JP2014212581A - Battery charger and charging stand, and battery charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breakdown due to a high voltage while reducing heat generation by lowering a withstand voltage of a switching element constituting a rectifier circuit in a state without charging a battery.SOLUTION: A battery charger and a charging stand is composed of a battery charger 50 having a power-receiving coil 51 for charging a battery 45 and a charging stand 10 having a power-transmitting coil 11 electromagnetic-coupled to the power-receiving coil 51 and supplying charging power. The battery charger 50 includes: a rectifier circuit 53 rectifying an alternating current induced into the power-receiving coil 51 and converting the alternating current into a direct current for charging the battery 45; a modulation circuit 61 transmitting a modulation signal to the charging stand 10 by modulation that changes the load impedance of the power-receiving coil 51; and a load resistance 56 connected to an output side of the rectifier circuit 53. In the battery charger 50, the load resistance 56 is connected to the output side of the rectifier circuit 53, and the modulation signal is transmitted to the charging stand 10 by changing the load impedance of the power-receiving coil 51 with the modulation circuit 61.

Description

  The present invention relates to a battery charger that charges a built-in battery such as a pack battery or a mobile phone, and a charging stand that conveys electric power to the battery charger by electromagnetic induction and charges the battery with the battery charger.

  A charging stand for charging a battery by transferring power from a power transmission coil to a power reception coil by the action of electromagnetic induction has been developed. (See Patent Document 1)

  The charging stand incorporates a power transmission coil that is excited by an AC power source, and the battery charger includes a power receiving coil that is electromagnetically coupled to the power transmission coil. The battery charger is built in a pack battery or a mobile phone and charges the battery. This battery charger rectifies the alternating current induced in the power receiving coil, and supplies this to the battery to charge the battery. In this charging method, a battery pack with a built-in battery charger or a mobile phone can be placed on a charging stand to charge the battery in a non-contact state.

  The method of transmitting the charging power of the battery from the charging stand by electromagnetically coupling the power transmission coil and the receiving coil is transmitted from the battery charger side to the charging stand and the power is transmitted on the charging stand side. It is necessary to stop power supply to the coil and stop charging the battery. Further, even during battery charging, battery information such as battery voltage, charging current, and temperature can be transmitted to the charging stand and charged in an ideal state.

  In order to realize this, a modulation method has been developed in which the load impedance of the power receiving coil is changed by battery information and the battery information is transmitted as a modulation signal to a charging stand. (See Patent Document 2)

JP-A-9-63655 JP 2010-288431 A

  The structure described in the publication of Patent Document 2 changes the load impedance with the modulation signal of the power receiving coil and transmits battery information to the charging base, so that the charging base accurately detects the state of the battery to be charged. The power transmitted from the power transmission coil to the power reception coil can be controlled to an optimum state. This method can detect a modulation signal by detecting a change in load impedance of a power receiving coil by a voltage change, a current change, and a power change of a power transmission coil that supplies an AC signal. That is, it is necessary to detect battery information by detecting a change in the AC power while supplying AC power to the power transmission coil. By the way, this modulation method needs to transmit battery information as a modulation signal from the battery charger to the charging stand even when the battery is not charged. For example, before starting charging a set battery, until the battery serial number or standard is confirmed, or when the battery temperature is higher than the set temperature and charging is suspended, the battery charger Battery information needs to be transmitted from the battery to the charging stand.

  When power is transferred from the power transmission coil to the power receiving coil in a state where charging of the battery is stopped, that is, in a state where the load of the rectifier circuit of the battery charger is opened, the voltage induced in the unloaded power receiving coil is considerably high. Become. When the induction voltage of the power receiving coil is increased, the voltage input to the rectifier circuit is increased, which causes a problem that the switching element of the rectifier circuit is destroyed by the high voltage. This adverse effect can be solved by using a high withstand voltage element as the switching element, but the high withstand voltage element has a large on-resistance and heat generation due to Joule heat in a state where the battery is charged increases. Therefore, an element having a low on-resistance and a low withstand voltage is used as the switching element. In particular, a synchronous rectifier circuit using a switching element as an FET can considerably reduce the on-resistance by using an FET having a low withstand voltage as the switching element. However, a low breakdown voltage FET has a negative effect of being destroyed by the voltage when the receiving coil is unloaded and the input voltage becomes high.

  Furthermore, in the circuit configuration in which the low breakdown voltage FET is used as the switching element of the rectifier circuit, the zener diode is connected to the output side of the rectifier circuit, so that the voltage breakdown of the FET can be prevented without charging the battery. However, this circuit configuration causes a problem that the Zener diode consumes power and generates heat to a high temperature without charging the battery.

  The present invention was developed for the purpose of solving the above drawbacks with a simple circuit configuration. An important object of the present invention is to prevent breakdown due to high voltage of the element while reducing the withstand voltage of the switching element constituting the rectifier circuit and reducing heat generation without charging the battery. In a circuit configuration for connecting a battery charger, a battery charger and a charging stand capable of transmitting battery information and the like as a modulation signal from the battery charger to the charging stand while reducing heat generation of the Zener diode, and a battery charger are provided. It is in.

Means for Solving the Problems and Effects of the Invention

  The battery charger and charging stand according to the present invention supply charging power by electromagnetically coupling to the battery chargers 50 and 70 including the power receiving coil 51 for charging the battery 45 and the power receiving coil 51 of the battery chargers 50 and 70. The charging stand 10 includes a power transmission coil 11. The battery chargers 50 and 70 charge the modulation signal with a rectifier circuit 53 that rectifies the alternating current induced in the power receiving coil 51 and converts it into direct current that charges the battery 45, and modulation that changes the load impedance of the power receiving coil 51. A modulation circuit 61 that transmits to the base 10 and a load resistor 56 connected to the output side of the rectifier circuit 53 are provided. The battery chargers 50 and 70 connect the load resistor 56 to the output side of the rectifier circuit 53, change the load impedance of the power receiving coil 51 with the modulation circuit 61, and transmit the modulation signal to the charging stand 10.

  According to the above configuration, in a state where the battery is not charged, the breakdown voltage of the switching element constituting the rectifier circuit can be lowered to reduce heat generation, and the element can be prevented from being damaged by a high voltage. This is because the voltage on the output side of the rectifier circuit can be prevented from being increased by the load resistance by connecting the load resistor to the rectifier circuit. Since the output voltage of the rectifier circuit cannot be increased by the load resistance when the battery is not charged, the switching element of the rectifier circuit is turned on with a low withstand voltage without using a switching element with a high withstand voltage and a large on-resistance. FETs and diodes with low resistance can be used. For this reason, the voltage destruction of a switching element can be prevented, reducing the emitted-heat amount of a rectifier circuit.

  In addition, according to the above configuration, in the circuit configuration in which the Zener diode is connected to the rectifier circuit, the battery information is transmitted from the battery charger to the charging stand as a modulation signal to the charging stand while reducing the heat generation of the Zener diode. it can. This is because the load resistor is connected in parallel with the Zener diode, and the output current of the rectifier circuit is divided into the Zener diode and the load resistor, so that the current of the Zener diode can be reduced. The Zener diode passes a load current through the rectifier circuit and clamps the output voltage at a constant level. At this time, if a load resistor is connected in parallel with the Zener diode, the current flows in a state where the output voltage of the rectifier circuit is clamped to a constant voltage and is shunted to the Zener diode and the load resistor. The output voltage of the rectifier circuit can be clamped to a constant voltage by reducing the current. Since the amount of heat generated by the Zener diode, that is, Joule heat increases in proportion to the flowing current, the amount of generated heat can be reduced by reducing the current.

  As described above, in a state in which the battery is not charged, a circuit for connecting a zener diode without destroying the voltage of the low withstand voltage switching element of the rectifier circuit while carrying power from the power transmitting coil of the charging stand to the power receiving coil. In the configuration, the heat generated by the Zener diode can be reduced. Therefore, even when the battery is not charged, power can be conveyed from the power transmission coil to the power reception coil. For this reason, in this state, the load impedance of the power receiving coil is changed, and battery information and the like can be transmitted as a modulation signal from the battery charger to the charging stand. The charging stand controls the AC power supplied to the power transmission coil with signals such as battery information transmitted from the battery charger, and always charges the battery in an ideal state via the battery charger. You can stop.

In the battery charger and the charging stand of the present invention, the rectifier circuit 53 can be a synchronous rectifier circuit 53A using the FET 53a as a switching element.
According to the above circuit configuration, the heat generation of the switching element of the rectifier circuit can be further reduced. This is because an FET having a smaller on-resistance than a diode can be used as a switching element, and the on-resistance can be further reduced by lowering the breakdown voltage of the FET.

The battery charger and the charging stand of the present invention can be connected to the Zener diode 57 on the output side of the rectifier circuit 53.
According to the above circuit configuration, the output voltage of the rectifier circuit can always be clamped to a constant voltage with the Zener diode, and the rectifier circuit can prevent a high voltage from being applied to the switching element regardless of the state of the load.

The battery charger and charging stand according to the present invention include a load switch 58 that connects the load resistor 56 to the output side of the rectifier circuit 53, and a control circuit 52 that controls the load switch 58 to be turned on and off. In the state, the control circuit 52 can turn on the load switch 58 to connect the load resistor 56 to the load side of the rectifier circuit 53.
According to the above circuit configuration, the battery can be efficiently charged with the output of the rectifier circuit without any power loss due to the load resistance in the state of charging the battery. This is because the load resistor can be connected to the rectifier circuit only when the battery is not charged, and the load resistor can be controlled not to be connected to the rectifier circuit when the battery is charged.

The battery charger and the charging stand according to the present invention include a load impedance changing circuit 62 in which a modulation circuit 61 is connected in parallel with the power receiving coil 51, and a modulation capacitor 63 and a modulation switch 64 are connected in series. And a control circuit 65 for switching the modulation switch 64 of the load impedance changing circuit 62 on and off. The control circuit 65 can switch the modulation switch 64 on and off and transmit the modulation signal to the charging base 10.
In the above circuit configuration, since the modulation capacitor is connected to the output side to change the load impedance of the power receiving coil, the load impedance of the power receiving coil is changed without consuming power by the modulation capacitor. The modulation signal can be transmitted from the battery to the charging stand.

The battery charger and the charging stand according to the present invention include a detection circuit 17 in which the charging stand 10 detects a change in the load impedance of the power receiving coil 51 changed by the modulation circuit 61 via the power transmission coil 11 to detect a modulation signal. Can be provided.
According to the above circuit configuration, a change in the load impedance of the power receiving coil that is changed by the modulation circuit can be reliably detected as a modulation signal by the detection circuit of the charging stand via the power transmission coil.

  In the battery charger and charging stand of the present invention, the modulation signal transmitted to the charging stand 10 by the modulation circuit 61 is such that the voltage of the battery 45 being charged, the charging current, the battery temperature, the serial number, and the battery 45 The allowable charging current for specifying the charging current, the allowable temperature for controlling the charging of the battery 45, and either the output voltage or the output current of the battery charger 70 can be included.

  The battery charger of the present invention includes a power receiving coil 51 that is electromagnetically coupled to a power transmission coil 11 built in the charging stand 10 and charges the battery 45 with electric power conveyed from the power transmission coil 11. The battery charger rectifies the alternating current induced in the power receiving coil 51 to convert it into direct current for charging the battery 45, and modulates the load signal of the power receiving coil 51 with the modulation signal to the charging base 10. A modulation circuit 61 for transmission and a load resistor 56 connected to the output side of the rectifier circuit 53 are provided. The battery charger connects the load resistor 56 to the output side of the rectifier circuit 53, changes the load impedance of the power receiving coil 51 with the modulation circuit 61, and transmits the modulation signal to the charging stand 10.

It is a perspective view of the battery charger and charging stand concerning one Example of this invention. It is a block diagram of the battery charger and charging stand concerning one Example of this invention. It is a block diagram of the battery charger and charging stand concerning the other Example of this invention. It is a block diagram of the battery charger concerning the other Example of this invention. It is a circuit diagram which shows an example of the position detection controller of a charging stand. It is a figure which shows an example of the echo signal output from the receiving coil excited with the position detection signal.

  Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment shown below exemplifies a battery charger and a charging stand for embodying the technical idea of the present invention, and the present invention does not specify the battery charger and the charging stand as follows. . Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the examples are indicated in the “claims” and “means for solving problems” sections. It is added to the members. However, the members shown in the claims are not limited to the members in the embodiments.

  1 to 4 show a perspective view and a block diagram of the battery chargers 50 and 70 and the charging stand 10. The charging stand 10 has battery chargers 50 and 70 arranged on the upper surface, and as shown in FIG. 2, charges the battery 45 built in the battery charger 50 by electromagnetic induction, or FIG. 3 and FIG. As shown in FIG. 4, the battery 45 built in the battery built-in apparatus 40 provided with the battery charger 70 is charged by electromagnetic induction. The battery chargers 50 and 70 have a power receiving coil 51 that is electromagnetically coupled to the power transmitting coil 11. The battery chargers 50 and 70 charge the battery 45 with the electric power induced in the power receiving coil 51. The battery built-in device 40 shown in FIG. 3 incorporates a battery 45 as a battery pack 41 so that the battery pack 41 can be replaced. Here, the battery charger 50 including the battery 45 shown in FIG. 2 can be a pack battery or an electronic device, and the battery charger 70 including the battery charger 70 and the battery 45 shown in FIGS. The device 40 may be an electronic device such as a mobile phone or an IC player, or may be a battery pack.

  The battery chargers 50 and 70 include a rectifier circuit 53 that rectifies the alternating current induced in the power receiving coil 51 and converts the alternating current into a direct current that charges the battery 45, and changes the load impedance of the power receiving coil 51 to change the modulation signal to the charging base 10. And a load resistor 56 connected to the output side of the rectifier circuit 53.

  The rectifier circuit 53 converts alternating current input from the power receiving coil 51 into direct current. The direct current output of the rectifier circuit 53 is supplied to the battery 45. 2 and 3 is a synchronous rectifier circuit 53A in which a switching element is an FET. The synchronous rectifier circuit 53A includes four FETs 53a connected to the bridge, and a switching circuit 53b that controls on / off of each FET 53a. The switching circuit 53b switches the FET 53a in synchronization with the alternating current output from the power receiving coil 51, converts the input alternating current to direct current, and outputs the direct current. Since the voltage drop of the FET 53a is smaller than that of the diode, the synchronous rectifier circuit 53A can perform rectification more efficiently than the diode bridge and reduce power loss due to the voltage drop. However, it goes without saying that a diode bridge 53B can be used for the rectifier circuit 53 in place of the synchronous rectifier circuit as shown in FIG.

  Further, the rectifier circuit 53 of FIGS. 2 to 4 has a Zener diode 57 connected to the output side. The Zener diode 57 clamps the output voltage of the rectifier circuit 53 to a constant voltage and prevents a high voltage from being applied to the switching element of the rectifier circuit 53. The Zener voltage of the Zener diode 57 is higher than the voltage at which the battery 45 can be charged. For example, in a battery charger that charges a lithium ion battery, the Zener voltage is set to about 5 V while charging the battery. Limit the output voltage to 5V. However, the Zener voltage of the Zener diode is set to a voltage that is higher and lower than the voltage that can charge the battery in consideration of the voltage of the battery to be charged.

  The rectifier circuit 53 shown in FIGS. 2 to 4 has a Zener diode 57 connected to the output side to clamp the output voltage of the rectifier circuit 53 to the Zener voltage to prevent voltage breakdown of the switching element. In a state in which the load resistor 56 is not connected, the output current of the rectifier circuit 53 is shunted to the load resistor 56 and the Zener diode 57, and heat generation of the load resistor 56 can be reduced. However, the battery charger of the present invention does not necessarily need to connect a Zener diode to the output side of the rectifier circuit. This is because the load resistance connected to the output side of the rectifier circuit can limit the output voltage of the rectifier circuit to prevent voltage breakdown of the switching element.

  The rectifier circuit 53 of FIGS. 2 to 4 has a load resistor 56 connected to the output side of the rectifier circuit 53 via a load switch 58. The load switch 58 is controlled to be turned on / off by the control circuit 52. The control circuit 52 turns on the load switch 58 when the battery 45 is not charged, and turns it off when the battery 45 is charged. However, the control circuit 52 can also connect the load resistor 56 to the output side of the control circuit 52 by switching the load switch 58 on in a state where the charging current of the battery 45 is smaller than the set value. For example, a lithium ion battery reduces the charging current as it approaches full charge. Therefore, when charging is started, the load switch 58 is turned off to charge the lithium ion battery efficiently, and the charging current approaches the full charge. In the small state, the load switch 58 can be turned on.

  In this circuit configuration, the load resistor 56 is connected only when the battery 45 is not charged or when the charging current of the battery 45 is small, and when the battery 45 is charged or when the charging current of the battery is larger than the set value. Since the load resistor 56 is not connected, the battery 45 can be efficiently charged with the output of the rectifier circuit 53. However, the load resistor 56 can always be connected to the rectifier circuit 53 without going through the load switch 58. The load resistor 56 is set to an electric resistance that limits the output of the rectifier circuit 53 and prevents the Zener diode 57 from generating heat, for example, about 10Ω. However, the electrical resistance of the load resistor can be in the range of 5Ω to 500Ω.

  The battery chargers 50 and 70 shown in FIGS. 2 to 4 have the output side of the rectifier circuit 53 connected to the battery 45 via the output cutoff switch 54. 2 and 4, the battery charger 50 has a load resistor 56 connected to the battery side which is the output side of the output cutoff switch 54, or the input of the output cutoff switch 54 as shown in FIG. 3. A load resistor 56 can be connected to the rectifier circuit 53 side. As shown in FIGS. 2 and 4, the circuit configuration in which the load resistor 56 is connected to the output side of the output cutoff switch 54 is such that the output cutoff switch 54 is turned on and the output cutoff switch 54 is turned on when the battery 45 is not charged. A load resistor 56 is connected to the output side of the rectifier circuit 53.

  The battery charger 50 shown in FIG. 2 charges the battery 45 by directly supplying the power output from the rectifier circuit 53 to the battery 45. The battery built-in device 40 shown in FIGS. 3 and 4 includes a charge control circuit 44 between the output terminal 71 that is the output of the built-in battery charger 70 and the battery 45, and the charge control circuit 44 is The battery 45 is charged with the power output from the battery charger 70. The charge control circuit 44 detects full charge of the battery 45 and stops charging. The charge control circuit 44 that charges the battery 45, which is a lithium ion battery, fully charges the battery 45 by constant voltage / constant current charging. A charge control circuit for charging a nickel metal hydride battery is charged at a constant current to fully charge the battery.

  Further, the battery built-in device 40 shown in FIGS. 3 and 4 is connected to an adapter 80 that converts commercial power (AC 100 V) into direct current (for example, DC 5 V), and the battery 45 is supplied with power supplied from the adapter 80. It has a structure that can be charged. The battery built-in device 40 shown in the figure is connected to a power supply terminal 47 for connecting an adapter 80 to a positive / negative input line 48 connected to an output terminal 71 of the battery charger 70 on the input side of the battery 45. . The battery built-in device 40 is supplied from the adapter 80 by connecting the adapter 80 to the power terminal 47 when the battery 45 is not charged via the charging stand 10, that is, when the non-contact battery charger 70 is not used. The supplied electric power can be supplied to the charge control circuit 44 to charge the battery 45.

  The modulation circuit 61 includes a voltage of the battery 45 being charged, a charging current, a battery temperature, a serial number, an allowable charging current value that allows charging of the battery 45, an allowable temperature that controls charging of the battery 45, and the battery charger 70. The impedance of the power receiving coil 51 is changed by information such as output voltage or output current, an output increase instruction signal, an output decrease instruction signal, an output stop instruction signal, or the like. That is, the modulation circuit 61 changes the load impedance of the power receiving coil 51 with information or signals to be transmitted. The charging stand 10 includes a detection circuit 17 that detects a change in the load impedance of the power receiving coil 51 that is changed by the modulation circuit 61 via the power transmission coil 11 to detect information and signals.

  The modulation circuit 61 includes a load impedance change circuit 62 in which a modulation switch 64 of a semiconductor switching element is connected in series to a modulation capacitor 63 connected in parallel with the power receiving coil 51, and a modulation switch of the load impedance change circuit 62. And a control circuit 65 for switching 64 on and off with information and signals. The control circuit 65 switches the modulation switch 64 on and off according to information and signals, and transmits information and signals to the charging base 10. The control circuit 65 is a battery such as a voltage of the battery 45 being charged, a charging current, a battery temperature, a battery serial number, an allowable charging current for specifying the charging current of the battery, and an allowable temperature for controlling the charging of the battery. Information, power supply information such as output voltage and output current output from the battery charger 70, and instruction signals such as output increase, output decrease, and output stop, which are requests to the charging stand 10, are used as digital signals, and modulation switches 64 is controlled and transmitted.

  The battery charger 50 shown in FIG. 2 includes a battery information detection circuit 46 that detects battery information of the battery 45. With the battery information detection circuit 46, the serial number, authenticity determination, battery voltage, and charge of the battery 45 are provided. Battery information such as current and battery temperature is detected and input to the control circuit 52. The control circuit 52 inputs the battery information input from the battery information detection circuit 46 to the control circuit 65.

  Further, in the structure in which the battery charger 70 and the battery 45 are built in the battery built-in device 40, as shown in FIG. 3, the battery pack 41 including the battery 45 and the battery information detection circuit 46 is built in the battery built-in device 40. Alternatively, as shown in FIG. 4, the battery built-in device 40 includes a battery information detection circuit 46 that detects battery information of the battery 45. These battery built-in devices 40 control the charging of the battery 45 by inputting the battery information detected by the battery information detection circuit 46 to the charge control circuit 44. Further, the battery charger 70 shown in FIGS. 3 and 4 includes a power supply information detection circuit 72 that detects information on the power output from the battery charger 70 and supplied to the charge control circuit 44. The power supply information detection circuit 72 is provided on the output side of the battery charger 70, and is provided between the output cutoff switch 54 and the output terminal 71 in FIG. 3, and in FIG. Is provided between the connection point of the load resistor 56 and the output terminal 71. The power supply information detection circuit 72 detects power supply information such as the output voltage and output current from the battery charger 70 and inputs the power supply information to the control circuit 52. The control circuit 52 inputs the power supply information input from the power supply information detection circuit 72 to the control circuit 65.

  The control circuit 65 repeats at a predetermined cycle, that is, transmits information and signals by repeating a transmission timing for transmitting information and signals and a non-transmission timing at which information and signals are not transmitted at a predetermined cycle. This period is set to, for example, 0.1 sec to 5 sec, preferably 0.1 sec to 1 sec. In the state where the battery 45 is charged, the remaining capacity, voltage, current, temperature, and further the output voltage and output current of the battery charger 70 change, so that such information is repeated at the above-mentioned cycle. Battery information such as battery serial number, allowable charging current that specifies battery charging current, and allowable temperature that controls battery charging, is transmitted only at the beginning of charging, and then repeatedly transmitted There is no need.

  At the transmission timing, the modulation circuit 61 switches the modulation switch 64 on and off with a digital signal indicating information and signals, and modulates the parallel capacitance of the power receiving coil 51 to transmit information and signals. For example, the control circuit 65 provided in the modulation circuit 61 controls on / off of the modulation switch 64 at a speed of 1000 bps to transmit information and signals. However, the control circuit 65 can also transmit information and signals at 500 bps to 5000 bps. After information and signals are transmitted at 1000 bps at the transmission timing, transmission of information and signals is stopped and the battery is charged in a normal state at non-transmission timing. At the transmission timing, the modulation switch 64 is switched on and off.

  A modulation capacitor 63 is connected to the power receiving coil 51 in order to transmit information and signals. Since the modulation capacitor 63 is connected in parallel to the power reception coil 51, the efficiency of power transfer from the power transmission coil 11 to the power reception coil 51 is slightly reduced from the designed optimum state. However, the transmission timing is shorter than the non-transmission timing, and the timing at which the modulation capacitor 63 is connected to the power receiving coil 51 is very short even at this transmission timing. Even if the power transfer efficiency is reduced in a state where the power is connected, the reduction in power transfer efficiency can be almost negligible in the total time.

  As shown in FIGS. 1 to 4, the charging stand 10 detects information and signals transmitted from the power transmission coil 11, the AC power supply 12 that supplies AC power to the power transmission coil 11, and the battery chargers 50 and 70. And a detection circuit 17 for performing the above operation.

  The power transmission coil 11 is wound in a spiral shape on a surface parallel to the upper surface plate 21 and radiates an alternating magnetic flux above the upper surface plate 21. The power transmission coil 11 radiates an alternating magnetic flux orthogonal to the upper surface plate 21 above the upper surface plate 21. The power transmission coil 11 is supplied with AC power from the AC power source 12 and radiates AC magnetic flux above the upper surface plate 21.

  For example, the AC power supply 12 supplies high-frequency power of 20 kHz to several MHz to the power transmission coil 11. The AC power supply 12 is controlled by the detection circuit 17 and controls the AC power output to the power transmission coil 11.

  The detection circuit 17 detects the impedance change of the power receiving coil 51 from the voltage level change or / and the current level change of the power transmission coil 11 and detects information and signals from the impedance change. When the impedance of the power receiving coil 51 changes, the power transmission coil 11 is electromagnetically coupled to the power receiving coil 51, so that the voltage level and / or current level of the power transmission coil 11 changes. Since the voltage level and / or current level of the power transmission coil 11 changes in synchronization with the on / off of the modulation switch 64, the on / off state of the modulation switch 64 can be detected from the voltage level change or / and current level change of the power transmission coil 11. Since the modulation circuit 61 switches the modulation switch 64 on and off with a digital signal indicating information or a signal, the detection circuit 17 detects the digital signal indicating the information or signal by detecting the on / off of the modulation switch 64. From the detected digital signal, the voltage, current, temperature, etc. of the battery being charged can be detected.

  However, the detection circuit 17 can also detect information and signals from either a phase change with respect to the voltage of the current or a change value such as a change in transmission efficiency. This is because these characteristics of the power transmission coil 11 change due to the impedance change of the power reception coil 51.

Here, the battery charger 50 shown in FIG. 2 does not include a charge control circuit on the input side of the battery 45, but this battery charger 50 controls the charging of the battery 45 as follows.
When the battery charger 50 of FIG. 2 charges the battery 45 that is a lithium ion battery, the battery charger 50 performs constant voltage / constant current charging. When the battery charger 50 is charged at a maximum voltage of 4.2 V, for example, by battery information such as voltage and current input from the battery information detection circuit 46 to the control circuit 52, when the battery voltage is 4.2 V or less, The modulation circuit 61 transmits an output increase or decrease instruction signal to the charging base 10 so that the predetermined constant current is obtained, and the charging base 10 increases or decreases the output. When the battery voltage becomes 4.2 V, the modulation circuit 61 transmits an instruction signal for decreasing or increasing the output to the charging base 10, and the charging base 10 decreases or increases the output so that the battery voltage is reduced. Control so that 4.2V can be maintained.

  3 and 4 includes a charging control circuit 44 that controls constant voltage / constant current charging of the battery 45, so that the output from the non-contact battery charger 70 is an adapter. The output is controlled to be equivalent to the input from 80 (for example, DC5V). The battery charger 70 transmits power supply information such as output voltage and output current of the battery charger 70 input from the power supply information detection circuit 72 to the control circuit 52 to the charging base 10 by the modulation circuit 61, or For example, when the output voltage is less than 5V, the output increases, and when the output voltage is greater than 5V, the output of the battery charger 70 inputted from the power supply information detection circuit 72 to the control circuit 52 is equivalent to the output of the adapter 80. An instruction signal for lowering the output is transmitted to the charging stand 10.

  The charging stand 10 shown in the figure charges the battery 45 by arranging battery chargers 50 and 70 on the top plate 21. In order to charge the battery 45 efficiently, the charging stand 10 incorporates a mechanism for bringing the power transmission coil 11 close to the power reception coil 51 of the battery chargers 50 and 70, although not shown. The charging stand 10 includes a position detection controller 14 for detecting the position of the power receiving coil 51.

  2 and 3 show circuit diagrams of the charging stand 10 and the battery chargers 50 and 70 set on the charging stand 10. The charging stand 10 includes a position detection controller 14 that detects the position of the power receiving coil 51. FIG. 5 shows a block diagram of the position detection controller 14. The position detection controller 14 includes a plurality of position detection coils 30 fixed inside the upper surface plate 21 of the case 20 of the charging base 10, and a detection signal generation circuit 31 that supplies a position detection signal to the position detection coil 30. A reception circuit 32 that receives an echo signal that is excited by the position detection signal supplied from the detection signal generation circuit 31 to the position detection coil 30 and is output from the power reception coil 51 to the position detection coil 30; And an identification circuit 33 for determining the position of the power receiving coil 51 from the received echo signal. Further, the position detection controller 14 shown in the figure is controlled by the identification circuit 33 to switch the plurality of position detection coils 30 in order, and the position detection signal input from the detection signal generation circuit 31 to the reception circuit 32. And a limiter circuit 35 that inputs the signal level to the receiving circuit 32.

The above position detection controller 14 detects the position of the power receiving coil 51 as follows.
(1) The detection signal generation circuit 31 outputs a position detection signal of the pulse signal to the position detection coil 30.
(2) Excited by the pulse signal of the position detection signal supplied to the position detection coil 30, an echo signal is output from the power receiving coil 51 to the position detection coil 30, as shown in FIG.
(3) The echo signal is received by the receiving circuit 32.
(4) A plurality of position detection coils 30 are sequentially switched by the switching circuit 34 to output a position detection signal of a pulse signal from each position detection coil 30, and an echo signal is received by each position detection coil 30.
(5) The identification circuit 33 detects the level of the echo signal induced in each position detection coil 30 to detect the position of the power receiving coil 51. The echo signal induced in the position detection coil 30 approaching the power receiving coil 51 has a high level, and the level of the echo signal decreases as the power receiving coil 51 moves away from the position detection coil 30, so that the identification circuit 33 determines the level of the echo signal. From this, the position of the power receiving coil 51 is detected. The position detection controller 14 in FIG. 5 is provided with position detection coils 30 in the X-axis direction and the Y-axis direction, and the position of the power receiving coil 51 in the X-axis direction is determined by the X-axis detection coil 30A. It is detected by the Y-axis detection coil 30B.

  The above-described position detection controller 14 connects the modulation capacitor 63 in parallel with the power receiving coil 51 at the timing of detecting the position of the power receiving coil 51, as shown in the circuit diagrams of FIGS. A circuit 59 is configured to resonate with a pulse trigger and generate an echo signal. However, the modulation capacitor 63 connected in parallel with the power receiving coil 51 slightly lowers the power efficiency when charging the battery 45 with the power induced in the power receiving coil 51.

  The battery chargers 50 and 70 in FIGS. 2 to 4 include a series capacitor 55 connected in series to the power receiving coil 51, a modulation capacitor 63 connected in parallel to the power receiving coil 51, a series capacitor 55, and a modulation capacitor. A modulation switch 64 for switching the connection state between the capacitor 63 and the power receiving coil 51 is provided. In the battery chargers 50 and 70, when the position detection controller 14 outputs a position detection signal, the modulation capacitor 64 connects the modulation capacitor 63 to the power reception coil 51 and the power transmission coil 11 to the power reception coil 51. In the state where the power is transferred to the power supply circuit, the power receiving coil 51 and the modulation capacitor 63 are disconnected from each other, and the alternating current of the power receiving coil 51 is output to the rectifier circuit 53 via the series capacitor 55.

  As shown in the figure, the series capacitor 55 is connected between the modulation capacitor 63 and the power receiving coil 51 or, although not shown, can be connected to the rectifier circuit side of the modulation capacitor. The series capacitor 55 connected between the modulation capacitor 63 and the power receiving coil 51 is connected in series with the modulation capacitor 63 with the modulation switch 74 switched on. Therefore, the capacitance of the capacitor that realizes the parallel resonance circuit 59 with the power receiving coil 51 is a combined capacitance in which the series capacitor 55 and the two modulation capacitors 63 are connected in series.

  The battery chargers 50 and 70 and the charging stand 10 described above normally constitute a parallel resonance circuit 59 to accurately detect the position of the power receiving coil 51, and at the time of charging, the modulation capacitor 63 is disconnected to increase power efficiency. Thus, the battery 45 can be efficiently charged. The echo signal can be generated because the modulation capacitor 63 is connected in parallel with the power receiving coil 51 in a state where the position of the power receiving coil 51 is detected. In addition, the battery 45 can be charged efficiently by increasing the power efficiency. When the battery 45 is being charged, the capacitor is connected in series with the power receiving coil 51 without connecting the capacitor in parallel with the power receiving coil 51. This is because the power of the power receiving coil 51 can be output to the rectifier circuit 53 by connecting 55. The circuit configuration in which the series capacitor 55 is connected to the power receiving coil 51 improves the power efficiency and suppresses the heat generation of the coil and the battery during charging, as compared with the circuit configuration with a small transmission current connected to the power receiving coil. Can be charged efficiently, promptly and safely.

  The battery charger 50 described above uses the modulation capacitor 63, the modulation switch 64, and the control circuit 65 provided as the modulation circuit 61 in combination with the position detection controller 14, and the position detection controller 14 uses the position of the power receiving coil 51. When detecting the modulation switch 64, the modulation switch 64 is turned on. For this reason, the battery charger 50 can detect the position of the power receiving coil 51 while transmitting information and signals to the charging stand 10 in an ideal state without increasing the manufacturing cost.

  In a state where the position of the power receiving coil 51 is detected, the control circuit 52 turns on the modulation switch 64 and connects the modulation capacitor 63 to the power receiving coil 51. The power receiving coil 51 connected in parallel with the modulation capacitor 63 is excited by the position detection signal output from the position detection coil 30 and outputs a high level echo signal.

  When the echo signal having the waveform as described above is detected, the charging base identification circuit 33 can recognize and identify that the power receiving coil 51 of the battery charger 50 is mounted. When a waveform different from the waveform of the echo signal is detected and identified, it is possible to stop the power supply assuming that something other than the power receiving coil 51 of the battery charger 50 (for example, a metal foreign object) is mounted. Further, when the waveform of the echo signal is not detected or identified, the power receiving coil 51 of the battery charger 50 is not mounted and power is not supplied.

  After the position of the power receiving coil 51 is detected and the power transmitting coil 11 is brought close to the power receiving coil 51, the control circuit 65 switches off the modulation switch 64 so that the modulation capacitor 63 is not connected to the power receiving coil 51. . That is, in the state where power is transferred from the power transmission coil 11 to the power reception coil 51, the control circuit 52 turns off the modulation switch 64 by the control circuit 65 to disconnect the modulation capacitor 63 from the power reception coil 51 and induces it to the power reception coil 51. The alternating current is efficiently output to the rectifier circuit 53 via the series capacitor 55.

  The above position detection circuit detects the position of the power receiving coil by the magnitude of the echo signal from the power receiving coil 51 with respect to the position detection signal of the pulse signal, but the position detection circuit is not shown, but the inductance and impedance of the power transmission coil are not shown. The position of the receiving coil of the battery charger can also be detected by the change.

  The above charging stand 10 includes a moving mechanism 13 that moves the power transmission coil 11 along the inner surface of the upper surface plate 21. The position detection controller 14 controls the moving mechanism 13 to charge the power transmission coil 11 with a battery. The power receiving coil 51 of the container 50 is moved closer. When the identification circuit 33 detects the position of the power receiving coil 51 in the X-axis direction and the Y-axis direction, the position detection controller 14 controls the moving mechanism 13 with the position signal from the identification circuit 33 to transmit the power transmission coil 11. Is moved to the position of the power receiving coil 51.

The charging stand 10 carries power to the battery charger 50 and charges the battery 45 by the following operation.
(1) When the battery charger 50 is disposed on the upper surface plate 21 of the case 20, the position of the battery charger 50 is detected by the position detection controller 14.
(2) The position detection controller 14 that has detected the position of the battery charger 50 controls the moving mechanism 13 to move the power transmission coil 11 along the upper surface plate 21 with the moving mechanism 13, so that the battery charger 50 Approach the power receiving coil 51.
(3) The power transmission coil 11 approaching the power reception coil 51 is electromagnetically coupled to the power reception coil 51 and carries AC power to the power reception coil 51.
(4) The battery charger 50 rectifies the AC power of the power receiving coil 51 and converts it to DC, and charges the battery 45 with this DC.

  The charging stand 10 supplies AC power to the power transmission coil 11 with the AC power supply 12 in a state where the position detection controller 14 controls the moving mechanism 13 to bring the power transmission coil 11 close to the power reception coil 51. The AC power of the power transmission coil 11 is transferred to the power reception coil 51 and used for charging the battery 45. The charging stand 10 shown in FIGS. 2 and 3 includes a detection circuit 17 that detects information and signals conveyed from the battery chargers 50 and 70. The detection circuit 17 charges the battery 45 by controlling the voltage and current for charging the battery 45 based on information and signals transmitted from the battery chargers 50 and 70. The full charge of the battery 45 is transmitted from the battery chargers 50 and 70 as battery information. Therefore, the detection circuit 17 detects the full charge of the battery 45 from the battery information transmitted from the battery chargers 50 and 70, stops the supply of AC power to the power transmission coil 11, and ends the charging.

  The above charging stand includes a position detection circuit and a moving mechanism, and the position detecting mechanism detects the positions of the power receiving coils arranged on the top plate in the X-axis direction and the Y-axis direction, and the moving mechanism detects the power transmitting coil. Move it to the desired position. Since this charging stand can approach the power receiving coil to the power receiving coil, it can efficiently carry power from the power transmitting coil to the power receiving coil. However, the present invention does not specify the structure of the charging stand as a mechanism that detects the position of the power receiving coil and moves the power transmitting coil to the position of the power receiving coil. By placing the battery charger at a specific position on the charging base without bringing the power transmission coil close to the position of the power receiving coil, the charging base can be brought into a state where the power receiving coil can be brought close to the power transmitting coil and electromagnetically coupled. Furthermore, the power transmission coil can be enlarged, and the battery charger can be set on the charging stand so that the power reception coil is disposed inside the large power transmission coil, so that the power transmission coil and the power reception coil can be electromagnetically coupled. In these charging stands, the user presses a set switch (not shown) to detect that the battery charger is set, and supplies AC power from the AC power source to the power transmission coil, or the battery charger is set. This is electrically detected or physically detected by a limit switch or the like, and power is supplied from the AC power source to the power transmission coil.

DESCRIPTION OF SYMBOLS 10 ... Charging stand 11 ... Power transmission coil 12 ... AC power supply 13 ... Moving mechanism 14 ... Position detection controller 17 ... Detection circuit 20 ... Casing 21 ... Top plate 30 ... Position detection coil 30A ... X-axis detection coil
30B ... Y-axis detection coil 31 ... Detection signal generation circuit 32 ... Reception circuit 33 ... Identification circuit 34 ... Switching circuit 35 ... Limiter circuit 40 ... Battery built-in device 41 ... Battery pack 44 ... Charge control circuit 45 ... Battery 46 ... Battery information detection Circuit 47 ... Power supply terminal 48 ... Input line 50 ... Battery charger 51 ... Receiving coil 52 ... Control circuit 53 ... Rectifier circuit 53A ... Synchronous rectifier circuit
53a ... FET
53b ... Switching circuit
53B ... Diode bridge 54 ... Output cutoff switch 55 ... Series capacitor 56 ... Load resistor 57 ... Zener diode 58 ... Load switch 59 ... Parallel resonant circuit 61 ... Modulation circuit 62 ... Load impedance change circuit 63 ... Modulation capacitor 64 ... Modulation switch 65 ... Control circuit 70 ... Battery charger 71 ... Output terminal 72 ... Power supply information detection circuit 80 ... Adapter

Claims (8)

Battery chargers (50) and (70) having a power receiving coil (51) for charging the battery (45) and the power receiving coil (51) of the battery chargers (50) and (70) are electromagnetically coupled to charge power. A charging stand (10) having a power transmission coil (11) for supplying
The battery charger (50), (70) is a rectifier circuit (53) for rectifying the alternating current induced in the power receiving coil (51) and converting the direct current to charge the battery (45), and the power receiving coil (51). A modulation circuit (61) for transmitting a modulation signal to the charging base (10) by modulation for changing the load impedance of the load, and a load resistor (56) connected to the output side of the rectifier circuit (53). ,
The battery charger (50), (70), the load resistance (56) is connected to the output side of the rectifier circuit (53), the modulation circuit (61) changes the load impedance of the power receiving coil (51) A battery charger and a charging stand configured to transmit a modulation signal to the charging stand (10).   The battery charger and charging stand according to claim 1, wherein the rectifier circuit (53) is a synchronous rectifier circuit (53A) having an FET (53a) as a switching element.   The battery charger and charging stand according to claim 1 or 2, wherein a Zener diode (57) is connected to the output side of the rectifier circuit (53). A load switch (58) for connecting the load resistor (56) to the output side of the rectifier circuit (53), and a control circuit (52) for controlling the load switch (58) on and off,
The control circuit (52) switches the load switch (58) on to connect the load resistor (56) to the load side of the rectifier circuit (53) when the battery (45) is not charged. The battery charger and charging stand described in any one of 3. The modulation circuit (61) is connected in parallel with the power receiving coil (51), a load impedance change circuit (62) formed by connecting a modulation capacitor (63) and a modulation switch (64) in series, A control circuit (65) for switching on and off the modulation switch (64) of the load impedance change circuit (62),
The battery charger and charging according to any one of claims 1 to 4, wherein the control circuit (65) switches the modulation switch (64) on and off to transmit a modulation signal to the charging stand (10). Stand.   A detection circuit (17) for detecting a modulation signal by detecting, through the power transmission coil (11), a change in load impedance of the power receiving coil (51), wherein the charging base (10) is changed by the modulation circuit (61). A battery charger and a charging stand according to any one of claims 1 to 5.   The modulation signal transmitted by the modulation circuit (61) to the charging base (10) includes the voltage of the battery (45), the charging current, the battery temperature, the serial number, and the tolerance for specifying the charging current of the battery (45). The battery charger according to any one of claims 1 to 6, including a charging current, an allowable temperature for controlling charging of the battery (45), and an output voltage or output current of the battery charger (70). And charging stand. A battery charger comprising a power receiving coil (51) that is electromagnetically coupled to a power transmission coil (11) built in a charging stand (10) and charges a battery (45) with power carried from the power transmission coil (11). There,
A rectifier circuit (53) that rectifies the alternating current induced in the power receiving coil (51) and converts the direct current to charge the battery (45), and a modulation signal that modulates the load impedance of the power receiving coil (51). A modulation circuit (61) for transmitting to the charging base (10), and a load resistor (56) connected to the output side of the rectifier circuit (53),
A load resistor (56) is connected to the output side of the rectifier circuit (53), and the modulation circuit (61) changes the load impedance of the receiving coil (51) and transmits the modulation signal to the charging stand (10). Battery charger made like this.

Images