JP6555401B2 - Electronic device, power supply system, and non-contact power supply method - Google Patents

Description

The present disclosure relates to a power supply system and a non-contact power supply method that perform non-contact power supply (power supply, power transmission, power transmission) to a power supply target device such as an electronic device, and an electronic device applied to such a power supply system. .

  In recent years, power supply systems (contactless power supply systems, wireless charging systems) that supply power in a non-contact manner to CE devices (consumer electronics devices) such as mobile phones and portable music players have attracted attention in recent years. Yes. Thus, charging is not started by inserting (connecting) a connector of a power supply device such as an AC adapter into the device, and the electronic device (secondary device) is placed on the charging tray (primary device). Just start charging. That is, terminal connection between the electronic device and the charging tray becomes unnecessary.

  The method of supplying power in a non-contact manner in this way is roughly divided into two types. The first method is an electromagnetic induction method that is already widely known. Since the degree of coupling between the power transmission side (primary side) and the power reception side (secondary side) is very high, high efficiency power feeding is possible. Is possible. The second method is a method called a magnetic field resonance method and has a feature that the magnetic flux shared between the power transmission side and the power reception side may be small by positively using the resonance phenomenon.

  Here, the non-contact power feeding system as described above is disclosed in, for example, Patent Documents 1 to 6 and the like.

JP 2001-102974 A WO00-27531 JP 2008-206233 A JP 2002-34169 A JP 2005-110399 A JP 2010-63245 A

  By the way, in the non-contact power supply system as described above, in general, the load in the electronic device that is the power supply target varies depending on the power supply and charging conditions. Therefore, it is desired to propose a method capable of performing appropriate control in response to load fluctuations when power is supplied using a magnetic field.

The present disclosure has been made in view of the above problems, and its object is appropriate control can be performed for electronic devices when performing non-contact power supply to provide a power supply system and the non-contact power feeding method.

The electronic device according to the present disclosure includes a power receiving unit that receives power that is contactlessly fed from a power feeding device, and a control unit. The control unit performs current increase control so that the power reception current supplied from the power reception unit is equal to or greater than a predetermined current value during a period in which standby power supply that is lower in power than the main power supply is performed from the power supply device .

The power supply system of the present disclosure includes one or a plurality of the electronic devices of the present disclosure and a power supply device that performs non-contact power supply to the electronic devices.
The non-contact power feeding method of the present disclosure performs non-contact power feeding from a power feeding device to one or a plurality of power feeding target devices, and standby power feeding that is lower power than main power feeding from the power feeding device to the power feeding target device. In the period to be performed, the current increase control is performed in the power supply target device so that the received current obtained by the non-contact power supply becomes a predetermined current value or more.

In the electronic device , the power feeding system, and the non-contact power feeding method according to the present disclosure, current increase control is performed so that the received current is equal to or higher than a predetermined current value during a period in which preliminary power feeding that is lower in power than the main power feeding is performed. . As a result, the received voltage can be appropriately controlled even during the preliminary power supply period .

Electronic device of the present disclosure, according to the power supply system and the non-contact power feeding method, in a period where the preliminary feeding is performed, since the power receiving current is to perform the current increase control so that the above predetermined current value, the Even during the preliminary power supply period , the received voltage can be easily controlled appropriately. Therefore, it is possible to perform appropriate control when performing non-contact power feeding. Note that the effects described here are not necessarily limited, and may be any effects described in the present disclosure.

It is a perspective view showing the example of appearance composition of the electric supply system concerning one embodiment of this indication. It is a figure showing the detailed structural example of the electric power feeding system shown in FIG. FIG. 3 is a circuit diagram illustrating a detailed configuration example of an AC signal generation circuit illustrated in FIG. 2. It is a timing waveform diagram showing an example of a control signal for an AC signal generation circuit. FIG. 4 is a circuit diagram schematically illustrating an operation example of the AC signal generation circuit illustrated in FIG. 3. FIG. 4 is a circuit diagram schematically illustrating another operation example of the AC signal generation circuit illustrated in FIG. 3. FIG. 3 is a circuit diagram illustrating a detailed configuration example of a dummy load circuit illustrated in FIG. 2. FIG. 7 is a circuit diagram schematically illustrating a state example of a dummy load circuit illustrated in FIG. 6. It is a characteristic view showing an example of the relationship between the phase difference in an alternating current signal generation circuit, a received voltage, and load resistance. It is a characteristic view for demonstrating the influence of a harmonic. It is a flowchart showing an example of the electric power feeding / charging operation | movement which concerns on embodiment. It is a flowchart showing an example of the electric power feeding and charging operation following FIG. It is a figure showing an example of the operation state in the case of preliminary electric power feeding. It is a figure showing an example of the relationship between a receiving current and the connection state of a dummy load. FIG. 7 is a circuit diagram schematically illustrating another example of the dummy load circuit illustrated in FIG. 6. FIG. 7 is a circuit diagram schematically illustrating another example of the dummy load circuit illustrated in FIG. 6. FIG. 7 is a circuit diagram schematically illustrating another example of the dummy load circuit illustrated in FIG. 6. 10 is a flowchart illustrating an example of a dummy load separation process according to Modification Example 1. It is a figure showing an example of the relationship between the receiving current which concerns on the modification 2, and the connection state of a dummy load. 10 is a diagram illustrating a configuration example of a power feeding system according to Modification 3. FIG. FIG. 19 is a block diagram illustrating a configuration example of a current increase control unit illustrated in FIG. 18. FIG. 20 is a circuit diagram illustrating a configuration example of a current increase control unit illustrated in FIG. 19. FIG. 21 is a circuit diagram illustrating a detailed configuration example of a current increase control unit illustrated in FIG. 20. FIG. 21 is a circuit diagram illustrating another detailed configuration example of the current increase control unit illustrated in FIG. 20. FIG. 20 is a block diagram illustrating a state example of a current increase control unit illustrated in FIG. 19. FIG. 20 is a block diagram illustrating another state example of the current increase control unit illustrated in FIG. 19. FIG. 10 is a characteristic diagram illustrating an example of an actual measurement result according to Modification 3. It is a characteristic view showing the other example of the measurement result which concerns on the modification 3. It is a figure showing an example of the relationship between the reference voltage which concerns on the modification 3, and each parameter. 10 is a circuit diagram illustrating a configuration example of a current increase control unit according to Modification 4. FIG.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.
1. Embodiment (example in which the received current is increased using a dummy load)
2. Modified example Modified example 1 (example in which the disconnection of the dummy load is determined according to the magnitude of the received current)
Modification 2 (Example in which a plurality of types of dummy loads are selectively used according to the magnitude of the received current)
Modified examples 3 and 4 (examples in which received current is increased using a comparator, an integrator, etc.)
3. Other variations

<Embodiment>
[Overall configuration of power supply system 4]
FIG. 1 illustrates an external configuration example of a power feeding system (power feeding system 4) according to an embodiment of the present disclosure. FIG. 2 is a block diagram and a circuit diagram illustrating a detailed configuration example of the power feeding system 4. It is a representation. The power feeding system 4 is a system (non-contact type power feeding system) that performs power transmission (power supply, power feeding, power transmission) in a non-contact manner using a magnetic field (using magnetic field resonance, electromagnetic induction, etc .; the same applies hereinafter). is there. The power supply system 4 includes a power supply device 1 (primary device) and one or a plurality of electronic devices (here, one electronic device 2; a secondary device) as power supply target devices.

  In the power supply system 4, for example, as illustrated in FIG. 1, the electronic device 2 is placed on (or close to) the power supply surface (power transmission surface) S <b> 1 of the power supply device 1, whereby the power supply device 1 changes to the electronic device 2. On the other hand, power transmission is performed. Here, as an example, the power supply device 1 has a mat shape (tray shape) in which the area of the power supply surface S1 is larger than that of the electronic device 2 to be supplied with power.

(Power supply device 1)
As described above, the power supply device 1 is a device (charging tray) that supplies power to the electronic device 2 using a magnetic field. For example, as illustrated in FIG. 2, the power supply device 1 includes a power transmission unit 10, an AC signal generation circuit (AC signal generation unit, high-frequency power generation circuit) 11, a communication unit 12, and a control unit 13.

  The power transmission unit 10 includes a power transmission coil (primary coil) L1, a capacitor C1 (resonance capacitor), and the like. These power transmission coil L1 and capacitor C1 are electrically connected in series with each other. Specifically, one end of the power transmission coil L1 is connected to one end of the capacitor C1, the other end of the power transmission coil L1 is grounded, and the other end of the capacitor C1 is connected to the output terminal of the AC signal generation circuit 11. The power transmission unit 10 uses the power transmission coil L1 and the capacitor C1 to supply power to the electronic device 2 (specifically, a power reception unit 20 described later) using an alternating magnetic field (in FIG. 2). Arrow P1). Specifically, the power transmission unit 10 has a function of radiating a magnetic field (magnetic flux) from the power feeding surface S <b> 1 toward the electronic device 2.

  In the power transmission unit 10, an LC resonance circuit is configured by using the power transmission coil L1 and the capacitor C1. An LC resonance circuit formed in the power transmission unit 10 and an LC resonance circuit formed in the power reception unit 20 described later are magnetically coupled to each other (mutual induction).

  The AC signal generation circuit 11 generates a predetermined AC signal Sac (high frequency power) for performing power supply using, for example, power (DC signal Sdc) supplied from an external power supply 9 (parent power supply) of the power supply apparatus 1. Circuit. The AC signal Sac is supplied to the power transmission unit 10. The external power supply 9 is, for example, a USB (Universal Serial Bus) 2.0 power supply (power supply capacity: 500 mA, power supply voltage: about 5 V) provided in an ordinary AC adapter, a PC (Personal Computer), or the like. ) And the like.

  Such an AC signal generation circuit 11 includes a switching amplifier (so-called class E amplifier, differential amplifier, etc.) including one or a plurality of switching elements SW1 made of, for example, a MOS (Metal Oxide Semiconductor) transistor, as will be described later. It is comprised using. Further, a power supply control signal CTL1 is supplied from the control unit 13 to the switching element SW1. The detailed configuration of the AC signal generation circuit 11 will be described later.

  The communication unit 12 performs a predetermined communication operation with a communication unit 26 (described later) in the electronic device 2 (see arrow C1 in FIG. 2).

  The control unit 13 performs various control operations in the entire power supply apparatus 1 (the entire power supply system 4). Specifically, in addition to controlling power transmission operation by the power transmission unit 10 and communication operation by the communication unit 12, for example, optimization control of power supply power, a function for authenticating power supply target devices, and power supply target devices are in the vicinity. A function for detecting this, and a function for detecting the mixing of dissimilar metals. Here, at the time of controlling the power feeding operation described above, the operation of the AC signal generating circuit 11 is controlled using the control signal CTL1 described above. Such a control part 13 is comprised using the microcomputer, the pulse generator, etc., for example. The details of the control operation of the AC signal generation circuit 11 by the control unit 13 will be described later.

(Electronic equipment 2)
The electronic device 2 includes, for example, a stationary electronic device represented by a television receiver, a portable electronic device including a rechargeable battery (battery) represented by a mobile phone or a digital camera, and the like. For example, as illustrated in FIG. 2, the electronic device 2 includes a power reception unit 20, a rectifier circuit 21, a current detection unit 22, a dummy load circuit 23, a charging unit 24, a battery 25, a communication unit 26, a control unit 27, and a memory unit. 28. The dummy load circuit 23 corresponds to a specific example of “current increasing unit” in the present disclosure.

  The power receiving unit 20 includes a power receiving coil (secondary coil) L2, capacitors C2s and C2p (resonance capacitors), and the like. The power receiving coil L2 and the capacitor C2s are electrically connected in series with each other, and the power receiving coil L2 and the capacitor C2p are electrically connected in parallel with each other. Specifically, one end of the capacitor C2s is connected to one input terminal of the rectifier circuit 21 and one end of the capacitor C2p, and the other end of the capacitor C2s is connected to one end of the power receiving coil L2. The other end of the power receiving coil L2 is connected to the other input terminal of the rectifier circuit 21 and the other end of the capacitor C2p. The power receiving unit 20 has a function of receiving power (feed power) transmitted from the power transmitting unit 10 in the power feeding apparatus 1 using the power receiving coil L2 and the capacitors C2s and C2p.

  In the power reception unit 20, an LC resonance circuit is configured by using the power reception coil L2 and the capacitors C2s and C2p. The LC resonance circuit formed in the power reception unit 20 and the LC resonance circuit formed in the power transmission unit 10 are magnetically coupled to each other as described above. As a result, LC resonance operation is performed at substantially the same resonance frequency as the high-frequency power (AC signal Sac) generated by the AC signal generation circuit 11.

  The rectifier circuit 21 is a circuit that rectifies the received voltage (AC voltage) supplied from the power receiving unit 20 to generate a DC voltage. In other words, the rectifier circuit 21 rectifies the AC received current (AC received current Iac) and the received voltage (AC received voltage Vac) supplied from the power receiving unit 20, and receives the DC received current (DC received current Idc) and received power. A voltage (DC receiving voltage Vdc) is generated. The rectifier circuit 21 is, for example, a bridge-structure circuit using a plurality of rectifier elements (diodes). The rectifier circuit 21 may be a synchronous rectifier circuit using a transistor, for example.

  The current detection unit 22 detects a power reception current supplied from the power reception unit 20. In particular, in this example, the current detection unit 22 detects the received current (DC received current Idc) after rectification by the rectifier circuit 21 on the rear stage side of the rectifier circuit 21 on the power supply line Lp. The DC receiving current Idc detected in this way is output to the control unit 27. Such a current detection unit 22 is configured using, for example, a resistor or a current transformer.

  The dummy load circuit 23 is disposed between the rectifier circuit 21 and the charging unit 24 on the power supply line Lp, and includes one or a plurality of dummy loads (dummy resistors or the like). The dummy load circuit 23 increases the received current (in this example, the DC received current Idc) according to the control (control signal CTL2) from the control unit 27 when a predetermined condition described later is satisfied (current increasing operation). ). The detailed configuration of the dummy load circuit 23 and the details of the current increasing operation will be described later.

  The charging unit 24 performs a charging operation for the battery 25 as the main load based on the DC power output from the rectifier circuit 21.

  The battery 25 stores electric power according to the charging operation by the charging unit 24, and is configured using a rechargeable battery (secondary battery) such as a lithium ion battery, for example.

  The communication unit 26 performs the above-described predetermined communication operation with the communication unit 12 in the power supply apparatus 1 (see arrow C1 in FIG. 2).

  The control unit 27 performs various control operations in the entire electronic device 2 (the entire power feeding system 4). Specifically, in addition to controlling the power reception operation by the power reception unit 20 and the communication operation by the communication unit 26, for example, a function of performing optimization control of received power and controlling the charging operation of the charging unit 24 Etc.

  Here, in the present embodiment, the control unit 27 is configured such that the received current (DC received current Idc) detected by the current detector 22 is less than a predetermined threshold current Ith at a light load described later (Idc < For Ith), the following current increase control is performed. Specifically, in such a case, the control unit 27 performs current increase control so that the DC received current Idc increases to a threshold current Ith or more (Idc ≧ Ith). More specifically, the control unit 27 performs such current increase control by using at least one of the dummy loads in the dummy load circuit 23 described above, for example. Such a control part 27 is comprised using the microcomputer etc., for example. The details of the current increase control operation by the control unit 27 will be described later.

  The memory unit 28 is for storing various information used in the control unit 27. Specifically, for example, information on the threshold current Ith described above is stored.

[Detailed Configuration Example of AC Signal Generating Circuit 11]
Next, a detailed configuration example of the above-described AC signal generation circuit 11 will be described with reference to FIGS. 3, 4, 5 </ b> A, and 5 </ b> B. FIG. 3 shows an example of the circuit configuration of the AC signal generation circuit 11 together with the external power source 9, the power transmission unit 10, and the control unit 13.

  In this example, the AC signal generation circuit 11 has a bridge circuit configuration using the four switching elements SW1a, SW1b, SW1c, and SW1d as the switching element SW1 described above. Further, these switching elements SW1a, SW1b, SW1c, SW1d are each composed of a MOS transistor in this example. In the AC signal generation circuit 11, the control signals CTL1a, CTL1b, CTL1c, and CTL1d as the control signal CTL1 described above are individually input to the gates of the switching elements SW1a, SW1b, SW1c, and SW1d, respectively. Yes. A connection line from the external power supply 9 is connected to the sources of the switching elements SW1a and SW1c. The drain of the switching element SW1a is connected to the drain of the switching element SW1b, and the drain of the switching element SW1c is connected to the drain of the switching element SW1d. The sources of the switching elements SW1b and SW1d are each connected to the ground (ground). The drains of the switching elements SW1a and SW1b are each connected to one end of the capacitor C1 in the power transmission unit 10, and the drains of the switching elements SW1c and SW1d are each connected to one end of the power transmission coil L1 in the power transmission unit 10. .

  For example, as shown in FIG. 4, the control signal CTL1 (CTL1a, CTL1b, CTL1c, CTL1d) has a predetermined frequency f (CTL1 (f) = f1) and a duty ratio Duty (CTL1 (Duty) = 10%, 50%, etc.). Also, as shown in FIG. 4, the pulse width modulation (PWM) is performed by controlling the duty ratio Duty in the control signal CTL1.

  With this configuration, in the AC signal generation circuit 11, the switching elements SW1a, SW1b, SW1c, and SW1d are turned on / off (switching operation having a frequency f and a duty ratio Duty) according to the control signals CTL1a, CTL1b, CTL1c, and CTL1d )I do. That is, the on / off operation of the switching element SW1 is controlled using the control signal CTL1 supplied from the control unit 13. Thereby, for example, the AC signal Sac is generated based on the DC signal Sdc input from the external power supply 9 side, and is supplied to the power transmission unit 10.

  In the AC signal generation circuit 11, the circuit configuration between the full bridge circuit and the half bridge circuit can be switched as follows in accordance with the control signals CTL1a, CTL1b, CTL1c, and CTL1d. Thereby, it is possible to change the voltage at the time of power feeding according to the control of the switching operation without changing the hardware configuration.

  Specifically, as shown in FIG. 5A, for example, when each of the four switching elements SW1a, SW1b, SW1c, and SW1d performs an on / off operation, a full bridge circuit is configured.

  For example, as shown in FIG. 5B, when the two switching elements SW1a and SW1b perform on / off operations, respectively, while the switching element SW1c is always in the off state and the switching element SW1d is always in the on state, become that way. That is, in this case, this is equivalent to the configuration of a half bridge circuit composed of two switching elements SW1a and SW1b. Therefore, in this case, compared to the full bridge circuit shown in FIG. 5A, the voltage (power supply voltage) generated by the AC signal generation circuit 11 at the time of power supply is about ½. In these FIGS. 5A and 5B and similar drawings thereafter, each switching element is schematically shown in the form of a switch for easy understanding of the operation state.

[Detailed Configuration Example of Dummy Load Circuit 23]
Next, a detailed configuration example of the above-described dummy load circuit 23 will be described with reference to FIGS. FIG. 6 shows an example of the circuit configuration of the dummy load circuit 23 together with the control unit 27.

  In this example, the dummy load circuit 23 includes two dummy loads Ra and Rb made of resistance elements (dummy resistors) and two switching elements SW2a and SW2b made of MOS transistors. The dummy load Ra and the switching element SW2a are connected in series between the power supply line Lp and the ground line, and the dummy load Rb and the switching element SW2b are connected in series between the power supply line Lp and the ground line. Has been. Specifically, one end of the dummy load Ra is connected to the power supply line Lp, the other end of the dummy load Ra is connected to the drain of the switching element SW2a, and the source of the switching element SW2a is connected to the ground line. Similarly, one end of the dummy load Rb is connected to the power supply line Lp, the other end of the dummy load Rb is connected to the drain of the switching element SW2b, and the source of the switching element SW2b is connected to the ground line. The element pair of the dummy load Ra and the switching element SW2a and the element pair of the dummy load Rb and the switching element SW2b are arranged in parallel to each other. The control signals CTL2a and CTL2b as the control signal CTL2 described above are individually input to the gates of the switching elements SW2a and SW2b.

  With this configuration, the dummy load circuit 23 is set so that the two switching elements SW2a and SW2b are individually turned on or off in accordance with the control signals CTL2a and CTL2b supplied from the control unit 27. As a result, in the dummy load circuit 23, the two dummy loads Ra and Rb are individually connected or disconnected between the supply paths of the DC receiving current Idc (between the power supply line Lp and the ground line). It is like that.

  For example, as shown in FIG. 7, the switching elements SW2a and SW2b are both set to be in an off state except during the light load described above (except when satisfying (Idc <Ith) described later). That is, both dummy loads Ra and Rb are set so as not to be connected to the supply path of the DC receiving current Idc.

[Operation and effect of power feeding system 4]
(1. Overview of overall operation)
In the power supply system 4, the AC signal generation circuit 11 in the power supply apparatus 1 performs power transmission to the power transmission coil L <b> 1 and the capacitor C <b> 1 in the power transmission unit 10 based on the power supplied from the external power supply 9. Predetermined high frequency power (AC signal Sac) is supplied. Thereby, a magnetic field (magnetic flux) is generated in the power transmission coil L <b> 1 in the power transmission unit 10. At this time, when the electronic device 2 as a power supply target device is placed (or close) on the upper surface (power supply surface S1) of the power supply device 1, the power transmission coil L1 in the power supply device 1 and the power reception coil L2 in the electronic device 2 are placed. Are close to each other in the vicinity of the feeding surface S1.

  As described above, when the power receiving coil L2 is disposed in the vicinity of the power transmitting coil L1 that generates a magnetic field, the power is induced by the magnetic flux generated from the power transmitting coil L1, and an electromotive force (induced electromotive force is generated in the power receiving coil L2. ) Occurs. In other words, a magnetic field is generated by interlinking with each of the power transmission coil L1 and the power reception coil L2 by electromagnetic induction or magnetic field resonance. As a result, power is transmitted from the power transmission coil L1 side (primary side, power supply device 1 side, power transmission unit 10 side) to the power reception coil L2 side (secondary side, electronic device 2 side, power reception unit 20 side). (See arrow P1 in FIG. 2). At this time, the power transmission coil L1 on the power feeding device 1 side and the power reception coil L2 on the electronic device 2 side are magnetically coupled to each other by electromagnetic induction or the like, and LC resonance operation is performed.

  Then, in the electronic device 2, the AC power received by the power receiving coil L <b> 2 is supplied to the charging unit 24 via the rectifier circuit 21, and for example, the following charging operation is performed. That is, after the alternating voltage (alternating current) is converted into a predetermined direct current voltage (direct current) by the rectifier circuit 21, the charging unit 24 charges the battery 25 based on the direct current voltage. In this way, the electronic device 2 performs a charging operation based on the power received by the power receiving unit 20.

  That is, in the present embodiment, when charging the electronic device 2, for example, terminal connection to an AC adapter or the like is unnecessary, and charging is easily started simply by placing (making it close to) the power feeding surface 1 of the power feeding device 1. (Contactless power feeding is performed). This leads to a reduction in the burden on the user.

  In addition, during such an operation, a mutual communication operation is performed between the communication unit 12 in the power feeding device 1 and the communication unit 26 in the electronic device 2 (see arrow C1 in FIG. 2). Thereby, for example, mutual authentication between devices and power supply efficiency control are performed.

(2. Receiving current at light load)
By the way, in the electric power feeder 1 of this Embodiment, in the alternating current signal generation circuit 11, the electric power feeding control using PWM control as mentioned above is performed (refer FIG. 4). However, when power supply control by such PWM control is performed, the received power may not be properly controlled in the electronic device 2 at a light load as described below.

  In PWM control, changing the phase difference of the input to the switching element is generally equivalent to changing the duty ratio. As an example, an input phase difference = 90 ° corresponds to a duty ratio = 25%.

  Here, FIG. 8 shows an example of the relationship between the phase difference of the inputs to the switching elements SW1a to SW1d in the AC signal generation circuit 11, the DC received voltage Vdc and the load resistance in the electronic device 2. According to FIG. 8, when a certain amount of current (DC receiving current Idc) flows in the electronic device 2 (when the load resistance value is small to some extent), the DC receiving voltage Vdc also decreases as the phase difference decreases. ing. That is, in such a case, the phase difference and the DC received voltage Vdc are in a monotonically decreasing relationship. However, when the current flowing in the electronic device 2 decreases (when the value of the load resistance increases), these are no longer in a monotonically decreasing relationship.

  This is because when the DC receiving current Idc becomes small (when the load becomes light), the frequency component of the double resonance becomes easy to see in the electronic device 2 and the influence of the harmonic becomes large. Specifically, for example, as shown in FIG. 9, the ratio (ratio) between the fundamental wave component and the harmonic wave component is greatly different depending on the duty ratio, and the duty ratio of the fundamental wave component increases to 50%. However, the harmonic component does not increase monotonously. Therefore, for example, the case where the ratio of the specific harmonic component to a fundamental wave becomes high may arise. As described above, when double resonance occurs in the electronic device 2, if the load becomes light (the value of the DC receiving current Idc becomes small), the influence of the harmonics becomes large, and the receiving voltage at the time of the feeding power by the PWM control becomes large. It may be difficult to adjust (DC receiving voltage Vdc, etc.). In other words, due to a light load in the electronic device 2, there is a possibility that the DC received voltage Vdc may be in an uncontrollable state, or the DC received voltage Vdc may become an overvoltage.

  Here, in the power supply system 4 of the present embodiment, as described later, the load in the electronic device 2 that is the power supply target varies depending on the power supply and charging conditions. Therefore, when power is supplied using a magnetic field, it is required to perform appropriate control corresponding to load fluctuations. Even in cases other than the power supply control using the PWM control as described above, if the load on the electronic device 2 becomes too light, the voltage control range in the power supply device 1 is narrow, which again causes the received voltage. It may be difficult to adjust (DC receiving voltage Vdc, etc.).

(3. Increase operation of receiving current)
Therefore, in the present embodiment, the above-described problem is solved in the electronic device 2 that is the secondary device as follows.

  That is, when the DC receiving current Idc detected by the current detection unit 22 at the time of light load is less than a predetermined threshold current Ith (Idc <Ith), Perform current increase control. Specifically, in such a case, the control unit 27 performs current increase control so that the DC received current Idc increases to a threshold current Ith or more (Idc ≧ Ith). More specifically, the control unit 27 performs such current increase control using at least one of the dummy loads in the dummy load circuit 23. Hereinafter, a series of power feeding / charging operations including such current increase control will be described in detail.

  Here, as the “light load” described above, for example, the following two periods are assumed. That is, first, there is a period before connection of the battery 25 as the main load (preliminary power supply period at start-up described later: first period). In addition, a period of a charging operation to the battery 25 based on the main power supply described later (for example, a period near full charge: the second period) after the connection of the battery 25 can be given.

  Therefore, in this embodiment, as will be described in detail below, whether or not the load is light in both the standby power supply period and the charging operation period (the DC received current Idc is less than the threshold current Ith). Whether or not) is determined. Further, as will be described later, during the period of the charging operation, it is periodically determined whether or not it is such a light load. When it is determined that the load is light, the current increase control described above is performed.

  FIG. 10 and FIG. 11 are flowcharts showing the power feeding / charging operation of the present embodiment. In this power feeding / charging operation, first, preliminary power feeding, which is lower in power than the main power feeding, is started from the power feeding device 1 to the electronic device 2 (step S101 in FIG. 10), and the received power obtained by this preliminary power feeding is started. Is used to activate the electronic device 2 (step S102).

  Next, the received power for the main power supply is determined in the electronic device 2 (control unit 27) by communication between the power supply device 1 and the electronic device 2 (step S103). Note that, during this preliminary power supply, the necessary power supply is lower than that of the main power supply, so the AC signal generation circuit 11 in the power supply apparatus 1 is set to a half-bridge circuit.

  Here, at the time of such preliminary power feeding, for example, as shown in FIG. 12, the control unit 27 controls the charging unit 24 to be in a non-operating state, so that this load (battery 25 in this example) is powered. The connection line Lp is set so as to be disconnected.

  Next, in the electronic device 2, before the power supply device 1 is notified of the request for starting the main power supply based on the received power determined in step S103 (step S106 described later), the current detection unit 22 performs the preliminary power supply. Is detected (step S104). Then, the control unit 27 determines whether or not the detected DC receiving current Idc is less than a predetermined threshold current Ith (Idc <Ith) (step S105). Note that the DC receiving current Idc at the time of this preliminary power supply can be estimated and estimated in advance as a consumption current in an IC (Integrated Circuit), unlike a charging operation described later. Therefore, in steps S104 and S105 described above, instead of the current detected by the current detection unit 22, the value estimated and set in advance is read from, for example, the memory unit 28 and used. Also good.

  The threshold current Ith is set to such a current value as described in FIG. 8 that avoids the possibility that the received voltage will be uncontrollable due to a light load or that the received voltage may become an overvoltage. The As an example, it is conceivable to set the threshold current Ith = about 100 mA. Further, the value of the threshold current Ith is not limited to a fixed value, and may be, for example, the following variable value (configuration in which the value can be changed). Specifically, for example, as indicated by an arrow P2 in FIG. 13, the value of the threshold current Ith depends on the magnitude of the received voltage (DC received voltage Vdc) supplied from the power receiving unit 20 and rectified. (For example, the load resistance value in the electronic device 2 is controlled to be a predetermined value or less).

  Here, when it is determined that the detected DC received current Idc is equal to or greater than the threshold current Ith (Idc ≧ Ith) (step S105: N), for example, the power received due to a light load as described in FIG. It can be said that there is no possibility of falling into a voltage uncontrollable state or a possibility that the received voltage becomes an overvoltage. Therefore, in this case, the current increase control described below is not performed, and the power supply start request is notified from the electronic device 2 to the power supply apparatus 1 using communication (step S106). That is, in this case, as shown in FIG. 7 described above, in the dummy load circuit 23, the dummy loads Ra and Rb are both set in a non-connected state between the supply paths of the DC receiving current Idc. (See current range A2 shown in FIG. 13).

  On the other hand, when it is determined that the detected DC receiving current Idc is less than the threshold current Ith (Idc <Ith) (step S105: Y), the current increase control is performed in the electronic device 2 as follows.

  That is, first, as shown in FIG. 14, for example, the control unit 27 converts at least one of the dummy loads Ra and Rb in the dummy load circuit 23 (in this example, only the dummy load Ra) into the DC received current Idc. (See step S107, current range A1 shown in FIG. 13). Specifically, the control unit 27 controls the switching element SW2a to be turned on and the switching element SW2b to be turned off. As a result, as shown in FIG. 14, the current Ia flows from the supply path (power supply line Lp) of the DC received current Idc to the dummy load Ra, and the DC received current Idc increases. In this way, increase control (current increase control) of the DC receiving current Idc is performed.

  After such current increase control is performed, the control unit 27 determines whether or not the DC received current Idc detected again is less than the threshold current Ith (Idc <Ith) (step S108). Here, when it is determined that the DC reception current Idc detected again is greater than or equal to the threshold current Ith (Idc ≧ Ith) (step S108: N), that is, the DC reception current Idc is greater than or equal to the threshold current Ith by current increase control. If it increases, the process proceeds to step S106 described above. In other words, the electronic device 2 notifies the power supply apparatus 1 of a request for starting the main power supply using communication. This is also because it can be said that there is no longer a possibility that the received voltage becomes uncontrollable due to a light load or that the received voltage becomes an overvoltage.

  On the other hand, when it is determined that the DC reception current Idc detected again is less than the threshold current Ith (Idc <Ith) (step S108: Y), that is, even if the current increase control is performed, the DC reception current Idc still remains. When the current is less than the threshold current Ith, the current increase control is performed again as follows. That is, the control unit 27 additionally connects the dummy load between the supply paths of the DC receiving current Idc in the dummy load circuit 23, or switches the dummy load to one having a larger load (for example, resistance value) ( Step S109). In addition, after such a current increase control again, it returns to step S108 again.

  Here, when the dummy load is additionally connected, specifically, for example, as shown in FIG. 15A. That is, in this example, the control unit 27 connects the dummy load Rb in addition to the dummy load Ra between the supply paths of the DC receiving current Idc. More specifically, the control unit 27 controls the switching elements SW2a and SW2b so that both are turned on. As a result, as shown in FIG. 15A, the currents Ia and Ib flow from the supply path of the DC received current Idc to the dummy loads Ra and Rb, respectively, and the DC received current Idc further increases. In this way, further increase control of the DC receiving current Idc is performed.

  On the other hand, when switching the dummy load to one having a larger load, specifically, for example, as shown in FIG. 15B. That is, in this example, when the load of the dummy load Rb is larger than that of the dummy load Ra, the control unit 27 connects the dummy load Rb between the supply paths of the DC receiving current Idc instead of the dummy load Ra. More specifically, the control unit 27 controls the switching element SW2a to be turned off and the switching element SW2b to be turned on. As a result, as shown in FIG. 15B, the current Ib flows from the supply path of the DC received current Idc to the dummy load Rb having a larger load, and the DC received current Idc further increases. In this way, further increase control of the DC receiving current Idc is performed.

  Here, after the notification of the start request of the main power supply to the power supply apparatus 1 side (step S106), the power supply apparatus 1 then supplies the electronic device 2 with higher power than the standby power supply. Power supply is started (step S110). In other words, in this main power supply, the AC signal generation circuit 11 in the power supply apparatus 1 is switched from the half bridge circuit to the full bridge circuit.

  When the main power supply is started in this way, the control unit 27 sets the battery 25 as the main load in the electronic device 2 to be connected to the power supply line Lp by switching the charging unit 24 to the operating state. (Step S111). In step S111, when the battery 25 is thus set in the connected state, the control unit 27 disconnects both the dummy loads Ra and Rb from the supply path of the DC received current Idc. Specifically, as shown in FIG. 7 described above, the control unit 27 controls the switching elements SW2a and SW2b to be turned off. As a result, the currents Ia and Ib do not flow to the dummy loads Ra and Rb, and the increase control of the DC receiving current Idc is stopped.

  Next, in the electronic device 2, the charging unit 24 performs a charging operation for the battery 25 based on the received power (main power supply) (step S112 in FIG. 11). Subsequently, the control unit 27 determines whether or not the battery 25 is fully charged by this charging operation (step S113). Here, when it is determined that the battery is fully charged (step S113: Y), the power supply / charge operation illustrated in FIGS. 10 and 11 is terminated.

  On the other hand, when it is determined that the battery is not fully charged (step S113: N), the control unit 27 subsequently determines that the DC receiving current Idc detected again during the charging operation is less than the threshold current Ith (Idc < It is determined whether or not (Ith) (step S114). Here, when it is determined that the DC received current Idc detected again is equal to or greater than the threshold current Ith (Idc ≧ Ith) (step S114: N), the current increase control described above is not performed, and the process returns to step S112. become.

  On the other hand, when it is determined that the DC received current Idc detected again is less than the threshold current Ith (Idc <Ith) (step S114: Y), the control unit 27 performs the above-described method (method for connecting a dummy load). The current increase control is performed at (Step S115). After such current increase control is performed, the control unit 27 determines again whether or not the DC received current Idc is less than the threshold current Ith (Idc <Ith) (step S116).

  Here, when it is determined that the DC received current Idc is equal to or greater than the threshold current Ith (Idc ≧ Ith) (step S116: N), that is, when the DC received current Idc is increased beyond the threshold current Ith by current increase control. Will return to step S112 described above.

  On the other hand, when it is determined that the DC receiving current Idc is less than the threshold current Ith (Idc <Ith) (step S116: Y), that is, even if the current increase control is performed, the DC receiving current Idc is still less than the threshold current Ith. In some cases: That is, the control unit 27 performs the current increase control again by the method described above (for example, the method shown in FIG. 15A or 15B). Specifically, the control unit 27 additionally connects the dummy load between the supply paths of the DC receiving current Idc in the dummy load circuit 23, or switches the dummy load to one having a larger load (step S117). ). In addition, after such a current increase control again, it returns to step S116 again.

  As described above, in the present embodiment, when the DC receiving current Idc at a light load is less than the predetermined threshold current Ith, the current increase control is performed so that the DC receiving current Idc increases to be equal to or greater than the threshold current Ith. Do. Thereby, even at such a light load, it is possible to easily control the power reception voltage (DC power reception voltage Vdc, etc.) in the electronic device 2 appropriately. Specifically, for example, as described in FIG. 8, it is possible to avoid the possibility that the received voltage becomes uncontrollable due to a light load or that the received voltage becomes an overvoltage. Therefore, appropriate control can be performed when power is supplied using a magnetic field.

<Modification>
Subsequently, modified examples (modified examples 1 to 4) of the above-described embodiment will be described. In addition, the same code | symbol is attached | subjected to the same thing as the component in embodiment, and description is abbreviate | omitted suitably.

[Modification 1]
FIG. 16 is a flowchart illustrating an example of the dummy load separation process according to the first modification. In the present modification, unlike the above-described embodiment, the control unit 27 sets the dummy load when the DC received current Idc is equal to or greater than the threshold current Ith (Idc ≧ Ith) after the battery 25 is set in the connected state. Is separated from the supply path of the DC receiving current Idc. That is, after the battery 25 is set in the connected state, the magnitude of the DC received current Idc is confirmed again, and then the dummy load is disconnected.

  Note that the process shown in FIG. 16 corresponds to, for example, the process of steps S111 and S112 described in the embodiment, and other processes in the series of power supply / charge operations according to this modification are as follows. Basically, it is the same as the embodiment.

  In the dummy load disconnecting process of the present modification, first, as in the case of the embodiment, when the battery 25 as the main load is connected in the electronic device 2 (step S201 in FIG. 16), the battery 25 is then connected. The charging operation is performed (step S202). However, in this modification, unlike the embodiment, the dummy load is not yet separated at this stage.

  Subsequently, the electronic device 2 determines again whether or not the DC received current Idc detected at this stage is less than the threshold current Ith (Idc <Ith) (step S203). Here, when it is determined that the detected DC receiving current Idc is less than the threshold current Ith (Idc <Ith) (step S203: Y), since the load is still light, the dummy load is still disconnected at this stage. Is not executed, and the process returns to step S202.

  On the other hand, when it is determined that the detected DC receiving current Idc is equal to or greater than the threshold current Ith (Idc ≧ Ith) (step S203: N), the control unit 27 next performs the disconnection of the dummy load. Control is performed as described above (step S204). Thus, the dummy load separation process illustrated in FIG. 16 is completed.

  In this way, in this modification, after the battery 25 is set in the connected state, the magnitude of the DC receiving current Idc is confirmed again, and then the dummy load is disconnected. In addition, for example, the following effects can be obtained. That is, first, when the battery 25 as the main load is set to the connected state, the main load becomes a heavy load. Therefore, it can be said that it is desirable to disconnect the dummy load at this point as in the embodiment. However, depending on the situation, it may be assumed that the load is still light after connection of the main load. Therefore, by adopting the method of the present modification described above, the dummy load separation timing can be appropriately controlled according to the situation. Therefore, more appropriate control can be performed when power is supplied using a magnetic field.

[Modification 2]
FIG. 17 shows an example of the relationship between the received current (DC received current Idc) and the connection state of the dummy load according to the second modification. In this modification, the dummy load circuit 23 has a plurality of types (in this example, three types) of dummy loads having different load sizes (resistance values and the like). When it is determined that the DC receiving current Idc is less than the threshold current Ith, the control unit 27 selects the type of dummy load selected from a plurality of types of dummy loads according to the magnitude of the DC receiving current Idc. Current increase control is performed by connecting a dummy load between the supply paths of the DC receiving current Idc.

  Specifically, the control unit 27 is configured to connect a dummy load having a relatively large load as the DC power receiving current Idc decreases. That is, in the example shown in FIG. 17, as the value of the DC receiving current Idc becomes smaller than the threshold current Ith (as the current range A11 → current range A12 → current range A13 is shifted), (load: small) The dummy load types are switched and connected in the order of (load: medium) → (load: large).

  In this way, in this modification, a dummy load of a type selected from a plurality of types of dummy loads having different load sizes is connected in accordance with the magnitude of the detected DC receiving current Idc. Therefore, finer current increase control can be performed.

  In the example shown in FIG. 17, three types of dummy loads having different loads are used. However, the present invention is not limited to this, and two or more types of dummy loads having different loads are used. You may do it.

[Modification 3]
(Constitution)
FIG. 18 is a block diagram and a circuit diagram illustrating a configuration example of a power feeding system (power feeding system 4A) according to Modification 3. A power feeding system 4A according to this modification includes a power feeding device 1 and an electronic device 2A. That is, in the power feeding system 4, the electronic device 2A is provided instead of the electronic device 2, and the other configurations are basically the same.

  As shown in FIG. 18, the electronic device 2 </ b> A corresponds to the electronic device 2 in which the current increase control unit 23 </ b> A is provided instead of the dummy load circuit 23 and the control unit 27 </ b> A is provided instead of the control unit 27. The other configurations are basically the same. The control unit 27A corresponds to the control unit 27 in which the above-described current increase control is not performed, and other functions are basically the same. Further, the current increase control unit 23A performs current increase control described below instead of the control unit 27, and corresponds to a specific example of “control unit” in the present disclosure.

  FIG. 19 is a block diagram illustrating a configuration example of the current increase control unit 23A, and FIG. 20 is a circuit diagram illustrating a configuration example of the current increase control unit 23A illustrated in FIG. 21A and 21B are circuit diagrams showing a detailed configuration example of the current increase control unit 23A shown in FIG. 20 together with a circuit configuration example of the current detection unit 22, respectively.

  As will be described later, the current increase control unit 23A is configured so that the DC received current Idc increases to be equal to or greater than the threshold current Ith (Idc ≧ Ith). In other words, the DC received current Idc is less than the threshold current Ith (Idc <Ith). This is a circuit (automatic load control unit) that actively performs current increase control. As illustrated in FIG. 19, the current increase control unit 23 </ b> A includes a reference voltage output unit 231, a comparator (comparator) 232, an integrator 233, and a transistor 234.

  Here, before describing these configurations in the current increase control unit 23A, a circuit configuration example of the current detection unit 22 in the present modification will be described with reference to FIGS. 20, 21A, and 21B. In this modification, the current detection unit 22 detects a current (DC reception current Idc) as a voltage (DC reception voltage Vdc), and includes, for example, a resistor 22R and an amplifier (amplifier) 22A. . The resistor 22R is inserted and arranged on the supply path (power supply line Lp) of the DC received current Idc. The wiring connected to one end side of the resistor 22R is connected to the positive (+) side input terminal of the amplifier 22A, and the wiring connected to the other end side of the resistor 22R is connected to the negative (−) side input terminal. Is connected. Further, the detected DC reception current Idc is output as the DC reception voltage Vdc from the output terminal of the amplifier 22A.

The reference voltage output unit 231 is a circuit that outputs a reference voltage Vref corresponding to the threshold current Ith. For example, as illustrated in FIG. 20, the reference voltage output unit 231 includes two resistors 231R1 and 231R2. An input voltage Vin1 described later is input to one end of the resistor 231R1, and the other end of the resistor 231R1 is connected to one end of the resistor 231R2 and a negative input terminal of the comparator 232 described later. The other end of the resistor 231R2 is grounded. With this configuration, the reference voltage output unit 231 divides the input voltage Vin1 according to the resistance ratio of the resistors 231R1 and 231R2, and outputs the divided voltage as the reference voltage Vref. Specifically, when the resistance values of the resistors 231R1 and 231R2 are R11 and R12, respectively, the reference voltage Vref is expressed by the following equation (1).
Vref = Vin1 × {R12 / (R11 + R12)} (1)

  Here, as this input voltage Vin1, for example, as shown in FIG. 21A, a predetermined fixed voltage Vcnst is used (Vin1 = Vcnst), and for example, as shown in FIG. 21B, a DC received voltage that is a variable voltage. And Vdc is used (Vin1 = Vdc).

  In the example of FIG. 21A, the reference voltage output unit 231 divides the fixed voltage Vcnst according to the resistance ratio described above, thereby generating a reference voltage Vref that is a constant voltage. On the other hand, in the example of FIG. 21B, the reference voltage output unit 231 divides the DC received voltage Vdc in accordance with the above-described resistance ratio, so that it is a variable voltage that changes in conjunction with the change in the DC received voltage Vdc. A certain reference voltage Vref is generated.

  As shown in FIG. 19, the comparator 232 compares the magnitudes of the voltages (potentials) between the DC received voltage Vdc corresponding to the DC received current Idc and the reference voltage Vref corresponding to the threshold current Ith. Is a circuit that outputs an output signal (output voltage Vout). In this comparator 232, as shown in FIGS. 19 to 21B, the DC power reception voltage Vdc is input to the positive input terminal, the reference voltage Vref is input to the negative input terminal, and the output voltage Vout is output from the output terminal. It has come to be.

  The integrator 233 generates and outputs a control signal CTL3 for the transistor 234 based on the output voltage Vout supplied from the comparator 232, thereby performing a current increase control (active LPF (Low Pass Filter), PI (Proportional Integral) control circuit). Specifically, the integrator 233 integrates the output voltage Vout from the comparator 232 so as to generate such a control signal CTL3.

  The integrator 233 includes, for example, four resistors 233R1, 233R2, 233R3, 233R4, one capacitor 233C, and one amplifier 233A as shown in FIGS. 20, 21A, and 21B. . The input voltage Vin3 is input to one end of the resistor 233R1, the other end of the resistor 233R1 is connected to one end of the resistor 233R2 and the positive input terminal of the amplifier 233A, and the other end of the resistor 233R2 is grounded. . Also, one end of the resistor 233R3 is connected to the output terminal of the comparator 232, and the other end of the resistor 233R3 is connected to the negative side input terminal of the amplifier 233A and one end of each of the capacitor 233C and the resistor 233R4. Yes. The other ends of the capacitor 233C and the resistor 233R4 are connected to the output terminal of the amplifier 233A and the gate of a transistor 234 described later.

  The transistor 234 operates according to the control by the control signal CTL3 supplied from the integrator 233, and is composed of a MOS transistor in this example. However, the transistor 234 may be, for example, a bipolar transistor. As shown in FIGS. 19 to 21B, the control signal CTL3 is input to the gate of the transistor 234, one of the source and the drain is connected to the supply path (power supply line Lp) of the DC received current Idc, and the other Is grounded. With this configuration, the transistor 234 allows a current to flow between the power supply line Lp and the ground in accordance with the control of the gate voltage by the control signal CTL3.

(Action / Effect)
In the power feeding system 4A of the present modification, the following operation (current increase control) is performed in the current increase control unit 23A.

  First, the comparator 233 in the current increase control unit 23A determines whether the DC received voltage Vdc at the time of the light load is less than the reference voltage Vref based on the output signal (output voltage Vout) from the comparator 232. (Vdc <Vref is satisfied or not) is determined. In other words, the integrator 233 determines whether or not the DC received current Idc at a light load is less than the threshold current Ith (whether or not Idc <Ith is satisfied).

  Here, if it is determined that Vdc ≧ Vref (Idc ≧ Ith), there is a possibility that the received voltage may be uncontrollable due to a light load as described above, or that the received voltage may become an overvoltage. It can be said that there is no. Therefore, in this case, the current increase control described below is not performed in the current increase control unit 23A. That is, in this case, for example, as shown in FIG. 22A, the transistor 234 is set to the OFF state in accordance with the control signal CT3 output from the integrator 233, and no current flows through the transistor 234.

  On the other hand, if it is determined that Vdc <Vref (Idc <Ith), there is a possibility that the received voltage may be uncontrollable due to a light load as described above, or that the received voltage may become an overvoltage. It can be said that there is. Therefore, in this case, the following current increase control is performed in the current increase control unit 23A. Specifically, in such a case, for example, as shown in FIG. 22B, the integrator 233 sets the transistor 234 to the on state by the control signal CT3, and sets the transistor 234 to the supply path (power) of the DC receiving current Idc. Connected to the supply line Lp). As a result, as shown in FIG. 22B, the current Ic flows through the transistor 234, and the direct current receiving current Idc increases. In this way, the current increase control is performed so that the DC received current Idc increases to the threshold current Ith or more (Idc ≧ Ith).

  Here, FIG. 23 and FIG. 24 show examples of actual measurement results according to the modified example 3, both when the current increase control unit 23 is present (example) and when it is not present (comparative example). Specifically, FIG. 23 shows an example of an actual measurement result showing the relationship between the DC receiving current Idc and the DC receiving voltage Vdc, and FIG. 24 shows an example of an actual measurement result showing the time change of the AC receiving voltage Vac. . In addition, the result similar to the case of simulation was obtained for each of these measurement result examples.

  It can be seen from FIG. 23 that by providing the current increase control unit 23A, a sudden increase in the DC received voltage Vdc when the DC received current Idc is small is avoided. Further, FIG. 24 shows that by providing the current increase control unit 23A, ringing at the AC received voltage Vac caused by harmonics is suppressed, and the voltage rise is suppressed.

  FIG. 25 shows a reference voltage Vref and parameters (DC received voltage Vdc, threshold current Ith) in the case of the circuit configuration shown in FIG. 21B (configuration using a DC received voltage Vdc that is a variable voltage as the input voltage Vin1). , Load resistance value), an example of an actual measurement result showing the relationship. According to FIG. 25, even when the DC power reception voltage Vdc changes, in the case of this circuit configuration, the reference voltage Vref (threshold current Ith) also changes accordingly as described above. It can be seen that the value of is kept constant. Specifically, in this case, the reference voltage Vref (threshold current Ith) increases as the DC power reception voltage Vdc increases, and the load resistance value increases as more current (DC power reception current Idc) flows. Is kept constant.

  As described above, in this modification, in the current increase control unit 23A, when the DC received current Idc at the time of light load is less than the threshold current Ith, the DC received current Idc is increased to be equal to or greater than the threshold current Ith. Perform current increase control. Thereby, even at such a light load, it is possible to easily control the power reception voltage (DC power reception voltage Vdc, etc.) in the electronic device 2A. Specifically, for example, as described in FIG. 8, it is possible to avoid the possibility that the received voltage becomes uncontrollable due to a light load or that the received voltage becomes an overvoltage. Therefore, as in the above-described embodiment, appropriate control can be performed when power is supplied using a magnetic field.

  In particular, in this modification, autonomous (active) current increase control is possible and stepwise, unlike the case of current increase control using the dummy load circuit 23 described in the above embodiment. Continuous current increase control is possible instead of (non-continuous).

  Further, for example, as shown in FIG. 21B, the reference voltage Vref, which is a variable voltage that changes in conjunction with the change in the DC reception voltage Vdc, is generated by dividing the DC reception voltage Vdc. In some cases, for example, the following effects can be obtained. That is, for example, when the voltage fluctuation of the DC receiving voltage Vdc is large, it is more effective to keep the load resistance value constant using such a circuit configuration than to keep the DC receiving current Idc constant. Can be bigger.

[Modification 4]
(Constitution)
FIG. 26 illustrates a circuit configuration example of a current increase control unit (current increase control unit 23B) according to Modification 4. The current increase control unit 23B of the present modification includes a reference voltage output unit 231B instead of the reference voltage output unit 231 in the current increase control unit 23 (configuration of FIG. 21B) described in the modification 3, and a control unit 27A. Corresponds to the control of the operation of the reference voltage output unit 231B, and the other configurations are basically the same.

  The reference voltage output unit 231B is configured to be able to change the voltage dividing ratio when the DC received voltage Vdc is divided in the reference voltage output unit 231 shown in FIG. 21B. Specifically, in this reference voltage output unit 231B, instead of the resistor 231R1 shown in FIG. 21B, two resistors 231R1a and 231R1b connected in parallel to each other are provided, and one switching composed of a MOS transistor or the like is provided. The element SW31 is connected in series with the resistor 231R1b. Similarly, instead of the resistor 231R2 shown in FIG. 21B, two resistors 231R2a and 231R2b connected in parallel to each other are provided, and one switching element SW32 made of a MOS transistor or the like is connected to the resistor 231R2b. They are connected in series. Each of the switching elements SW31 and SW32 is individually controlled in accordance with the control signals CTL31 and CTL32 supplied from the control unit 27A (see FIG. 26). (See dashed arrow).

  In the reference voltage output unit 231B, the on / off states of the switching elements SW31 and SW32 are individually controlled in this way, and as described above, the voltage division ratio (resistance ratio) when dividing the DC received voltage Vdc. Changes. Thereby, in the current increase control unit 23B of the present modification, the value of the reference voltage Vref can be changed according to the control by the control unit 27A, and for example, the following effects can be obtained in addition to the effects in the third modification. Become.

  That is, the current increase control unit 23A described in the third modification basically does not require dynamic control by the control unit 27A, and has a great advantage that a stand-alone operation is possible. On the other hand, when performing non-contact power feeding, there are often a plurality of phases such as an initial operation phase, a communication phase, and a power feeding phase. Further, since it is conceivable to change the topology according to the power, it is also assumed that the current value to be controlled and the load resistance value are changed for each of such a plurality of phases. Therefore, by using the current increase control unit 23B of the present modification, the load control is actively performed with the initial parameters without the need for dynamic control by the control unit 27A, and the control value (current value or Load resistance value) can be changed.

  Further, by controlling so that the load resistance value does not exceed a certain value, it is possible to avoid the possibility that the DC received voltage Vdc becomes an overvoltage, as in the case of controlling the current value.

  In this modification, the voltage dividing ratio is changed using the on / off states of the switching elements SW31 and SW32. However, the present invention is not limited to this. For example, the voltage dividing ratio may be changed by making each of the resistors 231R1 and 231R2 shown in FIG. 21B variable resistors.

<Other variations>
As described above, the technology of the present disclosure has been described with reference to the embodiment and the modifications. However, the technology is not limited to the embodiment and the like, and various modifications can be made.

  For example, although various embodiments (power transmission coil, power reception coil) have been described in the above-described embodiments, various configurations (shapes) of these coils can be used. That is, for example, spiral shape and loop shape, bar shape using magnetic material, α winding shape that spiral coils are folded in two layers, further multilayer spiral shape, helical with winding wound in the thickness direction Each coil can be configured depending on the shape and the like. Moreover, each coil may be not only a wound coil made of a conductive wire, but also a conductive pattern coil made of a printed board, a flexible printed board, or the like.

  Moreover, in the said embodiment etc., although the electronic device was mentioned and demonstrated as an example of electric power feeding object apparatus, it is not restricted to this, It is electric power feeding object apparatuses (for example, vehicles, such as an electric vehicle) other than an electronic device, Also good.

  Furthermore, in the above-described embodiment and the like, the respective components of the power feeding device and the electronic device have been specifically described, but it is not necessary to include all the components, and other components may be further included. Good. For example, a communication function, some control function, a display function, a function to authenticate a secondary device, a function to detect mixing of a dissimilar metal, or the like may be installed in the power supply apparatus or the electronic device. In addition, the configuration of the current increasing unit (dummy load circuit) and the current increasing control unit, and the method of increasing the current are not limited to those described in the above embodiment, and other configurations and methods may be used. . Specifically, for example, the number of dummy loads in the dummy load circuit is not limited to the number (two) described in the above-described embodiment, and may be one or three or more. Further, for example, instead of performing PI control in the current increase control unit, PID (Proportional Integral Derivative) control may be performed. Furthermore, in the above-described embodiment and the like, as an example of “light load” that is an object of current increase control, a standby power supply period (first period) and a charging operation period for a secondary battery based on the main power supply (first period) The second period) has been described as an example, but the present invention is not limited to this. For example, only one of the first period and the second period may be “light load”, and that period may be the target of current increase control.

  In addition, in the above-described embodiment and the like, the case where the current detection unit 22 detects the received current (DC received current Idc) after rectification by the rectifier circuit 21 has been described as an example, but is not limited thereto. That is, for example, a received current (AC received current Iac) before rectification by the rectifier circuit 21 may be detected and used for current increase control. Or you may make it detect the electric current (load current) which flows into the battery 25 as a receiving electric current. However, since the DC power reception current Idc is easier to detect than the AC power reception current Iac, it can be said that it is desirable to detect the DC power reception current Idc. Note that the positions of the dummy load circuit 23 and the current increase control units 23A and 23B are not limited to the rear stage side of the rectifier circuit 21 as in the above-described embodiment, but are disposed, for example, on the front stage side of the rectifier circuit 21. You may do it.

  In the above-described embodiment and the like, the case where only one electronic device is provided in the power supply system has been mainly described as an example. However, the present invention is not limited to this case, and a plurality of (2 Two or more electronic devices may be provided.

  Further, in the above-described embodiment and the like, a charging tray for a small electronic device (CE device) such as a cellular phone has been described as an example of a power feeding device. However, as a power feeding device, such a household charging tray is used. It is not limited to, but can be applied as a charger for various electronic devices. Further, it is not necessarily a tray, and may be a stand for an electronic device such as a so-called cradle.

  In addition, the effect described in this specification is an illustration to the last, and is not limited, Moreover, there may exist another effect.

In addition, this technique can also take the following structures.
(1)
A power receiving unit that receives power fed from a power feeding device using a magnetic field;
A control unit and
When the received current supplied from the power receiving unit is less than a predetermined threshold current at light load, the control unit performs current increase control so that the received current increases to be equal to or higher than the threshold current. machine.
(2)
A current increasing unit having one or more dummy loads;
The electronic device according to (1), wherein the control unit performs the current increase control using at least one of the dummy loads.
(3)
The controller is
When the received current is less than the threshold current,
The electronic apparatus according to (2), wherein the current increase control is performed by connecting at least one of the dummy loads between the supply current supply paths and controlling the current to flow through the dummy load. .
(4)
The said control part isolate | separates the said dummy load from between the said supply path | routes, when this load is set to a connection state, The electronic device as described in said (3).
(5)
The electronic device according to (3), wherein the control unit disconnects the dummy load from between the supply paths when the power receiving current is equal to or greater than the threshold current after the load is set in a connected state. .
(6)
The current increasing unit has a plurality of types of the dummy loads having different load sizes,
The controller is
When the received current is less than the threshold current,
The electronic device according to any one of (3) to (5), wherein a dummy load of a type selected from the plurality of types of dummy loads according to the magnitude of the received current is connected between the supply paths. .
(7)
The controller is
The electronic device according to (6), wherein a dummy load having a relatively large load is connected between the supply paths as the power receiving current decreases.
(8)
If the received current is still less than the threshold current after at least one of the dummy loads is connected between the supply paths,
The electronic device according to any one of (3) to (7), wherein the control unit additionally connects the dummy load between the supply paths, or switches the dummy load to one having a larger load. .
(9)
The controller is
A comparator that compares the received voltage corresponding to the received current with the reference voltage corresponding to the threshold current;
An integrator for inputting an output signal from the comparator;
The electronic device according to (1), further including a transistor that operates according to control by the integrator.
(10)
The integrator is
When it is determined that the received voltage is less than the reference voltage based on the output signal,
The electronic device according to (9), wherein the current increase control is performed by connecting the transistor between the power receiving current supply paths and controlling the current to flow through the transistor.
(11)
The electronic device according to (9) or (10), wherein the reference voltage is a constant voltage.
(12)
The electronic device according to (9) or (10), wherein the reference voltage is a variable voltage that changes in conjunction with a change in the received voltage.
(13)
The reference voltage is generated by dividing a predetermined fixed voltage or the receiving voltage;
The electronic device according to any one of (9) to (12), wherein the reference voltage value can be changed by changing a voltage dividing ratio when the voltage is divided.
(14)
At the time of the light load,
A first period during which a preliminary power supply with lower power than the main power supply is performed from the power supply device;
After the first period, at least one of a second period in which a secondary battery as a main load is set in a connected state and a charging operation for the secondary battery based on the main power supply is performed The electronic device according to any one of 1) to (13).
(15)
While the charging operation is performed in the second period,
The electronic device according to (14), wherein whether or not the received current is less than the threshold current is periodically determined.
(16)
The controller is
After the received current increases to the threshold current or more in the first period,
The electronic device according to (14) or (15), wherein the power supply start request is notified to the power supply device.
(17)
The electronic device according to any one of (1) to (16), wherein the threshold current value is configured to be changeable.
(18)
A current detection unit for detecting the received current;
The electronic device according to any one of (1) to (17), wherein the control unit performs the current increase control using a received current detected by the current detection unit.
(19)
A rectifier circuit for rectifying the received current;
The electronic device according to (18), wherein the current detection unit detects a received current after rectification by the rectifier circuit.
(20)
One or more electronic devices;
A power supply device that supplies power using a magnetic field to the electronic device,
The electronic device is
A power receiving unit that receives power fed from the power feeding device;
A control unit, and
When the received current supplied from the power receiving unit is less than a predetermined threshold current at light load, the control unit performs current increase control so that the received current increases to be equal to or higher than the threshold current. system.

  DESCRIPTION OF SYMBOLS 1 ... Power feeding apparatus, 10 ... Power transmission part, 11 ... AC signal generation circuit, 12 ... Communication part, 13 ... Control part, 2, 2A ... Electronic device, 20 ... Power receiving part, 21 ... Rectifier circuit, 22 ... Current detection part, DESCRIPTION OF SYMBOLS 23 ... Dummy load circuit, 23A, 23B ... Current increase control part, 231, 231B ... Reference voltage output part, 232 ... Comparator, 233 ... Integrator, 234 ... Transistor, 24 ... Charging part, 25 ... Battery, 26 ... Communication , 27, 27A ... control unit, 28 ... memory unit, 4, 4A ... power supply system, 9 ... external power supply, S1 ... power transmission surface, L1 ... power transmission coil, L2 ... power reception coil, C1, C2s, C2p ... capacitor, SW1 , SW2, SW31, SW32 ... switching element, Ra, Rb ... dummy load (dummy resistor), Sdc ... DC signal, Sac ... AC signal, CTL1, CTL2, CTL3, CTL31, CTL 32 ... Control signal, Lp ... Power supply line, Vac ... AC receiving voltage, Vdc ... DC receiving voltage, Vref ... Reference voltage, Vin1, Vin3 ... Input voltage, Vout ... Output voltage, Vcnst ... Fixed voltage, Iac ... AC receiving current , Idc ... DC receiving current, Ith ... threshold current, Ia, Ib, Ic ... current, A1, A11, A12, A13, A2 ... current range.

Claims (12)

A power receiving unit for receiving non-contact power supplied from the power supply device;
A control unit and
The controller is
In the period during which the preliminary power supply is performed with lower power than the main power supply from the power supply device ,
As receiving the current supplied from the power receiving unit becomes a predetermined current value or more, an electronic device that performs current increase control. The control unit performs the current increase control using at least one of one or a plurality of loads.
The electronic device according to claim 1. One or more electronic devices;
A power supply device that performs non-contact power supply to the electronic device,
The electronic device is
A power receiving unit that receives power that is contactlessly fed from the power feeding device;
A control unit, and
The controller is
In the period during which the preliminary power supply is performed with lower power than the main power supply from the power supply device ,
As receiving the current supplied from the power receiving unit becomes a predetermined current value or more, power supply system for the current increase control. While performing non-contact power feeding from a power feeding device to one or a plurality of power feeding target devices,
In the period during which preliminary power supply is performed at a lower power than the main power supply from the power supply device to the power supply target device,
Current increase control is performed in the power supply target device so that the received current obtained by the non-contact power supply becomes equal to or greater than a predetermined current value.
Non-contact power supply method. The current increase control is performed using at least one of one or a plurality of loads.
The non-contact electric power feeding method according to claim 4. The current increase control is performed by connecting at least one of the loads between the supply current supply paths and controlling the current to flow through the load.
The contactless power feeding method according to claim 5. A type of load selected from a plurality of types of loads having different load values depending on the magnitude of the received current is connected between the supply paths.
The non-contact power feeding method according to claim 6. As the power receiving current decreases, a load having a relatively large load value is connected between the supply paths.
The contactless power feeding method according to claim 7. A first period during which the preliminary power supply is performed;
After the first period, a second period in which a secondary battery as a main load is set in a connected state and a charging operation to the secondary battery based on the main power supply is performed.
Only in the first period,
Perform the current increase control
The non-contact power feeding method according to any one of claims 4 to 8. Before the incoming current is detected,
Starting the preliminary power supply from the power supply device to the power supply target device,
Using the received power obtained by the preliminary power supply, activate the power supply target device,
The received power at the time of the main power supply is determined using communication between the power supply device and the power supply target device.
The non-contact electric power feeding method according to any one of claims 4 to 9. Using communication between the power supply apparatus and the power supply target device, mutual device authentication or power supply efficiency control is performed.
The non-contact electric power feeding method according to any one of claims 4 to 10. The power supply target device is an electronic device or a vehicle.
The non-contact electric power feeding method according to any one of claims 4 to 11.

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