DE102018218581A1 - Method for determining a coupling inductance and / or a variable proportional to the coupling inductance, control unit - Google Patents

Abstract

The invention relates to a method for determining a coupling inductance and / or a variable proportional to the coupling inductance, in particular a coupling factor, an energy transmission device (1), the energy transmission device (1) comprising a first coil (2) and one of the first coil (2). has electrically separated second coil (3). It is provided that an electrical alternating voltage or an electrical alternating current is applied to the first coil (2), that at least one first voltage value of one of the coils (2, 3), at least one first current value of the first coil (2) and at least one second Current value of the second coil (3) are determined, and that depending on an electrical resistance of one of the coils (2, 3), a self-inductance of one of the coils (2, 3), the first voltage value, the first current value and the second current value Coupling inductance and / or the size can be determined.

Description

The invention relates to a method for determining a coupling inductance and / or a variable proportional to the coupling inductance, in particular a coupling factor, of an energy transmission device, the energy transmission device having a first coil and a second coil electrically separated from the first coil.

The invention also relates to a control device for carrying out the method mentioned at the beginning.

State of the art

Energy transmission devices of the type mentioned are known. For example, inductive charging stations have a first coil. If an electrical alternating current or an electrical alternating voltage is applied to the first coil, a coil current is generated in the first coil and a magnetic field is generated by the coil current or by the first coil. If a second coil, which is electrically separated from the first coil, is now suitably arranged in the magnetic field, an electrical voltage is induced in the second coil by the magnetic field, with the induced voltage, for example, operating a consumer electrically connected to the second coil or one electrically connected to the second coil connected energy storage can be charged. With a suitable arrangement of the second coil, the first coil and the second coil thus form an energy transmission device.

Disclosure of the invention

The method according to the invention with the features of claim 1 has the advantage that a coupling inductance of the energy transmission device is determined simply and reliably. Alternatively or additionally, a variable proportional to the coupling inductance, for example a coupling factor, is determined by the method according to the invention. Knowing the coupling inductance or the size offers advantages from a control point of view. For example, the coupling inductance or the size can be used to determine whether an energy transfer between the first coil and the second coil is possible or takes place, or with what efficiency the energy transfer is possible or takes place. According to the invention, it is provided that an electrical alternating voltage or an electrical alternating current is applied to the first coil, that at least a first voltage value of one of the coils, at least a first current value of the first coil and at least a second current value of the second coil are determined, and that in Depending on a resistance of one of the coils, a self-inductance of one of the coils, the first voltage value, the first current value and the second current value, the coupling inductance and / or the size are determined. The method according to the invention thus determines at least the quantities which are required to determine the coupling inductance. In particular, the first voltage value, the first current value and / or the second current value are recorded. Accordingly, measuring devices are used which are designed to directly record the above-mentioned values. As an alternative to this, a measuring device is used to determine at least one of the values, which does not directly record the value, i.e. the first voltage value, the first current value or the second current value, but rather a value, depending on which the first voltage value, the first current value or the second current value is calculated or determined. A voltage value of the first coil is preferably determined as the first voltage value. Alternatively, a voltage value of the second coil is determined as the first voltage value. The coupling inductance and / or the size are preferably determined as a function of the resistance and the self-inductance of those of the coils, the voltage value of which is determined and taken into account when determining the coupling inductance and / or size.

According to a preferred embodiment, it is provided that a plurality of first voltage values, a plurality of first current values and / or a plurality of second current values are determined and taken into account when determining the coupling inductance and / or the variable. This has the advantage that the accuracy when determining the coupling factor and / or the size is increased. In this case, a first of the first voltage values, first current values and / or second current values is preferably determined or recorded at a different point in time than a second of the first voltage values, first current values and / or second current values.

A first voltage curve is preferably determined as the first voltage value, a first current curve as the first current value and / or a second current curve as the second current value. This further increases the accuracy of the method.

According to a preferred embodiment, provision is made for a first voltage amplitude to be determined as the first voltage value, a first current amplitude as the first current value and / or a second current amplitude as the second current value. This has the advantage that the method can be carried out inexpensively. In particular, according to this embodiment, measuring devices for determining or detecting the first voltage value and / or the current values are used, which are less expensive than such measuring devices by means of which a voltage curve or current curve could be determined or recorded.

A first square voltage means is preferably determined as the first voltage value, a first square current means as the first current value and / or a second square current means as the second current value. This also has the advantage that the method can be carried out inexpensively due to the simple design of the measuring devices.

According to a preferred embodiment, it is provided that a first derivative and / or a second derivative are determined as a function of the first current value and that the coupling inductance and / or as a function of the first derivative and / or the second derivative or the size can be determined. This has the advantage that the coupling inductance and / or the size can be calculated particularly easily, in particular according to equation (0.1) below.

The coupling inductance and / or the size are preferably determined by means of a regression, in particular linear regression. Such a procedure ensures that values determined at different times are taken into account when determining the coupling inductance and / or the size. This increases the accuracy of the method.

According to a preferred embodiment, provision is made for the first current profile to be determined as a function of the first square current means or the first current amplitude and / or the second current profile to be determined as a function of the second square current means or the second current amplitude. This has the advantage that the first current profile and / or the second current profile are available, although these are not recorded. The method for determining the coupling inductance and / or the size can thus be carried out precisely on the one hand and on the other hand inexpensively.

The first voltage curve is preferably determined as a function of the first square voltage means or the first voltage amplitude. This also has the advantage that the method can be carried out precisely on the one hand and on the other hand inexpensively.

According to a preferred embodiment, at least two phase shifts are specified, each of which is a measure of a phase difference between the actual first voltage curve on the one hand and the first current curve or the second current curve on the other hand, a potential first voltage curve being determined as a function of the specified phase shifts. As described above, in particular the first square voltage means or the first voltage amplitude are determined as the first voltage value. In these cases, the actual phase difference between the first voltage curve and the first current curve or the second current curve cannot be seen from the measured values. By specifying at least two phase shifts, it is achieved that the coupling inductance and / or the size can also be determined if the actual phase difference is unknown.

According to a preferred embodiment, a potential coupling inductance and / or a potential variable proportional to the potential coupling inductance are determined as a function of each of the potential voltage curves determined. This has the advantage that, depending on the plurality of potential coupling inductances or potential sizes, it can be decided which of the potential coupling inductances or potential sizes at least substantially corresponds to the actual coupling inductance or size, and that this potential coupling inductance or potential size then as Coupling inductance or size can be selected.

In this case, a quality measure is preferably determined for each of the potential coupling inductances and / or potential variables, with one of the potential coupling inductances being selected as coupling inductance and / or one of the potential variables as a variable depending on the quality measures. This ensures that one of the potential coupling inductances is selected as the coupling inductance and / or one of the potential variables as a variable which at least substantially corresponds to the actual coupling inductor or the actual variable. Accordingly, the accuracy of the method is also increased by such a procedure. A coefficient of determination is preferably determined as a quality measure for each of the potential coupling inductances and / or potential variables.

The control device according to the invention for an energy transmission device, the first coil, a second coil that is electrically separated from the first coil, an alternating current or alternating voltage source that is electrically conductively connected to the first coil, a voltage measuring device that is designed to at least a first voltage value, in particular the first coil to determine a first current measuring device, which is designed to at least a first current value to determine the first coil and has a second current measuring device, which is designed to determine at least a second current value of the second coil, is characterized by the features of claim 13 in that the control device is specially designed for the intended use to carry out the method according to the invention. This results in the advantages already mentioned. Further preferred features and combinations of features result from what has been described above and from the claims.

• 1 eine Energieübertragungseinrichtung in einer schematischen Darstellung,
• 2 ein erstes Ausführungsbeispiel eines Verfahrens zum Ermitteln einer Koppelinduktivität der Energieübertragungseinrichtung und
• 3 ein zweites Ausführungsbeispiel des Verfahrens.

The invention is explained in more detail below with reference to the drawings, the same and corresponding elements in the figures being provided with the same reference symbols. Show this

• 1 an energy transmission device in a schematic representation,
• 2nd a first embodiment of a method for determining a coupling inductance of the energy transmission device and
• 3rd a second embodiment of the method.

1 shows an energy transmission device 1 in a schematic representation. The energy transfer device 1 has a first coil 2nd and one electrically from the first coil 2nd separate second coil 3rd on. The first coil is present 2nd Components of an inductive charging station 11 . The second coil 3rd is part of a mobile device that is electrically connected to the second coil 3rd connected energy storage 6 has, one between the energy storage 6 and the second coil 3rd arranged power electronics for reasons of clarity in 1 is not shown. In particular, the mobile device is a motor vehicle with an electric drive machine. At least one electrical resistance of the first coil is present 2nd and a self-inductance or self-inductance of the first coil 2nd known. The first coil 2nd is with an AC power source 4th the energy transmission device 1 connected. Alternatively, the energy transmission device has 1 one with the first coil 2nd connected AC voltage source. Is by the AC power source 4th an alternating current is applied to the first coil, so in the first coil 2nd a coil current and through the coil current or through the first coil 2nd a magnetic field 5 generated. The second coil 3rd is in the present case in the magnetic field 5 arranged that by the magnetic field 5 an electrical voltage in the second coil 3rd is induced. The energy storage is induced by the induced voltage 6 loaded. The second coil is alternatively or additionally 3rd connected or connectable to a consumer, with the in the second coil 3rd induced voltage of the consumer is operated or is operable.

The first coil 2nd are a first voltage measuring device 7 and a first current measuring device 8th assigned. The first voltage measuring device 7 is parallel to the first coil 2nd switched and designed to at least one voltage value of the first coil 2nd capture. The first current measuring device 8th is in line with the first coil 2nd switched and designed to at least a first current value of the first coil 2nd capture. In addition, the second coil is also 3rd an optional voltage measuring device, ie a second voltage measuring device 9 , and a current measuring device, ie a second current measuring device 10th , assigned. The second voltage measuring device 9 is parallel to the second coil 3rd switched and designed to at least one voltage value of the second coil 3rd capture. The second current measuring device 10th is in series with the second coil 3rd switched and designed to at least a second current value of the second coil 3rd capture.

In addition, the energy transmission device 1 a control unit 12th on. The control unit 12th is with the voltage measuring devices 7 and 9 and with the current measuring devices 8th and 10th communication-linked, so that the control unit 12th through the facilities 7 to 10th recorded values are available. The control unit is present 12th designed to depend on the voltage value of the first coil 2nd , the first current value, the second current value and the electrical resistance of the first coil 2nd and the self-inductance of the first coil 2nd the coupling inductance and / or the coupling factor of the energy transmission device 1 to determine. The control unit is alternative or additional 12th designed for the coupling inductance and / or the coupling factor as a function of the voltage value of the second coil 3rd , the first current value, the second current value and the electrical resistance of the second coil 3rd and the self-inductance of the second coil 3rd to determine. The voltage value that is taken into account when determining the coupling inductance and / or the size is referred to as the first voltage value.

The following are two exemplary embodiments of a method for determining the coupling inductance and / or the coupling factor of the energy transmission device 1 explained.

Dabei ist U₁(t) der Spannungswert der ersten Spule 2 zum Zeitpunkt t, R₁ der elektrische Widerstand der ersten Spule 2, h_1,coil(t) der erste Stromwert der ersten Spule 2 zum Zeitpunkt t, L₁ die Selbstinduktivität der ersten Spule 2, İ_1,coil(t) die Ableitung des ersten Stromwertes der ersten Spule 2 zum Zeitpunkt t und İ_2,coil(t) die Ableitung des zweiten Stromwertes der zweiten Spule 3 zum Zeitpunkt t.The coupling inductance M can be represented as follows according to equation (0.1): $$U_1\left(t\right)=R_1{\mathrm{I.}}_{\mathrm{1,}cOil}\left(t\right)+L_1{\dot{\mathrm{I.}}}_{\mathrm{1,}cOil}\left(t\right)-M{\dot{\mathrm{I.}}}_{\mathrm{2,}cOil}\left(t\right)$$

U ₁ (t) is the voltage value of the first coil 2nd at time t, R ₁ the electrical resistance of the first coil 2nd , h _{1, coil} (t) the first current value of the first coil 2nd at time t, L ₁ the self-inductance of the first coil 2nd , İ _{1, coil} (t) the derivative of the first current value of the first coil 2nd at times t and İ _{2, coil} (t) the derivative of the second current value of the second coil 3rd at time t.

Gemäß dem in 2 dargestellten ersten Ausführungsbeispiel des Verfahrens wird in einem Schritt S1 als erster Spannungswert ein erster Spannungsverlauf der ersten Spule 2, als erster Stromwert ein erster Stromverlauf der ersten Spule 2 und als zweiter Stromwert ein zweiter Stromverlauf der zweiten Spule 3 ermittelt. In einem Schritt S2 wird aus dem ersten Stromverlauf und aus dem zweiten Stromverlauf jeweils eine Ableitung ermittelt beziehungsweise berechnet. Demzufolge ist gemäß dem in 2 dargestellten Ausführungsbeispiel lediglich die Koppelinduktivität M eine Unbekannte in den Gleichungen (0.1) beziehungsweise (0.2).Equation (0.1) can be changed as follows: $$U_1\left(t\right)=R_1{\mathrm{I.}}_{\mathrm{1,}cOil}\left(t\right)+L_1{\dot{\mathrm{I.}}}_{\mathrm{1,}cOil}\left(t\right)-M{\dot{\mathrm{I.}}}_{\mathrm{2,}cOil}\left(t\right)$$

According to the in 2nd illustrated first embodiment of the method is in one step S1 a first voltage curve of the first coil as the first voltage value 2nd , a first current profile of the first coil as the first current value 2nd and as a second current value a second current profile of the second coil 3rd determined. In one step S2 a derivation is determined or calculated from the first current curve and from the second current curve. Accordingly, according to the in 2nd In the exemplary embodiment shown, only the coupling inductance M is unknown in equations (0.1) and (0.2).

mit $$y_i=U_{\mathrm{1,}i}-R_1{I}_{\mathrm{1,}coil,i}-L_1{\dot{I}}_{\mathrm{1,}coil,i}$$

und $$x_i=-{\dot{I}}_{\mathrm{2,}coil,i}$$

und $$\beta =M$$

Ziel ist es, mit n Messungen den unbekannten Koeffizienten β (also die Koppelinduktivität M) zu schätzen. Da der erste Spannungsverlauf, der erste Stromverlauf und der zweite Stromverlauf vorliegen, ist die Anzahl der Messungen zumindest größer als die Anzahl der einen Unbekannten. In einem Schritt S3 wird gemäß Gleichung (0.7) eine lineare Regression durchgeführt, wodurch die Unbekannte β, also die Koppelinduktivität M, ermittelt wird. Mittels einer linearen Regression kann bei derartigen Problemen eine zuverlässige Parameterschätzung für die Unbekannte β durchgeführt werden. $$\beta =\frac{{\displaystyle {\sum }_{i=1}^n\left(x_i-\overline{x}\right)\left(y_i-\overline{y}\right)}}{{\displaystyle {\sum }_{i=1}^n{\left(x_i-\overline{x}\right)}^2}}$$

Dabei wird y_i gemäß der oben stehenden Gleichung (0.4) berechnet und y ist gemäß Gleichung (0.8) das arithmetische Mittel der berechneten Werte: $$\overline{y}=\frac{1}{n}{\displaystyle {\sum }_{i=1}^n{y}_i}$$

Weiterhin wird x_i gemäß Gleichung (0.5) berechnet, und x ist das arithmetische Mittel der verwendeten Werte x_i.Because in the step S1 a first voltage curve, a first current curve and a second current curve are determined, there is a large number of first voltage values, first current values and second current values. In the case of n measurements, the equation (0.2) also applies to each individual measurement i = 1.2, ... n at the associated time t. This can be simplified as follows: $$y_i=\beta \cdot x_i$$

With $$y_i=U_{\mathrm{1,}i}-R_1{\mathrm{I.}}_{\mathrm{1,}cOil,i}-L_1{\dot{\mathrm{I.}}}_{\mathrm{1,}cOil,i}$$

and $$x_i=-{\dot{\mathrm{I.}}}_{\mathrm{2,}cOil,i}$$

and $$\beta =M$$

The aim is to estimate the unknown coefficient β (i.e. the coupling inductance M) with n measurements. Since the first voltage curve, the first current curve and the second current curve are present, the number of measurements is at least greater than the number of unknowns. In one step S3 a linear regression is carried out according to equation (0.7), whereby the unknown β, that is to say the coupling inductance M, is determined. In the case of such problems, linear regression can be used to perform a reliable parameter estimate for the unknown β. $$\beta =\frac{{\displaystyle {\sum }_{i=1}^n\left(x_i-\overline{x}\right)\left(y_i-\overline{y}\right)}}{{\displaystyle {\sum }_{i=1}^n{\left(x_i-\overline{x}\right)}^{\mathrm{2nd}}}}$$

Here y _{i is} calculated according to equation (0.4) above and y is the arithmetic mean of the calculated values according to equation (0.8): $$\overline{y}=\frac{1}{n}{\displaystyle {\sum }_{i=1}^n{y}_i}$$

Furthermore, x _{i is} calculated according to equation (0.5), and x is the arithmetic mean of the used values x _i .

Mittels der oben aufgeführten Gleichung (0.3) kann mit den Werten einer einzelnen Messung des ersten Spannungswertes, des ersten Stromwertes und des zweiten Stromwertes nach der Unbekannten β umgestellt und die Koppelinduktivität M berechnet werden. Der Vorteil des Verwendens von Werten mehrerer Messungen und das Durchführen der linearen Regression in dem Schritt S3 liegt darin, dass die Genauigkeit des Ermittelns der Koppelinduktivität beziehungsweise des Koppelfaktors gesteigert werden.In particular, in an optional step S4 from the coupling inductance M the coupling factor k of the energy transmission device 1 calculated. The following equation (0.9) is used for this, where L _{2 is} the self-inductance of the second coil 3rd and L _1, as described above, the self-inductance of the first coil 2nd is. $$k=\frac{M}{\sqrt{L_1{L}_{\mathrm{2nd}}}}$$

Using equation (0.3) listed above, the values of a single measurement of the first voltage value, the first current value and the second current value can be converted to the unknown β and the coupling inductance M can be calculated. The advantage of using values from multiple measurements and performing linear regression in the step S3 lies in the fact that the accuracy of determining the coupling inductance or the coupling factor is increased.

Regarding 3rd a second exemplary embodiment of the method is explained below. According to the second embodiment, in one step T1 a first quadratic voltage means is determined as the first voltage value, a first quadratic current means is determined as the first current value and a second quadratic current means is determined as the second current value. Alternatively, in the step T1 a first voltage amplitude as the first voltage value, a first current amplitude as the first current value and a second current amplitude as the second current value.

die bekannte Phasenverschiebung zwischen dem ersten Stromverlauf und dem zweiten Stromverlauf. Außerdem beschreibt f die vorliegend bekannte Frequenz der an der ersten Spule 2 angelegten Wechselspannung beziehungsweise des an der ersten Spule 2 angelegten Wechselstroms. Werden in dem Schritt T1 jedoch die erste Stromamplitude und die zweite Stromamplitude ermittelt, so wird in den Gleichungen (0.10) bis (0.13) anstelle des Produkts der quadratischen Strommittel mit der Quadratwurzel von 2 $\left(X_{RMS}\cdot \sqrt{2}\right)$

die jeweilige Amplitude X_max verwendet. $$I_{\mathrm{1,}coil}\left(t\right)=I_{\mathrm{1,}coil,RMS}\cdot \sqrt{2}\cdot \text{sin}\left(2\pi f\cdot t\right)$$

$$I_{\mathrm{2,}coil}\left(t\right)=I_{\mathrm{2,}coil,RMS}\cdot \sqrt{2}\cdot \text{sin}\left(2\pi f\cdot t+\frac{T}{4}\right)$$

In one step T2 a current profile is determined in each case from equations (0.10) and (0.11) from the first square current means and the second square current means. I _{1, coil, RMS describes} the first square current mean, I _{2, coil, RMS describes} the second square current mean and $\frac{T}{\mathrm{4th}}$

the known phase shift between the first current curve and the second current curve. In addition, f describes the presently known frequency of that on the first coil 2nd AC voltage applied or that of the first coil 2nd applied alternating current. Be in the step T1 however, the first current amplitude and the second current amplitude are determined, instead of the product of the quadratic current mean with the square root of 2 in equations (0.10) to (0.13) $\left(X_{RMS}\cdot \sqrt{\mathrm{2nd}}\right)$

the respective amplitude X _max used. $${\mathrm{I.}}_{\mathrm{1,}cOil}\left(t\right)={\mathrm{I.}}_{\mathrm{1,}cOil,RMS}\cdot \sqrt{\mathrm{2nd}}\cdot \text{sin}\left(\mathrm{2nd}\pi f\cdot t\right)$$

$${\mathrm{I.}}_{\mathrm{2,}cOil}\left(t\right)={\mathrm{I.}}_{\mathrm{2,}cOil,RMS}\cdot \sqrt{\mathrm{2nd}}\cdot \text{sin}\left(\mathrm{2nd}\pi f\cdot t+\frac{T}{\mathrm{4th}}\right)$$

$${\dot{I}}_{\mathrm{2,}coil}\left(t\right)=2\pi f\cdot I_{\mathrm{2,}coil,RMS}\cdot \sqrt{2}\cdot \text{cos}\left(2\pi f\cdot t+\frac{T}{4}\right)$$

Die tatsächliche Phasenverschiebung beziehungsweise Phasendifferenz zwischen dem ersten Spannungswert und dem ersten Stromwert beziehungsweise dem zweiten Stromwert ist in dem zweiten Ausführungsbeispiel des Verfahrens nicht bekannt. Um in Abhängigkeit von dem ersten quadratischen Spannungsmittel den ersten Spannungsverlauf zu ermitteln, werden in einem Schritt T4 mehrere Phasenverschiebungen α vorgegeben. In Abhängigkeit von jeder der Phasenverschiebungen α wird gemäß der nachfolgenden Gleichung (0.14) in einem Schritt T5 jeweils ein erster potentieller Spannungsverlauf ermittelt. Wird in dem Schritt T1 jedoch die erste Spannungsamplitude U_1,max ermittelt, so wird in Gleichung (0.14) anstelle des Produkts des ersten quadratischen Spannungsmittels mit der Quadratwurzel von 2 $\left(U_{\mathrm{1,}RMS}\cdot \sqrt{2}\right)$

die erste Spannungsamplitude U_1,max verwendet. $$U_1\left(t\right)=U_{\mathrm{1,}RMS}\cdot \sqrt{2}\cdot \text{sin}\left(2\pi f\cdot t+\frac{T}{4}+\alpha \right)$$

In einem Schritt T6 wird in Abhängigkeit von jedem der potentiellen Spannungsverläufe jeweils eine potentielle Koppelinduktivität unter Verwendung der linearen Regression gemäß Gleichung (0.7) ermittelt. Optional wird außerdem gemäß Gleichung (0.9) für jede der potentiellen Koppelinduktivitäten ein potentieller Koppelfaktor berechnet. In einem Schritt T7 wird für jede der Regressionsrechnungen aus T6 jeweils ein Bestimmtheitsmaß R² berechnet. Das Bestimmtheitsmaß R² spiegelt die Güte der Regression wieder und kann Werte zwischen 0 und 1 aufweisen. Ein Wert des Bestimmheitsmaßes nahe 1 bedeutet, dass die potentielle Koppelinduktivität beziehungsweise der potentielle Koppelfaktor der tatsächlichen Koppelinduktivität beziehungsweise dem tatsächlichen Koppelfaktor zumindest im Wesentlichen entspricht.In one step T3 a derivation of the first current profile and the second current profile is determined in accordance with equations (0.12) and (0.13). $${\dot{\mathrm{I.}}}_{\mathrm{1,}cOil}\left(t\right)=\mathrm{2nd}\pi f\cdot {\mathrm{I.}}_{\mathrm{1,}cOil,RMS}\cdot \sqrt{\mathrm{2nd}}\cdot \text{cos}\left(\mathrm{2nd}\pi f\cdot t\right)$$

$${\dot{\mathrm{I.}}}_{\mathrm{2,}cOil}\left(t\right)=\mathrm{2nd}\pi f\cdot {\mathrm{I.}}_{\mathrm{2,}cOil,RMS}\cdot \sqrt{\mathrm{2nd}}\cdot \text{cos}\left(\mathrm{2nd}\pi f\cdot t+\frac{T}{\mathrm{4th}}\right)$$

The actual phase shift or phase difference between the first voltage value and the first current value or the second current value is not known in the second exemplary embodiment of the method. In order to determine the first voltage curve as a function of the first square voltage means, in one step T4 several phase shifts α specified. Depending on each of the phase shifts, α is in one step according to equation (0.14) below T5 a first potential voltage curve is determined in each case. Will in the step T1 However, if the first voltage amplitude U _{1, max is} determined, then instead of the product of the first quadratic stress mean with the square root of 2, equation (0.14) $\left(U_{\mathrm{1,}RMS}\cdot \sqrt{\mathrm{2nd}}\right)$

the first voltage amplitude U _{1, max} used. $$U_1\left(t\right)=U_{\mathrm{1,}RMS}\cdot \sqrt{\mathrm{2nd}}\cdot \text{sin}\left(\mathrm{2nd}\pi f\cdot t+\frac{T}{\mathrm{4th}}+\alpha \right)$$

In one step T6 Depending on each of the potential voltage profiles, a potential coupling inductance is determined using the linear regression according to equation (0.7). Optionally, a potential coupling factor is also calculated according to equation (0.9) for each of the potential coupling inductances. In one step T7 a coefficient of determination R ^{2 is} calculated for each of the regression calculations from T6. The coefficient of determination R ² reflects the quality of the regression and can have values between 0 and 1. A value of the measure of determination close to 1 means that the potential coupling inductance or the potential coupling factor at least substantially corresponds to the actual coupling inductance or the actual coupling factor.

Dabei beschreibt ŷ_i gemäß Gleichung (0.16) den nach dem Regressionsmodell für den Zeitpunkt i berechneten Wert: $${\widehat{y}}_i=\beta \cdot x_i=-\beta \cdot {\dot{I}}_{\mathrm{2,}coil,i}$$

Aus dem Bestimmtheitsmaß R² lässt sich folgendes ableiten: Hat das Bestimmtheitsmaß den Wert 1, so bedeutet dies, dass die vorgegebene Phasenverschiebung korrekt ist. Des Weiteren ist in diesem Fall die zugehörige Schätzung der Koppelinduktivität beziehungsweise des Koppelfaktors korrekt.The coefficient of determination R ² is calculated as follows: $$R^{\mathrm{2nd}}=1-\frac{{\displaystyle {\sum }_{i=1}^n\left(y_i-{\widehat{y}}_i{}^{\mathrm{2nd}}\right)}}{{\displaystyle {\sum }_{i=1}^n\left(y_i-{\overline{y}}^{\mathrm{2nd}}\right)}}$$

According to equation (0.16), ŷ _i describes the value calculated for the time i according to the regression model: $${\widehat{y}}_i=\beta \cdot x_i=-\beta \cdot {\dot{\mathrm{I.}}}_{\mathrm{2,}cOil,i}$$

The following can be derived from the coefficient of determination R ² : The coefficient of determination has the value 1 , this means that the specified phase shift is correct. Furthermore, in this case the associated estimate of the coupling inductance or the coupling factor is correct.

In one step T8 the potential coupling inductance is selected as the coupling inductance and / or the potential coupling factor is selected as the coupling factor whose assigned coefficient of determination has the greatest value.

In particular, in the step T4 the multiple phase shifts are specified simultaneously and a potential coupling inductance, a potential coupling factor and a coefficient of determination are determined as a function of each of the phase shifts. Alternatively, in the step T4 Sequential phase shifts are specified in succession until, depending on one of the predetermined phase shifts, a coefficient of determination is determined which exceeds a predetermined threshold value. In the step T8 The potential coupling inductance and / or potential variable to which this coefficient of determination is assigned are then selected as the coupling inductance or variable (this procedure is indicated by the dashed arrow between the step T7 and the step T4 indicated).

In addition to those related to 1 and 2nd The exemplary embodiments described also exist in mixed forms of the methods 1 and 2nd . For example, according to a third exemplary embodiment, a first voltage curve is determined as the first voltage value and a quadratic current average or a current amplitude is determined as the first current value and second current value. According to a fourth exemplary embodiment, a first quadratic voltage means or a first quadratic voltage amplitude is determined as the first voltage value and a current profile is determined as the first current value and the second current value.

Dabei ist U₂(t) der Spannungswert der zweiten Spule 3 zum Zeitpunkt t und İ_2,coil(t) der zweite Stromwert der zweiten Spule 3 zum Zeitpunkt t. Insbesondere werden die Koppelinduktivität und/oder die Größe gemäß Gleichung (0.17) anstelle von Gleichung (0.1) ermittelt. Demnach werden die Koppelinduktivität und/oder die Größe dann in Abhängigkeit von dem elektrischen Widerstand der zweiten Spule 3, der Selbstinduktivität der zweiten Spule 3, dem Spannungswert der zweiten Spule 3, dem ersten Stromwert der ersten Spule 2 und dem zweiten Stromwert der zweiten Spule 3 ermittelt. Somit ist gemäß diesem Ausführungsbeispiel der Spannungswert der zweiten Spule 3 der erste Spannungswert.As an alternative to equation (0.1), the coupling inductance M can also be represented as follows according to equation (0.17): $$U_{\mathrm{2nd}}\left(t\right)=R_{\mathrm{2nd}}{\mathrm{I.}}_{\mathrm{2,}cOil}\left(t\right)+L_{\mathrm{2nd}}{\dot{\mathrm{I.}}}_{\mathrm{2,}cOil}\left(t\right)-M{\dot{\mathrm{I.}}}_{\mathrm{1,}cOil}\left(t\right)$$

U ₂ (t) is the voltage value of the second coil 3rd at time t and İ _{2, coil} (t) the second current value of the second coil 3rd at time t. In particular, the coupling inductance and / or the size are determined according to equation (0.17) instead of equation (0.1). Accordingly, the coupling inductance and / or the size are then dependent on the electrical resistance of the second coil 3rd , the self-inductance of the second coil 3rd , the voltage value of the second coil 3rd , the first current value of the first coil 2nd and the second current value of the second coil 3rd determined. Thus, according to this embodiment, the voltage value of the second coil 3rd the first voltage value.

Claims (13)

Method for determining a coupling inductance and / or a variable proportional to the coupling inductance, in particular a coupling factor, of an energy transmission device (1), the energy transmission device (1) comprising a first coil (2) and a second coil electrically separated from the first coil (2) (3), with the following steps: a) applying an electrical alternating voltage or an electrical alternating current to the first coil (2), b) determining at least a first voltage value of one of the coils (2, 3), at least a first current value of the first coil (2) and at least a second current value of the second coil (3), c) determining the coupling inductance and / or the size as a function of an electrical resistance of one of the coils (2, 3), a self-inductance of one of the coils (2, 3), the first voltage value, the first current value and the second current value. Procedure according to Claim 1 , characterized in that several first voltage values, several first current values and / or several second current values are determined and taken into account when determining the coupling inductance and / or the size. Method according to one of the preceding claims, characterized in that a first voltage profile is determined as the first voltage value, a first current profile as the first current value and / or a second current profile as the second current value. Method according to one of the preceding claims, characterized in that a first voltage amplitude is determined as the first voltage value, a first current amplitude as the first current value and / or a second current amplitude as the second current value. Method according to one of the preceding claims, characterized in that a first square voltage means is determined as the first voltage value, a first square current means as the first current value and / or a second square current means as the second current value. Method according to one of the preceding claims, characterized in that a first derivative and / or a second derivative is determined as a function of the first current value and / or a second derivative is determined as a function of the first derivative and / or the second derivative Coupling inductance and / or the size is determined. Method according to one of the preceding claims, characterized in that the coupling inductance and / or the size are determined by means of a regression, in particular linear regression. Procedure according to one of the Claims 4 to 7 , characterized in that, depending on the first square current mean or the first current amplitude, the first current profile and / or the second current profile is determined as a function of the second square current means or the second current amplitude. Procedure according to one of the Claims 4 to 8th , characterized in that the first voltage curve is determined as a function of the first square voltage means or the first voltage amplitude. Procedure according to Claim 9 , characterized in that at least two phase shifts are specified, each of which is a measure of a phase difference between the first voltage curve on the one hand and the first current curve or the second current curve on the other hand, a potential first voltage curve being determined in each case as a function of the predetermined phase shifts. Procedure according to Claim 10 , characterized in that depending on each of the potential first voltage curves determined, a potential coupling inductance and / or a potential variable proportional to the potential coupling inductance are determined. Procedure according to Claim 11 , characterized in that a quality measure is determined in each case for each of the potential coupling inductances and / or potential quantities, one of the potential coupling inductances being selected as the coupling inductance and / or one of the potential quantities as a quantity depending on the quality measurements. Control device (12) for an energy transmission device (1), which has a first coil (2), a second coil (3) which is electrically separated from the first coil (2), and an alternating current or alternating voltage source which is electrically conductively connected to the first coil (2) (4), a voltage measuring device (7, 9), which is designed to determine at least a first voltage value of one of the coils (2, 3), a first current measuring device (8), which is designed to at least a first current value of the first Determine coil (2), and has a second current measuring device (10), which is designed to determine at least a second current value of the second coil (3), characterized in that the control device (12) is specially prepared for Intended use the method according to one of the Claims 1 to 12th perform.

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