Power reception device for non-contact power supply system

Abstract

A power reception device for a non-contact power supply system includes a processor configured to: acquire information of a power transmission device; and change a criterion of a fail-safe assessment at a time of power supply from the power transmission device to a power reception device based on the acquired information of the power transmission device.

Description

POWER RECEPTION DEVICE FOR NON-CONTACT POWER SUPPLY SYSTEM

[0001] The present disclosure relates to a power reception device for a non-contact power supply system.

[0002] Patent Literature 1 discloses a technique in which, if compatibility between a road-side power transmission device and a vehicle-side power reception device is satisfied, and there is a possibility that a power storage device is overcharged, charge control is performed by short range wireless communication, and if there is no possibility that the power storage device is overcharged, the charge control by the short-range wireless communication is not performed.

[0003] JP 2024-109473 A

[0004] In non-contact power supply, it is desirable to perform switching of fail-safe assessment according to compatibility with the power transmission device or rated output of the power transmission device in addition to switching of the charge control according to the compatibility as disclosed in Patent Literature 1. Therefore, there is room for improvement in the technique disclosed in Patent Literature 1.

[0005] The present disclosure has been made in view of the above, and an object of the present disclosure is to provide a power reception device for a non-contact power supply system capable of switching a criterion of a fail-safe assessment according to a configuration on a power transmission device side.

[0006] A power reception device for a non-contact power supply system includes a processor configured to: acquire information of a power transmission device; and change a criterion of a fail-safe assessment at a time of power supply from the power transmission device to a power reception device based on the acquired information of the power transmission device.

[0007] According to the present disclosure, it is possible to switch the criterion of the fail-safe assessment according to the configuration on the power transmission device side.

[0008] FIG. 1 is a diagram illustrating a schematic configuration of a non-contact power supply system according to an embodiment.FIG. 2 is a flowchart illustrating a first example of a power supply control method by a power reception device for a non-contact power supply system according to the embodiment.FIG. 3 is a flowchart illustrating a second example of the power supply control method by the power reception device for the non-contact power supply system according to the embodiment.

[0009] A power reception device for a non-contact power supply system and the non-contact power supply system according to the embodiment of the present disclosure will be described with reference to the drawings. Note that components in the following embodiment include components that those skilled in the art can easily replace or components that are substantially the same.

[0010] (Non-contact power supply system) A configuration of the non-contact power supply system according to the embodiment will be described with reference to FIG. 1. The non-contact power supply system according to the embodiment is a wireless power transfer system that supplies power to a traveling or stopping vehicle in a contactless manner by using, for example, magnetic resonance coupling (magnetic field resonance). A vehicle to which power is to be supplied is an electric vehicle that can be charged with power supplied from an external power supply, and is, for example, a battery electric vehicle (BEV), a plug-in hybrid electric vehicle (PHEV), or the like.

[0011] A non-contact power supply system 1 includes a power transmission device 11 and a power reception device 12. The power transmission device 11 includes a power transmission ECU 111, a communication device 112, a power transmission coil 113, a resonant circuit 114, a filter circuit 115, an inverter 116, and a power supply 117. Note that the power transmission device 11 may include a power factor collection (PFC) circuit including an AC / DC converter between the inverter 116 and the power supply 117.

[0012] The power transmission ECU 111 is an electronic control unit that controls the power transmission device 11. The power transmission ECU 111 includes a processor and a memory. The processor includes a central processing unit (CPU), a digital signal processor (DSP), a field-programmable gate array (FPGA), and the like. Note that the processor may include a control device (a device not using a semiconductor) other than a semiconductor device. The memory is a main storage device, and includes a random access memory (RAM), a read only memory (ROM), and the like. The power transmission ECU 111 loads a program stored in a predetermined storage unit into a work area of the memory (main storage device) and executes the program, and controls each component and the like through the execution of the program, thereby implementing a function that matches a predetermined purpose.

[0013] The power transmission ECU 111 can adjust (limit) power to be transmitted to the power reception device 12 (power for power transmission) by, for example, controlling a switching element included in the inverter 116. Furthermore, the power transmission ECU 111 may adjust the power to be transmitted to the power reception device 12, by controlling a duty cycle and drive frequency of the inverter 116 and voltage of the power supply 117.

[0014] The communication device 112 communicates with a communication device 122 of the power reception device 12 with short-range wireless communication or wide-area wireless communication. The communication device 112 communicates with the communication device 122 to acquire a power requirement (amount of power required) of the vehicle, vehicle identification information (vehicle ID), and the like.

[0015] The short-range wireless communication is, for example, communication with a communication distance of less than 10 meters, and is communication with a short communication distance as compared with the wide-area wireless communication. As the short-range wireless communication, for example, communication conforming to any communication standard formulated by IEEE, ISO, IEC, or the like can be used. Furthermore, as the short-range wireless communication, for example, Wi-Fi (registered trademark), Bluetooth (registered trademark), ZigBee (registered trademark), or the like can be used. Furthermore, as a technique for performing short-range wireless communication, radio frequency identification (RFID), dedicated short range communication (DSRC), or the like may be used.

[0016] The wide-area wireless communication is, for example, communication with a communication distance of 10 meters to 10 kilometers, and is communication with a long communication distance as compared with the short-range wireless communication. As the wide-area wireless communication, for example, communication conforming to communication standards such as 3GPP (registered trademark), 4G, LTE, 5G, and WiMAX formulated by IEEE can be used.

[0017] The power transmission coil (primary coil) 113 is embedded in a lane on a road, for example. A plurality of the power transmission coils 113 may be arranged along the lane on the road. In the power transmission device 11, when AC power is supplied from the filter circuit 115 to the resonant circuit 114, current flows through the power transmission coil 113, and a magnetic field for power transmission is generated.

[0018] The resonant circuit 114 includes, for example, a plurality of resonant capacitors. The resonant capacitor is connected in series to, for example, one end and another end of the power transmission coil 113. Furthermore, a resonance frequency of the resonant circuit 114 is 10 kHz to 100 GHz, preferably 85 kHz. Furthermore, the resonance frequency of the resonant circuit 114 is configured to coincide with the drive frequency of the inverter 116.

[0019] The filter circuit 115 reduces noise included in AC current input from the inverter 116, and outputs, to the resonant circuit 114, the AC power from which the noise has been reduced. The filter circuit 115 is, for example, an LC filter in which inductors (variable inductors) and capacitors (variable capacitors) are combined.

[0020] The inverter 116 converts DC power input from the power supply 117 into AC power and outputs the AC power to the filter circuit 115. The inverter 116 includes, for example, a switching element such as an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field effect transistor, (MOSFET) or the like. Furthermore, the drive frequency of the inverter 116 is, for example, 85 kHz.

[0021] The power supply 117 includes, for example, a commercial power supply.

[0022] The power reception device 12 is provided, for example, at a bottom of a vehicle body of the vehicle. Furthermore, the power reception device 12 includes a vehicle ECU 121, the communication device 122, a power reception coil 123, a resonant circuit 124, a filter circuit 125, a rectifier 126, and a battery 127.

[0023] The vehicle ECU 121 is an electronic control unit that controls the vehicle. The vehicle ECU 121 has a hardware configuration similar to a hardware configuration of the power transmission ECU 111. The vehicle ECU 121 can adjust (limit) power (power for charging) supplied to the battery 127 by controlling a switching element included in the rectifier 126.

[0024] The vehicle ECU 121 can switch the power reception coil 123 between a power receiving state and a non-power receiving state by, for example, short-circuiting or opening a circuit that constitutes the rectifier 126 and changing impedance of the power reception coil 123. Furthermore, the vehicle ECU 121 may switch the power reception coil 123 between the power receiving state and the non-power receiving state by changing a resonance frequency on, for example, a variable inductor and variable capacitor included in the power reception device 12.

[0025] Here, depending on a combination of systems on a power transmission device 11 side (ground side) and a power reception device 12 side (vehicle side), coils or circuit configurations may be mismatched, and a failure may occur at a time of power supply. Therefore, in the power reception device for the non-contact power supply system according to the present embodiment, the criterion of the fail-safe assessment is switched according to a configuration on the power transmission device 11 side.

[0026] Note that "fail-safe" represents processing of switching the power reception coil 123 to the non-power receiving state, stopping a power supply request, or the like for circuit protection, in a case where, for example, power transmitted from the power transmission device 11 is greater than power required by the power reception device 12. Furthermore, the "criterion of the fail-safe assessment" represents a threshold for determining necessity of the fail-safe processing described above.

[0027] Specifically, the vehicle ECU 121 acquires information of the power transmission device 11. Examples of the information of the power transmission device 11 include the following. (1) A rated output of the power transmission device 11 (2) Length of the power transmission coil 113 (length in a direction along a driving lane) (3) Shape of the power transmission coil 113 (4) The number of the power transmission coil 113

[0028] The vehicle ECU 121 acquires information of the power transmission device 11 with wide-area communication, short-range communication, or the like using the communication device 122, for example. Furthermore, the vehicle ECU 121 may acquire the information of the power transmission device 11 by utilizing, for example, a weak power transmission phase (a phase of checking whether the power reception device 12 is a voltage source or a current source by causing a short-circuit state) in a tracking mode in the non-contact power supply.

[0029] Subsequently, based on the acquired information of the power transmission device 11, the vehicle ECU 121 changes the criterion of the fail-safe assessment at a time of power supply from the power transmission device 11 to the power reception device 12. It is conceivable that there is a plurality of methods for changing a criterion of the fail-safe assessment performed by the vehicle ECU 121.

[0030] For example, the vehicle ECU 121 may change a threshold of voltage, current, or element temperature in the fail-safe assessment based on the acquired information of the power transmission device 11. The threshold of voltage is a threshold for determining overvoltage at a time of power reception from the power transmission device 11. Furthermore, the threshold of current is a threshold for determining overcurrent at the time of power reception from the power transmission device 11. Furthermore, the threshold of element temperature is a threshold related to an upper limit temperature of elements (for example, the switching elements of the rectifier 126, or the like) that constitute the power reception device 12, at a time of power reception from the power transmission device 11.

[0031] For example, an input current to the battery 127 differs 10 times between a case where a rated power of the power transmission device 11 is 3 kW and a case where the rated power is 30 kW. Therefore, even in a case where the power reception device 12 can withstand up to 30 kW, it is desirable to lower the threshold at a time of determining as overcurrent by 1 / 10 for determination. Similar applies to the voltage and the element temperature.

[0032] For example, in a case where the rated power of the power transmission device 11 is great, the voltage and current at a time of power supply are also great, and heat generated by the elements that constitute the power reception device 12 increases. Therefore, in the power reception device 12, it is desirable to determine as soon as possible whether or not the voltage is overvoltage, whether the current is overcurrent, and whether the temperature has reached the upper limit temperature of the elements. Therefore, in a case where the rated power of the power transmission device 11 is greater than a predetermined criterion, the vehicle ECU 121 decreases the threshold of voltage, current, or element temperature in the fail-safe assessment as compared with a case where the rated power is smaller than the predetermined criterion.

[0033] Meanwhile, for example, in a case where the rated power of the power transmission device 11 is small, the voltage and current at a time of power supply are also small, and heat generated by the elements that constitute the power reception device 12 decreases. Therefore, in the power reception device 12, it is not necessary to determine so early whether or not the voltage is overvoltage, whether the current is overcurrent, and whether the temperature has reached the upper limit temperature of the elements. Therefore, in a case where the rated power of the power transmission device 11 is smaller than the predetermined criterion, the vehicle ECU 121 increases the threshold of voltage, current, or element temperature in the fail-safe assessment as compared with a case where the rated power is greater than the predetermined criterion.

[0034] Subsequently, at the time of power supply from the power transmission device 11 to the power reception device 12, the vehicle ECU 121 performs fail-safe assessment based on the threshold changed as described above. Then, upon judging a fail based on threshold, the vehicle ECU 121 executes fail-safe such as switching the power reception coil 123 to the non-power receiving state, for example.

[0035] Furthermore, the vehicle ECU 121 may calculate a threshold at a time of an estimated power supply time in the fail-safe assessment (also simply referred to as an "estimated power supply time") based on the acquired information of the power transmission device 11. The threshold of the estimated power supply time represents a time during which the power transmission coil 113 and the power reception coil 123 face each other in a vertical direction at the time of power supply from the power transmission device 11 to the power reception device 12. Specifically, it is conceivable that there are two types of thresholds, an upper threshold and a lower threshold, as the threshold of the estimated power supply time. For example, in a case where a coil length of the power transmission coil 113 is short (in a case of a short coil), the vehicle ECU 121 calculates the upper threshold. Furthermore, for example, in a case where the coil length of the power transmission coil 113 is long (in a case of a long coil), the vehicle ECU 121 calculates the lower threshold.

[0036] The threshold of the estimated power supply time can be calculated from, for example, speed of the vehicle 4 (vehicle speed) and the length of the power transmission coil 113 (coil length). For example, in a case where the coil length of the power transmission coil 113 is short (in the case of a short coil), the time during which the power transmission coil 113 and the power reception coil 123 face each other is short, and the power supply also ends immediately, and therefore the estimated power supply time is short. Meanwhile, in a case where the coil length of the power transmission coil 113 is long (in the case of a long coil), the time during which the power transmission coil 113 and the power reception coil 123 face each other is long, and the power supply also does not end immediately, and therefore the estimated power supply time is long.

[0037] Therefore, the vehicle ECU 121 calculates the threshold (the upper threshold or the lower threshold) of the estimated time of power supply from the power transmission device 11 to the power reception device 12, based on the vehicle speed and the coil length of the power transmission coil 113. Note that, for example, upon acquiring the information about the length of the power transmission coil 113, the vehicle ECU 121 may judge, based on the predetermined reference length, whether the power transmission coil 113 is a short coil or a long coil. Then, based on the vehicle speed, the vehicle ECU 121 may calculate the upper threshold in a case of the short coil and the lower threshold in a case of the long coil.

[0038] Subsequently, the vehicle ECU 121 counts time of the power supply from the power transmission device 11 to the power reception device 12. Subsequently, in a case where the power transmission coil 113 is a short coil, when the counted power supply time exceeds the upper threshold of the estimated power supply time, the vehicle ECU 121 determines a fail. The "power supply time exceeds the upper threshold of the estimated power supply time" represents a situation in which, for example, even though the power transmission coil 113 is a short coil, the time of the power supply to the power reception device 12 is longer than assumed (the power supply is not interrupted).

[0039] Furthermore, in a case where the power transmission coil 113 is a long coil, when the counted power supply time falls below the lower threshold of the estimated power supply time, the vehicle ECU 121 determines a fail. The "power supply time falls below the lower threshold of the estimated power supply time" represents a situation in which, for example, even though the power transmission coil 113 is a long coil, the time of the power supply to the power reception device 12 is shorter than assumed (the power supply is interrupted).

[0040] Upon judging a fail as described above, the vehicle ECU 121 executes the fail-safe such as switching the power reception coil 123 to the non-power receiving state, for example. Hereinafter, the rest of the configurations of the power reception device 12 will be described.

[0041] The communication device 122 communicates with the communication device 112 of the power transmission device 11 with the short-range wireless communication or the wide-area wireless communication. The communication device 122 communicates with the communication device 112 to transmit the power requirement (amount of power required) of the vehicle, the vehicle identification information (vehicle ID), and the like.

[0042] The power reception coil (secondary coil) 123 receives the power transferred from the power transmission coil 113 in a contactless manner. That is, in the non-contact power supply system 1, for example, when the vehicle travels on the road on which the power transmission coil 113 is installed, the power transmission coil 113 on a ground side and the power reception coil 123 on a vehicle side face each other in a vertical direction, by which power is transferred in a contactless manner.

[0043] The resonant circuit 124 includes, for example, a plurality of resonant capacitors. The resonant capacitor is connected in series to, for example, one end and another end of the power reception coil 123. The resonance frequency of the resonant circuit 124 is determined to coincide with the resonance frequency of the resonant circuit 114.

[0044] The filter circuit 125 reduces noise included in AC current input from the resonant circuit 124, and outputs, to the rectifier 126, the AC power from which the noise has been reduced. The filter circuit 125 is, for example, an LC filter in which inductors (variable inductors) and capacitors (variable capacitors) are combined.

[0045] The rectifier 126 converts the AC power input from the filter circuit 125 into DC power and outputs the DC power to the battery 127. The rectifier 126 includes, for example, a full-bridge circuit in which four diodes are full-bridge connected as rectifier elements. Furthermore, a switching element is connected in parallel to each diode of the rectifier 126. Each of these switching elements includes for example, an IGBT, and performs switching operation in accordance with a control signal from the vehicle ECU 121.

[0046] The battery 127 is a DC power supply that can be charged, and includes, for example, a lithium ion battery, a nickel-metal hydride battery, or the like. The battery 127 stores the power supplied from the power transmission device 11 to the power reception device 12. Furthermore, the battery 127 is electrically connected to a traction motor via a power control unit (PCU), and can supply power to the traction motor.

[0047] (Power supply control method 1) A first example of a power supply control method by the power reception device for the non-contact power supply system according to the embodiment will be described with reference to FIG. 2. Hereinafter, an example will be described in which a threshold of the fail-safe assessment in the power reception device 12 is changed according to the configuration on the power transmission device 11 side

[0048] First, the vehicle ECU 121 acquires information of the power transmission device 11 with wide-area communication, short-range communication, or the like using the communication device 122, for example (step S1). Subsequently, the vehicle ECU 121 changes the threshold of the fail-safe assessment (the threshold of voltage, current, or element temperature) based on the acquired information (for example, the rated output) of the power transmission device 11 (step S2).

[0049] Subsequently, based on the changed threshold, the vehicle ECU 121 determines whether or not a fail has occurred during the power supply (step S3). In a case where it is determined in step S3 that a fail has occurred during the power supply (Yes in step S3), the vehicle ECU 121 executes the fail-safe such as, for example, switching the power reception coil 123 to the non-power receiving state (step S4), and completes the present processing. Meanwhile, in a case where it is determined in step S3 that no fail has occurred during the power supply (No in step S3), the vehicle ECU 121 completes the present processing.

[0050] (Power supply control method 2) A second example of the power supply control method by the power reception device for the non-contact power supply system according to the embodiment will be described with reference to FIG. 3. Hereinafter, an example will be described in which a threshold of the estimated power supply time of the fail-safe assessment in the power reception device 12 is calculated according to the configuration on the power transmission device 11 side.

[0051] First, the vehicle ECU 121 acquires information of the power transmission device 11 with wide-area communication, short-range communication, or the like using the communication device 122, for example (step S11). Subsequently, the vehicle ECU 121 calculates the threshold of the estimated power supply time based on the acquired information of the power transmission device 11 (for example, a coil length) and the vehicle speed (step S12). In step S12, the vehicle ECU 121 calculates the upper threshold in a case where the power transmission coil 113 is a short coil, and the vehicle ECU 121 calculates the lower threshold in a case where the power transmission coil 113 is a long coil.

[0052] Subsequently, the vehicle ECU 121 determines whether or not power is being supplied from the power transmission device 11 to the power reception device 12 (step S13). In step S13, based on, for example, a change in electrical characteristic during the power supply or the like, the vehicle ECU 121 determines whether or not power is being supplied.

[0053] In a case where it is determined in step S13 that power is being supplied (Yes in step S13), the vehicle ECU 121 counts up the power supply time (step S14). Meanwhile, in a case where it is determined in step S13 that power is not being supplied (No in step S13), the vehicle ECU 121 performs a counter reset (step S15).

[0054] Subsequently, the vehicle ECU 121 determines whether a power supply time counter exceeds the upper threshold or whether the power supply time counter is below the lower threshold (step S16). In a case where it is determined in step S16 that the power supply time counter exceeds the upper threshold or is below the lower threshold (Yes in step S16), the vehicle ECU 121 determines that a fail has occurred during the power supply (step S17). Subsequently, the vehicle ECU 121 executes the fail-safe such as switching the power reception coil 123 to the non-power receiving state, for example (step S18), and completes the present processing. Note that, in a case where it is determined in step S16 that the power supply time counter is equal to or smaller than the upper threshold or equal to or greater than the lower threshold (No in step S16), the vehicle ECU 121 completes the present processing.

[0055] With the power reception device for the non-contact power supply system according to the above-described embodiment, the criterion of the fail-safe assessment can be switched according to the configuration on the power transmission device 11 side to supply power. Furthermore, with the power reception device for the non-contact power supply system according to the embodiment, fail-safe corresponding to the power transmission device 11 can be applied, and thus it is possible to construct a non-contact power supply system capable of supporting different types of power transmission devices 11.

[0056] Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the disclosure in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0057] 1 Non-contact power supply system 11 Power transmission device 111 Power transmission ECU 112 Communication device 113 Power transmission coil 114 Resonant circuit 115 Filter circuit 116 Inverter 117 Power supply 12 Power reception device 121 Vehicle ECU 122 Communication device 123 Power reception coil 124 Resonant circuit 125 Filter circuit 126 Rectifier 127 Battery

Claims

1. A power reception device for a non-contact power supply system, comprising 　　　a processor configured to: 　　　　　　acquire information of a power transmission device; and 　　　　　　change a criterion of a fail-safe assessment at a time of power supply from the power transmission device to a power reception device based on the acquired information of the power transmission device.

2. The power reception device according to claim 1, wherein the processor is configured to: 　　　change a threshold of voltage, current, or element temperature in fail-safe assessment based on the acquired information of the power transmission device; and 　　　perform the fail-safe assessment based on the changed threshold.

3. The power reception device according to claim 1, wherein the processor is configured to: 　　　calculate a threshold of estimated time of the power supply from the power transmission device to the power reception device based on the acquired information of the power transmission device; and 　　　perform the fail-safe assessment based on the calculated threshold.

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