JP6974244B2 - Contactless power transmission device - Google Patents

Description

The present disclosure relates to a non-contact power transmission device, and more particularly to a non-contact power transmission device for non-contact power transmission from a power transmission coil to a power receiving coil of a power receiving device.

A non-contact power transmission system for transmitting power from a power transmission coil of a power transmission device to a power reception coil of a power receiving device in a non-contact manner is known (see Patent Documents 1 to 6). For example, the non-contact power transmission system described in Japanese Patent Application Laid-Open No. 2016-111903 (Patent Document 6) includes a power transmission coil, a power receiving coil, and a control means, as well as an inverter that converts DC power into AC power. It is further equipped with a filter that supplies power with a reduced high frequency of the output power of the inverter to the power transmission coil. The inverter includes a plurality of switching elements and a plurality of diodes, and is driven by PWM (Pulse Width Modulation) control. The filter includes a variable inductor. Then, the control means estimates the coupling coefficient between the power transmission coil and the power receiving coil (hereinafter, also simply referred to as “coupling coefficient”), and controls the variable inductor so that the inductance of the filter increases as the coupling coefficient increases.

Japanese Unexamined Patent Publication No. 2013-154815 Japanese Unexamined Patent Publication No. 2013-146154 Japanese Unexamined Patent Publication No. 2013-146148 Japanese Unexamined Patent Publication No. 2013-110822 Japanese Unexamined Patent Publication No. 2013-126327 Japanese Unexamined Patent Publication No. 2016-111903

When the phase of the output current of the inverter (hereinafter, also referred to as "current phase") is advanced with respect to the phase of the output voltage of the inverter (hereinafter, also referred to as "voltage phase"), the recovery characteristics of the diodes constituting the inverter are used. It is known that a recovery current (short circuit current) flows through a diode. The larger the recovery current, the larger the power loss (so-called switching loss). Therefore, in the non-contact power transmission system described in Patent Document 6, the current phase of the inverter is delayed by increasing the inductance of the filter to suppress the generation of the recovery current.

However, it is difficult to improve the output power factor of the inverter in a wide coupling coefficient range by the technique disclosed in Patent Document 6. For example, in the above control method, the larger the coupling coefficient, the larger the inductance of the filter. Therefore, when the coupling coefficient is large, it is considered that the difference between the voltage phase and the current phase of the inverter (hereinafter referred to as “output phase difference”) becomes large, and the output power factor of the inverter decreases. When the output power factor of the inverter decreases, the power transmission efficiency (ratio of the received power to the transmitted power) decreases.

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 capable of improving the output power factor of an inverter in a wide coupling coefficient range.

The non-contact power transmission device in the present disclosure is a non-contact power transmission device that non-contactly transmits power from a power transmission coil to a power reception coil of a power receiving device, and includes an inverter, an LC resonance unit, a capacitive reactance adjusting unit, and a control unit. Be prepared. The inverter is configured to convert the input power into AC power having a predetermined frequency and output the power. The LC resonance portion is provided on the output side of the inverter, and is configured by connecting a power transmission coil and a capacitor in series. The capacitive reactance adjusting unit is configured so that the capacitive reactance between the terminals of the LC resonance unit can be changed by an element connected in parallel to the LC resonance unit. The control unit is configured to control the capacitive reactance adjusting unit. The reactance between the inverter and the capacitive reactance adjusting unit is inductive reactance by an inductor connected in series with the LC resonance unit.

Then, in the control unit, the difference between the inductive reactance and the capacitive reactance at the predetermined frequency (that is, the frequency of the output power of the inverter) as the coupling coefficient between the transmission coil and the power receiving coil increases. It is configured to reduce (absolute value). Hereinafter, the frequency of the output power of the inverter may be simply referred to as "output frequency". Further, the capacitive reactance between the terminals of the LC resonance portion _{may be referred to as "reactance X C} " or simply "X _C ". Further, the inductive reactance between the inverter and the capacitive reactance adjuster, also referred to as a "reactance X _L", or simply "X _L". Further, the difference between _{X L} of _{X C} the output frequency of the output frequency (absolute value) "of the output frequency _| X L -X _C |" may be referred to as.

In the contactless power transmission apparatus, X _L and X _C of the output frequency when the coupling coefficient is small, for example, pre-set the output power factor of the inverter is high enough to match the predetermined criterion coupling coefficient (smaller coupling coefficient) can do. This makes it possible to secure a sufficient output power factor of the inverter when the coupling coefficient is small.

However, as the coupling coefficient increases, the coupling coefficient deviates from the above reference coupling coefficient. Therefore, when the coupling coefficient is large, maintaining the X _L and X _C of the output frequency to a value when the coupling coefficient is small, the output power factor of the inverter decreases.

Therefore, the control unit of the non-contact power transmitting device in the present disclosure, the coupling coefficient between the power transmission coil and the receiving coil is the output frequency in accordance with increases | reduce the _| X L _-X C. If the coupling coefficient is larger, the output frequency _| X L _-X C | even if is reduced, the output phase difference of the inverter (and therefore the output power factor of the inverter) is changed. However, since the direction of change is reversed in both the coupling coefficient of the output frequency in accordance with increases _| X L _-X C | By reducing the output power factor of the inverter caused by the coupling coefficient is increased Can be suppressed. Therefore, the output frequency as described above _| X L _-X C | By controlling, in the case the coupling coefficient not only the coupling coefficient is smaller is larger, to ensure the output power factor of sufficient inverter Will be possible. As described above, according to the non-contact power transmission device, it is possible to improve the output power factor of the inverter in a wide coupling coefficient range.

The control unit may detect the coupling coefficient between the power transmission coil and the power reception coil by using the output current of the inverter. With such a configuration, the coupling coefficient can be easily detected. In the non-contact power transmission device in the present disclosure, since the fluctuation of the output power factor of the inverter due to the fluctuation of the coupling coefficient becomes small, even if the coupling coefficient is simply detected, the output power factor of the inverter is sufficient in a wide coupling coefficient range. Easy to secure.

Non-contact power transmitting device of the above is capable of changing the reactance X _L by elements connected in series to the LC resonance part may further comprise an inductive reactance adjuster that is controlled by the control unit. The above-described control unit is configured to change the X _L and X _C of the output frequency according to the coupling coefficient between the transmitting coil and the receiving coil, the coupling coefficient of the output frequency in accordance with increases | X _L -X _C | May be reduced. Also reactance X _L in addition to the reactance X _C By enabling change reactance of the circuit (and hence impedance) increases the design flexibility, while suppressing a decrease in the output power factor of the inverter, power loss in the circuit It becomes easy to suppress the decrease.

Capacitive reactance adjuster, a plurality of reactance X _C which is set stepwise may be switchably configured. Further, the inductive reactance adjustment portion, a plurality of reactance X _L which is set stepwise may be switchably configured. Stepwise switching of each reactance can be easily realized using a switch. Further, by allowing change of each of the reactance X _L and X _C in a plurality of stages, the output frequency | X L _-X C _| is changeable in a wide range.

Switching the number of stages of reactance X _C of the capacitive reactance adjustment portion may be larger than the switching stages of the reactance X _L of the inductive reactance adjuster. It is easier to realize at low cost by increasing the number of switching stages of _{reactance X C} rather than increasing the number of switching stages of reactance X _L.

Switching capacitive reactance adjuster, a reactance _{X C,} the first _{X C,} and a second _{X C} is greater than the first _{X C,} and a third _{X C} is greater than the second _{X C} capable constructed, the inductive reactance adjusting unit, as the reactance X _L, a first X _L, and a second X _L may be switchably configured larger than the first X _L. Then, the above control unit determines whether the coupling coefficient is small, medium, or large, and if the coupling coefficient is small, the first X _C and the first _XL are adopted, and the coupling coefficient is medium. in some cases it adopted second X _C and the first X _L, when the coupling coefficient is large, may be employed third X _C and the second X _L.

The capacitive reactance adjusting unit includes a capacitor and a switching element (hereinafter, also referred to as “C switch”) connected in series with the capacitor as an element connected in parallel to the LC resonance unit, and is in the state of the C switch. (ON / OFF) by may be capable of changing the reactance _{X C.} Further, the capacitive reactance adjusting unit may include two or more sets of a capacitor connected in parallel to the LC resonance unit and a C switch (hereinafter, also referred to as “C variable unit”). _{According to such a capacitive reactance adjusting unit, the reactance X C} can be switched in multiple stages by changing the state (ON / OFF) of the C switch of each C variable unit.

The inductive reactance adjusting unit includes an inductor (for example, a coil) and a switching element (hereinafter, also referred to as “L switch”) connected in parallel to the inductor as elements connected in series to the LC resonance unit. it may be capable of changing the reactance _{X L} by the state of the L switch (ON / OFF).

The above-mentioned inverter may be configured so that the output frequency can be changed in a predetermined frequency range (hereinafter, also referred to as “output frequency range”). Moreover, reactance X _C and X _L is a certain frequency (hereinafter, referred to as "crossover frequency") in the output frequency range of the inverter may coincide with. According to such a configuration, the output power factor of the inverter can be set to 1 or substantially 1 by adjusting the output frequency of the inverter to the intersection frequency.

According to the present disclosure, it becomes possible to provide a non-contact power transmission device capable of improving the output power factor of an inverter in a wide coupling coefficient range.

It is an overall block diagram of the electric power transmission system to which the non-contact power transmission apparatus which concerns on embodiment of this disclosure is applied. It is a figure which shows the structure for performing non-contact electric power transmission between a charging facility and a vehicle. The non-contact power transmission control according to the embodiment of the present disclosure, is a diagram illustrating a reactance X _C and X _L when the coupling coefficient is small. It is a figure which shows the output phase difference of the inverter when the coupling coefficient is small in the non-contact power transmission apparatus which concerns on embodiment of this disclosure. It is a figure which shows the output power factor of the inverter when the coupling coefficient is small in the non-contact power transmission apparatus which concerns on embodiment of this disclosure. The non-contact power transmission control according to the embodiment of the present disclosure, is a diagram illustrating a reactance X _C and X _L when the coupling coefficient is medium. It is a figure which shows the output phase difference of the inverter when the coupling coefficient is medium in the non-contact power transmission apparatus which concerns on embodiment of this disclosure. It is a figure which shows the output power factor of the inverter when the coupling coefficient is medium in the non-contact power transmission apparatus which concerns on embodiment of this disclosure. The non-contact power transmission control according to the embodiment of the present disclosure, is a diagram illustrating a reactance X _C and X _L when the coupling coefficient is large. It is a figure which shows the output phase difference of the inverter when the coupling coefficient is large in the non-contact power transmission apparatus which concerns on embodiment of this disclosure. It is a figure which shows the output power factor of the inverter when the coupling coefficient is large in the non-contact power transmission apparatus which concerns on embodiment of this disclosure. In Comparative Example, a diagram illustrating a reactance X _C and X _L when the coupling coefficient is medium. In the comparative example, it is a figure which shows the output phase difference of the inverter when the coupling coefficient is medium. In the comparative example, it is a figure which shows the output power factor of the inverter when the coupling coefficient is medium. It is a flowchart which shows the processing procedure of the power transmission start control executed by the non-contact power transmission apparatus which concerns on embodiment of this disclosure. It is a flowchart which shows the processing procedure of the power transmission control executed by the non-contact power transmission apparatus which concerns on embodiment of this disclosure. The non-contact power transmission control according to the embodiment of the present disclosure, X _L of the output frequency _is a diagram showing the relationship between X _C and the coupling coefficient. It is a figure which shows the transmission efficiency of electric power in the non-contact transmission control which concerns on embodiment of this disclosure in comparison with the transmission efficiency of electric power in the non-contact transmission control which concerns on a comparative example. It is a figure which shows the charge power in the non-contact power transmission control which concerns on embodiment of this disclosure in comparison with the charge power in the non-contact power transmission control which concerns on a comparative example. It is a flowchart which shows the processing procedure of the power transmission control in the modification which starts the power transmission under the condition C. It is a flowchart which shows the processing procedure of the power transmission control executed by the non-contact power transmission apparatus in the modification of the method of detecting a coupling coefficient. It is a figure which shows the 1st modification example of a capacitive reactance adjustment part and an inductive reactance adjustment part. It is a figure which shows the 2nd modification of the capacitive reactance adjustment part and the inductive reactance adjustment part. It is a figure which shows the 3rd modification example of a capacitive reactance adjustment part and an inductive reactance adjustment part. Is a diagram showing a modified example of the reactance X _L to a fixed.

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

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

FIG. 1 is an overall configuration diagram of a power transmission system to which the non-contact power transmission device according to the embodiment of the present disclosure is applied. The power transmission system 10 includes a charging facility 1 and a vehicle 2.

The charging equipment 1 includes a power transmission device 100 and an AC power source 700 that supplies electric power to the power transmission device 100. The power transmission device 100 is installed on the ground F10 (for example, the floor surface of a parking lot). Examples of the AC power supply 700 include a household power supply (for example, an AC power supply having a voltage of 200 V and a frequency of 50 Hz). The power transmission device 100 according to this embodiment corresponds to an example of the "contactless power transmission device" according to the present disclosure.

The vehicle 2 includes a power receiving device 200, a power storage device 300 charged by the power received by the power receiving device 200, and a vehicle ECU 500 that controls the power received by the power receiving device 200. The power receiving device 200 is provided on the lower surface (road surface side) of the power storage device 300 installed on the bottom surface F20 of the vehicle 2. The vehicle 2 may be an electric vehicle that can travel using only the electric power stored in the power storage device 300, or uses both the power stored in the power storage device 300 and the output of the engine (not shown). It may be a hybrid vehicle that can run on the vehicle.

The power transmission device 100 is configured to transmit power to the power receiving device 200 in a non-contact manner through a magnetic field in a state where the vehicle 2 is aligned so that the power receiving device 200 of the vehicle 2 faces the power transmitting device 100. The power receiving device 200 receives the electric power from the power transmitting device 100 in a non-contact manner.

Hereinafter, the height from the wheel installation surface of the vehicle 2 (that is, the ground F10) to the power receiving coil of the power receiving device 200 is referred to as “power receiving coil height ΔH”. In this embodiment, the power receiving coil height ΔH of the vehicle 2 coincides with the minimum ground clearance of the vehicle 2. The distance between the power transmitting coil provided on the surface of the power transmitting device 100 and the power receiving coil provided on the surface of the power receiving device 200 (hereinafter referred to as “coil-to-coil distance ΔG”) varies depending on the height of the power receiving coil ΔH. As the height of the power receiving coil ΔH increases, the distance between the coils ΔG also increases. Further, as the distance between the coils ΔG increases, the coupling coefficient between the power transmission coil and the power reception coil tends to decrease. The height of the power receiving coil ΔH differs depending on the vehicle.

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

With reference to FIG. 2, the power transmission device 100 obtains power for transmission by performing a predetermined power conversion process on the power received from the AC power source 700, and transmits the power for power transmission to the power reception device 200 in a non-contact manner. It is composed of. Then, the power storage device 300 (vehicle-mounted battery) is charged by the electric power received from the power transmission device 100 by the power receiving device 200.

The power transmission device 100 includes a power conversion unit that performs the power conversion process, and a power transmission ECU 150 that controls the power conversion unit. The power conversion unit includes a filter circuit 110, an inverter 120, and an AC / DC converter 130. Further, a power monitoring unit 140 is provided between the filter circuit 110 and the inverter 120. The power monitoring unit 140 includes a current sensor that detects the output current of the inverter 120 (for example, the current flowing through the power line PL1 shown below) and a voltage sensor that detects the output voltage of the inverter 120.

The power transmission device 100 further includes an LC resonance unit R1 that performs non-contact power transmission to the power reception device 200, and a communication unit 160 that performs wireless communication with the power reception device 200. The LC resonance unit R1 is provided on the output side of the inverter 120, and is configured by connecting the power transmission coil 101 and the capacitor 102 in series. Hereinafter, the terminal on the power transmission coil 101 side of the LC resonance unit R1 will be referred to as an “L terminal”, and the terminal on the capacitor 102 side of the LC resonance unit R1 will be referred to as a “C terminal”. Further, the electric wire connecting the L terminal of the LC resonance portion R1 and the terminal T1 of the inverter 120 is referred to as "power line PL1", and the electric wire connecting the C terminal of the LC resonance portion R1 and the terminal T2 of the inverter 120 is referred to as "power line PL2".

The AC / DC converter 130 rectifies and transforms the electric power received from the AC power supply 700 and outputs it to the inverter 120. The AC / DC converter 130 boosts the power received from, for example, the AC power supply 700 to 400V, and outputs DC power having a voltage of 400V to the inverter 120.

The inverter 120 is configured to convert the input power (more specifically, DC power) from the AC / DC converter 130 into AC power having a predetermined frequency and output it to the LC resonance unit R1. The inverter 120 is composed of, for example, a single-phase full bridge circuit including a plurality of switching elements (for example, a power semiconductor switching element) and a plurality of diodes. Each switching element constituting the inverter 120 is PWM controlled by the power transmission ECU 150. The inverter 120 is driven by a PWM-controlled switching frequency (drive frequency). The drive frequency of the inverter 120 coincides with the output frequency of the inverter 120, and thus the transmission frequency (frequency of transmission power). Hereinafter, the output angular frequency of the inverter 120 may be referred to as “ω”. For example, "ω" in each equation described later represents the output angular frequency of the inverter 120.

The inverter 120 is configured so that the output frequency can be changed in a predetermined output frequency range. In this embodiment, the output frequency range of the inverter 120 is set to 80 kHz or more and 90 kHz or less. The output frequency of the inverter 120 is controlled as follows, for example.

The LC resonance section R1 and the LC resonance section R2, which will be described later, are both designed to resonate at the same frequency (hereinafter, also referred to as “design resonance frequency”), but component variation (difference in performance among components). ) And the like, the resonance frequency of each LC resonance portion may deviate from the design resonance frequency, and the resonance frequency of the LC resonance portion R1 and the resonance frequency of the LC resonance portion R2 may not match. In such a case, the power transmission ECU 150 controls to match the output frequency of the inverter 120 with the resonance frequency of the LC resonance unit R2. By such control, the transmission efficiency of electric power from the LC resonance unit R1 to the LC resonance unit R2 becomes high. Hereinafter, as an example, a case where the resonance frequency of the LC resonance unit R2 is 88 kHz and the output frequency of the inverter 120 is controlled to 88 kHz will be described.

The filter circuit 110 includes a capacitive reactance adjusting unit 110C and an inductive reactance adjusting unit 110L. The capacitive reactance adjusting unit 110C includes elements (capacitors C11a, C11b, C11c and switches 113b, 113c) connected in parallel to the LC resonance unit R1, and the capacitive reactance (capacitive reactance between the terminals of the LC resonance unit R1) is provided by such elements. Resonance X _C ) can be changed. Further, the inductive reactance adjusting unit 110L includes an element (coils L11a, L11b and a switch 114) connected in series with the LC resonance unit R1, and the induction between the inverter 120 and the capacitive reactance adjusting unit 110C by such an element. changeable configured sex reactance (reactance _{X L).} The reactance between the inverter 120 and the capacitive reactance adjusting unit 110C is an inductive reactance due to an inductor (coil L11a or the like) connected in series with the LC resonance unit R1.

The capacitor C11a is connected in parallel to the LC resonance portion 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 113b are connected in parallel to the LC resonance portion R1 on the LC resonance portion R1 side of the capacitor C11a. Further, the capacitor C11b and the switch 113b are connected in series with each other. One end of the capacitor C11b is connected to the power line PL2 via the switch 113b, and the other end of the capacitor C11b is connected to the power line PL1. The switch 113b connected in series with the capacitor C11b corresponds to a C switch. Hereinafter, the switch 113b is also referred to as a “C1 switch”.

The capacitor C11c and the switch 113c are connected in parallel to the LC resonance portion R1 on the LC resonance portion R1 side of the capacitor C11b. Further, the capacitor C11c and the switch 113c are connected in series with each other. One end of the capacitor C11c is connected to the power line PL2 via the switch 113c, and the other end of the capacitor C11c is connected to the power line PL1. The switch 113c connected in series with the capacitor C11c corresponds to a C switch. Hereinafter, the switch 113c is also referred to as a “C2 switch”.

Reactance _{X C} is changed by the state of C switches constituting the capacitive reactance adjuster 110C (ON / OFF). More specifically, when the capacitances of the capacitors C11a, C11b, and C11c are expressed as C _11a , C _11b , and C _{11c , respectively, the reactance X C} when both the C1 switch and the C2 switch are OFF (hereinafter, "X _{C1"). The reactance X C} (hereinafter _{referred to as “X C2} ”) when the C1 switch is ON and the C2 switch is OFF is the equation (1), and the C1 switch and the C2 are expressed in the equation (2). _{The reactance X C} (hereinafter _{referred to as “X C3} ”) when both switches are ON can be expressed by the equation (3).

The coils L11a and L11b are provided on the power line PL2 (more specifically, on the inverter 120 side of the node to which the capacitor C11a and the power line PL2 are connected). The coil L11a and the coil L11b are connected in series with each other. Further, the switch 114 is connected in parallel with the coil L11b. When the switch 114 is turned on (closed), the terminals of the coil L11b are short-circuited. The switch 114 connected in parallel to the coil L11b corresponds to an L switch.

The state of the L switches constituting the inductive reactance adjuster 110L (ON / OFF) changes the reactance _{X L.} More specifically, the coil L11a, respectively _L 11a inductance _L11b, expressed as _{L 11b,} the reactance _{X L} (hereinafter, referred to as _{"X L1")} when L switch is OFF by the formula (4) , reactance _{X L} (hereinafter, referred to as _{"X L2")} when L switch is ON can be expressed by equation (5).

As shown in equation _{(1) ~ (3),} X C1 becomes smaller towards the _{X C2} than _{(X C1>} X _C2), towards the _{X C3} is smaller than the _{X C2 (X C2> X C3} ). Further, as shown in equation (4) and _(5), towards the _{X L2} is greater than _{X L1 (X L1 <X L2} ). In this embodiment, for example, an electromagnetic mechanical relay is adopted as each of the switches 113b, 113c and 114. Mechanical relays are cheaper and easier to obtain than semiconductor relays (transistors, etc.).

In the filter circuit 110, the LC filter is formed by the above-mentioned capacitors C11a, C11b, C11c and the coils L11a, L11b. This LC filter functions as a low-pass filter. Then, the harmonics included in the output current of the inverter 120 are reduced by this LC filter.

The LC resonance unit R1 transmits power to the LC resonance unit R2 of the power receiving device 200 in a non-contact manner through a magnetic field generated around the power transmission coil 101. Electric power is transmitted from the power transmission coil 101 to the power reception coil 201 by magnetic resonance. The LC resonant portion R1 is a series resonant circuit. The Q value of the LC resonance portion R1 is preferably 100 or more. In addition, in order to control the transmitted power with high accuracy, a current sensor (not shown) for detecting the current flowing through the LC resonance unit R1 may be provided.

The power transmission ECU 150 includes an arithmetic unit, a storage device, an input / output port, a communication port (none of which is shown), and the like. The arithmetic unit is composed of a microprocessor including a CPU (Central Processing Unit). The storage device includes a RAM (Random Access Memory) for temporarily storing data and a storage (ROM (Read Only Memory), a rewritable non-volatile memory, etc.) for storing programs and the like. The power transmission ECU 150 controls various devices in the power transmission device 100. Various controls are not limited to software processing, but can also be processed by dedicated hardware (electronic circuits). The power transmission ECU 150 according to this embodiment corresponds to an example of the "control unit" according to the present disclosure.

The communication unit 160 is a communication interface for performing wireless communication with the power receiving device 200. The communication unit 160 sends information to the power receiving device 200 and receives information from the power receiving device 200.

The power receiving device 200 includes an LC resonance unit R2, a capacitor 203, an inductor 204, a rectifier circuit 205, capacitors 206a and 206b for adjusting the load impedance, and a capacitor 207 for smoothing.

The LC resonance portion R2 is configured by connecting the power receiving coil 201 and the capacitor 202 in series. The power receiving coil 201 receives power from the power transmission coil 101 of the power transmission device 100 in a non-contact manner through a magnetic field. The LC resonant portion R2 is a series resonant circuit. The Q value of the LC resonance portion R2 is preferably 100 or more.

The LC filter is formed by the capacitor 203 and the inductor 204. This LC filter suppresses the harmonic noise generated when the power is received. The rectifier circuit 205 rectifies the AC power received by the power receiving coil 201 and outputs it to the power storage device 300 side. The rectifier circuit 205 is composed of, for example, a diode bridge circuit composed of four diodes. Capacitors 206a and 206b for adjusting the load impedance and capacitors 207 for smoothing are provided on the output side of the rectifier circuit 205. The capacitor 207 smoothes the DC power rectified by the rectifier circuit 205.

The DC power smoothed by the capacitor 207 is output from the power receiving device 200 and supplied to the power storage device 300 via the charging relay 400. The charging relay 400 is ON / OFF controlled by the vehicle ECU 500, and is turned ON (conducting state) when the power storage device 300 is charged by the power receiving device 200.

The power storage device 300 is a rechargeable DC power source. The power storage device 300 includes, for example, a secondary battery (a lithium ion battery, a nickel hydrogen battery, or the like). The power storage device 300 stores the electric power supplied from the power receiving device 200 and supplies the electric power to a vehicle driving device (inverter, drive motor, etc.) (not shown).

The power storage device 300 is provided with a battery monitoring unit 310 for monitoring the state of the power storage device 300. The battery monitoring unit 310 includes various sensors for detecting the state (temperature, current, voltage, etc.) of the power storage device 300, and outputs the detection result to the vehicle ECU 500. The vehicle ECU 500 is configured to detect a state (SOC (State Of Charge) or the like) of the power storage device 300 based on the output of the battery monitoring unit 310. The SOC indicates the remaining amount of electricity stored, and for example, the ratio of the current amount of electricity stored to the amount of electricity stored in the fully charged state is expressed by 0 to 100%.

The vehicle ECU 500 includes an arithmetic unit, a storage device, an input / output port, a communication port (none of which is shown), and the like, and controls various devices in the vehicle 2. The arithmetic unit is composed of a microprocessor including a CPU. The storage device includes RAM and ROM. The ROM stores programs and the like. ON / OFF signals and the like from the vehicle ECU 500 to the charging relay 400 are output from the output port. The vehicle ECU 500 executes, for example, travel control of the vehicle 2 and charge control of the power storage device 300. Various controls are not limited to software processing, but can also be processed by dedicated hardware (electronic circuits).

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 device 100. By performing wireless communication between the communication unit 160 of the power transmission device 100 and the communication unit 600 of the vehicle 2, information can be exchanged between the power transmission ECU 150 and the vehicle ECU 500.

Hereinafter, the output power factor of the inverter 120 in the power transmission device 100 will be described.
When the output power factor of the inverter 120 is represented by "λ" and the output phase difference of the inverter 120 is represented by "φ", λ and φ satisfy a relational expression such as “λ = | cosφ |”. The output phase difference φ is expressed with reference to the voltage phase. That is, when the current phase is shifted to the retard side with respect to the voltage phase, the output phase difference becomes a positive value, and when the current phase is shifted to the advance angle side with respect to the voltage phase, the output position is reached. The phase difference becomes a negative value. 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), and if the output phase difference is 90 ° or −90 °, the output power factor of the inverter 120 is 1. The power factor is 0 (only reactive power).

The output phase difference φ of the inverter 120 can be expressed by the following equation (6).

In the formula (6), _{p e} is the output power of the power receiving device 200. [Delta] X _LC is a value obtained by subtracting the _{X C} from _{X L (= X L -X C} ). V ₂ is the input voltage of the rectifier circuit 205.

In equation (6), x _a , x _b , and x _m are represented by equations (7-1), (7-2), (8), and (9), respectively, as shown below. Will be done. _{“Ω 1} ” represented by the equation (7-2) corresponds to the resonance angular frequency of the LC resonance portion R1.

In equations (7-1), (7-2), (8), and (9), L ₁ is the inductance of the power transmission coil 101, C ₁ is the capacitance of the capacitor 102, and L ₂ is. It is the inductance of the power receiving coil 201, and C ₂ is the capacitance of the capacitor 203. C ₁₁ is the capacitance of the capacitive reactance adjusting unit 110C, for example, "C _{11a " when both the C1 switch and the C2 switch are OFF, and "C 11a} + C" when both the C1 switch and the C2 switch are ON. _11b + C _11c ". k is a coupling coefficient between the power transmission coil 101 and the power reception coil 201.

Next, the power loss in the power transmission device 100 will be described.
The main power losses in the power transmission device 100 are coil loss and switching loss. Switching loss is a power loss that occurs during a switching operation (turn-on or turn-off). In the power transmission device 100, the power loss due to the recovery current generated at the turn-on of the switching element constituting the inverter 120 is the dominant switching loss. The coil loss is a conduction loss (loss due to heat generation or the like) in a coil (transmission coil 101 or the like).

The power loss (coil loss) in the power transmission coil 101 tends to decrease as the coupling coefficient increases. Further, when the output phase difference of the inverter 120 becomes large on the advance angle side, the switching operation of the inverter 120 becomes so-called hard switching, and the power loss due to the recovery current tends to increase.

By the way, it is possible to delay the current phase of the inverter 120 by increasing the inductance of the LC filter provided on the output side of the inverter 120, and suppress the power loss due to the recovery current. However, when the output phase difference of the inverter 120 becomes large, the output power factor of the inverter 120 decreases. When the output power factor of the inverter 120 decreases, the power transmission efficiency decreases.

Therefore, power transmission ECU150 of the power transmission apparatus 100 according to this embodiment, in accordance with the coupling coefficient between the transmitting coil 101 and the receiving coil 201 is increased, the difference between the _{X C} of _{X L} and the output frequency of the output frequency (output frequency | X _L- X _C |) is configured to be small.

As it can be understood from formula (6), when the coupling coefficient ( "k" in the equation (9)) is larger, the output frequency _| X L _-X C _| (in the formula (6) " Even when _{the absolute value of “ΔX LC} ” becomes smaller, the output phase difference of the inverter 120 (and thus the output power factor of the inverter 120) changes. However, since the direction of change is reversed at both the output frequency in accordance with the coupling coefficient is increased _| X L _-X C | By the smaller, the output power of the inverter 120 due to the coupling coefficient is increased The decrease in the rate can be suppressed.

Hereinafter, with reference to FIGS. 3 to 11, in the power transmitting apparatus 100 according to this embodiment, in accordance with the coupling coefficient increases, the reactance X _C and X _L, and the output phase difference and the output power factor of the inverter 120 is what Explain how it changes. The range of the power transmission frequency (80 kHz to 90 kHz) shown on the horizontal axis of each of FIGS. 3 to 11 corresponds to the output frequency range of the inverter 120.

3, in the contactless power transmission control according to this embodiment, a diagram illustrating a reactance X _C and X _L when the coupling coefficient is small.

When the coupling coefficient is small (for example, when the coupling coefficient is about 0.1), the power transmission ECU 150 sets the states of the L switch, the C1 switch, and the C2 switch to OFF, ON, and ON (first state), respectively. .. As a result, the reactance X _C becomes X _C3 (see equation (3)), and the reactance X _{L becomes XL 1} (see equation (4)). Hereinafter, the condition in which the L switch is OFF and both the C1 switch and the C2 switch are ON may be referred to as "condition A". In this embodiment, the reactance X _L of the condition A at the output frequency range of the inverter 120 becomes a value as indicated by line A1 in FIG. 3, the reactance X _C Figure conditions A at the output frequency range of the inverter 120 3 The value is as shown by the line B1 in the middle.

Referring to FIG. 3, in this embodiment, the reactance X _C and X _L in condition A so that the output power factor of the inverter 120 is sufficiently high when the coupling coefficient is 0.1 (the reference coupling coefficient) It is set in advance. More specifically, in the selection of the components (coils, capacitors, etc.) constituting the circuit shown in FIG. 2, at least at the output frequency (preferably over the entire output frequency range) based on the above equation (6). The parts are selected so that the output power factor of the inverter 120 is sufficiently high. Incidentally, the selection of components, described later condition B, reactance X _C and X _L of C is also performed in consideration.

Further, in this embodiment, across the output frequency range of the inverter 120, so that the reactance _{X L} (line A1) is larger than the reactance _{X C} (line B1), a reactance _{X C} and _{X L} in condition A It is set. That is, even if the output frequency of the inverter 120 is controlled to any frequency within the output frequency range of the inverter 120, X _L of the output frequency is greater than X _C of the output frequency.

(In this embodiment, 88 kHz) the output frequency under the condition A of _| X L -X _{C | ΔX1} showing a is, for example 10Ω or more.

4, in the power transmitting apparatus 100, reactance _{X C} and _{X L} is the reactance (reactance _{X C} and _{X L} condition A) as shown in FIG. 3, and, when the coupling coefficient is about 0.1 It is a figure which shows the output phase difference of an inverter 120.

Referring to FIG. 4, the reactance X _C and X _L, as shown in FIG. 3, over the entire output frequency range of the inverter 120, the output phase of the inverter 120 becomes a positive value (the retard side).

5, in the power transmitting apparatus 100, reactance _{X C} and _{X L} is the reactance (reactance _{X C} and _{X L} condition A) as shown in FIG. 3, and, when the coupling coefficient is about 0.1 It is a figure which shows the output power factor of an inverter 120.

Referring to FIG. 5, the reactance X _C and X _L shown in FIG. 3, the coupling coefficient is set in accordance with when it is 0.1. Although not fully as designed by parts and variation, the set reactance X _C and X _L as described above, the output power factor of the inverter 120 when the coupling coefficient of about 0.1 is high. Further, in the filter circuit 110 under the condition A, stable power transmission can be performed when the coupling coefficient is about 0.1 (that is, no overcurrent occurs).

6, in the contactless power transmission control according to this embodiment, a diagram illustrating a reactance X _C and X _L when the coupling coefficient is medium.

When the coupling coefficient is medium (for example, about 0.3), the power transmission ECU 150 sets the states of the L switch, the C1 switch, and the C2 switch to OFF, ON, and OFF (second state), respectively. As a result, the reactance X _C becomes X _C2 (see equation (2)), and the reactance X _L becomes _XL1 (see equation (4)). Hereinafter, the condition that the L switch is OFF, the C1 switch is ON, and the C2 switch is OFF may be referred to as "condition B". In this embodiment, the reactance X _L of the condition B in the output frequency range of the inverter 120 becomes a value shown by a line in FIG. 6 A1 (same as the line A1 in FIG. 3), the output frequency range of the inverter 120 reactance X _C condition B becomes a value shown by the line B2 in FIG. 6 in.

Referring to FIG. 6, in this embodiment, and greater than X _C of X _{C (line} B2) condition A condition B across the output frequency range of the inverter 120 _(see line B1 in FIG. 3) and while being, _{X L} (line A1) of the condition B is the same as _{X L} condition a (see the line A1 in FIG. 3). That is, the difference between X _L and X _C under the condition B (absolute value) is smaller than when the condition A across the output frequency range of the inverter 120.

6, (in this embodiment, 88 kHz) the output frequency under the condition B of _| X L -X _{C | ΔX2} showing a is smaller than ΔX1 conditions A (see FIG. 3). ΔX2 is, for example, 5Ω or more and less than 10Ω.

7, the power transmission device 100, the reactance _{X C} and _{X L} is the reactance (reactance _{X C} and _{X L} condition B), as shown in FIG. 6, and, when the coupling coefficient is about 0.3 It is a figure which shows the output phase difference of an inverter 120.

Referring to FIG. 7, the reactance X _C and X _L, as shown in FIG. 6, over the entire output frequency range of the inverter 120, the output phase of the inverter 120 becomes a positive value (the retard side).

8, in the power transmission device 100, the reactance _{X C} and _{X L} is the reactance (reactance _{X C} and _{X L} condition B), as shown in FIG. 6, and, when the coupling coefficient is about 0.3 It is a figure which shows the output power factor of an inverter 120.

Referring to FIG. 8, the reactance _{X C} and _{X L} shown in FIG. 6, the output frequency _| X L -X _C | is smaller than when the condition A (i.e., if the coupling coefficient is small) .. As a result, the decrease in the output power factor of the inverter 120 due to the increase in the coupling coefficient is suppressed. In the example of FIG. 8, the output power factor of the inverter 120 at the output frequency (88 kHz in this embodiment) is about 0.4. In the filter circuit 110 of the condition B, stable power transmission can be performed when the coupling coefficient is about 0.3 (that is, no overcurrent occurs).

9, in the contactless power transmission control according to this embodiment, a diagram illustrating a reactance X _C and X _L when the coupling coefficient is large.

When the coupling coefficient is large (for example, when the coupling coefficient is about 0.6), the power transmission ECU 150 sets the states of the L switch, the C1 switch, and the C2 switch to ON, OFF, and OFF (third state), respectively. .. As a result, the reactance X _C becomes X _C1 (see equation (1)), and the reactance X _L becomes _XL2 (see equation (5)). Hereinafter, the condition in which the L switch is ON and both the C1 switch and the C2 switch are OFF may be referred to as "condition C". In this embodiment, the reactance X _L of the condition C in the output frequency range of the inverter 120 becomes a value as indicated by the line A2 in FIG. 9, the reactance X _C of condition C in the output frequency range of the inverter 120 in FIG. 9 The value is as shown by the line B3 in the middle.

Referring to FIG. 9, in this embodiment, across the output frequency range of the inverter 120, greater than X _C of X _{C (line} B3) condition B condition C _(see the line B2 in FIG. 6) and, and, and larger than the condition C of the _{X L} of the (line A2) condition B _{X L} (see line A1 in FIG. 6). That is, even if the output frequency of the inverter 120 is controlled to any frequency within the output frequency range of the inverter 120, each of X _L and X _C of the output frequency in the condition C is larger than the value when the condition B.

Further, in FIG. 9, (in this embodiment, 88 kHz) the output frequency under the condition C of _| X L -X _{C | ΔX3} showing a is smaller than the condition B .DELTA.X2 (see FIG. 6). ΔX3 is, for example, less than 5Ω.

Reactance _{X C} and _{X L} condition C has an intersection point P in the output frequency range. That is, the reactance of the condition C _{X L} (line A2) and reactance _{X C} (line B3), coincides with the frequency of the intersection point P (crossover frequency). In the example of FIG. 9, the intersection frequency is about 86 kHz. Further, in the example of FIG. 9, the area than the intersection point P low frequency side is larger is X _C than (hereinafter, also referred to as "intersection low frequency side region of the P"), the X _L, higher than the intersection point P In the frequency side region (hereinafter, also referred to as “high frequency side region of intersection P”), _XL is larger than _{X C.} (In this embodiment, 88kH) the output frequency of the inverter 120 in, _{X L} is larger than _{X C.}

10, in the power transmission device 100, the reactance _{X C} and _{X L} is the reactance (reactance condition C _{X C} and _{X L)} as shown in FIG. 9, and, when the coupling coefficient is about 0.6 It is a figure which shows the output phase difference of an inverter 120.

Referring to FIG. 10, the reactance X _C and X _L, as shown in FIG. 9, is an output phase difference is a negative value of the inverter 120 (advance side) in the low-frequency side region of the intersection point P, the intersection P In the high frequency side region, the output phase difference of the inverter 120 becomes a positive value (retarded angle side).

11, the power transmission device 100, the reactance _{X C} and _{X L} is the reactance (reactance condition C _{X C} and _{X L)} as shown in FIG. 9, and, when the coupling coefficient is about 0.6 It is a figure which shows the output power factor of an inverter 120.

Referring to FIG. 11, the reactance _{X C} and _{X L} shown in FIG. 9, the output frequency _| X L -X _C | is, when the condition B (i.e., if the coupling coefficient is medium) less than It has become. As a result, the decrease in the output power factor of the inverter 120 due to the increase in the coupling coefficient is suppressed. In the example of FIG. 11, the output power factor of the inverter 120 at the output frequency (88 kHz in this embodiment) is about 0.9. In the filter circuit 110 of the condition C, stable power transmission can be performed when the coupling coefficient is about 0.6 (that is, no overcurrent occurs).

As shown in FIG. 11, the output power factor of the inverter 120 at the intersection frequency (about 86 kHz) is 1 or substantially 1. In this embodiment, the output frequency of the inverter 120 is controlled so as to match the resonance frequency of the LC resonance unit R2 (for example, 88 kHz), but the control method of the output frequency of the inverter 120 can be arbitrarily changed. For example, the output frequency of the inverter 120 may be controlled to match the intersection frequency to improve the output power factor of the inverter 120. Further, when the resonance frequency of the LC resonance portion R2 is lower than the intersection frequency (frequency of the intersection P in FIG. 9), the output frequency of the inverter 120 is set higher than the intersection frequency in order to suppress power loss due to the recovery current. You may. When the coupling coefficient is large, the power transmission efficiency does not significantly decrease even if the output frequency of the inverter 120 and the resonance frequency of the LC resonance portion R2 deviate slightly.

Next, a comparative example will be described with reference to FIGS. 12 to 14, and the non-contact power transmission control according to the comparative example will be compared with the non-contact power transmission control according to the above embodiment. The comparative example will mainly explain the differences from the above-described embodiment.

12, in the contactless power transmission control according to the comparative example, it illustrates a reactance X _C and X _L when the coupling coefficient is medium. Referring to FIG. 12, in this comparative example, the order of the coupling coefficient is medium (e.g., about 0.3) the reactance _{X C} and _{X L} when it is, reactance _{X C} and _X L when the coupling coefficient is small ( It is the same as (see Fig. 3).

13, the power transmission device according to FIG. 14, respectively, the comparative example, a reactance as the reactance X _C and X _L is shown in FIG. 12, and the output of the inverter when the coupling coefficient is about 0.3 It is a figure which shows the phase difference and the output power factor.

With reference to FIG. 13, the output phase difference of the inverter becomes about 90 ° due to the increase in the coupling coefficient and the increase in the mutual reactance (x _{m in the equation (6)).} As a result, as shown in FIG. 14, the output power factor of the inverter is lower than that in the graph (embodiment) of FIG.

As described above, in the non-contact power transmission control according to the comparative example, the output power factor of the inverter is worse than that in the non-contact power transmission control according to the above embodiment.

As described above, according to the power transmission device 100 according to this embodiment, it is possible to improve the output power factor of the inverter 120 in a wide coupling coefficient range.

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

First, the driver stops the vehicle 2 in the charging space of the charging equipment 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, 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 the instruction of the driver, or may be automatically transmitted when a predetermined condition is satisfied. When the power transmission ECU 150 receives the power transmission request, the power transmission ECU 150 starts the power transmission preparation.

The power transmission preparation is a process for making the power transmission system 10 ready for power transmission. For example, the power transmission device 100 and the power reception device 200 are aligned while the power transmission ECU 150 and the vehicle ECU 500 exchange information with each other. Further, when the charging equipment 1 includes a plurality of power transmission devices, a process (so-called pairing) for specifying which power transmission device the alignment is performed with may be performed as the power transmission preparation. .. Various methods are known as methods for alignment and pairing, and any method can be adopted.

When the above-mentioned power transmission preparation is completed, the power transmission ECU 150 starts power transmission for charging the power storage device 300 of the vehicle 2.

FIG. 15 is a flowchart showing a processing procedure of power transmission start control executed by the power transmission ECU 150. The process shown in this flowchart includes steps S11 to S13 (hereinafter, simply referred to as "S11" to "S13"), is called from the main routine, and is repeatedly executed. The process of FIG. 15 is repeatedly executed at predetermined time intervals, for example, in a situation where power transmission is not performed by the power transmission device 100 (that is, when power transmission is not performed), and ends when power transmission is started in S13.

With reference to FIG. 15, it is determined whether or not the power transmission ECU 150 has received the above-mentioned power transmission request from the vehicle ECU 500 (S11). Then, when it is determined that the power transmission ECU 150 has not received the power transmission request (NO in S11), the process is returned to the main routine.

On the other hand, when it is determined that the power transmission request has been received in S11 (YES in S11), the power transmission ECU 150 performs power transmission preparation (alignment, pairing, etc.) while performing wireless communication with the vehicle ECU 500 (S12). .. Then, when the power transmission preparation is completed, the power transmission ECU 150 starts power transmission under the condition A in which the switch 113b (C1 switch) is ON, the switch 113c (C2 switch) is ON, and the switch 114 (L switch) is OFF (S13). .. More specifically, the power transmission ECU 150 controls the inverter 120, the AC / DC converter 130, and the like after turning the switches 113b, 113c, and 114 on, ON, and OFF, respectively, from the power transmission coil 101 to the power reception coil 201. Send electricity. Further, the charging relay 400 is turned on by the vehicle ECU 500. Then, the power storage device 300 is charged by the electric power received by the power receiving coil 201. During charging of the power storage device 300 (that is, during power transmission by the power transmission device 100), control for increasing the power transmission power to a desired size is performed in addition to the control of FIG. 16 described below. While the power transmission ECU 150 and the vehicle ECU 500 exchange information with each other, the power transmission from the power transmission coil 101 to the power reception coil 201 is feedback-controlled.

FIG. 16 is a flowchart showing a processing procedure of power transmission control executed by the power transmission ECU 150. The process shown in this flowchart includes steps S21 to S27 (hereinafter, simply referred to as "S21" to "S27") and steps S31 to S34 (hereinafter, simply referred to as "S31" to "S34"), and is a main routine. Called from and executed repeatedly. The process of FIG. 16 is repeatedly executed at predetermined time intervals, for example, in a situation where power transmission is being performed by the power transmission device 100 (that is, during power transmission), and the process of FIG. 16 is also executed when the power transmission being executed in S26 is completed. finish.

With reference to FIG. 16, the power transmission ECU 150 determines whether or not power transmission is performed under the condition A (S21). For example, the power transmission ECU 150 confirms the state of each switch, and if the switches 113b, 113c, and 114 are ON, ON, and OFF, respectively, it is determined that power transmission is being performed under the condition A. On the other hand, if the states of the switches 113b, 113c, 114 are other than the above, it means that the power transmission is not performed under the condition A. In this embodiment, power transmission is started under condition A (see S13 in FIG. 15). Therefore, immediately after the start of power transmission, it is determined that power transmission is being performed under condition A (YES in S21), and the process proceeds to S22.

In S22, whether or not the output current of the inverter 120 detected by the power monitoring unit 140 (more specifically, the current sensor) is equal to or higher than a predetermined threshold value Th1 (hereinafter, also simply referred to as “Th1”). , The power transmission ECU 150 determines. Th1 is a threshold value for detecting an overcurrent. Th1 is, for example, an upper limit value of the output current of the inverter 120 obtained in consideration of the decrease in the output power factor of the inverter 120 which may occur due to the fluctuation of the resonance frequency and the coupling coefficient. Variations in resonance frequency can occur, for example, due to component variations. Fluctuations in the coupling coefficient may occur due to misalignment of the power transmitting / receiving coil and fluctuations in the height ΔH of the power receiving coil. Th1 may be a fixed value or may be variable depending on the situation of the vehicle 2 and the like.

When the output current of the inverter 120 is smaller than Th1 (NO in S22), it is determined that no overcurrent has occurred, and the process proceeds to S25. In S25, the power transmission ECU 150 determines whether or not the charging of the power storage device 300 is completed. The power transmission ECU 150 determines that charging is completed, for example, when a predetermined completion condition is satisfied. The completion condition is satisfied, for example, when the SOC of the power storage device 300 becomes larger than a predetermined SOC value during charging. During charging, the vehicle ECU 500 monitors the SOC of the power storage device 300, and when the above completion condition is satisfied, a signal indicating that the completion condition is satisfied is transmitted from the vehicle ECU 500 to the power transmission ECU 150. The predetermined SOC value may be automatically set by the vehicle ECU 500 or the like, or may be set by the user.

The above completion conditions can be changed arbitrarily. For example, the completion condition may be satisfied when the charging time (elapsed time from the start of charging) becomes longer than a predetermined value. Further, the completion condition may be satisfied when the user gives an instruction to stop charging during charging.

When charging is completed (YES in S25), in S26, the power transmission ECU 150 controls the inverter 120, the AC / DC converter 130, and the like to stop power transmission. Further, the charging relay 400 is turned off by the vehicle ECU 500.

After the start of power transmission, power transmission is performed under condition A while it is determined to be NO in both S22 and S25. If YES is determined in S25 during power transmission under condition A, power transmission is stopped by the processing of S26. If an overcurrent occurs during power transmission under condition A (YES in S22), the process proceeds to S23.

In S23, the power transmission ECU 150 controls the inverter 120, the AC / DC converter 130, and the like to stop power transmission. Then, the power transmission ECU 150 resumes power transmission under the condition B in which the switch 113b (C1 switch) is ON, the switch 113c (C2 switch) is OFF, and the switch 114 (L switch) is OFF (S24). More specifically, the power transmission ECU 150 controls the inverter 120, the AC / DC converter 130, and the like after turning the switches 113b, 113c, and 114 on, off, and off, respectively, from the power transmission coil 101 to the power reception coil 201. Send electricity. After that, the process proceeds to S25 described above.

When power transmission is performed under the condition B by the processing of S24, NO is determined in S21. If it is determined in S21 that NO (power transmission is not performed under condition A), the process proceeds to S31.

In S31, the power transmission ECU 150 determines whether or not power transmission is being performed under the condition B. For example, the power transmission ECU 150 confirms the state of each switch, and if the switches 113b, 113c, and 114 are ON, OFF, and OFF, respectively, it is determined that power transmission is being performed under the condition B. On the other hand, if the states of the switches 113b, 113c, 114 are other than the above, it means that the power transmission is not performed under the condition B. In this embodiment, power transmission is performed under any of the conditions A to C. Therefore, the fact that the power transmission condition being executed is neither condition A nor condition B means that the power transmission condition being executed is condition C.

If it is determined that power transmission is being performed under condition B (YES in S31), the process proceeds to S32. In S32, whether or not the output current of the inverter 120 detected by the power monitoring unit 140 (more specifically, the current sensor) is equal to or higher than a predetermined threshold value Th2 (hereinafter, also simply referred to as “Th2”). , The power transmission ECU 150 determines. Th2 is a threshold value for detecting an overcurrent. Th2 can be obtained by the same method as the threshold value Th1 of S22, for example. Th2 may be the same as or different from Th1. Th2 may be a fixed value or may be variable depending on the situation of the vehicle 2 and the like.

When the output current of the inverter 120 is smaller than Th2 (NO in S32), it is determined that no overcurrent has occurred, and the process proceeds to S25 described above. While the power transmission under the condition B is determined to be NO in both S25 and S32, the power transmission under the condition B is continued. If YES is determined in S25 during power transmission under condition B, power transmission is stopped by the processing of S26. If an overcurrent occurs during power transmission under condition B (YES in S32), the process proceeds to S33.

In S33, the power transmission ECU 150 controls the inverter 120, the AC / DC converter 130, and the like to stop power transmission. Then, the power transmission ECU 150 resumes power transmission under the condition C in which the switch 113b (C1 switch) is OFF, the switch 113c (C2 switch) is OFF, and the switch 114 (L switch) is ON (S34). More specifically, the power transmission ECU 150 controls the inverter 120, the AC / DC converter 130, and the like after turning off, OFF, and ON the switches 113b, 113c, and 114, respectively, from the power transmission coil 101 to the power reception coil 201. Send electricity. After that, the process proceeds to S25 described above.

When power transmission is performed under the condition C by the processing of S34, it is determined as NO in both S21 and S31. If NO is determined in both S21 and S31, the process proceeds to S27.

In S27, whether or not the output current of the inverter 120 detected by the power monitoring unit 140 (more specifically, the current sensor) is equal to or higher than a predetermined threshold value Th3 (hereinafter, also simply referred to as “Th3”). , The power transmission ECU 150 determines. Th3 is a threshold value for detecting an overcurrent. Th3 can be obtained by the same method as the threshold value Th1 of S22, for example. Th3 may be the same as at least one of Th1 and Th2, or may be different from any of Th1 and Th2. Th3 may be a fixed value or may be variable depending on the situation of the vehicle 2 and the like.

The power transmission system 10 is designed so that stable power transmission can be performed (that is, no overcurrent occurs) under any of the conditions A to C. When the coupling coefficient is small, power transmission is stable under condition A, when the coupling coefficient is medium, power transmission is stable under condition B, and when the coupling coefficient is large, power transmission is stable under condition C. Therefore, if an overcurrent occurs during power transmission under any of the conditions A to C, it is considered that some abnormality (such as a failure of an electronic component) has occurred in the power transmission system 10. The fact that power transmission is performed under condition C means that it is determined to be YES in both S22 and S32 (that is, an overcurrent occurs during power transmission in both conditions A and B). Therefore, when an overcurrent occurs during power transmission under condition C (YES in S27), it is determined that an abnormality has occurred in the power transmission system 10, and in S26, the power transmission ECU 150 transmits power without waiting for the completion of charging. Is forcibly stopped. On the other hand, if no overcurrent occurs during power transmission under condition C (NO in S27), the process proceeds to S25 described above.

After the processing of S34 is performed, power transmission is performed under condition C while it is determined to be NO in both S25 and S27. On the other hand, if YES is determined in either S25 or S27, power transmission is stopped by the processing of S26.

When an overcurrent occurs during power transmission under condition C (YES in S27), the vehicle ECU 500 may perform a notification process for notifying the user that an abnormality has occurred in the power transmission system 10. .. Further, the vehicle ECU 500 may record in the storage device that an abnormality has occurred in the power transmission system 10 by changing the value of the diagnosis (self-diagnosis) flag in the storage device from 0 to 1.

In the process of FIG. 16, the coupling coefficient between the power transmission coil 101 and the power reception coil 201 is detected by using the output current of the inverter 120 (S22 and S32). More specifically, when no overcurrent occurs during power transmission under condition A (NO in S22), it is determined that the coupling coefficient is small, and overcurrent occurs during power transmission under condition A (YES in S22). ), And if no overcurrent occurs during power transmission under condition B (NO in S32), it is determined that the coupling coefficient is medium, and overcurrent occurs during power transmission under both conditions A and B. If (YES in S32), it is determined that the coupling coefficient is large. With such a configuration, the coupling coefficient can be easily detected.

Note that to calculate the coupling coefficient in real time from the detection values of various sensors, it is conceivable to precisely control the X _L and X _C of the output frequency in accordance with the calculated coupling coefficient. However, it is difficult to calculate the coupling coefficient with high accuracy, Further, even able to calculate the coupling coefficient with high accuracy, in order to correspond to the coupling coefficient at X _L and X _C high accuracy of the output frequency is high A variable inductor and a variable capacitor are required, which is disadvantageous in terms of cost.

In the process of FIG. 16 above, when the output current of the inverter 120 exceeds a predetermined value during power transmission under condition A (first condition) (YES in S22), the power transmission during execution is stopped (S23). After changing the state of each switch to the state of condition B (second condition), power transmission is restarted (S24). If the output current of the inverter 120 exceeds a predetermined value during power transmission under condition B (YES in S32), the power transmission during execution is stopped (S33), and the state of each switch is changed to condition C (No. 1). After changing to the state of 3 conditions), power transmission is restarted (S34). Such control does not require a semiconductor relay having a high response speed, and a mechanical relay that is cheaper and more easily available than a semiconductor relay can be used. However, the type of each switch is not limited to the mechanical relay. A semiconductor relay may be adopted instead of the mechanical relay.

17, in the contactless power transmission control according to this embodiment, X _L of the output frequency _is a diagram showing the relationship between X _C and the coupling coefficient. 17, line k11 represents a reactance _{X L,} line k12 represents a reactance _{X C.}

Referring to FIG. 17, in a non-contact power transmission control according to this embodiment, depending on the coupling coefficient between the transmitting coil 101 and the power reception coil 201, X _C of the output frequency X _L and _(line k11) Output Frequency ( The line k12) is changed. In the coupling coefficient is small region A (region binding factor is close to 0.1), the output frequency _| X L -X _{C |} is .DELTA.X1 (see FIG. 3). In the coupling coefficient is medium region B (area coupling coefficient is close to 0.3), the output frequency _| X L -X _{C |} is .DELTA.X2 (see FIG. 6). In the coupling coefficient is large region C (region binding factor is close to 0.6), the output frequency _| X L -X _{C |} is DerutaX3 (see FIG. 9). ΔX1, ΔX2, and ΔX3 satisfy the relationship of "ΔX1>ΔX2>ΔX3". Thus, in the non-contact power transmission control according to this embodiment, in accordance with the coupling coefficient increases, the difference between the reactance X _L and reactance X _C at the output frequency of the inverter 120 is reduced.

FIG. 18 is a diagram showing the power transmission efficiency (line k31) in the non-contact power transmission control according to this embodiment in comparison with the power transmission efficiency (line k32) in the non-contact power transmission control according to the comparative example. .. Further, FIG. 19 is a diagram showing the charging power (line k41) in the non-contact power transmission control according to this embodiment in comparison with the charging power (line k42) in the non-contact power transmission control according to the comparative example. In the non-contact power transmission control according to the comparative example, the coupling coefficient is also varied, keeping the reactance X _C and X _L shown in FIG.

As shown by line k31 with reference to FIG. 18, the power transmission efficiency in the non-contact power transmission control according to this embodiment is high in all of the regions A to C. On the other hand, the power transmission efficiency in the non-contact power transmission control according to the comparative example was lowered by increasing the coupling coefficient as shown by the line k32.

As shown by line k41 with reference to FIG. 19, the charging power (that is, the power supplied to the power storage device 300) in the non-contact power transmission control according to this embodiment is in any of the regions A to C. It's getting higher. On the other hand, the charging power in the non-contact power transmission control according to the comparative example decreased as the coupling coefficient increased, as shown by the line k42.

As described above, according to the power transmission device 100 according to this embodiment, it is possible to improve the power transmission efficiency in a wide coupling coefficient range, and by extension, a sufficient amount of charging power can be supplied in a wide coupling coefficient range. It becomes possible to supply power to the power receiving device 200 (further, to the power storage device 300).

In the above embodiment, power transmission is started under condition A (see FIG. 15). However, the present invention is not limited to this, and power transmission may be started under the condition C in S13 of FIG. 15, for example. FIG. 20 is a flowchart showing a processing procedure of power transmission control in a modified example in which power transmission is started under condition C. That is, when power transmission is started under the condition C, for example, the process of FIG. 20 is executed instead of the process of FIG. The process shown in FIG. 20 includes steps S41 and S42 (hereinafter, simply referred to as “S41” and “S42”) in addition to the above-mentioned S22 to S27 and S31 to S33.

With reference to FIG. 20, it is determined whether or not power transmission is performed under condition C in S41, and if power transmission is not performed under condition C (NO in S41), power transmission is performed under condition B in S31. Determine if it is. Then, when the output current of the inverter 120 becomes equal to or higher than a predetermined value (YES in S27) during power transmission under the condition C (YES in S41), the running power transmission is stopped (S23), and the state of each switch is reached. Is set to the state of condition B, and then power transmission is restarted (S24). If the output current of the inverter 120 exceeds a predetermined value (YES in S32) during power transmission under condition B (YES in S31), the power transmission during execution is stopped (S33), and the state of each switch is reached. Is set to the state of condition A, and then power transmission is restarted (S42).

In the process of FIG. 20, when the overcurrent does not occur during the power transmission under the condition C (NO in S27), it is determined that the coupling coefficient is large, and the overcurrent occurs during the power transmission under the condition C (NO). If YES) in S27) and no overcurrent occurs during power transmission under condition B (NO in S32), it is determined that the coupling coefficient is medium, and both conditions B and C are excessive during power transmission. When a current is generated (YES in S32), it is determined that the coupling coefficient is small.

The method for detecting the coupling coefficient is not limited to the method shown in FIGS. 16 and 20, and can be arbitrarily changed. Hereinafter, a modified example of the method for detecting the coupling coefficient will be described with reference to FIG. 21.

FIG. 21 is a flowchart showing a processing procedure of power transmission control executed by the power transmission ECU 150 in the above modification. In this modification, the process of FIG. 21 is executed instead of the process of FIG. The process shown in this flowchart is the same as the process of FIG. 16 except that steps S51 and S52 (hereinafter, simply referred to as “S51” and “S52”) are included instead of S22 and S32.

With reference to FIG. 21, in S51, the power transmission ECU 150 determines whether or not the distance between the coils ΔG is equal to or less than a predetermined threshold value Th11 (hereinafter, also simply referred to as “Th11”). The distance between the coils ΔG can be detected by, for example, a GAP sensor. As the GAP sensor, a known distance measuring sensor (ultrasonic sensor, laser distance measuring sensor, etc.) can be adopted. The same can be said for S52, which will be described later.

Th11 is a threshold value for determining whether or not the coupling coefficient is small, and for example, a value obtained in advance by an experiment or the like is set. The distance between the coils ΔG and the coupling coefficient have an approximately inverse proportional relationship. That is, the larger the distance between the coils ΔG, the smaller the coupling coefficient. Utilizing such a relationship, when the distance between the coils ΔG is larger than Th11 (NO in S51), it can be determined that the coupling coefficient is small.

In S52, the power transmission ECU 150 determines whether or not the distance between the coils ΔG is equal to or less than a predetermined threshold value Th12 (hereinafter, also simply referred to as “Th12”). Th12 is a threshold value for determining whether or not the coupling coefficient is large, and for example, a value obtained in advance by an experiment or the like is set. Th12 is smaller than Th11. When the distance between the coils ΔG is Th12 or less (YES in S52), it can be determined that the coupling coefficient is large. Further, when the distance between the coils ΔG is more than Th12 and Th11 or less (NO in S52), it can be determined that the coupling coefficient is medium.

Each configuration of the capacitive reactance adjusting unit 110C and the inductive reactance adjusting unit 110L is not limited to the configuration shown in FIG. 2, and may be changed to any of the configurations shown in FIGS. 22 to 24 described below, for example. ..

With reference to FIG. 22, the inductive reactance adjusting unit 110L may be a variable inductor L20 connected in series with the LC resonance unit R1 (FIG. 2). The capacitive reactance adjusting unit 110C may be a variable capacitor C20 connected in parallel to the LC resonance unit R1 (FIG. 2). The reactance between the inverter 120 and the capacitive reactance adjusting unit 110C is inductive reactance by the inductor (variable inductor L20) connected in series with the LC resonance unit R1.

The variable inductor L20 includes, for example, a magnetic material (core) and an exciting winding, and is configured such that the inductance changes continuously according to a control signal (more specifically, the current of the exciting winding) from the power transmission ECU 150. Will be done. The inductance of the variable inductor L20 can be adjusted to an arbitrary value by passing a DC superimposed current through the exciting winding to change the magnetic permeability. The variable inductor is not limited to this, and any variable inductor can be selected and adopted from various known variable inductors.

The variable capacitor C20 is configured so that the capacitance continuously changes according to the control signal from the power transmission ECU 150. As the variable capacitor C20, for example, an air gap capacitor using an air as a dielectric can be adopted. The variable capacitor is not limited to this, and any variable capacitor can be selected and adopted from various known variable capacitors. The same can be said for the variable capacitor C21 described later.

With reference to FIG. 23, the inductive reactance adjusting unit 110L may be configured to include a coil L21 and a variable capacitor C21 connected in series with the LC resonance unit R1 (FIG. 2). The inductance _{L 21} of the coil L21, the capacitance of the variable capacitor C21 is expressed as _{C 21,} the reactance _{X L} can be expressed by Equation (10). In equation (10), "ωL ₂₁ " is larger than "1 / ωC _21".

With reference to FIG. 24, the inductive reactance adjusting unit 110L may include a coil L22, a capacitor C22, and a switch 115 connected in series with the LC resonance unit R1 (FIG. 2). The switch 115 is connected in parallel to the capacitor C22. When the switch 115 is turned on (closed), the terminals of the capacitor C22 are short-circuited. Reactance _{X L} is changed by the state of the switch 115 (ON / OFF).

Inductive reactance between the inverter 120 and the capacitive reactance adjuster 110C (the reactance X _L) may be fixed in the circuit shown in FIG. Figure 25 is a diagram showing a modified example of the reactance X _L to a fixed. With reference to FIG. 25, a coil L23 (an inductor connected in series with the LC resonance unit R1) may be used instead of the inductive reactance adjusting unit 110L (FIG. 2) used in the above embodiment. In this configuration, the coupling coefficient by approximating the X _C to X _{L (fixed} value) in accordance with increase of the output frequency in accordance with the coupling coefficient is increased | can be reduced _| X L _-X C.

In the above embodiment, the magnitude of the coupling coefficient is divided into three categories (small, medium, and large), but the number of categories is arbitrary as long as it is plural, for example, the magnitude of the coupling coefficient is four or more. It may be divided into categories.

The embodiments disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present invention is shown by the scope of claims rather than the description of the embodiments described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Charging equipment, 2 vehicles, 10 power transmission systems, 100 power transmission devices, 101 power transmission coils, 102, 202, 203, 206a, 206b, 207, C11a, C11b, C11c, C22 capacitors, 110 filter circuits, 110C capacitive reactorance adjustment. Unit, 110L Inductive Reactance Adjustment Unit, 113b, 113c, 114, 115 Switch, 120 Inverter, 130 AC / DC Converter, 140 Power Monitoring Unit, 150 Transmission ECU, 160, 600 Communication Unit, 200 Power Receiving Device, 201 Power Receiving Coil, 204 inductor, 205 rectifier circuit, 300 power storage device, 310 battery monitoring unit, 400 charging relay, 500 vehicle ECU, 700 AC power supply, C20, C21 variable capacitor, L11a, L11b, L21, L22, L23 coil, L20 variable inductor, R1 , R2 LC resonance part.

Claims (1)

A non-contact power transmission device that transmits power from the power transmission coil to the power reception coil of the power receiving device in a non-contact manner.
An inverter that converts input power to AC power of a predetermined frequency and outputs it,
An LC resonance section provided on the output side of the inverter and configured by connecting the power transmission coil and the capacitor in series.
A capacitive reactance adjusting unit configured so that the capacitive reactance between the terminals of the LC resonance unit can be changed by an element connected in parallel to the LC resonance unit.
A control unit that controls the capacitive reactance adjusting unit is provided.
The reactance between the inverter and the capacitive reactance adjusting unit is an inductive reactance due to an inductor connected in series with the LC resonance unit.
The control unit is a non-contact power transmission device that reduces the difference between the inductive reactance and the capacitive reactance at the predetermined frequency as the coupling coefficient between the power transmission coil and the power receiving coil increases.

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