JP2011182538A - Charger and charging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charger and a charging system which carry out charging as securely as possible depending on the power supply capacity of a transmission system. <P>SOLUTION: A charge current control circuit 105 of a charger 100 has a high circuit resistance value R2 when a DC voltage V1 output from a rectifying circuit 102 is high, and has a low circuit resistance value R2 when the DC voltage V1 becomes low. A charge control unit 103 supplies an output current value Iout of a given constant current to a secondary battery 104 based on the DC voltage V1. When the circuit resistance value R2 of the charge current control circuit 105 is high, the charge control unit 103 supplies the output current value Iout as a high current value. When the circuit resistance value R2 of the charge current control circuit 105 becomes low, the charge control unit 103 supplies the output current value Iout as a low current value. By controlling the output current value Iout to be low in this manner, the DC voltage V1 is recovered to a given level and maintained so as to enable continuous charging. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a charging device that includes a secondary battery and charges the secondary battery with electric power supplied from the outside, and a charging system including the charging device.

  At present, many types of non-contact charging are in practical use. The non-contact charging is not to supply power using an electrical contact that is generally performed in the past, but to supply power using electromagnetic coupling or the like.

  In such a contactless charging system, a power transmission device including a primary coil is placed on a table or the like. A user places a portable terminal provided with a charging device including a secondary battery and a secondary coil close to the power transmission device. Thereby, the primary side coil and the secondary side coil are electromagnetically coupled, power is supplied to the charging device side, and the secondary battery is charged.

  By the way, the basic principle of such a non-contact charging system is the same, but the specifications differ depending on each system. For example, the current value during charging varies from system to system.

  And as a structure which enables charge in general with respect to such a plurality of non-contact charging systems, there are systems shown in the inventions of Patent Document 1 and Patent Document 2. In these systems, the power transmission device (primary device) acquires the specifications of the charging device (secondary device). The power transmission device switches the amount of supplied power according to the acquired specification of the charging device.

JP 2008-206233 A JP 2008-206327 A

  However, in the configuration shown in Patent Document 1 and Patent Document 2 described above, the power transmission device must perform power transmission control according to the specifications of the charging device, which complicates the configuration of the power transmission device and increases costs. turn into. In addition, when there is a request for exceeding the power supply capability of the power transmission device, the power transmission device cannot respond and power supply is stopped.

  FIG. 1 is a diagram for explaining the problems of the conventional configuration. As shown in FIG. 1, for example, when the charging device has a configuration capable of rapid charging with a current value of 1 A and power of 5 W, and the power transmission device can handle only with a current value of 0.5 A and power of 2.5 W, The input voltage of the charge control circuit that supplies a constant current to the battery is lowered to the operating voltage or less. For this reason, the electric power feeding from a power transmission apparatus to a secondary battery stops.

  In view of such a problem, it is an object of the present invention to realize a charging device and a charging system that can perform charging as reliably as possible according to the power supply capability of the power transmission device.

  The present invention relates to a charging device, and the charging device includes a power reception unit, a charging control unit, and a charging current control circuit. The power receiving unit receives power from the outside and generates a charging voltage. The charging control unit supplies a constant current to the secondary battery based on the charging voltage. The charging current control circuit controls the current value of the constant current supplied by the charging control unit based on the voltage value of the charging voltage.

  In this configuration, the voltage value of the charging voltage can be variably set by setting the current value of the constant current supplied to the secondary battery by the charging current control circuit. For example, when the current value to the secondary battery is too large and the charging voltage decreases, the amount of current can be reduced and the charging voltage can be recovered. Thereby, the minimum voltage level which can supply an electric current to a secondary battery by a charge control circuit can be ensured more reliably. Therefore, continuous charging can be more reliably performed without causing charging stoppage due to insufficient power supply capacity.

  The charging current control circuit of the charging device according to the present invention is a circuit for determining a divided voltage that is a reference for the current value of the constant current. The charging current control circuit has a circuit configuration in which the circuit resistance of the circuit that determines the divided voltage based on the charging voltage is variable.

  This configuration shows a specific configuration of the charging current control circuit. By using this configuration, the above-described control can be performed with a circuit that only makes the circuit resistance variable. That is, the above-described operation can be obtained with a relatively simple circuit configuration.

  The charging current control circuit of the charging device according to the present invention includes a plurality of resistance elements and switching elements. The charging current control circuit varies the value of the circuit resistance by performing on / off control of the switch element based on the charging voltage.

  This configuration shows a more specific configuration of the charging current control circuit. By using this configuration, the circuit that enables the above-described control is configured by a plurality of resistance elements and switch elements, and thus the above-described operation can be realized with a simpler circuit configuration.

  The charging current control circuit of the charging device according to the present invention includes a variable resistance element that changes the resistance value based on the charging voltage.

  In this configuration, the circuit resistance can be set in more detail by using the variable resistance element. As a result, the constant current can be set to the maximum current value at which a necessary charging voltage can be obtained. That is, charging as fast (high speed) as possible becomes possible.

  The power receiving unit of the charging device according to the present invention includes an external coupling coil.

  This configuration shows a specific structural example of the charging device, and shows a case of a charging device that performs non-contact charging by electromagnetic coupling using an external coupling coil.

  In addition, the present invention includes a power transmission device that transmits predetermined power from a primary coil, and a charging device that includes a secondary coil coupled to the primary coil and receives the power to charge a secondary battery. It relates to a charging system. The charging device of the charging system includes a power receiving unit that generates a charging voltage from supply power obtained by the secondary coil, a charging control unit that supplies a constant current to the secondary battery based on the charging voltage, and a charging voltage A charging current control circuit that controls a current value of a constant current supplied by the charging control unit based on the voltage value.

  With this configuration, in the contactless charging system in which the power transmission device and the charging device perform power transmission in a contactless manner, the current value of the supply current to the secondary battery can be variably controlled on the charging device side according to the transmission power. Thereby, even if it does not change transmission power by the power transmission apparatus side, the secondary battery can be more reliably continuously charged by the charging apparatus side. That is, charging is performed more reliably according to the specifications of the power transmission device.

  In addition, the charging current control circuit of the charging device in the charging system of the present invention is a circuit that determines a divided voltage that is a reference for the current value of the constant current. The charging current control circuit has a circuit configuration in which the circuit resistance of the circuit that determines the divided voltage based on the charging voltage is variable.

  Further, the charging current control circuit of the charging device in the charging system of the present invention includes a plurality of resistance elements and switch elements, and the switch resistance is turned on and off based on the charging voltage, whereby the value of the circuit resistance is determined. Make it variable.

  The charging current control circuit of the charging device in the charging system of the present invention includes a variable resistance element that changes the resistance value based on the charging voltage.

  In these configurations, as described above, the specific configuration of the charging current control circuit of the charging device in the charging system is shown.

  In the charging system of the present invention, the power transmission device includes a primary side authentication control unit, and the charging device includes a secondary side authentication control unit. The secondary side authentication control unit outputs an authentication result with the primary side authentication control unit to the charging current control circuit. The charging current control circuit controls the constant current value based on the authentication result and the charging voltage.

  In this structure, the specific example in the case of performing an authentication process in the above-mentioned charging system is shown. In this configuration, the charging specification can be determined on the charging device side in consideration of the authentication result. For example, if the authentication result is “OK” and sufficient charging voltage is obtained, rapid charging is performed. If the authentication result is “OK” and sufficient charging voltage is not obtained, the battery is supplied to the secondary battery. Reduce the current to perform charging (standard charging). If the authentication result is “NG”, charging is stopped or standard charging is performed even if a sufficient charging voltage is obtained. As described above, the charging specification can be variably set by adding additional information to the charging voltage as basic information.

  According to the present invention, since the charging device can variably control the current value of the supply current to the secondary battery according to the supplied power, charging is performed as reliably as possible according to the power supply capability of the power transmission device. be able to.

It is a figure for demonstrating the problem of the conventional structure. It is a block diagram which shows the main structures of the non-contact charging system 900 which concerns on 1st Embodiment. 3 is a specific circuit diagram of a component including a charge control circuit 103 and a charge current control circuit 105. FIG. It is a flowchart which shows the charge flow of the charging device 100 of 1st Embodiment. It is a block diagram which shows the main structures of the non-contact charge system 900A which concerns on 2nd Embodiment. It is a truth table of the logic control part 154A of this embodiment. It is a block diagram which shows the main structures of the non-contact charging system 900B which concerns on 3rd Embodiment. It is a flowchart which shows the charge flow of the charging device 100B of 3rd Embodiment.

  A non-contact charging system according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram illustrating a main configuration of the non-contact charging system 900 according to the present embodiment.

  The non-contact charging system 900 includes a power transmission device 200 and a power reception device 100. Specifically, for example, the power transmission device 200 is built in a charging stand or the like fixedly installed on a table. On the other hand, the power receiving apparatus 100 is built in a portable terminal or the like.

  The power transmission device 200 includes a transmission side driver circuit 202 and a primary side antenna coil 201. An AC adapter 300 is connected to the transmission side driver circuit 202. The transmission side driver circuit 202 is driven by receiving power from the AC adapter 300. The transmission-side driver circuit 202 generates a primary-side signal for performing power feeding and communication with respect to a mobile terminal including the power receiving device 100 and causes a primary-side current to flow through the primary-side antenna coil 201. Since the primary side signal has various specifications and is known, the description is omitted.

  The power receiving apparatus 100 includes a secondary antenna coil 101, a rectifier circuit 102, a charging control circuit 103, a secondary battery 104, and a charging current control circuit 105.

  When a portable terminal including the power receiving device 100 is placed on a charging stand including the power transmitting device 200, the secondary side antenna coil 101 of the power receiving device 100 and the primary side antenna coil 201 of the power transmitting device 200 approach each other. In this state, when the primary side current flows through the primary side antenna coil 201, the primary side antenna coil 201 and the secondary side antenna coil 101 are electromagnetically coupled, and the secondary side current according to the primary side current and the degree of coupling. Is excited by the secondary antenna coil 101. The secondary current excited by the secondary antenna coil 101 is input to the rectifier circuit 102.

  The rectifier circuit 102 rectifies and smoothes the AC voltage based on the secondary side current, and outputs the DC voltage V <b> 1 to the charge control circuit 103. The DC voltage output to the charging control circuit 103 corresponds to “charging voltage”. The DC voltage V1 is also applied to the charging current control circuit 105.

  The charging current control circuit 105 includes fixed resistors R2a and R2b and a switch 153, and the circuit resistance value changes when the switch 153 is turned on / off according to the DC voltage value. That is, if the switch 153 is turned on, a resistor parallel circuit composed of the fixed resistors R2a and R2b is formed, and the combined resistance value of the resistor parallel circuit becomes the circuit resistance value of the charging current control circuit 105. On the other hand, if the switch 153 is off, the circuit includes only the fixed resistor R2a, and the resistance value of the fixed resistor R2a becomes the circuit resistance value of the charging current control circuit 105. Thereby, the circuit resistance value of the charging current control circuit 105 changes according to the voltage level of the DC voltage V1. For example, as will be described in detail later, the circuit resistance value is maintained high when the value of the DC voltage V1 is high, and the circuit resistance value functions when the value of the DC voltage V1 is low.

  The charge control circuit 103 performs constant current control using the input DC voltage V <b> 1 so that an output current value Iout composed of a desired constant current flows to the secondary battery 104. The charging control circuit 103 determines the current value of the output current Iout based on the circuit resistance value of the charging current control circuit 105. Here, the circuit resistance value of the charging current control circuit 105 changes according to the DC voltage V1 as described above. Therefore, the charging control circuit 103 makes the output current Iout variable according to the change of the DC voltage V1.

  Specifically, the output current Iout is variably set by configuring the charging control circuit 103 and the charging current control circuit 105 as follows. FIG. 3 is a specific circuit diagram of a component composed of the charge control circuit 103 and the charge current control circuit 105.

  The charge control circuit 103 includes a pnp transistor Q1, operational amplifiers OP1 and OP2, fixed resistors Rb, Rs, and R1, and a reference voltage input terminal. A DC voltage V1 is applied to the emitter of the pnp transistor Q1. The collector of the pnp transistor Q1 is connected to the non-inverting input terminal of the operational amplifier OP1. The inverting input terminal of the operational amplifier OP1 is connected to the secondary battery 104. A fixed resistor Rs is connected between the non-inverting input terminal and the inverting input terminal of the operational amplifier OP1.

  The output terminal of the operational amplifier OP1 is connected to the non-inverting input terminal of the operational amplifier OP2. An inverting input terminal of the operational amplifier OP2 is connected to a connection point between the fixed resistor R1 and the charging current control circuit 105. A reference voltage input terminal is connected to a terminal of the resistor R1 opposite to the charging current control circuit 105 side. The output terminal of the operational amplifier OP2 is connected to the base of the pnp transistor Q1 through the fixed resistor Rb.

  The charging current control circuit 105 includes a fixed resistor R2a, a fixed resistor R2b, and a switch 153. The switch 153 includes an inversion logic unit 154, a sample hold unit 155, and a semiconductor switch element Q2 including an FET. The semiconductor switch element Q2 has a source grounded, and a drain connected to the fixed resistor R2b. A series circuit of the fixed resistor R2b and the semiconductor switch element Q2 is connected in parallel to the fixed resistor R2a. The terminal opposite to the ground side of the parallel circuit is connected to the fixed resistor R1 of the charging control circuit 103.

  A sample hold unit 155 is connected to the gate of the semiconductor switch element Q2, and an inversion logic unit 154 is connected to the sample hold unit 155. A DC voltage V1 is applied to the inverting logic unit 154.

  First, the operation of the charging control circuit 103 will be described assuming that the charging current control circuit 105 is the resistor R2. When a predetermined DC voltage V1 is applied and the output current Iout increases beyond a desired current value (a target current value determined by the reference voltage Vref and the circuit resistance value R2 of the charging current control circuit 105), it is fixed. The voltage ΔV generated in the resistor Rs increases. When the voltage ΔV increases, the potential difference between the non-inverting input terminal and the inverting input terminal of the operational amplifier OP2 increases, and the output voltage Vso1 of the operational amplifier OP1 increases.

  A divided voltage with respect to the reference voltage Vref of the fixed resistor R1 and the resistor R2 (charging current control circuit 105) is applied to the inverting input terminal of the operational amplifier OP2. That is, a divided voltage corresponding to the circuit resistance value R2 of the charging current control circuit 105 is applied.

  The operational amplifier OP2 performs a differential between the output voltage Vso1 of the operational amplifier OP1 and the divided voltage corresponding to the circuit resistance value R2 of the charging current control circuit 105, and outputs the output voltage Vso2. Therefore, when the output voltage Vso1 of the operational amplifier OP1 increases, the output voltage Vso2 of the operational amplifier OP2 also increases.

  When the output voltage Vso2 of the operational amplifier OP2 increases, the base current of the pnp transistor Q1 decreases and the emitter-collector voltage Vce1 of the pnp transistor Q1 increases. When the emitter-collector voltage Vce1 of the pnp transistor Q1 increases, the potential of the non-inverting input terminal of the operational amplifier OP1 decreases and the output current Iout also decreases.

  Although explanation is omitted, when the output current Iout is lower than the target current value, the charging control circuit 103 operates to increase the output current Iout contrary to the above. Thus, the output current Iout is held so as to be constant at the target current value. The output current value Iout controlled by this process can be expressed as follows.

  In the above equation, G is a loop gain of the charge control circuit 103 determined by the transistor Q1 and the operational amplifiers OP1 and OP2.

  As can be seen from (Equation 1), the output current value Iout of the charging control circuit 103 is determined according to the circuit resistance value R2 of the charging current control circuit 105. In other words, the output current value Iout can be variably controlled by appropriately setting the circuit resistance value R2 of the charging current control circuit 105.

  Next, the determination operation of the circuit resistance value R2 of the charging current control circuit 105 will be described. A DC voltage V <b> 1 is input to the inverting logic unit 154. The inverting logic unit 154 generates a Low level signal if the DC voltage V1 is greater than the threshold value Vcq, and generates a Hi level signal if the DC voltage V1 is less than or equal to the threshold value Vcq.

  When the sample hold unit 155 transits from the Low level signal to the Hi level signal, the sample hold unit 155 maintains the Hi level. The semiconductor switch element Q2 is off-controlled by the Low level signal and on-controlled by the Hi level signal.

  When the semiconductor switch element Q2 is controlled to be turned on, it becomes a parallel circuit of the fixed resistors R2a and R2b, and the circuit resistance value R2 of the charging current control circuit 105 becomes the parallel resistance value of the fixed resistor R2a and the fixed resistor R2b.

R2 (on) = R2a * R2b / (R2a + R2b) − (Formula 2)
On the other hand, when the semiconductor switch element 156 is controlled to be off, the circuit is only a fixed resistor R2a when viewed from the charge control circuit 103, and the circuit resistance value R2 of the charging current control circuit 105 is the resistance value of the fixed resistor R2a.

R2 (off) = R2a − (Formula 3)
Thereby, the charging current control circuit 105 acts as a resistor having a parallel resistance value of the fixed resistance R2a and the fixed resistance R2b if the DC voltage V1 is higher than the threshold value cq, and if the DC voltage V1 is equal to or lower than the threshold value Vcq. It acts as a resistor having the resistance value of the fixed resistor R2a. That is, a variable resistor whose resistance value is changed by the DC voltage V1 is obtained.

  Here, the parallel resistance value (resistance value based on Formula 2) of the fixed resistor R2a and the fixed resistor R2b is set to be lower than that of the fixed resistor R2a.

  Thus, if the DC voltage V1 is higher than the threshold value Vcq, the divided voltage of the charge control circuit 103 is relatively high. If the DC voltage V1 is equal to or less than the threshold value Vcq, the divided voltage of the charge control circuit 103 is relatively high. Lower. Therefore, if the DC voltage V1 is higher than the threshold value Vcq, the output current value Iout can be controlled to be high, and if the DC voltage V1 is equal to or less than the threshold value Vcq, the output current value Iout can be controlled to be low.

  With such a circuit configuration, the following control can be specifically performed. In addition, below, it shows about the case where the quick charge of 1.0A and 5.0W and the standard charge of 0.5A and 5.0W are selectively performed. Although specific numerical values are not described, the output current value Iout is 1.0 A when the divided voltage is high, and the output current value Iout is 0.5 A when the divided voltage is low. From (Equation 1), the reference voltage Vref, fixed resistors Rs and R1, fixed resistors R2a and R2b, and gain G are set.

  First, when the power transmission device 200 can be rapidly charged, the DC voltage V1 does not decrease even when the DC voltage V1 is applied and the output current value is set to 1.0A. Accordingly, the semiconductor switch element Q2 of the charging current control circuit 105 remains unchanged in the OFF state, and the circuit resistance value R2 of the charging current control circuit 105 does not change. Thereby, a high divided voltage is maintained. Thereby, rapid charge can be performed continuously.

  On the other hand, when the power transmission device 200 does not have the capability of rapid charging, that is, when it has only the charging capability of 0.5 A and 5 W, the output current value Iout is set at 1.0 A in the initial state, so the DC voltage V1 decreases.

  When the DC voltage V1 decreases and reaches the threshold value Vcq or less, the semiconductor switch element Q2 is turned on, and the circuit resistance value R2 of the charging current control circuit 105 decreases. As a result, the divided voltage of the charging control circuit 103 decreases, and the output current Iout decreases. As a result, charging (standard charging) can be performed continuously with the output current value Iout set to 0.5 A.

  As described above, by using the configuration and processing of the present embodiment, rapid charging is possible if the power transmission device 200 has the capability of rapid charging, and the power transmission device 200 has no capability of rapid charging, so standard charging is possible. If there is no ability, a charging device 100 that can be charged by standard charging can be realized. That is, the charging device 100 that can be more reliably charged can be realized according to the specifications on the power transmission device 200 side.

  Such processing will be described in an easy-to-understand manner using the flow of FIG. FIG. 4 is a flowchart showing a charging flow of the charging apparatus 100 of the present embodiment.

  First, when the charging device 100 is placed in the vicinity of the power transmission device 200, electric power is supplied from the power transmission device 100 by electromagnetic coupling, and the charging device 100 starts charging (S101). At this time, the charging device 100 starts charging with a quick charge specification (specification of a high current value (for example, 1.0 A)). If the DC voltage V1 is continuously maintained at a level higher than the threshold level Vcq (S102: Yes), the charging apparatus 100 continues charging with the quick charging specification as it is (S103). On the other hand, when the DC voltage V1 decreases and becomes equal to or lower than the threshold level Vcq (S102: No), the charging apparatus 100 decreases the circuit resistance value R2 of the charging current control circuit 105 as described above, thereby reducing the charging current. Lowering control is performed (S104).

  After the charging current reduction control, the charging device 100 continues to detect the DC voltage V1 continuously, and if the DC voltage V1 is continuously maintained at a level higher than the threshold level Vcq (S141: Yes), the standard as it is. Charging is continued with a charging specification (a specification with a low current value (for example, 0.5 A)) (S105). On the other hand, if the DC voltage further falls below the threshold level Vcq (S141: Yes), the charging control is stopped and the standby mode is set (S142). In the standby mode, even if power is supplied from the power transmission device 200 side, there is not enough power to drive the charging control unit 103, and charging is inevitably stopped, but power transmission from the charging device 100 to the power transmission device 200 is stopped. May be transmitted, and the power transmission apparatus 200 may stop power transmission. In addition, information indicating incompatibility of the power transmission device 100 may be output to the mobile terminal provided with the charging device 100 and the information may be displayed on the display screen of the mobile terminal.

  Next, the non-contact charging system according to the second embodiment will be described with reference to the drawings. FIG. 5 is a block diagram showing a main configuration of a contactless charging system 900A according to the present embodiment. The charging system 900A of the present embodiment is further provided with authentication control units 203 and 106 in the power transmission device 200A and the charging device 100A, respectively, and charging of the charging device 100A with respect to the charging system 900 shown in the first embodiment. The configuration of the current control circuit 105A is different.

  The authentication control unit 203 is connected to the primary side antenna coil 201, and the authentication control unit 106 is connected to the secondary side antenna coil 101. These authentication control units 203 and 106 transmit and receive authentication information via the primary side antenna coil 201 and the secondary side antenna coil 101. Thus, it is determined whether or not the charging device 100A is authenticated.

  The authentication control unit 106 of the charging apparatus 100A outputs Hi-level authentication data RESc if the authentication is OK, and outputs Low-level authentication data RESc if the authentication is NG. The output authentication data RESc is input to the logic control unit 154A of the switch 153A of the charging current control circuit 105A. The DC voltage V1 is also input to the logic control unit 154A.

  The logic control unit 154A generates a gate control signal Xo in accordance with the truth table shown in FIG. 6 based on the DC voltage V1 and the authentication data RESc. FIG. 6 is a truth table of the logic control unit 154A. As shown in FIG. 6, the gate control signal Xo is at a low level only when both the DC voltage V1 and the authentication data RESc are at a high level. On the other hand, if at least one of the DC voltage V1 and the authentication data RESc is at a low level, the gate control signal Xo is at a high level. The gate control signal Xo of the logic control unit 154A is output to the sample hold unit 155.

  When the gate control signal Xo transitions from the Low level to the Hi level, the sample hold unit 155 maintains the Hi level. The semiconductor switch element Q2 is off-controlled at the Low level and on-controlled at the Hi level.

  By using such a configuration and processing, the charging device 100A can perform quick charging only when the authentication is OK and the power transmission device 200A has a quick charging capability. That is, it is possible to rapidly charge only the charging device 100A that is previously permitted to the power transmission device 200A. In this embodiment, control is performed by the logic control unit 154A so that standard charging can be performed even when the authentication is NG. However, when the authentication is NG, the authentication control unit 106 transmits power to the power transmission device 200A. You may control transmission stop. Thereby, it is also possible not to charge a charging device that is not authenticated.

  Next, a charging system according to a third embodiment will be described with reference to the drawings. FIG. 7 is a block diagram showing the main configuration of the contactless charging system 900B of the present embodiment. The contactless charging system 900B of the present embodiment is different from the contactless charging system 900A of the second embodiment in a charging current control circuit 105B.

  The charging current control circuit 105B of the charging device 100B of this embodiment includes a series circuit of a fixed resistor R2a and a semiconductor switch element Q2A. The gate control signal X1 from the gate voltage control unit 157 is input to the gate of the semiconductor switch element Q2A.

  The gate voltage control unit 157 receives the authentication data RESc from the authentication control unit 106 and the DC voltage V1. The gate voltage control unit 157 outputs the gate control signal X1 while monitoring the DC voltage V1 only when the authentication data RESc indicates authentication OK. Specifically, at the beginning of charging, the gate control signal X1 is set to the lowest value, and when the DC voltage V1 becomes equal to or lower than the threshold value Vcq, the gate control signal X1 is gradually increased from the lowest value. If the DC voltage V1 continuously becomes larger than the threshold value Vcq, the gate control signal X1 is fixed to the level at this time. In this embodiment, authentication data is used. However, as in the first embodiment, the gate control signal X1 may be generated using only the DC voltage V1.

  The semiconductor switch element Q2A acts as a variable resistor according to the voltage level of the given gate control signal X1. Thereby, the circuit resistance value R2 of the charging current control circuit 105 can be continuously changed. Specifically, the circuit resistance value R2 becomes the maximum resistance value when the gate control signal X1 is the minimum value. The circuit resistance value R2 decreases as the gate control signal X1 increases. As a result, the output current value Iout gradually decreases from the configuration and processing of the charge control circuit 103 described above. When the DC voltage V1 is stabilized and the gate control signal X1 is fixed, the circuit resistance value R2 corresponding to the level is obtained. As a result, the output current value Iout corresponding to the fixed circuit resistance value R2 is stabilized.

  Thereby, the output current value Iout can be controlled so that the DC voltage V1 becomes a maximum current value that can be maintained at a predetermined value.

  Such processing will be described in an easy-to-understand manner using the flow of FIG. FIG. 8 is a flowchart showing a charging flow of the charging apparatus 100B of the present embodiment.

  First, when charging device 100B is placed in the vicinity of power transmission device 200A, power is supplied from power transmission device 100A by electromagnetic field coupling, and charging device 100B starts charging (S301). At this time, the charging device 100B starts charging with the fastest charging specification (specification of the maximum current value) that can be controlled by the own device. If the DC voltage V1 is continuously maintained at a level higher than the threshold level Vcq (S302: Yes), the charging device 100B continues charging with the same specifications (fastest charging specifications) (S303).

  On the other hand, in the charging apparatus 100B, if the DC voltage V1 decreases and becomes equal to or lower than the threshold level Vcq (S302: No), and the level Vgs2 of the gate control signal X1 does not reach the on-control threshold Vonth (S304: Yes). Then, the charging current reduction control is performed by reducing the circuit resistance value R2 of the charging current control circuit 105B (S305 → S302).

  If the charging device 100B continues to detect the DC voltage V1 continuously after the charging current reduction control and the DC voltage V1 is continuously maintained at a level higher than the threshold level Vcq (S302: Yes), one step is performed. The charging is continued in the state after the charging current lowering control (S303).

  On the other hand, if the DC voltage further decreases to the threshold level Vcq or less (S302: No), and the level Vgs2 of the gate control signal X1 does not reach the on-control threshold Vonth (S304: Yes), the charging current is further decreased. Control is performed (S305 → S302).

  The charging device 100B continuously executes such a charging current reduction control until the DC voltage V1 is continuously maintained at the threshold value Vcq or higher. Thereby, it can control so that it can charge continuously with the maximum electric current value which can be charged.

  However, when the level Vgs2 of the gate control signal X1 reaches the on-control threshold value Vonth (S304: No), since no further current reduction control is possible, the charge control is stopped and the standby mode is set (S306). In the standby mode, the same processing as in the first embodiment is performed.

  By using the configuration and processing as described above, it is possible to reliably charge with a current value as high as possible according to the power transmission capability of the power transmission device.

  In each of the above-described embodiments, the contactless charging system has been described as an example, but the technology can also be applied to a contact-type charging system.

  In the above-described embodiment, the semiconductor switch elements Q2 and Q2A are shown as variable resistors. However, other elements that function as variable resistor elements whose resistance is variable by application of a control signal, such as an electronic volume, are used. May be.

  In the above-described embodiment, an example in which the DC voltage V1 after rectification and smoothing is detected and used has been described. However, the voltage value before smoothing after rectification or after rectification may be detected and used. In this case, after rectification, a voltage level having a predetermined time length may be detected, and these voltage levels may be averaged. Further, before the rectification, the voltage level may be averaged after the absolute value is obtained.

  In the above description, the reset timing of the sample hold unit 155 is not described in detail. For example, the reset can be performed at a timing when charging is newly started or at a preset time interval. As a result, for example, even if the quick charging is possible after switching to the standard charging specification, the charging can be performed with the quick charging specification. If it is a specific example, it was charged with a power transmission device with a standard charging specification, but when it was replaced with a power transmission device with a quick charging specification, or even with a quick charging specification, the way of placing the charging device was bad, It is possible to deal with cases where quick charging is possible by replacing the charging device from the situation where charging was not possible with the standard charging specification.

900, 900A, 900B-charging system, 100, 100A, 100B-charging device, 101-secondary antenna coil, 102-rectifier circuit, 103-charging control circuit, 104-secondary battery, 105, 105A, 105B-charging Current control circuit, 153-switch, 154-inverting logic unit, 155-sample hold unit, 106-authentication control unit, 200, 200A-power transmission device, 200-primary side antenna coil, 202-transmission side driver circuit, 203- Authentication control unit, 300-AC adapter, R1, R2a, R2b, Rs, Rb—fixed resistor, Q2, Q2A—semiconductor switch element

Claims (10)

A power receiving unit that receives an external power supply and generates a charging voltage;
A charge controller for supplying a constant current to the secondary battery based on the charging voltage;
A charging current control circuit for controlling a current value of the constant current supplied by the charging control unit based on a voltage value of the charging voltage;
A charging device comprising: The charging current control circuit is a circuit that determines a divided voltage that serves as a reference for the current value of the constant current,
The charging device according to claim 1, comprising a circuit configuration in which a circuit resistance of a circuit that determines the divided voltage based on the charging voltage is variable.   3. The circuit according to claim 2, wherein the charging current control circuit includes a plurality of resistance elements and a switch element, and the switch resistance is varied on and off based on the charging voltage. Charging device.   The charging device according to claim 2, wherein the charging current control circuit includes a variable resistance element that changes a resistance value based on the charging voltage.   The charging device according to claim 1, wherein the power reception unit includes an external coupling coil. A charging system comprising: a power transmitting device that transmits predetermined power from a primary coil; and a charging device that includes a secondary coil coupled to the primary coil and that receives the power and charges a secondary battery,
The charging device is:
A power receiving unit that generates a charging voltage from the supply power obtained by the secondary coil;
A charge control unit for supplying a constant current to the secondary battery based on the charging voltage;
A charging current control circuit for controlling a current value of the constant current supplied by the charging control unit based on a voltage value of the charging voltage;
A charging system comprising: The charging current control circuit is a circuit that determines a divided voltage that serves as a reference for the current value of the constant current,
The charging system according to claim 6, comprising a circuit configuration in which a circuit resistance of a circuit that determines the divided voltage based on the charging voltage is variable.   8. The circuit according to claim 7, wherein the charging current control circuit includes a plurality of resistance elements and a switch element, and the switch resistance is varied on and off based on the charging voltage. 9. Charging system.   The charging system according to claim 7, wherein the charging current control circuit includes a variable resistance element that changes a resistance value based on the charging voltage. The power transmission device includes a primary side authentication control unit,
The charging device includes a secondary side authentication control unit,
The secondary side authentication control unit outputs an authentication result with the primary side authentication control unit to the charging current control circuit,
The charging system according to claim 6, wherein the charging current control circuit performs the control based on the authentication result and the charging voltage.