JP2019213267A - Non-contact transmission apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power transmission device in which an output power factor of an inverter can be easily increased in a wide coupling coefficient range. A non-contact power transmission device includes an inverter 120, an AC / DC converter 130, an LC resonance unit R1, a filter circuit F1, and a power transmission ECU 150. The AC / DC converter 130 is configured to be able to change the voltage of DC power input to the inverter 120 (input DC voltage). The filter circuit F1 includes a capacitance adjusting unit 103 configured to change the filter capacitance. The power transmission ECU 150 determines whether the coupling coefficient between the primary coil 101 and the secondary coil 201 is large or small. When the coupling coefficient is small, the input DC voltage and the filter capacitance are set to the first state, and the coupling coefficient is If so, it places the input DC voltage and the filter capacitance in the second state. In the second state, the input DC voltage is lower and the filter capacitance is smaller than in the first state. [Selection diagram] Figure 2

Description

  The present disclosure relates to a contactless power transmission device, and more particularly, to a contactless power transmission device that transmits power from a primary coil to a secondary coil of a power receiving device in a contactless manner.

  There is known a non-contact power transmission system for transmitting power in a non-contact manner from a primary coil (hereinafter also referred to as “power transmission coil”) of a power transmission device to a secondary coil (hereinafter also referred to as “power reception coil”) of the power reception device. (See Patent Documents 1 to 6). For example, in the non-contact power transmission system described in JP-A-2006-195512 (Patent Document 6), the power transmission device includes an inverter that converts DC power into AC power and a control unit that controls the inverter. And the control part is suppressing that an excessively large electric current (overcurrent) flows into a power transmission coil by adjusting the output voltage of an inverter so that the current which flows into a power transmission coil may become below a threshold value.

JP2013-154815A JP2013-146154A JP2013-146148A JP 2013-110822 A JP 2013-126327 A JP-A-2006-195512

  By the way, when the output power factor (ratio of active power to apparent power) of the inverter of the power transmission device decreases, the efficiency of the non-contact power transmission system (hereinafter also referred to as “system efficiency”) decreases. For this reason, the circuit constant in a non-contact electric power transmission system is preset so that the output power factor of the inverter of a power transmission apparatus may become high enough. The system efficiency corresponds to the energy efficiency of the entire contactless power transmission system (ratio of energy that can be recovered with respect to input energy).

  However, the coupling coefficient (hereinafter also simply referred to as “coupling coefficient”) between the primary coil (power transmission coil) and the secondary coil (power reception coil) changes under the condition that the circuit constant in the non-contact power transmission system is constant. Then, the output power factor of the inverter also changes. For example, when the circuit constant is set so that the output power factor of the inverter is high when the coupling coefficient is small, the phase of the inverter output voltage (hereinafter also referred to as “voltage phase”) is increased by increasing the coupling coefficient. ) And the phase of the output current of the inverter (hereinafter also referred to as “current phase”) increases (hereinafter also referred to as “output phase difference”), and the output power factor of the inverter decreases.

  In Patent Document 6, a decrease in the output power factor of the inverter (and hence a decrease in system efficiency) due to the change in the coupling coefficient as described above is not taken into consideration. Depending on the technique described in Patent Document 6, it is difficult to increase the output power factor of the inverter of the power transmission device in a wide coupling coefficient range.

  The present disclosure has been made to solve such a problem, and an object of the present disclosure is to provide a non-contact power transmission device that easily increases the output power factor of an inverter in a wide coupling coefficient range.

  A non-contact power transmission device (hereinafter also simply referred to as “power transmission device”) in the present disclosure is a non-contact power transmission device that performs non-contact power transmission from a primary coil to a secondary coil of a power reception device, and includes an inverter, a transformer, an LC A resonance unit, an LC filter, and a control unit are provided. The inverter is configured to convert DC power into AC power having a predetermined magnitude and frequency by pulse width modulation and output the AC power. The transformer is configured to be able to change the voltage of the DC power input to the inverter (hereinafter also referred to as “input DC voltage”). The LC resonance unit is provided on the output side of the inverter and is configured by connecting a primary coil and a capacitor in series or in parallel. The LC filter is provided between the inverter and the LC resonance unit and includes a capacitance adjustment unit. The capacitance adjustment unit is configured to change the capacitance of the LC filter (hereinafter also referred to as “filter capacitance”). The controller is configured to control the inverter, the transformer, and the capacitance adjuster.

  The control unit determines whether the coupling coefficient between the primary coil and the secondary coil is large or small. If the coupling coefficient is small, the input DC voltage and the filter capacitance are set to the first state, and the coupling is performed. When the coefficient is large, the input DC voltage and the filter capacitance are configured to be in the second state. In the second state, the input DC voltage is lower and the filter capacitance is smaller than in the first state.

  The filter capacitance in the non-contact power transmission device can be set in advance so that the output phase difference of the inverter becomes sufficiently small in accordance with a predetermined reference coupling coefficient (for example, a small coupling coefficient). Thereby, when the coupling coefficient is small, it becomes easy to ensure a sufficient output power factor of the inverter.

  However, when the coupling coefficient increases, the coupling coefficient deviates from the reference coupling coefficient. For this reason, when the coupling coefficient is large, if the filter capacitance is maintained at the value when the coupling coefficient is small, the output power factor of the inverter decreases.

  Therefore, the control unit of the non-contact power transmission apparatus according to the present disclosure makes the filter capacitance when the coupling coefficient is large smaller than the filter capacitance when the coupling coefficient is small. Even when the coupling coefficient increases and the filter capacitance decreases, the output phase difference of the inverter of the power transmission device (and thus the output power factor of the inverter) changes. However, since the direction of change is reversed in both cases, the fluctuation in the output phase difference of the inverter accompanying the increase in the coupling coefficient can be canceled (cancelled) by reducing the filter capacitance. For this reason, according to said capacitance control, it becomes easy to make the output phase difference of an inverter small in a wide coupling coefficient range.

  Furthermore, the non-contact power transmission device according to the present disclosure can not only reduce the output phase difference of the inverter as described above, but also the distortion of the output current waveform of the inverter (deviation from the sine wave) as described below. Can also be suppressed.

  When the coupling coefficient increases, the inter-coil efficiency (ratio of received power to transmitted power) between the primary coil and the secondary coil increases. For this reason, when the coupling coefficient increases under the condition that the power supplied to the primary coil (power transmission coil) is constant, the received power also increases. In order to supply the same amount of power to the power receiving apparatus when the coupling coefficient is small and when the coupling coefficient is large, it is necessary to reduce the power supplied to the primary coil when the coupling coefficient is large. It is done. For example, the power supplied to the primary coil can be reduced by reducing the output power of the inverter. In an inverter controlled by pulse width modulation (PWM), the output power of the inverter is reduced by reducing the duty of the output voltage of the inverter.

  However, if the duty of the output voltage of the inverter is made too small, the output current waveform of the inverter is distorted from the sine wave. The closer the output current waveform of the inverter is to a sine wave, the higher the output power factor of the inverter. Therefore, when the output current waveform of the inverter is distorted as described above, the output power factor of the inverter decreases.

  Therefore, the control unit of the non-contact power transmission apparatus according to the present disclosure makes the input DC voltage when the coupling coefficient is large lower than the input DC voltage when the coupling coefficient is small. By reducing the voltage of the DC power input to the inverter (input DC voltage), the output power of the inverter can be reduced without changing the duty of the output voltage of the inverter. For this reason, it is possible to suppress the duty of the output voltage of the inverter from becoming excessively small by controlling the input DC voltage as described above. According to the non-contact power transmission device, distortion of the output current waveform of the inverter (deviation from the sine wave) is suppressed, and the output power factor of the inverter can be easily increased in a wide coupling coefficient range.

  The controller of the non-contact power transmission apparatus may determine whether the coupling coefficient is large or small based on the presence or absence of overcurrent. For example, when a power supply voltage (for example, input DC voltage) and a circuit constant (for example, filter capacitance) are set in accordance with a small coupling coefficient, an overcurrent occurs when the coupling coefficient is large. In particular, when the input DC voltage and the filter capacitance described above do not match the coupling coefficient, at least one of the input current of the inverter, the output current of the inverter, and the current flowing through the primary coil becomes an overcurrent. By monitoring the presence or absence of such an overcurrent, it can be easily determined whether the coupling coefficient is large or small.

  The non-contact power transmission apparatus may further include a distance measuring sensor that detects a distance between the primary coil and the secondary coil (hereinafter also referred to as “distance between coils”). And said control part may judge whether a coupling coefficient is large or small based on the detection value of a ranging sensor.

  In the non-contact power transmission apparatus, the capacitance adjustment unit includes a capacitor and a switching element (hereinafter also referred to as “C switch”) connected in series to the capacitor as elements connected in parallel to the primary coil. The filter capacitance may be changed depending on the state (ON / OFF) of the C switch.

  The non-contact power transmission device of the present disclosure having the above configuration can construct a non-contact power transmission system together with the power receiving device. In such a non-contact power transmission system, when the predetermined current (for example, the output current of the inverter of the power transmission device) becomes a predetermined value or higher during power transmission under the condition that the input DC voltage and the filter capacitance are in the first state. May stop the current power transmission and change the input DC voltage and the filter capacitance to the second state, and then restart the power transmission. In the above control, the first state and the second state may be interchanged. That is, when a predetermined current becomes a predetermined value or more during power transmission under the condition that the input DC voltage and the filter capacitance are in the second state, the current transmission is stopped and the input DC voltage and the filter capacitance are stopped. The power transmission may be resumed after setting to the first state.

  According to the present disclosure, it is possible to provide a contactless power transmission device that easily increases the output power factor of an inverter in a wide coupling coefficient range.

1 is an overall configuration diagram of a power transmission system to which a contactless power transmission device according to an embodiment of the present disclosure is applied. FIG. 2 is a diagram illustrating a configuration for performing non-contact power transmission between a charging facility and a vehicle in the power transmission system illustrated in FIG. 1. It is the figure which showed an example of the circuit structure of the inverter shown in FIG. It is a figure which shows the switching waveform of the inverter shown in FIG. 2, and each waveform of output voltage Vo and output current Iinv. FIG. 3 is a diagram illustrating an example of a circuit configuration of the AC / DC converter illustrated in FIG. 2. 2 is a flowchart showing a charging control processing procedure executed by a vehicle control device in the power transmission system shown in FIG. 1. 2 is a flowchart showing a power transmission control processing procedure executed by a control device for a charging facility in the power transmission system shown in FIG. 1. It is a flowchart which shows the process sequence of the duty control shown in FIG. In the power transmission control executed by the non-contact power transmission device according to the embodiment of the present disclosure, the input voltage of the inverter and the power transmission filter in each of the region having the small coupling coefficient (region A) and the region having the large coupling coefficient (region B) FIG. FIG. 3 is a diagram illustrating a relationship between a coupling coefficient and inter-coil efficiency in the power transmission system illustrated in FIG. 2. It is a figure which shows the output waveform of the inverter in 1st conditions (The coupling coefficient: Large, the input voltage of an inverter: Low, the capacitance of a power transmission filter: Small). It is a figure which shows the current waveform and voltage waveform of a power transmission coil (primary coil) in 1st conditions. It is a figure which shows the output waveform of the inverter in 2nd conditions (The coupling coefficient: Large, the input voltage of an inverter: High, the capacitance of a power transmission filter: Small). It is a figure which shows the current waveform and voltage waveform of a power transmission coil (primary coil) in 2nd conditions. In the power transmission system shown in FIG. 2, it is a figure which shows the change of the output power factor of an inverter when the input voltage of an inverter and the capacitance of a power transmission filter are changed in the condition where a coupling coefficient is large. In the power transmission system shown in FIG. 2, it is a figure which shows the change of the power factor of a power transmission coil (primary coil) when the input voltage of an inverter and the capacitance of a power transmission filter are changed in the condition where a coupling coefficient is large. . FIG. 3 is a diagram showing a change in system efficiency when the input voltage of the inverter and the capacitance of the power transmission filter are changed in a state where the coupling coefficient is large in the power transmission system shown in FIG. 2. It is a figure which shows the modification of a capacitance adjustment part. It is a figure which shows the example which made the inductance of the power transmission filter variable.

  Embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted 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 relative to the vehicle, arrow F is “forward”, arrow B is “rear”, arrow U is “up”, arrow D indicates “below”. Hereinafter, the electronic control unit is referred to as “ECU (Electronic Control Unit)”.

  FIG. 1 is an overall configuration diagram of a power transmission system to which a contactless power transmission device according to an embodiment of the present disclosure is applied. The power transmission system 10 includes a charging facility 1 (ground unit) and a vehicle 2.

  The charging facility 1 includes a power transmission unit 100 and an AC power source 700 that supplies power to the power transmission unit 100. The power transmission unit 100 is installed on the ground F10 (for example, the floor 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).

  The vehicle 2 includes a power reception unit 200, a power storage device 300 that is charged by the power received by the power reception unit 200, and a vehicle ECU 500 that controls the power received by the power reception unit 200. The power receiving unit 200 is provided on the lower surface (road surface side) of the power storage device 300 installed on the bottom surface F <b> 20 of the vehicle 2.

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

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

  Hereinafter, the height from the wheel installation surface of the vehicle 2 (that is, the ground surface 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 receiving coil height ΔH of the vehicle 2 matches the minimum ground height of the vehicle 2. The distance between the power transmission coil provided on the surface of the power transmission unit 100 and the power reception coil provided on the surface of the power reception unit 200 (distance between coils ΔG) varies depending on the height of the power reception coil ΔH. As the power receiving coil height ΔH increases, the inter-coil distance ΔG also increases. Further, as the inter-coil distance ΔG increases, the coupling coefficient between the power transmission coil and the power reception coil tends to decrease. The power receiving coil height ΔH differs depending on the vehicle. In a general charging facility and vehicle, the coupling coefficient is 0.05 to 0.5.

  The power transmission coil and the power reception coil are a primary coil 101 and a secondary coil 201 shown in FIG. 2, respectively. FIG. 2 is a diagram illustrating a configuration for performing non-contact power transmission between the charging facility 1 and the 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 power transmission by performing predetermined power conversion processing on power received from AC power supply 700 and transmits the power for power transmission to power receiving unit 200 in a contactless manner. Configured. Then, the power storage device 300 (vehicle battery) is charged with the power received by the power reception unit 200 from the power transmission unit 100.

  The power transmission unit 100 includes a power conversion unit that performs the power conversion process, an LC resonance unit R1 that performs the contactless 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 unit R1 is provided on the output side of the inverter 120, and is configured by connecting a primary coil 101 and a capacitor 102 in series. Hereinafter, the terminal on the primary coil 101 side of the LC resonance unit R1 is referred to as “L terminal”, and the terminal on the capacitor 102 side of the LC resonance unit R1 is referred to as “C terminal”. Further, an electric wire connecting the L terminal of the LC resonance unit R1 and the output terminal T7 of the inverter 120 is “power line PL1”, and an electric wire connecting the C terminal of the LC resonance unit R1 and the output terminal T8 of the inverter 120 is “power line PL2”. Called.

  AC / DC converter 130 rectifies and transforms the power received from AC power supply 700 and outputs it to inverter 120. Although details will be described later, the AC / DC converter 130 according to this embodiment includes an example of the “transformer” according to the present disclosure (the DC / DC converter 132 illustrated in FIG. 5). AC / DC converter 130 boosts the power received from AC power supply 700 to 400 V, for example, and outputs DC power of voltage 400 V to inverter 120.

  The inverter 120 converts input power (more specifically, direct current power) from the AC / DC converter 130 into alternating current power having a predetermined magnitude and frequency by pulse width modulation (PWM) and outputs the alternating current power to the LC resonance unit R1. Configured to do. The output power of the inverter 120 is supplied to the LC resonance unit R1 through the filter circuit F1. In this embodiment, inverter 120 is a voltage source inverter (for example, a single-phase full bridge circuit shown in FIG. 3 described later). 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 constituting inverter 120 is controlled in accordance with a drive signal from power transmission ECU 150.

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

  Although details will be described later, the duty of the output voltage of inverter 120 is also controlled in accordance with a drive signal from 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 capacitance adjustment unit 103 and a coil 104. The capacitance adjusting unit 103 includes capacitors C11a and C11b and a switch Q11 (C switch). The capacitance adjusting unit 103 and the coil 104 form an LC filter that functions as a low-pass filter (more specifically, an L-type LC filter). This LC filter reduces electromagnetic noise.

The capacitance adjusting unit 103 is configured to be able to change the capacitance of the filter circuit F1 (hereinafter also referred to as “filter capacitance C ₁₁ ” or simply “C ₁₁ ”). The capacitance adjuster 103 includes an element (capacitor C11a and C11b, and a switch Q11) connected in parallel to the LC resonance part R1 include, filter capacitance _{C 11} by such devices (and thus, capacitive between the terminals of the LC resonance part R1 The reactance can be changed.

  The capacitor C11a is connected in parallel to the LC resonance unit R1. One end of the capacitor C11a is connected to the power line PL1, and the other end of the capacitor C11a is connected to the power line PL2.

  The capacitor C11b and the switch Q11 are connected in parallel to the LC resonance unit R1 on the LC resonance unit R1 side of the capacitor C11a. The capacitor C11b and the switch Q11 are connected in series with each other. One end of the capacitor C11b is connected to the power line PL2 via the switch Q11, and the other end of the capacitor C11b is connected to the power line PL1.

Filter capacitance _{C 11} by the state (ON / OFF) of the switch Q11 constituting a capacitance adjustment section 103 changes. More specifically, when the capacitances of the capacitors C11a and C11b are represented as C _A and C _B , respectively, C ₁₁ when the switch Q11 is OFF is “C _A ”, and C ₁₁ when the switch Q11 is ON. Becomes “C _A + C _B ”. In this embodiment, an electromagnetic mechanical relay is employed as the switch Q11. Mechanical relays are easy to obtain at low cost compared to semiconductor relays (transistors and the like).

  The LC resonance unit R1 transmits power to the LC resonance unit R2 of the power receiving unit 200 in a non-contact manner through a magnetic field generated around the primary coil 101. Prior to the start of power transmission, the primary coil 101 and the secondary coil 201 are aligned so as to generate an interlinkage magnetic flux. Then, electric power is transmitted from the primary coil 101 to the secondary coil 201 by magnetic resonance. In this embodiment, the LC resonance unit R1 is a series resonance circuit. The Q value of the LC resonance part 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 configured by a microprocessor including, for example, 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), rewritable nonvolatile memory, and the like) that stores programs and the like. In the storage device, in addition to programs, various information (for example, drive frequency f, duty D, AC / DC converter output voltage V _in , ΔPs, threshold value, etc. used in the processing of FIGS. 7 and 8 described later) ) Is stored. Various controls are executed by the arithmetic device executing the program stored in the storage device. The various controls are not limited to processing by software, and can be processed by dedicated hardware (electronic circuit).

  The power transmission ECU 150 according to this embodiment corresponds to an example of a “control unit” according to the present disclosure. That is, the power transmission ECU 150 is configured to control the inverter 120, the AC / DC converter 130, and the capacitance adjustment unit 103. Power transmission ECU 150 controls switching elements included in inverter 120 and AC / DC converter 130 to adjust transmitted power.

  The power transmission unit 100 further includes a voltage sensor 181 and current sensors 182 to 184. Voltage sensor 181 detects an input voltage (input DC voltage) of inverter 120 and outputs the detected value to power transmission ECU 150. Current sensor 182 detects an 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. Note that the power transmission unit 100 may further include a current sensor (not shown) that detects a current in a portion different from the current sensors 182 to 184. 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 coincide. Further, the output current of the filter circuit F1 coincides with the current flowing through the LC resonance unit R1 (primary coil 101 and the like).

  The power transmission unit 100 further includes a communication unit 160. The communication unit 160 is a communication interface for performing wireless communication with the vehicle 2. Communication unit 160 sends information from power transmission ECU 150 to vehicle 2, receives information from vehicle 2, and outputs the information to power transmission ECU 150.

  The power receiving unit 200 includes an LC resonance unit R2, a filter circuit F2, a rectifier circuit 206, and a smoothing capacitor 207.

  The LC resonance unit R2 is configured by connecting a secondary coil 201 and a capacitor 202 in series. The Q value of the LC resonance part R2 is preferably 100 or more. In this embodiment, as the LC resonating units R1 and R2, SS type (primary side: series, secondary side: series) resonance circuits are employed. However, the present invention is not limited to this, and the SP type (primary side: series). Secondary side: parallel), PP system (primary side: parallel, secondary side: parallel), etc. may be adopted.

  The filter circuit F2 includes capacitors 203 and 205 and a coil 204. The capacitors 203 and 205 are connected in parallel to the LC resonance unit R2, and the coil 204 is connected in series to the LC resonance unit R2. The capacitors 203 and 205 and the coil 204 form an LC filter that functions as a low-pass filter (more specifically, a π-type LC filter). This LC filter reduces electromagnetic noise generated during power reception.

  The rectifier circuit 206 rectifies the AC power received by the secondary coil 201 and outputs the rectified power to the power storage device 300 side. The rectifier circuit 206 is configured by a diode bridge circuit composed of, for example, four diodes. 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.

  The power receiving unit 200 further includes current sensors 283 and 284. Current sensor 284 detects a current flowing through LC resonance unit R2 (secondary coil 201 and the like) and outputs the detected value to power transmission ECU 150. Current sensor 283 detects the current flowing through filter circuit F2, 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. Charging relay 400 is ON / OFF controlled by vehicle ECU 500, and is turned on (conductive state) when power storage device 300 is charged by power receiving unit 200.

  The power storage device 300 is a rechargeable DC power source. Power storage device 300 includes, for example, a secondary battery (such as a lithium ion battery or a nickel metal hydride battery). The power storage device 300 stores the electric power supplied from the power receiving unit 200 and supplies the electric power to a vehicle drive device (running motor and its drive circuit) (not shown).

  A monitoring unit 310 that monitors the state of the power storage device 300 is provided for the power storage device 300. 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), etc.) of power storage device 300 based on the output of monitoring unit 310. The SOC indicates the remaining amount of power storage. For example, the ratio of the current power storage amount to the fully charged power storage amount is expressed as 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 device is constituted by a microprocessor including a CPU, for example. The storage device includes a RAM and a storage (such as a ROM or a rewritable nonvolatile memory) that stores programs and the like. Various controls are executed by the arithmetic device executing the program stored in the storage device. Vehicle ECU 500 executes, for example, travel control of vehicle 2 and charge control of power storage device 300. An ON / OFF signal or the like from the vehicle ECU 500 to the charging relay 400 is output from the output port. The various controls are not limited to processing by software, and can be processed by dedicated hardware (electronic circuit).

  The vehicle 2 further includes a communication unit 600. The communication unit 600 is a communication interface for performing wireless communication with the power transmission unit 100. By performing wireless communication between the communication unit 160 of the charging facility 1 and the communication unit 600 of the vehicle 2, information can be exchanged between the power transmission ECU 150 and the vehicle ECU 500.

  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-Q4 and a plurality of free-wheeling diodes D1-D4. Switching elements Q1-Q4 are constituted by, for example, a power semiconductor switching element (IGBT, bipolar transistor, MOSFET, GTO, or the like). The free-wheeling diodes D1 to D4 are connected in parallel (more specifically, in antiparallel) to the switching elements Q1 to Q4, respectively. An AC / DC converter 130 (FIG. 1) is connected to the DC-side input terminals T5 and T6, and a filter circuit F1 (FIG. 1) is connected to the AC-side output terminals T7 and T8.

  A DC voltage output from the AC / DC converter 130 is applied between the input terminals T5 and T6. In FIG. 3, V1 indicates the magnitude of this DC voltage. Switching elements Q1-Q4 are driven by a drive signal from power transmission ECU 150. Then, by the switching operation of the switching elements Q1 to Q4, the output voltage Vo is applied between the output terminals T7 and T8, and the output current Iinv flows (the direction indicated by the arrow in FIG. 3 is positive). FIG. 3 shows, as an example, a state in which the switching elements Q1 and Q4 are ON and the switching elements Q2 and Q3 are OFF, and the output voltage Vo in this case is almost V1 (positive value). .

  FIG. 4 is a diagram illustrating switching waveforms of the inverter 120 and waveforms of the output voltage Vo and the output current Iinv. Hereinafter, the operation of the inverter 120 will be described with reference to FIG. 4 together with FIG. 3 by taking one cycle from time t4 to time 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, each switching element is in the state shown in FIG. The output voltage Vo of the inverter 120 rises from 0 to V1 (positive value).

  Thereafter, at times t5 to t8, the output voltage Vo also changes as the state of each switching element changes as follows. At time t5, when the switching element Q2 is switched from OFF to ON and the switching element Q4 is switched from ON to OFF, the output voltage Vo becomes zero. At time t6, when the switching element Q1 is switched from ON to OFF and the switching element Q3 is switched from OFF to ON, the output voltage Vo becomes −V1 (negative value). At time t7, when the switching element Q2 is switched from ON to OFF and the switching element Q4 is switched from OFF to ON, the output voltage Vo becomes 0 again.

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

  FIG. 4 shows a case where the duty of the output voltage Vo is 0.25. The ratio of the positive voltage output time (t4 to t5) in one cycle (t4 to t8) is 1/4 (= 0.25). Further, 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 Vo increases, the time during which the output voltage Vo is a positive voltage (V1) or a negative voltage (−V1) in one cycle becomes longer. For this reason, the output power of the inverter 120 increases as the duty of the output voltage Vo increases.

  By changing the switching timing of the switching elements Q1 and Q3 and the switching timing of the switching elements Q2 and Q4, the duty of the output voltage Vo can be changed. For example, when the switching timing of the switching elements Q2 and Q4 is advanced with respect to the state shown in FIG. 4, the duty of the output voltage Vo can be made smaller than 0.25 (the minimum value is 0), and the switching element Q2 , Q4 can be delayed to make the duty of the output voltage Vo larger than 0.25 (the maximum value is 0.5).

  By adjusting the duty of the output voltage Vo, the magnitude of the output power of the inverter 120, and hence the magnitude of the transmission power (the power supplied to the LC resonance unit 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 adjust the duty of output voltage Vo to bring the magnitude of the output power of inverter 120 close to the target power (for example, a charging power command value described later).

  FIG. 5 is a diagram showing an example of the circuit configuration of AC / DC converter 130 shown in FIG. Referring to FIG. 5, AC / DC converter 130 includes a rectifier circuit 131 and a DC / DC converter 132 provided on the output side of rectifier circuit 131.

  The rectifier circuit 131 is configured by a diode bridge circuit including four diodes 131a to 131d. The rectifier circuit 131 rectifies AC power input from the AC power source 700 and outputs DC power.

  The DC / DC converter 132 is a boost type DC / DC converter including a choke coil L10, diodes D10 and D13, a switch Q13, and a smoothing capacitor C10. The diode D13 and the switch Q13 are connected in parallel to the rectifier circuit 131 on the output side of the choke coil L10. Switch Q13 is connected in parallel to diode D13 and is chopper-controlled by power transmission ECU 150. As switch Q13, for example, a power semiconductor switching element (IGBT, bipolar transistor, MOSFET, GTO, or the like) can be employed. A diode D10 and a smoothing capacitor C10 are provided on the output side of the diode D13 and the switch Q13.

  In the AC / DC converter 130 shown in FIG. 5, the AC power supply 700 (FIG. 1) is connected to the input terminals T1 and T2 on the AC side, and the inverter 120 (FIG. 1) is connected to the output terminals T3 and T4 on the DC side. Is connected. Switch Q13 is controlled in accordance with a drive signal from power transmission ECU 150. As the duty ratio of the drive signal of the switch Q13 (more specifically, a square wave voltage signal) (the ratio of the time during which the switch Q13 is ON) increases, the output voltage of the AC / DC converter 130 (and thus the inverter 120) (Input voltage) increases. The power transmission ECU 150 can adjust the output voltage (DC voltage magnitude V1) of the AC / DC converter 130 by controlling the switch Q13 to be ON (closed) / OFF (open).

  By the way, in the power transmission system 10, when the output power factor of the inverter 120 (the ratio of the effective power to the apparent power) decreases, the system efficiency decreases. When the output current of the inverter 120 is a sine wave, the output power factor of the inverter 120 is expressed as “λ”, and the output phase difference of the inverter 120 is expressed as “φ”, so that λ and φ are “λ = | cos φ |”. Satisfies the relational expression. The output phase difference φ is expressed with reference to the voltage phase. In other words, the output phase difference is a positive value when the current phase is shifted toward the retarded side with respect to the voltage phase, and the output level is shifted when the current phase is shifted toward the advanced side relative to the voltage phase. The phase difference is negative. For example, if the output phase difference is 0 ° (no phase difference), the output power factor of the inverter 120 is 1 (active power only). As the output phase difference increases, the output power factor of the inverter 120 tends to decrease (that is, the reactive power increases).

In this embodiment, at the initial stage (for example, at the time of initialization in the process of FIG. 7 described later), when the coupling coefficient is small (for example, when the coupling coefficient is 0.05 to 0.3), the output of inverter 120 circuit constants (the filter capacitance C _11, etc.) is set so that the phase difference becomes smaller. Thereby, when the coupling coefficient is small, the output phase difference of the inverter 120 is sufficiently small. However, when the coupling coefficient is increased (e.g., when the coupling coefficient becomes about 0.5), maintaining circuit constant (filter capacitance C _11, etc.) to the value obtained when the coupling coefficient is small, the inverter 120 The output phase difference increases.

Therefore, power transmission ECU150 is the filter capacitance _{C 11} when the coupling coefficient is large, smaller than the filter capacitance _{C 11} when the coupling coefficient is small. If the coupling coefficient is larger, if the filter capacitance C ₁₁ becomes smaller, the output phase difference of the inverter 120 is changed. However, since the direction of change is reversed in both can be offset by reducing the filter capacitance C _11, the variation of the output phase difference of the inverter 120 due to the coupling coefficient is increased. For this reason, according to said capacitance control, it becomes easy to make the output power factor of the inverter 120 high in a wide coupling coefficient range by making the output phase difference of the inverter 120 small.

  Furthermore, the power transmission unit 100 according to this embodiment not only can reduce the output phase difference of the inverter 120 as described above, but also can be distorted (sinusoidal) in the output current waveform of the inverter 120 as described below. Can also be suppressed.

  When the coupling coefficient increases, the inter-coil efficiency of the primary coil 101 and the secondary coil 201 increases. For this reason, when the coupling coefficient increases under the condition that the power supplied to the primary coil 101 is constant, the received power also increases. In order to supply the same amount of power to the power receiving unit 200 when the coupling coefficient is small and when the coupling coefficient is large, the power supplied to the primary coil 101 is reduced when the coupling coefficient is large. Is required. For example, by reducing the output power of the inverter 120, the power supplied to the primary coil 101 can be reduced. In inverter 120 controlled by pulse width modulation (PWM), the output power of inverter 120 is reduced by reducing the duty of output voltage Vo (FIG. 4) of inverter 120.

  However, if the duty of the output voltage Vo of the inverter 120 is made too small, the output current waveform of the inverter 120 is distorted from the sine wave. As the output current waveform of the inverter 120 is closer to a sine wave, the output power factor of the inverter 120 becomes higher. Therefore, when the output current waveform of the inverter 120 is distorted as described above, the output power factor of the inverter 120 is lowered.

  Therefore, power transmission ECU 150 makes the input voltage of inverter 120 when the coupling coefficient is large lower than the input voltage of inverter 120 when the coupling coefficient is small. By reducing the input voltage of the inverter 120, the output power of the inverter 120 can be reduced without changing the duty of the output voltage Vo of the inverter 120 (and the drive frequency of the inverter 120 is also constant). For this reason, it is possible to suppress the duty of the output voltage Vo of the inverter 120 from becoming excessively small by controlling the input voltage (input DC voltage) of the inverter 120 as described above. Thus, according to the power transmission unit 100, distortion of the output current waveform of the inverter 120 (deviation from the sine wave) is suppressed, and the output power factor of the inverter 120 can be easily increased in a wide coupling coefficient range.

In this embodiment, the DC / DC converter 132 (transformer unit) shown in FIG. 5 is configured to be able to change the voltage of the DC power input to the inverter 120, so that the power transmission ECU 150 includes the DC / DC converter 132. By controlling, the input voltage of the inverter 120 is adjusted. The storage device of the power transmission ECU 150 stores an AC / DC converter output voltage V _in (hereinafter simply referred to as “AC / DC converter 130 drive condition” (more specifically, the duty ratio of the drive signal of the switch Q13 shown in FIG. 5)). (Also referred to as “V _in ”). When the value in the AC / DC converter output voltage _{V in} is set, the AC / DC converter 130 (more specifically at the duty ratio as the output voltage of the AC / DC converter 130 becomes the value shown in FIG. 5 The switch Q13) is driven. In this embodiment, since the input voltage of the output voltage and the inverter 120 of the AC / DC converter 130 is matched, by the drive of the AC / DC converter 130 is adjusted so that the input voltage of the inverter 120 is equal to _{V in} The

Transmission ECU150 determines whether the coupling coefficient between the primary coil 101 and secondary coil 201 is large or small, and the _{C 11} and _{V in} the first state when the coupling coefficient is small, when the coupling coefficient is large Is configured to place C ₁₁ and V _in in the second state. Hereinafter, C ₁₁ and V _in in the first state are referred to as “C _H ” and “V _H ”, respectively. Also, C ₁₁ and V _in in the second state are referred to as “C _L ” and “V _L ”, respectively. C _H is larger than C _L and V _H is higher than V _L.

Each of C _H and V _H is obtained in advance by experiments or the like, and when the coupling coefficient is small (for example, when the coupling coefficient is 0.05 or more and 0.30 or less), the output power factor of inverter 120 is sufficiently high. It is set to such a value. Each of C _L and V _L is obtained in advance by experiments or the like, and when the coupling coefficient is large (for example, when the coupling coefficient is 0.25 or more and 0.60 or less), the output power factor of inverter 120 is sufficiently high. It is set to such a value. In this embodiment, C ₁₁ becomes C _H (= C _A + C _B ) when the switch Q 11 is turned on, and C ₁₁ becomes C _L (= C _A ) when the switch Q 11 is turned off.

  Next, an example of a processing procedure in the case where the above-described control is incorporated in the non-contact power transmission control and the power storage device 300 of the vehicle 2 is charged by the charging facility 1 will be described.

  First, the driver stops the vehicle 2 in the charging space of the charging facility 1. Then, after establishing a communication connection (for example, connection to a wireless LAN) between the vehicle ECU 500 and the power transmission ECU 150 at the stop position of the vehicle 2, a power transmission request is sent from the vehicle ECU 500 to the 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, charging information (information indicating the specifications of charging facility 1) and vehicle information (information indicating the specifications of vehicle 2) are collated between power transmission ECU 150 and vehicle ECU 500. It is determined whether or not the vehicle 2 can be charged by the charging facility 1 based on the result of this collation. More specifically, the vehicle information includes, for example, the vehicle type (or identification number) of the vehicle 2, the rated voltage of the power storage device 300, and the like. Further, the charging information includes, for example, power supplied to the charging facility 1 and a maximum output voltage. When the specification of the vehicle 2 corresponds to the specification of the charging facility 1, the power transmission ECU 150 and the vehicle ECU 500 determine that the vehicle 2 can be charged by the charging facility 1 (chargeable), and prepare for the power transmission preparation described below. move on. On the other hand, when the specifications of vehicle 2 do not correspond to the specifications of charging equipment 1 (for example, when the maximum output voltage of charging equipment 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 that charging is possible by the above collation, the power transmission ECU 150 starts preparation for power transmission. The power transmission preparation is a process for setting the power transmission system 10 in a state where power can be transmitted. For example, alignment between the power transmission unit 100 and the power reception unit 200 is performed as the power transmission preparation. When charging facility 1 includes a plurality of power transmission units, a process (so-called pairing) for specifying which power transmission unit is aligned may be performed as the power transmission preparation. . Various methods are known as alignment and pairing methods, and any method can be adopted.

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

  FIG. 6 is a flowchart showing a charging control processing procedure executed by vehicle ECU 500 after the above collation and power transmission preparation are completed. The processing shown in this flowchart includes steps S11 to S17, S21, S22, and S30 (hereinafter simply referred to as “S11” to “S17”, “S21”, “S22”, and “S30”).

  Referring to FIG. 6, vehicle ECU 500 performs initialization (S11). For example, the vehicle ECU 500 initializes error information stored in the storage device, although the content of the initialization process is arbitrary. Initially, the error information indicates that no abnormality has occurred.

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

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

  Note that the method for determining the presence or absence of abnormality is arbitrary. For example, vehicle ECU 500 may determine that an abnormality has occurred 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 S14. 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, for example, and the calculated value obtained. Is stored in a storage device. More specifically, vehicle ECU 500 decreases charge power command value Ps as the SOC of power storage device 300 approaches full charge (100%). Note that the SOC measurement method is arbitrary, and a method based on current value integration (Coulomb count), a method based on estimation of an open circuit voltage (OCV), or the like can be employed.

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

In S <b> 21, vehicle ECU 500 controls communication unit 600 to transmit information to power transmission unit 100. Predetermined information (for example, Ps and P _out ) is transmitted from the communication unit 600 toward the power transmission unit 100. The information transmitted from the communication unit 600 is received by the communication unit 160 in the power transmission unit 100.

  In S16, vehicle ECU 500 determines whether or not charging is completed. For example, vehicle ECU 500 determines that charging is completed 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 the vehicle ECU 500 or the like, or may be set by the user.

  In this embodiment, it is assumed that 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 completion condition can be arbitrarily set. For example, the completion condition may be satisfied when the charging time (elapsed time from when charging is started) becomes longer than a predetermined value. Further, the completion condition may be satisfied when the user gives an instruction to stop charging during charging.

  If charging has not been completed (NO in S16), the process returns to S13. Loop processing S13 to S16 is repeatedly executed until it is determined that charging has been completed in S16 (YES in S16) or an abnormality has occurred in S13 (YES in S13).

  If YES is determined in any of S13 and S16, a charge stop process (S22 and S17) described below is performed. However, if YES is determined in S13, after the process of S30, the charge stop process (S22 and S17) is forcibly performed without waiting for the completion of the charge. In S30, vehicle ECU 500 updates 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 stopping the charging, it is possible to know whether the charging has been normally completed and stopped, or whether the charging has been forcibly performed due to an abnormality during the charging.

  In S <b> 22, vehicle ECU 500 controls communication unit 600 to send information to power transmission unit 100. Predetermined information (for example, a power transmission stop request and error information) is transmitted from the communication unit 600 to the power transmission unit 100. The information transmitted from the communication unit 600 is received by the communication unit 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 interrupted, and power supply to power storage device 300 (and thus charging of power storage device 300) is not performed. With this S17, the processing of FIG. 6 ends.

  FIG. 7 is a flowchart showing a power transmission control processing procedure executed by 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. 7, power transmission ECU 150 initializes (S51). More specifically, the power transmission ECU150 is, then the switch Q11 ON, the filter capacitance _{C 11} to _{C H} (initial value). Further, the power transmission ECU150 is driving condition of the AC / DC converter 130 (more specifically, the duty ratio of the drive signal of the switch Q13 shown in FIG. 5) _{V H} (initial value AC / DC converter output voltage _{V in} showing the ) Is set. Further, the power transmission ECU 150 sets 0 (initial value) to ΔPs used in S55 and S56 described later and S76 in FIG.

  Subsequently, power transmission ECU 150 sets a predetermined minimum value as drive frequency f in the drive signal of 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. 8 is a flowchart showing the processing procedure of this duty control. The processes shown in this flowchart are steps S71 to S78, S81 to S85, S91, and S92 (hereinafter simply referred to as “S71” to “S78”, “S81” to “S85”, “S91”, and “S92”). including.

  Referring to FIG. 8, 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 set to 0.15.

  Next, the power transmission ECU 150 determines whether or not a power transmission stop request (S22 in FIG. 6) has been received from the vehicle 2 (S72). If it is determined that a power transmission stop request has not been received (NO in S72), power transmission ECU 150 determines whether an abnormality has occurred on the power transmission side (S73). The determination method of the presence or absence of 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.

If 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). The power transmission ECU 150 determines that the output voltage (DC voltage) of the AC / DC converter 130 is the AC / DC converter output voltage V _in (V _H or V _L ) set in S51 of FIG. 7 or S84 of FIG. / DC converter 130 (more specifically, switch Q13 shown in FIG. 5) is controlled. Transmission ECU150 _determines the duty ratio of the drive signal for the switch Q13 in response to _{V in.} 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. 7 and S71 or S77 of FIG. As the drive frequency f, the minimum value set in S52 of FIG. 7 is used initially, but when the process of S53 of FIG. 7 described later is performed, the value set in S53 is used. Further, the duty D of the output voltage initially becomes the minimum value set in S71, but increases by a predetermined amount every time the process of S77 described later is executed.

  In S75, power transmission ECU 150 determines whether the current (predetermined current to be monitored) of each part of power transmission unit 100 is within a predetermined allowable range. The current to be monitored can be arbitrarily set, but includes at least first to third monitoring currents described later. If at least one of the currents in each part of the power transmission unit 100 is not within the allowable range (for example, if an overcurrent has occurred), NO is determined in S75, and all the currents in each part of the power transmission unit 100 are within the allowable range. If YES, YES is determined in S75.

  When it is determined NO in S75, it is determined whether or not the predetermined current exceeds the allowable range (S81). In this embodiment, as the predetermined current, the output current of the AC / DC converter 130 detected by the current sensor 182 (hereinafter also referred to as “first monitoring current”) and the inverter detected by the current sensor 183. The output current of 120 (hereinafter also referred to as “second monitoring current”) and the current flowing through the LC resonance unit R1 detected by the current sensor 184 (hereinafter also referred to as “third monitoring current”) are employed. . In S81, power transmission ECU 150 determines whether at least one of the first to third monitoring currents is equal to or greater than a predetermined threshold value. A different threshold may be used for each current.

In this embodiment, initially, the circuit constant (C ₁₁ ) of the power transmission unit 100 and the drive condition (V _in ) of the AC / DC converter 130 are set so as to match a small coupling coefficient (reference coupling coefficient). Yes. For this reason, when the coupling coefficient is large (for example, when the inter-coil distance ΔG is small), the difference between the coupling coefficient and the reference coupling coefficient is large, and at least one of the first to third monitoring currents due to impedance mismatching. One becomes excessively large. By monitoring the presence or absence of such an overcurrent, it can be easily determined whether the coupling coefficient is large or small.

A determination of YES in S81 (that at least one of the first to third monitoring currents is equal to or greater than the threshold value) means that the coupling coefficient is large. In this case, since it is considered that an overcurrent has occurred due to a large coupling coefficient (that is, the coupling coefficient greatly deviates from the reference coupling coefficient), C ₁₁ and V _in are adjusted to the large coupling coefficient. By changing, overcurrent does not occur.

If YES is determined in S81, in S82, the power transmission ECU 150 stops the power transmission by stopping the inverter 120 and the AC / DC converter 130 (non-driving state). Subsequently, in S83, the power transmission ECU150 is, then the switch Q11 OFF, the filter capacitance _{C 11} (the value smaller than _{C H) C} L. Further, in S84, the power transmission ECU150 sets the (lower than _{V H) V} L to the AC / DC converter output voltage _{V in.} By thus C ₁₁ and V _in is changed, C ₁₁ and V _in is, the value matching the large coupling coefficient, overcurrent as described above will not occur. If an overcurrent occurs again after the processing of S83 and S84 (YES in S81), it is considered not normal, so it is determined that an abnormality has occurred, and power transmission stop processing (S91 and S92 described later) is determined. ) May be performed.

  Subsequently, the power transmission ECU 150 drives the inverter 120 and the AC / DC converter 130 to resume power transmission from the primary coil 101 to the secondary coil 201 (S85). Thereafter, the process returns to S72.

  On the other hand, determining NO in S81 means that an overcurrent has occurred due to a factor other than the coupling coefficient. If it is determined NO in S81, it is highly possible that the drive frequency f is not matched. Therefore, the process is returned to the main routine (the process of FIG. 7), and duty control at the current drive frequency f is performed. finish. The process proceeds to S53 in FIG.

If all of the components of the current in the transmitting unit 100 is within the allowable range (YES in S75), the transmission ECU150 is whether the deviation between the charging power command value Ps and the actual charging power _{P out} is sufficiently small Judgment is made (S76).

  Charging power command value Ps is generated in vehicle ECU 500 (see S14 in FIG. 6) and transmitted from vehicle 2 to power transmission unit 100 (see S21 in FIG. 6). When ΔPs is 0 (initial value) (see S51 in FIG. 7), power transmission ECU 150 uses the value received from vehicle 2 as it is as charging power command value Ps in S76. On the other hand, when the process of S55 of FIG. 7 described later is performed, ΔPs becomes a value larger than 0, and charging power command value Ps is corrected by ΔPs. 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.

The actual charging power P _out is generated in the vehicle ECU 500 (see S15 in FIG. 6) and transmitted from the vehicle 2 to the power transmission unit 100 (see S21 in FIG. 6). Transmission ECU150, in S76, using the values received from the vehicle 2 as it is as the 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 greater the difference (absolute value), the greater the deviation. Also, the closer the ratio is to 1, the smaller the deviation. In this embodiment, in S76, the difference between the Ps and _{P out (| Ps-P out} |) is a predetermined threshold Th1 (hereinafter, simply referred to as "Th1") or not less either, transmission ECU 150 determines.

When it is determined NO in S76 (when | Ps−P _out | is greater than Th1), power transmission ECU 150 sets duty D of the output voltage in the drive signal of inverter 120 by unit operation amount ΔD from the current value. Increase (S77). Subsequently, the power transmission ECU 150 determines whether the duty D is equal to or less than a predetermined threshold value Th2 (hereinafter also simply referred to as “Th2”) (S78). Th2 corresponds to the maximum value of the duty D. In this embodiment, Th2 (the maximum value of duty D) is set to 0.35. If duty D does not become larger than Th2 even after the process of S77 (YES in S78), the process returns to S72.

Also, if it is determined YES in S76, the process returns to S72. A determination of YES in S76 indicates that there is a duty D in which | Ps−P _out | is equal to or less than Th1 in a range (0.15 to 0.35) of the duty D from the minimum value to the maximum value. 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, a power transmission stop request is received from vehicle 2 (YES in S72), or 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.

In addition, when NO is determined in S78 (duty D is greater than Th2), the range from the minimum value to the maximum value of duty D (0.15 to 0.35) becomes | Ps−P _This means that there is no duty D at which _out | becomes equal to or less than Th1. If NO is determined in S78, the process returns to the main routine (the process of FIG. 7), and the duty control at the current drive frequency f ends. The process proceeds to S53 in FIG.

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

  In S91, power transmission ECU 150 stops inverter 120 and AC / DC converter 130 in a stopped state (non-driving state) to stop power transmission. In S <b> 92, power transmission ECU 150 controls communication unit 160 to send information to vehicle 2. Predetermined information (for example, a power transmission stop notification indicating that power transmission stop has been completed) is transmitted from the communication unit 160 toward the vehicle 2. When power transmission stops due to the occurrence of an abnormality (YES in S73), an abnormality occurrence notification indicating that an abnormality has occurred may be transmitted from the communication unit 160 to the vehicle 2. The information transmitted from the communication unit 160 is received by the communication unit 600 in the vehicle 2. With this S92, not only the processing of FIG. 8 but also the processing of FIG. 7 (power transmission control by the power transmission ECU 150) is completed.

  Referring to FIG. 7 again, if NO is determined in any of S78 and S81 in FIG. 8, the process proceeds to S53. In S53, power transmission ECU 150 increases drive frequency f in the drive signal of inverter 120 by unit operation amount Δf from the current value. Subsequently, the power transmission ECU 150 determines whether or not the drive frequency f is less than a predetermined threshold value Th3 (hereinafter also simply referred to as “Th3”) (S54). In this embodiment, Th3 (upper limit value of the driving frequency f) is 90.0 kHz. If drive frequency f does not become equal to or higher than Th3 even after the process of S53 (YES in S54), the above-described duty control (process of FIG. 8) is executed at the drive frequency f (S62).

When NO is determined in S54 (the drive frequency f is equal to or greater than Th3), the duty control (duty adjustment range: 0.15 to 0.35) is performed while changing the drive frequency f. This means that there is no drive frequency f at which | Ps−P _out | is equal to or less than Th1 in the adjustment range (81.4 kHz to 90.0 kHz) of the drive frequency f (see S76 in FIG. 8). If NO is determined in S54, the process proceeds to S55.

  In S55, power transmission ECU 150 decreases charge power command value Ps by increasing ΔPs indicating a correction amount (more specifically, a decrease amount) of charge 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. 8, the charging power command value Ps received from the vehicle 2 is subtracted and corrected (Ps−ΔPs) by ΔPs. As ΔPs increases, the corrected Ps decreases. 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 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 equal to or greater than Th4 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 equal to or greater than Th4), even if the charge power command value Ps is decreased within the adjustment range of ΔPs (0 to Th4), | Ps−P _out | becomes equal to or less than Th1. (See S76 in FIG. 8). 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. That is, in S57, power transmission ECU 150 stops inverter 120 and AC / DC converter 130 in a stopped state (non-driving state) to stop power transmission. In S <b> 58, power transmission ECU 150 controls communication unit 160 to transmit information toward vehicle 2. With this S58, the processing of FIG. 7 (power transmission control by the power transmission ECU 150) ends.

As described above, the power transmission ECU150 according to this embodiment, (S81 in FIG. 8) determines whether the coupling coefficient is large or small, when the coupling coefficient is _small, the _{C 11} and _{V in} the first In the state (C _H , V _H ), when the coupling coefficient is large, C ₁₁ and V _in are configured to be in the second state (C _L , V _L ). In this embodiment, V _in is equivalent to the DC power of the voltage input to the inverter 120 (input DC voltage). If the coupling coefficient is large (in S81 of FIG. 8 YES) to the _{C 11} and _{V in} the first state _{(C H, V} H) from the second state _{(C L, V} L) is changed to (FIG. 8 S83 and S84) can suppress both the increase in the output phase difference of the inverter 120 and the distortion (deviation from the sine wave) of the output current waveform of the inverter 120. By performing such control, it becomes easy to increase the output power factor of the inverter 120 in a wide coupling coefficient range.

  In the process of FIG. 8, the power transmission ECU 150 determines whether the coupling coefficient between the primary coil 101 and the secondary coil 201 is large or small based on the presence or absence of overcurrent. By monitoring the presence or absence of overcurrent for a given current, the coupling coefficient can be easily detected. The fact that no overcurrent occurs means that the coupling coefficient is small.

Note that to calculate the coupling coefficient in real time from the detection values of various sensors, it is conceivable to precisely control the C ₁₁ and V _in accordance with the calculated coupling coefficient. However, it is difficult to calculate the coupling coefficient with high accuracy, and even if the coupling coefficient can be calculated with high accuracy, the control becomes complicated and processing delays are likely to occur.

In the process of FIG _{8, C 11} and _{V in} the first state _(C H, _{V H)} of predetermined during transmission of the condition is a current (e.g., first to third monitoring current) exceeds a predetermined value in a case where it becomes more (YES at S81 in FIG. 8), to stop the transmission in progress (S82 in FIG. _8), the _{C 11} and _{V in} a second state _(C L, _{V L)} in (S83 and S84 in FIG. 8), power transmission is resumed (S85 in FIG. 8). Such a control does not require a semiconductor relay having a high response speed as the switch Q11, and a mechanical relay that is easily available at a lower cost than the semiconductor relay can be used. However, the type of the switch Q11 is not limited to the mechanical relay. A semiconductor relay may be employed instead of the mechanical relay.

FIG. 9 shows the input voltage (input DC voltage) of the inverter 120 and the power transmission filter in each of the region where the coupling coefficient is small (region A) and the region where the coupling coefficient is large (region B) in the power transmission control according to this embodiment. is a diagram showing capacitance (filter capacitance _{C 11).}

Referring to FIG. 9, the power transmission control according to this embodiment, in the region A coupling coefficient in the range of the coupling coefficient k1~k2 is less than Kx, the input voltage of the inverter 120, the filter capacitance C ₁₁ each V _H , the _{C H.} Further, in the region B coupling coefficient in the range of the coupling coefficient k1~k2 is above Kx, the input voltage of the inverter 120, the filter capacitance _{C 11} is _C L, _{V L,} respectively. The range of the coupling coefficients k1 to k2 is, for example, about 0.1 to about 0.6, and Kx is, for example, about 0.3.

  FIG. 10 is a diagram showing the relationship between the coupling coefficient and the inter-coil efficiency in the power transmission system 10 according to this embodiment. Referring to FIG. 10, in the range of coupling coefficients k1 to k2 (for example, about 0.1 to about 0.6), the inter-coil efficiency of primary coil 101 and secondary coil 201 increases as the coupling coefficient increases. Get higher.

  FIG. 11 is a diagram illustrating an output waveform of the inverter 120 under the first condition. FIG. 12 is a diagram illustrating a current waveform and a voltage waveform of the power transmission coil (primary coil 101) under the first condition. In FIG. 11, the line k11 indicates the output voltage waveform of the inverter 120, and the line k12 indicates the output current waveform of the inverter 120. In FIG. 12, the line k13 shows the voltage waveform of the primary coil 101, and the line k14 shows the current waveform of the primary coil 101.

The first condition is a coupling coefficient k2 (approximately 0.6), the input voltage of the inverter 120 is the _{V L,} a condition filter capacitance _{C 11} is _{C L.} Since the coupling coefficient is large, the inter-coil efficiency is increased (see FIG. 10). For this reason, it is required to reduce the power supplied to the primary coil 101. 11 and 12, since the input voltage of inverter 120 is low, the duty of the output voltage of inverter 120 is relatively large (see line k11). With such a voltage waveform, the output current waveform of the inverter 120 is a waveform close to a sine wave (see line k12). Since the output current waveform of the inverter 120 is close to a sine wave, the output power factor of the inverter 120 is increased, and furthermore, the power factor of the power transmission coil (primary coil 101) is also increased (see lines k13 and k14).

  FIG. 13 is a diagram illustrating an output waveform of the inverter 120 under the second condition. FIG. 14 is a diagram illustrating a current waveform and a voltage waveform of the power transmission coil (primary coil 101) under the second condition. In FIG. 13, a line k21 indicates the output voltage waveform of the inverter 120, and a line k22 indicates the output current waveform of the inverter 120. In FIG. 14, the line k23 indicates the voltage waveform of the primary coil 101, and the line k24 indicates the current waveform of the primary coil 101.

The second condition is a coupling coefficient k2 (approximately 0.6), the input voltage of the inverter 120 is the _{V H,} a condition filter capacitance _{C 11} is _{C L.} Since the coupling coefficient is large, the inter-coil efficiency is increased (see FIG. 10). For this reason, it is required to reduce the power supplied to the primary coil 101. Referring to FIGS. 13 and 14, since the input voltage of inverter 120 is high, the duty of the output voltage of inverter 120 is smaller than the first condition (see line k11 in FIG. 11) (line k21). reference). Due to such a voltage waveform, the output current waveform of the inverter 120 is distorted from the sine wave (see the line k22). Due to the distortion of the output current waveform of the inverter 120 (deviation from the sine wave), the output power factor of the inverter 120 is lowered, and further, the power factor of the power transmission coil (primary coil 101) is also lowered (line). k23 and k24).

  As understood from FIGS. 11 to 14, by making the input voltage of the inverter 120 when the coupling coefficient is large lower than the input voltage of the inverter 120 when the coupling coefficient is small, the output current waveform of the inverter 120 is reduced. Distortion (deviation from a sine wave) can be suppressed.

FIG. 15 shows the input voltage (V _in ) and power transmission of the inverter 120 in a situation where the coupling coefficient is large (more specifically, a situation where the coupling coefficient is about 0.6) in the power transmission system 10 shown in FIG. is a diagram showing changes in output power factor of the inverter 120 when changing the filter capacitance (C _11). As shown in FIG. 15, in a situation where the coupling coefficient is large, the output power factor of the inverter 120 is higher in the third state (C _L , V _H ) than in the first state (C _H , V _H ). Thus, the output power factor of the inverter 120 is higher in the second state (C _L , V _L ) than in the third state (C _L , V _H ).

FIG. 16 shows the input voltage (V _in ) and power transmission of the inverter 120 in the power transmission system 10 shown in FIG. 2 in a situation where the coupling coefficient is large (more specifically, a situation where the coupling coefficient is about 0.6). is a graph showing changes in the power factor of the power transmission coil (primary coil 101) when changing the filter capacitance (C _11). As shown in FIG. 16, in a situation where the coupling coefficient is large, the power factor of the primary coil 101 is higher in the third state (C _L , V _H ) than in the first state (C _H , V _H ). The power factor of the primary coil 101 was higher in the second state (C _L , V _L ) than in the third state (C _L , V _H ).

FIG. 17 shows the input voltage (V _in ) and power transmission of the inverter 120 in a situation where the coupling coefficient is large (more specifically, a situation where the coupling coefficient is about 0.6) in the power transmission system 10 shown in FIG. it is a graph showing changes in system efficiency when changing the filter capacitance (C _11). As shown in FIG. 17, in a situation where the coupling coefficient is large, the system efficiency is higher in the third state (C _L , V _H ) than in the first state (C _H , V _H ). The system efficiency is higher in the second state (C _L , V _L ) than in the state (C _L , V _H ).

As described above, in the power transmission system 10 according to this embodiment, when the coupling coefficient is large, the output of the inverter 120 is obtained by setting C ₁₁ and V _in to the second state (C _L , V _L ). The power factor (as a result, the power factor of the primary coil 101) increases, and the system efficiency also increases.

In the above embodiment, the initial values of C ₁₁ and V _in are set to the first state (C _H , V _H ), but the initial values of C ₁₁ and V _in are set to the second state (C _L , V _L). ). The initial value of the second state of the C ₁₁ and _{V in (C L, V L} ) when the overcurrent is not generated when the coupling coefficient is large, an overcurrent occurs when the coupling coefficient is small. The presence or absence of such an overcurrent is monitored, and when an overcurrent occurs (that is, when the coupling coefficient is small), C ₁₁ and V _in are changed from the second state (C _L , V _L ) to the first state ( By changing to C _H , V _H ), it becomes easy to ensure a sufficient output power factor of the inverter 120 in a wide coupling coefficient range.

  The circuit configuration of the power transmission system 10 is not limited to the configuration illustrated in FIG. For example, the LC resonance units R1 and R2 are not limited to the series resonance circuit shown in FIG. At least one of the LC resonance units R1 and R2 may be configured by connecting a coil and a capacitor in parallel. Further, the LC filter of the power transmission unit 100 is not limited to the L-type LC filter illustrated in FIG. 2, and other types of LC filters (for example, T in which an inductor is added to the output side of the capacitance adjustment unit 103 illustrated in FIG. 2). Type LC filter).

  The configuration of the capacitance adjustment unit configured to be able to change the capacitance of the LC filter of the power transmission unit 100 is not limited to the configuration illustrated in FIG. FIG. 18 is a diagram illustrating a modification of the capacitance adjustment unit. Referring to FIG. 18, in this example, a variable capacitor C <b> 11 c is employed instead of the capacitance adjustment unit 103. The variable capacitor C11c is configured such that the capacitance changes continuously according to a control signal from the power transmission ECU 150. As the variable capacitor C11c, for example, an air gap capacitor using air as a dielectric can be employed. Note that the present invention is not limited to this variable capacitor, and an arbitrary variable capacitor can be selected from various known variable capacitors.

  The LC filter (power transmission filter) of the power transmission unit 100 may include an inductance adjusting unit configured to change the inductance. FIG. 19 is a diagram illustrating an example in which the inductance of the power transmission filter is variable. Referring to FIG. 19, in this example, a variable inductor L <b> 11 is employed instead of the coil 104, and a variable capacitor C <b> 11 c is employed instead of the capacitance adjustment unit 103. The variable inductor L11 corresponds to the inductance adjusting unit. The variable inductor L11 includes, for example, a magnetic body (core) and an excitation winding, and is configured such that the inductance is continuously changed according to a control signal from the power transmission ECU 150 (more specifically, the current of the excitation winding). Is done. The inductance of the variable inductor L11 can be adjusted to an arbitrary value by flowing a DC superimposed current through the exciting winding to change the magnetic permeability. Note that the present invention is not limited to this variable inductor, and any variable inductor can be selected from various known variable inductors.

  The method for determining whether the coupling coefficient is large or small can be arbitrarily changed. For example, the power transmission unit 100 may further include a distance measuring sensor that detects the inter-coil distance ΔG (FIG. 1). As the distance measuring sensor, an ultrasonic sensor, a laser distance measuring sensor, or the like can be adopted. The power transmission ECU 150 may determine whether the coupling coefficient is large or small based on the detection value of the distance measuring sensor. Since the coupling coefficient decreases as the inter-coil distance ΔG increases, the power transmission ECU 150 determines that the coupling coefficient is large when the inter-coil distance ΔG is smaller than a predetermined value, and when the inter-coil distance ΔG is larger than the predetermined value. It can be determined that the coupling coefficient is small.

  The processes in FIGS. 6 to 8 are examples of power transmission / reception control, and are not limited thereto. For example, after performing an extreme value search of the drive frequency of the inverter 120 (search for a frequency at which power loss is minimized), the duty of the output voltage of the inverter 120 is adjusted to an optimum value at the searched frequency (extreme value). Also good.

  The device to which power is supplied from the power receiving unit 200 is not limited to the power storage device 300, and may be any electric load (such as an in-vehicle device).

Each of the above modifications may be implemented by combining all or some of them.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiment but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  DESCRIPTION OF SYMBOLS 1 Charging equipment, 2 Vehicle, 10 Power transmission system, 100 Power transmission unit, 101 Primary coil, 102, 202, 203, 205, 207 Capacitor, 103 Capacitance adjustment part, 104, 204 coil, 120 Inverter, 130 AC / DC converter , 131 rectifier circuit, 131a to 131d diode, 132 DC / DC converter, 140 power monitoring unit, 150 power transmission ECU, 160,600 communication unit, 181 voltage sensor, 182, 183, 184, 283, 284 current sensor, 200 power receiving unit , 201 secondary coil, 206 rectifier circuit, 300 power storage device, 310 monitoring unit, 400 charging relay, 500 vehicle ECU, 700 AC power supply, C10, C11a, C11b capacitor, C11c variable capacitor Sita, D1 to D4 freewheeling diode, D10, D13 diodes, F1, F2 filtering circuit, L10 choke coil, L11 variable inductor, Q1 to Q4 switching elements, Q11, Q13 switches, R1, R2 LC resonance part.

Claims (1)

A non-contact power transmission device that transmits power from a primary coil to a secondary coil of a power receiving device in a non-contact manner,
An inverter that converts DC power into AC power having a predetermined magnitude and frequency by pulse width modulation and outputs the AC power;
A transformer configured to be able to change the voltage of the DC power input to the inverter;
An LC resonance unit which is provided on the output side of the inverter and is configured by connecting the primary coil and the capacitor in series or in parallel;
An LC filter provided between the inverter and the LC resonance unit;
The LC filter includes a capacitance adjusting unit configured to change the capacitance,
The non-contact power transmission device further includes a control unit that controls the inverter, the transformer unit, and the capacitance adjustment unit,
The control unit determines whether a coupling coefficient between the primary coil and the secondary coil is large or small, and when the coupling coefficient is small, sets the voltage of the DC power and the capacitance of the LC filter to the first. When the coupling coefficient is large, the voltage of the DC power and the capacitance of the LC filter are configured to be in the second state,
The contactless power transmission device in which the voltage of the DC power is lower and the capacitance of the LC filter is smaller in the second state than in the first state.

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