JP2000166129A - Method and apparatus for reducing stand-by power of noncontact charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce stand-by time power consumption, and additionally to automatically perform non-charging time intermittent operation and charging- time continuous operation on the basis of the magnitude of a primary input current, without bothering a user, by operating a switch device intermittently when charging is not performed or when charging is finished. SOLUTION: A noncontact charger 10 performs charging by connecting a rectifier circuit 18 to a commercial power source 12, connecting a primary power feed coil 22a of an electromagnetic transformer 22 and a switch device 24 to the circuit 18 via a filter capacitor 20, and connecting a battery 36 to the secondary power receiving coil 22b of this transformer 22 through a rectifier circuit, has a current sensor 26 which detects the input current on the primary side of the electromagnetic transformer, and controls switch operation of the switch device 24 causing a control circuit 28 to oscillate intermittently or continuously, on the basis of the relation between the current detected by the sensor 26 and a preset current value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for reducing standby power of a contactless charger, and more particularly to a secondary battery for a power supply mounted on, for example, an assisted bicycle or a portable electronic device such as a mobile phone or an information terminal. The present invention relates to a method and an apparatus for reducing standby power of a non-contact charger for charging a battery (hereinafter simply referred to as a “battery”).

[0002]

2. Description of the Related Art Conventionally, non-contact chargers are not always supplied with commercial power only when used as in contact type chargers, but are often used while always connected to commercial power.
This charger is disclosed, for example, in Japanese Patent Laid-Open No.
02J 7/00], an oscillating circuit and an oscillating coil driven by an oscillating signal from the oscillating circuit are provided in the charging section, and the oscillating coil is electromagnetically coupled to the charged section. An electromagnetic coupling coil and a rectifying circuit for rectifying the electric power induced in the electromagnetic coupling coil are provided so that the battery can be charged without using a charging contact.

For this reason, the oscillation circuit and the like are kept in an operating state even during standby, that is, at the time of non-charging or after the end of charging, and are continuously supplied with power from an AC power supply. Needs to be further reduced.

[0004]

Generally, in this type of charger, an effective means for reducing the power consumption during standby is to stop the charging circuit during standby. In this case, it is necessary to switch between charging and non-charging with a mechanical switch or the like. Further, when the user forgets to turn off the switch, there is a problem that the standby power cannot be reduced.

Further, it is easiest to perform automatic detection during charging and non-charging by monitoring the charging current. However, in a charger using the non-contact method, the secondary side including the charging current is included. It is difficult to detect information. Therefore,
It is necessary to detect the charging current during non-charging on the primary side. Therefore, a method of reducing the switching frequency or reducing the power during standby due to the intermittent operation of switching can be considered.

Accordingly, a main object of the present invention is to automatically and intermittently operate a primary switching power supply of a non-contact charger, thereby reducing standby power during non-charging without requiring troublesome operation. It is an object of the present invention to provide a method and an apparatus for reducing standby power of a non-contact charger which can achieve the following.

[0007]

According to the present invention, a primary power supply coil of an electromagnetic transformer and a switching means are connected to a commercial power supply via a rectifier circuit, and a secondary power receiving coil of the electromagnetic transformer is connected via a rectifier circuit. (A) When the primary input current is less than a set value, the switching means is operated intermittently, and (b) the primary current is more than the set value. A standby power reduction method for a non-contact charger, characterized in that the switching means is operated continuously at the time.

According to the present invention, in the above-described non-contact charger, the current detecting means for detecting the primary input current of the electromagnetic transformer, and the switching means are operated intermittently when the primary current is less than a set value. And a control unit for continuously operating the switching unit when the primary current is equal to or higher than a set value.

[0009]

The primary-side input current is detected by the current detecting means, and when the current is equal to or less than the set value, the switching means is intermittently operated by the control means to suppress power consumption on the charger side during non-charging. As a result, the standby power can be reduced.

[0010]

According to the present invention, the intermittent operation during non-charging reduces power consumption during standby. In addition, since the intermittent operation and the continuous operation of the switching means are automatically performed based on the primary-side input current detected by the current detection means, a reliable operation can be expected without bothering the user.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a schematic circuit configuration of a non-contact charger 10 according to an embodiment of the present invention. The charger 10 includes a charging section 14 connected to a commercial power supply 12 of 100 VAC and a charging section 14 connected to the charging section 14. It has a charged part 16 that is appropriately set.

The charging section 14 includes a rectifying circuit 18 for converting AC of the commercial power supply 12 to DC, a smoothing capacitor 20, and an electromagnetic transformer 2 connected to a DC output terminal of the rectifying circuit 18.
2 primary-side feeding coil 22a and this feeding coil 2a.
The control circuit 28 controls the switching element 24 based on the detection current of the current sensor 26 that detects the primary-side input current and the switching element 24 that controls the energization of 2a.

The charged portion 16 includes a secondary side power receiving coil 22b of the electromagnetic transformer 22 and the power receiving coil 22b.
And a full-charge detection circuit 38 for controlling ON / OFF of the battery 36 and the transistor 34 connected via the rectifier diode 30, the smoothing capacitor 32 and the switching transistor 34. As shown in FIG. 6, the electromagnetic transformer 22 includes an L-shaped primary core 23 and an L-shaped secondary core 25, and the power supply coil 22a is wound around a horizontal piece 23a of the primary core 23 to receive power. The primary core 23 and the secondary core 25 are combined to form a rectangular magnetic path so that the power supply coil 22b is inserted into the hollow portion of the power supply coil 22b.

Here, an outline of the operation of the contactless charger 10 will be described. First, when charging the battery 36, the primary-side input current Iin from the current sensor 26 is controlled by the control circuit 2.
8 or higher than the set current value (charge current value) Iref (Iin ≧
Iref), the control circuit 28 performs continuous oscillation, which will be described later, and the switching element 24 continues the switching operation.

As a result, the alternating current from the commercial power supply 12 is converted to direct current by the rectifier circuit 18, further smoothed by the smoothing capacitor 20, and supplied to the primary side feeding coil 22 a of the electromagnetic transformer 22. Then, a magnetic flux (lines of magnetic force) synchronized with the switching operation of the switching element 24 is generated from the power supply coil 22a, and a voltage is induced in the secondary side power receiving coil 22b of the electromagnetic transformer 22. The voltage is generated by the rectifier diode 30 and the smoothing capacitor 32. After being converted into a DC current by the rectifier circuit configured, the DC current is supplied to the battery 36 via the switching transistor 34. Battery 36
When the charging of the battery has progressed to the full charge, the full charge detection circuit 38
Is activated, the switching transistor 34 is turned off, and charging ends.

When the charging is completed, the primary-side input current Iin detected by the current sensor 26 becomes equal to or less than the set current value Iref (Iin ≦ Iref), and the control circuit 28 performs the intermittent oscillation at a sufficiently low duty ratio and about 25%. Do. As a result, the switching element 24 also intermittently stops its operation (intermittent operation).
2a also stops operating during that time. Therefore, the power consumption of the charging unit 14 can be reduced and the heat generation can be reduced.

Further, even when the charging section 14 is not set and the charged section 16 is not set, the primary input current Iin by the current sensor 26 is equal to or less than the set current value Iref (Iin ≦ Ire
f), the switching element 24 intermittently stops operating (intermittent operation), and the charging unit 14 operates similarly to the end of charging.
Power consumption and heat generation are reduced. For example, conventionally, the power consumption of 4 W of the charging circuit during non-charging can be reduced to about 1/4 of 1 W when the method according to the present invention is implemented. That is, the reduction rate of the power consumption during standby is 75%.

Next, the specific configuration and operation of the control circuit 28 shown in FIG. 2 will be described. The control circuit 28 includes an intermittent oscillation circuit 40 that performs intermittent oscillation based on the input current Iin detected by the current sensor 26, and a PWM control circuit 42 that outputs a gate signal to the switching element 24 by PWM control based on the output of the oscillation circuit 40. Including. The output control voltage Vcnt of the intermittent oscillation circuit 40 is held by an externally connected capacitor Ccnt. PWM control circuit 4
2 compares the smaller of the output control voltage Vcnt of the intermittent oscillation circuit 40 and the smaller of the duty control voltage Vr based on the reference voltage 44 with the voltage Vtri of the triangular wave generator 46 by the voltage comparator 48, and the output control voltage Vcnt is the voltage of the triangular wave Vtr
If it becomes smaller than the minimum value of i, the PWM control circuit 42 stops outputting the gate signal to the switching element 24 (see FIG. 4).

As shown in FIG. 3, the intermittent oscillation circuit 40 includes a primary-side input current Iin detected by the current sensor 26.
58 to a voltage, an input current smoothing circuit 50 composed of a resistor and a capacitor, and charge ON / OFF control transistors 52 and 54. The winding 56
Is a voltage generated by the operation of the charging main circuit, and the diode 6
0 and charge ON / O after smoothing by the smoothing capacitor 62
The power is supplied to the collectors and bases of the FF control transistors 52 and 54 and serves as a drive power supply for each transistor.

Next, the operation of the intermittent oscillation circuit 40 will be described. A) When the input current Iin is small (at the time of non-charging or at the end of charging) In this case, since the transistor 52 is off, the transistor 54 is turned on by the voltage Vs of the driving power supply and is connected to the output terminal of the intermittent oscillation circuit 40. Lower the potential of Ccnt. At this time, since the charging main circuit has stopped operating, no voltage is generated in the winding 56, the potential of the driving power supply voltage Vs is reduced by the resistor Rs, and the transistor 54 is turned off.
Becomes Then, the capacitor Ccnt is charged by the constant current source I, the charging main circuit is turned on, a voltage is generated in the driving power supply Vs, and the transistor 54 is turned on again. Thereafter, this operation is repeated at a timing determined by the CR constant of the resistor 64 connected to the collector of the transistor 54 and the capacitor Ccnt. Accordingly, the switching element 24 also intermittently stops operating, and the charging unit 14 also performs intermittent operation. Thereby, the power consumption of the charging circuit during standby can be reduced.

B) When the input current Iin is large (at the time of charging) In this case, since the charge ON / OFF control transistor 52 is ON, the transistor 54 is OFF and the capacitor Ccnt connected to the output terminal of the intermittent oscillation circuit 40 is turned off. The potential is stably held, and the PWM control circuit 42 continuously outputs a gate signal to the switching element 24.
As a result, the switching element 24 continues the switching operation, and the charged portion 16 can charge the battery 36. Note that the PWM control circuit 42 may be configured by a control IC.

As described above, in the non-contact charger, the charging and non-charging of the battery can be performed by controlling the switching element by continuously or intermittently oscillating the control circuit based on the magnitude of the input current Iin. it can.
In addition, standby power during non-charging can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a schematic circuit configuration of a contactless charger showing one embodiment of the present invention.

FIG. 2 is a block diagram of a control circuit shown in FIG.

FIG. 3 is a circuit configuration diagram of an embodiment of the intermittent oscillation circuit shown in FIG. 2;

4 is a timing chart of an input waveform and an output waveform of the PWM control circuit shown in FIG.

FIG. 5 is a timing chart showing a change in an input current waveform during charging and non-charging in one embodiment of the present invention.

FIG. 6 is an illustrative view showing a disassembled state of the electromagnetic transformer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Non-contact charger 12 ... Commercial power supply 14 ... Charging part 16 ... Non-charging part 18 ... Rectifier circuit 20 ... Smoothing capacitor 22 ... Electromagnetic transformer 22a ... Primary side power feeding coil 22b ... Secondary side power receiving coil 24 ... Switching element (Transistor) 26 Current sensor 28 Control circuit 34 Switching transistor 36 Battery 38 Full charge detection circuit

Claims (5)

[Claims] A primary power supply coil for an electromagnetic transformer and a switching means are connected to a commercial power supply via a rectifier circuit, and a battery is connected to a secondary power receiving coil of the electromagnetic transformer via a rectifier circuit for charging. (A) when the primary side input current is less than a set value, the switching means is operated intermittently; and (b) when the primary side current is more than a set value, the switching means is A standby power reducing method for a non-contact charger, wherein the standby power is continuously operated. 2. A secondary power supply coil of an electromagnetic transformer and a switching means are connected to a commercial power supply via a rectifier circuit, and a battery is connected to a secondary power receiving coil of the electromagnetic transformer via a rectifier circuit for charging. A non-contact charger for performing current detection means for detecting a primary-side input current of the electromagnetic transformer, and further, when the primary-side current is equal to or less than a set value, intermittently operating the switching means; When is greater than or equal to a set value, comprising a control means to operate the switching means continuously,
Standby power reduction device for non-contact charger. 3. The apparatus for reducing standby power of a contactless charger according to claim 2, wherein said current detecting means includes a current detecting resistor provided on a primary side of said electromagnetic transformer. 4. The apparatus for reducing standby power of a contactless charger according to claim 2, wherein said control means includes an intermittent oscillation circuit. 5. The apparatus for reducing standby power of a contactless charger according to claim 2, wherein said switching means includes a transistor connected to said power supply coil.