JPH11168839A - Non-contact-type charging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a standby state at the side of a charging part and to automatically stop operation of the charging part, by providing a temperature detection circuit for detecting the temperature of a switching circuit at the charging part, and controlling power being supplied to a primary coil based on the output of the temperature detection circuit. SOLUTION: A voltage and a current being generated at a switching circuit 18 due to a rectangular waveform voltage from a driver circuit 17 become waveforms. Then, when the voltage and the current waveforms overlap, a switching circuit 18 generates heat. A reference voltage Vref is set to a voltage value that is equal to a voltage being applied to a contact A when the temperature of the switching circuit 18 becomes 60 degrees. Then, when the temperature of the switching circuit 18 is 60 degrees or less, a high-level signal is outputted from the output terminal of a comparator. On the other hand, when the temperature exceeds 60 degrees, a low-level signal is outputted. The operation of the driver circuit 17 is stopped when the output signal of the comparator changes from a high to low level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a charging section connected to a power supply, which is provided in a charging section separately from the charging section by contactlessly supplying power to the charging section. The present invention relates to a non-contact charging device that charges a battery.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a circuit configuration of a conventional non-contact charging device. As shown in FIG. 1, in the charging unit 10, the AC power from the commercial power supply 3 is supplied to the full-wave rectifier circuit 11a.
DC power supply circuit 11 comprising a capacitor and a smoothing capacitor 11b
Is converted to DC power. This DC power is on / off controlled by a switching circuit 18 driven by a rectangular wave voltage from a driver circuit 17, and is intermittently supplied to the primary coil 12.

[0003] In the charged part 2, the primary coil 12
The two coils 12, 2
An induced current due to the electromagnetic induction action between the two flows, and the induced current is supplied to the battery 24 after being smoothed by the smoothing capacitor 23. Thereby, the battery 24 is charged.

A non-contact charging device is different from a contact charging device in that a primary coil 12 and a secondary coil 21 are different from each other.
Because the magnetic gap between them is large, the leakage flux increases,
The surge voltage increases. This surge voltage is
The voltage is generated between the collector and the emitter of the switching circuit 18 when the rectangular wave voltage output from the driver circuit 17 falls, and depending on the magnitude thereof, the switching circuit 1
8 may be destroyed.

For this reason, usually, a capacitor 14 is connected in parallel to a switching circuit 18 and the capacitor 14
By forming a resonance circuit with the leakage inductance between the first coil 12 and the second coil 21, the surge voltage is suppressed. By making the resonance frequency of this resonance circuit equal to the switching frequency of the switching circuit 18 (the frequency of the rectangular wave voltage of the driver circuit 17), an ideal resonance circuit having no switching loss can be obtained.

As a result, the voltage and current generated in the switching circuit 18 have waveforms shown by solid lines in FIGS. 3B and 3C, and the waveforms are switched without overlapping in terms of timing.

When there is an overlapping portion between the voltage waveform and the current waveform, the power of the overlapping portion becomes a switching loss and causes the switching circuit 18 to generate heat.

[0008]

Generally, the charging unit 10 of this type of non-contact type charging apparatus is always operated at all times, and for example, a switch for stopping the operation of the charging unit 10 is provided. Even if the switch is forgotten to be turned off, the charging unit
At 0, the switching operation of the switching circuit 18 is performed.

Therefore, in a standby state in which the charged portion 2 is not located at a predetermined position, most of the magnetic flux generated from the primary coil 12 of the charging portion 10 becomes leakage magnetic flux.
The leakage inductance increases, and the resonance frequency of the resonance circuit including the leakage inductance and the capacitor 14 decreases.

For this reason, the voltage applied to the switching circuit 18 changes from the waveform shown by the solid line to the waveform shown by the dashed line in FIG. 3 (b), and the portion shown by the diagonal lines in FIG. This switching loss becomes heat,
The temperature of the switching circuit 18 rises, and the temperature rise may cause the switching circuit 18 to be degraded or destroyed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and detects a standby state in which a portion to be charged is not located at a predetermined position. It is an object of the present invention to provide a non-contact charging device in which the operation of the battery is automatically stopped.

[0012]

According to the present invention, there is provided a contactless charging apparatus in which a charging section and a charged section are separated from each other, and the charging section is supplied to a primary coil and the primary coil. A switching circuit for controlling on / off of the DC power, and a driver circuit for driving the switching circuit with a rectangular wave voltage at a predetermined interval, wherein the charged part is electromagnetically coupled to the primary coil; In a non-contact charging device comprising a battery connected to the coil,
A temperature detection circuit for detecting the temperature of the switching circuit, and a control circuit for controlling the power supplied to the primary coil based on the output of the temperature detection circuit are provided. In such a configuration, when the charging unit is in the standby state and the electromagnetic coupling between the primary coil of the charging unit and the secondary coil of the charged unit is released, the leakage inductance is compared with the charging state. Becomes larger, so that the resonance frequency decreases.
Therefore, the switching circuit is turned on before the voltage applied to the switching circuit becomes zero, and current starts to flow while the voltage is applied. A period during which the voltage and the current are simultaneously generated becomes a switching loss, and the energy thereof becomes heat, thereby increasing the temperature of the switching circuit. The temperature of the switching circuit is detected by a temperature detection circuit, and the power supplied to the primary coil is controlled based on the detected value.

When the temperature detected by the temperature detection circuit is equal to or lower than a predetermined temperature, power is supplied to the primary coil, and the temperature detected by the temperature detection circuit decreases the predetermined temperature. When it exceeds, the power supplied to the primary coil is controlled to be cut off.

In the control circuit, after the power supplied to the primary coil is once cut off, the temperature detected by the temperature detection circuit becomes equal to or lower than the second temperature lower than the first temperature. At this time, control is performed so that power supply to the primary coil is restarted.

Further, the control circuit controls the power supply to the primary coil to be prohibited for a certain period of time after the power supplied to the primary coil is interrupted.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram illustrating a circuit configuration of a non-contact charging device according to an embodiment of the present invention. It is to be noted that the same configurations as those in the related art are denoted by the same reference numerals.

As shown in FIG. 1, the charging unit 1 includes a DC power supply circuit 11 connected to the commercial power supply 3, a primary coil 12 connected to the DC power supply circuit 11,
Circuit 18 for controlling on / off of the electric power supplied to primary coil 12 from
And a driver circuit 17 for driving the same. Further, the charging unit 1 includes the capacitor 14 as a snubber circuit connected in parallel to the switching circuit 18. Further, the charging unit 1 includes a thermistor 15 as a temperature detection circuit arranged near the switching circuit 18 and a control circuit 16 connected to the thermistor 15.

The DC power supply circuit 11 includes a full-wave rectifier circuit 11a.
The AC power input from the commercial power supply 3 is rectified by the full-wave rectifier circuit 11a, and then smoothed by the smoothing capacitor 11b to output DC power.

The driver circuit 17 outputs a rectangular wave voltage shown in FIG. 3A, and controls the switching circuit 18 on / off by the rectangular wave voltage. When the capacitor 14 connected in parallel to the switching circuit 18 is in a charged state, the resonance frequency of the resonance circuit including the capacitor 14 and the leakage inductance between the primary coil 12 and the secondary coil 21 changes the switching frequency of the switching circuit 18. The capacitance is set to match the frequency (frequency of the rectangular wave voltage of the driver circuit 17). Further, in the present embodiment, the frequency of the rectangular wave voltage is set to 100 kHz.

As a result, the voltage and current generated in the switching circuit 18 by the rectangular wave voltage from the driver circuit 17 have the waveforms shown by the solid lines in FIGS. 3B and 3C, and the two waveforms overlap in timing. Switching is performed without any change. If there is an overlapping portion between the voltage waveform and the current waveform, the power in the overlapping portion becomes a switching loss and causes the switching circuit 18 to generate heat.

The thermistor 15 includes a switching circuit 18
Is attached with an adhesive. This thermistor 15
It has a substantially linear temperature characteristic. For example, when the temperature of the switching circuit 18 is 1 kΩ when the temperature is 30 degrees, the resistance value decreases as the temperature of the switching circuit 18 rises, and becomes 500 Ω when the temperature is 60 degrees. is there.

As shown in FIG. 2, the control circuit 16 includes a voltage dividing resistor 16a and a comparator 16b. The voltage dividing resistor 16a is connected in series to the thermistor 15 between the constant voltage source Vcc and the ground GND. The voltage at the contact A between the thermistor 15 and the voltage dividing resistor 16a is input to one input terminal of the comparator 16b,
The reference voltage Vref is input to the other input terminal.

The reference voltage Vref is supplied to the switching circuit 18
Is set to a voltage value equal to the voltage applied to the contact A when the temperature reaches 60 degrees. Therefore, a high-level signal is output from the output terminal of the comparator 16b when the temperature of the switching circuit 18 is equal to or lower than 60 degrees, and a low-level signal is output when the temperature of the switching circuit 18 exceeds 60 degrees. A signal is output.

The driver circuit 17 includes a comparator 16b
While the output signal is at a high level, a rectangular wave voltage is output. When the output signal changes from a high level to a low level, the operation is stopped based on the change of the output signal.

On the other hand, the portion to be charged 2 is arranged close to the primary coil 12 of the charging unit 1 so that the primary coil 12
Coil 21 electromagnetically coupled with the secondary coil 21
And a smoothing capacitor 23 connected to the diode 22.

When an induced current is generated in the secondary coil 21 by the electromagnetic induction between the primary coil 12 and the secondary coil 21, the current is rectified by the rectifying diode 22 and then rectified by the smoothing capacitor 23. And supplied to the battery 24. Thereby, the battery 24 is charged.

In the charging device having such a configuration, as described above, when the operation of the charging unit 1 is performed in the charging state in which the charged unit 2 is arranged at a predetermined position, the switching frequency of the switching circuit 18 is changed as described above. Are set so as to substantially coincide with the resonance frequency of the resonance circuit including the capacitor 14 and the leakage inductance between the first coil 12 and the second coil 21, so that switching loss does not occur. Therefore, the temperature of the switching circuit 18 rises only slightly, and does not become high.

However, when the operation of the charging unit 1 is performed in a standby state where the charged unit 2 is not located at a predetermined position, the secondary coil 21 does not exist, so that the primary coil 12 generates. Most of the magnetic flux becomes a leakage magnetic flux, and the leakage inductance due to the leakage magnetic flux becomes larger than that in the charged state. For this reason, the resonance frequency of the resonance circuit becomes low, and the voltage applied between the collector and the emitter of the switching circuit 18 changes from the waveform shown by the solid line in FIG.

As a result, a portion overlapping the current waveform flowing between the collector and the emitter of the switching circuit 18 shown in FIG. 3C occurs, and the power corresponding to this overlapping portion becomes a switching loss, and the switching circuit 18 generates heat. Let it. Therefore, the temperature of the switching circuit 18 rises with time and reaches 60 degrees.

When the temperature of the switching circuit 18 reaches 60 degrees, the output signal of the comparator 16b changes from a high level to a low level, and in response to this signal change, the operation of the driver circuit 17 is automatically stopped. Driver circuit 1
When the operation of 7 is stopped, the switching circuit 18 is cooled by the outside air, and the temperature decreases.

The driver circuit 17 whose operation has been stopped is restarted by operating a reset button (not shown). According to the present embodiment, by detecting the temperature of switching circuit 18, it is possible to detect a standby state in which charged part 2 is not disposed at a predetermined position. The power supply to the next coil 12 is cut off, so that excessive heat generation of the switching circuit 18 can be avoided. Thus, the switching circuit 18 is not deteriorated or destroyed by heat, and power consumption in the standby state can be reduced.

In the above embodiment, a manual method is used as a method of restarting the operation of the driver circuit 17 whose operation has been stopped, but the present invention is not limited to this.

For example, the operation of the thermistor 15 and the control circuit 16 is continued even after the operation of the driver circuit 17 is temporarily stopped due to the temperature rise of the switching circuit 18,
When the temperature of the switching circuit 18 decreases to a predetermined temperature, the operation of the driver circuit 17 may be automatically restarted. The temperature at which the operation of the driver circuit 17 is restarted is set to a temperature sufficiently lower than the temperature at which the operation of the driver circuit 17 is stopped. For example, the driver circuit 1
If the temperature at which 7 is stopped is 60 degrees, the temperature at which it is restarted is set to about 40 degrees. This protects the switching circuit 18 against temperature rise,
The operation for restarting the operation of the charging unit 1 can be omitted.

Further, the operation of the charging unit 1 may not be restarted for a certain period after the operation of the driver circuit 17 is temporarily stopped due to the temperature rise of the switching circuit 18. As a result, the cooling time of the high-temperature switching circuit 18 is ensured, the switching circuit 18 is not used at a high temperature, and the switching circuit 18 can be protected against a rise in temperature.

In the above embodiment, the driver circuit 17 is stopped so that the power supply circuit
Although the case where the power supplied to the next coil 12 is cut off has been described, the present invention is not limited to this. For example, as shown in FIG. 4, a switching circuit 19 is interposed between the power supply circuit 11 and the primary coil 12 and the switching circuit 19 is released, so that the DC power supply circuit 11
2 may be shut off.

In the above embodiment, the thermistor 15 is used as the temperature detecting circuit. However, the present invention is not limited to this. For example, a thermostat may be used.

[0037]

According to the present invention, the standby state in which the portion to be charged is not disposed can be detected by detecting the temperature of the switching circuit. Power supply of the switching circuit can be cut off to avoid excessive heat generation of the switching circuit. Thus, the switching circuit is not deteriorated or destroyed by heat, and the power consumption in the standby state can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a circuit configuration of a non-contact charging device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a circuit configuration of a control circuit of the contactless charging device illustrated in FIG.

3 is a waveform diagram showing a waveform of a rectangular wave voltage (a) output from a driver circuit of the contactless charging device shown in FIG. 1, a voltage (b) and a current (c) generated in a switching circuit.

FIG. 4 is a block diagram illustrating a circuit configuration of a non-contact charging device according to another embodiment of the present invention.

FIG. 5 is a block diagram illustrating a circuit configuration of a conventional non-contact charging device.

[Explanation of symbols]

 1: Charger 11: Power supply circuit 12: Primary coil 14: Capacitor 15: Thermistor 16: Control circuit 17: Driver circuit 18: Switching circuit 2: Charged part 24: Battery

Claims (4)

[Claims] 1. A charging section and a charging section are separated from each other, and
The charging unit includes a primary coil, a switching circuit for controlling on / off of DC power supplied to the primary coil, and a driver circuit for driving the switching circuit with a rectangular wave voltage at a predetermined interval. In a non-contact charging device, a charging unit includes a secondary coil electromagnetically coupled to the primary coil, and a battery connected to the secondary coil, wherein the charging unit detects a temperature of the switching circuit. A non-contact charging device, comprising: a temperature detection circuit for controlling the power supplied to the primary coil based on an output of the temperature detection circuit. 2. The control circuit, when the temperature detected by the temperature detection circuit is equal to or lower than a first temperature, power is supplied to the primary coil, and the temperature detected by the temperature detection circuit is controlled by the control circuit. 2. The non-contact charging device according to claim 1, wherein when the temperature exceeds a first temperature, the power supplied to the primary coil is controlled to be cut off. 3. The control circuit according to claim 1, wherein after the power supplied to the primary coil is once cut off, a temperature detected by the temperature detection circuit is lower than a second temperature lower than the first temperature. 3. The non-contact charging device according to claim 2, wherein control is performed such that power supply to the primary coil is restarted when the following conditions are satisfied. 4. The control circuit according to claim 1, wherein once the power supplied to the primary coil is cut off, the control circuit controls the power supply to the primary coil to be prohibited for a certain period of time. Item 3. A non-contact charging device according to Item 2.