sensing resistor R. C1 The input current Iin flowing through it is determined by the current sensing resistor R. C1 The detection voltage, which is substantially proportional to the input current Iin, is amplified by the differential amplifier 61 and then input to the control circuit 60.

[0041] The pre-regulator 6 configured as described above operates in constant output current mode (CC mode: constant current mode) or in a predetermined constant duty cycle mode. In CC mode, the control circuit 60 operates in proportional component control mode and controls the duty cycle 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 constant duty cycle mode, the control circuit 60 sets the duty cycle of the PWM gate signal applied to the gate of the switching MOS transistor Q3 to a predetermined constant value.

[0042] As described in Embodiment 1, the post-regulator 4A can operate in either constant output voltage mode (CV mode) or constant output current mode (CC mode), and further includes a communication circuit 43 having an antenna 43A for wirelessly transmitting an operating mode switching signal to the control circuit 60 of the pre-regulator 6 when the user switches the operating mode using the operation unit 45. The control circuit 60 of the pre-regulator 6 is set to operate in constant duty cycle mode in response to the CV mode operating mode switching signal from the control circuit 40. On the other hand, the control circuit 60 of the pre-regulator 6 is set to operate in CC mode in response to the CC mode operating mode switching signal from the control circuit 40.

[0043] The operating mode switching signals indicating each operating mode are generated, for example, in the post-regulator 4A when the user performs a switching operation using the operation unit 45 connected to the control circuit 40. These operating mode switching signals are not transmitted or received at all times, but only when the operating mode is switched. Alternatively, the operating mode switching signals may be generated in the pre-regulator 6 when the user performs a switching operation using the operation unit 65 connected to the control circuit 60. In this case, the operating mode switching signals are transmitted from the control circuit 60 to the control circuit 40 via the communication circuits 63 and 43.

[0044] In Embodiment 2, (A) When the wireless power transmission system is in CC mode, Pre-regulator 6 operates in CC mode, and post-regulator 4A also operates in CC mode. (B) When the wireless power transmission system is in CV mode, The pre-regulator 6 operates in constant duty cycle mode (constant ratio mode), and the post-regulator 4A operates in CV mode.

[0045] Next, the operation of the CV mode in Embodiment 1 and the operation of the CC mode in Embodiment 2 will be described below with reference to Figure 3, etc. Figure 3 is an equivalent circuit diagram to illustrate that the output voltage can be kept constant in Embodiment 1.

[0046] In the CV mode of Embodiment 1, (1) When viewed from DC power supply 1 to the downstream stage, the output voltage is controlled in constant CV mode, (2) When viewed from inverter 2 downstream, the output current is controlled in a constant CC mode, (3) When viewed from the rectifier circuit 3 onward, the output voltage is controlled in a constant CV mode. (4) When viewed from the post-regulator 4 downstream, the output voltage is controlled in constant CV mode.

[0047] In Figure 3, when the equivalent circuit 7 of the inverter 2, viewed from the circuit downstream of the power transmission inductor Lt, is represented as a series circuit of the equivalent inductor Leq and the equivalent resistance Req, the equivalent resistance Req is expressed by the following equation, similar to equation (2).

[0048] R eq =(k 2 ω 2 LtLr) / (R L +r Lr )+r Lt ≒(π 2 k 2 ω 2 LtLrD post 2 ) / 2R L (3)

[0049] Here, r Lr is the loss resistance of the power receiving inductor Lr, and r Lt is the loss resistance of the power transmission inductor Lt. As is clear from equation (3), the entire wireless power transmission system according to Embodiment 1 is controlled in CV mode.

[0050] Next, in the CC mode of Embodiment 2, (1) When viewed from DC power supply 1 to the downstream stage, the output voltage is controlled in constant CV mode, (2) When viewed from the pre-regulator 6 downstream, the output current is controlled in a constant CC mode, (3) When viewed from inverter 2 downstream, the output voltage is controlled in constant CV mode. (4) When viewed from the rectifier circuit 3 to the subsequent stage, the output current is controlled in a constant CC mode. (5) When viewed from the post-regulator 4A downstream, the output current is controlled in a constant CC mode.

[0051] In other words, the entire wireless power transmission system according to Embodiment 2 is controlled in CC mode in this case.

[0052] As described above, according to Embodiment 2, in Embodiment 1, the load resistance R L While the output to the post regulator had a constant voltage (CV) characteristic, by adding a pre-regulator 6 and performing duty cycle control, the post-regulator 4A can output a constant current in CC mode. In this case, the duty cycle control of the post-regulator 4A is the same as in the case of the post-regulator 4 according to Embodiment 1. The input inductor L is one of the components of the pre-regulator 6. pre The pre-regulator 6 is closed off on the power transmission side in order to detect the current Iin flowing through the choke coil and perform duty cycle control to keep this current value constant.

[0053] The reason for adding communication between the power transmission and reception is that, with the addition of CC mode in addition to CV mode in the entire wireless power transmission system, it is necessary to synchronize the control between the power transmission and reception when switching between CC mode and CV mode. In CV mode of the wireless power transmission system, the duty cycle control of the pre-regulator 6 is stopped to a constant duty cycle, and the post-regulator 4A is operated in CV mode as a circuit similar to that in Embodiment 1 to control the duty cycle. In CC mode of the wireless power transmission system, the pre-regulator 6 and post-regulator 4A are operated in CC mode.

[0054] The configuration of Embodiment 2, in addition to the effects of Embodiment 1, which provided load-independent soft switching and support for fluctuations in coupling degree k, allows for charging in CC mode or CV mode (when the load is a secondary battery). Since communication between the transmitting and receiving power is only required when switching between CC mode and CV mode, there is no risk of excessive output voltage or current due to communication interruption.

[0055] (modified version) Next, a modified version of the inverter that can be used in place of inverter 2 in Figures 1 and 2 will be described below.

[0056] (Variation 1 of Inverter 2) Figure 4A is a circuit diagram showing an example configuration of inverter 2A according to modification 1 of inverter 2 in Figures 1 and 2. In Figure 4A, 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.

[0057] 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 switched voltage is filtered to show only the predetermined resonant frequency components by an LC resonant circuit consisting 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 Class E inverter and can operate in ZVS mode and CV mode.

[0058] (Variation 2 of Inverter 2) Figure 4B is a circuit diagram showing an example configuration of inverter 2B related to a modified example 2 of inverter 2 in Figures 1 and 2. In Figure 4B, 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.

[0059] In the inverter 2B 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 switched voltage is filtered to show only the predetermined resonant frequency components by an LC resonant circuit consisting of capacitors Cs, C2, Ct, inductor L2, and 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 constitutes a load-independent Class E inverter and can operate in ZVS mode and CC mode.

[0060] (Variation 3 of Inverter 2) Figure 4C is a circuit diagram showing an example configuration of inverter 2C related to modification 3 of inverter 2 in Figures 1 and 2. In Figure 4C, 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.

[0061] 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 inductors Lc and Ls, and then switched by the switching MOS transistor Q1. The switched voltage is filtered to include only predetermined resonant frequency components by an LC resonant circuit consisting 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 inverse E class inverter and can operate in ZCS mode or CC mode.

[0062] (Variation 4 of Inverter 2) Figure 4D is a circuit diagram showing an example configuration of inverter 2D related to modification 4 of inverter 2 in Figures 1 and 2. In Figure 4D, inverter 2D consists of inductors L1 and Lc, a switching MOS transistor Q1, a capacitor C1, a power transmission capacitor Ct, and a voltage divider resistor R d1 ,R d2 It is configured to include a feedback circuit consisting of a capacitor Cf and an inductor Lf, a power transmission capacitor Ct, and a power transmission inductor Lt.

[0063] In the inverter 2D configured as described above, the input voltage Vin from the DC power supply 1 is connected to the voltage divider resistor R d1 ,R d2 The divided voltage obtained by this process becomes the gate voltage to the switching MOS transistor Q1 and is also fed back to the power transmission inductor Lt via the inductor Lf of the feedback circuit. The input voltage Vin is input to the switching MOS transistor Q1 via inductors Lc and L1, and then switched by the switching MOS transistor Q1. The switched voltage is filtered by a resonant circuit consisting of capacitor Ct and inductor Lt via capacitor C1 to contain only a predetermined resonant frequency component, and then transmitted from the power transmission inductor Lt. Here, the inverter 2D constitutes a load-independent inverse E class anticoupled oscillator inverter and can operate in ZCS mode and CV mode.

[0064] (Variation 5 of Inverter 2) Figure 4E is a circuit diagram showing an example configuration of inverter 2E according to modification 5 of inverter 2 in Figures 1 and 2. In Figure 4E, inverter 2E is configured to include inductors L1, Lc, a switching MOS transistor Q1, a capacitor C1, a power transmission capacitor Ct, and a power transmission inductor Lt.

[0065] 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 inductors Lc and L1, and then switched by the switching MOS transistor Q1. The switched voltage is filtered by a resonant circuit consisting of a power transmission capacitor Ct and a power transmission inductor Lt via inductor L1 and capacitor C1, so that only a predetermined resonant frequency component is filtered out, and then the power is transmitted from the power transmission inductor Lt. Here, the inverter 2E constitutes a load-independent inverse E class inverter and can operate in ZCS mode and CV mode.

[0066] (Variation 6 of Inverter 2) Figure 4F is a circuit diagram showing an example configuration of inverter 2F according to modification 6 of inverter 2 in Figures 1 and 2. In Figure 4F, inverter 2F is configured to include inductors Lc and Ls, capacitor Cs, switching MOS transistor Q1, capacitor C1, power transmission capacitor Ct, and power transmission inductor Lt.

[0067] 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 inductors Lc and Ls, and then switched by the switching MOS transistor Q1. The switched voltage is filtered to show only the predetermined resonant frequency components by a resonant circuit consisting of a power transmission capacitor Ct and a power transmission inductor Lt via capacitor Cs, inductor Ls, and capacitor C1, and then transmitted from the power transmission inductor Lt. Here, the inverter 2F constitutes a load-independent Class E inverter and can operate in ZVS mode and CC mode.

[0068] (Variation 7 of Inverter 2) Figure 4G is a circuit diagram showing an example configuration of inverter 2G, which is a modified example 7 of inverter 2 in Figures 1 and 2. In Figure 4G, inverter 2G is a push-pull type inverter modified from inverter 2B in Figure 4B, and compared to the configuration of inverter 2B, it further includes a switching MOS transistor Q1a, a series capacitor Csa, inductors Lia, L2a, and capacitor C2a. Note that the gate control voltage v from the control circuit 20 controls the switching MOS transistor Q1a. gs1a Switching is performed by [this method].

[0069] In the inverter 2G configured as described above, the input voltage Vin from the DC power supply 1 is input to switching MOS transistors Q1 and Q1a, respectively, via input inductors Li and Lia, and then switched by the switching MOS transistors Q1 and Q1a. Each switched voltage is filtered to show only the predetermined resonant frequency components by an LC resonant circuit consisting of capacitors Cs, C2, Ct and inductor L2 and power transmission inductor Lt, and an LC resonant circuit consisting of capacitors Csa, C2a and inductor L2a and power transmission inductor Lt, respectively, and then the filtered AC voltage is transmitted from power transmission inductor Lt via capacitor Ct. Here, inverter 2G constitutes a push-pull type load-independent EF class inverter and can operate in ZVS mode and CC mode.

[0070] Next, a modified version of the rectifier circuit that can be used in place of the rectifier circuit 3 in Figures 1 and 2 will be described below.

[0071] (Modified example 1 of rectifier circuit 3) Figure 5A is a circuit diagram showing an example configuration of a rectifier circuit 3A according to modification 1 of the rectifier circuit 3 in Figures 1 and 2. In Figure 5A, 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.

[0072] In the rectifier circuit 3A configured as described above, the AC voltage is received by the receiving inductor Lr, then half-wave rectified by diodes D1 and D2 via the receiving capacitor Cr, and then smoothed by the smoothing capacitor Cf before being rectified against the load resistor R L The output is then displayed. Here, the rectifier circuit 3A constitutes a half-bridge type current-driven Class D rectifier circuit.

[0073] (Modified version 2 of rectifier circuit 3) Figure 5B is a circuit diagram showing an example configuration of a rectifier circuit 3B related to a modified example 2 of the rectifier circuit 3 in Figures 1 and 2. In Figure 5B, the rectifier circuit 3B is composed of a power receiving inductor Lr, a power receiving capacitor Cr, diodes D1 to D4, and a smoothing capacitor Cf.

[0074] In the rectifier circuit 3B configured as described above, the AC voltage is received by the receiving inductor Lr, then full-wave rectified by diodes D1 to D4 via the receiving capacitor Cr, and then smoothed by the smoothing capacitor Cf before being applied to the load resistor R L The output is then displayed. Here, the rectifier circuit 3B constitutes a full-bridge type current-driven Class D rectifier circuit.

[0075] (Modified example 3 of rectifier circuit 3) Figure 5C is a circuit diagram showing an example configuration of a rectifier circuit 3C related to a modified example 3 of the rectifier circuit 3 in Figures 1 and 2. In Figure 5C, 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.

[0076] In the rectifier circuit 3C configured as described above, the AC voltage is received by the receiving inductor Lr and then smoothed by the smoothing capacitor Cfa. The smoothed voltage is full-wave rectified by diodes D1 and D2, and then smoothed by the smoothing inductor Lf and smoothing capacitor Cf and then passed to the load resistor R L The output is then displayed. Here, the rectifier circuit 3C constitutes a half-bridge type voltage-driven Class D rectifier circuit.

[0077] (Modified example 4 of rectifier circuit 3) Figure 5D is a circuit diagram showing an example configuration of a rectifier circuit 3D related to a modified example 4 of the rectifier circuit 3 in Figures 1 and 2. In Figure 5D, the rectifier circuit 3D is composed of a power receiving inductor Lr, a smoothing capacitor Cr, diodes D1 to D4, a smoothing inductor Lf, and a smoothing capacitor Cf.

[0078] In the rectifier circuit 3D configured as described above, the AC voltage is received by the receiving inductor Lr and then smoothed by the smoothing capacitor Cr. The smoothed voltage is full-wave rectified by diodes D1 to D4, and then smoothed by the smoothing inductor Lf and smoothing capacitor Cf and then passed to the load resistor R L The output is then displayed. Here, the rectifier circuit 3D constitutes a full-bridge voltage-driven Class D rectifier circuit.

[0079] (Modified example 5 of rectifier circuit 3) Figure 5E is a circuit diagram showing an example configuration of a rectifier circuit 3E related to modification 5 of the rectifier circuit 3 in Figures 1 and 2. In Figure 5E, the rectifier 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.

[0080] In the rectifier circuit 3E configured as described above, the AC voltage is received by the receiving inductor Lr and then filtered by a resonant circuit having a predetermined resonant frequency, consisting of the inductor Lr and capacitors Cr and Cs. The filtered AC voltage is then subjected to a predetermined gate control voltage v gs4 After being switched by the switching MOS transistor Q4, it is smoothed by the smoothing inductor Lc and smoothing capacitor Cf, and then the load resistor R L The output is then displayed. Here, the rectifier circuit 3E constitutes a load-independent Class E rectifier circuit.

[0081] (Modified version 6 of rectifier circuit 3) Figure 5F is a circuit diagram showing an example configuration of a rectifier circuit 3F related to a modified example 6 of the rectifier circuit 3 in Figures 1 and 2. In Figure 5F, the rectifier circuit 3F is composed of 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.

[0082] In the rectifier circuit 3F configured as described above, the AC voltage is received by the receiving inductor Lr and then filtered by a resonant circuit having a predetermined resonant frequency, consisting of inductor Lr, receiving capacitor Cr, inductor L2, and capacitor C2. The filtered AC voltage is then subjected to a predetermined gate control voltage v gs4 After being switched by the switching MOS transistor Q4, it is smoothed by the smoothing inductor Lc and smoothing capacitor Cf, and then the load resistor R L The output is then displayed. Here, the rectifier circuit 3F constitutes a load-independent EF class rectifier circuit.

[0083] (Other variations) In the above embodiments and modifications, the post-regulators 4, 4A and pre-regulator 6 may be, for example, a boost DC-DC converter, a buck DC-DC converter, or a buck-boost DC-DC converter.

[0084] In the embodiments and modifications described above, MOS transistors Q1 to Q4 and Q1a are used, but the present invention is not limited to these, and other types of transistors, such as bipolar transistors, may be used.

[0085] In the embodiments described above, the communication circuits 43 and 63 are wireless communication circuits using wireless communication, but the present invention is not limited to this and may also be wired communication circuits using wired communication. [Industrial applicability]

[0086] As described in detail above, the present invention provides a wireless power transmission system capable of keeping the output voltage or output current constant despite fluctuations in the coupling degree k, a wireless power transmission circuit for the wireless power transmission system, and a wireless power receiving circuit. This wireless power transmission system can be applied to power supply to mobile vehicles such as AGVs and EVs, and can also be applied to power supply to slip rings (rotating bodies) used in manufacturing line pallets or robot arms. [Explanation of Symbols]

[0087] 1 DC power supply 2 Inverters 3 Rectifier circuit 4.4A Post Regulator 5 load 6 Pre-regulator 7. Equivalent circuit of the next stage 20 Control circuits 21 Resonant circuit 31 Resonant circuit 40 Control circuits 41 Differential Amplifier 42 Gate Drivers 43 Communication Circuit 43A Antenna 45 Operation section 60 Control circuits 61 Differential Amplifier 62 Gate Drivers 63 Communication Circuit 63A Antenna 65 Operation section 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 Lpre, Lr, Ls, Lt, L51~L63 Inductors Q1-Q4, Q51, Q61 MOS transistors R C1 ,RC2 ,R d1 ,R d2 ,Req,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, The aforementioned wireless power transmission circuit is An inverter comprising a first LC resonant circuit including a power transmission inductor, wherein the inverter switches the input voltage at a predetermined switching frequency and a predetermined duty cycle, and transmits the switched AC voltage from the power transmission inductor, The aforementioned wireless power receiving circuit is A rectifier circuit including a second LC resonant circuit which includes a receiving inductor electromagnetically coupled to the transmitting inductor, the rectifier circuit which rectifies the AC voltage received by the receiving inductor and outputs a rectified voltage, The system includes a first regulator that detects the 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. Wireless power transmission system.

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

3. The inverter includes a Class E inverter, an inverse Class E inverter, an EF class inverter, or an inverse Class E anti-coupled oscillator 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. The wireless power transmission system according to claim 1.

4. The wireless power transmission circuit further includes a second regulator provided in front of the inverter, The second regulator includes a second current control transistor. The second regulator described above is (A) A constant current mode in which the output current from the second regulator is detected, and the second current control transistor is controlled based on the detected output current to control the input voltage so that the output current becomes a predetermined current, and the output current is output to the inverter, (B) A constant ratio mode in which the input voltage is controlled by controlling the second current control transistor with a constant duty cycle, and the output voltage is output to the inverter, It has an operating mode, The first regulator is (A) In addition to a constant voltage mode in which the output voltage from the first regulator is detected and the rectified voltage is controlled based on the detected output voltage so that the output voltage becomes a predetermined voltage, (B) The device has a constant current mode operating mode that detects the 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, The system includes a first communication circuit that transmits an operating mode switching signal to the second regulator or receives an operating mode switching signal from the second regulator when selectively switching between the constant voltage mode and the constant current mode. The second regulator further, The system includes a second communication circuit that transmits an operating mode switching signal to the first regulator or receives an operating mode switching signal from the first regulator when selectively switching between the constant ratio mode and the constant current mode. When the first regulator operates in the constant voltage mode, the second regulator operates in the constant ratio mode. When the first regulator operates in the constant current mode, the second regulator is configured to operate in the constant current mode. A wireless power transmission system according to any one of claims 1 to 3.

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

6. A wireless power transmission circuit for a wireless power transmission system according to any one of claims 1 to 3, The wireless power transmission circuit includes the inverter, Wireless power transmission circuit.

7. A wireless power receiving circuit for a wireless power transmission system according to any one of claims 1 to 3, The wireless power receiving circuit comprises the rectifier circuit and the first regulator. Wireless power receiving circuit.

8. A wireless power transmission circuit for a wireless power transmission system according to claim 4, The wireless power transmission circuit comprises the second regulator and the inverter. Wireless power transmission circuit.

9. A wireless power receiving circuit for a wireless power transmission system according to claim 4, The wireless power receiving circuit comprises the rectifier circuit and the first regulator. Wireless power receiving circuit.

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