Non-contact power transmission device

Abstract

To provide a contactless power transmission device that can suppress the decrease in transmitted power caused by parasitic inductance resulting from the length of the charging cable. [Solution] The contactless power transmission device of the present invention comprises a power transmission unit that transmits power to the power receiving unit of a contactless power receiving device without contact, an inverter that generates power transmission at a predetermined frequency and supplies it to the power transmission unit, a charging cable that electrically connects the power transmission unit and the inverter, and a control device that controls the inverter to generate power transmission at a specified frequency. The control device acquires information regarding the length of the charging cable and commands the inverter to set a frequency corresponding to the length of the charging cable.

Description

Technical Field

[0001] The present invention relates to a non-contact power transmission device.

Background Art

[0002] Patent Document 1 discloses a power conversion device in which two switching circuits are coupled by a transformer, wherein a transformer is configured by non-contact coupling between a connector having a primary winding and a connector having a secondary winding.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] In a non-contact charging system that transmits power by non-contact coupling between a ground-side connector including a primary coil electrically connected to a charging cable of a non-contact power transmission device installed on the ground, and a vehicle-side connector including a secondary coil of a non-contact power reception device mounted on a vehicle, to charge a high-voltage battery mounted on the vehicle, extension of the charging cable may be required depending on the vehicle specifications. However, extension of the charging cable causes a reduction in transmitted power of a predetermined frequency supplied from an inverter provided in the non-contact power transmission device to the primary coil, due to the influence of parasitic inductance caused by the length of the charging cable. Therefore, there is a risk that the transmission power transmitted from the ground-side connector to the vehicle-side connector, and eventually the charging power for charging the high-voltage battery, may decrease.

[0005] The present invention has been made in view of the above problem, and an object of the present invention is to provide a non-contact power transmission device capable of suppressing a reduction in transmission power caused by the influence of parasitic inductance resulting from the length of a charging cable. [Means for solving the problem]

[0006] To solve the above-mentioned problems and achieve the objective, the non-contact power transmission device according to the present invention comprises: a power transmission unit that transmits power to the power receiving unit of a non-contact power receiving device in a non-contact manner; an inverter that generates power transmission at a predetermined frequency and supplies it to the power transmission unit; a charging cable that electrically connects the power transmission unit and the inverter; and a control device that controls the inverter to generate power transmission at the frequency, wherein the control device acquires information regarding the length of the charging cable and commands the inverter to set the frequency corresponding to the length of the charging cable.

[0007] As a result, the contactless power transmission device according to the present invention can suppress a decrease in power transmission by having the control device command the inverter to set a frequency corresponding to the length of the charging cable based on information regarding the length of the charging cable, thereby reducing the effect of parasitic inductance caused by the length of the charging cable.

[0008] Furthermore, in the above configuration, the control device may command the inverter to use a first frequency when the length of the charging cable is less than a preset threshold, and command the inverter to use a second frequency smaller than the first frequency when the length of the charging cable is equal to or greater than a preset threshold.

[0009] This allows the inverter to be commanded to use a frequency that corresponds to the length of the charging cable, whether it is short or long.

[0010] Furthermore, in the above configuration, the control device may command the inverter to use a third frequency when the length of the charging cable is less than a preset first threshold, to use a fourth frequency smaller than the third frequency when the length of the charging cable is greater than or equal to a preset first threshold but less than a preset second threshold, and to use a fifth frequency smaller than the fourth frequency when the length of the charging cable is greater than or equal to a preset second threshold.

[0011] This allows the control device to command the inverter to use frequencies corresponding to long, medium, and short charging cable lengths, thereby reducing the effects of parasitic inductance caused by the length of the charging cable (such as when the charging cable is extended) and suppressing a decrease in transmitted power.

[0012] Furthermore, in the above configuration, the control device may command the inverter to use a frequency calculated by referring to a preset map showing the relationship between the length of the charging cable and the frequency.

[0013] This allows the control unit to command the inverter to use a frequency calculated by referring to a map based on the length of the charging cable, thereby reducing the effects of parasitic inductance caused by the length of the charging cable (such as when the charging cable is extended) and suppressing a decrease in transmitted power. [Effects of the Invention]

[0014] The contactless power transmission device according to the present invention has the effect of suppressing a decrease in power transmission by reducing the effect of parasitic inductance caused by the length of the charging cable, which is achieved by having the control device command the inverter to set a frequency corresponding to the length of the charging cable based on information about the length of the charging cable. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a diagram showing a schematic configuration of a contactless charging system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of a ground-side non-contact connector and a vehicle-side non-contact connector. [Figure 3] FIG. 3 is a flowchart showing a first example of frequency setting control executed by a ground-side control device of a non-contact power transmission device in the non-contact charging system according to the embodiment. [Figure 4] FIG. 4 is a flowchart showing a second example of frequency setting control executed by a ground-side control device of a non-contact power transmission device in the non-contact charging system according to the embodiment. [Figure 5] FIG. 5 is a flowchart showing a third example of frequency setting control executed by a ground-side control device of a non-contact power transmission device in the non-contact charging system according to the embodiment. MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, an embodiment of a non-contact power transmission device according to the present invention will be described. It should be noted that the present invention is not limited by the present embodiment.

[0017] FIG. 1 is a diagram showing a schematic configuration of a non-contact charging system 1 according to the embodiment.

[0018] As shown in FIG. 1, the non-contact charging system 1 according to the embodiment includes a non-contact power transmission device 2 and a non-contact power reception device 3. In the non-contact charging system 1, the non-contact power transmission device 2 transmits power from an AC power supply 4 to the non-contact power reception device 3 in a non-contact manner via magnetic field coupling.

[0019] The non-contact power transmission device 2 is provided in a parking lot, for example. The non-contact power transmission device 2 is electrically connected to an AC power supply 4 such as a commercial grid power supply, and AC power is supplied from the AC power supply 4 thereto. The non-contact power transmission device 2 includes an AC / DC converter 21, a smoothing capacitor 22, an inverter 23, a ground-side transformer 24, and a ground-side control device 25.

[0020] The AC / DC converter 21 converts AC power supplied from an AC power supply 4 into DC power and outputs the converted DC power to an inverter 23. The smoothing capacitor 22 is provided between the AC / DC converter 21 and the inverter 23, and smoothes the current output from the AC / DC converter 21.

[0021] The inverter 23 is configured by a boost capacitor 231, a switching element 232, and a switching element 233. One end of the boost capacitor 231 is electrically connected to the switching element 232, and the other end is electrically connected to the switching element 233. The switching element 232 and the switching element 233 are electrically connected in series with each other. Furthermore, one end of the switching element 232 is electrically connected to the boost capacitor 231, and the other end is electrically connected to the switching element 233. Further, one end of the switching element 233 is electrically connected to the switching element 232, and the other end is electrically connected to the boost capacitor 231. The inverter 23 converts the DC power input from the AC / DC converter 21 into transmission power having a predetermined frequency (high-frequency power) and outputs the converted power to a ground-side transformer 24. For example, the inverter 23 converts 50 [Hz] or 60 [Hz] AC power (grid power) from the AC power supply 4 into high-frequency power such as 85 [kHz] via the AC / DC converter 21, and outputs the high-frequency power to the ground-side transformer 24.

[0022] The ground-side transformer 24 is a primary coil, and is a power transmission unit that transmits the transmission power having a predetermined frequency supplied from the inverter 23 from the ground-side transformer 24 to a vehicle-side transformer 31 through a magnetic field formed between the ground-side transformer 24 and the vehicle-side transformer 31 serving as a power receiving unit described later. That is, the ground-side transformer 24 and the vehicle-side transformer 31 are magnetically coupled to form a transformer.

[0023] The ground-side control device 25 includes a CPU (Central Processing Unit) and memory. The ground-side control device 25 controls various parts of the contactless power transmission device 2, such as the AC / DC converter 21 and the inverter 23. For example, the ground-side control device 25 controls the switching operation between the on state and the off state of the switching elements 232 and 233 that make up the inverter 23.

[0024] The contactless power receiving device 3 is installed in the vehicle and includes a vehicle-side transformer 31, a rectifier circuit 32, a smoothing capacitor 33, a high-voltage battery 34, and a vehicle-side control device 35.

[0025] The vehicle-side transformer 31 is a secondary coil and a power receiving unit that receives power transmission with a predetermined frequency transmitted from the ground-side transformer 24 of the non-contact power transmission device 2 via a magnetic field formed between it and the ground-side transformer 24 in a non-contact manner. The vehicle-side transformer 31 outputs the received power transmission to the rectifier circuit 32.

[0026] The rectifier circuit 32 converts the power input from the vehicle-side transformer 31 into DC power and outputs it to the high-voltage battery 34. The rectifier circuit 32 is composed of a boost capacitor 321, a switching element 322, and a switching element 323. One end of the boost capacitor 321 is electrically connected to the switching element 322, and the other end is electrically connected to the switching element 323. The switching elements 322 and 323 are electrically connected in series with each other. Furthermore, one end of the switching element 322 is electrically connected to the boost capacitor 321, and the other end is electrically connected to the switching element 323. In addition, one end of the switching element 323 is electrically connected to the switching element 322, and the other end is electrically connected to the boost capacitor 321.

[0027] The smoothing capacitor 33 is placed between the rectifier circuit 32 and the high-voltage battery 34 to smooth the current from the rectifier circuit 32.

[0028] The high-voltage battery 34 has a rechargeable DC power source and is constructed using a secondary battery such as a lithium-ion secondary battery or a nickel-metal hydride battery. The high-voltage battery 34 is charged by power supplied from the rectifier circuit 32. The high-voltage battery 34 supplies power to a motor generator (not shown) and a drive unit (not shown).

[0029] The vehicle-side control device 35 includes a CPU and memory. The vehicle-side control device 35 controls various parts of the contactless power receiving device 3, such as the rectifier circuit 32. The vehicle-side control device 35 controls the switching operation between the on state and the off state of the switching elements 322 and 323 provided in the rectifier circuit 32.

[0030] Figure 2 shows an example of a ground-side contactless connector 201 and a vehicle-side contactless connector 301.

[0031] In the contactless power transmission device 2, the ground-side transformer 24 and the other components of the contactless power transmission device 2 are housed in separate enclosures. Similarly, in the contactless power receiving device 3, the vehicle-side transformer 31 and the other components of the contactless power receiving device 3 are housed in separate enclosures. The ground-side transformer 24 and the vehicle-side transformer 31 are each housed in detachable enclosures, allowing for easy access and isolation. As shown in Figure 2, the ground-side transformer 24 and the vehicle-side transformer 31 constitute the ground-side contactless connector 201 and the vehicle-side contactless connector 301. The vehicle-side contactless connector 301 is built into, for example, a pillar at the rear of the vehicle 300, as shown in Figure 2. The ground-side contactless connector 201, on which the ground-side transformer 24 is located, is electrically connected to the inverter 23 of the contactless power transmission device 2 by a connector cable 202, which is a charging cable. As a result, the power output from the inverter 23 flows through the connector cable 202 and is supplied to the ground-side transformer 24. In addition, the vehicle-side contactless connector 301, on which the vehicle-side transformer 31 is located, is electrically connected to the rectifier circuit 32 of the contactless power transmission device 2 by a power cable routed within the vehicle 300. As a result, the power output from the vehicle-side transformer 31 flows through the power cable and is supplied to the rectifier circuit 32.

[0032] In the contactless power transmission device 2, the longer the length of the connector cable 202 that electrically connects the inverter 23 and the ground-side transformer 24, the larger the inductance value of the parasitic inductance 26 (see Figure 1) of the connector cable 202. In contactless charging, depending on the vehicle model, it may be necessary to extend the connector cable 202 in order to connect (magnetically couple) the ground-side contactless connector 201, which includes the ground-side transformer 24, and the vehicle-side contactless connector 301, which includes the vehicle-side transformer 31, in a contactless manner. However, as the length of the connector cable 202 increases, the inductance value of the parasitic inductance 26 increases, and the electrical characteristics of the connector cable 202 change, resulting in a decrease in the power transmission supplied from the inverter 23 to the ground-side transformer 24. Therefore, the power transmission transmitted from the ground-side transformer 24 to the vehicle-side transformer 31, and consequently the charging power for charging the high-voltage battery 34, decreases.

[0033] In contrast, in the contactless charging system 1 according to the embodiment, the frequency (inverter frequency) of the inverter 23 provided in the contactless power transmission device 2 is changed according to the length of the connector cable 202. As a result, in the contactless charging system 1 according to the embodiment, the effect of parasitic inductance 26 caused by the length of the connector cable 202 is reduced, and the decrease in power transmission supplied from the inverter 23 to the ground-side transformer 24 is suppressed.

[0034] Figure 3 is a flowchart showing a first example of frequency setting control performed by the ground-side control device 25 of the contactless power transmission device 2 in the contactless charging system 1 according to the embodiment.

[0035] First, when the contactless power transmission device 2 is started, the ground-side control device 25 determines whether or not there is a command to set the inverter frequency from the higher-level control device installed in the contactless charging system 1 (step S1). If the ground-side control device 25 determines that there is no command to set the inverter frequency (No in step S1), it returns a series of frequency setting controls. On the other hand, if the ground-side control device 25 determines that there is a command to set the inverter frequency (Yes in step S1), it detects the length of the connector cable 202 (step S2). For example, the contactless power transmission device 2 is equipped with a DIP switch, which is set to Lo if the length of the connector cable 202 is less than a predetermined length, and to Hi if the length of the connector cable 202 is predetermined or longer, at the time of shipment of the contactless power transmission device 2. Then, the ground-side control device 25 detects whether the state of the DIP switch is Lo or Hi, obtains information regarding the length of the connector cable 202, and detects the length of the connector cable 202. Next, the ground-side control device 25 determines whether or not the length of the connector cable 202 is long (step S3). For example, the ground-side control device 25 determines that the connector cable 202 is long if the DIP switch is in the Hi state, and that the connector cable 202 is short if the DIP switch is in the Lo state. If the ground-side control device 25 determines that the connector cable 202 is short (No in step S3), it commands the inverter 23 to set the normal frequency f1 as the inverter frequency (step S4). For example, the frequency f1 is 85 kHz. After that, the ground-side control device 25 returns a series of frequency setting controls. On the other hand, if the ground-side control device 25 determines that the connector cable 202 is long (Yes in step S3), it commands the inverter 23 to set a frequency f2 that is lower than normal as the inverter frequency (step S4). For example, the frequency f2 is 79 kHz. After that, the ground-side control device 25 returns a series of frequency setting controls.

[0036] As a result, in the contactless charging system 1 according to the embodiment, the ground-side control device 25 commands the inverter 23 to set frequencies f1 and f2 according to the case where the length of the connector cable 202 is short and the case where it is long, thereby reducing the effect of parasitic inductance 26 caused by the length of the connector cable 202 and suppressing a decrease in transmitted power. For example, from the results of simulations conducted by the inventors of the present invention, when the length of the connector cable 202 was short and the inverter frequency was 85 [kHz] (frequency f1), the transmitted power was 1.72 [kW]. When the length of the connector cable 202 was long and the inverter frequency was 85 [kHz] (frequency f1), the transmitted power was 1.50 [kW], indicating a decrease in transmitted power. On the other hand, when the length of the connector cable 202 was long and the inverter frequency was 79 [kHz] (frequency f2), the transmitted power became 1.76 [kW], and the decrease in transmitted power was suppressed.

[0037] Figure 4 is a flowchart showing a second example of frequency setting control performed by the ground-side control device 25 of the contactless power transmission device 2 in the contactless charging system 1 according to the embodiment.

[0038] First, when the contactless power transmission device 2 is started, the ground-side control device 25 determines whether or not there is a command to set the inverter frequency from the higher-level control device installed in the contactless charging system 1 (step S11). If the ground-side control device 25 determines that there is no command to set the inverter frequency (No in step S11), it returns a series of frequency setting controls. On the other hand, if the ground-side control device 25 determines that there is a command to set the inverter frequency (Yes in step S11), it detects the length of the connector cable 202 (step S12). For example, the contactless power transmission device 2 is equipped with a DIP switch, which is set to "Lo" if the length of the connector cable 202 is less than the first length, to "Mid" if it is between the first length and the second length, and to "Hi" if it is between the second length and the second length, at the time of shipment of the contactless power transmission device 2. The ground-side control device 25 then detects whether the state of the DIP switch is "Lo", "Mid", or "Hi", obtains information regarding the length of the connector cable 202, and detects the length of the connector cable 202. Next, the ground-side control device 25 determines whether the length of the connector cable 202 is "long," "medium," or "short" (step S13). For example, if the state of the DIP switch is "Hi," the ground-side control device 25 determines that the length of the connector cable 202 is "long." If the state of the DIP switch is "Mid," the ground-side control device 25 determines that the length of the connector cable 202 is "medium." If the state of the DIP switch is "Lo," the ground-side control device 25 determines that the length of the connector cable 202 is "short." If the ground-side control device 25 determines that the length of the connector cable 202 is "long" (long in step S13), it commands the inverter 23 to set frequency f3 as the inverter frequency (step S14). After that, the ground-side control device 25 returns a series of frequency setting controls. Furthermore, if the ground-side control device 25 determines that the length of the connector cable 202 is "medium" (medium in step S13), it commands the inverter 23 to set frequency f4 (> frequency f3) as the inverter frequency (step S15). After that, the ground-side control device 25 returns a series of frequency setting controls.Furthermore, if the ground-side control device 25 determines that the length of the connector cable 202 is "short" (short in step S13), it commands frequency f5 (> frequency f4) as the inverter frequency (step S16). After that, the ground-side control device 25 returns the series of frequency setting controls.

[0039] Based on the above, the ground-side control device 25 commands the inverter 23 to set frequencies f3, f4, and f5 according to the length of the connector cable 202 (long, medium, and short), thereby reducing the effect of parasitic inductance 26 caused by the length of the connector cable 202, such as when the connector cable 202 is extended, and suppressing a decrease in transmitted power.

[0040] Figure 5 is a flowchart showing a third example of frequency setting control performed by the ground-side control device 25 of the contactless power transmission device 2 in the contactless charging system 1 according to the embodiment.

[0041] First, when the contactless power transmission device 2 is started, the ground-side control device 25 determines whether or not there is a command to set the inverter frequency from the higher-level control device installed in the contactless charging system 1 (step S21). If the ground-side control device 25 determines that there is no command to set the inverter frequency (No in step S21), it returns a series of frequency setting controls. On the other hand, if the ground-side control device 25 determines that there is a command to set the inverter frequency (Yes in step S21), it detects the length of the connector cable 202 (step S22). For example, the length of the connector cable 202 is set in multiple ways by corresponding to binary values ​​corresponding to combinations of on and off states of multiple DIP switches installed in the contactless power transmission device 2. Then, the ground-side control device 25 detects the binary values, obtains information regarding the length of the connector cable 202, and detects the length of the connector cable 202. Next, based on the detected length of the connector cable 202, the ground-side control device 25 calculates the frequency f by referring to a map showing the relationship between the length of the connector cable 202 and the frequency f of the inverter frequency (step S23). Next, the ground-side control device 25 commands the inverter 23 to set frequency f as the inverter frequency (step S24). After that, the ground-side control device 25 returns a series of frequency setting controls.

[0042] Based on the above, the ground-side control device 25 commands the inverter 23 to use a frequency f calculated by referring to a map based on the length of the connector cable 202, thereby reducing the effect of parasitic inductance 26 caused by the length of the connector cable 202 due to extensions of the connector cable 202, and suppressing a decrease in power transmission. [Explanation of Symbols]

[0043] 1. Contactless charging system 2. Contactless power transmission device 3. Contactless power receiving device 4 AC power supply 21 AC / DC Converters 22,33 Smoothing Capacitor 23 Inverter 24 Ground-side transformer 25 Ground-side control device 26 Parasitic Inductance 31 Vehicle-side transformer 32 Rectifier circuit 34 High-voltage batteries 35 Vehicle-side control device 201 Ground-side contactless connector 202 Connector Cable 231,321 Boost Capacitors 232,233,322,323 switching elements 300 vehicles 301 Vehicle-side contactless connector

Claims

1. A power receiving unit that transmits power to the power receiving unit without contact, An inverter that generates power transmission power at a predetermined frequency and supplies it to the power transmission unit, A charging cable that electrically connects the power transmission unit and the inverter, A control device that controls the inverter to generate power transmission at the aforementioned frequency, Equipped with, The control device acquires information regarding the length of the charging cable and commands the inverter to set a frequency corresponding to the length of the charging cable. A non-contact power transmission device characterized by the following features.

2. The control device is If the length of the charging cable is less than a preset threshold, the inverter is commanded to set a first frequency. If the length of the charging cable is greater than or equal to a preset threshold, a second frequency smaller than the first frequency is commanded to the inverter. The contactless power transmission device according to feature 1.

3. The control device is If the length of the charging cable is less than a preset first threshold, a third frequency is commanded to the inverter. If the length of the charging cable is greater than or equal to a preset first threshold but less than a second threshold, the inverter is commanded to use a fourth frequency that is smaller than the third frequency. If the length of the charging cable is greater than or equal to a preset second threshold, a fifth frequency smaller than the fourth frequency is commanded to the inverter. The contactless power transmission device according to feature 1.

4. The control device is The frequency calculated by referring to a preset map showing the relationship between the length of the charging cable and the frequency is commanded to the inverter. The contactless power transmission device according to feature 1.

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