JPH1198704A - Charging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain superior output characteristics of a charging device by a method wherein, when a charging object apparatus having a secondary battery and a secondary coil is attached to a charging stand in which a primary coil excited by an AC current has been incorporated, the attachment mode is contrived. SOLUTION: A charging device has a charging stand 1, in which a primary coil 4 excited by an AC current is incorporated and to which a charging object apparatus 2 having a secondary battery 5 and a secondary coil 6, is attached. In the primary coil 4 and the secondary coil 6 coupled electromagnetically with each other for charging the secondary battery 5, the primary coil 4 has an approximately elliptical shape. The charging object apparatus 2 is so attached to the charging stand 1 as to be approximately in parallel with the direction of the short diameter of the primary coil 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for charging a secondary battery and a secondary coil mounted on a charging stand having a primary coil which is excited by an alternating current. The present invention relates to a charging device that charges the secondary battery by electromagnetically coupling with a coil.

[0002]

2. Description of the Related Art In a device to be charged, such as a battery pack or a portable electric device (an electric razor, a mobile phone, or the like) having a built-in secondary battery, the battery is usually exposed to the outside of the device to charge the secondary battery. Charging terminal. The charging terminal exposed to the outside as described above is exposed to an extremely dirty environment, and may cause poor contact when mounted on a charging stand.

[0003] When a device to be charged is carried in a pocket or a bag, a metal product or a metal chain put in the pocket or the like comes into contact with a charging terminal exposed outside, so that the secondary battery is removed. There is a risk of short circuit.

In order to solve such a problem, a device to be charged having a secondary battery and a secondary coil is mounted on a charging stand having a primary coil which is excited by an alternating current, and the primary coil is connected to the charging device. A non-contact charging device for charging a secondary battery by electromagnetically coupling with a secondary coil has already been developed (see Japanese Patent Application Laid-Open No. 7-39078).

[0005]

What is important in such a non-contact charging device is to improve the electromagnetic coupling between the primary coil and the secondary coil, and to reduce the electric power generated by the primary coil by two.
It is to transmit to the next coil efficiently.

Accordingly, an object of the present invention is to mount a device to be charged having a secondary battery and a secondary coil on a charging stand containing a primary coil which is excited by an alternating current. To obtain excellent output characteristics.

[0007]

According to the present invention, a device to be charged having a secondary battery and a secondary coil is mounted on a charging stand containing a primary coil excited by an alternating current, and And a charging device that charges the secondary battery by electromagnetically coupling the secondary coil with the secondary coil, wherein the primary coil has a substantially elliptical shape, and the device to be charged has a short radial direction of the primary coil. It is characterized by being attached to the charging stand so as to be substantially parallel.

[0008]

FIG. 1 shows an embodiment of the present invention. The charging stand 1 has a recess 1A for mounting the portable electric device 3 on which the battery pack 2 is mounted in a fixed position. Recess 1A
The primary coil 4 is disposed on the inner surface of the side portion of the primary coil. The primary coil 4 is formed in an oval shape having a ferrite core at the center thereof, and the central axis is set in the left-right direction of the drawing and the short radius direction of the oval is set as the vertical direction of the drawing. I have.

The battery pack 2 is detachably mounted on the electric equipment 3 and supplies electric power to the electric equipment 3. Battery pack 2
Has a rectangular box-shaped plastic case in which a rectangular secondary battery 5 made of a lithium ion battery is built in, and a secondary coil 6 is disposed below the secondary battery 5 on the bottom surface of the case. I have. The secondary coil 6 has a rod-shaped ferrite core at the center thereof, and has a central axis extending in the lateral direction of the secondary battery 5, that is, in the horizontal direction of the drawing.

In this configuration, the electric device 3 is connected to the recess 1
A, the battery pack 2 has its height direction (vertical direction in the drawing) substantially parallel to the short radius direction of the primary coil 4 and the center axis of the secondary coil 6 is set at the center of the primary coil 4. It is attached to the charging stand so that it matches the axis. Thus,
The primary coil 4 and the secondary coil 6 are electromagnetically coupled.

FIG. 2 shows an embodiment of the electric circuit. The charging stand 1 includes a power supply circuit 10. The power supply circuit 10 includes a rectifier circuit 11 that converts an input AC of a commercial power supply into DC by a diode and converts the DC into smooth DC by a smoothing capacitor, and an FE connected in series with the primary coil 4.
A switching element 12 made of T and an oscillation circuit 13 for switching the switching element 12 on and off are provided.

The oscillation circuit 13 has a frequency of 50 kHz to 500 kHz.
The switching element 12 is switched on and off at a frequency of z, preferably 100 kHz to 200 kHz. The switching element 12 switches the DC output from the rectifier circuit 11 to excite the primary coil 4 with an AC.

The battery pack 2 includes a control circuit 20 for controlling the charging of the secondary battery 5 by converting the AC output of the secondary coil 6 to a direct current, and a protection circuit 21 for preventing the secondary battery 5 from being overcharged.
And a control unit 27.

The control circuit 20 is connected between the output of the rectifier circuit 22 and the secondary battery 5 and a rectifier circuit 22 for converting an alternating current induced by the secondary coil 6 to a direct current. A charge control unit 23 that controls the state of charge of the battery 5, an arithmetic circuit 24 that controls the charge control unit 23, a current detection unit 25 that detects the charge current of the secondary battery 5 and inputs the current to the arithmetic circuit 24, A voltage detection unit 26 that detects a battery voltage and inputs the battery voltage to the arithmetic circuit 24.

The charge control unit 23 controls the output of the rectifier circuit 22 to a voltage and a current that are optimal for charging the secondary battery 5, and stops charging when the secondary battery 5 is fully charged. To this end, the charging control unit 23 includes a constant voltage / constant current circuit and a switching element for stopping charging.

The arithmetic circuit 24 detects a charging current and a voltage of the secondary battery, and controls a switching element of the charging control unit 23. The arithmetic circuit 24 controls the charge control unit 23 until the secondary battery 5 is fully charged, and stops charging when the secondary battery 5 is fully charged.

When the protection circuit 21 detects that the battery voltage of the secondary battery 5 has become higher than the set voltage, the control circuit 27
Is turned off to stop charging. Further, the protection circuit 21 may detect a charging current and stop charging when an overcurrent flows.

In this embodiment, when the electric device 3 is mounted in the recess 1A, the height direction of the battery pack 2 (ie, the vertical direction in FIG. 1) is substantially parallel to the short radius direction of the primary coil 4. In addition, the central axis of the secondary coil 6 of the battery pack 2 matches the central axis of the primary coil 4. Thereby, the primary coil 4 and the secondary coil 6 are electromagnetically coupled efficiently.

FIG. 3 shows the primary coil 4 as shown in FIG.
5 shows the results of measuring the voltage-current characteristics of the secondary coil 6 when the battery packs 2 are arranged in various positional relations. Specifically, the battery pack 2 is arranged so that the height direction is substantially parallel to the short radius direction of the primary coil 4 (shown by a solid line in FIG. 4), and the center axis of the secondary coil 6 is 4
(Point A) and when the central axis of the secondary coil 6 is arranged on the winding of the primary coil 4 (point C).
, The voltage-current characteristics were measured.

Further, as a comparative example, the battery pack 2 is arranged so that the height and width directions are substantially parallel to the major radius direction of the primary coil 4 (indicated by broken lines in FIG. 4). When the axis is aligned with the central axis of the primary coil 4 (dot) and 2
When the central axis of the secondary coil 6 was arranged on the winding of the primary coil 4 (point), the voltage-current characteristics were measured.

The voltage-current characteristics were measured under the following conditions. The battery pack 2 has a thickness × width × height of 8.7 mm × 28.
A rectangular secondary battery 5 measuring 8.1 mm × 22 mm × 48 mm in a thickness × width × height was used in a plastic case of mm × 52 mm. The secondary coil 6 has a thickness × width × height of 5 mm × 19 mm
A rectangular pillar type ferrite core having a size of 3.7 mm was disposed at the center, and a coil having 25 turns was used. The primary coil 4 used was one in which a long disk-shaped ferrite core was disposed at the center and the coil was wound 242 so that a short radius × a long radius was 20 mm × 28 mm. The primary coil 4 has a DC voltage of 141 V and a current of 20 V.
mA was applied by switching at a frequency of about 120 kHz.

As is apparent from these figures, when the center axis of the secondary coil 6 coincides with the center axis of the primary coil 4 (A
Point and point) and the case where the central axis of the secondary coil 6 is located on the winding of the primary coil 4 (point C and point), the height direction of the battery pack 2 is shorter than that of the primary coil 4. When the battery is arranged so as to be substantially parallel to the radial direction, the battery pack 2
It is clear that the output characteristics are better as compared with the case where the height width direction is arranged substantially parallel to the major radius direction of the primary coil 4.

In particular, when the secondary battery 5 is a lithium ion battery as in this embodiment, the output voltage required to charge the secondary battery 5 needs to be between 4.1 V and 5.0 V. The difference in the output current between the present embodiment and the comparative example in the range is remarkable.

[0024]

According to the present invention, a device to be charged having a secondary battery and a secondary coil is mounted on a charging stand having a primary coil which is excited by an alternating current, and the primary coil and the secondary coil are mounted. In the charging device for charging the secondary battery by electromagnetic coupling, the primary coil has a substantially elliptical shape, and the device to be charged is substantially parallel to a minor radius direction of the primary coil. In addition, since the battery is mounted on the charging stand, excellent output characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing one embodiment of the present invention.

FIG. 3 is a graph showing voltage-current characteristics of a secondary coil.

FIG. 4 is a plan view showing a positional relationship between a primary coil and a secondary coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Charge stand 2 Pack battery 3 Portable equipment 4 Primary coil 5 Secondary battery 6 Secondary coil

Claims (3)

[Claims] 1. A device to be charged including a secondary battery and a secondary coil is mounted on a charging stand containing a primary coil excited by an alternating current, and the primary coil and the secondary coil are electromagnetically connected. In the charging device for charging the secondary battery by coupling, the primary coil has a substantially elliptical shape, and the device to be charged is substantially parallel to a minor radius direction of the primary coil. A charging device, which is mounted on a charging stand. 2. The charging device according to claim 1, wherein the device to be charged is mounted on the charging stand such that a central axis of the secondary coil coincides with a central axis of the primary coil. . 3. A rectangular charging device having a secondary battery and a secondary coil is mounted on a charging stand having a substantially elliptical primary coil which is excited by an alternating current, and A charging device for charging the secondary battery by electromagnetically coupling a coil and the secondary coil, wherein the device to be charged has a narrow surface substantially parallel to a short radius direction of the primary coil. The charging device is mounted on the charging stand.