Contactless power supply system and lighting system

Abstract

The objective of this disclosure is to enable power supply even when the position of the receiving coil relative to the transmitting coil deviates from a predetermined power-receiving position. [Solution] The contactless power supply system A1 comprises a power transmission device 1 and a power receiving device 2. The power transmission device 1 has a power transmission coil 10 and a power supply circuit unit 11. The power receiving device 2 has a power receiving coil 20, a lighting circuit unit 21, a power receiving side control unit 22, and a position detection unit 23. The lighting circuit unit 21 generates a second power to light up a lighting load 3 from a first power received via the power receiving coil 20 and outputs the second power to the lighting load 3. The power receiving side control unit 22 controls the lighting circuit unit 21 so that the second power increases when the position of the power receiving coil 20 relative to the power transmission coil 10, which is the detection result of the position detection unit 23, is further from the power transmission coil 10 than the power receiving position.

Description

Technical Field

[0001] The present disclosure relates to a non-contact power supply system and a lighting system, and more particularly to a non-contact power supply system in which a power receiving device that is non-contact power-supplied from a power transmission device lights a lighting load, and a lighting system having the non-contact power supply system and the lighting load.

Background Art

[0002] As a conventional example, a lighting device (lighting system) described in Patent Document 1 is exemplified. The lighting device described in Patent Document 1 (hereinafter referred to as the conventional example) includes a power supply unit and a light emitting unit having a light source that is lit by the supply of power from the power supply unit. The power supply unit includes a primary coil (power transmission coil). The light emitting unit includes a secondary coil (power receiving coil) that electromagnetically induces with the primary coil, and is detachably attached to the power supply unit. The conventional example is configured to be able to supply power from the power supply unit to the light emitting unit by electromagnetic induction between the primary coil and the secondary coil.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the conventional example, it is desired that power can be supplied to the light emitting unit (lighting load) even when the position of the secondary coil (power receiving coil) with respect to the primary coil (power transmission coil) deviates from a predetermined power receiving possible position.

[0005] An object of the present disclosure is to provide a non-contact power supply system and a lighting system that can supply power even when the position of the power receiving coil with respect to the power transmission coil deviates from a predetermined power receiving possible position.

Means for Solving the Problems

[0006] A contactless power supply system according to one aspect of the present disclosure comprises a power transmission device that transmits power in a contactless manner via a power transmission coil, and a power receiving device that receives power in a contactless manner via a power receiving coil. The power transmission device includes the power transmission coil and a power supply circuit unit that supplies current to the power transmission coil. The power receiving device includes the power receiving coil, a lighting circuit unit, a power receiving side control unit that controls the lighting circuit unit, and a position detection unit that detects the position of the power receiving coil relative to the power transmission coil. The lighting circuit unit generates a second power to light a lighting load from a first power received via the power receiving coil and outputs the second power to the lighting load. The power receiving side control unit controls the lighting circuit unit to increase the second power when the position detected by the position detection unit is further from the power transmission coil than a predetermined power receiving position.

[0007] A lighting system according to one aspect of this disclosure comprises the contactless power supply system and the lighting load. [Effects of the Invention]

[0008] According to one aspect of this disclosure, a non-contact power supply system and a lighting system have the effect of being able to supply power even if the position of the power receiving coil relative to the power transmitting coil is deviated from a predetermined power-receiving position. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram of a contactless power supply system and a lighting system according to an embodiment of the present disclosure. [Figure 2] Figure 2 is a partially abbreviated block diagram showing a modified example 1 of the same contactless power supply system. [Figure 3] Figure 3 is a partially abbreviated block diagram showing a modified example 2 of the same contactless power supply system. [Figure 4] Figure 4 is a perspective view showing a third modified example of the same lighting system. [Figure 5]Figure 5 is a block diagram showing a modified example 4 of the same non-contact power supply system and lighting system. [Modes for carrying out the invention]

[0010] Hereinafter, a contactless power supply system A1 and a lighting system B1 according to embodiments of this disclosure will be described in detail with reference to the drawings. However, the configurations described in the following embodiments are merely examples of this disclosure. This disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of this disclosure can be achieved.

[0011] (1) Overview The contactless power supply system A1 according to this embodiment comprises a power transmission device 1 that transmits power contactlessly via a power transmission coil 10, and a power receiving device 2 that receives power contactlessly via a power receiving coil 20 (see Figure 1).

[0012] Furthermore, the lighting system B1 according to the embodiment comprises a contactless power supply system A1 according to the embodiment and a lighting load 3 (see Figure 1). The lighting load 3 has, for example, one or more LEDs. The LEDs are preferably, for example, white LEDs for illumination. However, the lighting load 3 may have multiple types of LEDs with different light colors, for example, two LEDs of warm white and daylight color. Alternatively, the lighting load 3 may have three or more LEDs, including red LEDs, green LEDs, and blue LEDs.

[0013] The power transmission device 1 includes a power transmission coil 10 and a power supply circuit 11 that supplies current to the power transmission coil 10. The power supply circuit 11 is configured to supply a high-frequency current of several tens of kHz to several tens of MHz to the power transmission coil 10. The power transmission coil 10 generates a high-frequency magnetic field (magnetic flux) when a high-frequency current flows through it.

[0014] The power receiving device 2 includes a power receiving coil 20, a lighting circuit unit 21, a power receiving side control unit 22 that controls the lighting circuit unit 21, and a position detection unit 23 that detects the position of the power receiving coil 20 relative to the power transmitting coil 10. The lighting circuit unit 21 generates a second power to light the lighting load 3 from the first power received via the power receiving coil 20 and outputs the second power to the lighting load 3. The power receiving coil 20 generates an induced electromotive force by linking with the high-frequency magnetic flux generated by the power transmitting coil 10. In other words, the contactless power supply system A1 according to this embodiment can perform contactless power supply from the power transmitting device 1 to the power receiving device 2 using electromagnetic induction.

[0015] In this case, if the position of the receiving coil 20 of the receiving device 2 relative to the transmitting coil 10 of the transmitting device 1 is deviated from a predetermined power-receiving position, contactless power supply from the transmitting coil 10 to the receiving coil 20 may not occur. As a result, the lighting load 3 connected to the receiving device 2 may not be able to be lit.

[0016] Therefore, in the contactless power supply system A1 according to the embodiment, the power receiving control unit 22 controls the lighting circuit unit 21 to increase the second power when the position of the power receiving coil 20 relative to the power transmitting coil 10, as detected by the position detection unit 23, is further from the power transmitting coil 10 than a predetermined power receiving position. Also, the power receiving control unit 22 controls the lighting circuit unit 21 to decrease the second power when the position of the power receiving coil 20 relative to the power transmitting coil 10, as detected by the position detection unit 23, is closer to the power transmitting coil 10 than the power receiving position.

[0017] As described above, the power receiving control unit 22 controls the lighting circuit unit 21 according to the position of the power receiving coil 20 relative to the power transmitting coil 10, which has the advantage that power can be supplied even if the position of the power receiving coil 20 relative to the power transmitting coil 10 deviates from a predetermined power-receiving position.

[0018] (2) Details (2-1) Configuration of the contactless power supply system according to the embodiment The non-contact power supply system A1 according to the embodiment (hereinafter abbreviated as the non-contact power supply system A1) includes a power transmission device 1 that performs non-contact power transmission via a power transmission coil 10, and a power reception device 2 that performs non-contact power reception via a power reception coil 20 (see FIG. 1).

[0019] The power transmission device 1 has a power transmission coil 10 and a power supply circuit section 11. The power supply circuit section 11 supplies current to the power transmission coil 10. Further, it is preferable that the power transmission device 1 further has a power transmission side control section 12 and a power transmission side communication section 13.

[0020] The power transmission coil 10 may be a cylindrical coil (solenoid) in which a conductor is wound in a tubular shape, or a coil in which a conductor is wound in a spiral shape or the like.

[0021] The power supply circuit section 11 includes a full-wave rectifier that full-wave rectifies an AC voltage and an AC current supplied from an external AC power supply 5, a smoothing capacitor that smooths the pulsating voltage and pulsating current output from the full-wave rectifier, and an inverter circuit that converts the DC voltage and DC current smoothed by the smoothing capacitor into a high-frequency voltage and high-frequency current. The inverter circuit is preferably a half-bridge type inverter circuit having two semiconductor switching elements or a full-bridge type inverter circuit having four semiconductor switching elements. The inverter circuit is configured to convert the DC voltage and DC current smoothed by the smoothing capacitor into a high-frequency voltage and high-frequency current by switching two or four semiconductor switching elements and apply the converted voltage and current to the power transmission coil 10. Note that the frequency of the high-frequency voltage and high-frequency current output from the inverter circuit is preferably on the order of several tens of kHz to several tens of MHz.

[0022] The power transmission side control section 12 mainly includes a microcontroller. The power transmission side control section 12 is configured to control the power supply circuit section 11 by causing a processor of the microcontroller to execute a program. Note that the power transmission side control section 12 may have a drive circuit (drive integrated circuit) that drives two or four semiconductor switching elements included in the inverter circuit of the power supply circuit section 11 separately from the microcontroller.

[0023] The transmitting-side communication unit 13 is configured to transmit and receive wireless signals using electromagnetic waves, including light (visible light or infrared light) and radio waves, as a medium. The transmitting-side communication unit 13 can transmit and receive wireless signals via the transmitting coil 10 by using radio waves with the same frequency as the high-frequency current that the power supply circuit unit 11 flows through the transmitting coil 10 as a medium. Such wireless communication is preferably performed in accordance with a standard called NFC (Near Field Communication).

[0024] The power transmission side communication unit 13 transmits a wireless signal containing data provided by the power transmission side control unit 12. The data provided by the power transmission side control unit 12 is, for example, the dimming level of the lighting load 3. The dimming level is a ratio of the current value when the lighting load 3 is lit at its rated capacity (rated current value) is set to 100%. For example, a dimming level of 50% means a current value that is half of the rated current value. The power transmission side control unit 12 receives a signal transmitted from, for example, a remote controller and provides the power transmission side communication unit 13 with dimming level data according to the command contained in the received signal.

[0025] The power receiving device 2 includes a power receiving coil 20, a lighting circuit unit 21, a power receiving side control unit 22, and a position detection unit 23. Preferably, the power receiving device 2 further includes an abnormality detection unit 24 and a power receiving side communication unit 25.

[0026] The receiving coil 20 may be a solenoid or a coil with a wire wound in a spiral. However, it is preferable that the receiving coil 20 has the same shape as the transmitting coil 10. The receiving coil 20 generates an induced electromotive force by linking with the high-frequency magnetic flux generated by the transmitting coil 10.

[0027] The lighting circuit section 21 includes, for example, a full-wave rectifier with both ends of the receiving coil 20 electrically connected to the AC input terminal, a smoothing capacitor electrically connected to the pulsating output terminal of the full-wave rectifier, and a DC conversion circuit with both ends of the smoothing capacitor electrically connected to the input terminal. The DC conversion circuit is composed of, for example, a buck-boost converter (step-up / step-down chopper). The DC conversion circuit steps up or steps down the DC voltage smoothed by the smoothing capacitor and applies it to the lighting load 3. That is, the lighting circuit section 21 generates a second power to light the lighting load 3 from the first power received via the receiving coil 20 and outputs the second power to the lighting load 3.

[0028] The power receiving control unit 22 primarily consists of a microcontroller. The power receiving control unit 22 is configured to control the lighting circuit unit 21 by having the microcontroller's processor execute a program. In other words, the power receiving control unit 22 controls the lighting circuit unit 21. In addition to the microcontroller, the power receiving control unit 22 may also have a drive circuit (driving integrated circuit) that drives the semiconductor switching elements in the DC conversion circuit of the lighting circuit unit 21.

[0029] The position detection unit 23 detects the position of the receiving coil 20 relative to the transmitting coil 10. As shown in Figure 1, the position detection unit 23 includes a power detection unit 231. The power detection unit 231 has a first current detection circuit that detects the induced current (current) flowing through the receiving coil 20, and a first voltage detection circuit that detects the induced voltage (voltage) applied to the receiving coil 20. Based on the detection results of the first current detection circuit and the detection results of the first voltage detection circuit, the power detection unit 231 detects the first power received via the receiving coil 20.

[0030] Here, the receiving-side control unit 22 determines that the position of the receiving coil 20 relative to the transmitting coil 10 is further from the transmitting coil 10 than a predetermined power-receiving position if the first power detected by the power detection unit 231 is smaller than the reference power. The reference power is the power received via the receiving coil 20 when the receiving coil 20 is located in the power-receiving position. The receiving-side control unit 22 then controls the lighting circuit unit 21 so that the second power increases when the position of the receiving coil 20 relative to the transmitting coil 10 is further from the power-receiving position, as detected by the position detection unit 23. More specifically, the receiving-side control unit 22 controls the lighting circuit unit 21 so that the second power when the position of the receiving coil 20 relative to the transmitting coil 10 is further from the power-receiving position is equal to the second power when the receiving coil 20 is located in the power-receiving position.

[0031] Furthermore, the receiving-side control unit 22 determines that the position of the receiving coil 20 relative to the transmitting coil 10 is closer to the transmitting coil 10 than a predetermined power-receiving position if the first power detected by the power detection unit 231 is greater than the reference power. The receiving-side control unit 22 then controls the lighting circuit unit 21 so that the second power decreases when the position of the receiving coil 20 relative to the transmitting coil 10 is closer to the transmitting coil 10 than the power-receiving position, as detected by the position detection unit 23. More specifically, the receiving-side control unit 22 controls the lighting circuit unit 21 so that the second power when the position of the receiving coil 20 relative to the transmitting coil 10 is closer to the transmitting coil 10 than the power-receiving position is equal to the second power when the receiving coil 20 is located at the power-receiving position.

[0032] As described above, in the contactless power supply system A1 of this embodiment, the position of the receiving coil 20 relative to the transmitting coil 10 is detected based on the magnitude of the first power received by the receiving coil 20, making it possible to detect the above position with a simple configuration.

[0033] The abnormality detection unit 24 includes at least one of a second current detection circuit that detects the induced current flowing through the power receiving coil 20, and a second voltage detection circuit that detects the induced voltage applied to the power receiving coil 20, and a comparator that compares the detected value from the second current detection circuit or the second voltage detection circuit with a threshold value. The second current detection circuit is configured to detect the peak value or average value of the induced current. The second voltage detection circuit is configured to detect the peak value or average value of the induced voltage. Furthermore, the comparator is a wind comparator, and its output becomes low level when the detected value from the second current detection circuit and / or the detected value from the second voltage detection circuit is greater than the upper threshold or less than the lower threshold, and its output becomes high level when the detected value is less than or equal to the upper threshold and greater than or equal to the lower threshold. In other words, the abnormality detection unit 24 detects at least one of the current flowing through the power receiving coil 20 and the voltage applied to the power receiving coil 20, and detects an abnormality in the power receiving device 2 based on at least one of the detected current and voltage.

[0034] Here, the first current detection circuit of the power detection unit 231 and the second current detection circuit of the abnormality detection unit 24 may be the same or different. Similarly, the first voltage detection circuit of the power detection unit 231 and the second voltage detection circuit of the abnormality detection unit 24 may be the same or different.

[0035] The power receiving control unit 22 performs a protective operation to protect at least one of the power transmitting device 1 and the power receiving device 2 when the abnormality detection unit 24 detects an abnormality in the power receiving device 2. Specifically, when the abnormality detection unit 24 detects an abnormality in the power receiving device 2, the power receiving control unit 22 controls the lighting circuit unit 21 as a protective operation so that the second power supplied to the lighting load 3 decreases. More preferably, when the abnormality detection unit 24 detects an abnormality in the power receiving device 2, the power receiving control unit 22 controls (stops) the lighting circuit unit 21 so that the second power supplied to the lighting load 3 becomes zero as a protective operation. With this configuration, safety can be further improved by preventing overcurrent from flowing through the power transmitting device 1 and the power receiving device 2.

[0036] The receiving-side communication unit 25 is configured to receive a wireless signal transmitted from the transmitting-side communication unit 13, acquire data (such as dimming level) contained in the received wireless signal, and pass the acquired data to the receiving-side control unit 22.

[0037] (2-2) Configuration of the lighting system according to the embodiment The lighting system B1 according to the embodiment (hereinafter referred to as lighting system B1) comprises the contactless power supply system A1 described above and a lighting load 3.

[0038] The lighting load 3 preferably has LEDs, but may also have other light-emitting elements, such as organic electroluminescent elements or semiconductor laser elements. The lighting load 3 may be configured integrally with the power receiving device 2, or it may be configured separately and detachably from the power receiving device 2. The lighting load 3 emits light (lights up) when a direct current output from the lighting circuit section 21 of the power receiving device 2 flows through it, and the light intensity is adjusted (dimmed) by increasing or decreasing the value of the direct current. Furthermore, if the lighting load 3 has multiple types of LEDs with different light colors, a direct current is individually supplied to each LED of each light color from the lighting circuit section 21 of the power receiving device 2. The color of the illumination light emitted from the lighting load 3 is then adjusted (color-tuned) by changing the ratio of the current values ​​of the direct currents flowing through each LED of each light color.

[0039] (2-3) Operation of the contactless power supply system and lighting system Next, the operation of the contactless power supply system A1 and the lighting system B1 will be explained. As a prerequisite, the power transmission device 1 is installed in a location where it can be powered by an external power source (AC power supply 5), and the power receiving device 2 is installed in a location where it can receive power from the power transmission device 1 at all times or at any time.

[0040] The power transmission control unit 12 of the power transmission device 1 intermittently operates the power supply circuit unit 11 and intermittently transmits wireless signals from the power transmission communication unit 13. The power transmission control unit 12 continues to operate the power supply circuit unit 11 intermittently unless the power transmission communication unit 13 receives a reply wireless signal including an ACK (acknowledgment) from the power receiving communication unit 25 of the power receiving device 2. If the power transmission control unit 13 receives a reply wireless signal including an ACK from the power receiving communication unit 25 of the power receiving device 2, the power transmission control unit 12 operates the power supply circuit unit 11 continuously and starts supplying power to the power receiving device 2. In other words, the contactless power supply system A1 determines whether the power receiving device 2 is located in a place where it can receive power from the power transmission device 1 by sending and receiving wireless signals between the power transmission device 1 and the power receiving device 2, and operates the power supply circuit unit 11 intermittently if it determines that the power receiving device 2 is not located there. As a result, the contactless power supply system A1 can suppress unnecessary power consumption of the power transmission device 1 while preventing malfunctions (such as temperature rise of foreign matter) that occur when foreign matter (conductors) are present near the power transmission coil 10.

[0041] When the power transmission control unit 12 keeps the power supply circuit unit 11 running continuously, a high-frequency current flows through the power transmission coil 10, generating a magnetic flux. The magnetic flux generated in the power transmission coil 10 links with the power receiving coil 20, inducing an electromotive force in the power receiving coil 20, allowing the power receiving device 2 to receive power. The power receiving device 2 uses the power supplied from the power transmission device 1 to light the lighting load 3 using the lighting circuit unit 21.

[0042] Furthermore, the power transmission control unit 12 receives signals transmitted from the remote controller and provides dimming level data to the power transmission communication unit 13 according to the commands included in the received signals. The power transmission communication unit 13 transmits a wireless signal containing the dimming level data provided by the power transmission control unit 12. If the lighting load 3 has multiple types of LEDs with different light colors, the power transmission control unit 12 causes the power transmission communication unit 13 to transmit color adjustment data, including the dimming level for each LED of each light color, via a wireless signal.

[0043] The receiving-side communication unit 25 receives a wireless signal transmitted from the transmitting-side communication unit 13, acquires the data contained in the wireless signal, and passes it to the receiving-side control unit 22. The receiving-side control unit 22 controls the lighting circuit unit 21 so that the current value of the DC current supplied to the lighting load 3 matches the dimming level of the received data. Specifically, the receiving-side control unit 22 adjusts the DC current output from the lighting circuit unit 21 by PWM control of the DC conversion circuit of the lighting circuit unit 21 to dim the lighting load 3. In addition, the receiving-side control unit 22 adjusts the color of the illumination light emitted from the lighting load 3 by adjusting the DC current output from the lighting circuit unit 21 for each LED of each light color according to the color adjustment data received by the receiving-side communication unit 25.

[0044] As described above, the contactless power supply system A1 transmits a wireless signal including a dimming level from the power-transmitting communication unit 13 to the power-receiving communication unit 25, and causes the power-receiving control unit 22 to control the lighting circuit unit 21 according to the dimming level included in the wireless signal. This allows for dimming of the lighting load 3 while providing contactless power, thereby improving usability.

[0045] Incidentally, the position detection unit 23 of the power receiving device 2 detects the position of the power receiving coil 20 relative to the power transmitting coil 10. More specifically, the position detection unit 23 detects the position of the power receiving coil 20 relative to the power transmitting coil 10 based on the magnitude of the first power, which is the detection result of the power detection unit 231.

[0046] Here, if the position of the receiving coil 20 relative to the transmitting coil 10 is far from a predetermined power-receiving position, the first power received via the receiving coil 20 will be less than the reference power. Therefore, if the first power is less than the reference power, the receiving-side control unit 22 determines that the position of the receiving coil 20 relative to the transmitting coil 10 is far from the power-receiving position. In this case, the second power output from the lighting circuit unit 21 decreases, so the receiving-side control unit 22 controls the lighting circuit unit 21 to increase the second power.

[0047] On the other hand, if the position of the receiving coil 20 relative to the transmitting coil 10 is closer to the transmitting coil 10 than a predetermined power-receiving position, the first power received via the receiving coil 20 will be greater than the reference power. Therefore, if the first power is greater than the reference power, the receiving-side control unit 22 determines that the position of the receiving coil 20 relative to the transmitting coil 10 is closer than the power-receiving position. In this case, the second power output from the lighting circuit unit 21 increases, so the receiving-side control unit 22 controls the lighting circuit unit 21 so that the second power decreases.

[0048] In this way, by controlling the lighting circuit unit 21 according to the detection result of the position detection unit 23, there is an advantage that power can be supplied even if the position of the receiving coil 20 relative to the transmitting coil 10 deviates from a predetermined power-receiving position.

[0049] Furthermore, the abnormality detection unit 24 of the power receiving device 2 detects at least one of the induced current flowing through the power receiving coil 20 and the induced voltage applied to the power receiving coil 20. However, the abnormality detection unit 24 may also detect the current (switching current) flowing through the semiconductor switching elements constituting the DC conversion circuit of the lighting circuit unit 21 instead of the induced current flowing through the power receiving coil 20.

[0050] Here, if any abnormality occurs in the power receiving device 2, for example, the lighting load 3 may short-circuit, causing an excessive current (short-circuit current) to flow through the lighting circuit section 21. Alternatively, if the lighting load 3 is disconnected, current will no longer flow from the lighting circuit section 21 to the lighting load 3. When the current flowing from the power receiving device 2 to the lighting load 3 becomes zero or significantly larger than the rated value, a change occurs in at least one of the induced current flowing through the power receiving coil 20 of the power receiving device 2 and the induced voltage applied to the power receiving coil 20. Specifically, if the power receiving device 2 is normally lighting the lighting load 3, the detected value detected by the second current detection circuit or the second voltage detection circuit of the abnormality detection unit 24 is expected to fall within a range that is below the upper threshold and above the lower threshold. At this time, the abnormality detection unit 24 outputs a high-level detection signal to the power receiving side control unit 22. On the other hand, if a malfunction occurs in the power receiving device 2 and the lighting load 3 cannot be lit, it is assumed that the detection value detected by the second current detection circuit or the second voltage detection circuit of the abnormality detection unit 24 will exceed the upper threshold or fall below the lower threshold. In this case, the abnormality detection unit 24 outputs a low-level detection signal (abnormality detection signal) to the power receiving side control unit 22.

[0051] When the receiving-side control unit 22 receives an abnormality detection signal from the abnormality detection unit 24, it determines that the abnormality detection unit 24 has detected an abnormality and initiates a protective operation to protect at least one of the power receiving device 2 and the power transmitting device 1. After initiating the protective operation, the receiving-side control unit 22 stops the lighting circuit unit 21 so that no induced current flows through the receiving coil 20, or controls the lighting circuit unit 21 to reduce the induced current flowing through the receiving coil 20. In other words, as part of the protective operation, the receiving-side control unit 22 controls the lighting circuit unit 21 so that the second power decreases. Alternatively, as part of the protective operation, the receiving-side control unit 22 controls the lighting circuit unit 21 so that the second power becomes zero. As a result, the contactless power supply system A1 and the lighting system B1 can achieve improved safety compared to when abnormality detection and protective operation are not performed.

[0052] (2-4) Modifications of contactless power supply systems Next, several modifications of the contactless power supply system A1 and the lighting system B1 will be described. However, the basic configuration of each modification described below is the same as the basic configuration of the embodiment. Therefore, components that are common to or substantially common with the basic configuration of the embodiment will be denoted by the same reference numerals, and their illustration and description will be omitted as appropriate. In the following description, "substantially common configuration" means a configuration that differs slightly in shape, size, etc., but has the same function.

[0053] (2-4-1) Variation 1 The contactless power supply system A1 in Modification Example 1 employs a magnetic resonance method (also called magnetic resonance method), which is a type of non-radiative method similar to the electromagnetic induction method, as a contactless power supply method from the power transmission device 1 to the power receiving device 2.

[0054] In Modification 1, the power transmission coil 10, together with the capacitor 141, constitutes a power transmission side resonator 14 (see Figure 2). Also, in Modification 1, the power receiving coil 20, together with the capacitor 261, constitutes a power receiving side resonator 26 (see Figure 2). That is, the power transmission device 1 further has a power transmission side resonator 14 including the power transmission coil 10. Also, the power receiving device 2 further has a power receiving side resonator 26 including the power receiving coil 20.

[0055] However, the non-contact power supply system A1 of Modified Example 1 can supply power from the power transmission device 1 to the power receiving device 2 without contact by causing the power transmission side resonator 14 and the power receiving side resonator 26 to resonate (magnetic field resonance). Furthermore, since the non-contact power supply system A1 of Modified Example 1 performs non-contact power supply from the power transmission device 1 to the power receiving device 2 using the magnetic field resonance method, it is possible to increase the transmission distance (distance between the power transmission coil 10 and the power receiving coil 20) by non-contact power supply compared to the electromagnetic induction method.

[0056] (2-4-2) Modification example 2 The non-contact power supply system A1 of Modified Example 2 is characterized in that the power transmission device 1 is equipped with multiple power transmission coils 10A and 10B. In Modified Example 2, the power transmission device 1 may supply high-frequency current from a single power supply circuit unit 11 to multiple power transmission coils 10A and 10B, or it may be equipped with multiple power supply circuit units 11 that correspond one-to-one with multiple power transmission coils 10A and 10B.

[0057] As shown in Figure 3, the power transmission device 1 in Modified Example 2 has a plurality (for example, two) of power transmission coils 10A and 10B. The power transmission device 1 in Modified Example 2 is configured to supply high-frequency current to each power transmission coil 10A and 10B from a single power supply circuit unit 11. However, the power transmission device 1 in Modified Example 2 may have three or more power transmission coils 10A, 10B, ... Also, the power transmission device 1 in Modified Example 2 may have a plurality of power supply circuit units 11 that correspond one-to-one with the plurality of power transmission coils 10A and 10B, and may be configured to supply high-frequency current individually to each power transmission coil 10A, 10B, ... from the plurality of power supply circuit units 11.

[0058] However, the non-contact power supply system A1 of the modified example 2 can supply power to two power receiving devices 2 simultaneously from one power transmitting device 1, thereby improving usability. Furthermore, the non-contact power supply system A1 of the modified example 2 can improve usability by increasing the flexibility of the installation location of the power receiving devices 2 by installing multiple power transmitting coils 10A and 10B in different locations.

[0059] (2-4-3) Modification 3 The lighting system B1 of Modification 3 comprises a contactless power supply system A1 and a lighting fixture 6 (see Figure 4). The power transmission device 1 of the contactless power supply system A1 in Modification 3 is installed on the underside of the tabletop 40 of the table 4. However, the multiple (for example, four) power transmission coils 10A, 10B, 10C, and 10D of the power transmission device 1 in Modification 3 are arranged vertically and horizontally with spacing between them on the surface (top) of the tabletop 40 of the table 4.

[0060] The lighting fixture 6 comprises a base 60 that houses the power receiving device 2 and the power receiving coil 20 and is placed on the upper surface of the deck 40, a cylindrical main body 61 that protrudes upward from the base 60, and a lamp body 62 that is rotatably connected to the tip (upper end) of the main body 61. In other words, the lighting fixture 6 is a so-called LED desk lamp. The power receiving coil 20 is provided on the lower surface of the base 60. The lighting load 3 is provided on the lamp body 62.

[0061] In Modification 3, the power transmission device 1 supplies power to the power receiving device 2 via one of the multiple power transmission coils 10A, 10B, 10C, and 10D, which overlaps with the base 60 of the lighting fixture 6. In other words, the lighting system B1 of Modification 3 can be used by placing the lighting fixture 6 at any location on the upper surface of the deck 40 (where the multiple power transmission coils 10A, 10B, 10C, and 10D are located), so there is no need to provide a power cord to the lighting fixture 6, and the installation location can be freely selected, improving usability.

[0062] (2-4-4) Modification 4 In the non-contact power supply system A1 of the modified example 4, the position detection unit 23 of the power receiving device 2 includes a distance detection unit 232 that detects the distance between the power transmitting coil 10 and the power receiving coil 20, instead of the power detection unit 231 (see Figure 5).

[0063] The distance detection unit 232 is, for example, a distance sensor that utilizes infrared light. The distance sensor includes a light-emitting unit that emits infrared light and a light-receiving unit that receives infrared light. The light-emitting unit and light-receiving unit included in the distance sensor are arranged near the power receiving coil 20 of the power receiving device 2 and detect the distance to the power transmitting coil 10 of the power transmitting device 1. Specifically, the distance sensor can detect the distance from the power receiving coil 20 to the power transmitting coil 10 (the distance between the power receiving coil 20 and the power transmitting coil 10) by having the light-receiving unit receive the reflected light that has been reflected back from the power transmitting coil 10 out of the infrared light emitted from the light-emitting unit.

[0064] The distance detection unit 232 is not limited to a distance sensor that uses infrared light; for example, it may be a distance sensor that uses ultrasound or a laser.

[0065] The receiving-side control unit 22 determines that the position of the receiving coil 20 relative to the transmitting coil 10 is further from the transmitting coil 10 than the power-receiving position if the distance detected by the distance detection unit 232 is longer than the reference distance. The reference distance is the distance between the transmitting coil 10 and the power-receiving position. Then, because the position of the receiving coil 20 relative to the transmitting coil 10 is further from the transmitting coil 10 than the power-receiving position, the receiving-side control unit 22 controls the lighting circuit unit 21 so that the second power supplied from the lighting circuit unit 21 to the lighting load 3 increases.

[0066] Furthermore, the receiving-side control unit 22 determines that the position of the receiving coil 20 relative to the transmitting coil 10 is closer to the transmitting coil 10 than the power-receiving position if the distance detected by the distance detection unit 232 is shorter than the reference distance. Then, the receiving-side control unit 22 controls the lighting circuit unit 21 so that the second power supplied from the lighting circuit unit 21 to the lighting load 3 decreases, since the position of the receiving coil 20 relative to the transmitting coil 10 is closer to the transmitting coil 10 than the power-receiving position.

[0067] As described above, in the non-contact power supply system A1 of the modified example 4, the position of the receiving coil 20 relative to the transmitting coil 10 is detected based on the distance between the transmitting coil 10 and the receiving coil 20, making it possible to detect the above position with a simple configuration.

[0068] (3) Summary A non-contact power supply system (A1) according to a first aspect of this disclosure comprises a power transmission device (1) that transmits power non-contact via a power transmission coil (10) and a power receiving device (2) that receives power non-contact via a power receiving coil (20). The power transmission device (1) includes a power transmission coil (10) and a power supply circuit unit (11) that supplies current to the power transmission coil (10). The power receiving device (2) includes a power receiving coil (20), a lighting circuit unit (21), a power receiving side control unit (22) that controls the lighting circuit unit (21), and a position detection unit (23) that detects the position of the power receiving coil (20) relative to the power transmission coil (10). The lighting circuit unit (21) generates a second power to light a lighting load (3) from a first power received via the power receiving coil (20) and outputs the second power to the lighting load (3). The power receiving control unit (22) controls the lighting circuit unit (21) to increase the second power if the position detected by the position detection unit (23) is further from the power transmission coil (10) than a predetermined power receiving position.

[0069] In the first embodiment of the non-contact power supply system (A1), the lighting circuit unit (21) is controlled to increase the second power when the position detected by the position detection unit (23) is further from the power transmission coil (10) than a predetermined power-receiving position. This has the advantage that power can be supplied even if the position of the power receiving coil (20) relative to the power transmission coil (10) deviates from a predetermined power-receiving position.

[0070] A contactless power supply system (A1) according to a second aspect of this disclosure can be realized in combination with the first aspect. In the contactless power supply system (A1) according to the second aspect, the power receiving control unit (22) controls the lighting circuit unit (21) to reduce the second power when the position detected by the position detection unit (23) is closer to the power transmission coil (10) than the power receiving position.

[0071] In the second embodiment of the non-contact power supply system (A1), the lighting circuit unit (21) is controlled to reduce the second power when the position detected by the position detection unit (23) is closer to the power transmission coil (10) than a predetermined power-receiving position. This has the advantage that power can be supplied even if the position of the power-receiving coil (20) relative to the power transmission coil (10) is deviated from a predetermined power-receiving position.

[0072] A contactless power supply system (A1) according to a third aspect of this disclosure can be realized in combination with the second aspect. In the contactless power supply system (A1) according to the third aspect, the position detection unit (23) includes a power detection unit (231) that detects a first power. The receiving-side control unit (22) determines that the position is further from the transmitting coil (10) than the power-receiving position if the first power detected by the power detection unit (231) is less than the reference power. The receiving-side control unit (22) determines that the position is closer to the transmitting coil (10) than the power-receiving position if the first power detected by the power detection unit (231) is greater than the reference power.

[0073] In the third aspect of the contactless power supply system (A1), the position of the receiving coil (20) relative to the transmitting coil (10) is detected based on the magnitude of the first power received by the receiving coil (20), making it possible to detect the above position with a simple configuration.

[0074] A contactless power supply system (A1) according to a fourth aspect of this disclosure can be realized in combination with the second aspect. In the contactless power supply system (A1) according to the fourth aspect, the position detection unit (23) includes a distance detection unit (232) that detects the distance between a power transmission coil (10) and a power receiving coil (20). The power receiving side control unit (22) determines that the position is further from the power transmission coil (10) than the power receiving position if the distance detected by the distance detection unit (232) is longer than a reference distance. The power receiving side control unit (22) determines that the position is closer to the power transmission coil (10) than the power receiving position if the distance detected by the distance detection unit (232) is shorter than a reference distance.

[0075] In the non-contact power supply system (A1) according to the fourth embodiment, the position of the receiving coil (20) relative to the transmitting coil (10) is detected based on the distance between the transmitting coil (10) and the receiving coil (20), making it possible to detect the above position with a simple configuration.

[0076] A contactless power supply system (A1) according to a fifth aspect of this disclosure can be realized in combination with any of the first to fourth aspects. In the contactless power supply system (A1) according to the fifth aspect, the power receiving device (2) further includes an abnormality detection unit (24). The abnormality detection unit (24) detects at least one of the current flowing through the power receiving coil (20) and the voltage applied to the power receiving coil (20), and detects an abnormality based on at least one of the detected current and voltage. The power receiving side control unit (22) performs a protective operation to protect at least one of the power transmitting device (1) and the power receiving device (2) when the abnormality detection unit (24) detects an abnormality.

[0077] In the contactless power supply system (A1) according to the fifth embodiment, the abnormality detection unit (24) causes the power receiving side control unit (22) to perform a protective operation when it detects an abnormality, thereby improving safety compared to the case where no abnormality is detected and no protective operation is performed.

[0078] A contactless power supply system (A1) according to a sixth aspect of this disclosure can be realized in combination with a fifth aspect. In the contactless power supply system (A1) according to the sixth aspect, it is preferable that the power receiving control unit (22) controls the lighting circuit unit (21) so that the second power is reduced as a protective operation.

[0079] The contactless power supply system (A1) according to the sixth embodiment can further improve safety by controlling the lighting circuit section (21) so as to reduce the second power, thereby preventing overcurrent from flowing to the power transmission device (1) and the power receiving device (2).

[0080] A contactless power supply system (A1) according to a seventh aspect of this disclosure can be realized in combination with a sixth aspect. In the contactless power supply system (A1) according to the seventh aspect, it is preferable that the power receiving control unit (22) controls the lighting circuit unit (21) so that the second power becomes zero as a protective operation.

[0081] The contactless power supply system (A1) according to the seventh embodiment can further improve safety by controlling the lighting circuit section (21) so that the second power becomes zero, thereby preventing overcurrent from flowing to the power transmission device (1) and the power receiving device (2).

[0082] A non-contact power supply system (A1) according to the eighth aspect of this disclosure can be realized in combination with any of the first to seventh aspects. In the non-contact power supply system (A1) according to the eighth aspect, the power transmission device (1) preferably further comprises a power transmission side resonator (14) including a power transmission coil (10). The power receiving device (2) preferably further comprises a power receiving side resonator (26) including a power receiving coil (20).

[0083] The non-contact power supply system (A1) according to the eighth embodiment performs non-contact power supply from the power transmission device (1) to the power receiving device (2) using a magnetic field resonance method, and therefore, compared to the electromagnetic induction method, it is possible to extend the transmission distance by non-contact power supply.

[0084] A lighting system (B1) according to the ninth aspect of this disclosure comprises a contactless power supply system (A1) according to any of the first to eighth aspects, and a lighting load (3).

[0085] The lighting system (B1) according to the ninth embodiment has the advantage that it can supply power even if the position of the receiving coil (20) relative to the transmitting coil (10) is deviated from a predetermined power-receiving position. [Explanation of symbols]

[0086] A1 Contactless power supply system B1 Lighting System 1. Power transmission equipment 2. Power receiving device 3. Lighting load 10 Power transmission coil 11 Power supply circuit section 14. Transmission side resonator 20 Power receiving coil 21 Lighting circuit section 22 Power receiving side control unit 23 Position detection unit 24 Anomaly detection unit 26. Receiving side resonator 231 Power detection unit 232 Distance detection unit

Claims

1. A power transmission device that transmits power without contact via a power transmission coil, A power receiving device that receives power non-contact via a power receiving coil, The aforementioned power transmission device is The aforementioned power transmission coil, It has a power supply circuit section that supplies current to the power transmission coil, The power receiving device is The aforementioned power receiving coil, A lighting circuit unit that generates a second power to light a lighting load from a first power received via the power receiving coil and outputs the second power to the lighting load, A power receiving side control unit that controls the aforementioned lighting circuit section, It includes a position detection unit that detects the position of the receiving coil relative to the transmitting coil, The power receiving control unit controls the lighting circuit unit to increase the second power when the position detected by the position detection unit is further from the power transmission coil than a predetermined power receiving position. Contactless power supply system.

2. The power receiving control unit controls the lighting circuit unit so that the second power is reduced when the position detected by the position detection unit is closer to the power transmission coil than the power receiving position. The contactless power supply system according to claim 1.

3. The position detection unit includes a power detection unit that detects the first power, The power receiving side control unit is: If the first power detected by the power detection unit is smaller than the reference power, it is determined that the position is further from the power transmission coil than the power receiving position. If the first power detected by the power detection unit is greater than the reference power, it is determined that the position is closer to the power transmission coil than the power-receiving position. The contactless power supply system according to claim 2.

4. The position detection unit includes a distance detection unit that detects the distance between the power transmission coil and the power receiving coil. The power receiving side control unit is: If the distance detected by the distance detection unit is longer than the reference distance, it is determined that the position is further from the power transmission coil than the power receiving position. If the distance detected by the distance detection unit is shorter than the reference distance, it is determined that the position is closer to the power transmission coil than the power-receiving position. The contactless power supply system according to claim 2.

5. The power receiving device is The system further includes an abnormality detection unit that detects at least one of the current flowing through the receiving coil and the voltage generated in the receiving coil, and detects an abnormality based on at least one of the detected current and voltage. The power receiving control unit performs a protective operation to protect at least one of the power transmitting device and the power receiving device when the abnormality detection unit detects the abnormality. A contactless power supply system according to any one of claims 1 to 4.

6. The power receiving control unit controls the lighting circuit section so that the second power is reduced as a protective operation. The contactless power supply system according to claim 5.

7. The power receiving control unit controls the lighting circuit section so that the second power becomes zero as a protective operation. The contactless power supply system according to claim 6.

8. The power transmission device further includes a power transmission side resonator which includes the power transmission coil, The power receiving device further comprises a power receiving side resonator including the power receiving coil. A contactless power supply system according to any one of claims 1 to 4.

9. A contactless power supply system according to any one of claims 1 to 4, The aforementioned lighting load and, Lighting system.

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