JP2001060218A - Analyzing device for noncontact electric power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an analyzing device which can transmit the transmission efficiency of a noncontact electric power transmission system, transmitting electric power from a primary to a secondary inductor, with high precision at high practical level while taking the end part effect of the inductors into account. SOLUTION: The analyzing device comprises an input means 1, a computer 10, a display device 21, and an output device 22 and the computer 10 is equipped with a storage part 13, a magnetic circuit arithmetic means 14, an electric circuit arithmetic means 15, and a transmission efficiency arithmetic means 16. The magnetic circuit arithmetic means 14 obtains the inductances of the primary and secondary inductors by an equivalent magnetic circuit method and the electric circuit arithmetic means 15 calculates the current and voltage and efficiency of an electric circuit to take an analysis for designing an inductor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analyzer for analyzing power transfer efficiency of a wireless power transfer system for wirelessly transmitting power from a ground to a mobile load traveling on a road surface.

[0002]

2. Description of the Related Art For an electric vehicle equipped with a battery and running by an electric motor, power is supplied from a primary inductor buried in the road to a secondary inductor mounted on the electric vehicle as a driving energy in a non-contact power supply system. In addition, various traffic systems have been proposed that charge the battery mounted on the electric vehicle and greatly extend the mileage of the electric vehicle after leaving the system. One example is the proposal of a new system based on a paper entitled "Basic Study on Non-Contact Power Transfer Method for Mobile Load" (Journal of the Japan Society of Applied Magnetics, VOL21, No.4-2, 1997, P697-700). Have been.

In the new system according to this paper, 250 ×
A coil group in which a number of 80 mm rectangular vertically-long spiral coils are linearly arranged such that their long sides are adjacent to each other is buried in two rows on the road surface, and this is used as a power transmission side coil, and electricity running on it is run. A power-receiving coil using a spiral coil is provided on the vehicle side, and power is supplied only to the power-transmitting coil immediately below by a signal from the sensor coil on the long side of the power-transmitting coil, and partial excitation is used to supply power to the power-receiving coil. We have proposed a wireless power transfer method.

In such a non-contact power supply type power transmission system, the power transmission efficiency is maximized,
In order to rationally design each component including the secondary inductor and the secondary inductor, it is important to analyze the magnetic circuit formed by the transmitting and receiving coils, and one of the methods is to analyze the magnetic field using the three-dimensional finite element method. There is a law.

In the three-dimensional finite element method, an electric vehicle is placed immediately above a power transmission side coil, and is transmitted there while being stationary. A magnetic circuit including a power reception coil is divided innumerably in a three-dimensional direction, and magnetic fields between the elements are divided. Calculate the change from one end to the other end of each element with a computer for the mathematical expression representing
Analyze the magnetic circuit.

[0006]

By the way, research similar to that of the new system proposed in the above-mentioned non-contact power supply system paper has been published in various papers other than the above, but in any case, the power is not available. In many cases, transmission experiments have been performed and the results have been reported. The actual situation is that sufficient evaluation of the measurement results could not be performed because the experiments were advanced and the analysis method was not established.

[0007] The reasons are that the analysis of the magnetic circuit is insufficient, the dynamic analysis cannot be performed when the vehicle moves, or the loss generated in the circuit cannot be estimated. Although the above-mentioned magnetic field analysis by the three-dimensional finite element method is effective for the analysis of the magnetic circuit, it is actually difficult to create a model that accurately represents the eddy current distribution in the core and at the end. Therefore, the analysis results by the finite element method that the present inventors have attempted do not agree with the experimental results significantly.

The calculation is performed by processing a huge amount of data assuming a certain stationary state. When the vehicle moves and the circuit constants of the system fluctuate with time, a huge amount of data is processed each time. To recalculate
Too much work and cost, and even though analysis by 3D finite element method has been done,
No paper has been published that reports accurate magnetic circuit analysis.

As an attempt to solve various inconveniences of the magnetic circuit analysis method by the three-dimensional finite element method, the title using the equivalent magnetic circuit method is "A study on the Inducti
ve Coupling System ”
The paper on the method of analyzing magnetic circuits, titled “The World Congress on Intelligent Transport Syst.
ems) on November 9-11, 1995 (in Yokohama).

The analysis method using the equivalent magnetic circuit method is as follows.
The electric circuit including the secondary inductor and the secondary inductor is replaced with an equivalent magnetic circuit corresponding thereto, and various parameters of the equivalent magnetic circuit are calculated by giving known magnetic physical characteristic values.

However, in the analysis method using the equivalent magnetic circuit method, when determining the circuit constants of the modeled equivalent electric circuit and the equivalent magnetic circuit, it is most likely that the vehicle completely overlaps the primary inductor. It is proposed to calculate a constant value that can be considered in a two-dimensional cross section at a representative position. At this time, the magnetic flux at the end of each of the primary inductor and the secondary inductor divided into respective predetermined lengths is proposed. No consideration is given to leakage. For this reason, the value of the power transfer efficiency calculated based on the equivalent magnetic circuit method still largely deviates from the experimental result, and the analysis method has not reached a practical accuracy.

However, recent studies by the present inventors have shown that the effect of magnetic flux leakage at the ends of each of the primary and secondary inductors is extremely large. It was clarified that the power transfer efficiency calculated with the circuit method matched the measured value with extremely high accuracy. In addition, since the accuracy of the analysis by the conventional equivalent magnetic circuit method is not at a practical level, a study is made on a dynamic power transfer efficiency change when a ratio of a vehicle overlapping each primary inductor is changed by a movement of the vehicle. I couldn't do that either.

The present invention has been made in consideration of various analytical problems in the conventional wireless power transmission system described above.
An object of the present invention is to provide an analysis device for a non-contact power system that enables a system analysis at a higher practical level by taking into account the effect of the inductor end effect in the analysis of power transfer efficiency.

[0014]

SUMMARY OF THE INVENTION The present invention, as a means for solving the above-mentioned problem, analyzes a system for transmitting power from a primary inductor on the ground side to a secondary inductor provided on a mobile load in a non-contact manner. , Inductor conductor, iron core,
Input setting means for inputting input data relating to various parameters necessary for the analysis including the coil, load, and power supply frequency, and setting an electric circuit and a magnetic circuit modeled from these input data; and Magnetic circuit operation means for calculating inductance using a predetermined operation expression based on an equivalent magnetic circuit method, and a power supply corresponding to desired secondary power using an electric circuit constant and input data obtained by further operation from the operation result Electric circuit operation means for obtaining a voltage, a current flowing through each part of the electric circuit, a magnetic flux density of an inductor, and a loss including an iron loss, and storage means for storing various data including the input data, the operation value, and the output data of the operation result And setting the constant of the electric circuit set by the circuit setting means so as to include the leakage flux at the end of the inductor. And a non-contact power system analysis device configured to calculate the voltage, current, loss, and efficiency of both inductors to calculate the voltage, current, loss, and efficiency of the inductors, and to calculate the electric circuit in consideration of the leakage at the end of the inductor. It was done.

[0015] The analysis apparatus having such a configuration analyzes various design numerical values such as transmission efficiency when power is transmitted between the primary and secondary inductors of the non-contact power system by electromagnetic induction. Numerical values required for design, such as the number of turns of the conductor, core, coil, and load power, as design data, are stored in advance in a storage unit by an input unit, and a magnetic circuit between the primary and secondary inductors is set using these. , The magnetic resistance value is calculated in advance.

Next, based on the equivalent magnetic circuit method established for the magnetic circuit, the magnetic circuit operation means uses the primary circuit,
The secondary side self-inductances L ₁ and L ₂ and the mutual inductance M are obtained, and are converted into the primary side and the secondary side leakage inductance and the mutual susceptance by a necessary relational expression. As a result, the circuit constants of the electric circuit constituting the primary and secondary inductors can be obtained excluding the iron loss g.

Using the circuit constants obtained in this way, a power supply voltage capable of supplying a necessary current voltage to the load side is obtained by the electric circuit computing means based on the equation for the electric circuit network, and the primary and secondary power supply voltages are used. Find the current value of each part of the inductor. At this time, the calculation is performed assuming that iron loss g = 0.

When the current value of each part of the inductor is obtained, the magnetic flux density of each part is calculated, and the loss in the core and the end loss are calculated. The iron loss value is given by the relationship between the magnetic flux density and the iron loss value, and the end loss is given by the end loss calculation formula. Therefore, the value of the iron loss value and the value of the end portion loss obtained above were added to the value of g, and the power supply voltage was recalculated.
It is checked whether the load current value at that time is within a predetermined error range from the set current value. If it is within the error range, the power transmission efficiency at that time and the current and voltage values of each unit are the design values to be obtained.

If the error is out of the error range, the above calculation is repeated until the condition within the error range is obtained by changing the design constant to obtain the optimum condition. The above description is based on the assumption that the overlap between the primary and secondary inductors is 100%, but the overlap ratio dynamically changes because the secondary inductor of the vehicle moves. The change in the transmission efficiency can be calculated by the transmission efficiency calculation means in accordance with such a dynamic change of the overlap.

It has been found that in the dynamic change of the overlap, the inductance value and the iron loss change linearly. Thereby, the inductance value and the iron loss value are changed in accordance with the overlap ratio, and at the same time, the time change is assumed from the moving state of the vehicle corresponding to the overlap ratio, and the primary equation is applied by applying the difference equation to the electric network. The change of the current and voltage of each part of the secondary inductor is obtained, and the change of the power transfer rate at each time is obtained.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram of an analyzer of the wireless power transmission system according to the embodiment. In the actual example, the computer 10 is a commercially available personal computer, the input means 1 is a keyboard and a mouse, the display device 21 is a CRT cathode-ray tube, and the output device 2
Printers 2 are used respectively. An input signal from the input means 1 is input set by a calculation unit (CPU) 12 via an input / output control unit 11, and a storage unit 13
Each data is stored.

The storage unit 13 includes a first storage unit 13a and a second storage unit 13a.
The first storage means 13a stores not only input data but also various data such as output data and calculated intermediate data in the form of an input / output data file. Further, the second storage means 13b stores processing programs necessary for arithmetic processing, such as various arithmetic expressions described later in the description of operation, and the like. The operation unit 12 includes a central operation unit (C
Magnetic circuit arithmetic means 1 for performing arithmetic processing centering on the PU)
4, electric circuit operation means 15 and transmission efficiency operation means 16 are included.

Each of the arithmetic means 14 to 16 has a function part for performing necessary arithmetic processing by the processing program of the second storage means 13b using the input data stored in the first storage means 13a. Although it is displayed,
These are actually provided integrally. The processing function of each arithmetic unit will be described together in the description of the operation.

The operation of the analyzer of the embodiment having the above configuration is as follows. This analyzer is used as a non-contact power transmission system to numerically analyze the design data of the electric circuit and magnetic circuit of a new transportation system that transmits power from the primary inductor on the ground side to the secondary inductor provided in the electric vehicle. . Before describing the operation, a non-contact power transmission system, which is a premise, will be briefly described. FIG. 3 shows an example of a target wireless power transmission system.

(A), (b) As shown in the drawings, primary inductors ID (ID _n , ID
_{n + 1} ,...) are separated by a fixed length (for example, about 10 m), and the secondary inductor I
D 'is attached, and although not shown, a sensor system is provided between the vehicle and the ground side, and when it is detected that the vehicle overlaps with the primary inductor ID in the portion where the vehicle overlaps, only the primary inductor ID is detected. A partial energization method for energization is adopted (this is to reduce waste of power consumption).

Assuming the power transmission system as described above,
From the primary inductor ID to the secondary inductor ID '.
Electric and magnetic characteristics of primary and secondary inductors when transmitting force
Optimal circuit constants, and power based on the conditions
The transmission efficiency is calculated and obtained as follows. Hereinafter, FIG.
This will be described with reference to a flowchart. First, step S ₁
Model the primary and secondary inductors by the input means 1
Input into the first storage means 13a
And store it. This input parameter value is as follows
It is.・ Coil resistance calculation: Conductor cross section, conductor length, conductor resistance
Ratio ・ Calculation of magnetic circuit inductance …… Core shape, core gear
Tap length, number of coil turns, iron core permeability ・ Electrical circuit calculation …… Load power W, load voltage V, power supply frequency
Number f The parameter value of the above conductor is the coil forming the inductor.
The core parameter value is the inductor core value.
It represents the shape of the iron core around which the coil is wound.
The power required for the vehicle to travel
The power supply frequency is the voltage supplied to the primary inductor.
A state where the power transmission efficiency is maximized by giving various force frequencies
Is calculated.

When the various parameter values are input, the electric circuit shown in FIG. 4 and the magnetic circuit shown in FIG. 5B are set in steps S ₂ and S ₃ by using the data.
Of the circuit constants, R ₁ , R ₂ , R _L of the electric circuit and various R values of the magnetic circuit are immediately calculated. In this case, the symbols of the electric circuit in FIG. 4 are as follows.

V: Power supply voltage (V) R ₁ : Primary winding resistance (Ω) R ₂ : Secondary winding resistance (Ω) L ₁ : Primary leakage inductance (H) L ₂ : Secondary Side leakage inductance (H) g: Excitation conductance (Ω) b: Excitation susceptance (H) R _L : Secondary load resistance (Ω) The above winding resistances R ₁ and R ₂ are determined by the type and length of the conductor used. This is a known amount that is determined, and is calculated from the input data described above. In this calculation, the conductor cross-sectional area S, the conductor length l, and the conductor resistivity ρ are read from the first storage means 13a, and a resistance calculation program of R = ρ · l / S is read from the second storage means 13b. Circuit setting means (including CPU)
Is performed to calculate the conductor resistance R.
This value of R is stored in the first storage unit 13a.

[0029] R by setting the load voltage V _L and the collector power W _L necessary for the load on the secondary side for R _{L L} = V
It is determined by _L ² / W _L (Ω). In this operation, from the first storage unit 13a reads the current collecting power W _L and the load voltage V _L, reads the load resistance computing program ^{_{R L = V L 2 / W}} L from the second storage unit 13b, the electric circuit set The load resistance R _L is calculated by processing by this means.
The value of _L is stored in the first storage unit 13a.

L ₁ , L ₂ , and b are obtained by the equivalent magnetic circuit method, which will be described later. The actual circuit is analyzed as a circuit in which the power factor improving capacitances C ₁ (F) and C ₂ (F) of the power supply are inserted into the primary and secondary circuits, respectively. Since this is not an essential problem, the following description will be made as a circuit in which C ₁ and C ₂ are omitted.

Further, in the cross section corresponding to FIG.
FIG. 5A shows the flow of the magnetic flux generated between the secondary inductors and the leakage magnetic flux generated at the end of the inductor. Assuming each magnetic path, a magnetic resistance is set for each magnetic path.
Assuming that a magnetic circuit including these magnetic resistances is similar to an electric circuit, an equivalent magnetic circuit shown in FIG. 5B is obtained. The reluctance is determined in the core (Riah, Ribh, Ridg, Ri).
fg), air gap and edge (Rad, Rbe, R
cf) and leakage flux (Rab, Rbc, Rde, Re)
f) and is calculated by the following equation. R = l / μs (AT / Wb) 1: magnetic path length (m) μ: magnetic permeability (Wb / AT · m) S: cross-sectional area (m ² ) In the above calculation of the magnetic resistance, the first storage means 13a More 1
Next, the shape data and magnetic permeability of the secondary and secondary inductors are read, and the magnetic resistance calculation program of the above equation (R = L / μs) is read from the second storage means 13b, and not shown for each magnetic path shown in FIG. The magnetic resistance R is calculated by the magnetic circuit setting means, and the value of R for each magnetic path is stored in 13a.

Note that the above equation holds for a magnetic path whose cross section S and magnetic path length 1 are magnetic permeability μ. From this, the magnetic resistance R is determined by the geometrical shape of the magnetic circuit and the magnetic permeability μ. It can be seen that the larger the cross-sectional area through which the magnetic flux passes and the shorter the distance, the smaller. In general, the magnetic permeability μ of the iron core is 100 to 1000 times that of air, and the magnetic resistance of the air gap is much larger than that of the air inside the iron core. The air gap and the magnetic resistance at the end are represented by the following equations according to FIG.

Rad = Rad ₁ · Rad ₂ / (Rad ₁ + Rad ₂ ) Rbe = Rbe ₁ · Rbe ₂ / (Rbe ₁ + Rbe ₂ ) Rcf = Rcf ₁ · Rcf ₂ / (Rcf ₁ + Rcf ₂ ) This is a magnetic circuit network. This is an operation for simplifying.

From the above, when the flow of each magnetic flux is determined as shown in FIG. 5A, the magnetic resistance R of each part is calculated. An input setting means is constituted by the input means 1 and the electric circuit setting means and the magnetic circuit setting means.

[0035] When the setting of the magnetic circuit is completed in the above step S ₄ in the magnetic circuit calculating unit 14 by the the magnetic resistance R of each part of the magnetic circuit on the basis of the magnetic circuit in Ohm's law shown in FIG. 5 (b) magnetic flux φ Is calculated by the following equation.

NI = R · φ The magnetomotive force NI is represented by the product of the number of turns N of the coil and the current I, and corresponds to the electromotive force V of the electric circuit. The magnetic flux φ is the current I, and the magnetic resistance R is the electric resistance r. Each corresponds.

In the above calculation, the inductance described below is obtained first, and the current value I is obtained by analyzing the electric circuit.
Is obtained by obtaining the currents I ₁ , I ₂ , and I ₃ of the circuit components, and the above arithmetic expression will be described first for convenience of explanation.

When the magnetic flux of the magnetic circuit is obtained as described above, the primary and secondary inductances L ₁ and L ₂ and the mutual inductance M are calculated by the equivalent magnetic circuit method as follows. First, regarding the inductance, the self-inductance of one circuit is the number of magnetic fluxes linked to the circuit when a unit current flows in the circuit, and the mutual inductance between the two circuits is the unit when the unit current flows in one circuit. Because it is the number of magnetic flux linking with the other circuit, the primary side excitation,
The self-inductances L ₁ and L ₂ and the mutual inductances M ₁ and M ₂ in the respective circuits of the secondary excitation are expressed by the following equations.

L ₁ = N ₁ φ _a1 / I ₁ (primary side excitation) M ₁ = N ₂ φ ₁ / I ₁ (primary side excitation) L ₂ = N ₂ φ _a2 / I ₂ (secondary side excitation) ) M ₂ = N ₁ φ ₂ / I ₂ (secondary excitation) In the above equation, φ _a1 : the number of magnetic fluxes linked with the primary excitation circuit by primary excitation φ ₁ : secondary by secondary excitation The number of magnetic flux linking with the secondary excitation circuit φ _a2 : The number of magnetic flux linking with the secondary excitation circuit by secondary excitation φ ₂ : The number of magnetic flux linking with the primary excitation circuit by secondary excitation From the obtained M ₁ and M ₂ , the mutual inductance M of the circuit is represented by the following equation.

M = √M ₁ · M ₂ φ _a1 and φ ₁ in the above equation are as shown in FIG.
These are the magnetic fluxes of the primary side coil and the secondary side coil in the case of the primary excitation, respectively. Therefore, the values of the self-inductance L ₁ and the mutual inductance M _{1 of the} primary excitation are represented by the above-described magnetic fluxes φ _a1 , φ
_{When 1} is obtained, it can be specifically determined.

[0041] When finding the self-inductance L _1, in the above two different equations phi, although the seek self-inductance L ₁ by the value of I, such that the self-inductance L ₁ is described below by modifying these equations In addition, it can be obtained irrespective of φ and I (there is no change in the magnetic permeability due to the change in the current value I). That is, the actual example is assumed as shown in FIG. 6, and the magnetic resistance R to the magnetic flux in the left and right iron cores is determined from the symmetry of the cross section of the coil.
It can be assumed as shown in FIG. 6A that i is equal and the leakage magnetic flux Ra is also equal on the left and right. However, (a) shows a state where the vehicle overlaps the corresponding primary inductor (during coupling), and (b) shows a state where it does not overlap at all (during non-coupling).

When the above assumption is made and the magnetic resistance of the iron core is considered and ignored, the primary side self inductance L ₁ is obtained by the following equation. Consideration of iron core resistance L ₁ = 2N ² ｛Ra ² + (A + r ′) (Ri + Ra)｝ / ｛(A + r) (Ri + Ra) ² … ... At the time of coupling L ₁ = 2N ² / (R'a + Ri) ... uncoupled during core resistance ignored ^{_{L 1 = 2N 2 (Ra +}} r + 2r ') / (R + 2r') Ra ............ coupling when ^{_{L 1 = 2N 2 / Ra '}} ............ when uncoupled However, r' is r and r _a1 are constants. In the actual calculation, an equation considering the core resistance was used to improve the calculation accuracy.

[0043] When obtaining the self-inductance L ₁ by the above equation, reads the magnetic resistance R of each magnetic path from the first storage unit 13a, a magnetic read the inductance calculation program according to the above equation when the coupling from the second storage means 13b It is processed by the circuit operation means 14, and L at the time of coupling is
Calculate ₁ . The value of L ₁ for each path stored in the first storage means. Although not described in detail, L ₂ and M are also calculated by similar operations.

Note that the self-inductances L ₁ and L ₂ and the mutual inductance M determined by the above equivalent magnetic circuit
And the primary and secondary leakage inductances L ′ ₁ and L ′ ₂ and the excitation susceptance b, the following relationship is established.

L ′ ₁ = L ₁ −aM (H) L ′ ₂ = a ² L ₂ −aM (H) b = aM (H) a = N ₁ / N ₂ (turn ratio) N ₁ : primary The number of turns of the side coil N ₂ : the number of turns of the secondary coil However, L ′ ₁ and L ′ ₂ are L ₁ and L ₂ in the above case, and the same reference numerals are used for convenience, but L ′ ₁ and L ′
₂ shall be replaced with L ₁ and L ₂ as necessary for the sake of explanation.

When the leakage inductance L ′ is obtained from the self inductance L by the above relational expression, the self inductance L ₁ obtained by the above calculation from the first storage means 13a,
L ₂ , the mutual inductance M and the number of turns N ₁ , N ₂ are read out, and a program for calculating the turns ratio G = N ₁ / N ₂ is read from the second storage means 13 b to obtain the turns ratio G, and the value is used as the first turns. It is stored in the storage unit 13a.

Then, the calculation program for the leakage inductance stored in the second storage means 13b is read out, the primary and secondary leakage inductances L ' ₁ and L' ₂ are calculated, and the values are stored in the first storage means 13a. To be stored. Similarly, the processing of the excitation susceptance b is performed.

When the leakage inductance values L ₁ and L ₂ on the primary side and the secondary side are obtained as described above, the values of the respective circuit constants of the electric circuit of FIG. 4 are obtained except for the iron loss parameter g. Become. However, in this case, as can be seen from the above description, the inductance values L ₁ and L ₂ are values determined by the geometrical shape and the magnetic permeability of the coil, and are determined independently of the current value.

The inductance L ₁ by analysis of the magnetic circuit as described above, when L ₂ is obtained, electricity by applying these values for the network following equation for the electric circuit of FIG. 4 in step S ₆ The circuit can be analyzed.

V = (R ₁ + g + jωL ₁ ) I ₁ −gI ₂ O = (g + jωb) I ₂ −gI ₁ O = (jωb + jωL ₂ + R ₂ + _RL ) I ₃ −jωbI
_{2 When the} above equation is displayed in a matrix,

[0051]

[0052] Therefore, first, in step S _5, set the iron loss parameter g = 0 among the parameters in an electric circuit. Next, the impedance matrix using the above circuit constants calculated at S ₆₁ in step S _6, and calculates the supply voltage V to obtain a desired secondary power. 2
Since the load power and voltage on the secondary side are given as basic design values of the traveling vehicle, they are given by input data. Therefore,
It reads the input data from the first storage unit 13a, to obtain a load current I ₃ from that value.

The current distributions I ₁ , I ₂ ,
The magnetic flux distribution generated by I _{3 is} calculated by the equivalent magnetic circuit shown in FIG. The magnetic flux density B of each part is calculated from the magnetic flux distribution and shape of each part by the above-mentioned relational expression of φ and I.

When the magnetic flux density B (W _b / m ² ) of each part is calculated, the loss in the iron core and the end loss are calculated in step S _{63 based on} the magnetic flux density. In this case, the loss in the iron core is stored in advance in the storage means as a characteristic value of the iron core material in the graph shown in FIG. 7, and when the magnetic flux density is obtained, the corresponding iron loss value is obtained from the graph of FIG. Is calculated. In FIG. 7, when the calculated value P of the magnetic flux density is substituted, the loss value Q per unit weight is obtained, the weight is calculated from the shape and the density, and the iron loss value in the iron core is obtained from the loss value Q. .

On the other hand, the end loss value is obtained by the following equation. In the present invention, the edge loss value has an important meaning in obtaining an analysis accuracy as a sufficient value that does not hinder practical use. The significance will be described later.

[0056] ^{_{W e = δ e t 2 f}} 2 Bm 2 (W / kg) δ e = 13.0 × 10 -4 It should be noted, Bm in the formula are calculated by a magnetic flux and an end portion shaped to penetrate the end The magnetic flux density, t is the thickness of the steel sheet, and f is the power supply frequency. Further, δ _e is a loss coefficient of eddy current loss, and a typical value of a grain oriented silicon steel sheet is used. The above equation is a general equation for calculating an eddy current loss of a transformer or the like, and is an equation for calculating an eddy current loss generated for a magnetic flux density generated at a coil end.

[0057]

This error is within a certain allowable range, for example, 5%
Within the error range of the above, the design values of the respective parts can supply the electric power required for the vehicle of the load. However, if the error is larger than the allowable range, the process returns to the original step S ₇ (back to S ₆₁₎ is performed again similar calculation, the load current I
_The balance calculation is repeated so as to obtain a design value in which the error from ₃ is reduced. If the error is less than the allowable range, the inductor design specification in that state is set as desired and the calculation is terminated.

In the case where the electric circuit is operated by the electric circuit operation means 15 according to the above relational expressions, the first storage means 1
Collector power W _L from 3a, reads out the load voltage V _L, the second
An operation program of load electricity I ₃ = W _L / V _L is read from the storage unit 13b to calculate I ₃ , and this is stored in the first storage unit 13a. Next, the electric circuit parameters L ₁ , L ₂ , b, R ₁ , R ₂ , and g are read from the first storage unit 13a.

Then, the read value and the initial value
V₀Load current I at_Three’And calculate this as the first memory
Stored in stage 13a. Again from the first storage means 13a
I_Three, I _Three′, And load from the second storage unit 13b.
The current comparison program is read and I_ThreeAnd I_Three’
And, depending on the error, V₀And the value is stored in the first storage unit 1
3a. The above operation is repeated, and the error is
(For example, 5%), the power supply voltage V,
It is stored in the first storage means 13a.

The current supply and the magnetic resistance are read out again from the first storage means 13a, the equivalent magnetic circuit calculation program is read out from the second storage means 13b, the magnetic flux φ at each part of the inductor is calculated, and the value is stored in the first storage means. 13a. Thereafter, the shape parameter and the magnetic flux φ are read from the first storage means 13a, the magnetic flux density calculation program is read from the second storage means 13b, the magnetic flux density B of each part is calculated, and this is stored in the first storage means 13a.

To determine the iron loss, the first storage means 1
The magnetic flux density B and the value of the shape parameter are read from 3a,
A calculation program (or database) for the magnetic flux density between iron cores and iron loss is read from the second storage means 13b, the iron loss in the iron core is calculated, and this is stored in the first storage means 13a. Further, the magnetic flux density B and the shape parameter are read from the first storage means 13a, the end loss calculation program is read from the second storage means 13B, and the end loss is calculated.
It is stored in the storage means 13a.

Each part voltage obtained by the above analysis method,
Values such as current, loss, and efficiency are output and displayed on the display device 21 or printed by the output device 22.

The significance of the edge effect described above in the above analysis is as follows. A non-contact power supply system to be analyzed by this analysis device is a primary transformer of the order of -2.
It is a configuration in which the next stage is separated, and is different from a general transformer (transformer) only in having an air gap between the first and second stages for the purpose.

Normally, in a transformer, in order to reduce iron loss (mainly eddy current loss) caused by a change in magnetic flux φ passing through the iron core, a thin metal plate (generally, a silicon steel plate is highly transparent in the direction of magnetic flux travel) is used. Often used because of its magnetic susceptibility and high resistance)
Is used. In this transformer, when the direction of the silicon steel plate and the direction of the magnetic flux φ are set as shown in FIG. 8A, the relationship between the magnetic flux density and the iron loss can be obtained from the graph of FIG. This is because, in order to improve the efficiency of the transformer, a configuration is adopted in which magnetic flux entering from a direction other than that shown in FIG.

However, in the above-mentioned non-contact power supply system, since an air gap exists between the primary and secondary sides due to the structure, the magnetic flux leaking from the iron core portion to the external space is inevitably increased. This is a characteristic of this system.
In this system, the direction of the magnetic flux in the core
(B) is φ ₀ , and a thin steel plate is inserted in this direction. Due to the presence of the air gap, magnetic fluxes mainly passing through the outer space of the iron core of φ ₁ and φ ₂ are generated.

Where φ_TwoIs related to the thickness direction of the steel sheet
φ₀(The magnetic coupling is weak due to leakage.
The iron loss calculation)
Is φ ₀Similarly, the above-described relationship of FIG. 7 is established. However, the book
Magnetic flux φ generated at the end face of the system₁Is shown in FIG.
As shown in FIG.
The relationship does not hold, and is calculated using the formula for finding the end loss described above.
You.

Therefore, in this embodiment, as a result of conducting an experimental study, it was found that, in addition to the iron loss in the iron core shown in FIG. . Therefore, in the design of the contactless power supply system, it is very important to calculate the total loss including the effect at the end face. Therefore, in the above analysis method and that correctly evaluate the effect by calculating the load current I _3, including the end losses in the calculation of the electrical circuit, thereby the calculation result of the power transmission efficiency is high and the experimental results They were matched with precision.

[0069] or when the vehicle is traveling has been a description of the analysis method of the system in static state of being located at a predetermined overlap ratio with respect to the primary inductor, then the running vehicle at step S ₈ has moved 1 The dynamic efficiency change calculation is performed to determine how the power transfer efficiency changes when the overlap ratio with the next inductor changes.

When the upper inductor moves dynamically,
The positional relationship between the primary side inductor and the vehicle side inductor relatively changes, and the mutual magnetic coupling changes. For this reason,
The respective self-inductance, mutual inductance and iron loss change. When the coupling ratio is determined as shown in FIG. 9 (a), a state in which both are completely overlapped in the longitudinal direction is 100.
%, And the state of no overlap at all is 0%, and the intermediate value is linearly complemented. This is based on the conclusions obtained from the experimental results and the calculation results in FIG.

An experimental result was obtained that the primary side inductance value at the overlapping ratio of 25% and 50% changes in first order proportion to the overlapping ratio. The calculation results showed the same change. Similarly, with respect to iron loss, a result was obtained in which both the calculation result and the experimental result changed in a first-order proportion to the overlapping ratio (see the following table).

[0072]

[Table 1]

Therefore, for each parameter in the dynamic case from such a result, the inductance and iron loss at that moment are calculated from the relative positional relationship between the two at a certain moment, and these values are calculated as follows. By performing the sequential calculation by substituting the difference equation into the difference equation, a dynamic transmission efficiency can be obtained.

When calculating the dynamic change in the power transmission efficiency, the inductance and the iron loss at the time of 0% and 100% coupling are read out from the first storage means 13a, and the initial coupling state is set from this. Second storage unit 13b
Each constant calculation program is read at a more arbitrary coupling ratio. From the above, each constant at a certain time (positional relationship) is calculated and stored in the first storage unit 13a.

The constants and other circuit constants are read out from the first storage means 13a, the difference equation program is read out from the second storage means 13b, and the instantaneous value of the current flowing through each part at a certain time is calculated. Storage means 13
Stored in a. The above operation is repeatedly performed while being changed by a certain minute time from the initial state, and the operation ends when the set end time comes.

As described above, the analyzing apparatus of this embodiment stores the input signals from the input means in the storage means, and uses these values in the magnetic circuit operation means based on the equivalent magnetic circuit method. The inductance value of the inductor is calculated, and the power supply voltage and the current flowing through each part are obtained from the equation for the electric circuit network by the electric circuit calculating means using the circuit constant value obtained by the calculation. By obtaining each of the above values to obtain an accurate condition that matches the actual power transfer state, the power transfer efficiency and each part can be obtained with sufficient practical accuracy to meet the desired load condition. There is a great advantage that an analyzer capable of obtaining current and voltage can be realized.

In the above calculation, if the current value obtained by the calculation does not approximate the desired set load current value within a predetermined error range, the above-described calculation can be repeated by the energizing current converging means to converge on the predetermined error range. Also, the voltage, current, power transmission efficiency,
The above calculation can be performed according to the dynamic change by applying the difference equation based on the inductance and the iron loss value changed in accordance with the overlapping ratio of each inductor in the process of calculating the circuit loss and sequentially calculating by the transmission efficiency calculating means. Thus, unlike the conventional three-dimensional finite element method, a remarkable effect that analysis of design conditions corresponding to dynamic changes can be easily realized is obtained.

[0078]

FIG. 10 is a main sectional view of a reduced model used in an experiment of a non-contact transmission system.

[0079]

[Table 2]

According to the above-described model, calculation of the voltage, current, power, iron loss, inductance, efficiency, etc. of each part in the power transmission from the primary side to the secondary side by the analysis method in the above embodiment, with the overlapping ratio being 100%. The results and the experimental results are shown in the following table and FIG.

[0081]

[Table 3]

[0082]

[Table 4]

FIG. 11 (b) shows the instantaneous transmission efficiency calculation results and measured values at each time when the above-described method for calculating the dynamic transmission efficiency is applied to the 30% reduced model at the laboratory level. The following shows a comparison. At N = 0, the transmission efficiency increases as soon as the vehicle-side inductor starts to enter the ground-side inductor. At about N = 120, the two completely coincide with each other in the longitudinal direction, and the transmission efficiency becomes maximum. Then, the efficiency starts to decrease again.
In the vicinity of 200, the vehicle-side inductor is completely separated from the ground-side inductor, and power transmission becomes zero. From the above, the validity of the above calculation method was confirmed.

[0084]

The analysis apparatus of the present invention calculates the electric network by including the end loss of the primary and secondary inductors in the value of the iron loss, and performs an accurate analysis corresponding to the actual power transmission state. Since it can be executed, it is not only to confirm the state that the power can be transmitted simply by creating a model as in the past,
The advantage is obtained that the power transfer efficiency between the primary and secondary inductors, the current of each part, and the voltage value can be obtained with more realistic and sufficient accuracy.

[Brief description of the drawings]

FIG. 1 is an overall schematic block diagram of an analyzer according to an embodiment.

FIG. 2 is a schematic diagram of an analysis flowchart according to the above.

FIG. 3 is an explanatory diagram of a non-contact power transmission system.

FIG. 4 is an electric circuit diagram to be set

FIG. 5 is a magnetic circuit diagram to be set.

FIG. 6 is a magnetic circuit diagram in actual calculation.

FIG. 7 is a graph showing a relationship between magnetic flux density and iron loss.

FIG. 8 is an explanatory diagram of an action of a transformer and an inductor.

FIG. 9 is an explanatory diagram of an overlapping ratio and a graph of a change in a primary side inductance value.

FIG. 10 is a main sectional view of a 30% reduced model.

FIG. 11 is a graph of a change in transmission efficiency and a graph of a change in dynamic transmission efficiency.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input means 10 Computer 11 Input means control part 12 Operation part 13 Storage part 14 Magnetic circuit operation means 15 Electric circuit operation means 16 Transmission efficiency operation means 21 Display device 22 Output device

Continuing on the front page (72) Inventor Makoto Kusuma 4-1 Egasakicho, Tsurumi-ku, Yokohama-shi Tokyo Electric Power Research Institute, Inc. (72) Yasuyuki Sugii 4-1 Egasakicho, Tsurumi-ku, Yokohama Tokyo Electric Power Stock F-term in the Electric Power Research Laboratory of Japan (reference) 5B046 AA04 AA07 JA07

Claims (3)

[Claims] In order to analyze a system for transmitting power from a primary inductor on the ground side to a secondary inductor provided on a mobile load in a non-contact manner, a system including an inductor conductor, an iron core, a coil, a load, and a power supply frequency. Input setting means for inputting input data relating to various parameters required for analysis and setting an electric circuit and a magnetic circuit modeled from the input data, and a predetermined operation based on an equivalent magnetic circuit method for the set magnetic circuit Magnetic circuit calculating means for calculating the inductance using the formula, a power supply voltage corresponding to a desired secondary power using an electric circuit constant and input data obtained by further calculation from the above calculation result, a current flowing through each part of the electric circuit, An electric circuit operation means for calculating the magnetic flux density of the inductor and loss including iron loss, and the input data, the operation value, and the output data of the operation result Storage means for storing various kinds of data, including the constant of the electric circuit set by the circuit setting means so as to include the leakage magnetic flux at the end of the inductor. A non-contact power system analysis apparatus configured to calculate the voltage, current, loss, and efficiency of both inductors and to analyze the system by taking into account the leakage of the power. 2. The calculation by the magnetic circuit calculation means and the electric circuit calculation means until the current value of the secondary power obtained by the electric circuit calculation means for a desired current of the secondary power falls within a predetermined allowable range. The analysis device for a contactless power system according to claim 1, further comprising a conduction current convergence unit that executes a repetitive operation. 3. A process of calculating voltages, currents, power transmission efficiencies, and circuit losses of respective parts on a power supply side and a load side based on a load current value determined by the energizing current convergence means. Considering the rate of change that changes according to the overlap ratio with the ground-side inductor, the values calculated from the relative positional relationship in the longitudinal direction of the two are sequentially calculated using a predetermined difference equation to calculate the dynamic change in power transfer efficiency. 3. The analysis device for a wireless power transmission system according to claim 2, further comprising a transmission efficiency calculating unit for calculating the transmission efficiency.