Measuring transducer for electric vehicles and a method of operating a measuring transducer

Abstract

Measuring transducer for electric vehicles having at least one tap arranged to tap at least one AC measurement value in an AC charging circuit, a transformer arranged to convert a frequency of the AC measurement value into a standard frequency of an energy supply grid and to output at least one AC measurement value with the standard frequency in an AC measuring circuit, and at least one standard meter arranged in the AC measuring circuit for detecting an electrical power with the AC measurement value at the standard frequency.

Claims

1. An electric vehicle, comprising: an induction coil in an AC charging circuit for inductive coupling with a charging station and for receiving electrical power via an excitation coil for charging an energy storage, and a measuring transducer comprising: at least one tap arranged to tap at least one AC measured value in an AC charging circuit which comprises the induction coil, a converter arranged for converting a frequency of the AC measured value into a standard frequency of a energy supply grid, and for outputting at least one AC value with the standard frequency into an AC measuring circuit, and at least one standard meter arranged in the AC measuring circuit for obtaining an electrical power using the AC value at the standard frequency.

2. The electric vehicle according to claim 1, wherein the AC charging circuit has at least one induction coil as a constant voltage source.

3. The electric vehicle according to claim 1, wherein the converter sets an AC control value at least as a function of the AC measured value and outputs the AC value as a function of the AC control value.

4. The electric vehicle according to claim 1, wherein the at least one AC measured value comprises at least one alternating voltage and/or one alternating current and in that the at least one AC value comprises at least one alternating voltage and/or one alternating current at standard frequency.

5. The electric vehicle according to claim 1, wherein that the electrical power measured is an active electrical power.

6. The electric vehicle according to claim 1, wherein that the standard meter is in particular a Ferraris Meter or a Smart Meter.

7. The electric vehicle according to claim 1, wherein the tap is arranged parallel to at least one measuring resistor.

8. The electric vehicle according to claim 1, wherein a frequency in the AC charging circuit deviates from a standard frequency of an energy supply grid and in that the standard frequency in the AC measuring circuit is in particular 50 Hz or 60 Hz +/3%.

9. The electric vehicle according to claim 1, wherein the constant current source has at least one resistance which can be set as a function of the AC control value.

10. The electric vehicle according to claim 1, wherein that the AC measuring circuit is a single-phase AC circuit.

11. An electric vehicle, comprising: an induction coil in an AC charging circuit for inductive coupling with a charging station and for receiving electrical power via an excitation coil for charging an energy storage, and a measuring transducer comprising: at least one tap arranged to tap at least one AC measured value in an AC charging circuit which comprises the induction coil, a converter arranged for converting a frequency of the AC measured value into a standard frequency of a energy supply grid, and for outputting at least one AC value with the standard frequency into an AC measuring circuit, and at least one standard meter arranged in the AC measuring circuit for obtaining an electrical power using the AC value at the standard frequency; wherein the converter arranged in such a way that the absolute value of the AC value is smaller by at least a factor of ten than the absolute value of the AC measured value.

12. An electric vehicle, comprising: an induction coil in an AC charging circuit for inductive coupling with a charging station and for receiving electrical power via an excitation coil for charging an energy storage, and a measuring transducer comprising: at least one tap arranged to tap at least one AC measured value in an AC charging circuit which comprises the induction coil, a converter arranged for converting a frequency of the AC measured value into a standard frequency of a energy supply grid, and for outputting at least one AC value with the standard frequency into an AC measuring circuit, and at least one standard meter arranged in the AC measuring circuit for obtaining an electrical power using the AC value at the standard frequency; wherein at least one absolute value of the alternating current in the AC charging circuit and an absolute value of a voltage across an energy storage in the AC charging circuit can be detected via the tap as AC measured values.

13. An electric vehicle, comprising: an induction coil in an AC charging circuit for inductive coupling with a charging station and for receiving electrical power via an excitation coil for charging an energy storage, and a measuring transducer comprising: at least one tap arranged to tap at least one AC measured value in an AC charging circuit which comprises the induction coil, a converter arranged for converting a frequency of the AC measured value into a standard frequency of a energy supply grid, and for outputting at least one AC value with the standard frequency into an AC measuring circuit, and at least one standard meter arranged in the AC measuring circuit for obtaining an electrical power using the AC value at the standard frequency; wherein the AC current measuring circuit has a constant current source and in that the constant current source feeds a constant alternating current into the AC current measuring circuit as a function of the AC current control value.

14. An electric vehicle, comprising: an induction coil in an AC charging circuit for inductive coupling with a charging station and for receiving electrical power via an excitation coil for charging an energy storage, and a measuring transducer comprising: at least one tap arranged to tap at least one AC measured value in an AC charging circuit which comprises the induction coil, a converter arranged for converting a frequency of the AC measured value into a standard frequency of a energy supply grid, and for outputting at least one AC value with the standard frequency into an AC measuring circuit, and at least one standard meter arranged in the AC measuring circuit for obtaining an electrical power using the AC value at the standard frequency; wherein the converter sets the AC value in such a way that the active electrical power in the AC measuring circuit is a constant factor smaller than the electrical power in the AC charging circuit.

15. A charging station, comprising: an excitation coil within an AC charging circuit and arranged for inductive coupling with an electric vehicle and for feeding an induction coil of the electric vehicle and a measuring transducer comprising: at least one tap arranged to tap at least one AC measured value in an AC charging circuit which comprises the induction coil, a converter arranged for converting a frequency of the AC measured value into a standard frequency of a energy supply grid, and for outputting at least one AC value with the standard frequency into an AC measuring circuit, and at least one standard meter arranged in the AC measuring circuit for obtaining an electrical power using the AC value at the standard frequency.

16. A method for operating an electric vehicle or a charging station, comprising the steps of: measuring at least one AC measured value in an AC charging circuit comprising an induction coil of an electric vehicle or an excitation coil of a charging station, and operating an AC measuring circuit using an AC value, wherein the AC value is fed into the AC measuring circuit at a standard frequency which is different from the frequency of the AC charging circuit, and wherein, within the AC measuring circuit, a standard meter obtains the AC value at the standard frequency.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) In the following, the subject matter is explained in more detail using a drawing showing embodiments. In the drawing show:

(2) FIG. 1 shows an AC charging circuit in an electric vehicle;

(3) FIG. 2 shows a transducer; and

(4) FIG. 3 shows an AC measuring circuit.

DETAILED DESCRIPTION

(5) FIG. 1 schematically shows the structure in an electric vehicle 2 with an induction coil 4. An alternating voltage is applied to the induction coil 4 at terminals 4a, 4b, via which an energy storage of the electric vehicle can be charged. For this purpose, an AC/DC transducer 6 is connected to the AC charging circuit, which is arranged to supply the energy storage 10. The charging process in the AC charging circuit 8 can be set via a charging controller, in particular the AC current in the AC charging circuit 8 can be set. The AC charging circuit 8 is usually designed for powers of more than 10 kW, preferably more than 40 kW, in particular more than 70 kW electrical power. The induction coil 4 is coupled to an excitation coil 5 of a charging station and electrical power is coupled into the AC charging circuit 8 via the magnetic coupling.

(6) For the sake of clarity, the AC charging circuit 8 is only shown with the measuring equipment relevant for the measuring transducer according to the subject-matter. Charging an electric vehicle naturally requires additional technical equipment, which is not shown here for the sake of clarity.

(7) A measuring resistor 12 is provided in the AC charging circuit 8. The measuring resistor 12 is usually a measuring shunt which has a constant current/voltage curve over a wide temperature range. The measuring shunt can be made of for example Manganin.

(8) The measuring resistor 12 taps the voltage drop with a voltmeter 13. From this voltage value, the amperage in the AC charging circuit 8 can be derived if both the temperature and the current-voltage characteristic of the measuring resistor 12 are known. This value is output as an AC measurement value 20.

(9) In addition, an alternating voltage is measured by a voltmeter 16b across load 6 and output as an alternating voltage measurement value 22.

(10) In addition, a temperature sensor 14 is provided, which is preferably arranged directly on the measuring resistor 12 and thus preferably measures the temperature of the measuring resistor 12. The temperature sensor 14 outputs a measured temperature value of 24.

(11) The measurement values measured in the AC charging circuit 8 are then first fed to a scaling device 30, as shown in FIG. 2.

(12) In the scaling device 30, in particular the AC measurement value 20 and the alternating voltage measurement value 22 are scaled in order to ensure in particular a lower amplitude of the measurement values in terms of absolute amount. Scaling can be carried out for one, several or all measurement values. In addition, a power measurement value 26 is fed back to the scaler 30, which is recorded as described below.

(13) All measurement values are then fed to an analog-to-digital transducer 32 and the then digitized measurement values are then fed to a transducer 34. In transducer 34, the AC measurement values are converted into an AC output value 28 as a function of the temperature measurement value 24 and the feedback power measured value 26.

(14) First, the alternating voltage value 22 and the AC current value 20 are used to determine an electrical power in the AC charging circuit 8. After or before this, the measured temperature value 24 can be used to calculate a temperature drift from the AC measurement value 20. If the measuring resistor 12 does not have a constant current/voltage characteristic curve over the entire temperature range, a temperature drift can be taken into account on the basis of the temperature measured value and the voltage actually flowing in the AC charging circuit 8 can thus be determined from the voltage measured via the resistor 12. After temperature adjustment, the charging power in the AC charging circuit 8 can then be determined.

(15) In addition, the frequency in the AC charging circuit 8 can be determined. Furthermore, the phase position can be determined from the charge current and charge voltage in order to determine the active power in charge circuit 8.

(16) Depending on a factor, for example 1.000, an AC control value can be determined. The factor can be applied, for example, to the charging power. If, for example, the charging power is 1 kW, given a factor of 1,000, the AC control value results in 1 W. A linear conversion of the AC measurement value into an AC control value is preferred.

(17) The AC control value 28 is output at transducer 34 and is used, for example, to convert to an AC current at a standard frequency.

(18) The AC control value 28 is fed to a constant current source 36, as shown in FIG. 3. The constant current source 36 usually has an adjustable resistor. The current can be adjusted via the constant current source 36 via the resistor. The resistance, which is set in the constant current source 36, is determined by the voltage in the AC measuring circuit 38 and the AC control value 28. If, for example, the electrical power in the charging circuit 8 is 23 kW, an AC power of 23 W results with a factor of 1,000 in the transducer 34. With an alternating voltage of 230 V AC at standard frequency and a power factor cosphi of 1, this results in an AC current value of 0.1 ampere. This amperage leads to an adjustment of the resistance in the constant current source 36 to 2.3 k. It should be mentioned that this is purely exemplary and that the constant current source 36 can also be operated with other values depending on the factor and other boundary conditions.

(19) The frequency of the AC values is preferably set to a standard value of 50 Hz or 60 Hz.

(20) The AC measuring circuit 38 is in particular a single-phase measuring circuit and has a standard meter 42 in addition to the constant current source 36. The standard meter 42 meters in particular the active electrical power or active energy consumed in the AC measuring circuit 38 at standard frequency. Please note that the standard meter 42 as the electricity meter is set to a standard frequency and only measures correctly at standard frequency. The standard frequency is usually 50 Hz or 60 Hz, depending on the electrical energy supply grid.

(21) In the above example, the power is 23 W, for example. If this occurs constantly for over an hour, i.e. if the vehicle is constantly charging with 23 kW for over an hour, for example, and has thus obtained an electrical energy of 23 kWh, the standard meter 42 measures 23 Wh. However, the measured value output could be 23 kWh if the energy meter 42 has a corresponding conversion factor of 1,000.

(22) To check the active power consumed in the AC measuring circuit 38 in relation to the electrical power in the AC charging circuit 8, a current and a voltage are metered in the AC measuring circuit 38. The current in the AC measuring circuit 38 is preferably measured via a voltmeter 44, which measures the voltage drop via the constant current source 36. The alternating voltage is measured by a voltmeter 46. In addition, a phase angle between current and voltage can be detected. The measured values derived from this are fed to an evaluation circuit 48 and in the evaluation circuit 48 the active power consumed in the AC measuring circuit 38 is determined on the basis of the measured values. This active power can be coupled-out as power measured value 26 and fed to the scale 30 as shown in FIG. 2.

(23) Finally, the measured power value 26 is fed to the transducer 34 and can be compared with the AC control value. These two values must correspond to each other, otherwise a control, in particular a P control, a PI control or a PID control can be carried out in the transducer 34 in order to achieve a synchronism from the measured AC measurement value and the set AC value.

(24) With the help of the measuring transducer, it is possible to meter measurement values relevant for billing purposes at a standard meter at standard frequency in a particularly simple and cost-effective way.

(25) All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

(26) The use of the terms a and an and the and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms comprising, having, including, and containing are to be construed as open-ended terms (i.e., meaning including, but not limited to,) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., such as) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

(27) Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.