Contactless Power Transmission System

Abstract

To provide a contactless electric power transmission system capable of performing appropriate power transmission by independent communication control and power control on the power reception side.SOLUTION: A contactless electric power transmission system 1 comprises an electric power reception device 4 and a controller 17. The electric power reception device 4 receives electric power transmitted contactlessly between itself and an electric power transmission device 2. In a coupling section in which a degree of coupling between a primary side coil of the electric power transmission device 2 and a secondary side coil of the electric power reception device 4 is equal to or larger than a predetermined degree, the controller 17 sets communication sections in which the degree of coupling is relatively small and electric power transmission sections in which the degree of coupling is relatively large. When the secondary side coil exists in the first communication section of the coupling section, the controller 17 transmits information on electric power transmission in the electric power transmission section from the electric power reception device 4 to the electric power transmission device 2 by using communication between the electric power transmission device 2 and the electric power reception device 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a contactless power transfer system. [Background technology]

[0002] In recent years, research and development has been conducted into charging vehicles equipped with secondary batteries that contribute to energy efficiency, in order to ensure that more people have access to affordable, reliable, sustainable and advanced energy. Conventionally, in a contactless power transmission system that supplies power to a vehicle from outside the vehicle by contactless power transmission, a system is known in which communication is performed between the power transmitting side and the power receiving side by superimposing a communication signal on a power supply signal transmitted from the power transmitting side to the power receiving side (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-247807 Summary of the Invention [Problem to be solved by the invention]

[0004] In a technology for charging and supplying power to a vehicle equipped with a secondary battery, when power is transmitted to a moving vehicle in a non-contact manner, the time required for the vehicle to pass a power transmitting coil installed on the roadway is extremely short, on the order of 0.01 seconds. As a result, in a non-contact power transmission system such as the above-mentioned conventional technology, for example, there is a risk of anomalies occurring, such as the vehicle passing by the power transmitting coil before communication between the power transmitting side and the power receiving side is established, communication between the power transmitting side and the power receiving side becoming unstable and power transmission not being established, or excessive power being supplied.

[0005] An object of the present invention is to provide a contactless power transfer system that can perform appropriate power transfer through independent communication control and power control on the power receiving side, thereby contributing to energy efficiency. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the above object, the present invention employs the following aspects. (1): A contactless power transfer system according to one aspect of the present invention (e.g., contactless power transfer system 1 in the embodiment) includes a power receiving device (e.g., power receiving device 4 in the embodiment) having a power receiving side coil (e.g., secondary side coil 15a in the embodiment) that transfers and receives power transferred contactlessly between the power receiving side coil (e.g., primary side coil 8a in the embodiment) of a power transmitting device (e.g., power transmitting device 2 in the embodiment), and a control device (e.g., control device 17 in the embodiment) that controls the power receiving device, and the control device controls the power transmitting side coil (e.g., primary side coil 8a in the embodiment). In a coupling section in which the degree of coupling with the power receiving side coil is equal to or greater than a predetermined value, a communication section in which the degree of coupling is relatively small (for example, a communication section CS, a first communication section CS1, and a second communication section CS2 in the embodiment) and a power transmission section in which the degree of coupling is relatively large (for example, a power transmission section TS in the embodiment) are set, and when the power receiving side coil is in the first communication section of the coupling section, information regarding power transmission in the power transmission section is transmitted from the power receiving device to the power transmitting device through communication between the power transmitting device and the power receiving device. and the information regarding the power transmission is set to include at least key information and information regarding the required frequency of the power transmission. .

[0007] (2): In the contactless power transmission system described in (1) above, the control device may set the timing of communication between the power transmitting device and the power receiving device in the communication section depending on the movement state of the power receiving coil.

[0008] (3) In the wireless power transmission system described in (1) or (2) above, the control device The information regarding the power transmission may be set to include at least key information and information regarding the required frequency of the power transmission, and the information regarding the power transmission may be sent from the power receiving device to the power transmitting device in the first communication section, causing the power transmitting device to perform the power transmission at the required frequency in accordance with the matching of the key information in the power transmission section.

[0009] (4): The contactless power transmission system described in (3) above includes a communication device (e.g., an in-vehicle communication device 18 in the embodiment) whose communication with an externally located communication device (e.g., a roadside communication device Ma in the embodiment) is controlled by the control device, and the control device may transition the power transmission device from a stopped state to a standby state for receiving the information regarding the power transmission by acquiring the key information through communication between the communication device and the communication device before the receiving coil reaches the coupling section, and may maintain the standby state for receiving the information until the matching of the key information is completed.

[0010] (5): In the contactless power transfer system described in (4) above, the control device may set the reception standby state to a short-circuit state of the power transmitting side coil, and the communication between the power transmitting device and the power receiving device may be performed using a voltage induced in the power transmitting side coil by a magnetic field generated in the power receiving side coil by a current switching operation of the power receiving device. 。 [Effects of the Invention]

[0011] According to the above (1), by providing a control device that sends information about power transmission from the power receiving device to the power transmitting device in the communication section prior to arriving at the power transmission section, it is possible to ensure the desired power and transmission efficiency. For example, even if the speed of a mobile object equipped with a power receiving device is high and the time it takes to pass through the power transmission section is short, the control device can quickly start power transmission in the power transmission section by sending information about power transmission before arriving at the power transmission section.

[0012] In the case of (2) above, the control device sets the timing (period, number of times, etc.) of communication in the communication section depending on the moving state, such as the speed, of the mobile body equipped with the power receiving device, so that communication can be completed properly in the communication section and an increase in power consumption can be suppressed by preventing excessive communication from being performed.

[0013] (3) above or (6) In this case, the desired power and transmission efficiency can be ensured by providing a control device that sends information about the required frequency for power transmission to the power transmitting device. For example, even if the coupling coefficient decreases due to the vehicle's ground clearance and the installation layout of the power receiving device, which are related to the distance between the power transmitting coil and the power receiving coil, the decrease in power and transmission efficiency can be suppressed by using a required frequency that offsets the fluctuation in mutual inductance.

[0014] In the case of (4) above, by providing a control device that transitions the power transmitting device to a reception standby state before the power transmitting device reaches the coupling section, it is possible to quickly receive and verify the key information in the communication section. Since the power transmitting device is in a stopped state before the control device acquires the key information, it is possible to suppress an increase in standby power consumption.

[0015] In the case of (5) above, the communication of information due to power transmission from the power receiving device to the power transmitting device can be detected by the voltage and current of the power transmitting coil. By performing communication between the power receiving coil and the power transmitting coil, the system configuration can be prevented from becoming complicated compared to, for example, when an additional communication device is provided for each side. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing a configuration of a contactless power transmission system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing details of the configuration of a contactless power transmission system according to an embodiment of the present invention. [Figure 3] 1 is a diagram showing the configuration of a power transmitting unit and a power receiving unit of a contactless power transfer system according to an embodiment of the present invention. [Figure 4] 10A and 10B are diagrams showing examples of correspondence relationships between the amount of relative movement between the primary coil of the power transmitting device and the secondary coil of the power receiving device and the output of power transmission at each voltage according to an embodiment of the present invention. [Figure 5] 10 is a diagram showing an example of a correspondence relationship between the amount of relative movement between the primary coil of the power transmitting device and the secondary coil of the power receiving device and the efficiency of power transmission in an embodiment of the present invention. [Figure 6] 3A and 3B are diagrams showing an example of communication and power transmission operations accompanying movement of a moving body (vehicle) in an embodiment of the present invention. [Figure 7] 4 is a flowchart showing a power receiving side process of the contactless power transmission system according to the embodiment of the present invention. [Figure 8] 4 is a flowchart showing a power transmission side process of the contactless power transmission system according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, a contactless power transfer system according to an embodiment of the present invention will be described with reference to the accompanying drawings. 1 and 2 are diagrams showing the configuration of a contactless power transfer system 1 according to an embodiment. Fig. 3 is a diagram showing the configurations of a power transmitting unit 8 and a power receiving unit 15 of the contactless power transfer system 1 according to an embodiment. A contactless power transfer system 1 according to the embodiment supplies power to a moving body such as a vehicle from outside the moving body by contactless power transfer. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, a fuel cell vehicle, or other electrically powered vehicle.

[0018] (contactless power transmission system) 1 and 2, a contactless power transfer system 1 according to an embodiment includes, for example, a power transmitting device 2 installed on a vehicle's running path or the like, a drive control device 3 and a power receiving device 4 mounted on a moving body such as a vehicle, and a communication system M. Note that the contactless power transfer system 1 according to an embodiment may include at least only the components mounted on the moving body (for example, the drive control device 3 and the power receiving device 4), or contactless power transfer may be performed by combining components external to the moving body (for example, the power transmitting device 2 and the communication system M) with the contactless power transfer system 1 mounted on the moving body.

[0019] The communication system M includes, for example, at least one roadside communication device Ma and a communication control device Mb. The communication system 1 constitutes at least a part of a system for electronically collecting tolls, such as an ETC (Electronic Toll Collection System) on a toll road.

[0020] The roadside communication device Ma is disposed, for example, at a predetermined distance upstream of a coupling section (communication section and power transmission section) described later on a roadway or the like along which the vehicle travels. The roadside communication device Ma includes an antenna for wireless communication and wirelessly communicates with an on-board communication device 18 (described later) mounted on a mobile object such as a vehicle. For example, when the roadside communication device Ma acquires information necessary for billing and settlement for power transmission from the power transmission device 2 to the mobile object such as a vehicle from the on-board communication device 18, the roadside communication device Ma transmits key information necessary for starting power transmission and information about the installation of the power transmission device 2 to the on-board communication device 18. The information necessary for billing and settlement is information specific to the mobile object such as a vehicle, such as the presence or absence and identifier of an IC card or on-board transponder for toll collection. The key information is, for example, information generated and updated at a predetermined interval so as to be different for each authorized mobile object (i.e., a vehicle permitted to perform power transmission) passing through a predetermined power transmission section. The key information is information necessary for the power transmission device 2 to authenticate a power receiving device 4 (described later) of the mobile object such as a vehicle. The information relating to the installation of the power transmission device 2 is, for example, information such as the installation intervals of the plurality of power transmission units 8, which will be described later.

[0021] The communication control device Mb controls the operation of all roadside communication devices Ma that are associated with it in advance. The communication control device Mb is a software function unit that functions when a processor such as a CPU (Central Processing Unit) executes a predetermined program. The software function unit is an ECU that includes a processor such as a CPU, a ROM (Read Only Memory) that stores programs, a RAM (Random Access Memory) that temporarily stores data, and electronic circuits such as a timer. At least a part of the communication control device Mb may be an integrated circuit such as an LSI (Large Scale Integration). For example, the communication control device Mb attempts to acquire information necessary for billing and settlement by communicating with the roadside communication device Ma and the in-vehicle communication device 18 of a mobile body such as a nearby vehicle at a predetermined period, etc. When the communication control device Mb acquires the information necessary for billing and settlement from the in-vehicle communication device 18 and confirms that electronic settlement is possible, it transmits permission information indicating that electronic settlement is possible and key information necessary for starting power transmission to the in-vehicle communication device 18. When the communication control device Mb transmits key information from the roadside communication device Ma to the in-vehicle communication device 18, it transmits the same key information to the power transmission side control device 9 described below.

[0022] The power transmission device 2 includes, for example, a power supply unit 6, a transmission power conversion unit 7, a power transmission unit 8, and a power transmission side control device 9. Note that the power transmission device 2 may include at least a plurality of power transmission units 8 in a predetermined coupling section on a vehicle travel path or the like. The power supply unit 6 includes, for example, an AC power supply such as a commercial power supply, an AC-DC converter that converts AC power into DC power, and a power smoothing capacitor. The power supply unit 6 converts AC power supplied from the AC power supply into DC power using the AC-DC converter.

[0023] The transmission power conversion unit 7 includes, for example, an inverter that converts DC power into AC power. The inverter of the transmission power conversion unit 7 includes, for example, a bridge circuit formed by a plurality of switching elements and rectifying elements bridge-connected in two phases, and a voltage-smoothing capacitor. Each switching element is, for example, a transistor such as a SiC (Silicon Carbide) MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The plurality of switching elements are high-side arm and low-side arm transistors 7a and 7b that form a pair in each phase. The rectifying element is, for example, a freewheeling diode connected in parallel to each of the transistors 7a and 7b. A voltage-smoothing capacitor 7c is connected in parallel to the bridge circuit.

[0024] The power transmitting unit 8 transmits power by changing a high-frequency magnetic field, for example, through magnetic field coupling such as magnetic resonance or electromagnetic induction. As shown in Fig. 3, the power transmitting unit 8 includes a resonant circuit formed by, for example, a primary coil 8a, a primary resistor 8b, and a primary capacitor 8c connected in series. The power transmitting unit 8 also includes a sensor, such as a current sensor, that detects the current It flowing through the resonant circuit.

[0025] The power transmission control device 9 comprehensively controls the power transmission devices 2. The power transmission control device 9 is a software function unit that functions when a processor such as a CPU (Central Processing Unit) executes a predetermined program. The software function unit is an ECU that includes a processor such as a CPU, a ROM (Read Only Memory) that stores programs, a RAM (Random Access Memory) that temporarily stores data, and electronic circuits such as a timer. At least a part of the power transmission control device 9 may be an integrated circuit such as an LSI (Large Scale Integration).

[0026] For example, the power transmission side control device 9 transmits power to the vehicle's power receiving device 4 by controlling the on (conduction) and off (cutoff) switching of each switching element of the power transmission power conversion unit 7 according to a preset drive frequency or information on a required frequency received from the power receiving device 4. For example, when the power transmitting side control device 9 receives key information from the communication control device Mb, it recognizes that the same key information has been transmitted from the roadside communication device Ma to the in-vehicle communication device 18 of the mobile object, and transitions the power transmitting device 2 from a stopped state to a reception standby state. The stopped state of the power transmitting device 2 is a state in which the switching operation of the power transmitting power conversion unit 7 is stopped, for example, by maintaining each switching element of the power transmitting power conversion unit 7 in an off (blocked) state. The reception standby state of the power transmitting device 2 is a state in which information transmission from the power receiving device 4 of the mobile object, such as a vehicle, is detected. The reception standby state of the power transmitting device 2 is, for example, a short-circuit state of the power transmitting power conversion unit 7.

[0027] When the power transmission power converter 7 is short-circuited, the power transmission side control device 9 short-circuits the primary coil 8a by turning on the low-side arm transistor 7b of each phase. As a result, when the primary power transmission device 2 is viewed from the secondary power reception device 4, the impedance of the primary side becomes very large. However, when a magnetic field is generated by the secondary coil 15a of the power reception device 4 during PING transmission (described later), communication from the power reception device 4 is detected by the voltage induced in the primary coil 8a of the power transmission device 2.

[0028] For example, when the power transmitting side control device 9 receives information such as key information and a requested frequency for power transmission from the power receiving device 4, it compares the key information received from the communication control device Mb with the key information received from the power receiving device 4. If the key information matches, the power transmitting side control device 9 transitions the power transmitting device 2 from a reception standby state to a power transmission state. The power transmission state of the power transmitting device 2 is, for example, a state in which power is transmitted at the requested frequency of the power receiving device 4.

[0029] 1 and 2, a drive control device 3 of a moving body such as a vehicle includes, for example, a power storage device 11, a power storage voltage converter 12, a power converter 13, and a rotating electric machine 14. A power receiving device 4 of the moving body includes, for example, a power receiving unit 15 and a power receiving power converter 16. The drive control device 3 and the power receiving device 4 include, for example, a common control device 17. The control device 17 includes, for example, an on-board communication device 18. For example, in the case of an electric vehicle or the like that is driven using the power storage device 11 as a power source, the drive control device 3 does not need to include the storage voltage conversion unit 12. For example, in the case of a hybrid vehicle or the like that is driven using the power storage device 11 and an internal combustion engine as power sources, the drive control device 3 may include the storage voltage conversion unit 12.

[0030] The power storage device 11 is connected to a power storage voltage converter 12. The power storage device 11 is charged by power transmitted contactlessly from a power transmission device 2 outside the vehicle. The power storage device 11 exchanges power with a rotating electric machine 14 via the power storage voltage converter 12 and the power converter 13. The power storage device 11 includes a battery such as a lithium ion battery, a current sensor that detects the current of the battery, and a voltage sensor that detects the voltage of the battery. For example, in an electric vehicle or the like that does not include the storage voltage conversion unit 12, the power storage device 11 is connected to the power conversion unit 13 and the received power conversion unit 16, which will be described later.

[0031] The storage voltage conversion unit 12 is connected to the power conversion unit 13 and the received power conversion unit 16. The storage voltage conversion unit 12 includes, for example, a voltage controller that performs bidirectional voltage conversion, that is, step-up and step-down. The voltage controller converts input power and output power by bidirectional voltage conversion when charging and discharging the power storage device 11. The voltage controller of the storage voltage conversion unit 12 includes, for example, a pair of first reactors, a first element module, and a capacitor for voltage smoothing.

[0032] The pair of first reactors 12a, 12a are magnetically coupled to each other with opposite polarities to form a composite reactor, and are connected to a connection point between the high-side arm and the low-side arm of each phase of the first element module. The first element module includes a first bridge circuit formed by a plurality of switching elements and rectifying elements bridge-connected in two phases, for example. Each switching element is a transistor such as a SiC MOSFET. The plurality of switching elements are high-side arm and low-side arm transistors 12b and 12c that form a pair in each phase. The rectifying elements are, for example, freewheeling diodes connected in parallel to each of the transistors 12b and 12c. A voltage smoothing capacitor 12d is connected in parallel to the power storage device 11. The storage voltage converter 12 includes a resistor 12e and a transistor 12f connected in series, and the resistor 12e and the transistor 12f are connected in parallel to a first bridge circuit.

[0033] The pair of first reactors 12a and the first element module of the voltage controller perform voltage conversion by so-called two-phase interleaving. In two-phase interleaving, one cycle of switching control of the first-phase transistors 12b and 12c of the two-phase transistors 12b and 12c connected to the pair of first reactors 12a is shifted by half a cycle from one cycle of switching control of the second-phase transistors 12b and 12c.

[0034] The power conversion unit 13 is connected to the rotating electric machine 14. The power conversion unit 13 includes, for example, a power converter that converts between DC power and AC power. The power converter includes, for example, a second element module and a capacitor for voltage smoothing. The second element module includes, for example, a second bridge circuit formed by a plurality of switching elements and rectifying elements bridge-connected in three phases. Each switching element is, for example, a transistor such as a SiC MOSFET. The plurality of switching elements are high-side arm and low-side arm transistors 13a and 13b that form a pair in each phase. The rectifying elements are, for example, freewheeling diodes connected in parallel to each of the transistors 13a and 13b. A voltage smoothing capacitor 13c is connected in parallel to the second bridge circuit.

[0035] The second element module controls the operation of the rotating electric machine 14 by receiving and sending electric power. For example, when the rotating electric machine 14 is powered, the second element module converts DC power input from the positive and negative DC terminals 13p, 13n into three-phase AC power and supplies the three-phase AC power from the three-phase AC terminals 13d to the rotating electric machine 14. The second element module generates a rotational driving force by sequentially commutating the current to the three-phase stator windings of the rotating electric machine 14. For example, during regeneration of the rotating electric machine 14, the second element module converts three-phase AC power input from the three-phase stator windings into DC power by driving the switching elements of each phase to turn on (conducting) and off (disconnecting) in synchronization with the rotation of the rotating electric machine 14. The second element module can supply the DC power converted from the three-phase AC power to the power storage device 11 via the storage voltage converter 12.

[0036] The rotating electric machine 14 is, for example, a three-phase AC brushless DC motor provided for driving a vehicle. The rotating electric machine 14 includes a rotor having a permanent magnet for a field, and a stator having three-phase stator windings that generate a rotating magnetic field that rotates the rotor. The three-phase stator windings are connected to three-phase AC terminals 13d of the power conversion unit 13. The rotating electric machine 14 generates rotational driving force by power running using the electric power supplied from the electric power conversion unit 13. For example, if the rotating electric machine 14 can be connected to the wheels of a vehicle, it generates driving force by power running using the electric power supplied from the electric power conversion unit 13. The rotating electric machine 14 may generate electric power by performing regenerative operation using rotational power input from the wheels of the vehicle. If the rotating electric machine 14 can be connected to an internal combustion engine of the vehicle, it may generate electric power using the power of the internal combustion engine.

[0037] The power receiving unit 15 is connected to the receiving power conversion unit 16. The power receiving unit 15 receives power by changes in the high-frequency magnetic field transmitted from the power transmitting unit 8, for example, through magnetic field coupling such as magnetic resonance or electromagnetic induction. As shown in FIG. 3, the power receiving unit 15 includes a resonant circuit formed by, for example, a secondary coil 15a, a secondary resistor 15b, and a secondary capacitor 15c connected in series. The power receiving unit 15 also includes a sensor such as a current sensor that detects a current Ir flowing through the resonant circuit.

[0038] 1 and 2 is connected to the power conversion unit 13. The receiving power conversion unit 16 includes a so-called full-bridgeless (or bridgeless and totem-pole) power factor correction (PFC) circuit that converts AC power into DC power. The so-called bridgeless PFC is a PFC that does not include a bridge rectifier made up of multiple bridge-connected diodes, and the so-called totem-pole PFC is a PFC that includes a pair of switching elements of the same conductivity type that are connected in series in the same direction (totem-pole connection).

[0039] The receiving power conversion unit 16 includes, for example, a third bridge circuit formed by a plurality of switching elements and rectifying elements bridge-connected in two phases, and a voltage smoothing capacitor. Each switching element is, for example, a transistor such as a SiC MOSFET. The plurality of switching elements are high-side arm and low-side arm transistors 16a, 16b that form a pair in each phase. The rectifying element is, for example, a freewheeling diode connected in parallel to each of the transistors 16a, 16b. A voltage smoothing capacitor 16c is connected in parallel to the third bridge circuit.

[0040] For example, a power receiving device 4 equipped with a power receiving unit 15 and a power receiving power conversion unit 16 receives power transmitted from the power transmitting device 2 by controlling the on (conduction) and off (cutoff) switching of each switching element of the power receiving power conversion unit 16 in accordance with information on the frequency of power transmission by the power transmitting device 2.

[0041] The control device 17 comprehensively controls, for example, the drive control device 3, the power receiving device 4, and the in-vehicle communication device 18 of a mobile body such as a vehicle. The control device 17 is a software function unit that functions when a predetermined program is executed by a processor such as a CPU (Central Processing Unit). The software function unit is an ECU that includes a processor such as a CPU, a ROM (Read Only Memory) that stores programs, a RAM (Random Access Memory) that temporarily stores data, and electronic circuits such as a timer. At least a part of the control device 17 may be an integrated circuit such as an LSI (Large Scale Integration).

[0042] The control device 17 generates, for example, control signals indicating the timing for driving each switching element on (conducting) and off (blocking), and also generates gate signals for actually driving each switching element on and off based on the control signals. For example, the control device 17 controls the switching of each switching element of the power receiving device 4 to rectify the AC power received from the power transmitting device 2 into DC power, while improving the power factor of the input voltage and input current.

[0043] For example, the control device 17 controls the output according to the target output by a synchronous rectification operation that synchronously drives a plurality of switching elements of the power receiving device 4 to turn on and off, and a short-circuit operation that short-circuits the secondary coil 15a. For example, the control device 17 controls the synchronous rectification operation in accordance with the magnitude and phase of a current generated in the power receiving unit 15 by the power transmitted from the power transmitting device 2, i.e., a current Ir flowing through the secondary coil 15a. The control device 17 controls the multiple switching elements of the receiving power conversion unit 16 by soft switching of so-called zero voltage switching (ZVS). In zero voltage switching (ZVS), each switching element is turned on (switched from an off state to an on state) after the voltage across both ends of the switching element is made zero by discharging the output capacitance (parasitic capacitance) in the off state during the dead time period of each phase. For example, the control device 17 controls the short-circuit operation by turning on only the low-side arm of each phase while continuing the synchronous rectification operation of zero voltage switching (ZVS) in the high-side arm of each phase of the receiving power conversion unit 16.

[0044] For example, the control device 17 sets a communication section for communication and a power transmission section for power transmission in a coupling section near the power transmitting device 2 where the degree of coupling between the primary side coil 8a of the power transmitting device 2 and the secondary side coil 15a of the power receiving device 4 is equal to or greater than a predetermined level. For example, when the control device 17 receives key information through communication between the roadside communication device Ma and the in-vehicle communication device 18 before arriving at the coupling section, the control device 17 sends information about power transmission in the power transmission section from the power receiving device 4 to the power transmitting device 2 in the communication section before the power transmitting device 2 starts transmitting power in the power transmission section. Fig. 4 is a diagram showing an example of a correspondence relationship between the amount of relative movement between the primary coil 8a of the power transmitting device 2 and the secondary coil 15a of the power receiving device 4 and the output of power transmission at each voltage V1, V2, V3 in the embodiment. Fig. 5 is a diagram showing an example of a correspondence relationship between the amount of relative movement between the primary coil 8a of the power transmitting device 2 and the secondary coil 15a of the power receiving device 4 and the efficiency of power transmission in the embodiment. Fig. 6 is a diagram showing an example of communication and power transmission operations accompanying movement of a moving body (e.g., vehicle V) in the embodiment.

[0045] As shown in Figures 4 and 5, as the relative movement between the primary coil 8a and the secondary coil 15a increases from zero, the output and efficiency of power transmission tend to decrease. A state in which the movement is zero refers, for example, to a state in which the central axes of the primary coil 8a and the secondary coil 15a are aligned. The control device 17 defines a coupling section in which the degree of coupling between the primary coil 8a and the secondary coil 15a is equal to or greater than a predetermined value as a section in which the efficiency of power transmission is equal to or greater than a predetermined value (e.g., zero). The control device 17 defines a section in the coupling section in which the efficiency of power transmission is equal to or greater than a first predetermined value Ea (e.g., 80%) and the amount of relative movement between the primary coil 8a and the secondary coil 15a is equal to or less than a first movement Xa corresponding to the first predetermined value Ea as a power transmission section TS in which the degree of coupling between the primary coil 8a and the secondary coil 15a is relatively high. The control device 17 determines, in the coupling section, a section in which the efficiency of power transmission is less than a first predetermined value Ea and greater than a second predetermined value Eb (e.g., 0%), and the relative movement amount between the primary coil 8a and the secondary coil 15a is greater than the first movement amount Xa and less than a second movement amount Xb corresponding to the second predetermined value Eb, as a communication section CS in which the degree of coupling between the primary coil 8a and the secondary coil 15a is relatively small.

[0046] For example, when the primary coil 8a is present in the first communication section CS of the coupling section, the control device 17 sends information regarding power transmission in the power transmission section TS from the power receiving device 4 to the power transmitting device 2 through communication between the power transmitting device 2 and the power receiving device 4. 6, when the control device 17 sets a first communication section CS1 and a second communication section CS2 before and after a power transmission section TS along the moving direction of a moving body (e.g., a vehicle V), the control device 17 transmits information related to power transmission in the first communication section CS1, which is the first communication section CS, from the power receiving device 4 to the power transmitting device 2. The information related to power transmission includes, for example, key information acquired from the roadside communication device Ma, a required frequency for power transmission, a target output (power consumption) for fail-safe purposes, and information related to various abnormalities. The required frequency of power transmission is set so as to suppress a decrease in the efficiency of power transmission and output (power) based on, for example, the minimum ground clearance of the mobile body, which is related to the distance between the primary coil 8a and the secondary coil 15a, and the mounting layout of the power receiving device 4 on the mobile body. The control device 17 may set the required frequency depending on the state of power transmission between the power transmitting device 2 and the power receiving device 4. In addition, the control device 17 may, for example, when the primary side coil 8a is present in the last communication section CS of the coupling section (for example, the second communication section CS2 shown in Figure 6), send information indicating the stop of power transmission in the power transmission section TS and communication in the communication section CS from the power receiving device 4 to the power transmitting device 2 through communication between the power transmitting device 2 and the power receiving device 4.

[0047] For example, when the control device 17 receives key information through communication between the roadside communication device Ma and the in-vehicle communication device 18, it transmits information by transmitting power from the power receiving device 4 to the power transmitting device 2 in a reception standby state as a so-called ping signal in the communication section CS of the coupling section. The power receiving device 4 communicates using a voltage induced in the primary coil 8a of the power transmitting device 2 by a magnetic field generated in the secondary coil 15a by a current switching operation performed by switching in the receiving power conversion unit 16. The control device 17 executes the ping transmission by, for example, switching a carrier wave for contactlessly transmitting power from the power receiving device 4 to the power transmitting device 2 at a predetermined duty ratio to generate a two-level digital signal, so-called dominant and recessive. The predetermined duty ratio is, for example, a predetermined minimum to approximately 50%. Note that the control device 17 may transmit information by, for example, amplitude modulating the carrier wave by changing the switching duty ratio.

[0048] The control device 17 transmits a PING signal at a predetermined interval, for example, from several tens of microseconds to several milliseconds, and when it receives a response signal to the PING signal from the power transmitting device 2, it starts power reception control for the power transmission from the power transmitting device 2 in the power transmission section TS. The control device 17 sets the timing of PING transmission according to, for example, information about the installation of the power transmission device 2 received from the roadside communication device Ma and the moving state of the moving body (e.g., vehicle V) (i.e., the moving state of the power receiving device 4) so ​​that communication (i.e., mutual transmission and reception) between the power transmission device 2 and the power receiving device 4 in the communication section CS is properly completed. For example, the control device 17 sets the transmission period according to information such as the installation intervals of the multiple power transmission units 8 and the speed of the moving body (e.g., the speed of the vehicle V) so that PING transmission is completed at least a predetermined number of times (e.g., once) in the communication section CS. Note that, for example, even if the control device 17 permits the execution of PING transmission in the communication section CS, it transitions to a standby state in which the execution of PING transmission is stopped outside the communication section CS. For example, in the standby state for PING transmission, the control device 17 may start the execution of PING transmission immediately before the mobile object reaches the first communication section CS of the next connection section as the mobile object moves.

[0049] Hereinafter, as the operation of the contactless power transfer system 1, the processes executed by the power transmission side control device 9 and the control device 17 will be described. FIG. 7 is a flowchart showing the power receiving side process executed by the control device 17 of the contactless power transfer system 1 in the embodiment. 7, the control device 17 determines whether electronic payment for power transmission from the power transmitting device 2 to the mobile object is possible through wireless communication (billing communication) between the roadside communication device Ma and the in-vehicle communication device 18. If the determination result is "NO," the control device 17 repeats the processing of step S01. On the other hand, if the determination result is "YES," the control device 17 proceeds to step S02.

[0050] Then, in step S02, the control device 17 acquires key information required to start power transmission from the roadside communication device Ma. Next, in step S03, the control device 17 generates a signal for PING transmission by power transmission from the power receiving device 4 to the power transmitting device 2. Next, in step S04, the control device 17 executes PING transmission at a predetermined cycle in the first communication section CS of the coupling section. Next, in step S05, the control device 17 determines whether or not a response signal to the PING transmission has been received from the power transmitting device 2. If the result of this determination is "NO", the control device 17 repeats the process of step S05. On the other hand, if the result of this determination is "YES", the control device 17 proceeds to step S06. Then, in step S06, the control device 17 starts power reception control for the power transmission from the power transmission device 2 in the power transmission section TS. Then, the control device 17 advances the process to the end.

[0051] FIG. 8 is a flowchart showing the power transmission side process executed by the power transmission side control device 9 of the contactless power transmission system 1 in the embodiment. 8, the power transmitting side control device 9 determines whether or not key information has been transmitted from the roadside communication device Ma to the power receiving device 4. If the determination result is "NO", the power transmitting side control device 9 proceeds to step S12. On the other hand, if the determination result is "YES", the power transmitting side control device 9 proceeds to step S13. Then, in step S12, the power transmitting side control device 9 maintains the stopped state of the power transmitting device 2, and returns the process to step S11. Then, in step S13, the power transmitting side control device 9 causes the power transmitting device 2 to transition from the stopped state to the reception standby state.

[0052] Next, in step S14, the power transmitting side control device 9 determines whether or not a PING signal due to power transmission from the power receiving device 4 to the power transmitting device 2 has been received in the first communication section CS of the coupling section. If the determination result is "NO", the power transmitting side control device 9 repeats the process of step S14. On the other hand, if the determination result is "YES", the power transmitting side control device 9 proceeds to step S15. Next, in step S15, the power transmitting side control device 9 collates the key information received from the communication control device Mb with the key information received from the power receiving device 4.

[0053] Next, in step S16, the power transmitting side control device 9 determines whether the key information received from the communication control device Mb matches the key information received from the power receiving device 4. If the result of this determination is "NO", the power transmitting side control device 9 proceeds to end the process. On the other hand, if the result of this determination is "YES", the power transmitting side control device 9 proceeds to step S17. Next, in step S17, the power transmitting side control device 9 transmits a response signal to the PING transmission to the power receiving device 4 by transmitting power from the power transmitting device 2 to the power receiving device 4 in the communication section CS. Next, in step S18, the power transmitting side control device 9 starts power transmission control in the power transmission section TS for power transmission to the power receiving device 4 at the requested frequency received from the power receiving device 4. Then, the control device 17 advances the process to END.

[0054] As described above, the contactless power transfer system 1 of the embodiment is provided with the control device 17 that sends information about power transfer from the power receiving device 4 to the power transmitting device 2 in the communication section CS prior to reaching the power transfer section TS, thereby ensuring the desired power and transfer efficiency. For example, even if the speed of a mobile object carrying the power receiving device 4 is high and the time it takes to pass through the power transfer section TS is short, the control device 17 can quickly start power transfer in the power transfer section TS by sending information about power transfer before reaching the power transfer section TS. The control device 17 sets the timing of communication in the communication section CS (e.g., period and number of times, etc.) according to the moving state of the mobile body equipped with the power receiving device 4, such as its speed, so that communication can be completed properly in the communication section CS and an increase in power consumption can be suppressed by preventing excessive communication from being performed.

[0055] The desired power and transmission efficiency can be ensured by providing a control device 17 that sends information about the required frequency for power transmission to the power transmitting device 2. For example, even if the coupling coefficient decreases due to the vehicle's minimum ground clearance and the mounting layout of the power receiving device 4, which are related to the distance between the primary coil 8a of the power transmitting device 2 and the secondary coil 15a of the power receiving device 4, the decrease in transmission power and transmission efficiency can be suppressed by using a required frequency that offsets the fluctuation in mutual inductance.

[0056] By providing the control device 17 and the transmitting-side control device 9 that transition the power transmitting device 2 to a reception standby state before reaching the coupling section, it is possible to quickly receive and verify the key information in the communication section CS. Since the power transmitting device 2 is in a stopped state before the control device 17 acquires the key information, an increase in standby power consumption can be suppressed. The reception standby state of the power transmitting device 2 is a state in which the primary coil 8a is short-circuited by the power transmitting power conversion unit 7, so that communication of information from the power receiving device 4 to the power transmitting device 2 via a magnetic field can be easily detected by the voltage induced in the primary coil 8a.

[0057] (Variation) Modifications of the embodiment will be described below. Note that the same parts as those in the above-described embodiment will be denoted by the same reference numerals, and descriptions thereof will be omitted or simplified. In the above-described embodiment, the control device 17 sets the transmission period so that at least one PING transmission is completed in the communication section CS, but this is not limiting. For example, the control device 17 may set the transmission period according to information such as the installation intervals of the multiple power transmission units 8 and the speed of the moving body (e.g., the speed of the vehicle V) so that the number of PING transmissions completed is equal to or less than a predetermined upper limit. The control device 17 can suppress an increase in power consumption by restricting the number of PING transmissions in the communication section CS.

[0058] In the above-described embodiment, the communication system M constitutes an electronic toll collection system, but is not limited to this. For example, the communication system M may simply be a system that communicates with the in-vehicle communication device 18 prior to communication and power transmission in a predetermined coupling section.

[0059] In the above-described embodiment, the key information, the required frequency, and other information are transmitted and received by power transmission between the power transmitting device 2 and the power receiving device 4. However, this is not limiting. For example, the power transmitting device 2 and the power receiving device 4 may each include a communication device for wirelessly communicating with each other, and the key information, the required frequency, and other information may be transmitted and received via the communication device.

[0060] In the above-described embodiment, the contactless power transfer system 1 is provided with the storage voltage conversion unit 12 that converts the input and output power of the storage device 11, but this is not limited to this, and the storage voltage conversion unit 12 may be omitted. For example, in the case of a hybrid vehicle that is powered by a power storage device 11 and an internal combustion engine, the drive control device 3 is provided with a power storage voltage conversion unit 12, while in the case of an electric vehicle that is powered by a power storage device 11, the drive control device 3 does not need to be provided with a power storage voltage conversion unit 12.

[0061] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0062] 1...contactless power transfer system, 2...power transfer device, 3...drive control device, 4...power receiving device, 6...power supply unit, 7...transmission power conversion unit, 8...power transfer unit, 8a...primary side coil (power transfer side coil), 9...power transfer side control device, 11...power storage device, 12...storage voltage conversion unit, 13...power conversion unit, 14...rotating electric machine, 15...power receiving unit, 15a...secondary side coil (power receiving side coil), 16...receiving power conversion unit (power conversion unit), 17...control device, 18...on-board communication device, CS...communication section, CS1...first communication section, CS2...second communication section, TS...power transfer section, M...communication system, Ma...roadside communication device (communication device), Mb...communication control device.

Claims

1. a power receiving device having a power receiving side coil that receives and transmits power transmitted in a non-contact manner between the power receiving device and a power transmitting side coil of the power transmitting device; a control device that controls the power receiving device; Equipped with The control device In a coupling section in which the degree of coupling between the power transmitting side coil and the power receiving side coil is equal to or greater than a predetermined value, a communication section in which the degree of coupling is relatively small and a power transmission section in which the degree of coupling is relatively large are set, When the power receiving side coil is present in the first communication section of the coupling section, information regarding power transmission in the power transmission section is sent from the power receiving device to the power transmitting device through communication between the power transmitting device and the power receiving device; The information regarding the power transmission is set to include at least key information and information regarding a required frequency of the power transmission. Contactless power transmission system.

2. The control device The timing of communication between the power transmitting device and the power receiving device in the communication section is set according to a movement state of the power receiving side coil. The contactless power transfer system according to claim 1 .

3. The control device The information regarding the power transmission is sent from the power receiving device to the power transmitting device in the first communication section, causing the power transmitting device to execute the power transmission at the requested frequency in accordance with the collation of the key information in the power transmission section. The contactless power transfer system according to claim 1 or 2.

4. a communication device whose communication with an externally placed communication device is controlled by the control device; The control device The key information is acquired through communication between the communication device and the communication apparatus before the power receiving side coil reaches the coupling section, thereby causing the power transmitting apparatus to transition from a stopped state to a standby state for receiving the information regarding the power transmission, and maintaining the standby state for receiving the information until the matching of the key information is completed. The contactless power transfer system according to claim 3 .

5. The control device The reception standby state is a short-circuit state of the power transmitting side coil, In the communication between the power transmitting device and the power receiving device, Communication is performed using a voltage induced in the power transmission side coil by a magnetic field generated in the power reception side coil during a power supply switching operation of the power reception device. The contactless power transfer system according to claim 4 .

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