JPS62203526A - Radio power transmitter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wireless power transmission device that enables wireless power transmission between two electric circuits.

[Prior Art] Conventionally, power is transmitted to moving parts using wires. For this reason, troubles such as wire breakage due to repeated operation of moving parts frequently occur. Furthermore, although a technique for electrical connection using a brush has been proposed, the contact resistance of the brush changes over time, and maintenance such as constantly cleaning the contact surface requires a great deal of effort.

Therefore, in recent years, technology for transmitting power without contact has been developed, and a device has been proposed that uses a pair of magnetically coupled non-contact coils and uses magnetic force as a power transmission medium ( (Japanese Unexamined Patent Publication No. 58-115945).

[Problems to be Solved by the Invention] Conventional power transmission devices are installed in a portion where the air gap between the power transmitting coil and the power receiving coil does not change.

This device is used as an industrial turntable IT as shown in Fig. 10.
When used for this purpose, the following problems occur. The industrial turntable IT is composed of a table bottom having a first sensor detail S1 and a second sensor group S2, and a drive section B that rotates this table T by 180 degrees.
A first power receiving coil CP1 is connected to the sensor group S1,
A second power receiving coil CP2 is connected to the second sensor group S2. Then, depending on the position of the table T, the first power receiving coil CP1 or the second power receiving coil CP
A power transmission coil DC is installed to supply power to one of the two. Therefore, in the turntable IT, the table T rotates 180 degrees to alternately turn the first power receiving coil C
P1 or the second power receiving coil CP2 forms a steady power transmission gap with the power transmitting coil DC. Therefore, the gap between the two coils changes every time the table T is rotated. By varying the gap, the impedance of the power transmission coil DC becomes smaller when the gap becomes wider, as will be described later. As a result, when the impedance of the power transmission coil DC becomes small, the current flowing through the coil DC increases.

When this current is increased/JD, a problem arises in that the capacity of the switching means etc. that intermittent this current and the amount of heat dissipated increase.

[Means for Solving the Problems] As a means for solving the above-mentioned problems, the present invention provides: a switching means connected to one end of a power transmission coil, which switches on and off the current flowing through the power transmission coil at a power transmission frequency; In a wireless power transmission device equipped with a power transmitting coil and a receiving coil that transmits and receives power through a variable air gap, the air gap between the power transmitting coil and the power receiving coil is roughly defined as a steady power transmission gap that performs power transmission and reception when the gap between the power transmitting coil and the power receiving coil is steady. In this case, a configuration is adopted in which a wireless power transmission device is characterized in that a resonant capacitor having a capacitance that resonates in parallel at the power transmission frequency is connected in parallel to the switching means between the power transmission coil and the power transmission coil.

For example, a semiconductor switching element is used as the switching means.

The electrostatic capacitance resonance capacitor that resonates in parallel with the power transmission frequency is, for example, a capacitor that is provided to resonate in parallel with the transmitting coil at the oscillation frequency of the power transmitted from the transmitting coil to the receiving coil.

[Function] The present invention was made by focusing on the fact that the impedance of the coupler used for power transmission shown in FIG. 2 changes as the air gap changes. First, using FIG. 2, we show the state of impedance that changes with changes in the air gap, which is the point of interest. In Figure 2, A is a power transmission coil wound N1 times around an iron core "a" with core length Ω1, cross-sectional area S1, and magnetic permeability μm, and B
is N for core Fb with core length Ω2, cross-sectional area S2, and magnetic permeability μ2.
The receiving coil C, which is wound twice, is powered by a voltage V power source. The dotted line in FIG. 2 indicates the state of the magnetic flux Φ.

In Figure 2 above, the magnetic flux is Φ=N111/((Ω1/μm51) −F (Q 2 / μ232> + 2(d/
It is expressed by the formula μ0 33 )). <11
is the current flowing through the power transmission coil A, μO is the magnetic permeability of the air gap, and S
3 is the cross-sectional area of the air gap) In Fig. 2, when the spacing between the couplers becomes wider, that is, when d becomes larger, the magnetic flux resistance in the denominator in the above formula for calculating the magnetic flux Φ increases, so the magnetic flux increases. significantly reduced. Therefore, since the inductance L is expressed by the formula L=dΦ/di, when the distance between the couplers becomes wider, Φ decreases, and therefore the inductance decreases. Therefore, when an AC power source is applied to the power transmitting coil A, impedance is proportional to inductance, so when the distance between the couplers increases, the impedance of the power transmitting coil A decreases. As a result, the current flowing through the power transmission coil increases.

Next, the effect when the present invention is applied to the circuit shown in FIG. 3 will be described. In Figure 3, the power transmission coupler a1 that connects the power transmission coil
A wireless power transmission device is shown that includes a power receiving coupler b including a power receiving coil and a blocking oscillation circuit C. In the blocking oscillation circuit C, the collectors CC of transistors 1 to ct are connected to one end of the power transmitting coil aC, which is wound N1 times, and the input resistor R2 is wound N1 times between the base cb and emitter ce of the transistors ct. An oscillation coil aO1 and an oscillation capacitor C1 are inserted, and an oscillation resistor R1 for adjusting the oscillation frequency together with the oscillation capacitor C1 is connected to the (I) of the power transmission coil aC.
! ! It is inserted between the end aθ and one end ac1 of the oscillation capacitor C1.

FIG. 4 shows a circuit excluding the power receiving coupler b shown in FIG. 3 above. Conventionally, the power transmitting coupler a and the power receiving coupler b were connected as shown in Figure 3.
The distance (gap) between the two was approximately 3 mrn or less. At this distance, power was transmitted and received between the couplers.

In the present invention, when the gap between the two couplers is set apart by a predetermined gap, for example Q, 5 mm or more, the power transmission current I flowing through the transistor ct is prevented from increasing as shown in FIG. In Figure 5, the vertical axis shows the transmission current 1
(A>, the horizontal axis shows the inter-coupler gap d (mm). In FIG. 5, the transmission current increases as the inter-coupler gap increases.

Next, in order to prevent the increase in power transmission current shown in Figure 5,
In the present invention, as shown in FIG. 6, a resonant capacitor C2 is inserted between the collector and emitter of the transistor ct. In the circuit shown in FIG. 6 in which this resonant capacitor C2 is inserted, when the gear ψ between the couplers is 1.0 (mm>), at the blocking oscillation frequency of the oscillation circuit C, the resonant capacitor C
Parallel resonance occurs between the power transmitting coil aC and the power transmitting coil aC. In addition, the general resonance condition is expressed as f = 1/27rl when the frequency is f, the inductance of the coil is , and the capacitance of the capacitor is C. The above transmission current I characteristic is shown in Figure 7. In Fig. 7 shown in Figure 7, the transmission current I is the gap between the couplers d=1 (m
The characteristic is shown that Q(mrn) peaks at n>, increases from Q(mrn) to 1(mm), then decreases from 1(mm) to 2(mm>, and then remains constant. Therefore, the resonant capacitor C2 is By inserting it, it is possible to reduce the current that increases when the inter-coupler gap d is large.

[Example] An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram of a wireless power transmission device of this embodiment, FIG. 8 is a sectional view of a coupler used in the embodiment, and FIG. 9 is a block diagram of an example in which this embodiment is applied to an industrial turntable.

The wireless power transmission device 1 of this embodiment includes a power transmitting coil A, a power receiving coil B, a power source C, a switching means D, a resonant capacitor E, a power receiving power supply means F, a sensor group G, a signal transmitting means H1, and a signal receiving means I. It consists of

Electric power supplied from the power supply C and intermittent by the switching means flows through the power transmission coil A.

The power receiving coil B receives the power sent from the power transmitting coil 8 through magnetic coupling with the power transmitting coil A through an air gap.

The power supply C is equipped with a power supply battery 40C, and when it supplies power to the power transmission coil A, it is also equipped with a regulator 41C that supplies 5 (V) of power to the signal reception means I. There is.

In the above switching means, from the power supply C to the power transmission coil A
The power sent through the terminal is switched on and off. The above-described switching is performed by a blocking oscillation circuit composed of a transistor 45D, an oscillation coil 46D, an oscillation capacitor 47D, an oscillation resistor 48D, and an input resistor 49D. In this blocking oscillation circuit, the oscillation frequency fO1
For example, oscillation is performed at a repetition frequency of 10 (KH2>).

The resonant capacitor E is inserted between the collector 45Dc and emitter 45De of the transistor 45D. Is this resonant capacitor + JE the connection between the above power transmitting coil A and power receiving coil B? When the whelk is 1.0 (mrn),
The capacitance is set so that resonance occurs with the power transmission coil A at the oscillation frequency rO of the blocking oscillation circuit.

The receiving power supply means F converts the power received by the receiving coil B into a DC power source. That is, in this means F,
After rectifying and smoothing the AC power from the power receiving coil B with a diode 50F and a smoothing capacitor 51F, a DC stabilized voltage is generated in a voltage stabilization circuit consisting of stabilization 1 to transistor 52F, resistor 53F, and Zener diode 54F. Roughly 5 cm of voltage is generated from this DC stabilized voltage by the regulator 55F.

The above-mentioned sensor G includes various sensors that operate by receiving electric power from the power receiving power supply means F, and the data detected by the various sensors υ of this sensor G is output to the output terminal 57G. has been done.

The signal transmitting means 1-1 performs an operation 11 of transmitting data detected by the sensor group G to the signal receiving means I via the power receiving coil B and the oscillating coil 46D.

First of all, in this C, the parallel-serial converter 60)-1
The data input from the parallel input terminal 60 HD is converted into a serial signal SS consisting of high level and low level and output to the serial output terminal SO. Based on this serial signal SS, the 1If2 transmission oscillation circuit H1-1 oscillates 4
An operation of intermittent MHZ is performed. This single transmission wave oscillation circuit H)-1 includes a transmitting coil 61['', an oscillating coil 62H, a transistor 63H1, a variable resistor 64H1
A blogging oscillation circuit is constituted by oscillation capacitors 65H, a5 and oscillation resistor 66H. In this one-shell wave transmitting optical circuit IH, when the serial terminal SO of the parallel-to-serial converter 60)-1 is at a low level, one transmission is stopped. The carrier series signal SSH interrupted by the series signal @SS is connected to the coupling capacitor 68H1 and
The signal is transmitted to the signal receiving means (2) via the power receiving coil B and the oscillating coil 4.6D.

The signal receiving means 1 demodulates the carrier serial signal S S l- (transmitted from the signal transmitting means 1) and converts it into a parallel signal. First, in the signal receiving means 1, the coupling condenser 70 ②, and the one-piece transmission series signal SSH sent via the coupling transformer 711 to the smoothing capacitor 721 and the demodulation diode 73I.
Convert to serial signal SS. Next, the serial signal SS is input to the serial input terminal 81 of the serial-parallel converter 75I.
is added to convert the serial signal SS into a parallel signal.

This converted parallel signal is output from the parallel signal output terminal 751p. This parallel signal output terminal 7
At 5Ip, the input state of the parallel signal input terminal 60Hp of the corresponding parallel-to-serial converter 60H is output. For example, when the first terminal 60Hpl of the parallel signal input terminal 60Hf is at a low level, the first terminal 75Ip1 of the parallel signal output terminal 751p becomes a high level.

As shown in Figure 1 above, power is transmitted through the air gap, and the sensor? ! 'l: In the wireless power transmission device 1 of this embodiment that receives detection data from By inserting the capacitor E, the air gap becomes wider and the current flowing through the switching means does not increase. Therefore, since the current flowing is smaller, the current capacity of the switching means can be reduced, and the heat sink is also smaller, so the heat sink can be made smaller.

Next, FIG. 8 shows a cross-sectional view of a coupler including the power transmitting coil A, power receiving coil B, oscillating coil 460, etc. shown in FIG. 1.

FIG. 8 shows two cylindrical couplers 10, 20, each disposed facing each other on a concentric axis. .20
have the same structure.

That is, fixed side holder 11.2 of coupler 10.20
Ferries 1 to cores 12 and 22 are inserted into the opposite sides of the cores 1 and 1, respectively. An annular groove is formed in the core 12, 22 of the flywheel 1, and a power transmitting coil, a power receiving coil B, and an oscillating coil 46D are fitted into the groove in a coaxial manner. These power transmission coil A, oscillation coil 46D
The terminals of the power receiving coil B and the terminals of the power receiving coil B are collectively pulled out from the coupler 10.20 through the lead wire 16.26 to facilitate connection with external equipment. When the two couplers 10.20 are installed very close to each other, for example, when the diameter is less than 3 (mm), the oscillating coil 46D, the power transmitting coil, and the power receiving coil B
When a current is passed through, a magnetic path as shown by the dotted line in the figure is formed, and the two couplers 10 and 20 exhibit strong magnetic coupling. Therefore, if an excitation current is passed through one of the coils of the coupler 10.20 when they are very close to each other, a magnetic field proportional to the excitation current is generated in the other coil, which transmits power and signals wirelessly. This makes it easy to send and receive information.

Next, FIG. 9 shows an example in which this embodiment is applied to an industrial turntable.

This industrial turntable rotates the table 110 by 180 degrees using a drive unit 120 to alternately transport workpieces 100 from the U-loading side to the processing side where processing is performed using a drill 105 or the like. Then, power is sent to the position sensor 130 for determining whether the workpiece 100 is placed on the table 110 at a predetermined position, and a detection signal from the position sensor 130 is received. The wireless power transmission device 1 of this embodiment is used for this purpose. Above table 11
Two power receiving side couplers 20 each having a power receiving coil B are provided on the lower surface of the power receiving coil B symmetrically with respect to the rotation center axis TC. Both couplers 20 are each connected to a power receiving unit 1b including power receiving power supply means F and the like. The power receiving unit 1b is connected to a position sensor 130, and detects the position of the workpiece 100 on the transfer side on the table 110 using the coupler 20 and the power transmitting coupler provided on the transfer side. 10 to the power transmission side unit 1a. Therefore, in the industrial turntable to which this embodiment is applied, the workpiece 1 on the transfer side of the table 110 is
The position of 00 is detected without contact.

[Effects of the Invention] As described above in detail with reference to the embodiments, in the wireless power transmission device of the present invention, when the power transmission coil and the power reception coil are in a steady power transmission gap, the power transmission frequency is set between the power transmission coil and the power reception coil. A resonant capacitor having a capacitance that resonates in parallel with is connected in parallel to the switching means. Therefore, when the gap between the power transmitting coil and the power receiving coil becomes wider than the steady power transmitting gap, the current flowing through the switching means decreases. As a result, in a device in which the gap between the power transmitting coil and the power receiving coil is variable, an increase in the current capacity of the switching means is prevented, and an increase in the amount of heat dissipated from the switching means is also prevented. Therefore, the switching means, e.g.
1 - The capacity of the transistor can be reduced, and the radiator can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 and FIG.
4 is a diagram illustrating a detailed explanation of the present invention, FIG. 4 is a configuration diagram of a conventional column, FIG. 5 is a graph showing operating characteristics of the conventional example, and FIG. 6 is a configuration diagram illustrating the configuration of the present invention. FIG. 7 is a graph showing the operating characteristics of the present invention, FIG. 8 is a cross-sectional view of a coupler used in an embodiment of the present invention (74 diagram), FIG. 9 is a configuration diagram of a device to which the embodiment is applied, and FIG. It is an explanatory diagram of a conventional example. A... Power transmission = 1 Il B... Power receiving coil C... Power source D... Switching means E... Resonant capacitor F... Power receiving power supply means G...・Sensor group 1-1...Signal transmitting means ■...Signal receiving means

Claims (1)

[Scope of Claims] A switching means connected to one end of a power transmitting coil and for intermittent current flowing through the power transmitting coil at a power transmission frequency; and a power receiving coil for transmitting and receiving power through a variable air gap with the power transmitting coil. In the wireless power transmission device equipped with the above, further, when the gap between the power transmitting coil and the power receiving coil is a steady power transmission gap in which power is transmitted and received in a steady state, an electrostatic charge that resonates in parallel to the power transmission frequency between the power transmitting coil and the power receiving coil is provided. A wireless power transmission device characterized in that a capacitance resonant capacitor is connected in parallel to the switching means.