JPH05300662A - Charger - Google Patents

Abstract

PURPOSE:To see that it does not generate an eddy current even if a conductor is placed by mistake by suppressing the power loss under no-load. CONSTITUTION:A microcomputer 3 detects the oscillated frequency on charger side through an auxiliary winding L4 and an F-V converting circuit 2. When the detected frequency is above the preset frequency, the microcomputer 3 turns on or turns off a transistor Q1 so as to stop the oscillation of a field-effect transistor FET1 intermittently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic induction type charging device for charging a storage battery without contact.

[0002]

2. Description of the Related Art In recent years, a non-contact type charging device has no problems such as rust and electrolytic corrosion of the contact, and has a better water contact than the contact type in which the output terminal to the secondary side is connected to the connection terminal of the load device. It has become popular because it has the merit of being able to wash the mounting part with water for products.

FIG. 8 is an explanatory view schematically showing a conventional non-contact type charging device. FIG. 9 is a circuit diagram of the charging device. The charger 21 supplies electric power to the load device 22 without contact. The core 23 of the transformer 25 is the charger 21.
And load device 22 are divided into a primary side and a secondary side. The primary side is a primary winding L21 and the feedback winding L23 is for self-excited oscillation. The secondary side is an output winding. It consists of L22.

The DC power supply 24 lowers the voltage of the AC power supply or the like to a low voltage, rectifies and smoothes it, and outputs it to the primary winding L21.
It is composed of a transformer and a diode. Primary winding L
21 is a field effect transistor FET for switching
21 is connected to the drain, and its source is DC power supply 24
Is connected to the negative electrode of. The capacitor C22 is for resonance and is connected in parallel between the drain and source of the field effect transistor FET21. Then, the current flowing into the primary winding L21 is switched by turning on / off the field effect transistor FET21, whereby a voltage is induced in the feedback winding L23 and the secondary winding L22, and the load from the secondary winding L22. A charging current is supplied to the storage battery in the circuit 26.

A starting resistor R21 and a capacitor C21 are connected in series between both poles of the DC power source 24. The connection point between the starting resistor R21 and the capacitor C21 is connected to the field effect transistor FET21 via the feedback winding L23.
Of the field effect transistor FE, the diode D21 is connected in series in this direction through the resistor R22 in the forward direction while being connected to the gate of the field effect transistor FE.
It is connected to the drain of T21.

The operation of the conventional charging device configured as described above will be described. When the DC power supply 24 is turned on,
The capacitor C21 is charged through the starting resistor R21 and the voltage of the capacitor C21 rises, and this voltage is applied to the gate of the field effect transistor FET21 through the feedback winding L23. When this applied voltage reaches the ON voltage of the field effect transistor FET21, the field effect transistor FET21 is turned on, a current flows through the primary winding L21, feedback is applied from the feedback winding L23, and the field effect transistor FET21 is turned on.・ Repeat OFF to start oscillation.

Here, the field effect transistor FET21
When the drain voltage of the capacitor C21 is lower than the voltage of the capacitor C21, the charge of the capacitor C21 passes through the resistor R22, the diode D21, and the field effect transistor FET21.
Is discharged. For this reason, the voltage of the capacitor C21 drops and becomes lower than the on-voltage, and the on-time of the field effect transistor FET21 is shortened.

On the other hand, when the above-mentioned on-time is shortened, the time for discharging the electric charge of the capacitor C21 is reduced, so that the voltage of the capacitor C21 is increased. That is, negative feedback is applied in the direction in which the oscillation frequency is stabilized.

As described above, by separating the primary winding L21 of the oscillating transformer 25 into the charger 21 side and the secondary winding L22 into the load device 22 side, the gap and the like of the transformer 25 change. Even in this case, the self-excited oscillation operation can always be stably performed in the optimum state, and the electric power can be efficiently transmitted to the load device side without using the contact point.

[0010]

However, in the above-mentioned conventional charging device, even if the load device is not mounted, stable oscillation continues, resulting in a large power loss. Further, if a conductor is erroneously placed on the charger 21 instead of the load device, magnetic flux will pass through the conductor, and eddy current will be generated to heat the conductor.

On the other hand, an example of a circuit diagram of a conventional contact type charging device is shown in FIG. This connects to the storage battery in the load device 22 via the contacts 28 and 29. In this method, when there is no load, the voltage across the secondary winding L22 becomes high and exceeds the Zener voltage of the Zener diode ZD21, so that the light emitting element that constitutes the photocoupler PC21 receives a current through the resistor R23 for current limiting. Is supplied to turn on the phototransistor of the photocoupler PC21. As a result, the field effect transistor FET2
The output signal from the drive circuit 27 for controlling the oscillation of No. 1 is reset and the switching operation is stopped.

However, when this method is applied to a non-contact type charging device, a signal for discriminating a state such as a no-load state is used.
Feedback from the secondary side to the primary side is impossible because the load device 22 side includes the secondary winding L22 and the like.

The present invention has been made in view of the above-mentioned problems, and suppresses power loss when there is no load, does not generate eddy current even when a conductor is placed, and is a highly safe contactless charging device. The purpose is to provide.

[0014]

In order to achieve the above-mentioned object, the present invention provides an oscillation transformer in which a load device having a storage battery connected to a secondary winding of the oscillation transformer can be attached and detached. A charger having a primary winding, which is capable of supplying an output from the charger to the load device by mounting, detecting for detecting an oscillation frequency in a primary winding of an oscillation transformer of the charger. Means and output control means for reducing the output of the charger when the detected oscillation frequency is equal to or higher than a preset frequency (claim 1).

Further, the output control means intermittently drives the oscillation of the charger when the detected oscillation frequency is equal to or higher than a preset frequency (claim 2).

Further, the output control means is composed of frequency switching means for decreasing the oscillation frequency of the charger when the detected oscillation frequency is equal to or higher than a preset frequency (claim 3).

[0017]

According to the present invention, when the charger is powered on and the load device is mounted, the primary winding of the charger oscillates and a voltage is induced in the secondary winding to cause the storage battery to operate. Charging current is supplied. And when the oscillation frequency in the charger is equal to or higher than the preset frequency, that is, in the no-load state,
The output of the charger is reduced compared to the normal output.

According to the second aspect of the invention, when it is detected that the oscillation frequency of the charger is equal to or higher than the preset frequency, the oscillation of the charger is driven intermittently. As a result, the output of the charger is reduced.

According to the third aspect of the invention, when it is detected that the oscillation frequency of the charger is equal to or higher than the preset frequency, the oscillation frequency of the charger is compared with the normal frequency. Then, the frequency is switched to a low frequency, and the output of the charger is reduced.

[0020]

1 is a circuit diagram of a charger side showing a first embodiment of a charging device according to the present invention. Note that the load device side has a built-in storage battery connected to the secondary winding of the oscillation transformer and has the same configuration as the conventional configuration, and therefore description thereof will be omitted. And
When the load device is mounted on the charger side, an oscillation transformer is configured.

The DC power supply 1 is a device for stepping down the AC power supply or the like to a low voltage, rectifying and smoothing it, and outputting it to the primary winding L1, and is composed of a transformer, a diode and the like. The core on the charger side, which constitutes an oscillation transformer (not shown), is the primary winding L1,
It is composed of a feedback winding L3 and an auxiliary winding L4. Primary winding L1
Is connected to the drain of the field effect transistor FET1 for switching, and its source is connected to the negative electrode of the DC power supply 1. The capacitor C2 is for resonance and is connected in parallel between the drain and source of the field effect transistor FET1. Then, the current flowing into the primary winding L1 is switched by turning on / off the field effect transistor FET1, whereby a voltage is induced in the feedback winding L3 and a secondary winding forming an oscillation transformer (not shown). It is like this.

A starting resistor R1 and a capacitor C1 are connected in series between both poles of the DC power supply 1. The connection point between the starting resistor R1 and the capacitor C1 is connected to the gate of the field effect transistor FET1 via the feedback winding L3, and the diode D1 is connected in series in this direction in the forward direction via the resistor R2. Is connected to the drain of the field effect transistor FET1.

Further, a resistor R5 is connected to the positive electrode of the DC power source 1.
The light emitting diode D2 is connected in series in this direction in the forward direction via the, and the cathode of the light emitting diode D2 is connected to the collector of the transistor Q2 described later, and the transistor Q2 is connected.
The second emitter is grounded.

The auxiliary winding L4 is for detecting the oscillation frequency of the charger. The FV conversion circuit 2 converts a voltage value corresponding to a frequency and outputs the voltage value. The frequency signal is input through the auxiliary winding L4 connected to the source of the field effect transistor FET1 and the output voltage is a microcomputer. 3 is input to the input terminal 31.

The microcomputer 3 controls the operation of the charger. Its output terminal 32 is connected to the base of the transistor Q1 via a current limiting resistor R3, and its output terminal 33 is connected to a current limiting resistor R4. Each is connected to the base of Q2. Then, on / off of the transistors Q1 and Q2 is controlled according to the voltage level input from the F-V conversion circuit 2.

The collector of the transistor Q1 is the gate of the field effect transistor FET1 and the emitter is the DC power supply 1
The field effect transistor FET1 is turned off by being turned on. The transistor Q2 controls turning on / off of the light emitting diode D2 by turning on / off the transistor Q2.

FIG. 2 is a diagram showing an oscillation waveform on the charger side.
(A) shows the case of no load without a load device attached,
(B) shows the case where the load device is mounted, and (c) shows the case where the conductor is placed abnormally. FIG. 3 is a characteristic diagram showing the relationship between the load state and the inductance.

The oscillation frequency of the charger is determined by f = 1 / {2π√ (LC)}, where L is the inductance of the primary winding L1 and C is the capacitance of the capacitor C2.

When the charger is in the no-load state, the inductance of the primary winding L1 is small as shown at point A in FIG.
It oscillates with a waveform (high frequency) as shown in FIG.

Next, when the load device is attached, the line B in FIG.
As indicated by the dot, the inductance of the primary winding L1 increases, so the oscillation frequency decreases, and oscillation occurs with the waveform shown in FIG. 2 (b).

If a conductor such as a 10-yen coin is erroneously placed on the core (not shown) around which the primary winding of the charger is wound,
Since the inductance of the primary winding L1 is further increased as indicated by point C in FIG. 3, oscillation occurs with a waveform as shown in FIG.

Next, the operation of the charging device configured as described above will be described. FIG. 4 is a flowchart showing the operation of the charging device. FIG. 5 shows an example of the output waveform of the output terminal 32 of the microcomputer 3 when the step S3 is passed.

When the DC power supply 1 is turned on, first, the oscillation frequency is detected (step S1), and the detected frequency f is compared with a preset no-load frequency f ₀ (step S2), f If it is not f ₀ , there is no load, so that an “H” level signal is output from the output terminal 32 and the transistor Q is output.
When 1 is turned on and a certain time has passed (step S
3), go to step S6.

On the other hand, if f <f ₀ in step S2, the frequency f is compared with the frequency fs when a preset conductor is placed (step S4). Since it is placed, proceed to step S3,
On the other hand, if f> fs, since the load device is attached, the output terminal 33 outputs a signal at the “H” level to turn on the transistor Q2 to turn on the light emitting diode D2 (step S5), and the output terminal When the signal of level'L 'is output from 32 to turn off the transistor Q1 and a certain period of time elapses (step S6), the process returns to step S1 and the above operation is repeated.

As described above, in the unloaded state or the state in which the conductor is placed, the voltage having the waveform as shown in FIG. 5 is output from the output terminal 32. Also, the presence or absence of a load can be detected only on the primary side without feeding back a signal from the secondary side. When the load device is mounted, the light emitting diode D2 is turned on to mount the load device. Can be displayed.

With the above operation, the power consumption can be suppressed by intermittently oscillating in the no-load state. Further, even if the conductor is placed, the loss due to the eddy current or the like can be suppressed.

Next, a second embodiment of the charging device according to the present invention will be described with reference to FIG. FIG. 6 is a circuit diagram on the charger side showing a second embodiment of the charging device according to the present invention. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, instead of the primary winding L1,
Two types of primary windings L11 and L12 are provided so that they can be switched. The primary winding L12 is the primary winding L
It has a normal inductance equal to 1, and the inductance of the primary winding L11 is set to L11> L12 by increasing the number of coil turns. Further, instead of the light emitting diode D2, the coil part of the relay 4 is connected, and the contact part of the relay 4 is provided between the positive electrode of the DC power supply 1 and the primary winding. That is, the common contact C of the relay 4 is connected to the positive electrode of the DC power supply 1, the primary winding L11 is connected to the contact NC, and the primary winding L12 is connected to the contact NO.

Next, the operation of the second embodiment will be described. When it is detected that there is no load or a conductor is placed, the output terminal 33 outputs an'L 'level signal, and the contact of the relay 4 is on the side of the primary winding L11 as shown in FIG. It remains connected to the contact NC of.

On the other hand, when it is detected that the load device is attached, an "H" level signal is output from the output terminal 33, the relay 4 is activated, and the connection is made from the contact NC to the primary winding L1.
Switch to the 2nd contact NO.

In this way, by switching the primary winding to be connected depending on the load condition, oscillation is performed at the normal frequency only when the load device is mounted, and at other times the frequency is reduced and loss is suppressed. can do.

Next, a third embodiment of the charging device according to the present invention will be described with reference to FIG. FIG. 7 is a circuit diagram on the charger side showing a third embodiment of the charging device according to the present invention. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, two types of capacitors C21 and C22 are provided instead of the capacitor C2 so that they can be switched. The capacitor C22 has a normal capacitance value equal to that of the capacitor C2, and the capacitance value of the capacitor C21 is C21> C22. Further, instead of the light emitting diode D2, the coil portion of the relay 5 is connected, and the contact portion of the relay 5 is provided between the positive electrode of the DC power supply 1 and the primary winding L1. That is, the relay 5
Is connected to the negative electrode of the DC power supply 1, the capacitor C21 is connected to the contact NC, and the capacitor C22 is connected to the contact NO.

Next, the operation of the third embodiment will be described. When it is detected that there is no load or a conductor is placed, the output terminal 33 outputs an “L” level signal, and the contact of the relay 5 is the contact N on the side of the capacitor C21.
Stay connected to C.

On the other hand, when it is detected that the load device is attached, an "H" level signal is output from the output terminal 33, the relay 5 is activated, and the connection is made from the contact NC to the capacitor C.
Switch to contact No. 22 side.

In this way, by switching the capacitors C21 and C22 to be connected depending on the state of the load, oscillation is performed at the normal frequency only when the load device is mounted, and at other times, the frequency is reduced and loss is suppressed. can do.

[0047]

As described above, the present invention is a charger having a primary winding of the oscillation transformer, in which a load device having a storage battery connected to the secondary winding of the oscillation transformer can be attached and detached. In the charging device capable of supplying the output from the charger to the load device by mounting, the detecting means for detecting the oscillation frequency in the primary winding of the oscillation transformer of the charger and the detected oscillation frequency are Since the output control means for lowering the output of the charger is provided when the frequency is equal to or higher than the preset frequency, it is possible to reduce the loss in the no-load state. Further, when the conductor is placed on the charger, it is possible to suppress the generation of eddy current and prevent its heat generation.

[Brief description of drawings]

FIG. 1 is a circuit diagram on a charger side showing a first embodiment of a charging device according to the present invention.

FIG. 2 is a diagram showing an oscillation waveform on the charger side, in which (a) shows no load without a load device, (b) shows a load device, and (c) shows a conductor. This is the case of an anomaly placed.

FIG. 3 is a characteristic diagram showing a relationship between a load state and an inductance.

FIG. 4 is a flowchart showing the operation of the charging device.

FIG. 5 is an example of an output waveform at the output end of the microcomputer.

FIG. 6 is a circuit diagram on the charger side showing a second embodiment of the charging device according to the present invention.

FIG. 7 is a circuit diagram on the charger side showing a third embodiment of the charging device according to the present invention.

FIG. 8 is an explanatory view schematically showing a conventional non-contact type charging device.

FIG. 9 is a circuit diagram showing the charging device.

FIG. 10 is an example of a circuit diagram of a conventional contact type charging device.

[Explanation of symbols]

 1 DC power supply 2 F-V conversion circuit 3 Microcomputer 4,5 Relay 31 Input end 32,33 Output end C1, C2, C21, C22 Capacitor D1 Diode D2 Light emitting diode FET1 Field effect transistor L1, L11, L12 Primary winding L3 Feedback winding L4 Auxiliary winding Q1, Q2 Transistor R1 Starting resistance R2, R3, R4, R5 Resistance

Claims (3)

[Claims] 1. A charger having a primary winding of the oscillation transformer, wherein a load device having a built-in storage battery connected to a secondary winding of the oscillation transformer can be attached and detached. In a charging device capable of supplying an output from a charging device to the load device, a detecting means for detecting an oscillation frequency in a primary winding of an oscillation transformer of the charger, and the detected oscillation frequency is equal to or higher than a preset frequency. In this case, an output control means for reducing the output of the charger is provided. 2. The output control means intermittently drives the oscillation of the charger when the detected oscillation frequency is equal to or higher than a preset frequency. Charging device. 3. The output control means is composed of frequency switching means for lowering the oscillation frequency of the charger when the detected oscillation frequency is equal to or higher than a preset frequency. Item 1. The charging device according to item 1.