JP3650694B2 - Contactless power supply method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-contact power feeding method, in particular, a threshold voltage at which an inductance transition occurs in an inductor is determined by the magnitude of the load current to ensure the maximum load output obtained by the circuit system and the load current can be greatly changed. The present invention relates to a non-contact power feeding method in which fluctuations in terminal voltage are reduced.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a member or component in a manufacturing process of a semiconductor, liquid crystal, or the like is required to be performed in a clean environment set in order to increase the accuracy of a product. In the transport process, when power is supplied from the power supply line to the transport carriage, dust is generated due to contact between the power supply line and the current collector.
In order to prevent this, the primary side conductor (feeding line) connected to the power source is arranged on the fixed side along the traveling path of the transport carriage, and the current flowing through the primary side conductor is placed on the transport vehicle side. A conveyance system has been proposed in which a non-contact power supply device for supplying electric power in a non-contact manner is provided, and thereby, necessary power can be supplied to the conveyance vehicle side without generating dust using an electromagnetic induction phenomenon. .
[0003]
In this clean transfer system, in order to supply power with a non-contact power supply device mounted on a traveling transport vehicle, as shown in FIG. 3, a magnetic flux generated by a reciprocating current flowing through the primary side conductors 1a and 1b is used as an iron core. Lead to 3. Since the primary current is a high-frequency alternating current, the magnetic flux guided to the iron core 3 changes alternately, and a voltage is applied to the winding 2 of the secondary pickup coil wound around the iron core 3 due to an electromagnetic induction phenomenon. Induced.
As shown in the circuit diagram of FIG. 4, the pickup coil is connected in series with a capacitor C ₂ to compensate for the reactance ωL ₂ of the winding of the pickup coil, and the negative reactance-1 / (ωC ₂ ) leave the state close to the resonance, to generate a predetermined voltage across the capacitor C _2. Connecting the load 8 at both ends of the capacitor C _2, to obtain a current of the load 8 by utilizing this predetermined voltage.
[0004]
The synthetic reactance X of the series circuit is X = ωL ₂ −1 / (ωC ₂ )
X = 0 corresponds to so-called series resonance. At this time, a large voltage can be applied to the terminal of the load with a small number of inputs, but since the fluctuation when deviating from the equilibrium point is large, it is usually close to series resonance, but contactless power feeding is performed with some synthetic reactance X remaining. Do.
[0005]
[Problems to be solved by the invention]
The conventional non-contact power feeding method, that is, the circuit shown in FIG. 4 has a characteristic that the terminal voltage of the load decreases as the load current increases as shown in FIG. Therefore, in order to keep load voltage fluctuations within an allowable range with respect to changes in load current caused by driving the motor of a transport vehicle, the load current that can be passed is restricted, or the alternating current obtained by the pickup coil is converted to direct current. However, there is a problem that an expensive voltage stabilization function must be added to the direct current power source.
[0006]
The present invention solves the problems of the conventional non-contact power feeding method described above, determines the threshold voltage at which the inductance transition in the inductor occurs based on the magnitude of the load current, and secures the maximum load output obtained in the circuit system. An object of the present invention is to provide a non-contact power feeding method in which fluctuation of the load terminal voltage is small even when the load current is greatly changed.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the non-contact power feeding method of the present invention uses a power feeding line connected to a power source as a primary side conductor, and uses the electromagnetic induction phenomenon from the current flowing in the primary side to the secondary side. In a non-contact power feeding method in which a load is connected to both ends of a capacitor connected to the pickup coil so as to take electric power in a non-contact manner by the pickup coil and compensate for the reactance of the pickup coil, When an inductor whose inductance changes nonlinearly according to the magnitude of the threshold voltage is connected, and the terminal voltage of the load becomes a voltage larger than the threshold voltage, the resonance point is shifted using the inductance transition of the inductor. , it is possible to suppress the increase of the load terminal voltage, maximum a threshold voltage of the inductor depends from the circuit system load Characterized in that as substantially equal to the load terminal voltage in the value of the load current as a force.
[0008]
The non-contact power feeding method of the present invention having the above configuration ensures the maximum output possible by the system and provides load voltage characteristics with less fluctuation with respect to a wider load current change.
[0009]
In order to achieve the same purpose, the feeder line connected to the power source is used as the primary conductor, and the current flowing through the primary side is used to make contactless by the secondary side pickup coil using the electromagnetic induction phenomenon. In a non-contact power feeding method in which a load is connected to both ends of a capacitor connected to the pickup coil so as to compensate for the reactance of the pickup coil, the magnitude of the threshold voltage is applied to both ends of the load. When an inductor whose inductance changes nonlinearly is connected and the terminal voltage of the load becomes a voltage larger than the threshold voltage, the inductance transition of the inductor is used to shift the resonance point and increase the load terminal voltage. In addition, the threshold voltage of the inductor is set to 70 to 75 percent of the load short-circuit current determined by the circuit system. Wherein the in the value of the load current of the cement was set to approximately equal to the load terminal voltage.
[0010]
The non-contact power feeding method of the present invention having the above-described configuration secures the maximum output possible by the system using only the value of the load short-circuit current that can be measured and calculated by a simpler and more straightforward method, and more The present invention provides load voltage characteristics with little fluctuation with respect to a wide load current change.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the non-contact power feeding method of the present invention will be described with reference to the drawings.
[0012]
The present invention relates to a non-contact power feeding method mounted on a movable transport vehicle in a clean transport system. As shown in FIG. 3, a magnetic flux generated by a reciprocating current flowing in primary conductors 1a and 1b. To the iron core 3. A magnetic flux generated by a primary current, which is a high-frequency alternating current, is guided to the iron core 3, and a voltage is induced in the winding 2 of the secondary pickup coil wound around the iron core 3 by an electromagnetic induction phenomenon. As shown in FIG. 4 which is a circuit diagram of the pickup coil, in order to compensate for the reactance ωL ₂ of the winding of the pickup coil, a capacitor C ₂ is connected in series with the pickup coil and its negative reactance−1 / (ωC ₂ ). leave the state close to the resonance gives the required voltage across the capacitor C _2. Connecting the load 8 at both ends of the capacitor C _2, to obtain a current of the load 8 by utilizing this required voltage.
[0013]
The synthetic reactance X of the series circuit is given by the following formula: X = ωL ₂ −1 / (ωC ₂ ) (1)
X = 0 corresponds to so-called series resonance. At this time, a large voltage can be applied to the terminal of the load with a small number of inputs, but since the fluctuation when deviating from the equilibrium point is large, it is usually close to series resonance, but contactless power feeding is performed with some synthetic reactance X remaining. Do.
[0014]
In the circuit shown in FIG. 4 alone, as shown by the solid line in FIG. In order to reduce the variation of the load voltage characteristics for the load current, as shown by a dotted line in FIG. 2, the series circuit of the pickup coil and a capacitor C ₂ at a small load current the terminal voltage increases in the present invention from the resonance condition in large shifting purposes, for example, the circuit diagram as shown in FIG. 5, in parallel with the capacitor C ₂ and the load, connecting the inductor Lt whose inductance varies nonlinearly with the magnitude of the voltage.
As shown in FIG. 6, this inductor retains a sufficiently large inductance in a voltage range lower than the required threshold voltage Ect, and the non-linearity in which the inductance rapidly decreases with respect to a voltage higher than the required threshold voltage Ect. It has the inductance characteristic. An inductor having such a non-linear inductance characteristic has a structure in which a winding is wound around a ring-shaped iron core, and a desired non-linear inductance characteristic is realized using the magnetic saturation characteristic of the iron core.
[0015]
The terminal voltage of the load, thus when lower than the threshold voltage Ect the terminal voltage of the inductor connected in parallel with the capacitor C ₂ and these transition inductance value in the inductor described above to occur, the inductor as shown in FIG. 6 the inductance is sufficiently large regarded as open with the capacitor C _2, synthetic reactance X by the pickup coil and a capacitor C ₂ is close to the resonance is maintained at a small negative value.
However, when the load current decreases and the terminal voltage of the load increases as shown by the solid line in FIG. 2, the inductance of the inductor connected in parallel with the load decreases rapidly, and the capacitance C ₂ of the capacitor as viewed from the pickup coil. , The combined reactance X by the pickup coil and the capacitor C ₂ set close to the resonance becomes a large negative value, greatly deviates from the resonance, reduces the current flowing through the capacitor C ₂ , and reduces the load terminal voltage. Is suppressed as shown by the dotted line in FIG.
[0016]
The present invention relates to a method for determining a threshold voltage Ect at which an inductance value transition occurs in an inductor.
FIG. 1 shows how to determine the threshold voltage Ect at which the transition of the inductance value occurs in the inductor according to the present invention.
As shown in FIG. 4, when an inductor having a nonlinear inductance characteristic is not in parallel with the load, the load terminal voltage decreases with 1-3′-d and the load current in FIG. As the load current increases, the load output changes to a mountain shape such as oa′-abcd, and when the load current becomes Ipm, the load output takes a maximum value Pmax at a point b on the mountain curve.
[0017]
In the present invention, as shown in FIG. 5, an inductor Lx whose inductance changes nonlinearly with the magnitude of the voltage is connected in parallel with the capacitor and the load, and the inductance value is changed as shown in FIG. The threshold voltage Ect at which the transition occurs is substantially equal to the load terminal voltage 3 ′ at the load current value at which the load determined by the circuit system is the maximum output. As shown in FIG. 4, when an inductor having a nonlinear inductance characteristic is not connected in parallel with the load, the load terminal voltage and the load output characteristic with respect to the load current shown in FIG. Can be identified.
[0018]
If the circuit constants in FIG. 4 are known, the load terminal voltage and the load output characteristic with respect to the load current shown in FIG. 1 can also be specified by solving an AC circuit equation using complex numbers. Therefore, the threshold voltage Ect at which the transition of the inductance value occurs in the inductor connected in parallel with the load is the load terminal voltage 3 ′ at the load current value at which the load determined by the circuit system is the maximum output as in the present invention. It is feasible to choose to be approximately equal.
[0019]
Further, based on the experience of measurement and calculation analysis on the non-contact power feeding device that is practically used, the load current value at which the load becomes the maximum output is 70 of the load current (Is in FIG. 1) at which the load voltage becomes zero. It has been found to be ~ 75 percent. Therefore, in another embodiment of the present invention, the load terminal voltage is set equal to 70 to 75% of the load short-circuit current Is determined by the circuit system. According to this method, the load output characteristic over the entire range of the load current change is unnecessary, and the threshold voltage Ect at which the transition of the inductance value occurs in the inductor connected in parallel with the load is determined only from the load short-circuit current Is. Can do. The magnitude of the load short-circuit current determined by the circuit system can be obtained by actual measurement and calculation using a simpler and more straightforward method.
[0020]
The reason why the threshold voltage Ect is substantially equal to the load terminal voltage at the load current value at which the load determined by the circuit system is the maximum output will be clarified with reference to FIG.
In the present invention, the threshold voltage Ect at which the inductance value transition occurs in the inductor connected in parallel with the load is substantially equal to the load terminal voltage 3 ′ at the load current value Ipm at which the load determined by the circuit system is the maximum output. I have to.
[0021]
Therefore, according to the present invention, the load terminal voltage is 3-3′-d and the load output is obd-d as the load current increases, and the maximum output Pmax that the circuit system can provide as the load output is obtained. However, if the threshold voltage Ect in the inductor is 4 ', the flat load voltage range is 4-4', which is wider than 3-3 'in the present invention, but the load output characteristic is oc-d. The maximum output Pmax allowed by the circuit system is not reached, which is not preferable.
Further, when the threshold voltage Ect is 2 ′, the load output characteristic is oa-b-d, and the maximum output Pmax that the circuit system can provide is secured, but the flat load voltage range is 2-2 ′. It becomes narrower than 3-3 ′ in the case of the present invention, which is not preferable.
[0022]
【The invention's effect】
According to the non-contact power feeding method of the present invention, the maximum output that the circuit system is capable of is ensured by determining the threshold voltage at which the inductance value transition occurs in the inductor connected in parallel with the load as in the present invention. Therefore, it is possible to provide a non-contact power feeding device having a wide flat load voltage range with little variation with respect to a change in load current.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a method for determining a threshold voltage of an inductor, showing an embodiment of a non-contact power feeding method of the present invention.
FIG. 2 is a current / voltage characteristic diagram of a load in a conventional non-contact power feeding device.
FIG. 3 is a front sectional view of the non-contact power feeding device.
FIG. 4 is a circuit diagram of a conventional non-contact power feeding device.
FIG. 5 is a circuit diagram in which an inductor having a nonlinear inductance characteristic is connected in parallel with a load in the embodiment of the non-contact power feeding method of the present invention.
6 is a characteristic diagram showing nonlinear inductance characteristics of the inductor in FIG. 5. FIG.
FIG. 7 is an explanatory diagram for explaining the effectiveness of the present invention.
[Explanation of symbols]
V ₁ Primary power supply terminal voltage I ₁ Current flowing through the primary side conductor M Mutual inductance between the primary side conductor and the secondary side pickup coil C ₂ Capacitance of the capacitor connected in series with the reactance L ₂ L ₂ Inductance of secondary pickup coil Is Load short-circuit current Ipm Load current that maximizes load output Pmax Maximum load output 1a Primary conductor 1b Primary conductor 2 Pickup coil 3 Iron core 5 Pickup coil 7 Series capacitor for reactance compensation of pickup coil 8 load

Claims (2)

Using the feeder connected to the power source as the primary conductor, the electric current is taken from the primary side using the electromagnetic induction phenomenon by the secondary side pickup coil in a non-contact manner, and the pickup coil In a non-contact power feeding method in which a load is connected to both ends of a capacitor connected to the pickup coil so as to compensate for reactance, an inductor whose inductance changes nonlinearly depending on the magnitude of the threshold voltage is connected to both ends of the load. When the terminal voltage of the load becomes a voltage larger than the threshold voltage, the inductance transition of the inductor is used to shift the resonance point , thereby suppressing the increase of the load terminal voltage and the threshold voltage of the inductor. Is approximately equal to the load terminal voltage at the load current value that is the maximum load output determined by the circuit system. Non-contact power feeding method is characterized in that so as to. Using the feeder connected to the power source as the primary conductor, the electric current is taken from the primary side using the electromagnetic induction phenomenon by the secondary side pickup coil in a non-contact manner, and the pickup coil In a non-contact power feeding method in which a load is connected to both ends of a capacitor connected to the pickup coil so as to compensate for reactance, an inductor whose inductance changes nonlinearly depending on the magnitude of the threshold voltage is connected to both ends of the load. When the terminal voltage of the load becomes a voltage larger than the threshold voltage, the inductance transition of the inductor is used to shift the resonance point , thereby suppressing the increase of the load terminal voltage and the threshold voltage of the inductor. At a load current value of 70 to 75 percent of the load short-circuit current determined by the circuit system. Non-contact power feeding method is characterized in that so as to substantially equal to the terminal voltage.

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