JPH11187582A - Electromagnetic induction power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of an electromagnetic induction power supply so that it can be applied to a portable article or a small electric apparatus while reducing resonance noise and suppressing increase of the number of parts by preventing fluctuation of the resonance frequency due to fluctuation of input or load and supplying power stably to a secondary circuit thereby eliminating need of a power supply stabilizing circuit on the secondary. SOLUTION: An electromagnetic induction power supply comprises a primary circuit 10 where AC power from a commercial power supply P is converted through a rectifier circuit 11 into DC power being fed to a resonance circuit 12 and means 13 for delivering the signal from an independent oscillation circuit through a switching circuit is connected with the resonance circuit 12, and a secondary circuit 20 where a signal transmitted at a secondary resonance circuit 21 through electromagnetic induction is rectified through a secondary rectifier circuit 22 to produce DC power being supplied to a load 23. Fluctuation in the voltage and current of the load on the secondary circuit is delivered from a load information detecting section 24 to a secondary information input section 14 without touching and signals are transmitted intermittently from an oscillation signal output means 13 thus controlling secondary power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic induction power supply capable of supplying electric power to portable equipment, small electric equipment and the like without contact.

[0002]

2. Description of the Related Art When power is supplied to an electric toothbrush, a power tool, a mobile phone, or the like, a device body having a load such as a secondary battery or a driving motor is provided so as to be separable from the power supply body. A method of supplying power from the main body to the device main body via electromagnetic induction coupling is generally used.

As an example of using such a power supply device by electromagnetic induction coupling, for example, the invention of a charging device disclosed in Japanese Patent Application Laid-Open No. 6-46531 is known. This charging device
A coil induced voltage generated by resonating high frequency power with a power supply coil from a primary side circuit in which a high frequency power generation circuit for converting DC power to high frequency power and a resonance circuit including a power supply coil are connected in parallel is defined as a primary voltage. To the coil of the secondary circuit 2
In this method, a secondary voltage is induced to supply power, and a charged device including a secondary battery is charged.

In this charging device, a combination of a charging and discharging capacitor and a switching element is used as a high-frequency power generation circuit. When power is supplied to the resonance circuit by high-frequency power, resonance occurs and a power supply coil of several tens of kilohertz is applied to the power supply coil. High frequency oscillation is obtained.

[0005] Further, in the secondary circuit of the charging device,
The voltage information of the next battery is sent to the primary circuit by the transmission circuit, and the control circuit of the primary circuit induces or stops the coil induced voltage.

As another example of a device provided with a power supply device utilizing electromagnetic induction coupling, a device disclosed in Japanese Patent Application Laid-Open No. 6-31658 is known. The device disclosed in this publication supplies power by electromagnetic induction coupling to a device body detachably mounted on a power source body that supplies power, and when the device body is mounted on the power source body, the power is supplied from the power source body. A power supply main body sends a predetermined detection signal to the main body of the apparatus, and receives a response signal sent from the main body main body based on the signal. I have.

In this device, when power is supplied from the power supply main body to the equipment main body, the power is supplied by identifying the equipment main body so as not to generate heat due to eddy current by erroneously recognizing a metal piece or the like as a load. I have.

[0008]

As described above, a power supply device for supplying power using electromagnetic induction coupling is widely used in portable products, and as a result, a secondary power supply is provided in the product. When assembling, it is required to reduce the size as much as possible. Further, in a device having a current exceeding 500 mA, the heat generated by the secondary power supply cannot be ignored.

On the other hand, such a power supply generally sends a DC power converted from a commercial AC power to a primary resonance circuit, and transmits a signal resonated by the resonance circuit to a secondary resonance circuit as it is. When the primary side resonance circuit is configured, there are a self-excited oscillation type and a separately excited oscillation type, and the latter (Japanese Unexamined Patent Application Publication No.
1658) is a self-excited type, the former (Japanese Patent Laid-Open No. 6-46553).
No. 1) belongs to the separately excited oscillation type, but is not synchronized with the resonance circuit.

In particular, in the case of a self-excited oscillation type oscillation circuit, the resonance frequency changes due to fluctuations in the input voltage to the oscillation circuit and load conditions due to the configuration of the oscillation circuit. In the example of the first patent publication, the battery voltage information on the secondary side is transmitted to the primary side by a non-contact transmission means so as to suppress the change in the resonance frequency due to the load fluctuation on the secondary side. It is not possible to suppress a change in resonance frequency due to a change in voltage.

When the resonance frequency of the primary side changes, the signal is sent to the secondary side as it is. Therefore, the resonance frequency of the secondary side is also affected and changes, so that radiation noise and line noise increase, and the secondary side power supply Circuit stability cannot be obtained,
In addition, due to the misalignment, the power supply to the secondary side decreases, and the energy transmission efficiency decreases. Therefore, in order to stabilize the voltage and current of the secondary circuit, a special circuit for stabilization must be provided, which increases the number of parts of the secondary circuit, heat generation of parts, and high cost. In addition, the switching frequency cannot be increased to prevent noise,
The miniaturization of the equipment cannot be measured beyond a certain level, which is a major obstacle when introducing an electromagnetic induction power supply.

According to the present invention, a separately excited oscillation type is used for the primary-side resonance circuit to supply a stable power to the secondary-side circuit so that the resonance frequency does not change due to fluctuations in the input voltage or the load state. It is an object of the present invention to provide an electromagnetic induction power supply that is small in noise and does not increase the number of parts, thereby reducing the size of the secondary power supply and adapting to miniaturization of portable products.

[0013]

According to the present invention, as a means for solving the above problems, a primary resonance circuit having a resonance coil and a capacitor for generating a primary voltage in a predetermined resonance state when DC power is transmitted is provided. Oscillation signal output means connected so as to output the signal from the independent oscillation circuit to the resonance circuit via a switching circuit that operates in synchronization with the oscillation frequency. A primary power supply circuit adapted to synchronize with a frequency; and a secondary voltage resonating from the primary resonance circuit to a secondary resonance circuit by electromagnetic induction coupling to supply secondary power.
The electromagnetic induction power supply device is provided so as to be separable from the secondary power supply circuit.

According to the electromagnetic induction power supply of the present invention having the above-described configuration, the resonance frequency in the resonance circuit is converted into a primary signal as a stable signal without being affected by the input voltage of the primary circuit or the voltage fluctuation on the load side. Is transmitted from the side to the secondary side and supplies stable power to the secondary side circuit.

The oscillating signal output means oscillates a high-frequency signal by an independent oscillating circuit, outputs the signal via a switching circuit, and inputs the signal to a primary-side resonance circuit. By appropriately setting the time constants of L and C, a resonance signal is generated in synchronization with the oscillation frequency of the oscillation circuit.

When a high-frequency oscillation signal is input by the switching circuit, the time during which the switching circuit is turned on and off is tuned to the frequency of the oscillation circuit. If the time constants of L and C are determined so as to advance by an angle, the largest waveform portion of the oscillation waveform of the resonance circuit generated in synchronization with the frequency of the oscillation circuit can be obtained in synchronization with the frequency of the oscillation circuit.

Therefore, the signal is transmitted to the secondary side in a state where the waveform is the largest. The vibration waveform also generates a small waveform vibration following the maximum waveform, but when the small waveform is generated, the next high-frequency signal is input from the outside, and as a result, the small waveform is cut and the secondary waveform is generated by the maximum waveform vibration. Is transmitted.

The above-mentioned independent oscillation circuit is not a circuit in which a resonance signal generated by a resonance circuit such as a self-excited resonance circuit is set by a signal from a circuit looping with the resonance circuit.
This is for configuring a separately-excited resonance circuit that externally inputs a high-frequency signal generated independently of the resonance circuit to the resonance circuit.

In this way, when the secondary power supply circuit is joined to the primary resonance circuit that resonates in synchronization with the high frequency oscillation signal of the oscillation circuit, the secondary resonance circuit is connected to the secondary resonance circuit by electromagnetic induction coupling.
A secondary side voltage is induced, and by rectifying this, secondary side power is supplied to the load.

When the voltage and current of the load of the secondary circuit fluctuate, the information is transmitted to the primary power supply circuit in a non-contact manner, and is transmitted to the primary resonance circuit of the signal from the oscillation circuit via the switching circuit. It is good to control the passage of. in this case,
The switching circuit is provided with a second switching circuit separately from the one tuned to the frequency of the oscillating circuit, and controls passage and blocking of a signal from the oscillating circuit by secondary side information.

The second switching circuit allows the signal of the oscillating circuit to pass when the voltage and current of the load fall below the set level, and prevents the signal from passing when the load voltage and current fall above the set level. For this reason, the oscillation signal becomes intermittent, the signal from the primary side circuit also becomes intermittent, and the secondary power decreases. If the intermittent time is reduced, the signal passes and the secondary power increases. .

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram of the electromagnetic induction power supply device of the embodiment. 10 is a primary side power supply circuit,
Reference numeral 20 denotes a secondary-side power supply circuit. In addition, this power supply
It is used as a power supply device of a secondary battery application product such as a portable device such as a mobile phone, or a small electric device such as an electric toothbrush or a shaving device.

As shown in FIG. 1, the primary power supply circuit 10
A rectifier circuit 11 for rectifying AC power obtained from an external commercial power supply P to obtain DC power; a resonance coil 12L and a capacitor 12C for generating a primary voltage in a predetermined resonance state from the current when the DC power is sent; Resonance circuit 12 comprising
(Primary side), a signal oscillated at a predetermined frequency is output to the resonance circuit, and the resonance circuit 12 is turned on and off by the signal.
Oscillation signal output means 13 for causing damped oscillation in the above, the load current in the secondary side circuit to this output means,
A secondary information input unit 14 for inputting voltage information.

The secondary side circuit 20 includes a secondary side resonance circuit 21 including a resonance coil 21L and a capacitor 21C, a rectification circuit 22 for rectifying a secondary voltage induced by electromagnetic induction coupling in a non-contact manner in the resonance circuit, A load 23 such as a secondary battery or a motor for storing rectified and converted DC power, load information such as the stored current and voltage, and load information detection for sending information to the primary side in a non-contact manner. A part 24 is provided.

The primary and secondary power supply circuits 10 and 20
2 and 3 are shown in FIGS. 2 and 3, respectively. Hereinafter, the details not shown in FIG. 1 will be described. As shown in FIG. 2, the oscillation signal output means 13 includes an independent oscillation circuit 13G. The oscillation frequency of the oscillation circuit 13G is a high frequency of, for example, about 250 KHz, and the DC power rectified by the rectification circuit 11 is used as a power supply. The control power supply unit 13P is connected to a power supply line, so that stabilized power is supplied so that the oscillation frequency does not change.

The oscillating signal of the oscillating circuit 13G is equal to two signals of the first switching circuit 13S and the second switching circuit 13SS.
The signal is output to the resonance circuit 12 via one switching circuit. The first switching circuit 13S has an LC
The switching is performed in accordance with the oscillation frequency of the oscillation circuit 13G which is the fundamental frequency of the resonance circuit 12 on the primary side, which is a resonance circuit. A signal synchronized with the signal is sent to the resonance circuit 12.

The second switching circuit 13SS is composed of a switching element such as a NOR gate element in principle, and passes and blocks the signal of the oscillation circuit 13G by the voltage and current information signals from the secondary side information input unit 14. It controls switching. In the illustrated example, the voltage and current information of the secondary circuit is a light receiving element 14 that receives an infrared light signal.
The output signal a is shaped into a rectangular wave by the waveform shaper 14b and sent to the circuit 13SS.

The second switching circuit 13SS
If the signal of the secondary information input unit 14 is an H signal, the oscillation circuit 1
The 3G signal is blocked, and if the signal is an L signal, the oscillation signal is passed. The switching operation is set to a frequency sufficiently lower than the frequency of the oscillation circuit 13G, so that the switching operation is performed irrespective of the frequency of the oscillation circuit 13G and is provided so as not to affect the oscillation frequency of the oscillation circuit 13G.

As for the secondary side circuit 20, a part shown in detail in FIG. 3 will be described. That is, the load information detection unit 24
Has a voltage and current detector 24a, compares the voltage or current value of the load 23 with a voltage setting level set as a reference voltage in an operational amplifier,
If the signal is low, an H signal is output. The above signal is sent to the light emitting driver 24b, and the driving signal controls on / off of the infrared light emitting element 24c.

The light signal of the light emitting element 24c is generated when the secondary circuit 20 is joined to the primary circuit 10.
It is assumed that the light receiving element 14a receives light and the secondary side voltage and current information is transmitted. In the illustrated example, the information transmission means is of the optical signal type, but may be an ultrasonic signal or a radio signal instead of the optical signal.

The operation of the electromagnetic induction power supply of this embodiment having the above-described configuration is as follows. DC power is supplied to the LC resonance circuit 12 of the primary circuit 10, and a high-frequency oscillation signal is input from the oscillation circuit 13G to the resonance circuit 12 based on the DC power. A primary voltage is generated by the resonance signal.

The resonance waveform in the resonance circuit 12 is obtained by converting the oscillation signal of the oscillation circuit 13G into the first switching circuit 13S.
Based on the signal passed through. That is, assuming that the oscillation waveform of the oscillation circuit 13G is a waveform as shown in FIG. 4A, the current is amplified by the first switching circuit 13S, and the output signal of the oscillation circuit 13G serves as a switch for flowing or stopping the current to the resonance circuit 12. Works.

When the first switching circuit 13S is turned on and the LC
When a current flows through the resonance circuit 12 and turns off, the resonance circuit 12
Causes damped oscillation to produce a damped oscillation waveform as shown in FIG. 4 (b). Therefore, the time when the first switching circuit 13S is turned on and off is the frequency of the oscillation circuit 13G,
If the time constants of L and C of the LC resonance circuit 12 are determined so that the damped oscillation advances by 180 ° during the off time of the first switching circuit 13S, the maximum oscillation waveform is synchronized with the oscillation of the oscillation circuit 13G. Since the oscillation waveform can be generated in accordance with the oscillation waveform and the oscillation waveform of a small waveform is cut, a signal can be transmitted to the secondary side in a state where the waveform is the largest.

The signal of the damped oscillation waveform generated in the LC resonance circuit 12 is received as the oscillation waveform tuned to the primary resonance frequency by the secondary resonance circuit 21 based on the principle of electromagnetic induction coupling, and the primary and secondary signals are received. The next resonance circuits 12 and 21 resonate at the same frequency and transmit power in a non-contact manner. The signal received by the secondary side resonance circuit 21 is rectified by the secondary side rectification circuit 22 and used as secondary side power.

The power on the secondary side is supplied to a load 23 such as a secondary battery or a motor, and the power required for the load changes as the state of charge of the secondary battery approaches a fully charged state. As described above, such information on the secondary side voltage and current is detected by the voltage / current detection circuit 24a and transmitted from the light emitting element 24b to the primary side light receiving element 14a.

The optical signal is sent to the second switching circuit 13SS as an L signal when the voltage on the secondary side is higher than the voltage setting level, and as an H signal when the voltage is lower than the voltage setting level. The passage of the signal of the oscillation circuit 13G is stopped, and if the signal is an L signal, the signal is controlled to pass. The first and second switching circuits 13S, 13S
FIG. 5 shows an overall process of creating a resonance waveform generated in the resonance circuit 12 on the primary side via S.

Since the oscillation waveform of the oscillation circuit 13G is continuously generated at a constant high frequency as shown in FIG.
The resonance signal in the resonance circuit 12 on the primary side also transmits a signal to the secondary side as a signal tuned to the resonance signal to send power.
The voltage state on the load side changes, and as shown in FIG.
When a fluctuation that is higher or lower than the voltage setting level occurs, a signal having a pulse width corresponding to the magnitude of the voltage fluctuation is generated as shown in FIG.
A signal shown in (e) is output from the voltage / current detector 24a, and a signal having an operation waveform as shown in FIG. 5 (c) is input to the second switching circuit 13SS.

Therefore, the oscillation waveform that has passed through the first switching circuit 13S is such that the oscillation waveform is removed only during the period when the L signal is input to the second switching circuit 13SS, as shown in FIG. As a result, the oscillation waveform becomes intermittent, and the resulting damped oscillation waveform in the resonance circuit 12 also becomes intermittent as shown in FIG. 5B.

As described above, if the degree of the intermittent intermittent oscillation waveform is controlled based on the secondary voltage and current information, the intermittent period is reduced as the secondary voltage and current decrease, and the voltage approaches the voltage setting level. By increasing the intermittent period, the power from the primary side circuit 10 to the secondary side circuit 20 can be changed, so that the desired secondary side voltage,
A current state can be obtained.

As described above, the rate at which power is supplied from the primary circuit to the secondary circuit is increased or decreased due to load fluctuation.
Even if the load on the secondary circuit fluctuates because the resonance circuit of the secondary circuit is separately excited, the resonance frequency of the resonance circuit itself is affected and fluctuated by the fluctuation of the load as in the self-excitation type. There is no.

Also, even if the DC power supply of the primary circuit changes due to the fluctuation of the commercial power supply, the oscillation frequency of the oscillation circuit 13G hardly changes, and stability is secured by connecting the control power supply 13P to the oscillation circuit 13G. doing. Therefore, the resonance frequency does not change unlike the self-excited electromagnetic induction device, regardless of the fluctuation of the input voltage on the primary side or the load on the secondary side, and stable power is supplied to the secondary side circuit. Can be.

[0042]

As described in detail above, the electromagnetic induction power supply of the present invention provides a high frequency signal from the oscillation signal output means having an independent oscillation circuit and a switching circuit to the primary resonance circuit having a resonance coil and a capacitor. Input to generate a resonance signal in the resonance circuit in synchronization with the high-frequency signal, and the signal is transmitted to the secondary-side resonance circuit by electromagnetic induction coupling to supply power to the secondary-side circuit. Since the signal is transmitted to the secondary side with the resonance signal having the maximum waveform among the attenuation signals in the resonance circuit on the primary side, the degree of coupling of electromagnetic induction is increased, and the resonance signal is affected by variations in input voltage and load. The power supply circuit can be supplied with high efficiency and stable power to the secondary side circuit, and there is no need to provide a power stabilizing power supply in the secondary side circuit. Therefore, the power supply circuit can be downsized and the number of components can be suppressed. What Various effects can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall schematic block diagram of an electromagnetic induction power supply device.

FIG. 2 is a block diagram of a primary circuit according to the first embodiment;

FIG. 3 is a block diagram of a secondary circuit of the above.

FIG. 4 is an explanatory diagram of waveforms of an oscillation circuit and a resonance circuit.

FIG. 5 is an explanatory diagram of oscillation and waveform change of a resonance circuit due to load fluctuation information.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Primary circuit 11 Rectifier circuit 12 Resonant circuit 13 Oscillation signal output means 14 Secondary information input part 13G oscillator circuit 13S 1st switching circuit 13SS 2nd switching circuit 20 Secondary circuit 21 Resonant circuit 22 Rectifier circuit 23 Load 24 Load information detector

Claims (2)

[Claims] An apparatus having a resonance coil and a capacitor for generating a primary voltage in a predetermined resonance state when DC power is transmitted.
A secondary resonance circuit, and oscillation signal output means connected to output the signal from the independent oscillation circuit to the resonance circuit via a switching circuit that operates in synchronization with the oscillation frequency, and the predetermined resonance state is provided. And a secondary power supply that induces a secondary voltage that resonates from the primary resonance circuit to the secondary resonance circuit by electromagnetic induction coupling from the primary power supply circuit that synchronizes the power with the oscillation frequency of the oscillation circuit. An electromagnetic induction power supply device which is provided with a secondary power supply circuit capable of being separated. A second power supply circuit which operates by a load information signal between an oscillation circuit and a switching circuit in the primary side power supply circuit.
The secondary power supply circuit is provided with a load state detecting means for detecting a change in the voltage or current of the load, and the information detected by the detecting means is transmitted in a non-contact manner,
2. The electromagnetic induction power supply according to claim 1, wherein when the information signal is received by the receiving means, the second switching circuit is operated by the output signal.