JP6686922B2 - Power receiving device and power transmitting device - Google Patents

Description

  The present disclosure relates to a power receiving device and a power transmitting device, and particularly to a technique for determining whether or not non-contact power transmission is possible according to a parameter having a correlation with a power receiving efficiency of the power receiving device.

  A contactless power transmission system in which power is transmitted from a power transmitting device to a power receiving device in a contactless manner is known (see Patent Documents 1 to 6). The power transmission device includes a power transmission coil, and the power reception device includes a power reception coil.

  In the contactless power transmission system disclosed in JP-A-2005-144529 (Patent Document 1), whether power transmission from the power transmission device to the power reception device is possible after the power reception device is aligned with the power transmission device. Is determined. Specifically, whether or not power transmission from the power transmitting device to the power receiving device is possible is determined by whether or not the relative position of the power receiving device with respect to the power transmitting device satisfies a predetermined condition (see Patent Document 1).

JP, 2005-144529, A JP, 2013-154815, A JP, 2013-146154, A JP, 2013-146148, A JP, 2013-110822, A JP, 2013-126327, A

  When non-contact power transmission from the power transmitting device to the power receiving device is started, some elements included in the power transmitting device and the power receiving device generate heat, and the characteristics of the elements change. Therefore, even if it is determined that the power receiving device can receive sufficient power before the start of power transmission, it is possible that the power receiving device may not be able to receive sufficient power after the start of power transmission due to changes in element characteristics after the start of power transmission. To be In the above-mentioned Patent Document 1, no particular consideration is given to such changes in element characteristics after the start of power transmission.

  The present disclosure has been made to solve such a problem, and an object thereof is to prevent the power receiving device from being unable to sufficiently receive power after the start of non-contact power transmission from the power transmitting device to the power receiving device. Is to provide a technology capable of reducing

  The power receiving device of the present disclosure includes a power receiving coil, a power storage device, and a control device. The power reception coil is configured to receive power from the power transmission device in a contactless manner. The power storage device is configured to store the electric power received by the power receiving coil. The control device is configured to determine whether or not power reception by the power reception coil is possible, depending on whether or not a parameter having a correlation with the power reception efficiency by the power reception coil is within a predetermined range. The control device corrects the predetermined range in accordance with at least one of the time required to charge the power storage device using the electric power received by the power receiving coil and the outside air temperature.

  Further, the power transmission device of the present disclosure includes a power transmission coil and a control device. The power transmission coil is configured to transmit power to the power receiving device in a contactless manner. The control device is configured to determine whether or not power transmission by the power transmission coil can be performed depending on whether or not a parameter having a correlation with the power reception efficiency of the power reception device falls within a predetermined range. The power receiving device includes a power receiving coil and a power storage device. The power receiving coil is configured to receive power from the power transmitting coil in a non-contact manner. The power storage device is configured to store the electric power received by the power receiving coil. The control device corrects the predetermined range according to at least one of the time required to charge the power storage device using the electric power received by the power receiving coil and the outside air temperature.

  When the time required to charge the power storage device is long or the outside air temperature is high, the temperature of the element included in the power transmission device and the power reception device is likely to rise during non-contact power transmission, and the element characteristics are likely to change. In these power receiving devices and power transmitting devices, since the above predetermined range is modified according to at least one of the time required to charge the power storage device and the outside temperature, the characteristics of the elements included in the power transmitting device and the power receiving device during non-contact power transmission. The possibility of non-contact power transmission is determined after considering the change. Therefore, according to the power receiving device and the power transmitting device, it is possible to reduce the possibility that the power receiving device cannot sufficiently receive power after the start of the non-contact power transmission.

  According to the present disclosure, it is possible to provide a technique capable of reducing the possibility that the power receiving device cannot sufficiently receive power after the power transmission from the power transmitting device to the power receiving device is started in a non-contact manner.

It is a block diagram of a non-contact electric power transmission system. It is a figure which shows the time required for charge of a power storage device, the outside temperature, and the relationship of the change degree of the element characteristic during charge. It is a figure which shows the relationship between the change degree of the element characteristic during charge of an electrical storage apparatus, and the margin for correcting the said predetermined range. It is a flowchart which shows the process sequence of the propriety determination of non-contact electric power transmission. 7 is a flowchart showing a processing procedure for obtaining a degree of change in element characteristics during non-contact power transmission.

  Hereinafter, embodiments will be described in detail with reference to the drawings. It should be noted that the same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

[Embodiment 1]
(Configuration of contactless power transmission system)
FIG. 1 is a configuration diagram of a contactless power transmission system 1 to which a vehicle 100 according to the present embodiment is applied. Referring to FIG. 1, contactless power transmission system 1 includes a vehicle 100 and a power transmission device 200. Electric power is transmitted between the vehicle 100 and the power transmission device 200 in a non-contact manner.

  Power transmission device 200 includes a power transmission unit 210, a communication unit 240, and a control device 250. Power transmission device 200 transmits AC power received from system power supply 300 to vehicle 100 via power transmission unit 210.

  Power transmission unit 210 includes, for example, an inverter, a power transmission coil, and a capacitor (all not shown). In the power transmission unit 210, the power transmission coil and the capacitor are designed to resonate at the transmission frequency in non-contact power transmission. The power transmission coil forms a magnetic field by receiving the transmission power generated by the inverter based on the AC power of the system power supply 300, and transmits the power to the power reception coil of the power reception unit 110 in a non-contact manner through the formed magnetic field. The number of turns of the conductive wire in the power transmission coil is appropriately designed so that the Q value (for example, Q ≧ 100) and the coupling coefficient κ are large. Further, the element characteristics (for example, L (inductance) or C (capacitance)) of the power transmission coil and the capacitor change depending on the temperature.

  The communication unit 240 can communicate with the communication unit 120 (described later) of the vehicle 100. The communication unit 240 is composed of, for example, a communication module conforming to a wireless LAN standard such as IEEE (Institute of Electrical and Electronic Engineers) 802.11.

  The control device 250 has a CPU (Central Processing Unit) and a memory (not shown) built therein, and each device of the power transmission device 200 (the power transmission unit 210, based on information stored in the memory or information from each sensor (not shown)). Communication unit 240, etc.).

  Control device 250 controls power transmission unit 210 to perform power transmission, for example. Control device 250 can control power transmission unit 210 to transmit weak power in addition to power transmission for charging power storage device 150. Transmission of weak electric power is performed to determine whether or not vehicle 100 is stopped at a position where it can sufficiently receive electric power. In the vehicle 100, it is determined whether or not contactless power transmission is possible, depending on the power reception status of weak power.

  Vehicle 100 includes a power receiving unit 110, a communication unit 120, a power storage device 150, a temperature sensor 160, and an ECU (Electronic Control Unit) 140. In vehicle 100, electric power received contactlessly from power transmission device 200 is stored in power storage device 150. Then, in vehicle 100, the traveling driving force of vehicle 100 is generated based on the electric power stored in power storage device 150.

  Power reception unit 110 includes a power reception coil and a capacitor (both not shown). In the power receiving unit 110, the power receiving coil and the capacitor are designed to resonate at the power transmission frequency in non-contact power transmission. The power reception coil receives power from the power transmission coil of the power transmission unit 210 in a non-contact manner. The electric power (AC) received by the power receiving unit 110 is converted into DC power, and the voltage is converted into a desired voltage and then stored in the power storage device 150. The number of turns of the conductive wire in the power receiving coil is appropriately designed so that the Q value (for example, Q ≧ 100) and the coupling coefficient κ are large. Further, the element characteristics (for example, L (inductance) or C (capacitance)) of the power receiving coil and the capacitor change depending on the temperature. In the present embodiment, the possibility of non-contact power transmission is determined in consideration of changes in element characteristics due to temperature. Details will be described later.

  The communication unit 120 can communicate with the communication unit 240 of the power transmission device 200. The communication unit 120 receives, for example, information indicating the magnitude of the power transmitted by the power transmission unit 210 (including the weak power described above). The communication unit 120 is composed of, for example, a communication module compliant with a wireless LAN standard such as IEEE 802.11.

  Power storage device 150 is a power storage element configured to be chargeable and dischargeable. Power storage device 150 is configured to include, for example, a secondary battery such as a lithium-ion battery, a nickel hydrogen battery or a lead storage battery, or a power storage element such as an electric double layer capacitor.

  The temperature sensor 160 is configured to detect the outside air temperature. The detection result of the temperature sensor 160 is output to the ECU 140.

  The ECU 140 has a CPU and a memory (not shown) built therein, and controls each device (the power receiving unit 110, the communication unit 120, etc.) of the vehicle 100 based on the information stored in the memory and the information from each sensor (not shown). .

  The ECU 140 determines whether or not contactless power transmission is possible, for example, according to the above-described weak power reception status. Specifically, the ECU 140 acquires, via the communication unit 120, information indicating the magnitude of the weak power transmitted by the power transmission unit 210. Then, ECU 140 has a ratio of the weak power actually received by power reception unit 110 to the weak power transmitted by power transmission unit 210 (power reception power / transmission power), that is, power reception efficiency (hereinafter, also referred to as “predetermined parameter”). ) Is calculated. The ECU 140 determines whether or not non-contact power transmission is possible depending on whether or not a predetermined parameter satisfies a predetermined condition. The method for determining whether or not the contactless power transmission is possible will be described later in detail. The magnitude of the power actually received by the power receiving unit 110 is determined by the output of a voltage sensor that detects the power receiving voltage of the power receiving unit 110 and a current sensor (not shown) that detects the power receiving current of the power receiving unit 110. Is calculated based on.

(Change in circuit characteristics during non-contact power transmission)
When non-contact power transmission from power transmission device 200 to vehicle 100 is started, some elements (for example, a coil and a capacitor) included in power transmission section 210 and power reception section 110 generate heat, and the characteristics of the elements change. . As the element characteristics change, the electric circuit characteristics (electric circuit constants) of the resonance circuits included in the power transmission unit 210 and the power reception unit 110 change. Therefore, even if it is determined that the power receiving unit 110 can receive sufficient power before the start of the contactless power transmission, the change in the electric circuit characteristics after the start of the contactless power transmission causes the contactless power transmission to be stopped. The power receiving unit 110 may not be able to receive sufficient power after the start.

  When the time required to charge power storage device 150 is long or the outside air temperature is high, the temperatures of the elements included in power transmission unit 210 and power reception unit 110 are likely to rise and the element characteristics are likely to change. Therefore, when the time required to charge power storage device 150 is long or the outside air temperature is high, the power receiving unit 110 cannot sufficiently receive power after the start of contactless power transfer by making the determination as to whether or not contactless power transfer is strict. Possibility can be reduced.

  In vehicle 100 according to the present embodiment, ECU 140 determines whether or not non-contact power transmission is possible (whether or not power reception unit 110 is able to receive power), according to whether or not the above-described predetermined parameter (power reception efficiency) falls within a predetermined range. . Then, ECU 140 corrects the predetermined range in accordance with at least one of the time required to charge power storage device 150 using the electric power received by the power receiving coil of power receiving unit 110 and the outside temperature. According to this vehicle 100, the characteristic change of the elements included in the power reception unit 110 and the power transmission unit 210 is considered in the determination of whether or not the contactless power transmission is performed, so that the power reception unit 110 can sufficiently receive the power after the start of the contactless power transmission. The possibility of disappearing can be reduced.

  An example of a method of correcting the predetermined range will be described next. The default value of the lower limit value in the predetermined range is Pmin, and the default value of the upper limit value in the predetermined range is Pmax. In the present embodiment, the degree of change (α1) in the element characteristics during charging of power storage device 150 is determined based on the time (Tchg) required to charge power storage device 150 and the outside air temperature (Tamb). Then, the margin (β1) for correcting the lower limit value and the upper limit value is obtained based on α1. The corrected lower limit value of the predetermined range is Pmin + β1, and the corrected upper limit value of the predetermined range is Pmax−β1.

  FIG. 2 is a diagram showing the relationship between the time (Tchg) required to charge the power storage device 150, the outside air temperature (Tamb), and the degree of change (α1) in the element characteristics during charging of the power storage device 150. Referring to FIG. 2, the horizontal axis represents Tchg and the vertical axis represents α1. Each of the straight lines L1, L2, and L3 indicates α1 with respect to Tchg at different outside temperatures, and the outside temperatures are high in the order of the straight lines L1, L2, and L3. As shown in FIG. 2, α1 increases as the time required to charge power storage device 150 increases and the outside air temperature increases.

  FIG. 3 is a diagram showing the relationship between the degree of change (α1) in the element characteristics during charging of power storage device 150 and the margin (β1) for correcting the predetermined range. Referring to FIG. 3, the horizontal axis represents α1 and the vertical axis represents β1. As shown in FIG. 3, as α1 becomes larger, β1 becomes exponentially larger.

  The data showing the relationship shown in FIG. 2 and FIG. 3 is stored in the internal memory of the ECU 140, for example. ECU 140 calculates the SOC (State Of Charge) of power storage device 150, and predicts the time required to charge power storage device 150 based on the calculated SOC and the power received by power receiving unit 110 (target value). The received power (target value) by the power receiving unit 110 is stored in the internal memory of the ECU 140. The ECU 140 calculates α1 based on the data indicating the relationship shown in FIG. 2, the predicted charging time, and the output of the temperature sensor 160. The ECU 140 calculates β1 based on the data indicating the relationship shown in FIG. 3 and the calculated α1. Then, ECU 140 corrects the predetermined range based on the obtained β1, and determines whether or not non-contact power transmission is possible based on the corrected predetermined range. Thus, according to vehicle 100, the characteristic change of the elements included in power reception unit 110 and power transmission unit 210 is taken into consideration when determining whether or not contactless power transmission is performed. It is possible to reduce the possibility that power cannot be received.

(Processing procedure for determining whether contactless power transmission is possible)
FIG. 4 is a flowchart showing a processing procedure for determining whether or not contactless power transmission is possible. The process shown in this flowchart is executed after the vehicle 100 stops on the power transmission device 200.

  Referring to FIG. 4, ECU 140 obtains the degree of change (α1) in the element characteristics included in power reception unit 110 and power transmission unit 210 during non-contact power transmission (step S100). The method of estimating α1 will be described later in detail. The ECU 140 obtains the margin β1 based on the obtained α1 stored in the internal memory and indicating the relationship shown in FIG. 3 (step S110). The ECU 140 corrects the predetermined range based on the obtained margin β1 (step S120). Specifically, ECU 140 corrects the lower limit value of the predetermined range to Pmin (default lower limit value) + β1, and the upper limit value of the predetermined range to Pmax (default upper limit value) −β1.

  After that, the ECU 140 controls the communication unit 120 to transmit an instruction to start transmitting weak power to the power transmission device 200 (step S130). As a result, information indicating the magnitude of the weak power transmitted by the power transmitting apparatus 200 is received from the power transmitting apparatus 200 via the communication unit 120, and the power transmitting apparatus 200 starts transmitting the weak power.

  The ECU 140 detects the power received by the power receiving unit 110 and calculates the power receiving efficiency (predetermined parameter) by the power receiving unit 110 (step S140). Specifically, ECU 140 calculates the ratio of the weak power actually received by power reception unit 110 to the weak power transmitted by power transmission unit 210 (power reception power / transmission power).

  The ECU 140 determines whether the calculated predetermined parameter is equal to or higher than the corrected lower limit value (Pmin + β1) of the predetermined range and is equal to or lower than the corrected upper limit value (Pmax−β1) of the predetermined range (the predetermined condition is satisfied). Is determined (step S150). When it is determined that the predetermined condition is satisfied (YES in step S150), ECU 140 determines that non-contact power transmission is possible (power reception by power reception unit 110 is possible) (step S160). On the other hand, if it is determined that the predetermined condition is not satisfied (NO in step S150), ECU 140 determines that non-contact power transmission is impossible (power reception by power reception unit 110 is impossible) (step S170).

  FIG. 5 is a flowchart showing a processing procedure for obtaining the degree of change (α1) in element characteristics during non-contact power transmission. The processing shown in this flowchart is executed at the timing of step S100 in FIG.

  Referring to FIG. 5, ECU 140 estimates the time required for power storage device 150 to be fully charged (step S200). Specifically, ECU 140 calculates the SOC of power storage device 150, and based on the calculated SOC and the power received by power reception unit 110 (target value) during charging of power storage device 150, power storage device 150 is fully charged. Predict the time it will take to become. The ECU 140 acquires the detection result of the temperature sensor 160 (step S210).

  The ECU 140 uses the data indicating the relationship shown in FIG. 2 stored in the internal memory, the estimated charging time, and the ambient temperature (the detection result of the temperature sensor 160) to determine the element characteristics during non-contact power transmission. Change degree (α1) is obtained (step S220).

  As described above, in vehicle 100 according to the present embodiment, ECU 140 determines whether or not contactless power transmission is possible (power reception by power reception unit 110) according to whether or not the above-described predetermined parameter (power reception efficiency) falls within a predetermined range. Yes / No) is determined. Then, ECU 140 corrects the predetermined range in accordance with at least one of the time required to charge power storage device 150 and the outside air temperature. According to this vehicle 100, it is possible to reduce the possibility that the power receiving unit 110 cannot sufficiently receive power after the start of non-contact power transmission.

[Second Embodiment]
In the above-described first embodiment, the possibility of non-contact power transmission is determined on the vehicle 100 side. In the second embodiment, the possibility of non-contact power transmission is determined on the power transmission device 200 side. In the following, points different from those of the first embodiment will be mainly described, and description of the same parts as those of the first embodiment will not be repeated.

  Referring again to FIG. 1, non-contact power transmission system 1A to which power transmission device 200A according to the second embodiment is applied includes vehicle 100A and power transmission device 200A. Vehicle 100A includes an ECU 140A, and power transmission device 200A includes a control device 250A.

  The ECU 140A has a built-in CPU and memory (not shown), and controls each device (power receiving unit 110, communication unit 120, etc.) of the vehicle 100A based on information stored in the memory and information from each sensor (not shown). . ECU 140A does not store data indicating the relationship shown in FIGS. 2 and 3 in the internal memory, unlike ECU 140 in the first embodiment. ECU 140A is configured to be able to control communication unit 120 to transmit data indicating the SOC of power storage device 150, data indicating the received power of power reception unit 110, and the detection result of temperature sensor 160 to power transmission device 200, for example. ing.

  The control device 250A includes a CPU and a memory (not shown), and each device (the power transmission unit 210, the communication unit 240, etc.) of the power transmission device 200A based on the information stored in the memory and the information from each sensor (not shown). To control. The control device 250A stores data indicating the relationships shown in FIGS. 2 and 3 in the internal memory. Control device 250A is configured to be able to acquire data indicating the SOC of power storage device 150, data indicating the received power of power reception unit 110, and the detection result of temperature sensor 160 from vehicle 100 via communication unit 240. .

  The control device 250A is configured to calculate the power reception efficiency (power reception power / power transmission power) based on the power reception power of the power reception unit 110 and the power transmission power of the power transmission unit 210, and the power reception efficiency (predetermined parameter) is within a predetermined range. If the power receiving efficiency is out of the predetermined range, it is determined that the non-contact power transmission is impossible.

  After vehicle 100A stops on power transmission device 200A, control device 250A receives data indicating SOC of power storage device 150 obtained from vehicle 100 via communication unit 240, and power reception unit 110 during charging of power storage device 150. The time required for charging the power storage device 150 is estimated according to the data indicating the received power (target value). Then, the control device 250A receives the detection result of the temperature sensor 160 acquired from the vehicle 100 via the communication unit 240, the estimated charging time, and the data indicating the relationship shown in FIG. 2 stored in the internal memory. Based on the above, the degree of change (α1) in the element characteristics during charging of the power storage device 150 is obtained.

  The control device 250A sets a margin β1 for correcting a predetermined range used for determining whether or not contactless power transmission is possible, based on the obtained α1 and the data indicating the relationship shown in FIG. 3 stored in the internal memory. Ask. The controller 250A corrects the upper limit value and the lower limit value of the predetermined range according to the obtained β1. After that, the control device 250A controls the power transmission unit 210 to transmit the weak power. 250 A of control apparatuses acquire the information which shows the magnitude | size of the received electric power of weak electric power from the vehicle 100 via the communication part 240, and calculate a power receiving efficiency based on the acquired information. Control device 250A determines whether non-contact power transmission is possible by determining whether the calculated power reception efficiency is included in the corrected predetermined range.

  As described above, control device 250A determines whether power transmission by power transmission unit 210 is possible or not, depending on whether the power reception efficiency (predetermined parameter) by power reception unit 110 is within a predetermined range. Then, control device 250A corrects the predetermined range in accordance with at least one of the time required to charge power storage device 150 and the outside air temperature. Thereby, according to the power transmission device 200, the characteristic change of the elements included in the power reception unit 110 and the power transmission unit 210 is taken into consideration in the determination as to whether or not the non-contact power transmission is performed. It is possible to reduce the possibility that power cannot be received.

  In the first and second embodiments, the power reception efficiency is used as the predetermined parameter. However, the predetermined parameter is not necessarily limited to the power reception efficiency. For example, in the contactless power transmission system 1, 1A in which the power transmission unit 210 is controlled such that the target power is received by the power reception unit 110, the current value of the power transmission coil of the power transmission unit 210 may be set as the predetermined parameter, The current value of the inverter of the power transmission unit 210 may be used as the predetermined parameter. Further, the coupling coefficient between the power receiving coil of power receiving section 110 and the power transmitting coil of power transmitting section 210 may be estimated, and the estimated coupling coefficient may be used as the predetermined parameter. That is, the predetermined parameter may be a parameter having a correlation with the power receiving efficiency of the power receiving units 110 and 110A.

  Further, in the first and second embodiments, the predetermined range for determining the possibility of non-contact power transmission is modified by referring to both the charging time of power storage device 150 and the outside temperature. However, both the charging time and the outside air temperature do not necessarily have to be used to correct the predetermined range, and only one of the charging time and the outside air temperature may be used, for example. Even in this case, as compared with the case where the predetermined range is not corrected at all, the characteristics of the elements included in the power transmission unit 210 and the power reception unit 110 are taken into consideration, so that the vehicles 100 and 100A are in the middle of non-contact power transmission. It is possible to reduce the possibility that the power cannot be sufficiently received.

  The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

  1 Non-contact power transmission system, 100 vehicle, 110 power receiving unit, 115 power receiving coil, 120, 240 communication unit, 140 ECU, 150 power storage device, 160 temperature sensor, 200 power transmission device, 210 power transmission unit, 215 power transmission coil, 220 imaging device , 250 controller, 300 power supply.

Claims (4)

A power receiving coil configured to receive power from the power transmitting device in a non-contact manner,
A power storage device configured to store the electric power received by the power receiving coil,
According to whether or not a parameter having a correlation with the power reception efficiency by the power receiving coil is within a predetermined range, a control device configured to determine whether or not power reception by the power receiving coil is possible,
The power receiving device, wherein the control device corrects the predetermined range in accordance with at least one of a time required to charge the power storage device using the electric power received by the power receiving coil and an outside air temperature. The power reception device according to claim 1, wherein the control device corrects the predetermined range in consideration of a change in characteristics of the power reception device and the power transmission device due to a rise in temperature. A power transmission coil configured to transmit power to a power receiving device in a contactless manner;
A control device configured to determine whether or not power transmission by the power transmission coil is possible depending on whether or not a parameter having a correlation with the power reception efficiency by the power receiving device falls within a predetermined range,
The power receiving device,
A power receiving coil configured to receive power from the power transmitting coil in a non-contact manner,
A power storage device configured to store the power received by the power receiving coil,
The control device corrects the predetermined range according to at least one of a time required to charge the power storage device using the electric power received by the power receiving coil and an outside air temperature. The power transmission device according to claim 3, wherein the control device corrects the predetermined range in consideration of a change in characteristics of the power reception device and the power transmission device due to a rise in temperature.

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