JP2007110842A - Noncontact feeder system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noncontact feeder system by a simple and inexpensive circuit which prevents an output voltage fluctuation from exceeding its allowable value even if an ambient temperature largely changes. <P>SOLUTION: This noncontact feeder system includes a pick-up coil 5 for supplying a magnetic fields generated in a feeder 4 to a load 8 as a feeding voltage by electromagnetic induction, a resonant capacitor 60 connected in parallel with the pick-up coil 5, and a saturable reactor 61 connected in parallel with the pick-up coil 5 for inhibiting a rise in feeding voltage at no load or under light-load conditions. The coil of the saturable reactor 61 is formed of a center tap 62 and a temperature switch circuit 63 for short-circuiting the center tap 62 when the saturable reactor 61 is at a predetermined temperature or lower. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a non-contact power feeding device, and more particularly to a non-contact power feeding device that suppresses a peak voltage with a saturable reactor and stably feeds a voltage supplied to a load at a voltage equal to or lower than an upper limit allowable for the load. Is.

The non-contact power supply device, for example, is a device that supplies power to a moving body in a non-contact manner using electromagnetic induction action, does not generate sparks, does not generate dust due to wear, and does not receive an electric shock because the power supply line is an insulated cable. Features such as maintenance-free use.
Taking advantage of this, for example, it can be suitably used in a transport device in a clean room such as a semiconductor factory, a place where maintenance is difficult in high places and narrow places, and where there is a risk of electric shock due to water droplets etc. .

As an example, as shown in Patent Document 1, a pair of reciprocating conductors laid in parallel is used as a ground primary power supply line, and a receiving coil in which a coil is wound around the center leg of an E-type core is used as a secondary side. There has been proposed a non-contact power feeding device that transmits power to a power receiving coil by electromagnetic induction with a magnetic field generated by a high-frequency current flowing through an electric wire.
In this non-contact power feeding device, the secondary circuit of the power receiving coil has a resonant capacitor and a saturable reactor connected in parallel to the power receiving coil. When the resonant circuit voltage rises to a value at which the core of the saturable reactor is magnetically saturated and the core is saturated, the relative magnetic permeability (μ / μ ₀ ) of the core is almost equal to the value inherent to the magnetic material of the core (approximately 2000 to 4000). The inductance of the saturable reactor also decreases in proportion to the magnetic permeability.
In a saturable reactor, in a region where it is not saturated, the inductance is several tens of mH with respect to the winding resistance (approximately 1Ω or less), and the current phase is delayed by approximately 90 degrees with respect to the voltage phase.
As a result, a saturation current flows through the saturable reactor when the voltage is near zero within one cycle of high-frequency alternating current, and the resonant circuit is short-circuited. Thereby, the no-load voltage of the resonance circuit is suppressed, and the reactive current flowing through the no-load resonance circuit is also controlled.

By the way, the saturation magnetic flux density of the saturable reactor is an inherent value determined by the material characteristics. Generally, in the case of a ferrite material, the saturation magnetic flux density has a negative temperature coefficient and the temperature rises from about 0 ° C. to about 100 ° C. Decrease by around 30%. For this reason, when the voltage is stabilized only by the saturable reactor, it is necessary to set the saturation voltage in consideration of the temperature characteristics.
When the temperature rises due to self-heating during operation, it is possible to limit the temperature rise by heat dissipation means such as a cooling fan, but when starting from a long-time stop state, the saturable reactor is affected by the ambient temperature. The temperature, that is, the saturation voltage varies.
If the upper limit temperature at which the temperature rise is saturated is set to 80 ° C to 90 ° C and the saturation voltage is set at the rated voltage ± 10%, if the ambient temperature is 0 ° C to 40 ° C and the operating environment is used, it is saturated when starting near 0 ° C. There is a problem that the magnetic flux density becomes high, an overvoltage exceeding the withstand voltage of the circuit element may be generated and the element may be destroyed, and an expensive high withstand voltage element is used and the voltage needs to be adjusted.
Japanese Patent No. 3551304

  In view of the problems of the above-described conventional non-contact power feeding device, the present invention provides a non-contact power feeding device in which the output voltage fluctuation does not exceed an allowable value even if the outside air temperature fluctuates greatly by a simple and inexpensive circuit. The purpose is to provide.

  In order to achieve the above object, a contactless power feeding device of the present invention includes a pickup coil that feeds a load with a magnetic field generated in a feeder line as a feeding voltage by electromagnetic induction, a resonance capacitor connected in parallel with the pickup coil, and a pickup In a non-contact power feeding device that is connected in parallel with a coil and has a saturable reactor that suppresses an increase in the feeding voltage at no load or light load, an intermediate tap is provided on the coil of the saturable reactor, and the saturable reactor is predetermined. A temperature switch circuit for short-circuiting the intermediate tap when the temperature is lower than the temperature is provided.

  In this case, the temperature switch circuit can be configured using bimetal.

According to the contactless power feeding device of the present invention, a pickup coil that feeds a load with a magnetic field generated in a feeder line as a feeding voltage by electromagnetic induction, a resonant capacitor connected in parallel with the pickup coil, and a pickup coil connected in parallel. In a non-contact power feeding device having a saturable reactor that suppresses an increase in feeding voltage at no load or light load, an intermediate tap is provided on the coil of the saturable reactor, and the saturable reactor is below a predetermined temperature. Since the temperature switch circuit for short-circuiting the intermediate tap is provided, the increase in the magnetic permeability can be canceled by short-circuiting the intermediate tap when the saturable reactor falls below a certain temperature. However, the output voltage fluctuation can be prevented from exceeding the allowable value.
As described above, the non-contact power feeding device of the present invention includes means for suppressing output voltage fluctuation due to a temperature change within an allowable value, so that not only a clean room where the temperature of the installation site is kept constant, but also a general There is an effect that the non-contact power feeding apparatus can be stably operated without causing a failure due to overvoltage without special adjustment or the like in a factory or a warehouse.

  In addition, it is common practice to use a voltage detection circuit and a semiconductor element such as an FET to achieve a constant voltage, but the temperature switch circuit is made of bimetal so that there is no power supply in the circuit. However, the purpose can be realized at low cost simply by adding a simple switch and wiring to the conventional device.

Hereinafter, embodiments of the non-contact power feeding device of the present invention will be described with reference to the drawings.
When the core size and frequency are constant, the generated voltage of the coil is proportional to the magnetic flux and the number of turns of the coil, the magnetic flux is proportional to the number of turns of the coil and the magnetic permeability, and the inductance is proportional to the permeability and the square of the number of turns. By changing the number of turns, the generated voltage can be set to the saturation voltage at that temperature.
Then, if the winding is wound N times on the iron core having the magnetic path cross-sectional area S and the length h of the magnetic circuit, and the maximum current I flowing through the coil and the current i = 2 ^1/2 Isinωt flowing through the coil, the magnetic flux in the iron core is It changes with time, and induces an induced voltage e shown in Equation (1) in the winding.
e = −Ndφ / dt = (− μSN ² ω / h) 2 ^1/2 Icos ωt (1)
L = μSN ² / h (2)
Here, e: induced voltage, N: number of coil turns, φ: magnetic flux, h: magnetic path length, S: magnetic path cross-sectional area, ω: 2πf, L: inductance, μ: permeability.
The non-contact power feeding device of the present invention can use this fact to cancel the increase in magnetic permeability by providing an intermediate tap on the coil and short-circuiting the intermediate tap when the temperature falls below a certain temperature.
If bimetal is used for the short-circuit switch, a circuit can be formed even when the power supply is stopped.
Of course, it is also possible to detect the temperature with a temperature sensor and connect the load circuit after short-circuiting the intermediate tap of the coil using a timer or the like at the time of activation.

In FIG. 1, the whole structure of a non-contact electric power feeder is shown.
Reference numeral 1 denotes an insulation transformer for receiving commercial power, and the secondary side is connected to the high-frequency inverter 2 via a switch. The high-frequency inverter 2 is a constant current inverter, and causes a set frequency and a constant current to flow through the feeder line 4 regardless of the increase or decrease of the load.
A resonance capacitor 3 is used for tuning the feed line and the load impedance.
The feeder 4 is laid along the conveyance path so as to form a pair of reciprocating conductors on the left and right in the left and right grooves of the E-shaped core of the pickup coil 5.
Reference numeral 5 denotes a pickup coil in which a coil is wound around the center leg of the E-type core. The pickup coil 5 receives a magnetic flux (induced voltage) by receiving a magnetic flux generated by a high-frequency current flowing through the feeder line 4.

As shown in FIG. 2, the resonance unit 6 includes a capacitor 60 and a saturable reactor 61. The pickup coil 5 and the capacitor 60 form a resonance circuit. The output of this power reception circuit is rectified by the rectifier circuit 7 and output to the load 8.
And in the non-contact electric power feeder of a present Example, while providing the intermediate tap 62 in the coil of the saturable reactor 61, the temperature switch circuit 63 which short-circuits this intermediate tap 62 when a saturable reactor is below predetermined temperature is provided. Yes.
The temperature switch circuit 63 is configured using bimetal.

As shown in FIG. 4, when the saturation magnetic flux density of the saturable reactor changes linearly from 560 mT at 0 ° C. to 400 mT at 90 ° C., for example, the outside air temperature is 15 ° C. by the non-contact power feeding device of this embodiment. When operating under the condition that the reactor temperature is saturated at 55 ° C., the saturation magnetic flux density is about 462 mT by proportional calculation.
When the outside air temperature rises to about 40 ° C., the reactor temperature of the saturable reactor rises by about 40 ° C., which is about the same difference as 15 ° C. → 55 ° C., so it rises to about 80-81 ° C. and the saturation magnetic flux density is 10 % Decrease to about 416 mT.
(62 × (90−81) ÷ (90−55) + 400≈416)
As a result, the saturation voltage is also reduced by about 10%. Conversely, when the outside air temperature decreases and the temperature of the saturable reactor reaches about 29-30 ° C., the saturation voltage increases by about 10% compared to 55 ° C.
When the temperature further decreases and the core temperature of the saturable reactor reaches about 0 ° C., the saturation voltage rises by about 10% from that at 30 ° C. When the operation starts at 0 ° C., the generated voltage is higher than at 55 ° C. About 21% higher (1.1 × 1.1 = 1.21).
In order to limit the generated voltage at 0 ° C. to a 10% increase in the generated voltage at 55 ° C., the generated voltage at 55 ° C. is used as a reference voltage. do it.
Therefore, by providing the intermediate tap 62 with the number of coil turns reduced by about 5% according to the relationship (e∝N ² ) of the above-described formula (1), a voltage about 10% lower can be taken out, so the saturation voltage is reduced by 10%. (0.95 × 0.95≈0.9).
Then, until the temperature of the core reaches about 30 ° C. by operation, it is possible to suppress a large fluctuation in the output voltage by short-circuiting with a bimetal temperature switch circuit (temperature relay) 63 or the like.

Thus, the contactless power supply device of the present embodiment includes a pickup coil 5 that supplies a magnetic field generated in the power supply line 4 to the load 8 as a power supply voltage by electromagnetic induction, and a resonance capacitor 60 that is connected in parallel with the pickup coil 5. In a non-contact power feeding device including a saturable reactor 61 that is connected in parallel with the pickup coil 5 and suppresses an increase in power feeding voltage at no load or light load, an intermediate tap 62 is provided on the coil of the saturable reactor 61, Since the temperature switch circuit 63 for short-circuiting the intermediate tap 62 when the saturable reactor 61 is below a predetermined temperature is provided, the permeability can be increased by short-circuiting the intermediate tap 62 when the saturable reactor 61 falls below a certain temperature. The output voltage fluctuation exceeds the allowable value even if the outside air temperature fluctuates greatly. It can be so no.
As described above, the non-contact power feeding device of the present invention includes means for suppressing output voltage fluctuation due to temperature change within an allowable value, so that not only a clean room where the temperature of the installation site is kept constant but also a general There is an effect that the non-contact power feeding apparatus can be stably operated without causing a failure due to overvoltage without special adjustment or the like in a factory or a warehouse.
In addition, a constant voltage is generally realized by using a voltage detection circuit and a semiconductor element such as an FET, but the circuit has no power supply by forming the temperature switch circuit 63 using bimetal. The objective can be realized at low cost simply by adding a simple switch and wiring to the conventional device.

  As mentioned above, although the non-contact electric power feeder of this invention was demonstrated based on the Example, this invention is not limited to the structure described in the said Example, The structure described in the said Example is combined suitably, etc. The configuration can be changed as appropriate without departing from the spirit of the invention.

  The contactless power supply device of the present invention has a characteristic that the output voltage fluctuation does not exceed the allowable value even if the outside air temperature fluctuates greatly by a simple and inexpensive circuit. It can be used not only for a maintained clean room, but also for non-contact power supply devices used in general factories and warehouses, for example.

It is the whole lineblock diagram showing one example of the non-contact electric supply device of the present invention. It is a circuit diagram which shows the principal part of the non-contact electric power feeder. It is an outline view showing a saturable reactor provided with an intermediate tap. It is a graph which shows an example of the relationship between a saturation magnetic flux density and temperature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transformer 2 High frequency inverter 3 Tuning capacitor 4 Feeding line 5 Pickup coil (receiving coil)
60 Resonant Capacitor 61 Saturable Reactor 62 Saturable Reactor Intermediate Tap 63 Temperature Switch Circuit 7 Rectifier Unit 8 Load

Claims (2)

  A pickup coil that feeds a load with a magnetic field generated in the feeder line as a feeding voltage by electromagnetic induction, a resonant capacitor connected in parallel with the pickup coil, a parallel connection with the pickup coil, In a non-contact power feeding device equipped with a saturable reactor that suppresses the rise, a temperature switch circuit is provided that short-circuits the intermediate tap when the saturable reactor is below a predetermined temperature, as well as providing an intermediate tap on the coil of the saturable reactor. A non-contact power feeding device characterized by that.   2. The non-contact power feeding apparatus according to claim 1, wherein the temperature switch circuit is configured using bimetal.

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