JP2020115703A - Non-contact power transmission system - Google Patents

Abstract

To suppress a turn-on current of an inverter in a non-contact power transmission device by circuit control in a non-contact power receiving device.SOLUTION: A vehicle 2 includes an LC resonance circuit R2, a rectifier circuit 206 that converts AC power received contactlessly by the LC resonance circuit R2 into DC power, a filter circuit F2 configured to change the power receiving inductance between the LC resonance circuit R2 and the rectifier circuit 206, a vehicle ECU 500 that controls a variable inductor 204 included in the filter circuit F2, and a communication device 600 that receives, from the power transmission unit 100, inverter information indicating the magnitude of the turn-on current of the inverter 120 included in the power transmission unit 100. The vehicle ECU 500 is configured such that the larger the turn-ON current indicated by the inverter information, the smaller the power receiving inductance by the variable inductor 204.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a contactless power transmission system.

A contactless power transfer system is known that transfers power from a power transmission coil of a contactless power transmission device to a power reception coil of a contactless power reception device in a contactless manner. For example, a contactless power transmission system described in Japanese Unexamined Patent Application Publication No. 2016-111903 (Patent Document 1) includes, in addition to a power transmitting coil, a power receiving coil, and a control unit, an inverter that converts DC power into AC power. It further comprises a filter that supplies the power transmission coil with power in which the high frequency of the output power of the inverter is reduced. The inverter and the filter are mounted on the non-contact power transmission device. The inverter includes a plurality of switching elements and a plurality of diodes, and is driven by PWM (Pulse Width Modulation) control. The filter includes a variable inductor. Then, the control means estimates the coupling coefficient between the power transmitting coil and the power receiving coil, and controls the variable inductor so that the inductance of the filter increases as the coupling coefficient increases.

JP, 2016-111903, A

In the non-contact power transmission system described in Patent Document 1, the non-contact power transmission device is installed in a parking lot, and the non-contact power reception device is mounted in an electric vehicle. BACKGROUND ART In recent years, electric vehicles have been rapidly spread from the viewpoint of environmental protection, etc., and the speed of development of vehicle models of electric vehicles has increased. Various vehicle models of electric vehicles have been developed, and it is difficult for the non-contact power transmission device to support all vehicle models. In the non-contact power transmission device, the turn-on current of the inverter cannot be sufficiently suppressed only by changing the inductance of the filter, and switching loss of the inverter may increase. The turn-on current is the output current of the inverter when the output voltage of the inverter rises.

The present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a non-contact power transmission device when non-contact power is transmitted from the non-contact power transmission device to the non-contact power reception device in the non-contact power transmission system. It is to suppress the turn-on current of the inverter in 1 above by the circuit control in the non-contact power receiving device.

A contactless power transmission system according to a first aspect of the present disclosure is configured to contactlessly transfer power from a power transmission unit of a contactless power transmission device to a power reception unit of a contactless power reception device. The non-contact power transmission device includes a power transmission circuit that constitutes the power transmission unit, an inverter that converts DC power into AC power and outputs the AC power to a power transmission circuit, a turn-ON current (that is, an output of the inverter when the output voltage of the inverter rises). A first communication device that transmits inverter information indicating the magnitude of the electric current) to the non-contact power receiving device. The non-contact power receiving device includes a power receiving circuit that constitutes the power receiving unit, a rectifying circuit that converts AC power received by the power receiving circuit in a non-contact manner into DC power, and an inductance between the power receiving circuit and the rectifying circuit (hereinafter, An "inductance adjusting circuit" is also configured to be changeable, a control device that controls the inductance adjusting circuit, and a second communication device that receives inverter information from the non-contact power transmitting device. The control device is configured such that the larger the turn-ON current indicated by the inverter information, the smaller the power receiving inductance by the inductance adjusting circuit.

In the non-contact power transmission device, a phase difference (hereinafter, referred to as “INV current phase”) between a phase of an inverter output voltage (hereinafter also referred to as “INV voltage phase”) and a phase of an inverter output current (hereinafter also referred to as “INV current phase”). It is considered that the output power factor (ratio of active power to apparent power) of the inverter becomes 1 and the turn-on current becomes 0 when there is no "INV phase difference"). When performing non-contact power transmission from the power transmission unit of the non-contact power transmission device to the power reception unit of the non-contact power reception device, the power transmission unit and the power reception unit are not properly aligned and the position shifts ) Occurs, the distance between the power transmission unit and the power reception unit becomes long, and the INV current phase tends to shift to the advance side with respect to the INV voltage phase. It is considered that the INV current phase deviates from the INV voltage phase toward the advance side as the turn-ON current increases. On the other hand, the smaller the power receiving inductance is, the more the INV current phase tends to be retarded with respect to the INV voltage phase. Therefore, the INV phase difference can be reduced by reducing the power receiving inductance as the turn-ON current increases. As the INV phase difference decreases, the turn-ON current also decreases. As described above, the non-contact power receiving device, when receiving power from the non-contact power transmitting device in a non-contact manner, controls the inductance adjusting circuit to adjust the power receiving inductance to turn the inverter of the non-contact power transmitting device. The ON current can be suppressed.

The above control device determines whether or not the turn-on current exceeds a predetermined threshold value, and the power receiving inductance when the turn-on current exceeds the threshold value is calculated from the power receiving inductance when the turn-on current does not exceed the threshold value. May be configured to be small. Further, the above control device may be configured to use a plurality of thresholds for determining the magnitude of the turn-ON current and switch the power receiving inductance in multiple stages according to the magnitude of the turn-ON current. .. Further, the above control device may be configured to continuously adjust the power receiving inductance so that the power receiving inductance follows the change of the turn-ON current in real time.

A non-contact power receiving device according to a second aspect of the present disclosure is configured to receive power transmitted from a power transmitting unit of the non-contact power transmitting device in a non-contact manner by the power receiving unit. This non-contact power receiving device includes a power receiving circuit that constitutes the power receiving unit, a rectifying circuit that converts AC power received by the power receiving circuit in a non-contact manner into DC power, and an inductance (power receiving circuit) between the power receiving circuit and the rectifying circuit. (Inductance) changeable inductance control circuit, a control device for controlling the inductance adjustment circuit, and inverter information indicating the magnitude of the turn-on current of the inverter included in the non-contact power transmission device are received from the non-contact power transmission device. And a communication device. The control device is configured such that the larger the turn-ON current indicated by the inverter information, the smaller the power receiving inductance by the inductance adjusting circuit.

Such a non-contact power receiving device suppresses the turn-on current of the inverter in the non-contact power transmitting device by controlling the inductance adjusting circuit to adjust the power receiving inductance when the power is received from the non-contact power transmitting device in a non-contact manner. be able to.

The communication device in the non-contact power receiving device may be configured to request the non-contact power transmitting device to transmit the inverter information and receive the inverter information transmitted from the non-contact power transmitting device in response to the request. Good.

According to the present disclosure, when power is transmitted from a non-contact power transmission device to a non-contact power receiving device in a non-contact power transmission system in a non-contact manner, a turn-on current of an inverter in the non-contact power transmitting device is controlled by a circuit in the non-contact power receiving device. Can be suppressed by.

1 is an overall configuration diagram of a contactless power transmission system according to an embodiment of the present disclosure. It is a figure which shows the structure for performing non-contact electric power transmission between a charging installation and a vehicle in the non-contact electric power transmission system shown in FIG. FIG. 3 is a diagram showing an example of a circuit configuration of the inverter shown in FIG. 2. It is a figure which shows the switching waveform of the inverter shown in FIG. 2, and each waveform of output voltage V _inv and output current I _inv . It is a diagram for illustrating receiving inductance control by the control device (L ₂₁ Control) of the non-contact power transmitting device. It is a figure which shows the output voltage waveform and output current waveform of an inverter when the INV current phase has shifted|deviated to the advance side with respect to the INV voltage phase. It is a figure which shows the output voltage waveform and output current waveform of an inverter when INV phase difference (phi) is 0. Magnitude of the coupling coefficient is a diagram illustrating the relationship between the INV phase difference φ and the power receiving inductor L ₂₁ in three different situations. It is a diagram showing the relationship between the power receiving inductor L ₂₁ and the turn ON current when the coupling coefficient is small. 3 is a flowchart showing a processing procedure of charging control executed by a vehicle control device in the power transmission system shown in FIG. 1. 3 is a flowchart showing a processing procedure of power transmission control executed by a control device of charging equipment in the power transmission system shown in FIG. 1. 12 is a flowchart showing a processing procedure of duty control shown in FIG. 11. It is a figure which shows the modification of the circuit structure of an electric power transmission system. It is a figure which shows the 1st modification of an inductance adjustment circuit. It is a figure which shows the 2nd modification of an inductance adjustment circuit.

Embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and description thereof will not be repeated.

Arrows F, B, U, and D in the drawings used below indicate directions with respect to the vehicle. Arrow F is "forward", arrow B is "rear", arrow U is "up", arrow D indicates "bottom". In the following, the electronic control unit will be referred to as "ECU (Electronic Control Unit)".

FIG. 1 is an overall configuration diagram of a contactless power transmission system according to an embodiment of the present disclosure. Referring to FIG. 1, a contactless power transmission system (hereinafter, also simply referred to as “power transmission system”) 10 includes a charging facility 1 (ground equipment) and a vehicle 2.

The charging facility 1 includes a power transmission unit 100 and an AC power supply 700 that supplies power to the power transmission unit 100. Power transmission unit 100 is installed on ground F10 (for example, the floor surface of a parking lot). An example of the AC power supply 700 is a household power supply (for example, an AC power supply having a voltage of 200 V and a frequency of 50 Hz). In this embodiment, the power transmission unit 100 corresponds to an example of a “contactless power transmission device” according to the present disclosure.

Vehicle 2 includes power reception unit 200, power storage device 300 charged by the power received by power reception unit 200, and vehicle ECU 500 controlling the power received by power reception unit 200. Power reception unit 200 is provided on the lower surface (road surface side) of power storage device 300 installed on lower surface F20 (underfloor) of vehicle 2. In this embodiment, the vehicle 2 constitutes an example of the “non-contact power receiving device” according to the present disclosure.

The vehicle 2 may be an electric vehicle that can travel using only the electric power stored in the power storage device 300, or may use both the electric power stored in the power storage device 300 and the output of the engine (not shown). It may be a hybrid vehicle that can travel.

The power transmission unit 100 is configured to transmit power to the power reception unit 200 through a magnetic field in a contactless manner in a state in which the vehicle 2 is aligned such that the power reception unit 200 of the vehicle 2 faces the power transmission unit 100. The power reception unit 200 receives the power from the power transmission unit 100 in a contactless manner.

Hereinafter, the height from the wheel installation surface of the vehicle 2 (that is, the ground F10) to the power receiving coil of the power receiving unit 200 is referred to as “power receiving coil height ΔH”. In this embodiment, the power receiving coil height ΔH of the vehicle 2 matches the minimum ground clearance of the vehicle 2. The distance between the power transmission coil provided on the surface of power transmission unit 100 and the power reception coil provided on the surface of power reception unit 200 varies depending on the height ΔH of the power reception coil.

The power transmitting coil and the power receiving coil are the primary coil 101 and the secondary coil 201 shown in FIG. 2, respectively. FIG. 2 is a diagram showing a configuration for performing non-contact power transmission between charging facility 1 and vehicle 2. The power transmission unit 100 and the power reception unit 200 shown in FIG. 1 have a configuration as shown in FIG.

Referring to FIG. 2, power transmission unit 100 obtains power for transmission by performing a predetermined power conversion process on the power received from AC power supply 700, and transmits the power for transmission to power reception unit 200 in a contactless manner. Is composed of. Then, the power storage device 300 (vehicle-mounted battery) is charged by the electric power received by the power receiving unit 200 from the power transmitting unit 100.

Power transmission unit 100 includes a power conversion unit that performs the power conversion process, an LC resonance circuit R1 that performs the non-contact power transmission, and a power transmission ECU 150 that controls the power conversion unit and the like. The power conversion unit includes an AC/DC converter 130, an inverter 120, and a filter circuit F1. The LC resonance circuit R1 is provided on the output side of the inverter 120, and is configured by connecting the primary coil 101 and the capacitor 102 in series. The LC resonance circuit R1 according to this embodiment corresponds to an example of a “power transmission circuit” according to the present disclosure.

AC/DC converter 130 rectifies and transforms the electric power received from AC power supply 700 and outputs it to inverter 120. AC/DC converter 130 is configured to include, for example, a rectifier circuit including a diode, and a boost DC/DC converter including a switching element chopper-controlled by power transmission ECU 150 (for example, a power semiconductor switching element). AC/DC converter 130 boosts the electric power received from AC power supply 700 to 400 V, and outputs DC power of voltage 400 V to inverter 120, for example.

The inverter 120 is configured to convert input power (more specifically, DC power) from the AC/DC converter 130 into AC power having a predetermined magnitude and frequency and output the AC power to the LC resonance circuit R1. The output power of the inverter 120 is supplied to the LC resonance circuit R1 through the filter circuit F1. In this embodiment, the inverter 120 is a voltage source inverter (for example, a single-phase full bridge circuit shown in FIG. 3 described later). The inverter 120 is configured to be able to change the frequency of output power (hereinafter, also simply referred to as “output frequency”) within a predetermined frequency range. Each switching element forming the inverter 120 is controlled according to a drive signal from the power transmission ECU 150.

The output frequency of the inverter 120 changes according to the switching frequency indicated by the drive signal (hereinafter, also referred to as “drive frequency”). In this embodiment, the drive frequency of the inverter 120 matches the output frequency of the inverter 120, and thus the power transmission frequency (frequency of transmitted power).

Further, as will be described in detail later, the duty of the output voltage of the inverter 120 is also controlled according to the drive signal from the power transmission ECU 150. Then, the magnitude of the output power of the inverter 120 changes according to the duty of the output voltage of the inverter 120. The duty of the output voltage of the inverter 120 is defined as the ratio of the positive (or negative) voltage output time to the cycle of the output voltage waveform (rectangular wave) (see FIG. 4 described later).

The filter circuit F1 includes a capacitor 103 and a coil 104. The capacitor 103 is connected in parallel with the LC resonance circuit R1, and the coil 104 is connected in series with the LC resonance circuit R1. The capacitor 103 and the coil 104 form an LC filter that functions as a low-pass filter. Electromagnetic noise is reduced by this LC filter.

The LC resonance circuit R1 transmits power to the LC resonance circuit R2 of the power receiving unit 200 in a non-contact manner through the magnetic field generated around the primary coil 101. The LC resonance circuit R1 is a series resonance circuit. The Q value of the LC resonance circuit R1 is preferably 100 or more.

The power transmission ECU 150 includes an arithmetic device, a storage device, an input/output port, a communication port (all not shown), and the like. The arithmetic unit is composed of, for example, a microprocessor including a CPU (Central Processing Unit). The storage device includes a RAM (Random Access Memory) that temporarily stores data, and a storage (ROM (Read Only Memory), a rewritable nonvolatile memory, or the like) that stores programs and the like. Various controls are executed by the arithmetic unit executing the program stored in the storage device. For example, power transmission ECU 150 controls switching elements included in inverter 120 and AC/DC converter 130 to adjust power transmission. The various controls are not limited to the processing by software, but may be processed by dedicated hardware (electronic circuit).

The power transmission unit 100 further includes a voltage sensor 181 and current sensors 182 to 184. Voltage sensor 181 detects the input voltage of inverter 120 and outputs the detected value to power transmission ECU 150. Current sensor 182 detects the input current of inverter 120 and outputs the detected value to power transmission ECU 150. Current sensor 183 detects the output current of inverter 120 and outputs the detected value to power transmission ECU 150. Current sensor 184 detects the output current of filter circuit F1 (that is, the current processed by filter circuit F1) and outputs the detected value to power transmission ECU 150. The power transmission unit 100 may further include a temperature sensor (not shown) for detecting an abnormality.

In this embodiment, the input voltage of inverter 120 and the output voltage of AC/DC converter 130 match. Further, the input current of the inverter 120 and the output current of the AC/DC converter 130 also match. The output current of the filter circuit F1 matches the current flowing through the LC resonance circuit R1 (primary coil 101 etc.).

The power transmission unit 100 further includes a communication device 160. The communication device 160 is a communication interface for performing wireless communication with the vehicle 2. Communication device 160 sends information from power transmission ECU 150 to vehicle 2 or receives information from vehicle 2 and outputs it to power transmission ECU 150. The power transmission ECU 150 and the communication device 160 according to this embodiment constitute an example of a “first communication device” according to the present disclosure. The power transmission ECU 150 is configured to transmit the inverter information indicating the magnitude of the turn-on current of the inverter 120 to the vehicle 2 via the communication device 160.

The power receiving unit 200 includes an LC resonance circuit R2, a filter circuit F2, a rectifying circuit 206, and a smoothing capacitor 207. The LC resonance circuit R2 according to this embodiment corresponds to an example of the “power receiving circuit” according to the present disclosure.

The LC resonance circuit R2 is configured by connecting a secondary coil 201 and a capacitor 202 in series. Prior to the start of power transmission, the primary coil 101 and the secondary coil 201 are aligned so as to generate an interlinking magnetic flux. Then, electric power is sent from the primary coil 101 to the secondary coil 201 by magnetic resonance. The secondary coil 201 receives power from the primary coil 101 of the power transmission unit 100 in a non-contact manner. The Q value of the LC resonance circuit R2 is preferably 100 or more. In this embodiment, as the LC resonance circuits R1 and R2, SS type (primary side: series, secondary side: series) resonance circuits are adopted, but the present invention is not limited to this, and SP type (primary side: series). , Secondary side: parallel), PP method (primary side: parallel, secondary side: parallel), etc. may be adopted.

As described above, in this embodiment, the LC resonance circuit R2 is a series resonance circuit. Hereinafter, the terminal of the LC resonance circuit R2 on the side of the secondary coil 201 is referred to as "L terminal", and the terminal of the LC resonance circuit R2 on the side of capacitor 202 is referred to as "C terminal". Further, an electric wire connecting the L terminal of the LC resonance circuit R2 and the terminal T5 of the rectification circuit 206 is called "power line PL1", and an electric wire connecting the C terminal of the LC resonance circuit R2 and the terminal T6 of the rectification circuit 206 is called "power line PL2". To call.

The filter circuit F2 includes capacitors 203 and 205 and a variable inductor 204. An LC filter that functions as a low-pass filter (more specifically, a π-type LC filter) is formed by the capacitors 203 and 205 and the variable inductor 204. The LC filter reduces the electromagnetic noise generated when the power is received. The filter circuit F2 according to this embodiment corresponds to an example of an “inductance adjusting circuit” according to the present disclosure.

The variable inductor 204 is provided on the power line PL2. That is, the variable inductor 204 is connected in series with the LC resonance circuit R2. The variable inductor 204 includes, for example, a magnetic body (core) and an excitation winding, and is configured such that the inductance continuously changes according to a control signal from the power transmission ECU 150 (more specifically, the current of the excitation winding). To be done. The inductance of the variable inductor 204 (hereinafter, also referred to as “power receiving inductance L ₂₁ ”, or simply “L ₂₁ ”) can be adjusted to an arbitrary value by causing a DC superimposed current to flow in the excitation winding to change the magnetic permeability. The variable inductor is not limited to this variable inductor, and an arbitrary variable inductor can be selected and used from various known variable inductors.

The capacitor 203 is connected in parallel to the LC resonance circuit R2 on the LC resonance circuit R2 side of the variable inductor 204. One end of the capacitor 203 is connected to the power line PL1 and the other end of the capacitor 203 is connected to the power line PL2.

The capacitor 205 is connected in parallel to the LC resonance circuit R2 on the rectifier circuit 206 side of the variable inductor 204. One end of the capacitor 205 is connected to the power line PL1, and the other end of the capacitor 205 is connected to the power line PL2.

Rectifier circuit 206 rectifies the AC power received by secondary coil 201 and outputs it to power storage device 300. A known rectifier circuit can be used as the rectifier circuit 206. In this embodiment, a voltage doubler rectifier circuit is used as the rectifier circuit 206. The rectifier circuit 206 (double voltage rectifier circuit) is configured by connecting two capacitors Cb1 and Cb2 to the output side of a bridge circuit D10 composed of four diodes. Each diode that constitutes the bridge circuit D10 contributes to rectification, and the capacitors Cb1 and Cb2 connected in parallel to the diode contribute to boosting. A smoothing capacitor 207 is provided on the output side of the rectifier circuit 206. The capacitor 207 smoothes the DC power rectified by the rectifier circuit 206. With the rectifier circuit 206 and the capacitor 207, stable power can be supplied to the power storage device 300 even if the voltage of the power storage device 300 changes.

The power receiving unit 200 further includes current sensors 283 and 284. Current sensor 284 detects a current flowing through LC resonance circuit R2 (secondary coil 201 and the like) and outputs the detected value to power transmission ECU 150. Current sensor 283 detects a current of filter circuit F2 (more specifically, a current flowing between capacitors 203 and 205 in power line PL1) and outputs the detected value to power transmission ECU 150. The power receiving unit 200 may further include a temperature sensor (not shown) for detecting an abnormality.

Output power of power receiving unit 200 (that is, DC power smoothed by capacitor 207) is supplied to power storage device 300 via charging relay 400. The charging relay 400 is ON/OFF controlled by the vehicle ECU 500, and is turned ON (conduction state) when the power storage unit 200 charges the power storage device 300.

Power storage device 300 is a rechargeable DC power supply. Power storage device 300 is configured to include, for example, a secondary battery (lithium ion battery, nickel hydrogen battery, or the like). Power storage device 300 stores the electric power supplied from power receiving unit 200 and supplies the electric power to a vehicle drive device (not shown) (for example, a traveling motor and its drive circuit).

For power storage device 300, a monitoring unit 310 that monitors the state of power storage device 300 is provided. Monitoring unit 310 includes various sensors that detect the state (temperature, current, voltage, etc.) of power storage device 300, and outputs the detection result to vehicle ECU 500. Vehicle ECU 500 is configured to acquire the state (SOC (State Of Charge) or the like) of power storage device 300 based on the output of monitoring unit 310. The SOC indicates the remaining charge amount, and represents, for example, the ratio of the current charge amount to the charge amount in the fully charged state, which is represented by 0 to 100%.

Vehicle ECU 500 includes an arithmetic device, a storage device, an input/output port, a communication port (all not shown), and the like, and controls various devices in vehicle 2. The arithmetic unit is constituted by a microprocessor including a CPU, for example. The storage device includes a RAM and a storage (ROM, rewritable nonvolatile memory, or the like) that stores programs and the like. In addition to the program, the storage device stores various kinds of information (for example, error information used in the process of FIG. 10 described later). Various controls are executed by the arithmetic unit executing the program stored in the storage device. Vehicle ECU 500 executes, for example, traveling control of vehicle 2 and charging control of power storage device 300. An ON/OFF signal or the like from vehicle ECU 500 to charging relay 400 is output from the output port. The various controls are not limited to the processing by software, but may be processed by dedicated hardware (electronic circuit). The vehicle ECU 500 according to this embodiment corresponds to an example of a “control device” according to the present disclosure. The vehicle ECU 500 is configured to control the filter circuit F2 (particularly, the variable inductor 204).

The vehicle 2 further includes a communication device 600. The communication device 600 is a communication interface for performing wireless communication with the power transmission unit 100. By performing wireless communication between the communication device 160 of the charging facility 1 and the communication device 600 of the vehicle 2, information can be exchanged between the power transmission ECU 150 and the vehicle ECU 500. The communication device 600 according to this embodiment corresponds to an example of a “second communication device” according to the present disclosure. The communication device 600 is configured to receive the inverter information from the power transmission unit 100.

FIG. 3 is a diagram showing an example of a circuit configuration of inverter 120 shown in FIG. Referring to FIG. 3, inverter 120 includes a plurality of switching elements Q1 to Q4 and a plurality of free wheeling diodes D1 to D4. The switching elements Q1 to Q4 are composed of, for example, power semiconductor switching elements (IGBT, bipolar transistor, MOSFET, GTO, or the like). The free wheeling diodes D1 to D4 are connected in parallel (more specifically, antiparallel) to the switching elements Q1 to Q4, respectively. The AC/DC converter 130 (FIG. 1) is connected to the DC side input terminals T1 and T2, and the filter circuit F1 (FIG. 1) is connected to the AC side output terminals T3 and T4.

The DC voltage output from the AC/DC converter 130 is applied between the input terminals T1 and T2. In FIG. 3, V1 indicates the magnitude of this DC voltage. Switching elements Q1 to Q4 are driven by a drive signal from power transmission ECU 150. Then, due to the switching operation of the switching elements Q1 to Q4, the output voltage V _inv is applied between the output terminals T3 and T4, and the output current I _inv flows (the direction indicated by the arrow in FIG. 3 is positive). In FIG. 3, as an example, a state in which the switching elements Q1 and Q4 are ON and the switching elements Q2 and Q3 are OFF is shown, and the output voltage V _{inv in} this case is approximately V1 (a positive value). Become.

FIG. 4 is a diagram showing a switching waveform of the inverter 120 and respective waveforms of the output voltage V _inv and the output current I _inv . Hereinafter, with reference to FIG. 4 together with FIG. 3, the operation of the inverter 120 will be described by taking one cycle from time t4 to t8 as an example.

At time t4, when the switching elements Q2 and Q4 are OFF and ON, respectively, and the switching element Q1 is switched from OFF to ON and the switching element Q3 is switched from ON to OFF, the respective switching elements are in the states shown in FIG. , The output voltage V _inv of the inverter 120 rises from 0 to V1 (a positive value).

After that, at times t5 to t8, the output voltage V _inv also changes as the state of each switching element changes as shown below. At time t5, when the switching element Q2 switches from OFF to ON and the switching element Q4 switches from ON to OFF, the output voltage V _inv becomes 0. At time t6, when the switching element Q1 switches from ON to OFF and the switching element Q3 switches from OFF to ON, the output voltage V _inv becomes −V1 (negative value). At time t7, when the switching element Q2 switches from ON to OFF and the switching element Q4 switches from OFF to ON, the output voltage V _inv becomes 0 again.

At time t8, which is one cycle after time t4, switching element Q1 switches from OFF to ON and switching element Q3 switches from ON to OFF. As a result, each switching element is in the same state as at time t4, and the output voltage _Vinv rises from 0 to V1 (a positive value).

FIG. 4 shows a case where the duty of the output voltage V _inv is 0.25. The ratio of the positive voltage output time (t4 to t5) in one cycle (t4 to t8) is ¼ (=0.25). The ratio of the negative voltage output time (t6 to t7) in one cycle (t4 to t8) is also ¼ (=0.25). As the duty of the output voltage _Vinv increases, the time during which the output voltage _Vinv is the positive voltage (V1) or the negative voltage (-V1) in one cycle becomes longer. Therefore, the larger the duty of the output voltage V _inv , the larger the output power of the inverter 120.

The duty of the output voltage V _inv can be changed by changing the switching timing of the switching elements Q1 and Q3 and the switching timing of the switching elements Q2 and Q4. For example, by advancing the switching timing of the switching elements Q2 and Q4 with respect to the state shown in FIG. 4, the duty of the output voltage V _inv can be made smaller than 0.25 (the minimum value is 0), and the switching elements By delaying the switching timing of Q2 and Q4, the duty of the output voltage V _inv can be made larger than 0.25 (the maximum value is 0.5).

By adjusting the duty of the output voltage V _inv , the magnitude of the output power of the inverter 120, and thus the magnitude of the transmitted power (power supplied to the LC resonance circuit R1) can be changed. Qualitatively, the output power of the inverter 120 can be increased by increasing the duty, and the output power of the inverter 120 can be decreased by decreasing the duty. Therefore, power transmission ECU 150 can bring the magnitude of the output power of inverter 120 close to the target power (for example, charging power command value Ps described later) by adjusting the duty of output voltage V _inv .

When the resonance frequency of each of the LC resonance circuits R1 and R2 matches the drive frequency of the inverter 120, the output impedance Z _inv of the inverter 120 can be expressed by the following equations (1) to (5). Further, the output current I _inv of the inverter 120 can be expressed by the following equation (6). Further, the INV phase difference φ of the inverter 120 can be expressed by the following equation (7). The INV phase difference φ is a phase difference between the INV voltage phase (the phase of the output voltage of the inverter 120) and the INV current phase (the phase of the output current of the inverter 120).

In Expression (1), j is an imaginary unit. In Expressions (2), (3), and (7), x _m is the impedance with respect to the mutual inductance between the LC resonance circuit R1 and the LC resonance circuit R2, and R _L is the input impedance to the rectification circuit 206 (See FIG. 2). In Expression (6), V _inv is the output voltage of the inverter 120. In Expressions (2) to (5) and (7), x _C11 , x _L11 , x _C21 , and x _L21 are impedances with respect to the circuit constants of the capacitor 103, the coil 104, the capacitor 203, and the variable inductor 204, respectively.

In the power transmission unit 100, the output power factor λ of the inverter 120 and the INV phase difference φ of the inverter 120 satisfy the relational expression such as “λ=|cos φ|”. The INV phase difference φ is expressed with reference to the voltage phase. When the INV current phase deviates to the retard side with respect to the INV voltage phase, the INV phase difference φ has a negative value, and when the INV current phase deviates to the advance side with respect to the INV voltage phase. Indicates that the INV phase difference φ has a positive value. For example, if the INV phase difference φ is 0° (no phase difference), the output power factor λ of the inverter 120 is 1 (active power only), and if the INV phase difference φ is 90° or −90°, the inverter 120 is. Output power factor λ of 0 becomes 0 (only reactive power). A larger INV phase difference φ means that the INV current phase advances with respect to the INV voltage phase, and a smaller INV phase difference φ means that the INV current phase retards with respect to the INV voltage phase. Means

By the way, when non-contact power transmission is performed from the LC resonance circuit R1 of the power transmission unit 100 to the LC resonance circuit R2 of the power reception unit 200, the alignment between the primary coil 101 and the secondary coil 201 is insufficient, and the position If there is a deviation (a deviation from the facing position), the distance between the primary coil 101 and the secondary coil 201 (more specifically, the center of the primary coil 101 and the center of the secondary coil 201 are connected to each other). The three-dimensional distance corresponding to the length of the line) becomes longer, and the INV current phase tends to shift toward the advance side with respect to the INV voltage phase (for details, see FIG. 8 described later). When the INV current phase shifts to the advance side with respect to the INV voltage phase, the turn-on current of the inverter 120 increases and the switching loss of the inverter 120 tends to increase.

Therefore, the vehicle 2 according to the present embodiment receives the inverter information indicating the magnitude of the turn-on current of the inverter 120 from the power transmission unit 100, and the larger the turn-on current, the power receiving inductance L ₂₁ (the inductance of the variable inductor 204). Is configured to be small. The inverter information is received by the communication device 600, and the power receiving inductance L ₂₁ is controlled by the vehicle ECU 500.

FIG. 5 is a diagram for explaining power receiving inductance control (L ₂₁ control) by vehicle ECU 500. Referring to FIG. 5, vehicle ECU 500 determines whether or not the turn-ON current exceeds a predetermined threshold value X _T (hereinafter, also simply referred to as “X _T ”), and when the turn-ON current exceeds X _T. the variable inductor 204 is controlled to the power receiving inductor _{L 21} first value (hereinafter, _{"L L"} also hereinafter) while, in the case where the turn oN current does not exceed _{X T} is variable inductor 204 To set the power receiving inductance L ₂₁ to a second value larger than L _L (hereinafter, also referred to as “L _H ”). In this embodiment, X _T is 0A. However, the present invention is not limited to this, and X _T may be set to a value larger than 0 A (for example, 10 A or 20 A). In this embodiment, each of L _H and L _L has a fixed value, but at least one of L _H and L _L may be variably set according to a predetermined parameter.

Vehicle 2 according to the present embodiment can suppress the turn-on current of inverter 120 in power transmission unit 100 by performing the power receiving inductance control when power is received from power transmission unit 100 in a contactless manner. Hereinafter, the operation and effect produced by the vehicle 2 will be described with reference to FIGS. 6 to 9.

It is considered that the INV current phase shifts to the advance side with respect to the INV voltage phase as the turn-ON current of the inverter 120 increases. FIG. 6 is a diagram showing an output voltage waveform and an output current waveform of the inverter 120 when the INV current phase is shifted to the advance side with respect to the INV voltage phase. In FIG. 6, the line L21 shows the output voltage waveform of the inverter 120, and the line L22 shows the output current waveform of the inverter 120. Referring to FIG. 6, as indicated by lines L21 and L22, the INV current phase is shifted toward the advance side with respect to the INV voltage phase, so that the turn-ON current of inverter 120 is increased.

FIG. 7 is a diagram showing an output voltage waveform and an output current waveform of the inverter 120 when the INV phase difference φ is 0 (that is, the INV voltage phase and the INV current phase match). In FIG. 7, a line L31 shows an output voltage waveform of the inverter 120, and a line L32 shows an output current waveform of the inverter 120. Referring to FIG. 7, as shown by lines L31 and L32, when the INV phase difference φ is 0, the turn-on current of the inverter 120 becomes 0.

As described above, the turn-on current of the inverter 120 increases as the INV current phase shifts toward the advance side with respect to the INV voltage phase. The turn-ON current of the inverter 120 corresponds to the current at the moment when the switch of the inverter 120 switches from OFF to ON. Regarding the magnitude of the turn-on current of the inverter 120, the current in the rising direction (High direction) of the output voltage of the inverter 120 is positive (+), and the current in the falling direction (Low direction) of the output voltage of the inverter 120 is negative ( −). In the inverter 120, it is determined that the turn-on current is larger as the amount of output current in the High direction is larger when the output voltage rises. Further, in the inverter 120, it is determined that the turn-ON current is smaller as the output current amount in the Low direction is larger when the output voltage rises. When the INV current phase shifts to the retard side with respect to the INV voltage phase, the turn-on current has a negative value. That is, when the INV current phase shifts to the retard side with respect to the INV voltage phase, the turn-ON current becomes smaller. When the turn-on current has a positive value (>0 A), the inverter 120 is in hard switching, and switching loss increases. On the other hand, the negative turn-on current (turn-on current in the low direction) is considered to have almost no effect on the switching loss of the inverter 120.

As described above, when the alignment between the primary coil 101 and the secondary coil 201 is insufficient, the distance between the primary coil 101 and the secondary coil 201 (hereinafter, also simply referred to as “inter-coil distance”) become longer. The coupling coefficient between the primary coil 101 and the secondary coil 201 (hereinafter, also simply referred to as "coupling coefficient") tends to decrease as the inter-coil distance increases. Further, as the coupling coefficient becomes smaller, the INV current phase tends to advance with respect to the INV voltage phase. On the other hand, the smaller the power receiving inductance L ₂₁ (the inductance of the variable inductor 204), the smaller the INV phase difference φ (that is, the INV current phase retards with respect to the INV voltage phase).

FIG. 8 is a diagram showing the relationship between the INV phase difference φ and the power receiving inductance L ₂₁ in three situations in which the inter-coil distance (and thus the magnitude of the coupling coefficient) is different. In FIG. 8, lines L11, L12, and L13 show graphs in situations where the coupling coefficient is large, medium, and small, respectively.

Referring to FIG. 8, as indicated by lines L11, L12, and L13, the INV phase difference φ tends to increase as the coupling coefficient decreases (that is, the INV current phase advances with respect to the INV voltage phase). is there. In the lines L11 and L12, the INV phase difference φ is closest to 0 when L ₂₁ is a predetermined value (hereinafter, referred to as “peak value”), and the INV phase difference φ becomes 0 as the L ₂₁ deviates from the peak value. Stay away from. In this embodiment, L _H (FIG. 5) described above is set near the peak values of lines L11 and L12 (for example, a value slightly larger than the peak values). By doing so, the INV phase difference φ can be brought close to 0 when the coupling coefficient is “medium” and “large” (for example, when the coupling coefficient is a predetermined value or more).

On the other hand, when L ₂₁ is L _H and the coupling coefficient is “small” (for example, when the coupling coefficient is less than the predetermined value), the INV voltage phase is On the other hand, the INV current phase is largely deviated to the advance side. Therefore, the turn-ON current of the inverter 120 becomes large (see FIG. 6) and exceeds X _T (for example, 0 A). If the turn ON current exceeds _{X T,} it switches the power receiving inductor _{L 21} in _{L L} vehicle ECU500 controls the variable inductor 204. The INV phase difference φ is reduced by reducing the power receiving inductance L ₂₁ . In this embodiment, L ₂₁ becomes L _L when the coupling coefficient is “small”, so that the INV phase difference φ becomes a value close to 0. As the INV phase difference φ decreases, the turn-ON current also decreases (see FIG. 7).

FIG. 9 is a diagram showing a relationship between the power receiving inductance L ₂₁ and the turn-ON current when the coupling coefficient is “small”. Referring to FIG. 9, the turn-ON current tends to decrease as the power receiving inductance L ₂₁ decreases. In the example of FIG. 9, the turn-ON current when L ₂₁ is L _H is about 17 A, and the turn-ON current when L ₂₁ is L _L is about 0 A. The turn-ON current can be reduced by switching L ₂₁ from L _H to L _L.

Next, an example of a processing procedure for charging the power storage device 300 of the vehicle 2 by the charging facility 1 by incorporating the above-described inductance control into the non-contact charging control will be described.

First, the driver stops the vehicle 2 in the charging space of the charging facility 1. Then, at the stop position of vehicle 2, after establishing a communication connection (for example, connection to a wireless LAN) between vehicle ECU 500 and power transmission ECU 150, power transmission request is sent from vehicle ECU 500 to power transmission ECU 150. The power transmission request may be transmitted according to a driver's instruction, or may be automatically transmitted when a predetermined condition is satisfied.

When power transmission ECU 150 receives this power transmission request, verification of charging information (for example, information indicating the specifications of charging facility 1) and vehicle information (for example, information indicating the specifications of vehicle 2) is performed between power transmission ECU 150 and vehicle ECU 500. Done. Based on the result of this comparison, it is determined whether or not the charging facility 1 can charge the vehicle 2. The vehicle information includes the vehicle type (or identification number) of the vehicle 2, the rated voltage of the power storage device 300, and the like. In addition, the charging information includes the supply power of the charging facility 1, the maximum output voltage, and the like. If the specifications of the vehicle 2 correspond to the specifications of the charging facility 1, the power transmission ECU 150 and the vehicle ECU 500 determine that the vehicle 2 can be charged (chargeable) by the charging facility 1, and prepare for the power transmission described below. move on. On the other hand, when the specifications of vehicle 2 do not correspond to the specifications of charging facility 1 (for example, when the maximum output voltage of charging facility 1 is too high or too low with respect to the rated voltage of power storage device 300), power transmission ECU 150 The vehicle ECU 500 determines that the vehicle 2 cannot be charged by the charging facility 1 (cannot be charged), and stops the charging process.

When it is determined by the above collation that the battery can be charged, the power transmission ECU 150 starts the power transmission preparation. The power transmission preparation is a process for making the power transmission system 10 ready for power transmission. For example, the power transmission unit 100 and the power reception unit 200 are aligned with each other as the power transmission preparation. In addition, when charging facility 1 includes a plurality of power transmission units, a process for specifying which power transmission unit has been aligned (so-called pairing) may be performed as the power transmission preparation. .. Various methods are known as a method for alignment and pairing, and any method can be adopted.

When the power transmission preparation is completed, non-contact power transmission is performed between power transmission ECU 150 of charging facility 1 and vehicle ECU 500 of vehicle 2, and power storage device 300 of vehicle 2 is charged by the power supplied from charging facility 1. To be done.

FIG. 10 is a flowchart showing a processing procedure of charging control executed by vehicle ECU 500 after the above-mentioned collation and power transmission preparation are completed. The processes shown in this flowchart are steps S11 to S17, S21 to S23, S31 to S32 (hereinafter, simply referred to as "S11" to "S17", "S21" to "S23", "S31" to "S32"). including.

Referring to FIG. 10, vehicle ECU 500 performs initialization (S11). More specifically, vehicle ECU 500 controls variable inductor 204 to set power receiving inductance L ₂₁ to L _H (initial value). Further, vehicle ECU 500 initializes the error information stored in the storage device. Initially, the error information indicates that no abnormality has occurred.

Next, vehicle ECU 500 turns on (closes) charging relay 400 (S12). The following S13, S21, S14, S15, S22, and S16 (hereinafter, may be referred to as “loop processing S13 to S16”) are before charging and during charging (except when an abnormality occurs). Is repeatedly executed.

In S13, vehicle ECU 500 determines whether or not an abnormality has occurred on the power receiving side. Vehicle ECU 500 determines, for example, that the voltage and current of each part of power reception unit 200 (the output voltage of power reception unit 200 detected by monitoring unit 310, the current detected by current sensors 283, 284, etc.) are within a predetermined allowable range. Determine if there is. When at least one of the voltage and the current of each part of the power receiving unit 200 is not within the allowable range (for example, when the overvoltage and/or the overcurrent is generated), it is determined that the abnormality occurs on the power receiving side.

The method of determining whether there is an abnormality is arbitrary. For example, vehicle ECU 500 may determine that an abnormality occurs on the power receiving side when the temperature of a predetermined portion of power receiving unit 200 or the temperature of power storage device 300 is excessively high.

If no abnormality has occurred on the power receiving side (NO in S13), the process proceeds to S21. In S21, vehicle ECU 500 determines whether or not an L ₂₁ change request (see step S83 in FIG. 12 described later) is received from power transmission unit 100.

The L ₂₁ change request is a signal indicating that the turn-ON current of the inverter 120 is large. The L ₂₁ change request is transmitted from the power transmission unit 100 to the vehicle 2 when the turn-ON current is large. Although details will be described later, the L ₂₁ change request is transmitted toward the vehicle 2 when the power transmission unit 100 detects a turn-ON current exceeding a predetermined threshold value X _T. In the vehicle 2, the communication device 600 receives the L ₂₁ change request. The vehicle ECU 500 receives the L ₂₁ change request from the communication device 600.

When it is determined that it has received the L ₂₁ change request (YES in S21), the vehicle ECU500 is, changes the _{L 21} from _{L H} in S32 in _L L _(L less than _H), the _{L 21} A signal indicating that the change is completed (hereinafter, referred to as “L ₂₁ change completion notification”) is transmitted to the power transmission unit 100. Then, the process proceeds to S14. On the other hand, if it is determined that the L ₂₁ change request has not been received (NO in S21), the process proceeds to S14 without performing the process of S32.

In S14, vehicle ECU 500 calculates charging power command value Ps (hereinafter sometimes simply referred to as "Ps") based on the state of power storage device 300 detected by monitoring unit 310, and the obtained calculated value is obtained. To the storage device. More specifically, vehicle ECU 500 decreases charging power command value Ps as SOC of power storage device 300 approaches full charge (100%). Note that the SOC measurement method is arbitrary, and a method using current value integration (Coulomb count), a method using open circuit voltage (OCV) estimation, or the like can be adopted.

In S15, vehicle ECU 500 causes power supplied from power reception unit 200 to power storage device 300 based on the current and voltage of power storage device 300 detected by monitoring unit 310 (hereinafter, “actual charging power P _out ”, or (Hereinafter, simply referred to as “P _out ”) is detected, and the obtained detection value is stored in the storage device.

In S22, vehicle ECU 500 controls communication device 600 to transmit information to power transmission unit 100. Predetermined information (for example, Ps and P _out ) is transmitted from the communication device 600 to the power transmission unit 100. The information transmitted from the communication device 600 is received by the communication device 160 in the power transmission unit 100.

In S16, vehicle ECU 500 determines whether charging is completed. Vehicle ECU 500 determines that charging is completed, for example, when a predetermined completion condition is satisfied. The completion condition is satisfied, for example, when the SOC of power storage device 300 becomes equal to or higher than a predetermined SOC value during charging. The predetermined SOC value may be automatically set by vehicle ECU 500 or the like, or may be set by the user.

In this embodiment, the above completion condition is satisfied when the SOC of power storage device 300 is fully charged (100%) during charging. However, the present invention is not limited to this, and the above completion condition can be set arbitrarily. For example, the completion condition may be satisfied when the charging time (elapsed time from the start of charging) becomes longer than a predetermined value. Further, the completion condition may be established when the user gives an instruction to stop charging during charging.

If charging is not completed (NO in S16), the process returns to S13. The loop processes S13 to S16 are repeatedly executed until it is determined in S16 that the charging is completed (YES in S16) or the abnormality is determined in S13 (YES in S13).

When YES is determined in any of S13 and S16, the charging stop process (S23 and S17) described below is performed. However, if YES is determined in S13, after the processing in S31, the charge stop processing (S23 and S17) is forcibly performed without waiting for the completion of charging. In S31, vehicle ECU 500 updates the error information stored in the storage device. As a result, the fact that an abnormality has occurred and the content of the abnormality are written in the error information. By referring to the error information after the charging is stopped, it is possible to know whether the charging is normally completed and stopped, or whether an abnormality occurs during charging and the charging is forcibly stopped.

In S23, vehicle ECU 500 controls communication device 600 to transmit information to power transmission unit 100. Predetermined information (for example, power transmission stop request and error information) is transmitted from communication device 600 to power transmission unit 100. The information transmitted from the communication device 600 is received by the communication device 160 in the power transmission unit 100.

Subsequently, the vehicle ECU 500 turns off (opens) the charging relay 400 (S17). As a result, the power supply path to power storage device 300 is cut off, and power is not supplied to power storage device 300 (and thus power storage device 300 is not charged). With this S17, the processing of FIG. 10 ends.

FIG. 11 is a flowchart showing a processing procedure of power transmission control executed by the power transmission ECU 150 after the above-described collation and power transmission preparation are completed. The process shown in this flowchart includes steps S51 to S58, S61, and S62 (hereinafter, simply referred to as "S51" to "S58", "S61", and "S62").

Referring to FIG. 11, power transmission ECU 150 sets 0 (initial value) to ΔPs used in S55 and S56 described later and S76 of FIG. 12 (S51). Subsequently, the power transmission ECU 150 sets a predetermined minimum value as the drive frequency f in the drive signal of the inverter 120 (S52). In this embodiment, the minimum value of the drive frequency f is 81.4 kHz.

Next, the transmission power is adjusted by controlling the duty of the output voltage of the inverter 120 (S61). FIG. 12 is a flowchart showing the processing procedure of this duty control. The processes shown in this flowchart are steps S71 to S78, S80 to S84, S91, and S92 (hereinafter, simply referred to as "S71" to "S78", "S80" to "S84", "S91", and "S92"). including.

Referring to FIG. 12, power transmission ECU 150 sets a predetermined minimum value as duty D (hereinafter, also simply referred to as “duty D”) of the output voltage in the drive signal of inverter 120 (S71). In this embodiment, the minimum value of the duty D is 0.

Next, the power transmission ECU 150 determines whether or not a power transmission stop request (S23 in FIG. 10) has been received from the vehicle 2 (S72). When it is determined that the power transmission stop request has not been received (NO in S72), power transmission ECU 150 determines whether or not an abnormality has occurred on the power transmission side (S73). The method of determining whether there is an abnormality in S73 is arbitrary. For example, power transmission ECU 150 may determine that an abnormality has occurred on the power transmission side when the temperature of a predetermined portion of power transmission unit 100 is excessively high.

When there is no abnormality on the power transmission side (NO in S73), power transmission ECU 150 drives inverter 120 and AC/DC converter 130 to execute power transmission from primary coil 101 to secondary coil 201. (S74). AC/DC converter 130 is controlled such that the input voltage (DC voltage) of inverter 120 is constant, for example. Regarding the drive signal of the inverter 120, the drive frequency f and the duty D of the output voltage are set to the values set in S52 or S53 of FIG. 11 and S71 or S77 of FIG. As the drive frequency f, the minimum value set in S52 of FIG. 11 is used initially, but the value set in S53 is used when the process of S53 of FIG. 11 described later is performed. Further, the duty D of the output voltage initially has the minimum value set in S71, but increases by a predetermined amount each time the process of S77 described below is executed.

In S75, power transmission ECU 150 determines whether or not the current of each part of power transmission unit 100 (for example, the current detected by current sensors 182 to 184) is within a predetermined allowable range. When at least one of the currents of each part of the power transmission unit 100 is not within the allowable range (for example, when an overcurrent occurs), NO is determined in S75, and all the currents of each part of the power transmission unit 100 are within the allowable range. If it is within the range, YES is determined in S75.

If NO is determined in S75, it is highly likely that the drive frequency f does not match, so the process is returned to the main routine (process in FIG. 11), and the duty control at the current drive frequency f is performed. finish. The process proceeds to S53 in FIG.

If YES is determined in S75, power transmission ECU 150 determines in S80 whether it is the rising timing of the output voltage of inverter 120. Then, if it is the rising timing of the output voltage of inverter 120 (YES in S80), power transmission ECU 150 determines in S81 that the output current of inverter 120 detected by current sensor 183 (that is, the turn-ON current) is predetermined. Threshold value X _T (for example, 0 A) is determined. The determination of YES in S81 means that the turn-ON current is large. In this embodiment, the coupling coefficient is turned ON current only if it is less than the predetermined value is greater than X _T (see FIGS. 6 to 8 described above).

When the turn-ON current is large (YES in S81), power transmission ECU 150 sets inverter 120 and AC/DC converter 130 in a stopped state (non-driven state) to stop power transmission in S82. Subsequently, in S83, the power transmission ECU150 _sends a signal requesting a change of _{L 21} a _{(L 21} change request) to the vehicle 2. Only when the turn-ON current is large (YES in S81), the L ₂₁ change request is transmitted to vehicle 2. Therefore, for the vehicle ECU 500, the L ₂₁ change request is a signal requesting the change of L ₂₁ and also a signal indicating that the turn-ON current is large. The L ₂₁ change request according to this embodiment corresponds to an example of “inverter information” according to the present disclosure.

When the vehicle ECU 500 receives the L ₂₁ change request, the vehicle ECU 500 changes the power receiving inductance L ₂₁ from L _H to L _L and transmits an L ₂₁ change completion notification to the power transmission unit 100 (see S32 in FIG. 10 ). By changing L ₂₁ to L _L in the power receiving unit 200, the turn-ON current becomes small (see FIG. 9 described above).

After transmission of the L ₂₁ change request transmission ECU150 waits for _{L 21} change completion notification from the vehicle 2 _receives the _{L 21} change completion notification, in S84, by driving the inverter 120 and AC / DC converter 130, 1 Power transmission from the secondary coil 101 to the secondary coil 201 is restarted. Then, the process is returned to S72.

If it is determined not to be the rising timing of the output voltage of the inverter 120 (NO) at S80, and when the turn ON current is determined to be less than _{X T} (NO) at S81, the process proceeds to S76. In S76, power transmission ECU 150 determines whether or not the deviation between charging power command value Ps and actual charging power P _out is sufficiently small.

Charging power command value Ps is generated in vehicle ECU 500 (see S14 in FIG. 10) and transmitted from vehicle 2 to power transmission unit 100 (see S22 in FIG. 10). When ΔPs is 0 (initial value) (see S51 in FIG. 11 ), power transmission ECU 150 directly uses the value received from vehicle 2 as charging power command value Ps in S76. On the other hand, when the process of S55 of FIG. 11 described later is performed, ΔPs becomes a value larger than 0, and ΔPs corrects the charging power command value Ps. In this case, power transmission ECU 150 uses a value obtained by subtracting ΔPs from the value received from vehicle 2 as charging power command value Ps in S76.

Actual charging power P _out is generated in vehicle ECU 500 (see S15 in FIG. 10) and transmitted from vehicle 2 to power transmission unit 100 (see S22 in FIG. 10). In S76, power transmission ECU 150 uses the value received from vehicle 2 as it is as actual charging power P _out .

In S76, by using the Ps and _{P out,} the calculated deviation between Ps and _{P out,} whether the deviation is sufficiently small or not. The deviation is a parameter indicating a deviation (degree of difference) between two values. As the deviation, a difference or a ratio can be adopted. The larger the difference (absolute value), the larger the deviation. Further, the closer the ratio is to 1, the smaller the deviation. In this embodiment, in S76, the power transmission ECU 150 determines whether or not the difference between Ps and P _out (|Ps−P _out |) is less than or equal to a predetermined threshold Th1 (hereinafter, also simply referred to as “Th1”). to decide.

If it is determined NO in S76 in (| | _{Ps-P out} is larger than Th1), the transmission ECU150 is a unit operation amount than the current value of the duty D of the output voltage in the drive signal of the inverter 120 [Delta] D only Increase (S77). Subsequently, the power transmission ECU 150 determines whether the duty D is equal to or less than a predetermined threshold Th2 (hereinafter, also simply referred to as “Th2”) (S78). Th2 corresponds to the maximum value of the duty D. In this embodiment, Th2 (maximum value of duty D) is set to 0.5. If duty D does not become larger than Th2 even after the process of S77 (YES at S78), the process returns to S72.

Also, when YES is determined in S76, the process is returned to S72. The determination of YES in S76 means that the duty D at which |Ps−P _out | is Th1 or less exists in the range (0.0 to 0.5) from the minimum value to the maximum value of the duty D. means. If the duty D so that the deviation between the Ps and P _out during the transmission is sufficiently small is adjusted, so that stable transmission is performed. If continued transmission under the same conditions after the adjustment of the duty D, and basically, the deviation between the Ps and P _out is kept small, it does not occur overcurrent. Therefore, if YES is determined in S76, the power transmission stop request is received from vehicle 2 (YES in S72) or until it is determined that an abnormality has occurred in S73 (YES in S73). , S72 to S76 are repeatedly executed, and stable power transmission is continued.

Further, if NO is determined in S78 (the duty D is larger than Th2), it means that |Ps−P is in the range (0.0 to 0.5) from the minimum value to the maximum value of the duty D. It means that there is no duty D in which _out | becomes Th1 or less. If NO is determined in S78, the process is returned to the main routine (the process of FIG. 11), and the duty control at the current drive frequency f ends. The process proceeds to S53 in FIG.

When YES is determined in any of S72 and S73, power transmission stop processing (S91 and S92) described below is performed.

In S91, the power transmission ECU 150 sets the inverter 120 and the AC/DC converter 130 to a stopped state (non-driving state) to stop power transmission. In S92, power transmission ECU 150 controls communication device 160 to transmit information to vehicle 2. Predetermined information (for example, a power transmission stop notification indicating completion of power transmission stop) is transmitted from communication device 160 to vehicle 2. When the power transmission is stopped due to the occurrence of an abnormality (YES in S73), an abnormality occurrence notification indicating that an abnormality has occurred may be transmitted from communication device 160 to vehicle 2. The information transmitted from the communication device 160 is received by the communication device 600 in the vehicle 2. With this S92, not only the processing of FIG. 12 but also the processing of FIG. 11 (power transmission control by the power transmission ECU 150) ends.

Referring to FIG. 11 again, if NO in either S75 or S78 of FIG. 12, the process proceeds to S53. In S53, power transmission ECU 150 increases drive frequency f in the drive signal of inverter 120 by the unit operation amount Δf from the current value. Subsequently, the power transmission ECU 150 determines whether the drive frequency f is less than a predetermined threshold Th3 (hereinafter, also simply referred to as “Th3”) (S54). In this embodiment, Th3 (upper limit value of drive frequency f) is set to 90.0 kHz. If the drive frequency f does not exceed Th3 or higher even after the process of S53 (YES in S54), the above-described duty control (process of FIG. 12) is executed at the drive frequency f (S62).

The determination of NO in S54 (the drive frequency f becomes Th3 or more) means that the duty control (duty adjustment range: 0.0 to 0.5) is performed while changing the drive frequency f. This means that there is no drive frequency f at which |Ps−P _out | becomes Th1 or less within the adjustment range (81.4 kHz to 90.0 kHz) of the drive frequency f (see S76 in FIG. 12). If NO is determined in S54, the process proceeds to S55.

In S55, the power transmission ECU 150 decreases the charging power command value Ps by increasing ΔPs indicating the correction amount (more specifically, the decrease amount) of the charging power command value Ps by a unit operation amount from the current value. .. ΔPs is used in the process of FIG. In S76 of FIG. 12, the charging power command value Ps received from the vehicle 2 is subtracted and corrected (Ps−ΔPs) by ΔPs. The larger ΔPs is, the smaller Ps after correction becomes. Each time the process of S55 is executed, ΔPs increases by the unit operation amount. The unit operation amount can be set arbitrarily.

Subsequently, power transmission ECU 150 determines whether or not ΔPs is equal to or greater than a predetermined threshold value Th4 (hereinafter also simply referred to as “Th4”) (S56). If ΔPs does not become Th4 or more even after the process of S55 (NO in S56), the process returns to S52. Then, the drive frequency f and the duty D are adjusted again for the charging power command value Ps that is decreased by the process of S55.

If YES is determined in S56 (ΔPs becomes Th4 or more), |Ps−P _out | becomes Th1 or less even if the charging power command value Ps is decreased in the adjustment range (0 to Th4) of ΔPs. It means that it did not happen (see S76 in FIG. 12). If YES is determined in S56, power transmission stop processing (S57 and S58) is performed. S57 and S58 are processes according to S91 and S92 of FIG. 12 described above. That is, in S57, the power transmission ECU 150 sets the inverter 120 and the AC/DC converter 130 in a stopped state (non-driving state) to stop power transmission. In S58, power transmission ECU 150 controls communication device 160 to transmit information to vehicle 2. With this S58, the processing of FIG. 11 (power transmission control by the power transmission ECU 150) ends.

As described above, the power transmission system 10 according to this embodiment is configured to transmit power from the LC resonance circuit R1 of the power transmission unit 100 to the LC resonance circuit R2 of the vehicle 2 in a contactless manner.

The power transmission unit 100 includes an LC resonance circuit R1, an inverter 120 that converts DC power into AC power and outputs the AC power to the LC resonance circuit R1, and inverter information that indicates the magnitude of the turn-ON current of the inverter 120 (for example, in FIG. A first communication device (for example, communication device 160 and power transmission ECU 150) that transmits the L ₂₁ change request transmitted in S83 to vehicle 2. The power transmission ECU 150 transmits the inverter information to the vehicle 2 via the communication device 160.

The vehicle 2 includes an LC resonance circuit R2, a rectification circuit 206 that converts AC power received by the LC resonance circuit R2 in a contactless manner into DC power, and an inductance (power reception inductance) between the LC resonance circuit R2 and the rectification circuit 206. comprising L ₂₁₎ and configured to be able to change the filter circuit F2 and the vehicle ECU500 to control the filter circuit F2, and a communication device 600 that receives inverter information from the power transmitting unit 100. The filter circuit F2 includes the variable inductor 204, and the vehicle ECU 500 is configured to control the variable inductor 204. Whether the communication device 600 receives the L ₂₁ change request is determined in S21 of FIG.

The vehicle ECU 500 is configured such that the larger the turn-ON current indicated by the above inverter information, the smaller the power receiving inductance L ₂₁ by the variable inductor 204. More specifically, the vehicle ECU500 has received the _{L 21} change request in S21 in FIG. 10 (i.e., turn ON current is large) if it is determined that (YES in S21), the the _{L 21} in S32 Switch from L _H to L _L (value smaller than L _H ).

As described above, by reducing the extent receiving inductance L ₂₁ turns ON current increases, it is possible reduce the INV phase difference. As the INV phase difference decreases, the turn-ON current also decreases. When the power receiving unit 200 receives power from the power transmitting unit 100 in a contactless manner, the vehicle ECU 500 controls the variable inductor 204 to adjust the power receiving inductance L ₂₁ to suppress the turn-on current of the inverter 120 in the power transmitting unit 100. can do.

In the power transmission system 10 according to this embodiment, the circuit constant is adjusted not in the configuration of the charging facility 1 but in the configuration of the vehicle 2 (more specifically, the variable inductor 204). In general, a vehicle is easier to change its configuration (change of hardware configuration) than a charging facility. Therefore, it is possible to provide the method according to the above-described embodiment as a method of suppressing the turn-on current of the inverter in the charging facility. Be beneficial.

The vehicle ECU 500 may be configured to switch the power receiving inductance L ₂₁ in multiple stages according to the magnitude of the turn-on current, using a plurality of thresholds for determining the magnitude of the turn-on current of the inverter 120. Good. The vehicle ECU500 may be configured to adjust the power receiving inductance L ₂₁ continuously so as to follow the turn ON power receiving inductance L ₂₁ with a change in the current of the inverter 120 in real time.

The circuit configuration of the power transmission system 10 is not limited to the configuration shown in FIG. For example, the LC resonance circuits R1 and R2 are not limited to the series resonance circuit shown in FIG. At least one of the LC resonance circuits R1 and R2 may be configured by connecting a coil and a capacitor in parallel. The LC filter of the power receiving unit 200 is not limited to the π-type LC filter shown in FIG. 2, but may be another type of LC filter (for example, an L-type LC filter in which the capacitor 205 shown in FIG. 2 is omitted). May be. Furthermore, the position of the variable inductor 204 that constitutes the LC filter of the power receiving unit 200 may be changed. FIG. 13 is a diagram showing a modified example of the circuit configuration of the power transmission system 10. Referring to FIG. 13, in this example, variable inductor 204 is provided not on power line PL2 but on power line PL1.

Changeable configured inductance adjusting circuit receiving the inductance L ₂₁ is not limited to the filter circuit F2. Instead of the variable inductor 204, the variable inductance circuits 204A and 204B shown in FIGS. 14 and 15 may be adopted. FIG. 14 is a diagram showing a first modification of the inductance adjusting circuit. FIG. 15 is a diagram showing a second modification of the inductance adjusting circuit.

Referring to FIG. 14, the variable inductance circuit 204A includes a coil 211, a coil 212 and a switch 213 connected in parallel to the coil 211, as elements connected in series to the secondary coil 201 (see FIG. 2). It is configured to include. The coil 212 and the switch 213 are connected in series with each other. The inductance of the variable inductance circuit 204A changes depending on the state (ON/OFF) of the switch 213. More specifically, when the inductances of the coils 211 and ₂₁₂ are expressed as L ₂₁₁ and L ₂₁₂ , respectively, the inductance of the inductance variable circuit 204A when the switch 213 is OFF is “L ₂₁₁ ”and the switch 213 is ON. At this time, the inductance of the inductance variable circuit 204A is “L ₂₁₁ ×L ₂₁₂ /(L ₂₁₁ +L ₂₁₂ )”.

Referring to FIG. 15, the variable inductance circuit 204B includes coils 221, 222 and a switch 223 connected in parallel with the coil 222 as elements connected in series to the secondary coil 201 (see FIG. 2). Composed of. The coils 221 and 222 are connected to each other in series. The inductance of the variable inductance circuit 204B changes depending on the state (ON/OFF) of the switch 223. More specifically, when the inductances of the coils ₂₂₁ and ₂₂₂ are expressed as L ₂₂₁ and L ₂₂₂ , respectively, the inductance of the inductance variable circuit 204B when the switch 223 is OFF is “L ₂₂₁ +L ₂₂₂ ”and the switch 223 is ON. The inductance of the variable inductance circuit 204B is “L ₂₂₁ ”.

In the processes of FIGS. 10 to 12, the power reception inductance L ₂₁ is changed after the power transmission is stopped, and the power transmission is restarted after the change. A mechanical relay that does not require a relay and is easily available at a lower cost than a semiconductor relay can be used. However, the type of each switch is not limited to the mechanical relay. A semiconductor relay may be adopted instead of the mechanical relay.

The processing of FIGS. 10 to 12 is an example of power transmission/reception control and is not limited to this. For example, an extreme value search of the drive frequency of the inverter 120 (search for a frequency at which the power loss is minimized) is performed, and then the duty of the output voltage of the inverter 120 is adjusted to an optimum value at the searched frequency (extreme value). Good.

The target to which the non-contact power receiving device is applied is not limited to the vehicle and is arbitrary. The application target of the non-contact power receiving device may be, for example, another vehicle (ship, airplane, etc.) or an unmanned moving body (automatic guided vehicle (AGV), agricultural machine, drone, etc.). However, it may be a mobile device (smartphone, wearable device, etc.) or a building (house, factory, etc.).

The target device to which the power is supplied from the non-contact power receiving device is not limited to the power storage device, and may be any electric load (vehicle-mounted device, household electric device, etc.).

Each of the above modifications may be implemented in whole or in combination.
It should be considered that the embodiments disclosed this time are exemplifications in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

1 Charging Equipment, 2 Vehicles, 10 Power Transmission System, 100 Power Transmission Unit, 101 Primary Coil, 102, 103, 202, 203, 205, 207 Capacitor, 104, 211, 212, 221, 222 Coil, 120 Inverter, 130 AC /DC converter, 150 power transmission ECU, 160,600 communication device, 181 voltage sensor, 182, 183, 184, 283,284 current sensor, 200 power receiving unit, 201 secondary coil, 204 variable inductor, 204A, 204B inductance variable circuit, 206 rectifier circuit, 213, 223 switch, 300 power storage device, 310 monitoring unit, 400 charging relay, 500 vehicle ECU, 700 AC power supply, Cb1, Cb2 capacitor, D10 bridge circuit, F1, F2 filter circuit, R1, R2 LC resonant circuit ..

Claims (1)

A non-contact power transmission system for wirelessly transmitting power from a power transmission unit of a non-contact power transmission device to a power reception unit of a non-contact power receiving device,
The non-contact power transmission device includes a power transmission circuit that configures the power transmission unit, an inverter that converts DC power into AC power and outputs the AC power to the power transmission circuit, and an output current of the inverter when the output voltage of the inverter rises. A first communication device for transmitting inverter information indicating the magnitude of a certain turn-on current to the non-contact power receiving device,
The non-contact power receiving device includes a power receiving circuit that constitutes the power receiving unit, a rectifying circuit that converts AC power received by the power receiving circuit in a non-contact manner into DC power, and between the power receiving circuit and the rectifying circuit. An inductance adjusting circuit configured to change the inductance; a control device that controls the inductance adjusting circuit; and a second communication device that receives the inverter information from the contactless power transmitting device,
The non-contact power transmission system, wherein the control device decreases the inductance by the inductance adjusting circuit as the turn-ON current indicated by the inverter information increases.

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