JP2013070581A - Resonance type wireless charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable power transmission to stop when charging has been completed, by appropriately detecting a charging state of a secondary battery on the transmission side without providing communication means on the transmission and reception sides.SOLUTION: A power transmission device 1 comprises: a high frequency power supply part 7; a power transmission primary coil 3 for transmitting AC power; a reflection power detection part 9 for detecting reflection power reflected from the power transmission primary coil; and a power supply controller 10 for controlling generation of the AC power. A power reception device 2 comprises: a power reception secondary coil 5 for receiving the AC power transmitted from the power transmission device; a rectifier 12 for rectifying the received AC power; and a charger 14 for charging a secondary battery by constant voltage after charging it by constant current by using DC power output by the rectifier. The power supply controller detects a time change rate of the reflection power and performs control so as to stop the transmission of the AC power, when the time change rate of the reflection power detected in the process of the constant voltage charging has become equal to or lower than a lower threshold RCL set correspondingly to a predetermined charge rate.

Description

  The present invention relates to a wireless charging device that charges a secondary battery in a non-contact manner using a power transmission technique based on magnetic field resonance.

  In recent years, wireless power transmission technology for electric vehicles, industrial devices, portable electronic devices, and the like has attracted attention. In particular, this technology is useful for electric appliances used around water such as electric toothbrushes and electric shavers, cordless telephones, mobile phones and the like, and is used in some products.

  A wireless charging device that is currently in practical use is an electromagnetic induction charging device that uses electromagnetic induction between a primary coil provided in a power transmission device and a secondary coil provided in a power receiving device. It is. In this apparatus, in order to increase the power transmission efficiency, it is necessary to arrange the coils provided in the devices on the power transmission side and the power reception side close to each other. For this reason, there is a problem that a distance in which power can be wirelessly transmitted is short.

  On the other hand, electric field / magnetic resonance type power transmission can supply power wirelessly to a device several meters away. In particular, in the case of the magnetic field resonance type, the human body hardly absorbs energy, and dielectric loss can be avoided. From this point of view, attention to the magnetic field resonance type is increasing.

  For example, Patent Document 1 discloses a technique for efficiently charging an automobile ignition key using resonance frequencies on a power transmission side and a power reception side. The technique disclosed in Patent Document 1 has a problem of dealing with changes in the resonance frequency on the power receiving side due to environmental conditions such as temperature and humidity, and supplies power of a plurality of frequency components separated at a certain interval from the power transmission side. Then, charging is performed at an optimal resonance frequency.

  However, the technique disclosed in Patent Document 1 does not have a configuration for stopping power transmission from the power transmission side when charging is completed, and the power transmission side continues power transmission. To cope with this, even if the power transmission side recognizes the completion of charging on the power receiving side and automatically attempts to stop power transmission, the power transmission side does not have means for detecting the charging state of the power receiving side. It is necessary to provide communication means in the device on the side. Such a configuration is unsuitable for downsizing and must be expensive.

  On the other hand, in Patent Document 2, in a wireless charging system that charges a battery mounted on a vehicle by transmitting electric power from a power supply device in a contactless manner, when there is a possibility of excessive AC power generation, A technique for stopping power transmission from the home is disclosed. That is, in such a charging system, when not all of the power transmitted from the power supply device is consumed on the vehicle side, the transmitted power is reflected on the vehicle side, the power is amplified, and the maximum saturation power (critical point) Oscillation phenomenon that reaches Therefore, in Patent Document 2, when the reflected power detected by the reflected power detection unit exceeds the predetermined level, the reflected power detection unit that detects the AC power reflected by the power receiving resonance coil is provided in the power feeding device. The power supply is stopped.

Japanese Patent Laid-Open No. 11-46157 JP 2010-68634 A

  However, the technique disclosed in Patent Document 2 does not provide a countermeasure for stopping power transmission from the power transmission side when charging of the secondary battery is completed. That is, the charging system of Patent Document 2 stops supplying AC power when the reflected power exceeds a predetermined level, regardless of completion of charging, and the reflected power is superimposed on the transmission power to make the AC power abnormal. It is intended to prevent the increase. Therefore, the intention of making the reflected power level correspond to the completion of charging of the secondary battery is not disclosed.

  In addition, since the reflected power is generated due to mismatch between the power transmission side impedance and the power receiving side impedance, the level of the reflected power varies greatly depending on the impedance matching state at the start of charging. That is, the value of the reflected power at the time of completion of charging varies every time the battery is charged, so it is difficult to make the level of the reflected power correspond to the completion of charging. Therefore, even if the supply of AC power is stopped when the reflected power exceeds a predetermined level, the power transmission from the power transmission side cannot be stopped appropriately according to the completion of charging.

  The present invention has been made in view of such circumstances, and appropriately detects the charging state of the secondary battery in the power receiving side device on the power transmission side without providing communication means on the power transmission side and the power receiving side. An object of the present invention is to provide a resonance type wireless charging apparatus capable of automatically stopping power transmission when charging is completed.

  In order to solve the above problems, as a basic configuration of the resonance type wireless charging apparatus of the present invention, the power output from the power transmission apparatus is transmitted to the power reception apparatus by magnetic resonance without contact and connected to the power reception apparatus. The power transmission device is configured to charge a battery, the high-frequency power supply unit that generates AC power, the primary coil for power transmission that transmits the AC power, and the reflected power that is reflected by the primary coil for power transmission. A reflected power detection unit for detecting; and a power supply controller for controlling generation of the AC power by the high-frequency power supply unit, wherein the power reception device receives a secondary coil for receiving AC power transmitted from the power transmission device; , Using a rectifier that rectifies the received AC power and a DC power output from the rectifier, the secondary battery is subjected to constant current charging that causes a constant charging current to flow. After, and a charger for performing constant-voltage charging which controls the charging current so that the battery voltage is constant.

  In the resonance type wireless charging apparatus of the first configuration of the present invention, in addition to the basic configuration, the power supply controller detects the time change rate of the reflected power and is detected in the constant voltage charging process. Control is performed so that transmission of the AC power is stopped when the time change rate becomes equal to or lower than a lower threshold RCL set in correspondence with a predetermined charging rate.

  The resonance type wireless charging device of the second configuration of the present invention is characterized in that, in addition to the basic configuration, the power transmission device stores a charging time Tp required to reach a predetermined charging rate from the start of the constant voltage charging. The power supply controller detects a time change rate of the reflected power detected during the constant voltage charging process by the charger, and sets the time change rate when the constant current charging is switched to the constant voltage charging. Control is performed to stop transmission of the AC power when the charging time Tp elapses from the time when the time change rate exceeds a high threshold RCH set corresponding to the magnitude.

  According to the resonance type wireless charging apparatus having the above-described configuration, the state of charge of the secondary battery in the power receiving side device can be appropriately detected on the power transmission side based on the time change rate of the reflected power in the constant voltage charging process. Without providing communication means on the power transmission side and the power reception side, it is possible to automatically stop power transmission when charging is completed with a simple configuration.

The block diagram which shows the structure of the resonance type wireless charging device in embodiment of this invention Time chart for explaining the operation of the resonance type wireless charging apparatus according to the first embodiment The figure which shows the relationship between the charging rate of the secondary battery in the constant voltage charge state of the resonance type wireless charging apparatus and the time change rate of the reflected power Flow chart showing an example of operation of the resonance type wireless charging apparatus FIG. 9 is a flowchart showing an example of the operation of the resonance type wireless charging apparatus according to the second embodiment.

  The resonance type wireless charging apparatus of the present invention can take the following modes based on the above configuration.

  That is, in the resonance type wireless charging apparatus of the first configuration, the power controller is set in accordance with the magnitude of the time change rate when the time change rate is switched from the constant current charge to the constant voltage charge. After exceeding the high threshold value RCH, it can be configured to determine whether or not the time change rate has become equal to or less than the low threshold value RCL.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Embodiment 1>
FIG. 1 shows the overall configuration of the resonant wireless charging apparatus according to the first embodiment. This resonance type wireless charging device is configured to transmit electric power output from the power transmission device 1 to the power reception device 2 by magnetic resonance without contact, and to charge the secondary battery 15 connected to the power reception device 2. ing.

  The power transmission device 1 includes a power transmission primary coil 3 and a power transmission excitation coil 4 electromagnetically coupled to the power transmission primary coil 3. The power receiving device 2 includes a power receiving secondary coil 5 and a power receiving excitation coil 6 electromagnetically coupled to the power receiving secondary coil 5. The electric power transmitted by the primary coil 3 for power transmission is received by the secondary coil 5 for power reception in a non-contact manner by magnetic field resonance.

  A high frequency power source (AC power source) 7 is connected to the power transmission excitation coil 4 of the power transmission device 1 via a directional coupler 8 to supply high frequency power (AC power). The high frequency power source 7 outputs high frequency power of, for example, about several MHz to several tens of MHz. The high frequency power output from the high frequency power source is transmitted to the primary coil 3 for power transmission by electromagnetic induction via the excitation coil 4 for power transmission. A capacitor C is connected to the primary coil 3 for power transmission, and is set to resonate at a specific resonance frequency. A reflected power detector 9 is also connected to the power transmission excitation coil 4 via a directional coupler 8. The reflected power detection unit 9 detects reflected power in which AC power is reflected by the primary coil 3 for power transmission.

  A power supply controller 10 is connected to the high frequency power supply 7, and generation of high frequency power by the high frequency power supply 7 is turned on / off by a power transmission on / off signal sent from the power supply controller 10. The power controller 10 generates a power transmission on / off signal based on the reflected power value data detected by the reflected power detection unit 9. A charge on / off switch 11 is also connected to the power controller 10. The input of the power transmission on / off signal to the high frequency power supply 7 can also be performed by operating the charging on / off switch 11. Thereby, the user can operate the start / stop of power transmission.

  The power receiving secondary coil 5 of the power receiving device 2 is arranged in a non-contact manner apart from the power transmitting primary coil 3 and receives AC power from the power transmitting primary coil 3 by magnetic field resonance. A capacitor C is also connected to the power receiving secondary coil 5, and a resonance frequency equivalent to the resonance frequency set in the power transmitting primary coil 3 is set.

  A rectifier 12 is connected to the power receiving excitation coil 6, and the AC power transmitted from the power receiving secondary coil 5 to the power receiving excitation coil 6 by electromagnetic induction is rectified by the rectifier 12 to become DC power. A constant voltage controller 13 is connected to the rectifier 12, and the power voltage rectified by the rectifier 12 is converted into a predetermined constant voltage by the constant voltage controller 13. The electric power converted into the predetermined constant voltage is sent to the charger 14, and the charger 14 charges the connected secondary battery 15 with the electric power.

  The charger 14 controls charging so that the secondary battery 15 performs constant current constant voltage charging (CCCV charging). That is, a constant current charging process for supplying a constant charging current to the secondary battery 15 and a constant voltage charging process for controlling the charging current so that the battery voltage of the secondary battery 15 becomes constant after the constant current charging. The charging is controlled so as to include the two-stage charging.

  The feature of the present embodiment is that the power controller 10 generates a power transmission off signal based on the reflected power value data detected by the reflected power detector 9, and the high frequency power from the high frequency power source 7 is generated by the power transmission off signal. It is configured to stop the occurrence. That is, the reflected power reflected by the power transmission primary coil 3 enters the reflected power detection unit 9 through the power transmission excitation coil 4 and the directional coupler 8. The reflected power is measured by the reflected power detector 9, and the measured reflected power value is sent to the power supply controller 10. Based on the reflected power data, the power supply controller 10 recognizes (determines) that charging of the secondary battery 15 has been completed, and inputs a power transmission off signal to the high frequency power supply 7.

  In order for the power supply controller 10 to determine the completion of charging of the secondary battery 15 based on the reflected power data, the time change rate of the reflected power is used. This will be described with reference to the time chart of FIG. In FIG. 2, the horizontal axis indicates the passage of time, the vertical axis from the top, (a) is the charging rate (%) of the secondary battery, (b) is the secondary battery voltage, (c) is the charging current, ( d) shows the reflected power, and (e) shows the time change rate of the reflected power.

  First, when the operator turns on the charging on / off switch 11 (charging start timing shown in FIG. 2), a power transmission on signal is sent from the power controller 10 to the high frequency power source 7, and the power transmission device 1 is output by the output of the high frequency power source 7. Power transmission from is started. When power transmission is started, as described above, power is transmitted to the charger 14 of the power receiving device 2, and charging of the secondary battery 15 is started.

  First, as step (I), as shown in FIG. 2C, constant current charging is performed in which a constant charging current is supplied to the secondary battery 15. During constant current charging, the reflected power detected by the reflected power detection unit 9 in the power transmission device 1 takes a substantially constant value as shown in FIG.

  Here, the reflected power will be briefly described. The reflected power is generated due to a mismatch between the power transmission side impedance and the power reception side impedance (the power reception side impedance includes the coupling state between the power transmission primary coil 3 and the power reception secondary coil 5). If the difference in impedance is small, the reflected power is small. If the difference in impedance is large, the reflected power is large. In the case of constant current charging, since the power transmission side impedance and the power reception side impedance are constant, the impedance matching state (difference between the power transmission side impedance and the power reception side impedance) does not change, and as shown in FIG. Takes a constant value.

  As constant current charging proceeds, the secondary battery voltage increases as shown in FIG. When the secondary battery voltage reaches a predetermined set voltage Vb0, as shown in FIGS. 2 (b) and 2 (c), the charging current is controlled so that the secondary battery voltage becomes constant as step (II). Switch to constant voltage charging. Switching from the constant current charging to the constant voltage charging at the timing when the secondary battery voltage reaches Vb0 is controlled by the charger 14 in the same manner as a known technique.

  In the constant voltage charging state, as the charging proceeds, the internal resistance of the secondary battery 15 increases, so that the charging current decreases as shown in FIG. When the charging current changes, the power receiving side impedance changes accordingly, so the difference between the power transmission side impedance and the power receiving side impedance changes, and the reflected power changes as shown in FIG. The reflected power is detected by the reflected power detection unit 9 in the power transmission device 1, and the detected reflected power data is sent to the power supply controller 10. The power controller 10 obtains the time change rate of the reflected power based on the reflected power data.

  In the constant voltage charging state, the time change rate of the reflected power tends to decrease as shown in FIG. Based on this, the time change rate of the reflected power at which the charging rate is approximately 100% is examined in advance, and a threshold value (low threshold value RCL) corresponding thereto is set. When the time change rate of the reflected power becomes equal to or lower than the lower threshold value RCL, the power supply controller 10 determines that charging is complete and inputs a power transmission off signal to the high frequency power supply 7. Thereby, the high frequency power supply 7 stops power transmission.

  The reason for determining the completion of charging not by the level of reflected power but by the time rate of change of reflected power is because it is difficult to set a threshold for determining completion of charging by the level of reflected power for the following reason.

  That is, in order to set a threshold for the level of reflected power, the relationship between the power transmission side impedance and the power reception side impedance at the start of the charging operation must be reproduced in a constant state. For example, before starting the series of charging operations described above, an operation for matching the power transmission side impedance and the power reception side impedance is performed, and the reflected power in the constant current charging state is suppressed to be relatively low. However, since the accuracy of such prior matching operation is not high, the matching state varies, and the value of the reflected power in the constant current charging state varies with each charging.

  As a result, the value of the reflected power at the time of completion of charging varies every time the battery is charged, and it is impossible to set a threshold value for determining the completion of charging for the reflected power in FIG. Therefore, the time change rate of the reflected power is used. The time change rate of the reflected power in the constant voltage charging state becomes a small value when the charging rate approaches 100%, and the state of the change hardly changes even if the matching state before the start of charging varies. FIG. 3 shows the relationship between the time change rate of the reflected power and the charging rate (ratio) in the constant voltage charging state. Such a relationship diagram is obtained in advance by experiment, and the time change rate of the reflected power at which the charging rate becomes 100% is set as the low threshold RCL for determining that charging is completed.

  As shown in FIG. 3, the time change rate of the reflected power and the charging rate in a constant voltage charging state are in a one-to-one correspondence. Therefore, if these related data are stored in the power transmission device 1, the charging rate can be recognized from the value of the time change rate of the reflected power on the power transmission device 1 side. Further, the lower threshold value RCL does not necessarily correspond to the time change rate of the reflected power at which the charging rate is almost 100%. That is, the low threshold value RCL can be set in correspondence with the desired charging rate, whereby charging can be stopped when the desired charging rate is reached.

  Further, the determination of the completion of charging based on the lower threshold value RCL must be performed in the process of constant voltage charging. This is because, as shown in FIG. 2 (d), the reflected power takes a substantially constant value in the constant current charging process. Therefore, as shown in FIG. This is because it becomes almost zero and is detected to be lower than the lower threshold RCL. Therefore, it is necessary to determine the switching from constant current charging to constant voltage charging by some method. The method is not particularly limited, but for example, the following method can be used.

  That is, the time change rate of the reflected power changes most greatly at the timing when switching from constant current charging to constant voltage charging. Therefore, if the time change rate of the reflected power is monitored on the power transmission device 1 side, the timing at which the power transmission device 1 switches from constant current charging to constant voltage charging can be detected very accurately. In this case, the high threshold value RCH for detecting the timing of switching to constant voltage charging is set separately from the low threshold value RCL used for determining the completion of charging. Then, it is determined that the charging is completed when the time change rate of the reflected power exceeds the high threshold RCH and then becomes equal to or lower than the low threshold RCL.

  The operation of the resonance type wireless charging apparatus having the above configuration will be described with reference to the flowchart of FIG. The left flow in FIG. 4 shows the operation of the power transmission device 1, and the left flow shows the operation of the power reception device 2.

  When the operator turns on the charging on / off switch 11 of the power transmission device 1, a power transmission on signal is sent from the power controller 10 to the high frequency power source 7, and the high frequency power source 7 generates AC power to start feeding (step). S1). Next, the time change rate of the reflected power is detected using the detection output of the reflected power detection unit 9 (step S2), and it is determined whether or not the time change rate exceeds the above-described high threshold RCH (step S3). . If the high threshold RCH is not exceeded (No at Step S3), Steps S2 and S3 are repeated.

  On the other hand, in the power receiving device 2, when the power supply from the high frequency power source 7 is started (step S1), the power from the power transmitting device 1 is received (step S11). Note that the flow from step S1 to step S11 is indicated by a broken line in order to indicate wireless. With the power reception, the constant current charging is started (step S12), and the charger 14 determines whether or not the battery voltage of the secondary battery 15 has reached a predetermined set voltage Vb0 to be switched to the constant voltage charging. (Step S13). If the set voltage Vb0 has not been reached, steps S12 and S13 are repeated.

  When the set voltage Vb0 is reached (step S13, Yes), the implementation of constant voltage charging (step S14) is started, and accordingly, it is determined whether or not the predetermined charging is completed (step S15). Completion of the predetermined charging may be determined by a known method. For example, it can be determined when the charging current is equal to or less than a set threshold value. When the predetermined charging is completed (step S15, Yes), the charging operation is terminated (step S16).

  Further, in the power transmission device 1, it is detected that the rate of change with time exceeds the high threshold RCH (Step S <b> 3, Yes) as constant voltage charging is started in the power receiving device 2 (Step S <b> 14). This does not mean that the start of step S14 is directly detected, but is indirectly detected by a rapid increase in the time change rate of the reflected power as described above.

  As a result of detecting that the time change rate has exceeded the high threshold RCH, the process proceeds to step S4, and the time change rate of the reflected power is detected again using the detection output of the reflected power detection unit 9, and the time change rate is It is determined whether or not the lower threshold value RCL has been reached (step S5). If it is not lower than the lower threshold RCL (step S5, No), steps S4 and S5 are repeated. In this way, it is determined whether or not the time change rate of the reflected power has become equal to or lower than the lower threshold RCL during the constant voltage charging.

  As a result of step S5, if the time change rate becomes equal to or lower than the lower threshold value RCL (step S5, Yes), the power supply from the high frequency power supply 7 is stopped (step S6). As described above, the time change rate of the reflected power becomes equal to or lower than the lower threshold value RCL when the predetermined charging is completed (step S15, Yes), so that the completion of the charging can be appropriately detected.

  As described above, the detection of the time change rate of the reflected power according to the present embodiment can be performed in the power transmission device 1 and it is unnecessary to accurately detect completion of charging without requiring communication with the power reception device 2. It is possible to avoid unnecessary power transmission.

<Embodiment 2>
A resonance type wireless charging apparatus according to Embodiment 2 will be described with reference to the flowchart of FIG. The configuration of the resonance type wireless device in the present embodiment is the same as the configuration of the first embodiment shown in FIG. The difference from the case of the first embodiment is in the control operation by the power supply controller 10. Therefore, in the flowchart of FIG. 5, steps S21 to S22 are replaced with steps S4 to S5 in FIG. Accordingly, the same steps as those in FIG. 4 are denoted by the same step numbers, and the description will not be repeated.

  The feature of this embodiment is to use the following phenomenon related to the time change rate of the reflected power. That is, as described above, by monitoring the rate of change of reflected power over time and detecting that the high threshold RCH has been exceeded, the timing of switching from constant current charging to constant voltage charging can be very accurately determined on the power transmission device 1 side. Can be detected. Therefore, if the charging rate X% at the switching timing is stored in the power transmission device 1 in advance, the timing at which the charging rate X% during the charging operation is achieved can be detected very accurately on the power transmission side. .

  Based on this, the remaining charge rate (100-X)% necessary for setting the charge rate to a desired value, for example, 100%, can also be accurately recognized. Therefore, the charging time Tp necessary for charging the remaining charging rate is set in the power transmission device 1 in advance, and power is transmitted for the charging time Tp from the timing when the detected constant current charging is switched to the constant voltage charging. By stopping power transmission, it is possible to automatically stop power transmission after charging to a charging rate of 100%. Also in the present embodiment, it is not necessary to set the charging rate as a reference for stopping power transmission to 100%. That is, a charging time Tp necessary for charging the remaining charging rate (PX)% required to obtain the desired charging rate P% is set in advance in the power transmission device 1, thereby Charging can be stopped when the charging rate P% is reached.

  In order to execute the above procedure, after it is detected in step S3 of FIG. 5 that the time change rate of the reflected power exceeds the high threshold RCH, the subsequent charging time is measured (step S21). Accordingly, it is determined whether or not the charging time Tp has elapsed (step S22). And when charge time Tp passes (step S22, Yes), generation | occurrence | production of the alternating current power by the high frequency power supply 7 is stopped, and electric power feeding is complete | finished (step S6). In this way, it is possible to accurately detect the completion of charging and avoid unnecessary power transmission without requiring communication with the power receiving device 2.

  As described above, the resonance type wireless charging device of the present invention is a constant current and constant voltage charging for the secondary battery connected to the power receiving device by the power transmitted from the power transmitting device to the power receiving device by magnetic resonance without contact. I do. Then, based on the time change rate of the reflected power detected on the power transmission device side after shifting to constant voltage charging, the power transmission device side determines that charging is complete and stops the generation of AC power by the high-frequency power source. Accordingly, it is possible to appropriately detect the completion of charging of the secondary battery in the power receiving device and avoid waste of power in the power transmitting device without providing communication means on the power transmitting side and the power receiving side.

  The present invention is not limited to the above-described embodiments. For example, the present invention may be modified and embodied as follows.

  In other words, FIG. 1 shows a helical shape in which the electric wire is wound spirally for each of the primary coil 3 for power transmission and the secondary coil 5 for power reception. It is good also as the spiral shape wound by the shape. Further, the outer shape of these coils is not limited to a circle, and may be, for example, a quadrangular or octagonal polygon, or an elliptical shape. Furthermore, the primary coil 3 for power transmission and the secondary coil 5 for power reception have the same size (coil diameter, length, etc.) in FIG. 1, but the sizes of the two may be different.

  In the example of FIG. 1, the capacitor C is connected to the primary coil 3 for power transmission and the secondary coil 5 for power reception. However, only the coil not connected to the capacitor C is used, and the line capacitance of the coil wire You may make it resonate.

  Moreover, although the reflected power from the primary coil 3 for power transmission in the power transmission device 1 is input to the reflected power detection unit 9 via the directional coupler 8 and measured, the directional coupler 8 and the reflected power are shown. Instead of using the power detection unit 9, the reflected power may be directly input to the high frequency power supply 7. In that case, the reflected power is measured in the high frequency power supply 7 and the measurement data is sent to the power supply controller 10. Further, based on the reflected power data, the power supply controller 10 recognizes (determines that the secondary battery 15 has been fully charged) and inputs a power transmission off signal to the high frequency power supply 7.

  According to the resonance type wireless charging apparatus of the present invention, it is possible to stop power transmission from the power transmission apparatus when charging is completed and avoid waste of electric power with a simple configuration. Electric vehicles, industrial equipment, portable It is useful as a device for charging a battery such as an electronic device.

DESCRIPTION OF SYMBOLS 1 Power transmission apparatus 2 Power reception apparatus 3 Primary coil for power transmission 4 Excitation coil for power transmission 5 Secondary coil for power reception 6 Excitation coil for power reception 7 High frequency power supply 8 Directional coupler 9 Reflected power detection part 10 Power supply controller 11 Charging on / off switch 12 Rectifier 13 Constant Voltage Controller 14 Charger 15 Secondary Battery

Claims (3)

In a resonance type wireless charging device that transmits electric power output from a power transmission device to a power reception device by magnetic resonance without contact, and charges a secondary battery connected to the power reception device.
The power transmission device is:
A high-frequency power supply that generates AC power;
A primary coil for power transmission for transmitting the AC power;
A reflected power detector that detects reflected power reflected by the primary coil for power transmission;
A power controller for controlling the generation of the AC power by the high-frequency power unit,
The power receiving device is:
A secondary coil for receiving power that receives AC power transmitted from the power transmission device;
A rectifier that rectifies the received AC power;
Constant voltage charging for controlling the charging current so that the battery voltage becomes constant after performing constant current charging for supplying a constant charging current to the secondary battery using DC power output from the rectifier. With a charger to perform
The power controller detects a time change rate of the reflected power, and the time change rate detected in the constant voltage charging process is equal to or lower than a low threshold RCL set in correspondence with a predetermined charge rate. In this case, the resonance type wireless charging apparatus is controlled so as to stop the transmission of the AC power.   The power supply controller, after the time change rate exceeds a high threshold RCH set corresponding to the magnitude of the time change rate when switching from the constant current charge to the constant voltage charge, the time change rate The resonance type wireless charging apparatus according to claim 1, wherein it is determined whether or not the value is equal to or lower than the lower threshold value RCL. In a resonance type wireless charging device that transmits electric power output from a power transmission device to a power reception device by magnetic resonance without contact, and charges a secondary battery connected to the power reception device.
The power transmission device is:
A high-frequency power supply that generates AC power;
A primary coil for power transmission for transmitting the AC power;
A reflected power detector that detects reflected power reflected by the primary coil for power transmission;
A power controller for controlling the generation of the AC power by the high-frequency power unit,
The power receiving device is:
A secondary coil for receiving power that receives AC power transmitted from the power transmission device;
A rectifier that rectifies the received AC power;
Constant voltage charging for controlling the charging current so that the battery voltage becomes constant after performing constant current charging for supplying a constant charging current to the secondary battery using DC power output from the rectifier. With a charger to perform
In the power transmission device, a charging time Tp required to reach a predetermined charging rate from the start of the constant voltage charging is stored,
The power supply controller detects the time change rate of the reflected power detected during the constant voltage charging process by the charger, and the magnitude of the time change rate when the constant current charging is switched to the constant voltage charging. The resonance type wireless is controlled so as to stop the transmission of the AC power when the charging time Tp elapses from the time when the time change rate exceeds the high threshold RCH set corresponding to Charging device.

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