vehicle

Abstract

To suppress the degradation of a secondary battery when charging the secondary battery in the time of non-contact power reception.SOLUTION: A vehicle comprises: a power reception device 20 which can receive power in a non-contact manner from a power transmission device 10; a capacitor 351 which stores the power received by the power reception device 20; a secondary battery 353; a drive device which generates a driving force with the power from the secondary battery 353; a charge switch 352 which connects the capacitor 351 to the secondary battery 353; and a charge ECU 360 which controls the power reception device 20 and the charge switch 352. The charge ECU 360 controls the charge switch 352 to separate the secondary battery 353 from the capacitor 351 when the power is received from the power transmission device 10 by the power reception device 20, and controls the charge switch 352 to connect the secondary battery 353 to the capacitor 351 when the power reception device 20 stops power reception.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to monitoring of a vehicle, and more particularly to a vehicle equipped with a power receiving device that receives power from a power transmitting device. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2020-10451 (Patent Document 1) discloses a vehicle capable of contactlessly receiving power from a power transmission unit buried in the road surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-10451 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a vehicle receives power from the road surface or the like in a non-contact manner, the mutual conductance between the power transmitting device and the power receiving device increases, and the coupling coefficient between the power transmitting device and the power receiving device increases, which may temporarily increase the received power. As a result, when charging a secondary battery with the received power, a pulsation occurs at which the secondary battery is supplied with power that greatly exceeds the gravitational power available to the secondary battery, and this may damage the secondary battery.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to suppress damage to a secondary battery when contactless power reception is performed from the road surface or the like. [Means for solving the problem]

[0006] A vehicle according to the present disclosure includes a capacitor that stores electric power received by a power receiving device, a secondary battery, a drive device that generates driving force using electric power from the secondary battery, a connection device that connects the capacitor and the secondary battery, and a control device that controls the power receiving device and the connection device. The control device is configured to control the connection device to disconnect the secondary battery and the capacitor when the power receiving device receives electric power from a power transmitting device, and to control the connection device to connect the secondary battery and the capacitor when the power receiving device stops receiving electric power. Effect of the Invention

[0007] According to the vehicle of the present disclosure, when the power receiving device stops receiving power, the control device controls the connection device to connect the secondary battery and the capacitor and transfer power from the capacitor to the secondary battery. In this way, when the secondary battery is being charged, it is possible to prevent damage to the secondary battery caused by excessive power due to contactless power reception. [Brief description of the drawings]

[0008] [Figure 1] 1 is an external view of a power transmission system according to an embodiment of the present invention. [Diagram 2] 1 is an overall configuration diagram of a power transmitting device 10 and a power receiving device 20. FIG. [Diagram 3] 5 is a waveform diagram for explaining the control state of the power receiving relay and the charging switch. FIG. [Figure 4] 4 is a flowchart for illustrating a control executed during external charging. [Diagram 5] FIG. 11 is a diagram for explaining a first application example. [Figure 6] FIG. 11 is a diagram for explaining a second application example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated. Hereinafter, an electronic control unit (Electronic Control Unit) will also be referred to as "ECU."

[0010] 1 is an external view of a power transmission system according to the present embodiment. The power transmission system includes a vehicle 1 and a power transmission device 10. The vehicle 1 includes a power receiving device 20, a power storage device 350, and a drive device 390. The power receiving device 20 is provided on the bottom surface of the vehicle 1, for example, on the underside (road surface side) of the power storage device 350 installed on the bottom surface of the vehicle 1. The vehicle 1 is configured to drive drive wheels by the drive device 390 that uses power supplied from the power transmission device 10 and stored in the power storage device 350.

[0011] The power transmitting device 10 receives power from an AC power source 100 (for example, a commercial power system). The power transmitting device 10 is installed on the ground. The power transmitting device 10 is configured to transmit power to the power receiving device 20 of the vehicle 1 in a non-contact manner through a magnetic field when the power receiving device 20 faces the power transmitting device 10.

[0012] FIG. 2 is a diagram showing the overall configuration of the power transmitting device 10 and the power receiving device 20. As shown in FIG. The power transmitting device 10 includes a power transmitting unit 11, a power supply ECU 250, and a communication unit 260. The power transmitting unit 11 includes a power factor correction (PFC) circuit 210, an inverter 220, a filter circuit 230, a power transmitting unit 240, a voltage sensor 270, and current sensors 272 and 274.

[0013] The power receiving device 20 includes a power receiving unit 21, a power receiving relay 340, a power storage device 350, a charging ECU 360, and a communication unit 370. The power receiving unit 21 includes a power receiving unit 310, a filter circuit 320, a rectification unit 330, a voltage sensor 380, and a current sensor 382.

[0014] In this power transmission system, in the power transmitting device 10, power received from an AC power source 100 such as a commercial power system is rectified and boosted by a PFC circuit 210 and supplied to an inverter 220. The inverter 220 converts the power rectified by the PFC circuit 210 into AC power and outputs it. The AC power output from the inverter 220 is supplied to a power transmitting unit 240 via a filter circuit 230. Each of the power transmitting unit 240 and the power receiving unit 310 includes a resonant circuit and is designed to resonate at the frequency of the transmitted power.

[0015] When AC power is supplied from inverter 220 to power transmitting unit 240 through filter circuit 230, energy (power) moves from power transmitting unit 240 to power receiving unit 310 through a magnetic field formed between a power transmitting coil (not shown) included in power transmitting unit 240 and a power receiving coil (not shown) included in power receiving unit 310. The energy (power) moved to power receiving unit 310 is supplied to power storage device 350 through filter circuit 320 and rectifier unit 330.

[0016] The power storage device 350 includes a capacitor 351 that stores the power received by the power receiving device, a charging switch 352, and a secondary battery 353. The secondary battery 353 is a rechargeable DC power source, and is formed of, for example, a lithium ion battery or a nickel metal hydride battery. The capacitor 351 is, for example, an electric double layer capacitor having a larger allowable received power than the secondary battery 353. The power receiving relay 340 is provided between the rectifier 330 and the capacitor 351.

[0017] The power receiving relay 340 is controlled to an on state (conductive state) during external power reception in which the power receiving unit 21 can receive power from the power transmitting unit 11. When the power receiving unit 21 does not receive power from the power transmitting unit 11, the power receiving relay 340 is controlled to an off state (non-conductive state).

[0018] Voltage sensor 270 detects the output voltage of inverter 220. Current sensor 272 detects the output current of inverter 220. Current sensor 274 detects the current flowing through power transmitting unit 240. These sensors each output the detection results to power supply ECU 250.

[0019] The power supply ECU 250 includes a CPU (Central Processing Unit), a memory, input / output ports for inputting and outputting various signals, and the like (none of which are shown), and receives signals from the above-mentioned sensors and the like, and controls various devices in the power transmitting device 10. For example, the power supply ECU 250 performs switching control of the PFC circuit 210 and the inverter 220 when power is transmitted from the power transmitting device 10 to the power receiving device 20. Note that the various controls are not limited to being processed by software, and can also be processed by dedicated hardware (electronic circuits).

[0020] The communication unit 260 is configured to wirelessly communicate with the communication unit 370 of the power receiving device 20. For example, when an abnormality is detected in the power transmitting device 10, the communication unit 260 outputs an abnormality signal to the power receiving device 20 and receives the abnormality signal from the power receiving device 20.

[0021] A voltage sensor 380 provided in the power receiving device 20 detects the output voltage of the rectification unit 330. A current sensor 382 detects the output current from the rectification unit 330. The voltage sensor 380 and the current sensor 382 may be provided between the power receiving unit 310 and the rectification unit 330 (for example, between the filter circuit 320 and the rectification unit 330). These sensors each output the detection results to the charging ECU 360.

[0022] The charging ECU 360 includes a CPU, a memory, an input / output port, etc. (none of which are shown), receives signals from the above-mentioned sensors, etc., and controls various devices in the power receiving device 20. The various controls are not limited to processing by software, and can also be processed by dedicated hardware (electronic circuitry).

[0023] When the power receiving unit 21 receives power from the power transmitting unit 11, the charging ECU 360 controls the charging switch 352 to disconnect the secondary battery 353 and the capacitor 351. On the other hand, when the power receiving unit 21 stops receiving power, the charging ECU 360 is configured to control the charging switch 352 to connect the secondary battery 353 and the capacitor 351.

[0024] FIG. 3 is a waveform diagram for explaining the control state of the power receiving relay and the charging switch. At time t1, the power receiving relay 340 is turned on when the power receiving device 20 becomes capable of receiving power transmitted from the power transmitting device 10. At this stage, the charging switch 352 is set to the off state.

[0025] At time t1, charging ECU 360 requests power supply ECU 250 to transmit power. As a result, from time t1 to time t2, power is transmitted to capacitor 351 via power receiving relay 340. Accordingly, the voltage detected by voltage sensor 380 gradually increases and becomes higher than the voltage of secondary battery 353. When this voltage reaches a predetermined value, charging ECU 360 determines that charging of capacitor 351 is completed at time t2.

[0026] Thereafter, the charging ECU 360 requests the power transmitting device 10 to stop the power transmission, and controls the charging switch 352 to the ON state while the power transmission is stopped. Then, from time t2 to t3, the electric energy charged in the capacitor 351 is transferred to the secondary battery 353. Then, after a predetermined time has passed and a certain amount of electric energy has been transferred from the capacitor 351 to the secondary battery 353, the charging ECU 360 changes the charging switch 352 from the ON state to the OFF state at time t3. As a result, the charging of the secondary battery 353 is temporarily stopped. At this time, the determination of the stopping of charging may be based on time, or on the difference between the voltage of the capacitor 351 and the voltage of the secondary battery 353 becoming smaller than a threshold value, or on the current flowing from the capacitor 351 to the secondary battery 353 becoming smaller than a threshold value.

[0027] Then, from time t3 to t4, similar to the time t1 to t2, charging of the capacitor 351 is executed. After time t4, electric energy is transferred from the capacitor 351 to the secondary battery 353, similar to the time t2 to t3.

[0028] In this way, during external charging by contactless power transmission and reception, charging of the capacitor 351 from the power transmitting device 10 and transfer of electrical energy from the capacitor 351 to the secondary battery 353 are alternately repeated. Thereafter, when the charge state of the secondary battery 353 reaches a target value or another charging completion condition is satisfied, external charging ends and the power receiving relay 340 is disconnected.

[0029] During external charging by non-contact power transmission and reception, charging switch 352 is repeatedly turned on and off, and therefore the number of times it is turned on and off is significantly greater than that of power receiving relay 340. Therefore, it is preferable to use an element that has a long service life even if it is turned on and off many times, such as a power semiconductor switch that does not have mechanical contacts, rather than an element such as a relay whose service life is determined by the number of times it is turned on and off.

[0030] 4 is a flowchart for explaining the control executed during external charging. When a condition for external charging is met, such as the power receiving device 20 approaching the power transmitting device 10, first, in step S1, the charging ECU 360 sets the charging switch 352 to the OFF state, and then, in step S2, sets the power receiving relay 340 to the ON state. As a result, even if the received power exceeds a value that the secondary battery 353 can accept for some reason during contactless power reception, the secondary battery 353 is not affected.

[0031] Next, in step S3, charging ECU 360 requests power transmission from power supply ECU 250. In response to this, power transmitting device 10 starts transmitting power to power receiving device 20 in step S21, and enters the power transmission state as shown in step S22.

[0032] Here, in step S4, charging ECU 360 periodically determines whether or not charging has been completed to capacitor 351. If charging has not been completed (NO in S4), charging ECU 360 again requests power supply ECU 250 to transmit more power in step S3.

[0033] The determination of whether or not to charge capacitor 351 in step S4 may be made, for example, when a certain period of time has elapsed, or when the difference between the voltage of capacitor 351 and the voltage of secondary battery 353 has exceeded a threshold value.

[0034] When it is determined that charging of capacitor 351 is completed (YES in S4), charging ECU 360 requests power supply ECU 250 to stop power transmission. In response to this, power transmitting device 10 stops power transmission to power receiving device 20 in step S23.

[0035] Next, in step S6, the charging ECU 360 sets the charging switch 352 to the on state. Then, the transfer of electric energy from the capacitor 351 to the secondary battery 353 is performed.

[0036] At this time, in step S7, the charging ECU 360 periodically determines whether or not charging from the capacitor 351 to the secondary battery 353 is complete. If charging is not complete (NO in S7), the charging ECU 360 waits until charging is complete.

[0037] Note that the determination of completion of charging of secondary battery 353 in step S7 may be, for example, when a certain time has elapsed, or when the difference between the voltage of capacitor 351 and the voltage of secondary battery 353 becomes smaller than a threshold value.

[0038] On the other hand, if charging is completed (YES in S7), in step S8, the charging ECU 360 sets the charging switch 352 to the off state. Furthermore, in step S9, the charging ECU 360 determines whether or not to continue receiving power from the power transmitting device 10. If the condition for ending power reception is not met (YES in S9), the charging ECU 360 executes the process from step S2 again. Possible conditions for ending power reception include, for example, when a user instructs the end of power reception, or when the current time reaches the power reception end time set by the schedule management function.

[0039] If charging is not to be continued (NO in S9), charging ECU 360 sets power receiving relay 340 to the OFF state in step S10, and ends the external charging process.

[0040] Fig. 5 is a diagram for explaining a first application example. As shown in Fig. 5, in the case where a plurality of power transmission devices 10 are buried in the road surface along the traveling direction of vehicle 1 indicated by the arrow, when vehicle 1 arrives at the position of power transmission device 10, power is received and capacitor 351 is charged, and when vehicle 1 is located between two power transmission devices 10, electric energy is transferred from capacitor 351 to secondary battery 353. This is also possible by using the control shown in Figs. 3 and 4.

[0041] Fig. 6 is a diagram for explaining the second application example. As shown in Fig. 6, the power transmitting device 10 is buried in the road surface at a place where it is expected that the vehicle will stop due to a traffic light or the like, and the vehicle 1 receives power from the power transmitting device 10 when the vehicle stops due to a red light or a railroad crossing, and stops receiving power and starts moving when the traffic light or the like changes, and transfers electric energy from the capacitor 351 to the secondary battery 353 while traveling. This is also possible by using the control shown in Figs. 3 and 4.

[0042] As described above, according to the vehicle of the present disclosure, when power is received contactlessly, energy is stored in capacitor 351, and when power reception is stopped, the energy is transferred from capacitor 351 to secondary battery 353, thereby preventing deterioration of the secondary battery due to fluctuations in received power when power is received contactlessly.

[0043] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0044] 1 vehicle, 10 power transmission device, 11 power transmission unit, 20 power receiving device, 21 power receiving unit, 100 AC power source, 210 PFC circuit, 220 inverter, 230, 320 filter circuit, 240 power transmission section, 250 power supply ECU, 260, 370 communication section, 270, 380 voltage sensor, 272, 274, 382 current sensor, 310 power receiving section, 330 rectification section, 340 power receiving relay, 350 power storage device, 351 capacitor, 352 charging switch, 353 secondary battery, 360 charging ECU, 390 drive device.

Claims

[Claim 1] a power receiving device capable of contactlessly receiving power from a power transmitting device provided outside the vehicle; a capacitor that stores the power received by the power receiving device; A secondary battery; a driving device that generates a driving force using electric power from the secondary battery; a connection device that connects the capacitor and the secondary battery; a control device for controlling the power receiving device and the connection device, The control device is configured to control the connection device to disconnect the secondary battery and the capacitor when the power receiving device receives power from the power transmitting device, and to control the connection device to connect the secondary battery and the capacitor when the power receiving device stops receiving power.

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