WO2024261194A1 - Method for controlling an electrical energy transfer device based on induction - Google Patents

Abstract

The invention relates to a method for controlling an electrical energy transfer device based on induction, comprising: o a primary circuit (20) comprising: ■ an inverter (22) having a phase shift Phi and delivering a voltage injection frequency Fin, the inverter (22) being able to be connected to a voltage grid (2), ■ a primary inductive cell (24) able to be connected to the terminals of the inverter (22), comprising a first capacitor (26) and a first inductor (28), o a secondary circuit (40) comprising: ■ a voltage rectifier (42) able to be connected to an electrical energy storage unit (4) and to match an impedance Rref on its AC input independently of the impedance of the electrical energy storage unit (4), ■ a secondary inductive cell (44) able to be connected to the terminals of the voltage rectifier (42), comprising a second capacitor (46) and a second inductor (48), the method comprising the following steps: fixing the values of two parameters among Phi, F_in and R_ref, modulating the value of the parameter that has not been fixed.

Description

Description

Title of the invention: Method for controlling an electrical energy transfer device by induction

The present invention relates to a method of controlling an inductive electrical energy transfer device of a vehicle electrical energy storage unit.

The electrical energy storage unit has, for example, a nominal voltage of 12V, 48V, 60V or more, for example greater than 300V, for example 400V, 800V or 1000V

It is known to electrically power a vehicle electrical energy storage unit by contactless transmission by inductive coupling at a power of between 3 and 50 kW, when the vehicle is stationary or when it is moving. This power supply by contactless transmission is then done by means of magnetically coupled remote electrical circuits tuned to the same resonant frequency. The magnetically coupled circuits each implement an LC-type resonant cell.

The solution according to the application filed in France under No. 22 09978 on 09/30/2022 which is not part of the state of the art consists in applying an alternating voltage to the terminals of a primary inductive cell coupled by inductive coupling to a secondary inductive cell which, by impedance adaptation, makes it possible to transmit low-frequency electrical energy into an electrical energy storage unit, for example an electric vehicle battery. In this solution, the system comprises:

- a low-frequency inverter working at a switching frequency of between 50Hz and 5kHz, this inverter being for example controlled by phase shift Phi and connected to the terminals of the primary inductive cell, and

- a rectification stage performing an impedance adaptation connected to the terminals of the secondary inductive cell.

The system presents three input parameters for its command:

- End, the frequency of voltage injection at the terminals of the primary inductive cell, which is the frequency of the alternating voltage on the AC output of the inverter;

- Phi, the phase shift of the inverter that regulates the effective voltage across the primary inductive cell. For example, for a phase-shift controlled inverter with two switching arms, Phi is the phase shift between: controlling a switch connected to a DC terminal and belonging to one of the two switching arms, and the control of a switch connected to this same DC terminal and belonging to the other of the two switching arms; and

- R _re f, the equivalent load impedance imposed on the secondary inductive cell, R _re f being the reference impedance value for driving the rectifier stage performing the impedance matching. This equivalent impedance R _re f is for example expressed according to the equation

[Math 1] U = Imes * Rref, with Imes the current flowing in the secondary inductive cell and U the voltage measured between the two midpoints when the rectifier stage performing the impedance matching comprises two switching arms in parallel, each of these switching arms having an AC input at a midpoint between two static switches of this switching arm, the secondary inductive cell being mounted between these two midpoints.

In this solution, it is difficult to determine which values to choose for these three parameters when transferring electrical energy by inductive coupling.

There is therefore a need for a method of controlling an electrical energy transfer device by induction, improving the consideration of these three parameters Fin, Phi and Rref.

The invention aims to meet this need and achieves this, according to one of its aspects, using a method of controlling an electrical energy transfer device by induction comprising: o a primary circuit comprising:

■ an inverter controlled by phase shift Phi and providing a voltage injection frequency Fin, the inverter being capable of being connected to a voltage network, if necessary via a rectifier mounted in series between this voltage network and this inverter,

■ a primary inductive cell capable of being connected to the terminals of the inverter, comprising a first capacitor and a first inductance, o a secondary circuit comprising:

■ a voltage rectifier capable of being connected to an electrical energy storage unit and of carrying out an adaptation of impedance R _ref on its alternating input independently of the impedance of the electrical energy storage unit,

■ a secondary inductive cell capable of being connected to the terminals of the voltage rectifier, comprising a second capacitor and a second inductance, the method comprising the following steps: fixing the values of two parameters among Phi, Fin and R _re f, and modulating the value of the parameter not having been fixed.

The invention as defined above makes it possible to determine the power and efficiency of the electrical energy transfer for each set of values of the parameters Phi, Fin and R _re f. The proposed strategy makes it possible to set two parameters among the three to achieve the best performance and compensate for system variations (such as component drift, inductance misalignment), and modulate the third parameter to regulate the transmitted power according to this performance, in efficiency for example.

It also allows to maximize the transmitted power during energy transfer by inductive coupling as well as to maximize the efficiency of the energy transfer according to the transmitted power level when the value of one or two parameters among Phi, Fin and R _re f are fixed, the performance criteria being different according to the fixed parameters.

Regulating only one parameter while fixing the other two among Phi, Fin and Rref makes it possible to simplify the regulation carried out. For example, the parameters whose values are fixed are Fin and _Rref , or Fin and Phi, or _Rref and Phi. The parameter whose value is modulated can vary within a predefined range of values, this range of values remaining fixed during modulation or can vary dynamically.

Also, the value of a parameter can be set to a value within a given range. For example, the value of Phi is set to any value between 0° and 180°, for example, to a value greater than or equal to 175° and less than or equal to 180°.

According to a first example of implementation of the invention, the parameters whose values are fixed are Fin and R _ref . This first example of implementation makes it possible to obtain an efficiency between the power seen by the load R _ref and the power supplied at the output of the inverter maximized regardless of the level of power transmitted, therefore including the low powers, i.e. from 0W to the maximum power achievable in the system configuration.

According to this first example of implementation, the method according to the invention can comprise a step of fixing the value of the voltage injection frequency Fin to the value of the resonance frequency, that is to say to the frequency value giving a maximum effective value of the current in the inverter at given Phi and R _ref . The value of Phi being modulated according to this first example of implementation, in this step of fixing the value of Fin, the resonance frequency is determined by arbitrarily fixing a value for Phi and for R _ref and by scanning in frequency.

According to this first example of implementation, the method according to the invention can comprise another step of fixing the value of the impedance R _re f on the alternating input of the rectifier as a function of the values of the capacitance of the second capacitor, of the second inductance and of the coupling rate K of the primary and secondary inductive cells at given Phi and Fin. Here again an arbitrary value is fixed for Phi before modulation.

Once this fixing of the values of Fin and R _ref is done, we can proceed to the Phi modulation step.

According to a second example of implementation of the invention, the parameters whose values are fixed are Fin and Phi. This second example of implementation can make it possible to obtain optimal efficiency for high powers, for example for powers greater than or equal to 1 kW.

According to this second example of implementation, the method according to the invention can comprise a step of fixing the value of the voltage injection frequency Fin to the value of the resonance frequency, that is to say to the value of the frequency giving a maximum effective value of the current in the inverter at Phi and R _re f given. The value of R _re f being modulated according to this second example of implementation, it is chosen for this step at a low value, for example as being less than or equal to 10 Ohms. This value of R _re f is then modulated, in accordance with this second example of implementation. According to another step, the value of Phi can be fixed at any value between 0° and 180°. Once this fixing of the values of Fin and Phi has been carried out, the step of modulating R _re f can be carried out.

According to a third implementation example, the parameters whose values are fixed are R _ref and Phi. Similar to the second example, this third implementation example can achieve optimal efficiency for high powers. According to this third example of implementation, the method according to the invention can comprise a step of fixing the value of R _re f and/or Phi.

According to this third implementation example, the value of Phi can be set to any value between 0° and 180°. Once this setting of the values of R _ref and Phi is done, we can proceed to the Fin modulation step.

For the purposes of this application, “an inductive cell is capable of being connected to the terminals of an inverter or a rectifier” means that it is capable of being mounted between two midpoints belonging respectively to two switching arms of the inverter or the rectifier.

In all of the above, the method may consist in successively using one of the first, second and third implementation examples above and then another of the first, second and third implementation examples above. The control of the electrical energy transfer device by induction is thus adapted to the step of charging the electrical energy storage unit, for example depending on whether a step of initializing the charge, a step of charging at low power, a step of charging at low voltage of the electrical energy storage unit, a step of charging at high power, etc. are carried out.

As an example, for a low voltage charging step of the electrical energy storage unit, we proceed according to the second implementation example, with a value of Phi set at 180°, a value determined for the frequency Fin, then a modulation of R _re f to reach the expected power.

The electrical voltage network provides, for example, a nominal effective voltage of 230V or 110V with a frequency of 50 Hz or 60 Hz. The electrical network is, for example, single-phase.

The electricity grid is, for example, a regional or national electricity grid. It can be an independent local network, for example, including one or more batteries powered by energy sources such as wind turbines, solar panels, fuel cells or hydroelectric generators.

Typically, the electrical energy storage unit may be a lithium-ion type battery. This battery has for example a nominal voltage of 12V, 48V, 60V or more, for example greater than 300V, for example 400V, 800V or 1000V.

In order to allow a contactless exchange of electrical energy between the primary circuit and the secondary circuit, the inductive cell of the primary circuit and the inductive cell of the secondary circuit are configured to exchange electrical energy without contact by inductive coupling.

The primary inductive cell may include a coil for generating magnetic energy and the secondary inductive cell may include a coil for harvesting magnetic energy from the primary inductive cell.

The contactless exchange by inductive coupling of electrical energy is carried out for example at a frequency lower than 10 kHz, for example 7 kHz, for example 5 kHz, for example lower than 3kHz, or even lower than 2kHz or 1kHz, in particular still substantially equal to 400 Hz or 50 Hz.

Alternatively, the contactless exchange by inductive coupling of electrical energy can be done at a frequency of 85 kHz.In all of the above, the electrical energy transfer device can be controlled so as to selectively perform:

- a charge of the electrical energy storage unit from the voltage network, or

- a load of the voltage network from the electrical energy storage unit.

Thus, depending on the need, the exchange of electrical energy can be carried out in one direction or the other. Each of the inverter and the rectifier can implement controllable electronic switches. Each controllable electronic switch is for example a transistor, for example bipolar, MOS or IGBT, or a thyristor. Each controllable electronic switch is for example bidirectional.

The invention also relates, according to another of its aspects, to a device for transferring electrical energy by induction, comprising a control unit implementing the above method. The control unit may be a digital processing circuit, for example an ASIC type integrated circuit ("Application-specific integrated circuit" in English) or a microcontroller.

The control unit comprises, for example, a primary circuit control module and a secondary circuit control module.

When the voltage rectifier performing impedance matching comprises two switching arms in parallel, this impedance matching can be performed as follows. One of the first and second switching arms can switch at the frequency of the contactless exchanged energy, and the other of the first and second arms can switch at a higher frequency, for example equal to or greater than 5 times or 10 times the contactless exchange frequency. For example, one of the switching arms switches at the frequency of the contactless exchanged energy with a duty cycle of 50%, and the other switching arm switches at a frequency equal to or greater than greater than that of the energy transmitted from the primary circuit, in particular equal to or greater than 5 times or 10 times the frequency of the energy transmitted from the primary circuit, and with a duty cycle modulated according to the measured alternating current and the voltage on the alternating input of the two switching arms. This embodiment of impedance matching by the two switching arms of the voltage rectifier is for example as described in the Applicant's application FR 3 140 490. The content of this application is incorporated by reference into the present application, with regard to the manner of controlling two switching arms between the midpoints of which an inductive cell is mounted to perform the impedance matching.

The invention also relates, according to another of its aspects, to a component for the electrical power supply of an electrical energy storage unit, comprising the device for transferring electrical energy by induction as defined above, the component defining in particular a structure supporting the primary circuit and the secondary circuit in a rigidly coupled manner. Such a component is commonly called an “on-board charger”. This component is capable of being embedded in a hybrid or electric vehicle.

The invention also relates, according to another of its aspects, to a device for supplying electricity to an electrical energy storage unit, comprising:

- a charging terminal for a hybrid or electric vehicle, in which is arranged or to which is connected the primary circuit of the device for transferring electrical energy by induction as defined above, and

- a component capable of being embedded in a hybrid or electric vehicle, in which the secondary circuit of the electrical energy transfer device by induction as defined above is arranged.

This terminal then receives electrical energy from an electrical network via a cable which can be a single-phase cable or a three-phase cable. In this case, the primary circuit and the secondary circuit are not integrated into the same physical component.

The invention may be better understood by reading the following description of a non-limiting example of its implementation and by examining the attached drawing in which:

[Fig. l] schematically represents an electrical circuit according to an exemplary implementation of the invention,

[Fig.2] represents the power delivered (a) and the efficiency (b) of the energy transfer by inductive coupling according to a first control method, Fin being fixed. [Fig.3] represents the power delivered (a) and the efficiency (b) of the energy transfer by inductive coupling according to a second control method, Phi being fixed.

[Fig.4] represents the power delivered (a) and the efficiency (b) of the energy transfer by inductive coupling according to a third control method, R _ref being fixed.

Figure 1 shows a device for transferring electrical energy by induction 1 comprising: o a primary circuit 20 comprising:

■ a block 22 composed of a voltage rectifier connected in series to a phase-shift inverter Phi and providing a voltage injection frequency Fin, the voltage rectifier being connected to a voltage network 2,

■ a primary inductive cell 24 is connected to the terminals of the inverter and comprises a first capacitor 26 and a first inductance 28, o a secondary circuit 40 comprising:

■ a voltage rectifier 42 connected to an electrical energy storage unit 4 and performing an impedance adaptation R _ref on its alternating input independently of the impedance of the electrical energy storage unit,

■ a secondary inductive cell 44 connected to the terminals of the voltage rectifier, and comprising a second capacitor 46 and a second inductance 48.

The device 1 powers an electrical energy storage unit 4 which is for example a vehicle battery, which may have a nominal voltage of 48V, 60V, 300V, 400V, 800V or more. This battery is used to power an electric or hybrid vehicle propulsion system.

As shown in FIG. 1, the inductive cells 24 and 44 each comprise a capacitor and an inductor. The inductor may be a coil. The coil enables the generation of magnetic energy and has, for example, an inductance of between ImH and lOOmH. The capacitor has, for example, a capacitance of between lOOpF and lOOmF.

The three parameters, namely the voltage injection frequency Fin, the phase shift Phi of the inverter, and the impedance adaptation R _ref , can be modulated between two value limits (F i _n min/Fin max, Phi min/Phi max and RR _e f min/RR _e f max) in such a way that independent or combined in order to regulate a power P to be transmitted from the voltage Vdc supplying the inverter to the electrical storage unit 4 or vice versa and to determine the efficiency r of the transfer.

The inverter can be controlled in phase shift Phi or in pulse width modulation (Phi then corresponding to the difference in duty cycle al-a2 between the two arms, this difference varying over time).

One parameter among Phi, Fin and R _ref is modulated during the determination of the transmitted power P and the transfer efficiency r while the values of the second and third parameters are fixed.

Figures 2 to 4 show different methods of determining the power transferred by inductive coupling as a function of the value of two parameters among Phi, Fin and R _re f, the value of the third parameter being fixed.

In each of these three cases, the power received by battery 4 and the theoretical energy transfer efficiency are represented in the form of a graph with 2 input dimensions and one output dimension. In light are the high values and in dark are the low values. Phi is expressed in degrees, Fin in Hz and R _ref in ohms.

The value of the Fin parameter is fixed while the values of the Phi, and R _ref parameters are modulated in Figure 2 representing a first control method not covered by the claims.

The value of the parameter Phi is fixed while the values of the parameters Fin, and R _re f are modulated in Figure 3 representing a second control method not covered by the claims.

The value of the parameter R _re f is fixed while the values of the parameters Fin, and Phi are modulated in Figure 4 representing a third control method not covered by the claims.

According to the invention, to obtain simplified regulation, the value of a single parameter is modulated while the values of the other two parameters are fixed, for example the values of the parameters Phi and R _re f or Fin and R _re f or Fin and Phi are fixed while the values of the parameters Fin, Phi, R _re f are modulated respectively.

When modulating Phi, the method includes a step of setting the value of the voltage injection frequency Fin as the value of the resonance frequency, i.e. the value of the frequency giving a maximum effective value of the current in the inverter at fixed Phi and R _ref . The method also includes in this example a step of fixing the value of R _re f as a function of the values of the capacitance of the second capacitor, of the second inductance and of the coupling rate K of the first and second inductive cells at fixed Phi and Fin.

The value of Phi can be set to any value between 0° and 180°.

When the value of a parameter is fixed, this implies knowing its value beforehand before starting the power transmission in order to determine the optimal values of the other parameters. The following paragraphs describe how, according to an example, the optimal value of a parameter can be fixed before determining the optimal values of the other parameters.

The optimum value of the voltage injection frequency Fin is the value of the resonance frequency on the primary mesh composed of the inverter of block 22, the first capacitor 26 and the first inductance 28. The nominal theoretical value for this optimum value of the frequency Fin is:

Lp being the inductance value of the first inductor 28 and Cp the capacitance of the first capacitor 26.

_ r^ef “J Cs The optimum nominal value of R _re f is a function of the parameters of the circuit components, namely Ls, the inductance value of the second inductor 48, and Cs, the capacitance of the second capacitor 46, but also of the coupling rate K of the first and second inductive cells. The nominal theoretical value for this optimum value is: nnom _

_ r ^ef “J Cs

K being the coupling rate of the primary 28 and secondary 48 inductances.

Ls being the inductance value of the second inductor 48 and Cs the capacitance of the second capacitor 26.

This value will therefore vary according to the height of the vehicle from the ground, but also with the alignment precision between the primary and secondary inductive cells. Depending on the variability of the Ls, Cs and K parameters, it is possible to readjust this value with a calibration step of a regulation software before and periodically during the energy conversion.

The invention has been described above, without limitation of the general inventive concept. The invention applies for example also when the inverter is not a phase-shift controlled inverter but is a pulse width modulation controlled inverter. In the case where two switching arms are present, the above quantity Phi corresponds to the duty cycle difference al-a2, al being the duty cycle used to control the first switching arm and a2 being the duty cycle used to control the second switching arm, these duty cycles varying over time.

Many other modifications and variations will suggest themselves to those skilled in the art, after reflection on the various embodiments illustrated in this application.

These embodiments are given by way of example and are not intended to limit the scope of the invention, which is determined exclusively by the claims below.

According to another uncovered embodiment, two of the parameters among Phi, Fin and R _ref can be modulated during the determination of the transmitted power P and the transfer efficiency r while the value of the third parameter is fixed.

According to yet another uncovered embodiment, the three parameters (Fin, Phi and Rin) can be modulated during the determination of the transmitted power P and the transfer efficiency r.

In the claims, the word "comprising" does not exclude other elements or steps, and the use of the indefinite article "a" or "an" does not exclude a plurality.

The mere fact that different features are recited in mutually dependent claims does not indicate that a combination of these features cannot be advantageously used. Finally, any reference used in the claims should not be construed as a limitation of the scope of the invention.

Claims

1. Method for controlling an electrical energy transfer device by induction comprising: o a primary circuit (20) comprising: ■ a phase-shift controlled inverter Phi (22) and providing a voltage injection frequency Fin, the inverter (22) being capable of being connected to a voltage network (2), ■ a primary inductive cell (24) capable of being connected to the terminals of the inverter (22), comprising a first capacitor (26) and a first inductance (28), o a secondary circuit (40) comprising: ■ a voltage rectifier (42) capable of being connected to an electrical energy storage unit (4) and of performing an impedance adaptation R _ref on its alternating input independently of the impedance of the electrical energy storage unit (4), ■ a secondary inductive cell (44) capable of being connected to the terminals of the voltage rectifier (42), comprising a second capacitor (46) and a second inductance (48), the method comprising the following steps: fixing the values of two parameters among Phi, Fin and R _ref , modulating the value of the parameter not having been fixed. 2. Method according to claim 1, in which the parameters whose values are fixed are Fin and R _re f. 3. Method according to claim 2, comprising a step of fixing the value of the voltage injection frequency Fin as being the value of the resonance frequency giving a maximum effective value of the current in the inverter at given Phi and R _ref . 4. Method according to one of claims 2 or 3, comprising a step of fixing the value of R _re f as a function of the values of the capacitance of the second capacitor, of the second inductance and of the coupling rate K of the primary and secondary inductive cells at given Phi and Fin. 5. Method according to claim 1, in which the parameters whose values are fixed are Fin and Phi. 6. Method according to claim 5, comprising a step of fixing the value of the voltage injection frequency Fin as being the value of the resonance frequency giving a maximum effective value of the current in the inverter at given Phi and R _ref . 7. Method according to one of claims 5 or 6, in which the value of Phi is set to a value greater than or equal to 175° and less than or equal to 180°. 8. Method according to claim 1, in which the parameters whose values are fixed are R _ref and Phi. 9. A method according to any preceding claim, wherein the voltage rectifier (42) performing the impedance matching comprises two switching arms in parallel, one of the first and second switching arms switching at the frequency of the contactless exchanged energy, and the other of the first and second arms switching at a frequency equal to or greater than 5 times or 10 times the contactless energy exchange frequency. 10. A method according to claim 9, one of the switching arms switching at the frequency of the energy exchanged without contact with a duty cycle of 50%, and the other switching arm switching at a frequency equal to or greater than 5 times or 10 times that of the energy transmitted from the primary circuit (20) and with a duty cycle modulated according to the measured alternating current and the voltage on the alternating input of the two switching arms. 11. Device for transferring electrical energy by induction (1), comprising a control unit implementing the method according to any one of the preceding claims.