JP6365787B2 - Power receiving device - Google Patents

Description

  The present invention relates to a power receiving apparatus that receives power from a power transmitting apparatus and supplies a power supply voltage to a load circuit, and more particularly to a power receiving apparatus in which fluctuations in the received voltage are severe.

  Patent Document 1 discloses a wireless mouse non-contact power feeding system that feeds power from a mouse pad in a non-contact manner.

  In a wireless power receiving mouse that receives and operates when magnetic flux is generated from the power transmission coil provided in the mouse pad and that magnetic flux is linked to the power receiving coil, the power is received when the mouse is temporarily removed from a position where it cannot receive power from the mouse pad. The power decreases and the power supply voltage supplied to the mouse decreases. When the power supply voltage falls below a predetermined voltage, the load circuit including the control IC provided in the mouse is reset, so that the operation of the mouse becomes discontinuous and the operability is greatly reduced.

  Therefore, in the wireless mouse non-contact power feeding system disclosed in Patent Document 1, power feeding selection means for selecting one power feeding coil corresponding to the position of the mouse from a plurality of coils provided on the mouse pad, and a power receiving coil. And a circuit for charging an electric double layer capacitor (hereinafter referred to as “EDLC”) with the received electric power. With this configuration, the EDLC is charged when receiving power from the mouse pad, and power is supplied from the EDLC to the load circuit when power cannot be received from the mouse pad.

JP 2009-271446 A

  A power storage means such as EDLC can maintain the operation of the mouse upon momentary or short-time power interruption. However, when the EDLC is installed, if the power charged to the EDLC is larger than the received power received from the mouse pad, the voltage supplied to the load circuit rises slowly, resulting in a startup delay that takes time to start the mouse. There is. Further, when the received power temporarily decreases, power is supplied from the EDLC to the load circuit. However, when the amount of electricity stored in the EDLC decreases and the voltage supplied to the load decreases, the mouse operation stops. If the received power increases before the voltage supplied to the load becomes zero and the voltage supplied to the load increases, a malfunction that cannot be resumed while the mouse operation is stopped may occur.

  The above-described event is not limited to the wireless mouse non-contact power feeding system, and is common to the power feeding system in which the power receiving voltage can be unstable in the power feeding system from the power transmitting apparatus to the power receiving apparatus.

  An object of the present invention is to provide a power receiving device that prevents a start-up delay or malfunction of a load circuit due to fluctuations in the received voltage.

(1) A wireless power receiving system of the present invention includes a power receiving unit that receives power from a power transmission device, and a power storage unit that is provided between the power receiving unit and a load circuit and charges an output voltage of the power receiving unit. The power receiving device includes a cutoff circuit that shuts off the power storage unit from the load circuit when an input voltage of the load circuit falls below a first threshold value.

  According to the above configuration, when the input voltage (output voltage of the power receiving unit) of the load circuit gradually decreases and falls below the first threshold value, the power storage unit is disconnected from the load circuit, so that the load from the power storage unit is reduced. Power supply voltage supply to the circuit is cut off. As a result, the load circuit is prevented from malfunctioning due to continued unstable power supply voltage.

(2) It is preferable that the said interruption | blocking circuit is provided with the 1st switch element connected in series with the said electrical storage part. Thereby, there is no useless charge discharge of the power storage unit, and power storage can be started from the voltage when the power storage unit is connected thereafter. That is, since the voltage of the power storage unit can be used effectively immediately after connection, the time required for activation can be shortened.

(3) In the above (1) or (2), when the input voltage exceeds a second threshold value that is higher than the first threshold value, a quick charging circuit that increases a current supplied to the power storage unit It is preferable to provide. As a result, even when rapid charging of the power storage unit is started, the power supply voltage can be supplied to the load circuit quickly, and the voltage of the power storage unit can be quickly increased by rapid charging, so that it is possible to cope with a decrease in received power immediately after. .

(4) In the above (2), provided with a quick charging circuit for increasing a current supplied to the power storage unit when the input voltage exceeds a second threshold value higher than the first threshold value, The quick charging circuit preferably includes a second switch element connected in parallel to the resistance element. As a result, quick charging can be performed only by turning on the second switch. That is, it can be configured with a simple circuit.

(5) In the above (4), the voltage dividing circuit for detecting the input voltage, and the first switch element and the second switch element are turned on when the input voltage exceeds a second threshold value. A switching circuit; and a voltage dividing ratio switching circuit that switches the voltage dividing ratio of the voltage dividing circuit when the switch circuit is turned on and turns off the switch circuit when the input voltage falls below the first threshold value. . This makes it possible to switch between supply / cutoff of the power supply voltage from the power storage unit to the load circuit and execution / stop of quick charging at two thresholds of the input voltage while using a single circuit for detecting the input voltage. Can be switched.

(6) In the above (4) or (5), it is preferable that a resistance element connected in parallel to the second switch element is provided. Thereby, the resistance element constitutes a supplementary charging current path. When the electrical storage part 30 is comprised with a chemical secondary battery, when charging from an overdischarged state, it is preferable to charge from a micro charge current.

(7) In any one of (1) to (6), the power storage unit preferably includes an electric double layer capacitor. Generally, since an electric double layer capacitor has a lower internal resistance than a chemical secondary battery, the charging time can be shortened, and the power storage unit is quickly charged even under intermittent power receiving conditions. In addition, since the electric double layer capacitor has a higher volumetric energy density and weight energy density than a chemical secondary battery, it can be applied to a small and lightweight power receiving device.

(8) In any one of the above (1) to (7), for example, the power reception unit wirelessly receives power from the power transmission device. This effectively prevents a start-up delay or malfunction of the load circuit due to fluctuations in received power.

(9) In the above (8), the load circuit may be a mouse circuit, for example, and the power reception unit may receive power from the power transmission device provided in a mouse pad.

  According to the present invention, a power receiving device is configured in which a start delay or malfunction of the load circuit due to fluctuations in the received voltage is prevented.

FIG. 1A is a block diagram of a wireless power feeding system including a wireless power receiving apparatus 100A and a power transmitting apparatus 200 according to the first embodiment. FIG. 1B is a block diagram of a wireless power feeding system including the wireless power receiving apparatus 100B and the power transmitting apparatus 200 according to the first embodiment. FIG. 2 is a circuit diagram of the power receiving unit 10. FIG. 3 is a flowchart showing the operation of the cutoff circuit 40 and the quick charging circuit 50 in accordance with the input voltage of the load circuit 20. FIG. 4 is a table showing operations of the cutoff circuit 40 and the quick charging circuit 50 in accordance with the input voltage of the load circuit 20. FIG. 5 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving apparatus according to the second embodiment. FIG. 6 is a waveform diagram of the input voltage Vin of the load circuit 20 and the charging voltage (both ends voltage) Vc of the power storage unit 30. FIG. 7 is a circuit diagram of a cut-off circuit and a quick charge circuit of the wireless power receiving apparatus according to the third embodiment. FIG. 8 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving apparatus according to the fourth embodiment. FIG. 9 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving apparatus according to the fifth embodiment. FIG. 10 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving apparatus according to the sixth embodiment. FIG. 11 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving apparatus according to the seventh embodiment. FIG. 12 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving device according to the eighth embodiment. FIGS. 13A and 13B are diagrams illustrating the voltage division ratio switching of the voltage division ratio switching circuit 61 according to the state of the transistor Q1 included in the wireless power receiving device according to the eighth embodiment. FIG. 14 is a flowchart showing the state transition of the transistor Q1, FETs Q2, Q6 in accordance with the input voltage Vin of the load circuit. FIG. 15 is a diagram illustrating state transition of connection / cutoff of power storage unit 30 according to input voltage Vin of the load circuit. FIG. 16 is a waveform diagram of the input voltage Vin of the load circuit and the charging voltage (both ends voltage) Vc of the power storage unit 30. FIG. 17 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving apparatus according to the ninth embodiment. FIG. 18 is a block diagram of a power supply system according to the tenth embodiment.

  Hereinafter, several specific examples will be given with reference to the drawings to show a plurality of modes for carrying out the present invention. In each figure, the same reference numerals are assigned to the same portions. In consideration of ease of explanation or understanding of the main points, the embodiments are shown separately for convenience, but the components shown in different embodiments can be partially replaced or combined. In the second and subsequent embodiments, description of matters common to the first embodiment is omitted, and only different points will be described. In particular, the same operation effect by the same configuration will not be sequentially described for each embodiment.

<< First Embodiment >>
FIG. 1A is a block diagram of a wireless power feeding system including a wireless power receiving apparatus 100A and a power transmitting apparatus 200 according to the first embodiment. FIG. 1B is a block diagram of a wireless power feeding system including the wireless power receiving apparatus 100B and the power transmitting apparatus 200 according to the first embodiment. The power transmission device 200 is, for example, a mouse pad, and the wireless power receiving device is a wireless mouse that receives power wirelessly from the mouse pad.

  A wireless power receiving device 100A illustrated in FIG. 1 includes a power receiving unit 10 that wirelessly receives power from the power transmitting device 200, and a load circuit 20 that consumes the power received by the power receiving unit 10. A power storage unit 30 that charges the output voltage of the power receiving unit 10 is provided between the power receiving unit 10 and the load circuit 20. Further, a cutoff circuit 40 is provided that shuts off the power storage unit 30 from the load circuit when the input voltage of the load circuit 20 falls below the first threshold value.

  The power receiving unit 10 wirelessly receives power by performing magnetic field coupling, electric field coupling, or electromagnetic field coupling with the power transmission unit 211 of the power transmission device 200. The power receiving unit 10 includes a resonance unit 11, a rectifying / smoothing circuit 12, and a voltage stabilizing circuit 13.

  The cutoff circuit 40 includes a switch SW1 connected in series to the power storage unit 30, and a voltage detection circuit 41 that controls the switch SW1 by comparing the input voltage of the load circuit 20 with a first threshold value.

  The quick charging circuit 50 includes a resistor Rc connected in series to the power storage unit 30, a switch SW2 connected in parallel to the resistor Rc, and a voltage detection for controlling the switch SW2 by comparing the input voltage of the load circuit 20 with a second threshold value. A circuit 51.

  The wireless power receiving apparatus 100B illustrated in FIG. 1B is different from the wireless power receiving apparatus 100A illustrated in FIG. 1A in the configuration of the cutoff circuit 40 and the configuration of the quick charging circuit 50. In the wireless power receiving apparatus 100B, the cutoff circuit 40, the power storage unit 30, and the quick charging circuit 50 are connected in series in this order from the line of the input voltage (output voltage of the power receiving unit 10) Vin of the load circuit to the reference potential (ground). Has been. Other configurations are the same as those of the wireless power receiving apparatus 100A.

  Both the wireless power receiving apparatus 100A shown in FIG. 1A and the wireless power receiving apparatus 100B shown in FIG. 1B operate in the same manner.

  FIG. 2 is a circuit diagram of the power receiving unit 10. The resonance unit 11 includes power receiving coils Ls1, Ls2, and Ls3 and capacitors Crs1, Crs2, and Crs3. The receiving coil Ls1 and the capacitor Crs1 constitute a first resonance circuit, the receiving coil Ls2 and the capacitor Crs2 constitute a second resonance circuit, and the receiving coil Ls3 and the capacitor Crs3 constitute a third resonance circuit.

  The rectifying / smoothing circuit 12 includes a diode Dr and a capacitor Co1, and rectifies and smoothes the voltage of the resonance circuit.

  The voltage stabilization circuit 13 includes a positive temperature coefficient thermistor PTC, a Zener diode ZDp, a diode Dp, and a DC-DC converter CNV. The positive characteristic thermistor PTC limits the inflow current at the time of overcurrent or overheat, and the Zener diode ZDp determines the upper limit voltage of the received voltage. The diode Dp serves as a path for the return current flowing in the input part of the DC-DC converter CNV.

  The DC-DC converter CNV inputs an unstable DC voltage, and outputs a stabilized DC voltage by feedback control based on a comparison between the output voltage and a reference voltage.

  FIG. 3 is a flowchart showing the operation of the cutoff circuit 40 and the quick charging circuit 50 in accordance with the input voltage of the load circuit 20. FIG. 4 is a table showing the operation of the cutoff circuit 40 and the quick charging circuit 50 in accordance with the input voltage of the load circuit 20.

  An example of the operation of the cutoff circuit 40 and the quick charging circuit 50 according to the level relationship between the input voltage (output voltage of the power receiving unit 10) Vin of the load circuit and the first threshold value Vth1 and the second threshold value Vth2 is as follows. is there.

[ON condition of SW1]
Vin ≧ Vth1 (3.9V)
[ON condition of SW2]
Vin ≧ Vth2 (4.0V)
For example, the rated voltage of Vin is 5.0V, Vth1 = 3.9V, and Vth2 = 4.0V.

  When power reception is started, the input voltage Vin of the load circuit 20 rises rapidly. When Vin reaches the operable voltage of the load circuit 20, the load circuit 20 starts to operate. When Vin exceeds 4.0V, both the switches SW1 and SW2 are turned on. As a result, the power storage unit 30 starts to be quickly charged. Since Vin (= 4.0 V) at this time is a sufficient voltage for the load circuit, the increase in Vin becomes slow or the voltage Vin temporarily decreases when the charging current starts to flow to the power storage unit 30. This prevents the load circuit from malfunctioning.

  Thereafter, when the received power decreases or stops, the power storage unit 30 starts discharging, and the charging voltage of the power storage unit 30 maintains the input voltage Vin of the load circuit 20. Thereafter, the voltage of the power storage unit 30 gradually decreases. When the input voltage Vin of the load circuit 20 becomes less than 3.9 V, the switch SW1 is turned off and the power storage unit 30 is cut off (disconnected). As a result, Vin decreases rapidly. Therefore, insufficient voltage Vin is not continuously applied to the load circuit, and malfunction of the load circuit is prevented. Further, when Vin increases due to the subsequent start of power reception, the power-on reset is activated and the load circuit starts normally. Further, when the switch SW1 is turned off and the power storage unit 30 is disconnected, there is no useless charge discharge of the power storage unit 30, and when the power storage unit is connected thereafter, power storage can be started from that voltage. That is, the voltage of the power storage unit 30 can be used effectively immediately after connection.

  2 shows an example in which the resonance unit 11 includes three sets of resonance circuits. However, the present invention can be similarly applied to a configuration in which the resonance unit includes one set of resonance circuits, and provides the same effects. Four or more sets may be provided. FIG. 2 shows an example in which the rectifying / smoothing circuit 12 includes a diode (Dr1, Dr2, Dr3) for each resonance circuit, but the same applies to a configuration in which the rectifying / smoothing circuit 12 includes one rectifying circuit. And has the same effect. For example, in FIG. 2, the resonance unit may be configured by the power receiving coil Ls1 and the capacitor Crs1, and the rectifying and smoothing circuit 12 may be configured by the diode Dr1 and the capacitor Co1.

  2 shows an example in which the voltage stabilizing circuit 13 includes the positive temperature coefficient thermistor PTC, the Zener diode ZDp, and the diode Dp. However, these are not essential, and either or all of them may be omitted. .

  In this embodiment, a mouse is given as an example of a power receiving device whose position frequently moves. However, the present invention can be similarly applied to a toy, a controller of a game machine, or the like that receives power wirelessly from a power transmitting device. There is an effect.

<< Second Embodiment >>
2nd Embodiment shows the example of the specific circuit of the interruption | blocking circuit 40 and the quick charge circuit 50 among the circuits shown to FIG. 1A and FIG. 1B in 1st Embodiment.

  FIG. 5 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving apparatus according to the second embodiment. In FIG. 5, the load circuit 20 is represented by a resistor Ro. The power storage unit 30 is formed by connecting two sets of parallel circuits of EDLC and resistors in series.

  The resistors R11 and R12 constitute a voltage detection circuit 41. The resistors R31 and R32 constitute a voltage detection circuit 51. The transistor Q1, the resistor R2, and the FET Q2 constitute a switch SW1. The transistor Q3 and the resistor R33 constitute a switch SW2. FIG. 5 also shows the body diode and parasitic capacitance of the FET Q2.

  A diode Dc is connected in parallel to the resistor Rc. The diode Dc forms a discharge current path of the power storage unit 30, and the resistor Rc forms a supplementary charging current path. When the power storage unit 30 is composed of a chemical secondary battery, it is desirable to charge from a small charge current when charging the power storage unit 30 from an overdischarged state. By connecting the auxiliary charging current path by the resistor Rc in parallel with the path through which the quick charging current flows, the power storage unit 30 can be auxiliary charged in a period other than the quick charging.

  The operation of the circuit shown in FIG. 5 is as follows.

  When Vin becomes equal to or higher than the first threshold voltage Vth1 (3.9V), the base-emitter current of the transistor Q1 flows, Q1 is turned ON, and thereby the current flows through the path of the body diode of Q1 → R2 → FETQ2. , The gate-source voltage of Q2 is increased and Q2 is turned on.

  When Vin becomes the second threshold voltage Vth2 (4.0 V) or higher, the base-emitter current of the transistor Q3 flows, and Q3 is turned on. When Q3 is turned on, a rapid charging current flows through a path of DC-DC converter CNV → Q3 → R33 → 30 → Q2.

  When the power storage unit 30 is discharged, a discharge current flows through a route of 30 → Dc → Ro → Q2 → 30.

  When Vin becomes less than the first threshold voltage Vth1 (3.9 V), Q2 is turned OFF, the voltage of the power storage unit 30 is cut off, and Vin rapidly decreases. Further, the electric charge of the power storage unit 30 is retained.

  FIG. 6 is a waveform diagram of the input voltage Vin of the load circuit 20 and the charging voltage (both ends voltage) Vc of the power storage unit 30. When power reception starts at time t1, the input voltage Vin of the load circuit 20 rises rapidly, and when Vin exceeds 4.0V, both Q2 and Q3 are in the ON state. When both Q2 and Q3 are ON, power storage unit 30 is rapidly charged. When Vin reaches the operable voltage of the load circuit 20, the load circuit 20 starts to operate.

  After time t1, the charging voltage Vc of the power storage unit 30 rises from time t1 and gradually approaches Vin.

  When power reception stops at time t2, the power storage unit 30 starts discharging. In this state, the input voltage Vin to the load circuit 20 becomes about 4.4 V due to the voltage drop due to the On resistance of the FET Q2 and the voltage drop due to the forward voltage of the diode Dc.

  Thereafter, the voltage of the power storage unit 30 gradually decreases, and Vin also decreases accordingly. When Vin becomes less than 3.9 V, Q2 is turned off, and the power storage unit 30 is cut off (disconnected). As a result, Vin decreases rapidly. Therefore, insufficient voltage Vin is not continuously applied to the load circuit, and malfunction of the load circuit is prevented. Further, when Vin increases due to the subsequent start of power reception, the power-on reset is activated and the load circuit starts normally.

<< Third Embodiment >>
In the third embodiment, specific circuit examples of the cutoff circuit 40 and the quick charging circuit 50 different from the second embodiment are shown.

  FIG. 7 is a circuit diagram of a cut-off circuit and a quick charge circuit of the wireless power receiving apparatus according to the third embodiment. The reference point on the reference potential side of the voltage detection circuit 51 is different from the wireless power receiving apparatus shown in FIG. In the present embodiment, the reference potential side of the voltage detection circuit 51 is connected to the DC-DC converter CNV and the ground of the load circuit 20.

  According to the present embodiment, the voltage detection circuit 51 for the quick charge circuit is not affected by the voltage drop in the FET Q2 for the cutoff circuit. Therefore, rapid charging can be started with higher accuracy when Vin increases.

<< Fourth Embodiment >>
In the fourth embodiment, an example in which an FET is used as a switch of the quick charge circuit will be described.

  FIG. 8 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving apparatus according to the fourth embodiment. The quick charging circuit is different from the wireless power receiving apparatus shown in FIG. In the present embodiment, the transistor Q4, the resistors R51 and R52, and the FET Q5 constitute a switch for a quick charging circuit (see SW2 in FIG. 1A).

  When Vin becomes equal to or higher than the second threshold voltage Vth2 (4.0 V), the base-emitter current of the transistor Q4 flows and Q4 is turned on. When Q4 is turned ON, the gate potential of the FET Q5 is lowered, and Q5 is turned ON. As a result, a rapid charging current flows through the path of the DC-DC converter CNV → Q5 → 30 → Q2.

  The bias resistors (resistors R51 and R52 in the example of FIG. 8) can be made high resistance as compared with the case of using bipolar transistors, that is, current-driven transistors as shown in FIG. 5 and FIG. The power loss due to the bias resistor can be reduced.

<< Fifth Embodiment >>
In the fifth embodiment, an example in which an N-channel FET is used as a switch of the quick charge circuit is shown. In addition, an example in which the connection form of the fast charge circuit FET and the cutoff circuit FET is different from that of the fourth embodiment is shown.

  FIG. 9 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving apparatus according to the fifth embodiment. In the present embodiment, the transistor Q3 and the FET Q6 constitute a switch for a quick charging circuit (see SW2 in FIGS. 1A and 1B). The FET Q6 is an N-channel FET like the FET Q2.

  When Vin becomes the second threshold voltage Vth2 (4.0 V) or higher, the base-emitter current of the transistor Q3 flows, and Q3 is turned on. By turning on Q3, the gate potential of the FET Q6 rises and Q6 is turned on. As a result, a rapid charging current flows through the path of the DC-DC converter CNV → 30 → Q6 → Q2.

  In general, since the N-channel FET has a lower ON resistance than the P-channel FET, according to the present embodiment, the power loss in the quick charging circuit 50 can be further reduced.

<< Sixth Embodiment >>
In the sixth embodiment, an example in which the voltage detection circuit of the quick charging circuit and the cutoff circuit is shared is shown.

  FIG. 10 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving device according to the sixth embodiment. In the present embodiment, the voltage detection circuit 41 using the resistors R11 and R12 is a voltage detection circuit for a quick charge circuit and a voltage detection circuit for a cutoff circuit. In the present embodiment, the first threshold voltage Vth1 and the second threshold voltage Vth2 have the same value (for example, 3.95 V).

  When Vin becomes the second threshold voltage Vth2 (3.95 V) or more, the base-emitter current of the transistor Q1 flows, and Q1 is turned on. When Q1 is turned on, a current flows through the path of the body diode from Q1 → R2 → FETQ2, and the voltage between the gate and source of Q2 increases and Q2 is turned on. Further, the gate potential of the FET Q6 rises and Q6 is turned ON. As a result, a rapid charging current flows through the path of the DC-DC converter CNV → 30 → Q6 → Q2.

  When Vin becomes lower than the first threshold voltage Vth1 (3.95 V), the transistor Q1 is turned off, and thereby Q2 and Q6 are turned off.

  According to the present embodiment, the number of circuit elements can be reduced, and the size and cost can be reduced.

<< Seventh Embodiment >>
In the seventh embodiment, an example in which a bipolar transistor is used for the cutoff circuit is shown.

  FIG. 11 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving apparatus according to the seventh embodiment. The configuration of the cutoff circuit is different from the wireless power receiving apparatus shown in FIG. In this embodiment, the transistors Q1 and Q2, resistors R2 and R13, and the diode D2 constitute a switch for a cutoff circuit (see SW1 in FIG. 1A). Here, the resistor R13 limits the base current of the transistor Q2, and the diode D2 constitutes the base current path of the transistor Q2. The configuration other than this interruption circuit is the same as the circuit shown in FIG. 5 in the second embodiment.

  When Vin becomes equal to or higher than the first threshold voltage Vth1 (3.9 V), the base-emitter current of the transistor Q1 flows, Q1 is turned on, and the current flows through the path of Q1 → R13 → Q2 → diode D2. , Q2 base-emitter current flows, and Q2 is turned ON.

  When the power storage unit 30 is discharged, a discharge current flows through a route of 30 → Dc → Ro → Q2 → 30. When Vin becomes less than the first threshold voltage Vth1 (3.9 V), Q1 and Q2 are turned OFF, the voltage of the power storage unit 30 is cut off, and Vin rapidly decreases. Further, the electric charge of the power storage unit 30 is retained.

  As described above, the switch of the cutoff circuit may be formed of a bipolar transistor. Changing the switch of the cutoff circuit to a bipolar transistor can be similarly applied to any of the wireless power receiving apparatuses shown in FIGS.

<< Eighth Embodiment >>
In the eighth embodiment, while using a single circuit for detecting the input voltage, switching between supply / cutoff of the power supply voltage from the power storage unit to the load circuit and rapid charging are performed with two thresholds of the input voltage. An example of a power receiving apparatus that switches execution / stop is shown.

  FIG. 12 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving device according to the eighth embodiment. This embodiment differs from the circuit shown in FIG. 10 in the sixth embodiment in that a voltage dividing ratio switching circuit 61 is provided. The voltage detection circuit 41 turns on the transistor Q1 when the input voltage Vin is equal to or higher than the second threshold voltage Vth2 (4.0) V. Other configurations are the same as those of the circuit shown in the sixth embodiment.

  In FIG. 12, a voltage detection circuit 41 using resistors R11 and R12 is a voltage detection circuit for a quick charging circuit and a voltage detection circuit for a cutoff circuit. However, in the present embodiment, the first threshold voltage Vth1 and the second threshold voltage Vth2 are different.

  The voltage dividing ratio switching circuit 61 includes a resistance voltage dividing circuit including resistors R41 and R42, and a series circuit of a resistor R1, a diode D1, and a transistor Q1 connected in parallel to the resistor R41. The voltage dividing ratio switching circuit 61 includes a shunt regulator SR connected in series to the resistors R11 and R12, and a capacitor C1 connected between the reference voltage input terminal and the cathode terminal of the shunt regulator SR.

  The operation of the circuit shown in FIG. 12 is as follows.

  The voltage divided by the resistors R41 and R42 is input as a reference voltage for the shunt regulator SR. Therefore, the current flowing between the anode and cathode of the shunt regulator SR is determined according to the reference voltage. The anode-cathode current increases as the reference voltage increases.

  When the input voltage Vin becomes equal to or higher than the second threshold voltage Vth2 (4.0 V), the base-emitter voltage of the transistor Q1 exceeds the threshold value, and Q1 is turned on.

  When Q1 is turned on, a current flows through the path of the body diode from Q1 → R2 → FETQ2, and the voltage between the gate and source of Q2 increases and Q2 is turned on. Further, the gate potential of the FET Q6 rises and Q6 is turned ON. As a result, a rapid charging current flows through the path of the DC-DC converter CNV → 30 → Q6 → Q2.

  On the other hand, when the transistor Q1 is turned on, the series circuit of the transistor Q1, the diode D1, and the resistor R1 is connected in parallel to the resistor R41.

  FIGS. 13A and 13B are diagrams illustrating the voltage division ratio switching of the voltage division ratio switching circuit 61 in accordance with the state of the transistor Q1. When the transistor Q1 is OFF, as shown in FIG. 13A, the voltage dividing ratio of the voltage dividing ratio switching circuit 61 becomes a voltage dividing ratio determined by the resistors R41 and R42. In this state, the threshold value for turning on the transistor Q1 is the second threshold voltage Vth2 (4.0 V). When the transistor Q1 is ON, as shown in FIG. 13B, the voltage dividing ratio of the voltage dividing ratio switching circuit 61 is substantially a voltage dividing ratio determined by the parallel circuit of the resistor R1 and the resistor R41 and the resistor R42. The threshold value at which the transistor Q1 is turned off in this state is the first threshold voltage Vth1 (3.9 V).

  FIG. 14 is a flowchart showing the state transition of the transistor Q1, FETs Q2, Q6 in accordance with the input voltage Vin of the load circuit. FIG. 15 is a diagram illustrating state transition of connection / disconnection of the power storage unit 30 according to the input voltage Vin of the load circuit.

  When the input voltage Vin becomes equal to or higher than the second threshold voltage Vth2 (4.0 V), the transistor Q1 is turned on, whereby Q2 and Q6 are turned on. That is, power storage unit 30 is connected. Thereafter, this connection state is maintained until the input voltage Vin becomes less than 3.9V. When the input voltage Vin becomes less than the first threshold value Vth1 (3.9 V), the transistor Q1 is turned off, thereby turning off Q2 and Q6. That is, the power storage unit 30 is shut off.

  By the voltage division ratio switching operation of the voltage division ratio switching circuit 61 described above, hysteresis occurs in the state transition of connection / cutoff of the power storage unit 30. The capacitor C1 is a negative feedback circuit and is provided for stabilizing the operation of the shunt regulator SR.

  FIG. 16 is a waveform diagram of the input voltage Vin of the load circuit and the charging voltage (both ends voltage) Vc of the power storage unit 30. When power reception starts at time t1, the input voltage Vin of the load circuit rises rapidly, and when Vin exceeds 4.0V, both Q2 and Q6 are turned on, and the power storage unit 30 is rapidly charged. .

  When power reception stops at time t2, the power storage unit 30 starts discharging. In this state, since the FETs Q2 and Q6 are both ON, there is no voltage drop due to the body diode of the FET. When compared with the waveform diagram shown in FIG. 6 in the second embodiment, it can be seen that there is no Vin voltage drop after t2.

  According to the present embodiment, it is not necessary to separately provide a voltage detection circuit for a quick charging circuit and a voltage detection circuit for a cutoff circuit, so that the size and cost can be reduced by reducing the number of components. Further, since there is no voltage drop due to the body diode of the FET in the discharge state of the power storage unit 30, the discharge time (usable time) of the power storage unit 30 can be extended accordingly.

<< Ninth embodiment >>
The ninth embodiment shows an example in which the configuration of the voltage division ratio switching circuit is different from the example shown in the eighth embodiment.

  FIG. 17 is a circuit diagram of a cutoff circuit and a quick charging circuit of the wireless power receiving apparatus according to the ninth embodiment. The voltage dividing ratio switching circuit 62 provided in the circuit of this embodiment is obtained by replacing the shunt regulator SR in the voltage dividing ratio switching circuit 61 shown in FIG. 12 with a transistor Q7.

  In FIG. 17, the divided voltage by resistors R41 and R42 is input between the base and emitter of transistor Q7. Therefore, the collector current flowing through transistor Q7 is determined according to the base voltage. The collector current increases as the base voltage increases.

  When the input voltage Vin becomes equal to or higher than a second threshold voltage Vth2 (for example, 4.0 V), the base-emitter current of the transistor Q1 flows and the transistor Q1 is turned on. Once the transistor Q1 is turned on, the voltage dividing ratio of the voltage dividing ratio switching circuit 62 changes, and this connection state is maintained until the input Vin becomes less than 3.9V. When the input voltage Vin becomes less than the first threshold value Vth1 (3.9 V), the transistor Q1 is turned off, thereby turning off Q2 and Q6.

  By the above operation of the voltage division ratio switching circuit 62, the entire circuit operates in the same manner as in the eighth embodiment.

<< Tenth Embodiment >>
In the tenth embodiment, a power feeding system other than a wireless mouse will be described.

  FIG. 18 is a block diagram of a power supply system according to the eighth embodiment. Unlike the wireless power feeding system shown in FIGS. 1A and 1B in the first embodiment, the power receiving apparatus 108 is directly connected to the power transmitting apparatus 208. The power transmission device 200 is, for example, an automobile or bicycle generator (alternator). The voltage generated from this generator varies greatly depending on the engine speed and the like. The load circuit 20 of the power receiving apparatus 108 is, for example, a car or bicycle light.

  The power receiving unit 10 of the power receiving device 108 includes a rectifying / smoothing circuit 12 and a voltage stabilizing circuit 13. When the power transmission device 208 is a generator that generates a DC voltage, such as a dynamo, the rectifying and smoothing circuit 12 is not necessary. The structure of the interruption | blocking circuit 40 and the quick charge circuit 50 is the same as what was shown in 1st Embodiment.

  As shown in the present embodiment, the power receiving device of the present invention is not limited to the wireless power receiving device, and in the power feeding system from the power transmitting device to the power receiving device, the power feeding system in which the received voltage can be unstable depending on the usage pattern Applicable to.

  The power storage unit 30 is not limited to the one including the EDLC, and the present invention can be applied even when the power storage unit 30 is configured by a chemical secondary battery or other capacitors.

  Finally, the description of the above embodiment is illustrative in all respects and not restrictive. Those skilled in the art can make modifications and changes as appropriate. For example, partial replacements or combinations of the configurations shown in the different embodiments are possible. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

CNV ... DC-DC converter Co1 ... Capacitors Crs1, Crs2, Crs3 ... Capacitors Dc, Dp, D1, D2 ... Diodes Dr1, Dr2, Dr3 ... Diodes Ls1, Ls2, Ls3 ... Receiving coil PTC ... Positive thermistors Q1, Q3, Q4 , Q7 ... transistors Q2, Q5, Q6 ... FET
R11, R12, R13 ... resistors R1, R2 ... resistors R31, R32, R33 ... resistors R41, R42 ... resistors R51, R52 ... resistors Rc ... resistor Ro ... load circuit SW1, SW2 ... switch Vc ... charge voltage Vin ... load circuit Input voltage Vth1 ... 1st threshold value Vth2 ... 2nd threshold value ZDp ... Zener diode 10 ... Power receiving part 11 ... Resonance part 12 ... Rectification smoothing circuit 13 ... Voltage stabilization circuit 20 ... Load circuit 30 ... Power storage part 40 ... Cut off Circuit 41 ... Voltage detection circuit 50 ... Rapid charging circuit 51 ... Voltage detection circuit 61, 62 ... Voltage division ratio switching circuit 100A, 100B ... Wireless power reception device 108 ... Power reception device 200 ... Power transmission device 208 ... Power transmission device 211 ... Power transmission unit

Claims (7)

A power receiving device comprising: a power receiving unit that receives power from a power transmitting device; and a power storage unit that is provided between the power receiving unit and a load circuit and charges output power of the power receiving unit,
A cutoff circuit that shuts off the power storage unit from the load circuit when an input voltage of the load circuit falls below a first threshold ;
A rapid charging circuit that increases a current supplied to the power storage unit when the input voltage exceeds a second threshold value that is higher than the first threshold value;
A voltage dividing circuit for detecting the input voltage;
Equipped with a,
The cutoff circuit has a first switch element connected to the power storage unit,
The quick charging circuit includes a second switch element connected to the power storage unit,
A switch circuit that turns on when the input voltage exceeds the second threshold and turns on the first switch element and the second switch element;
A voltage dividing ratio switching circuit that switches a voltage dividing ratio of the voltage dividing circuit by turning on the switch circuit and turns off the switch circuit when the input voltage falls below the first threshold;
The power receiving device further comprising: It said first switching element connected in series to the power storage unit, the power receiving device according to claim 1. The second switch element connected in series to the power storage unit, the power receiving device according to claim 1 or 2. The power receiving device according to any one of claims 1 to 3 , further comprising a resistance element connected in parallel to the second switch element. It said power storage unit includes an electric double layer capacitor, the power receiving device according to any one of claims 1 to 4. The power receiving unit, the transmitting device receives power wirelessly from the power receiving device according to any one of claims 1 to 5. The power receiving device according to claim 6 , wherein the load circuit is a mouse circuit, and the power receiving unit receives power from the power transmitting device provided on a mouse pad.

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