TW201315081A - Non-contact electric power supply device - Google Patents

Abstract

An FET (2H) is always off and an FET (2L) is always on in a presence detection. The FETs (1H, 1L) are alternately switched on and off. When in half-bridge operation, power consumption is lower than when in full-bridge operation. Accordingly, magnetic energy of a power supply coil (L1) in the half-bridge operation is lower than magnetic energy of the power supply coil (L1) in the full-bridge operation. Hence, even when power supply coils (L1) which are located in close proximity to one another have respectively carried out power supply and presence detection, interference by magnetic energy from the power supply coil (L1) in line with presence detection with magnetic energy from the power supply coil (L1) in line with power supply is suppressed.

Description

Contactless power supply

The present invention relates to a contactless power supply device that supplies power to a power receiving device in a non-contact manner.

In the past, there has been a non-contact power supply system that supplies power from a power supply device to a power receiving device in a non-contact manner (see, for example, Patent Document 1).

In recent years, in order to further improve user convenience, a so-called free-layout type non-contact power supply system has been proposed, and the power receiving device is installed at any position on the top surface (power supply surface) of the power supply device, and power can be supplied to the power receiving device. Inside the power supply unit of this system, a plurality of primary coils are arranged along the power supply surface. The power supply device excites the primary coil in the region where the power receiving device exists. The secondary coil of the power receiving device is induced to generate electricity by a change in the magnetic flux from the primary coil of the excitation (see, for example, Patent Document 2).

The power receiving device is not required to be located at a specific position as long as it is disposed in the power supply surface of the power supply device. For example, it is expected that this non-contact power supply system can be used for charging a mobile terminal in which a power receiving device is built.

Moreover, the power supply device performs presence detection using the primary coil to detect whether there is an object such as a power receiving device on the power supply surface. The presence detection system intermittently excites the primary coil and performs the change according to the current flowing through the coil at this time. For example, when an object exists in the vicinity of the primary coil, the primary coil is in a state of being magnetically coupled to the object, so that the impedance of the primary coil is increased. Therefore, the current flowing through the primary coil is reduced. Therefore, when the current of the energized primary coil is below the threshold, the power supply device detects the presence of an object around the primary coil.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2003-204637

Patent Document 2: Japanese Laid-Open Patent Publication No. 2008-5573

The power supply device performs presence detection every fixed period by the one-time coil other than the primary coil of the power supply even when power is supplied to the power receiving device. Therefore, in some cases, the adjacent two primary coils are simultaneously powered and detected. In this case, the two magnetic fields formed by the two primary coils may interfere with each other. Therefore, it is possible to reduce the magnetic energy acting on the secondary coil and reduce the power supply efficiency to the phase receiving device.

It is an object of the present invention to provide a non-contact power supply device capable of suppressing a decrease in power supply efficiency when power is supplied to a power receiving device at the same time and detection is detected.

In order to solve the above problems, the contactless power supply device of the present invention includes a power supply surface for setting the power receiving device and a plurality of power supply units disposed along the power supply surface, and at least one power supply unit among the plurality of power supply units Generating a magnetic flux and supplying the power receiving device to the power receiving device in a non-contact manner by electromagnetic induction of the magnetic flux, wherein the plurality of power supply units each include: a first power source side switching element and a first ground side switching element; The power supply and the ground are connected in series; the second power supply side switching element and the second ground side switching element are connected in series between the power supply and the ground; and the power supply coil is operatively connected to the first power supply side switching element and a first connection point between the first ground-side switching elements and a second connection point between the second power-side switching element and the second ground-side switching element; and an excitation drive circuit for each of the switching elements Turning off, causing the power supply coil to be excited to generate magnetic flux; and detecting means for detecting presence or absence of an object disposed on the power supply surface according to the current or voltage of the power supply coil; Exciting driving circuit when the power supply by the power receiving device, the set of first power supply side switching elements and said second ground-side of the switching element, and a second power source side switching The first switching element and the first grounding side switching element are electrically connected to each other, and the excitation driving circuit detects the presence or absence of an object by the presence detecting unit, and the first power supply side switching element and the first ground side are The switching element is alternately turned off, and the second power supply side switching element is fixed in a disconnected state, and the second ground side switching element is fixed in an on state.

Further, in the above configuration, when the presence detecting unit detects the presence or absence of an object, the first ground is turned on when the first power supply side switching element and the first ground side switching element are alternately turned on and off. The on-time of the side switching element is set such that the on-time of the first ground-side switching element is longer than the off-time.

Further, in the above configuration, the excitation drive circuit is configured to cut the first and second power supply side switching elements in a standby state in which neither detection nor power supply is performed.

Further, in the above configuration, the excitation drive circuit turns on only one of the first and second ground-side switching elements in the standby state, and connects the first power supply side switching element and the second power supply. The side switching element is turned off.

Further, in the above configuration, the presence detecting unit detects whether the object provided on the power feeding surface is metal based on the current or voltage of the power feeding coil.

According to the present invention, it is possible to suppress a decrease in power supply efficiency when power is supplied to the power receiving device and detection is performed in the non-contact power supply device.

(Best form of implementing the invention)

Hereinafter, an embodiment in which the non-contact power supply device of the present invention is embodied in a non-contact power supply system will be described with reference to Figs. 1 to 8 .

As shown in FIG. 1, the contactless power supply system includes a power supply device 10 and a power receiving device 30. In this example, the power receiving device 30 is built in the mobile terminal device 40. The specific configuration of the power supply device 10 and the power receiving device 30 will be described below.

(power supply device)

As shown in FIG. 2, the power supply device 10 is covered by a flat casing 5. A power supply surface 6 for arranging the mobile terminal 40 is formed on the top surface of the casing 5.

The power supply device 10 is internally provided with 24 sets of coil groups, which are spread over the entire area of the power supply surface 6. The coil group includes a power supply coil L1 and a primary side foreign object detecting coil L2. The coil group is arranged in a matrix of 4 rows × 6 columns, for example, on the power feeding surface 6.

As shown in FIG. 1, the power supply device 10 includes a single common unit 11 and a plurality of power supply units 15 (24 in this example) connected to the common unit 11.

The common unit 11 includes a power supply circuit 13, a common control circuit 12, and a non-volatile memory 14.

The memory 14 stores a pre-registered ID number unique to the power receiving device 30.

The power supply circuit 13 converts the alternating current from the external power source into an appropriate direct current voltage, and supplies the direct current voltage to each of the power supply units 15 and the common unit 11 as operating power.

The common control circuit 12 is constituted by a microcomputer. The common control circuit 12 integrally controls the power supply device 10 by giving various command signals to the respective power supply units 15.

The power supply unit 15 includes a unit control circuit 19, an excitation drive circuit 16, a foreign matter detecting circuit 21, signal extracting circuits 17, 22, and a memory 24. The excitation drive circuit 16 is connected to the power supply coil L1, and the foreign matter detecting circuit 21 is connected to the primary foreign object detecting coil L2.

The common control circuit 12 outputs a command signal indicating that power is required to be output to each unit control circuit 19. The unit control circuit 19 outputs a command signal indicating that the full-bridge operation is required to the excitation drive circuit 16 in accordance with the above-described command signal from the common control circuit 12.

As shown in FIG. 3, the excitation drive circuit 16 includes four FETs (Field Effect Transistors) 1H, 2H, 1L, and 2L, and two gate drivers 16a and 16b that control the gates of the respective FETs.

Specifically, between the power source Vdd and the ground, two connection lines A1 and A2 are connected in parallel. The two connecting lines A1 and A2 are located at opposite positions in the left-right direction in the drawing, and are connected via a connecting line A3 extending in the left-right direction. Hereinafter, among the two connection lines A1 and A2, the upper side of the connection line A3 is referred to as the Hi side, and the lower side of the connection line A3 is referred to as the Lo side. The source terminal and the NMOS terminal of the FET 1H are connected to the Hi side of the connection line A1, and the source terminal and the NMOS terminal of the FET 1L are connected to the Lo side of the connection line A1. The source side and the 汲 terminal of the FET 2H are connected to the Hi side of the connection line A2, and are connected. The source terminal and the NMOS terminal of the FET 2L are connected to the Lo side of the line A2. The power supply coil L1 and the capacitor C are connected in series to the connection line A3.

The first gate driver 16a is connected to the gate terminals of the two FETs 1H and 1L. Further, the second gate driver 16b is connected to the gate terminals of the two FETs 2H and 2L. The two gate drivers 16a and 16b output signals of Hi level or Lo level to the gate terminals of the FETs 1H, 2H, 1L, and 2L. When the FETs 1H, 2H, 1L, and 2L receive the signal of the Hi level, they are turned on, and the source terminal and the gate terminal are turned on. Further, when the FETs 1H, 2H, 1L, and 2L receive the signal of the Lo level, they are turned off, and the source terminal and the gate terminal are blocked. In addition, when no signal is received, each FET is turned off.

The two gate drivers 16a, 16b perform a full bridge operation in accordance with a command signal from the unit control circuit 19 that requires full bridge operation. In the full-bridge operation, the two gate drivers 16a and 16b switch the on-off states of the FETs 1H, 2H, 1L, and 2L, and the combination of the two FETs 1H and 2L and the combination of the two FETs 1L and 2H are synchronized. As shown in FIG. 4, while the Hi level signal is output to the two FETs 1H and 2L, the Lo level signal is output to the other two FETs 1L and 2H. On the other hand, while the Hi level signal is output to the other two FETs 1L and 2H, the two FETs 1H and 2L are output to the Lo level signal. In the full-bridge operation, a failure time t1 at which the signal of the Lo level is output to all of the FETs 1H, 2H, 1L, and 2L is set.

As shown in FIG. 3, when the two FETs 1H and 2L located on the diagonal line are in an on state, the other two FETs 1L and 2H are turned off. At this time, the current from the power supply Vdd flows to the ground via the FET 1H, the power supply coil L1, the capacitor C, and the FET 2L. Further, while the other two FETs 1L and 2H are in an on state, the two FETs 1H and 2L are turned off. In this state, the current from the power supply Vdd flows to the ground via the FET 2H, the capacitor C, the power supply coil L1, and the FET 1L. In this manner, by switching the on-off state of each of the FETs 1H, 2H, 1L, and 2L, the high-frequency current is supplied to the power supply coil L1. Therefore, the power supply coil L1 is excited, and the magnetic flux from the power supply coil L1 changes. The power supply efficiency of this full bridge operation is higher than the power supply efficiency of the half bridge operation described later. Therefore, the full bridge action is suitable for power supply.

Moreover, in the failure time t1, all of the FETs 1H, 2H, 1L, and 2L are cut. Broken state. Therefore, when the on-off state of the two FETs 1H and 2L is switched to the on-off state of the other two FETs 1L and 2H, the switching timing is shifted, thereby suppressing, for example, a through current from the power supply Vdd via the two FETs 1H and FET1L. And flow to ground.

Further, the two FETs 1H and 2H correspond to the power source side switching elements, and the two FETs 1L and 2L correspond to the ground side switching elements.

As shown in FIG. 3, a signal extraction circuit 17 is provided between the power supply coil L1 and the capacitor C. The signal extracting circuit 17 includes a current detecting circuit 27, an envelope detecting circuit 25, and a waveform shaping circuit 26.

The current detecting circuit 27 is connected between the power feeding coil L1 and the capacitor C. The current detecting circuit 27 detects the current flowing between the power supply coil L1 and the capacitor C, and outputs the detection result to the envelope detecting circuit 25. The envelope detecting circuit 25 performs envelope detection on the waveform of the signal from the current detecting circuit 27, and outputs the detected signal to the waveform shaping circuit 26. The waveform shaping circuit 26 is constituted by a filter, an amplifier, and the like. The waveform shaping circuit 26 shapes the waveform of the signal by removing noise in the detection signal and performing signal amplification, and outputs the shaped signal to the unit control circuit 19.

Next, it is explained that the presence detection of the presence of an object is detected on the power supply surface 6.

The common control circuit 12 transmits, in order for the power supply unit 15 of the non-power supply, an instruction signal requesting execution of the presence detection. When the unit control circuit 19 receives the command signal, it outputs a command signal indicating that the half bridge operation is required to the excitation drive circuit 16. When the excitation drive circuit 16 (the two gate drivers 16a and 16b) receives this command signal, the high-frequency current is supplied to the power supply coil L1 via the half bridge operation.

Specifically, as shown in FIG. 5, in the half bridge operation, the second gate driver 16b often outputs a signal of the Lo level to the FET 2H, and outputs a signal of the current Hi level to the FET 2L. Further, the first gate driver 16a outputs a signal of the Lo level to the FET 1L while outputting the signal of the Hi level to the FET 1H, and outputs a signal of the Lo level to the signal of the Hi level when the signal of the Hi level is output to the FET 1L. FET1H. The first gate driver 16a also outputs a signal of the Hi level and the Lo level in the same period T1 as the full bridge operation in the half bridge operation. Among them, in the half bridge type operation, the duty ratio of the signal output to the FET 1L is set to a value exceeding 50%. So, FET1L The time to be in the on state is longer than the time in which the FET 1H is turned on. In the half bridge operation, a failure time t1 at which the signal of the Lo level is output to all of the FETs 1H, 2H, 1L, and 2L is also set.

As shown in FIG. 6, when there is detection, the FET 2H is always turned off, and the FET 2L is always turned on. Further, the on-off states of the two FETs 1H and 1L are alternately switched. When the FET 1H is turned on and the FET 1L is turned off, the current from the power supply Vdd flows to the ground via the FET 1H, the power supply coil L1, the capacitor C, and the FET 2L. Thereafter, the FET 1H is switched to the off state, and when the FET 1L is switched to the on state, the power supply coil L1 generates a counter electromotive force. The accompanying current flows to the ground via the capacitor C, the power supply coil L1, and the FET 1L. In this manner, by switching the on-off state of the two FETs 1H and 1L, the high-frequency current is supplied to the power supply coil L1. In the half bridge operation, the time during which the power from the power supply Vdd is supplied to the power supply coil L1 is limited to a period in which the FET 1H is turned on. Therefore, in the half bridge operation, by increasing the duty ratio of the signal (Hi level) output to the FET 1L, the time for supplying power from the power supply Vdd to the power supply coil L1 can be shortened. Therefore, the power consumption in the half bridge operation can be made lower than the above-described full bridge operation.

Further, the magnetic energy generated by the power supply coil L1 in the half bridge operation is also smaller than the above-described full bridge type operation. Therefore, even when the two power supply coils L1 that are close to each other are supplied with power and detected, the magnetic energy from the power supply coil L1 is detected along with the magnetic energy from the power supply coil L1 accompanying the power supply. Interference will also be suppressed. As a result, the power supply efficiency from the power supply coil L1 to the power receiving device 30 due to the power supply is suppressed from being reduced by the presence detection.

Further, in the failure time t1, the two FETs 1H and 1L are turned off. Therefore, when the ON/OFF states of the two FETs 1H and 1L are switched, the switching timing is shifted, and for example, the through current flows from the power supply Vdd to the ground via the FET 1H and the FET 1L.

The unit control circuit 19 supplies a high-frequency current to the power supply coil L1 by the half bridge operation, and detects whether or not an object exists around the power supply coil L1 based on the detection result of the signal extraction circuit 17 at this time. For example, when an object exists in the vicinity of the power supply coil L1, the power supply coil L1 is magnetically coupled to the object, and the impedance of the power supply coil L1 is increased. Therefore, the current flowing through the power supply coil L1 is reduced. When the unit control circuit 19 determines that the current of the power supply coil L1 is less than the threshold value in accordance with the voltage level (the detection level) from the signal extraction circuit 17, it is determined that an object exists around the power supply coil L1. Further, when the unit control circuit 19 determines that the current of the power supply coil L1 is equal to or higher than the threshold value based on the voltage level from the signal extraction circuit 17, it is determined that there is no object in the vicinity of the power supply coil L1. The unit control circuit 19 outputs the presence detection result to the common control circuit 12. The common control circuit 12 excites only the power supply coil L1 in the region where the power receiving device 30 (correctly, the power receiving coil L3) exists, via the presence detection.

Further, the unit control circuit 19, the signal extracting circuit 17, and the power feeding coil L1 correspond to the presence detecting unit.

Further, the unit control circuit 19 authenticates whether or not the power receiving device 30 is a regular product based on the detection result of the signal extraction circuit 17 at the time of power supply (when the full-bridge operation is performed). Here, the amplitude of the high-frequency signal supplied to the power supply coil L1 is modulated by the power receiving device 30 to be described later, and is changed between two values for each predetermined period. This amplitude is varied in accordance with the ID information in response to the load modulation caused by the power receiving device 30.

The unit control circuit 19 recognizes the ID information based on the voltage level from the signal extraction circuit 17, and compares the ID information with the ID information previously memorized by the memory 24. The unit control circuit 19 outputs the success or failure of the ID comparison to the common control circuit 12.

The common control circuit 12 continues to supply power when it is determined that the ID comparison is established. On the other hand, the common control circuit 12 determines that the power receiving device 30 is not normal and stops supplying power when the ID comparison is not established.

Next, the detection of foreign matter in the presence of foreign matter such as metal between the power supply surface 6 and the power receiving device 30 will be described.

As shown in FIG. 1, the unit control circuit 19 controls the operation of the foreign object detecting circuit 21 in accordance with a command signal from the common control circuit 12 that requires foreign matter detection. Specifically, the foreign matter detecting circuit 21 supplies a high-frequency current to the primary foreign object detecting coil L2 in the same manner as the excitation driving circuit 16 . Therefore, the primary foreign object detecting coil L2 is excited. Further, the power supply coil L1 and the primary foreign object detecting coil L2 are excited at different frequencies.

The amplitude of the high-frequency current of the primary foreign object detecting coil L2 is modulated by the power receiving device 30, and is changed between two values for each predetermined period. For example, when there is a foreign matter such as metal between the primary foreign object detecting coil L2 and the power receiving device 30 (the secondary foreign object detecting coil L4), the period in which the amplitude changes between the two values is lengthened. The signal extracting circuit 22 is configured in the same manner as the signal extracting circuit 17 described above. Therefore, the signal extracting circuit 22 generates a detection signal composed of the Hi level or the Lo level in response to the amplitude changed between the two values. The unit control circuit 19 determines the presence or absence of foreign matter based on the period of the detection signal from the signal extraction circuit 22. The unit control circuit 19 outputs a judgment result regarding the presence or absence of foreign matter to the common control circuit 12. The common control circuit 12 does not perform power supply when it is judged that there is a foreign matter, and performs power supply when it is judged that no foreign matter exists.

When the unit control circuit 19 is not powered and there is detection, the excitation drive circuit 16 is in a standby state. Specifically, as shown in FIG. 7, each of the gate drivers 16a and 16b outputs a signal of Hi level only to the FET 2L, and outputs a signal of the Lo level to the other three FETs 1H, 2H, and 1L. Therefore, only the FET 2L is turned on, and the other three FETs 1H, 2H, and 1L are turned off. This is the standby state. In the standby state, the power supply coil L1 and the power supply Vdd are electrically blocked. Therefore, for example, when a circuit having a low impedance on the power supply Vdd side exists, the current induced by the specific power supply coil L1 flows into the circuit direction in accordance with the magnetic energy from the power supply coil L1 located around the specific power supply coil L1. Further, by turning off the FET 1L, the regenerative current is generated via the FET 2L, the power supply coil L1, and the FET 1L. In this manner, only the FET 2L is turned on in the standby state, and magnetic coupling with the power supply coil L1 located in the periphery can be suppressed. Moreover, when the power supply coil L1 located in the periphery is supplied with power, magnetic coupling is received, and the power supply efficiency of the power supply coil L1 can be suppressed from being lowered. Further, when the power supply coil L1 located at the periphery of the power supply detects presence, it is suppressed that the accuracy of detection is lowered.

(power receiving device)

As shown in FIG. 1, the power receiving device 30 includes a rectifier circuit 31, a power receiving coil L3, a secondary side control circuit 33, and a DC/DC converter 35.

The power receiving coil L3 is inductively changed by the magnetic flux change from the power supply coil L1. Streaming electricity. The rectifier circuit 31 rectifies the AC power induced by the power receiving coil L3. The DC/DC converter 35 converts the DC voltage from the rectifier circuit 31 into a value suitable for the operation of the mobile terminal 40. This DC voltage is used, for example, for charging a secondary battery (not shown), which is an operating power source of the mobile terminal unit 40.

The secondary side control circuit 33 is constituted by a microcomputer. The secondary side control circuit 33 receives a part of the electric power from the rectifying circuit 31 and operates by the electric power.

Further, the power receiving device 30 includes a secondary side foreign matter detecting coil L4, a rectifying circuit 36, a oscillating device 37, a load 38, and a transistor 39, and performs load modulation for foreign matter detection.

The secondary side foreign matter detecting coil L4 is connected to the rectifier circuit 36. Further, a damper 37 is connected to the rear stage of the rectifier circuit 36. Further, a load 38 is connected between the secondary side foreign object detecting coil L4 and the ground. A transistor 39 is provided between the load 38 and ground. In detail, the emitter terminal of the transistor 39 is connected to the ground. A collector 38 is connected to the collector terminal of the transistor 39. The base terminal of the transistor 39 is connected to the damper 37.

The secondary side foreign object detecting coil L4 receives a high frequency signal from the primary side foreign object detecting coil L2 by electromagnetic induction, and outputs the received high frequency signal to the rectifier circuit 36. The rectifier circuit 36 rectifies the high frequency signal and outputs the rectified signal to the oscillating device 37. The damper 37 generates a pulse wave composed of a Hi level and a Lo level repeat based on the high frequency signal, and outputs the pulse wave to the base terminal of the transistor 39. The transistor 39 switches the conduction cut-off state in accordance with the Hi level and the Lo level in the pulse wave. When the transistor 39 is in the on state, a part of the current of the secondary side foreign object detecting coil L4 flows to the ground. Therefore, the amplitude of the high-frequency signal of the secondary side foreign object detecting coil L4 changes between two values for each fixed period in accordance with the on-off state of the transistor 39. Along with this, the amplitude of the high-frequency signal of the primary foreign object detecting coil L2 also changes between two values (load modulation) every fixed period.

When foreign matter exists between the primary foreign object detecting coil L2 and the secondary foreign object detecting coil L4, the amplitude of the high frequency signal transmitted and received between the two foreign object detecting coils L2 and L4 becomes small. Therefore, the repetition period of the Hi level and the Lo level of the pulse wave generated by the damper 37 becomes long, and the switching period of the ON/OFF state of the transistor 39 becomes long. Therefore, the amplitude of the high-frequency signal transmitted and received between the two foreign object detecting coils L2 and L4 is between two values. The period of change becomes longer. Therefore, as described above, foreign matter detection can be performed on the power supply device 10.

Further, the power receiving device 30 includes a load modulation circuit 42 and an authentication signal generating circuit 41, and performs load modulation for authentication. This authentication signal generating circuit 41 is provided in the secondary side control circuit 33.

The authentication signal generating circuit 41 generates a pulse wave composed of a combination of a Hi level and a Lo level. The combination of the Hi level and the Lo level displays the ID information inherent to the power receiving device 30.

The load modulation circuit 42 is constituted by a load, a transistor, or the like. The load modulation circuit 42 changes the amplitude (load modulation) of the high-frequency signal of the power receiving coil L3 and the power feeding coil L1 in accordance with the Hi level and the Lo level of the pulse wave from the authentication signal generating circuit 41. Thereby, as described above, the ID comparison can be performed in the power supply device 10.

Next, the processing sequence of the common control circuit 12 will be described with reference to the flowchart of FIG. The flow chart is executed when the US is in a fixed cycle. Further, at the beginning of the flowchart, the power supply surface 6 is not provided, and the excitation drive circuit 16 is placed in a standby state.

First, the common control circuit 12 causes the majority of the excitation drive circuits 16 of the plurality of power supply units 15 to perform presence detection in accordance with the sequential half-bridge operation (S101). When the common control circuit 12 determines that the presence of an object is not detected (NO in S102), the processing is terminated after the excitation drive circuit 16 is returned to the standby state (S103). When the common control circuit 12 determines that the detected object is present (YES in S102), foreign matter detection such as metal is performed (S104). When the common control circuit 12 determines that the foreign matter is detected (YES in S105), the excitation drive circuit 16 returns to the standby state (S103), and the processing ends. Thereby, it is possible to suppress the foreign matter from being excited.

When the common control circuit 12 determines that no foreign matter is detected (NO in S105), the excitation drive circuit 16 operates in a full-bridge manner to reduce the power supply (S106). Further, the common control circuit 12 determines whether or not the ID comparison is established (S107). When the common control circuit 12 determines that the ID comparison is not established (NO in S107), the power supply is stopped via the excitation drive circuit 16 (S108), and the excitation drive circuit 16 is returned to the standby state (S103), and the processing is terminated. Thereby, it is possible to effectively prevent power supply to the outside of the regular power receiving device 30.

When the common control circuit 12 determines that the ID comparison is established (YES in S107), the power supply is continuously supplied (S109). And, after the fixed control circuit 12 has passed the fixed time in the power supply, It is judged again whether or not the ID comparison is established (S107). That is, the ID comparison is also performed periodically in the power supply.

As described above, according to the embodiment described above, the following effects can be exhibited.

(1) When there is detection, the FET 2H is always turned off, and the FET 2L is always turned on. Further, the two FETs 1H and 1L are turned on and off (half-bridge operation). In the half bridge operation, the supply time of the electric power from the power source Vdd to the power supply coil L1 is limited to the period in which the FET 1H is turned on. Therefore, the power consumption during the half bridge operation becomes smaller than the power consumption in the above full bridge operation. Along with this, the magnetic energy generated by the power supply coil L1 in the half bridge operation is also smaller than the magnetic energy generated by the power supply coil L1 in the full bridge operation. Therefore, even if a plurality of power supply coils L1 that are close to each other simultaneously perform power supply and presence detection, the magnetic energy from the power supply coil L1 accompanying the detection is interfered with the magnetic energy from the power supply coil L1 accompanying the power supply. Will be suppressed. Therefore, by performing the presence detection, it is possible to suppress the power supply efficiency of the plurality of power supply coils L1 that are disposed close to each other.

(2) In the standby state in which neither the power supply nor the presence detection is performed, only the FET 2L is turned on, and the other three FETs 1H, 2H, and 1L are turned off. In this state, the power supply coil L1 is electrically blocked from the power supply Vdd. Therefore, for example, when a circuit having a low impedance on the power supply Vdd side exists, the current induced by the specific power supply coil L1 flows into the circuit direction in accordance with the magnetic energy from the power supply coil L1 located around the specific power supply coil L1. Further, by turning off the FET 1L, the regenerative current is generated via the FET 2L, the power supply coil L1, and the FET 1L. As described above, in the standby state, the magnetic connection with the power supply coil L1 located in the periphery can be suppressed by merely turning on the FET 2L. When power is supplied to the power supply coil L1 located around the specific power supply coil L1, the power supply efficiency of the power supply coil L1 can be suppressed from being lowered. Further, when the power supply coil L1 located around the specific power supply coil L1 performs presence detection, it is suppressed that the detection accuracy is lowered.

(3) In the presence detection, the time during which the FET 1L is turned on is set such that the time during which the FET 1L is turned on is longer than the time when the FET 1L is turned off. Further, the time during which the FET 1H is turned off is set such that the time during which the FET 1H is turned off is longer than the time when the FET 1H is turned off. In the half-bridge operation, for power supply The power supply of the coil L1 is limited to a period in which the FET 1L is in the off state and the FET 1H is in the on state. By adjusting the period, the power consumption during the half bridge operation can be adjusted.

(4) The magnetic energy from the power supply coil L1 accompanying the presence detection can be reduced. Therefore, it is possible to suppress an object that is a subject of detection from being subjected to an induced current to increase the temperature.

Further, the above embodiment can be implemented by the following aspects which are appropriately changed.

‧ In the above embodiment, only the FET 2L is turned on in the standby state, but the same effect can be obtained only by turning on the FET 1L.

Further, in the standby state, the two FETs 1L and 2L on the ground side can be turned on, and the two FETs 1H and 2H on the power supply Vdd side can be turned off. In this case, the induced current is also suppressed from flowing into the power supply Vdd side.

In the above embodiment, the ID comparison is performed by load modulation. However, the two circuits for authentication may be provided in the power supply device 10 and the power receiving device 30, and the ID may be compared by transmission and reception of the wireless signal. Also, the ID comparison can be omitted. At this time, the authentication signal generating circuit 41 and the load modulation circuit 42 can be omitted.

‧ The configuration for detecting foreign matter in the above embodiment (the foreign object detecting circuit 21, the two foreign object detecting coils L2, L4, the rectifier circuit 36, the oscillating device 37, and the like) may be omitted.

In the above embodiment, the power receiving device 30 is provided in the mobile terminal device 40, but may be provided in another electronic device. For example, the power receiving device 30 may be configured to be independent of the body of the electronic device.

‧ The unit control circuit 19 in the above embodiment can also be omitted. At this time, the common control circuit 12 also performs the control executed by the unit control circuit 19 in the above embodiment. Further, the common control circuit 12 may be caused to perform a part of the control by the unit control circuit 19, or the unit control circuit 19 may perform a part of the control by the common control circuit 12.

In the above embodiment, the EM drive circuit 16 uses an FET as a switching element, but other switching elements may be used.

In the above embodiment, the load ratio of the signal (Hi level) output to the FET 1L is set to a value exceeding 50% in the half bridge operation. However, the duty ratio can also be set to less than 50%. In this case, the FET1H will not be turned off during the off state. The power supply Vdd supplies electric power to the power supply coil L1. Therefore, the power consumption of the half bridge operation in the same manner as in the above embodiment is lower than that of the full bridge operation, and the power supply efficiency is suppressed from being lowered.

In the above embodiment, the power supply coil L1 and the capacitor C are connected in series, but the power supply coil L1 and the capacitor C may be connected in parallel. Also, the capacitor C can be omitted.

‧ In the above embodiment, metal detection can also be performed simultaneously when detecting presence. When the presence detection is performed as described above, the current change of the power supply coil L1 due to the impedance change due to the presence of the object placed on the power supply surface 6 is detected. For example, when the power receiving device 30 having the power receiving coil L3 is placed on the power feeding surface 6, the secondary side load observed from the power feeding coil L1 is increased, so that the current value flowing through the power feeding coil L1 is small, and the signal is received. The voltage level (the presence detection level) of the extraction circuit 17 becomes small. In addition, when the metal is placed on the power supply surface 6, the secondary side load observed from the power supply coil L1 is reduced, so that the current value flowing through the power supply coil L1 is larger than the case where the power receiving device 30 is provided as described above. And the presence detection level becomes higher. In the metal detection, the load characteristics differ depending on the type or size of the metal, and the detection level becomes a value different from the state in which the power supply surface 6 of the corresponding power supply coil L1 is not provided. There is a magnitude relationship between the detection level and the type of the object provided on the power supply surface 6, for example, the following.

"There is a power receiving device 30<No power receiving device 30 (no load) <With metal"

Consider this size relationship to consider setting the majority threshold. Thereby, the unit control circuit 19 can perform metal detection when there is detection via the presence detection level and the comparison of the threshold values. In this way, the metal detection can be performed without using the foreign matter detecting circuit such as the primary foreign object detecting coil L2 and the secondary foreign object detecting coil L4, so that the above-described embodiment can be omitted for detecting foreign matter such as metal. The configuration is the foreign matter detecting circuit 21, the signal extracting circuit 22, the coils L2 and L4, the rectifying circuit 36, the oscillating device 37, and the like. Thereby, the contactless power supply system can be constructed more simply.

In addition, in terms of the type of metal, copper, aluminum, iron, stainless steel, and the like are considered. When the metal types are different, the detection level changes depending on the difference in the degree of bonding of the power supply coil L1. Therefore, the threshold for metal detection must be determined by the type of metal.

Also, it can be used in most secondary machines with different loads (for example, mobile terminal 40) When present, it is detected which two-time machine is based on the presence of the detection level.

1H, 1L, 2H, 2L‧‧‧FET (Field Effect Transistor)

5‧‧‧Shell

6‧‧‧Power supply surface

10‧‧‧Power supply unit

11‧‧‧Common unit

12‧‧‧Common control circuit

13‧‧‧Power circuit

14‧‧‧ memory

15‧‧‧Power supply unit

16‧‧‧Excitation drive circuit

16a‧‧‧1st gate driver

16b‧‧‧2nd gate driver

17, 22‧‧‧ signal extraction circuit

19‧‧‧Unit control circuit

21‧‧‧ Foreign object detection circuit

24‧‧‧ memory

25‧‧‧Envelope detection circuit

26‧‧‧ Wave shaping circuit

27‧‧‧ Current detection circuit

30‧‧‧Power-receiving device

31‧‧‧Rectifier circuit

33‧‧‧Control circuit (2nd side control circuit)

35‧‧‧DC/DC converter

36‧‧‧Rectifier circuit

37‧‧‧Resonator

38‧‧‧load

39‧‧‧Optoelectronics

40‧‧‧Mobile terminal

41‧‧‧Signal generation circuit for authentication

42‧‧‧Load modulation circuit

A1~A3‧‧‧ connection line

Vdd‧‧‧ power supply

C‧‧‧ capacitor

L1‧‧‧Power supply coil

L2‧‧‧1 side foreign body detection coil

L3‧‧‧Power coil

L4‧‧‧2 side foreign body detection coil

Figure 1 is a block diagram of a contactless power supply system.

2 is a perspective view of a power supply device.

Fig. 3 is a view showing the configuration of an excitation drive circuit and a signal extraction circuit.

Fig. 4 is a waveform diagram of signals outputted to the respective FETs during power supply (when fully bridged).

Fig. 5 is a waveform diagram of signals outputted to respective FETs during detection (half-bridge operation).

Fig. 6 is a view showing the configuration of an excitation drive circuit and a signal extraction circuit.

Fig. 7 is a waveform diagram of signals outputted to the respective FETs when standby.

Fig. 8 is a flow chart showing the processing sequence of the common control circuit.

1H, 1L, 2H, 2L‧‧‧FET (Field Effect Transistor)

16‧‧‧Excitation drive circuit

16a‧‧‧1st gate driver

16b‧‧‧2nd gate driver

17‧‧‧Signal extraction circuit

19‧‧‧Unit control circuit

25‧‧‧Envelope detection circuit

26‧‧‧ Wave shaping circuit

27‧‧‧ Current detection circuit

A1~A3‧‧‧ connection line

Vdd‧‧‧ power supply

C‧‧‧ capacitor

L1‧‧‧Power supply coil

Claims (5)

A contactless power supply device includes a power supply surface for setting a power receiving device and a plurality of power supply units disposed along the power supply surface, so that at least one power supply unit of the plurality of power supply units generates magnetic flux and uses the borrowed The power receiving device is supplied to the power receiving device in a non-contact manner by electromagnetic induction of the magnetic flux. The power supply unit includes a first power supply side switching element and a first ground side switching element, and is connected in series to the power supply and the ground. The second power supply side switching element and the second ground side switching element are connected in series between the power supply and the ground; the power supply coil is operatively connected to the first power supply side switching element and the first ground side switching element a first connection point between the second power supply side switching element and the second connection point between the second ground side switching elements; and an excitation drive circuit that turns the switching elements on and off to supply the power supply Generating a magnetic flux by exciting the coil; and detecting a portion for detecting an object disposed on the power supply surface according to the current or voltage of the power supply coil; the excitation drive circuit is When the device is powered, the group of the first power source side switching element and the second ground side switching element, and the group of the second power source side switching element and the first ground side switching element are alternately turned on and off. When the presence detecting unit detects the presence or absence of an object, the excitation driving circuit alternately turns on the first power supply side switching element and the first ground side switching element, and fixes the second power supply side switching element. The second ground-side switching element is fixed in an on state. The non-contact power supply device according to claim 1, wherein when the presence detecting unit detects the presence or absence of an object, the first power supply side switching element and the first ground side switching element are alternately turned on and off. The on-time of the first ground-side switching element is set such that the on-time of the first ground-side switching element is longer than the off-time. A non-contact power supply device according to claim 1 or 2, wherein The excitation drive circuit cuts the first and second power supply side switching elements in a standby state in which neither detection nor power supply is performed. The non-contact power supply device of claim 3, wherein the excitation drive circuit turns on only one of the first and second ground-side switching elements in the standby state, and connects the first power supply side The switching element is disconnected from the second power supply side switching element. The non-contact power supply device of claim 1 or 2, wherein the presence detecting unit detects whether an object disposed on the power supply surface is metal based on a current or a voltage of the power supply coil.