JPH08251843A - Non-contact power supply device - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to adjust the feeder current of a contactless power feeder according to the load power without adding a new device to the pickup side circuit. [Structure] The loss of the power supply line 2 is calculated by the power supply line loss calculation circuit 20, the input power of the high frequency AC power supply 1 is calculated by the power supply input power calculation circuit 16, or the output power is calculated by the power supply output power calculation circuit 11.
Calculate with. The subtracter 24 calculates the sum P _{2T of the} load powers from the difference between the input power and the feeder loss or the difference between the output power and the feeder loss. On the other hand, the subtractor 31 has (n-1)
Calculate P _TH from the difference between P _2min and P _2T and _limit it to 3
2 and the gain 33 to set the current command value, and the current regulator 3
5 controls the current of the power supply line 2 appropriately by controlling I ₁ to match the current command value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to contactless power supply for supplying electric power from a high frequency AC power source to a load which is separately connected via a plurality of pickup coils magnetically coupled to a conductor. Regarding the device.

[0002]

2. Description of the Related Art FIG. 7 is a main circuit connection diagram showing a conventional example of a contactless power supply device. In the conventional circuit shown in FIG. 7, reference numeral 1 is a high frequency AC power supply capable of adjusting an output current. Reference numeral 2 denotes a conductor (hereinafter referred to as a power supply line) in which one conductive wire having an insulating coating is folded back and arranged in parallel at a constant interval, and is connected to the high frequency AC power supply 1. The high frequency AC power supply 1
For example, power is supplied from an external power source such as a commercial power system. Reference numeral 3 is a pickup coil which is magnetically coupled to the feeder line 2. A voltage regulator 4 is connected to the rear stage of the pickup coil 3, and a load 5 is connected to the rear stage of the voltage regulator 4. These pickup coils 3,
The voltage adjusting device 4 and the load 5 are collectively referred to as a pickup side circuit 6, and in the non-contact power supply device, a plurality of pickup side circuits 6 are provided in the power supply line 2, and power is simultaneously supplied to each of these pickup side circuits 6. Can be supplied.

With the above-mentioned structure, when a high frequency AC current having a sinusoidal waveform (or a waveform similar to a sinusoidal wave) is passed from the high frequency AC power source 1 to the feeder line 2, the pickup coil 3
A voltage is generated at both ends of the by electromagnetic induction. The voltage adjusting device 4 converts the voltage generated across the pickup coil 3 into a predetermined voltage and supplies electric power to the load 5. By the above operation, electric power can be transmitted from the high frequency AC power supply 1 to the load 5 in a contactless manner. Since the power supply line 2 is laid along the direction in which the pickup coil 3 moves, it is possible to transfer power from any place of the power supply line 2 to the pickup side circuit 6 in a contactless manner.

FIG. 8 is an explanatory circuit diagram for explaining the operation of non-contact power transmission by the non-contact power feeding device. In this explanatory circuit diagram, the effective value of the current of the feeder line 2 is I ₁ . Here, for example, if a capacitor is connected inside the voltage regulator 4 in parallel with the input terminal and the capacitor resonates with the pickup coil 3 and the frequency of the feed line current, the pickup coil 3 of the feed line 2 and A voltage having the same phase as the current of the power supply line 2 is generated in the magnetic coupling portion. The effective value of this voltage is V ₁ . If the effective value of the voltage generated at both ends of the pickup coil 3 is V ₂ , this V ₂ is V
Proportional to ₁ . Further, the electric power transmitted from the voltage regulator 4 to the load 5 is P ₂ . Pickup coil 3 here
2 and the loss of the voltage adjustment device 4 are so small that they can be ignored, the power transmitted from the power supply line 2 to the pickup coil 3 and the above-mentioned P ₂ match in a steady state.
If these are arranged, the following formulas 1 and 2 are established. However, K is a proportional constant.

[0005]

[Equation 1] V ₁ = K · V ₂

[0006]

[Equation 2] The maximum value of P ₂ = I ₁ · V ₁ V ₂ is the performance of the voltage regulator 4 (for example, the breakdown voltage of the internal semiconductor switch element, the switching duty ratio)
Limited by Therefore, V ₁ also has the maximum value according to the above-mentioned formula 1. When the maximum value of V ₁ is V _1max and the maximum value of V ₂ is V _2max , the following formula 3 is established.

[0007]

[ _Expression 3] V _1max = K · V _2max On the other hand, if the maximum value of P ₂ is P _2max , the load power is P
_At the time of _2max , according to the equations 2 and 3, I ₁ should be equal to or more than the value I _1max defined by the following equation 4.

[0008]

To Equation 4] I _1max = P _2max / V _1max plurality of pickup side circuit 6, because it is providing power from the same power supply line 2, the current I ₁ is a maximum among the plurality of pickup side circuit 6 It is necessary to set a value commensurate with the load power of. However, since the non-contact power supply device has a feature of transmitting electric power in a non-contact manner, the operating conditions of the individual pickup-side circuits 6 such as the power consumption of the load and the load fluctuation are usually calculated by the operation of the high-frequency AC power supply 1. Cannot be reflected in. Therefore, each pickup side circuit 6
_Must always keep the value of the current flowing through the power supply line 2 as I _1max in order to guarantee that it can operate at the maximum load power at any time.

[0009]

However, when the maximum current is constantly applied to the power supply line 2, the power loss due to the resistance of the power supply line 2 becomes large, which not only wastes energy but also increases the efficiency of the device. Causes the inconvenience. Therefore, when the operation status of each pickup side circuit 6 is reflected in the operation of the high frequency AC power supply 1 and the feeder line current is made smaller than the maximum value, a sensor is installed in each pickup side circuit 6 and the sensor is obtained. Information high frequency AC power supply 1
Since a new transmission circuit must be provided in each pickup side circuit 6 in order to provide it to the control circuit of No. 3, an extra device is added, and the structure becomes complicated and reliability deteriorates. I will end up.

SUMMARY OF THE INVENTION It is an object of the present invention to adjust the feeder current of a contactless power feeder according to the load power without adding a new device to the pickup side circuit.

[0011]

In order to achieve the above object, a contactless power supply device of the present invention comprises a high frequency AC power supply,
A conductor connected to this high-frequency AC power supply, a plurality of pickup coils magnetically coupled to this conductor, a voltage regulator that is separately connected to each pickup coil to adjust the output voltage, and a voltage regulator. In a contactless power supply device including a load connected separately, a load power estimation calculation circuit that estimates the total power consumed by each load from various amounts detected when the high-frequency AC power supply operates, and And a current control circuit that controls the current flowing through the conductor based on the load power estimation calculation value.

The load power estimation calculation circuit includes a power supply power calculation circuit for calculating the high frequency AC power supply output power or the high frequency AC power supply input power, and a conductor loss calculation circuit for calculating a loss caused by a current flowing through the conductor. And a subtraction circuit for calculating a difference between the power supply power calculated value and the conductor loss calculated value. The current control circuit maintains a current flowing through the conductor at a constant value when the load power estimation calculation value is a predetermined value or more, and when the load power estimation calculation value is less than the predetermined value, The current flowing through the conductor is controlled so as to be reduced below the constant value.

The current flowing through the conductor is reduced by a linear function of the load power estimation calculation value or a function similar thereto.

[0014]

According to the present invention, a value obtained by subtracting the power loss of the power feeding line from the output power or the input power of the high frequency AC power source that constitutes the contactless power feeding device is the power supplied to the load via each pickup side circuit. It is assumed that there is a current, and the high-frequency AC power supply is controlled so that a current calculated from this power flows through the power supply line.

FIG. 9 is an explanatory view for explaining the principle of estimating the load power from the operating condition of the high frequency AC power supply. The names, applications and functions of the high frequency AC power supply 1, the power supply line 2 and the pickup side circuit 6 are as follows. Since it has already been described in FIGS. 7 and 8,
These explanations are omitted. It is assumed that n pickup side circuits 6 are magnetically coupled to the power supply line 2. If the load power of the first pickup side circuit 6 is P ₂₁ , the second load power is P ₂₂ , the nth load power is P _2n , and the total load power of all the pickup side circuits is P _2T , then Formula 5 is materialized.

[0016]

Equation 5] The _{P 2T = P 21 + P 22} + ····· + P 2n output voltage of the high-frequency AC power source 1 v _O, the active component P _O of the output voltage, the power supply line current i _1, the frequency f Then,
The following Equation 6 is obtained.

[0017]

(Equation 6)

Since P _O is the sum of P _2T and the conduction loss in the power feeding line 2, Equation 7 holds in the steady state. However, R is the resistance value of the power supply line 2.

[0019]

Equation 7] _{P 2T = P O -R · I} 1 2 In other words, if known resistance value R of the power supply line 2 detects the output voltage v _O of the feeder current i ₁ and the high-frequency AC power source 1, these It can be seen that the total sum P _2T of the load powers can be estimated by performing the calculations of Formulas 6 and 7 using the value of. In the steady state, the input power P _IN and the output power P _{O of} the high frequency AC power supply 1 are almost equal, so even if P _IN is obtained from the input voltage v _IN and the input current i _{IN of} the high frequency AC power supply 1, P _2T is estimated. It is possible to

[0020]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, in which only a feeder line 2 connected to a high frequency AC power source 1 is shown and magnetically coupled to this feeder line 2. Illustration of the plurality of pickup side circuits 6 that are provided is omitted. In the first embodiment circuit of FIG. 1, when various data during operation of the high frequency AC power supply 1 is input to the load power estimation calculation circuit 7, the load power estimation calculation circuit 7 uses this data to sum the load power of all pickup side circuits. Estimate P _2T . The current control circuit 8 inputs the estimation calculation result in the load power estimation calculation circuit 7 and controls the current i ₁ flowing in the power supply line 2.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention, and shows the configuration of the load power estimation calculation circuit 7 shown in FIG. 1 described above. That is, the power output power calculation circuit 1
Reference numeral 1 is a multiplier 12 and a low-pass filter 13, and the voltage v _O output from the high-frequency AC power supply 1 and the output current detector 1
The product of the current i ₁ detected by 0 and the current i ₁ is calculated by the multiplier 12, and the calculation result is passed through the low pass filter 13 to the subtractor 24.
Give to. On the other hand, the feeder line loss calculation circuit 20 is composed of an effective value calculator 21, a multiplier 22 and a gain 23, and obtains the squared value of the effective value of the current i ₁ detected by the output current detector 10, and calculates the squared value. Is multiplied by R (R is the resistance value of the power supply line 2).

The subtractor 24 subtracts the calculation result of the power supply line loss calculation circuit 20 from the calculation result of the power supply output power calculation circuit 11 to estimate P _2T as the total load power of all pickup side circuits. FIG. 3 is a circuit diagram showing a third embodiment of the present invention, and shows another configuration of the load power estimation calculation circuit 7 shown in FIG. 1 described above. That is, the power supply input power calculation circuit 16 includes a multiplier 17 and a low-pass filter 18, and the product of the voltage v _IN input to the high frequency AC power supply 1 and the current i _IN detected by the input current detector 15 is multiplied by the multiplier 17. The calculation result is given to the subtractor 24 via the low-pass filter 18. On the other hand, the feed line loss calculation circuit 20 has the same configuration as that of the circuit of the second embodiment described above with reference to FIG. 2, and includes an effective value calculator 21, a multiplier 22 and a gain 23, which the output current detector 10 detects. The square value of the effective value of the current i ₁ is calculated, and the square value is multiplied by R (R is the resistance value of the power supply line 2).

The subtractor 24 subtracts the calculation result of the power supply line loss calculation circuit 20 from the calculation result of the power supply input power calculation circuit 16 to estimate the total load power of all pickup side circuits as P _2T . If the conduction loss of the power supply line 2 is so small as to be negligible, it can be considered that P _O ≈P _2T . Therefore, the power supply line loss calculation circuit 20 and the subtractor 24 shown in FIGS. 2 and 3 are omitted. can do.

FIG. 4 is a circuit diagram showing a fourth embodiment of the present invention. This fourth embodiment circuit is the second circuit of FIG.
A current control circuit portion is added to the embodiment circuit. The control rule of the current of the power supply line 2 by this current control circuit will be described below. However, in order to simplify the explanation, the maximum value of the load power of the pickup side circuit is P _2max ,
The minimum value is set to P _2min , but each pickup side circuit has the same characteristics. Therefore, the maximum values of the respective load powers are all equal and the minimum values are also the same.

It is the total load power P _2T that can be estimated from the operating condition of the high frequency AC power supply 1, and the load power of each pickup side circuit 6 cannot be known. For example, n
Half of the pickup side circuits 6 (ie, n / 2)
In There is the case that the other half at the maximum power P _2max of minimum power P _2min, power the pickup side circuit 6 corresponds to all the average value, i.e. the case of outputting a _{(P 2max -P 2min) / 2} , the high-frequency The values seen from the AC power supply 1 are the same, and the former and the latter cannot be distinguished. Therefore, the condition under which the contactless power supply device operates stably is "if the load power of even one of the pickup side circuits may be P _2max , the power supply line current is defined by I _1max That's it. " That is, the total sum P of the estimated load powers
_{When 2T} is equal to or _larger than the constant P _TH defined by the following formula 8,
It _suffices to set the power supply line current to a constant value of I _1max or more.

[0026]

Equation 8] described control _{P TH = P 2max + (n} -1) · P 2min then the P _2T reduces the feeder current is smaller than P _TH. When P _2T <P _TH , n-1
The output of each pickup side circuit is P _2min , and the remaining one may be operated with an output of P _2min or more, and the feeder current may be passed. When the value of P _2min or more is P _2M , this P _2M is given by the following formula 9.

[0027]

[Equation 9] P _2M = P _2T − (n−1) · P _2min where P _2T can be calculated by calculation, and n and P _2min
Is a known value, P _2M can be easily calculated. From the equations 2 and 3 described above, the condition of the feeder current i ₁ is the following equation 10.

[0028]

I ₁ = P _2M / V _{1max Since} V _1max is a known value, i ₁ can be determined. The current control rule described above is realized by the circuit of the fourth embodiment of FIG. That is, the subtracter 24 calculates P _2T by subtracting R · i ₁ ² calculated by the feeder loss calculation circuit 20 from P _O calculated by the power supply output power calculation circuit 11. Subtracter 31 in accordance with equation 9, from the P _2T (n
Newsletter P _2M by subtracting -1) · P _2min.
This P _2M is given by the formula 10 via the limiter 32 and the gain 33.
I ₁ is obtained by the calculation of. I ₁ output from the gain 33 becomes the current command value. The current controller 35 supplies a high-frequency AC power supply 1 with an adjusting operation signal that makes the deviation between the current command value and the current detection value i ₁ output by the effective value calculator 21 zero, and controls the current of the power supply line 2. .

FIG. 5 is a circuit diagram showing a fifth embodiment of the present invention. The current control circuit is formed by adding a current control circuit portion to the circuit of the third embodiment of FIG. 3 described above. Since the operation of the part is the same as that of the circuit of the fourth embodiment described above, the description thereof will be omitted. The circuit of the fifth embodiment estimates the load power based on the input power of the high frequency AC power supply 1. If the output power of the high frequency AC power supply 1 is used to estimate the load power, there is a disadvantage that the accuracy of power estimation decreases when the phase difference between the output voltage v _O and the current i ₁ is large. When the input power is used, the phase difference between the input voltage and the input current is generally small, so that the accuracy of power estimation can be improved. Especially when the input is direct current, there is an advantage that the power estimation is not affected by the power factor.

FIG. 6 is a graph showing the relationship between the total load power P _2T and the effective value I ₁ of the feeder current according to the present invention. The horizontal axis represents the total load power P _2T and the vertical axis represents the vertical axis. The axis represents the feed line current effective value I ₁ . In this graph,
In the range of P _2T ≧ P _TH , the feed line current effective value I ₁ is constant at I _1max , and in the range of P _2T <P _TH , I ₁ is a linear function of P _2T . By adjusting I ₁ according to the relationship shown in the graph of FIG. 6, it is possible to stably supply electric power under any load condition.

In the above description, it has been explained that all of the plurality of pickup side circuits 6 have the same characteristics, and the maximum values of the load powers defined by the circuits are equal and the minimum values are also equal. However, it goes without saying that the present invention can be applied by the same method. Even if a capacitor is added to the power supply line 2 in order to compensate for the inductance of the power supply line 2, the effective components of the input power and the output power of the high-frequency AC power supply 1 do not change substantially. The same effect can be obtained by applying the invention.

Further, when the number of pickup side circuits 6 is one, the method for adjusting the current of the feeder line 2 in the case of P _2T <P _TH can be applied as it is.

[0033]

According to the present invention, in a non-contact power supply device having a plurality of pickup side circuits, a sensor for detecting each load power in each pickup side circuit,
Even without adding a transmission circuit that transmits information from this sensor to the control circuit of the high-frequency AC power supply, the feeder line current can be appropriately controlled in response to changes in load power, making the device complicated. It is possible to eliminate the trouble of maintenance / inspection associated with the above, and to avoid the possibility of reducing the reliability of the device. Of course, the cost increase of the device can be avoided. Further, since the power supply line current can always be maintained at an appropriate value, the conduction loss of the power supply line can be suppressed, the efficiency of the device can be prevented from lowering, and the energy saving effect can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram showing a fifth embodiment of the present invention.

[FIG. 6] Total load power P _2T and effective value I _{1 of} feeder current
A graph showing the relationship with the present invention based on the present invention.

FIG. 7 is a main circuit connection diagram showing a conventional example of a non-contact power supply device.

FIG. 8 is an explanatory circuit diagram for explaining the operation of non-contact power transmission by the non-contact power supply device.

FIG. 9 is an explanatory diagram explaining the principle of estimating load power from the operating condition of the high-frequency AC power supply.

[Explanation of symbols]

 1 high frequency AC power supply 2 power supply line 3 pickup coil 4 voltage regulator 5 load 6 pickup side circuit 7 load power estimation arithmetic circuit 8 current control circuit 10 output current detector 11 power supply output power calculation circuit 12, 17, 22 multiplier 13, 18 Low Pass Filter 15 Input Current Detector 16 Power Supply Input Power Calculation Circuit 20 Feed Line Loss Calculation Circuit 21 Effective Value Calculator 23, 33, 34 Gain 24, 31 Subtractor 32 Limiter 35 Current Regulator

Claims (5)

[Claims] 1. A high-frequency AC power supply, a conductor connected to the high-frequency AC power supply, a plurality of pickup coils magnetically coupled to the conductors, and separately connected to each pickup coil to adjust an output voltage. In a non-contact power supply device including a voltage regulator and a load separately connected to each voltage regulator, the total power consumed by each load is calculated from various amounts detected when the high-frequency AC power supply operates. A contactless power supply device comprising: a load power estimation calculation circuit for estimating; and a current control circuit for controlling a current flowing through the conductor based on the load power estimation calculation value. 2. The contactless power supply device according to claim 1, wherein the load power estimation calculation circuit is generated by a power supply output power calculation circuit that calculates the high frequency AC power supply output power and a current flowing through the conductor. A contactless power supply device comprising a conductor loss calculation circuit for calculating a loss and a subtraction circuit for calculating a difference between the power supply output power calculation value and the conductor loss calculation value. 3. The contactless power supply device according to claim 1, wherein the load power estimation calculation circuit is generated by a power supply input power calculation circuit that calculates the high frequency AC power supply input power and a current flowing through the conductor. A contactless power supply device comprising: a conductor loss calculation circuit for calculating a loss; and a subtraction circuit for calculating a difference between the power supply input power calculation value and the conductor loss calculation value. 4. The contactless power supply device according to claim 1, wherein the current control circuit keeps a current flowing through the conductor constant when the load power estimation calculation value is equal to or more than a predetermined value. A non-contact power supply device, characterized in that the current flowing through the conductor is controlled to be lower than the predetermined value when the load power estimation calculation value is less than the predetermined value. 5. The non-contact power supply device according to claim 1, wherein the current control circuit controls the current flowing through the conductor when the load power estimation calculation value is less than the predetermined value. A contactless power supply device, which is controlled so as to be reduced by a linear function of an estimated power value or a function equivalent thereto.