Method for controlling a charger for charging an electrical energy storage unit of a vehicle, and charger

Abstract

The invention relates to a method for controlling a charger (1) for charging an electrical energy storage unit of a vehicle, the charger (1) comprising: - a voltage converter (3; 3a) comprising at least one switching arm (4, 7) comprising two switching cells, these two switching cells (5) being connected in series to the terminals of a first input (12) of the switching arm, an AC voltage being applied directly or indirectly to said first input, these two switching cells being arranged on either side of a center tap (6, 9) defining a second input of the switching arm, - an isolating transformer (20; 20a) comprising a primary winding (21; 21a), one terminal of which is connected to the second input of the switching arm, and a secondary winding (22; 22a), and - an inverter / rectifier (14; 14a), configured to rectify the AC voltage across the terminals of the secondary winding (22; 22a) of the isolating transformer (20; 20a), the method comprising controlling the switching arm (4, 7) of the voltage converter (3; 3a) with a switching frequency that varies depending on the value of the AC voltage associated with the first input (12) of this switching arm (4, 7).

Description

[0001] Description

[0002] Title of the invention: Method for controlling a vehicle electrical energy storage unit charger, and charger

[0003] The present invention relates to a method for controlling a charger for a vehicle electrical energy storage unit, and it also relates to such a charger. The electrical energy storage unit is, for example, a battery, which may have a nominal voltage greater than 60V, for example greater than or equal to 300V, 400V, 800V, or even 1000V.

[0004] The charger includes, in a well-known example:

[0005] - an inverter / rectifier receiving a three-phase alternating voltage as input from a load terminal and providing a direct current voltage as output,

[0006] - one or more capacitors in parallel with the DC output of the inverter / rectifier, and

[0007] - a DC / DC converter located downstream of the inverter / rectifier and connected to the electrical energy storage unit.

[0008] To reduce the number of components, and in particular to avoid the presence of capacitors in parallel with the DC output of the inverter / rectifier or the presence of smoothing inductors for the inverter / rectifier, it is known to group the inverter / rectifier and part of the DC / DC converter within a single voltage converter transforming an alternating voltage at 50 Hz or 60 Hz on its first input into an alternating voltage at another frequency on its other input.

[0009] It is known to switch the switching arm(s) of this single voltage converter at a fixed frequency and to adapt the power transfer to the electrical energy storage unit by adjusting the angular phase shift between the control of this switching arm(s) of the single voltage converter and the control of a separate inverter / rectifier connected to this converter by a transformer. Maintaining a fixed frequency for the control of both the single voltage converter and this other inverter / rectifier results in the concentration of magnetic noise, namely common-mode and differential-mode noise, in a narrow frequency band around this fixed frequency and its harmonics. Due to this concentration of noise in a narrow frequency band, the overall amplitude of this noise can become very high.It is known to vary the switching frequency controlling the single voltage converter and the other inverter / rectifier, but this variation affects the sizing of the voltage converter, particularly its passive components such as inductors and capacitors, and also any transformer present. This variation can also affect power transfer performance and proves complicated to implement in practice.

[0010] There is a need to address the above disadvantages in a simple way.

[0011] The invention aims to address this need and achieves this, in one aspect, by means of a method for controlling a vehicle electrical energy storage unit charger, the charger comprising:

[0012] - a voltage converter comprising at least one switching arm comprising two switching cells, in particular bidirectional in current and voltage, these two switching cells being mounted in series across the terminals of a first input of the switching arm to which an alternating voltage is applied directly or indirectly, these two switching cells being arranged on either side of a midpoint defining a second input of the switching arm,

[0013] - an isolation transformer comprising a primary winding, one terminal of which is connected to the second input of the switching arm, and a secondary winding, and

[0014] - an inverter / rectifier, configured to rectify the alternating voltage across the terminals of the secondary winding of the isolation transformer, the method comprising controlling the switching arm of the voltage converter with a switching frequency varying according to the value of the voltage associated with the first input of this switching arm.

[0015] According to the invention, the variation in the switching frequency of the switching arm depends on the variation in the value of the alternating voltage associated with the first input of this switching arm, this first input receiving, directly or indirectly, an alternating voltage from an electrical network. This alternating voltage is, for example, sinusoidal at 50 Hz or 60 Hz.

[0016] The alternating voltage is associated with the first input of the switching arm in that it is directly or indirectly applied to that first input.

[0017] For example, it is directly applied to the terminals of the first input of the switching arm. In this case, the two switching cells of this switching arm are bidirectional in current and voltage. Each switching cell is then implemented, for example, using a bidirectional current and voltage switch with two control electrodes. Such a switch, known for example as a "Monolithic Bidirectional Switch (MBDS)" or "Four Quadrant Switch," is made using GaN semiconductor technology. Alternatively, each bidirectional current and voltage switching cell is implemented using a combination of controllable electronic switches, for example, by combining two MOSFET transistors in anti-series, or by combining two IGBT transistors in anti-series.

[0018] In another example, the alternating voltage is applied indirectly to the terminals of the first input of the switching arm. This alternating voltage is, for example, applied to the terminals of the first AC input of an inverter / rectifier whose second DC input is directly connected to the first input of the switching arm. This inverter / rectifier thus rectifies the mains voltage, enabling, for example, power factor correction (PFC).

[0019] For the purposes of this application, when a switching arm switches at a given frequency, each of its two switching cells is in the conducting and blocked state in a complementary manner with the same switching frequency.

[0020] The switching frequency applied to the switching arm can be limited within a range of values ​​whose lower limit is reached when the instantaneous value of the alternating voltage is zero, in particular when the instantaneous value of the fundamental of this alternating voltage is zero, and whose upper limit is reached when the instantaneous value of the alternating voltage is equal in absolute value to the amplitude of this alternating voltage, in particular when the instantaneous value of the fundamental of this alternating voltage is equal in absolute value to the amplitude of the fundamental of this alternating voltage.

[0021] The control then assumes the detection of the cancellation of the instantaneous value of the alternating voltage associated with the first input of the switching arm, in particular the detection of the cancellation of the instantaneous value of the fundamental of this alternating voltage.

[0022] This control, which varies the switching frequency within this range to match the instantaneous value of the AC voltage received from the grid, can spread common-mode and differential-mode noise over a wider frequency band. This results in a reduction of the overall associated amplitude without impacting the charger's sizing, and therefore the size of its integrated isolation transformer, and without affecting the charging efficiency of the electrical energy storage unit. The frequency variation within this range is, for example, synchronized with the variation of the instantaneous fundamental value of the AC voltage received from the grid and associated with the first input of the switching arm.

[0023] This order may also offer the following advantages:

[0024] - Avoid saturation of the isolation transformer if a switching frequency that is too low is applied, - Size the isolation transformer for its maximum frequency, so that the space occupied by this transformer is as small as possible.

[0025] - reduce switching losses in switching cells,

[0026] - allow a significant variation in the switching frequency, for example within a range of values ​​whose amplitude can reach several hundred kHz, which can significantly reduce common-mode noise and differential-mode noise,

[0027] - be compatible with AC-side control since other control parameters such as the duty cycles used for switching or the aforementioned angular offset can be controlled to compensate for this frequency variation

[0028] - reduce the size and therefore the cost of the EMC filters used in the charger, given that the associated noises are already reduced due to the aforementioned variation in switching frequency.

[0029] The lower bound of the range of values ​​within which the switching frequency varies can remain fixed or vary.

[0030] The upper limit of the range of values ​​within which the switching frequency varies can remain fixed or vary.

[0031] The switching frequency can vary linearly within the range of values ​​between the upper and lower limits.

[0032] The switching frequency can vary strictly linearly within the range of values ​​between the upper and lower bounds. The switching frequency thus exhibits the shape of a triangular signal as a function of time. Such a signal is therefore composed solely of segments of a broken line with a non-zero slope.

[0033] Applying such a triangular signal ensures that the minimum frequency is present only when the AC voltage crosses zero, and the maximum frequency is present only when the AC voltage reaches its peak. This allows for a reduction in transformer size and prevents saturation. Indeed, with this type of signal, the maximum flux density occurs only during the peak of the AC voltage, and the transformer is sized for the maximum frequency.

[0034] The range of values ​​within which the switching frequency varies can be between 100 kHz and 500 kHz.

[0035] The lower limit of the range of values ​​for the switching frequency is for example between 100 kHz and 300 kHz and / or the upper limit of this range of values ​​is for example between 400 kHz and 600 kHz.

[0036] Throughout the foregoing, the inverter / rectifier may include at least one switching arm, and the duty cycle applied to the converter's switching arm and the duty cycle applied to the inverter / rectifier's switching arm may exhibit a phase shift. Alternatively, the phase shift considered is not between the duty cycle applied to the converter's switching arm and the duty cycle applied to the inverter / rectifier's switching arm, but rather between the electrical angle of the converter's switching arm control and the electrical angle of the inverter / rectifier's switching arm control.

[0037] The converter and inverter / rectifier can thus be controlled using the so-called "phase shift" technique. This phase shift and the respective duty cycles, or electrical angles, can be adjusted according to the variation in the switching frequency, as already mentioned.

[0038] The same switching frequency is applied, for example, to the switching arm(s) of the voltage converter and to the switching arm(s) of the inverter / rectifier.

[0039] Each switching arm of the inverter / rectifier uses, for example, two controllable electronic switches arranged on either side of a midpoint, such as MOSFET or IGBT transistors, so that it does not include bidirectional switching cells in current and voltage. These transistors are, for example, made of GaN or SiC.

[0040] The voltage converter may include a second switching arm arranged in parallel with said switching arm to form a full bridge converter, this second switching arm comprising two switching cells, in particular bidirectional in current and voltage, these two switching cells being mounted in series across the terminals of a first input of the second switching arm to which the alternating voltage is applied directly or indirectly, these two switching cells being arranged on either side of a midpoint defining a second input of the second switching arm, each terminal of the primary winding of the transformer being connected respectively to a midpoint of one of the two switching arms.

[0041] According to one variant, the voltage converter may include a second arm arranged in parallel with said switching arm to form a half-bridge converter, this second arm comprising two capacitors mounted in series across the terminals of a first input of the second arm to which the alternating voltage is applied directly or indirectly, these two capacitors being arranged on either side of a midpoint defining a second input of the second arm, each terminal of the primary winding of the transformer being connected respectively to a midpoint of the switching arm and of the second arm.

[0042] Regardless of whether the voltage converter is half-bridge or full-bridge, the inverter / rectifier rectifying the voltage across the secondary winding of the isolation transformer can have one of the following structures:

[0043] - a structure with two parallel switching arms, each switching arm comprising two controllable electronic switches arranged on either side of a midpoint, and each terminal of the transformer's secondary winding being respectively connected to a respective midpoint,

[0044] - a structure with two switching arms in series on either side of a midpoint connected to one of the terminals of the transformer's secondary winding, the other terminal of this secondary winding being connected between the series arrangement of two capacitors, this series arrangement of capacitors being mounted in parallel with the series arrangement of the two switching arms, each switching arm comprising two electronic switches controllable in series,

[0045] - a structure with two switching arms in series on either side of a first midpoint connected to one of the terminals of the secondary winding of the transformer, the other terminal of this secondary winding being connected between the series arrangement of two capacitors, this series arrangement of capacitors being mounted in parallel with the series arrangement of the two switching arms, and the other terminal of this secondary winding being also connected to each second midpoint of the switching arms, a second midpoint of a switching arm being provided between the two electronic switches controllable in series of this arm.

[0046] The invention also relates, according to another aspect, to a charger for a vehicle's electrical energy storage unit, comprising:

[0047] - a voltage converter comprising at least one switching arm comprising two switching cells, in particular bidirectional in current and voltage, these two switching cells being mounted in series across the terminals of a first input of the switching arm to which an alternating voltage is applied directly or indirectly, these two switching cells being arranged on either side of a midpoint defining a second input of the switching arm,

[0048] - an isolation transformer comprising a primary winding, one terminal of which is connected to the second input of the switching arm, and a secondary winding, and

[0049] - an inverter / rectifier, configured to rectify the alternating voltage at the terminals of the secondary winding of the isolation transformer, and

[0050] - a control unit adapted to execute the steps of the method above. All of the above relating to the method also applies to the loader according to this other aspect of the invention.

[0051] Similar to what has already been mentioned previously, the alternating voltage can be applied directly to the first input of the switching arm, or indirectly to this first input, if necessary, with an inverter / rectifier interposed between this alternating voltage and the first input of the switching arm.

[0052] The control unit can include a microcontroller, or an integrated circuit such as an FPGA or an ASIC. The control unit may consist of a single module or several modules cooperating with each other.

[0053] Throughout the above, the charger may include an AC current filtering stage arranged in series between the connector and the voltage converter. This filtering stage allows, for example, when the AC voltage is polyphase, common-mode current filtering and / or differential-mode current filtering.

[0054] In all of the above, the charger may include a DC current filtering stage arranged in series between the inverter / rectifier and the electrical energy storage unit.

[0055] Throughout the preceding discussion, the mains voltage may have a frequency of 50 Hz or 60 Hz and an RMS value of 230 V or 240 V. The electrical energy storage unit is, for example, a battery, which may have a nominal voltage greater than 60 V, for example, greater than or equal to 300 V, 400 V, 800 V, or even 1000 V. This mains voltage may be the AC voltage under consideration. Alternatively, the AC voltage under consideration corresponds to the electrical signal from the mains after passing through differential-mode filtering inductor(s), for example.

[0056] In all of the above, the charger can charge the electrical energy storage unit with a power of 7kW, 11kW or 22kW, or even more.

[0057] The charger may or may not be housed in the same unit as a DC / DC converter, which performs voltage conversion between the voltage at the terminals of the electrical energy storage unit, known as "high voltage," and the voltage of the vehicle's electrical system, known as "low voltage." As previously mentioned, high voltage is, for example, greater than 60V, or greater than or equal to 300V, 400V, 800V, or even 1000V, while low voltage is, for example, equal to 12V or 48V.

[0058] The charger may include:

[0059] - a second voltage converter comprising at least one switching arm including two switching cells, in particular bidirectional in current and voltage, these two switching cells being connected in series across a first input of the switching arm to which an alternating voltage is applied directly or indirectly, these two switching cells being arranged on either side of a midpoint defining a second input of the switching arm, a second isolation transformer comprising a primary winding, one terminal of which is connected to the second input of the switching arm, and a secondary winding, and a second inverter / rectifier, configured to rectify the alternating voltage across the secondary winding of the second isolation transformer, and

[0060] - a third voltage converter comprising at least one switching arm including two switching cells, in particular bidirectional in current and voltage, these two switching cells being connected in series across a first input of the switching arm to which an alternating voltage is applied directly or indirectly, these two switching cells being arranged on either side of a midpoint defining a second input of the switching arm, a third isolation transformer comprising a primary winding, one terminal of which is connected to the second input of the switching arm, and a secondary winding, and a third inverter / rectifier, configured to rectify the alternating voltage across the secondary winding of the third isolation transformer, each voltage converter having its first input associated with one of the phases of a three-phase voltage, and

[0061] - the control unit commanding, according to the above method, the switching arm of each voltage converter with a switching frequency varying according to the voltage value of the phase associated with the first input of this switching arm of the three-phase alternating voltage, in particular according to the instantaneous voltage value of this phase, in particular according to the instantaneous value of the fundamental voltage of this phase.

[0062] Three frequency signals with a phase shift of 120° can then be used.

[0063] The invention can therefore be applied to electrical energy storage unit loads with a power of 11 kW or 22 kW.

[0064] Throughout all of the above, and regardless of the number of inverters / rectifiers in the charger, at least one isolation transformer, specifically at least one of the isolation transformers or each isolation transformer, may comprise two secondary windings:

[0065] - a first secondary winding corresponding to the aforementioned secondary winding, the voltage of which is rectified by the respective inverter / rectifier to power the electrical energy storage unit, and

[0066] - a second secondary winding forming a low voltage output to an on-board 12V or 48V network for example.

[0067] The presence of these two secondary windings allows the charger to incorporate an additional DC / DC converter function.

[0068] The invention also relates, according to yet another aspect, to a computer program product comprising instructions which lead the above loader to execute the steps of the above method.

[0069] The invention also relates, according to yet another aspect, to a computer-readable medium on which the above-mentioned computer program is stored. For the purposes of this application, the computer capable of reading the computer program is, for example, the aforementioned control unit, possibly via its microcontroller, or its integrated circuit such as an FPGA or an ASIC.

[0070] The invention will be better understood by reading the following description of non-limiting examples of its implementation and by examining the attached drawing in which:

[0071] - [Fig. 1] represents a charger in which an example of a control method according to the invention can be implemented,

[0072] - [Fig.2] is a diagram showing how the switches on the switching arms of the converter and inverter / rectifier of the charger in Figure 1 are controlled,

[0073] - [Fig.3] represents an example of the variation in the switching frequency of the charger in Figure 1 as a function of the evolution of the alternating voltage received from the electrical network,

[0074] - [Fig.4] represents a variant of the charger of figure 1 in which an example of a control method according to the invention can be implemented, this variant differing in the implementation of the converter,

[0075] - [Fig.5] and [Fig.6] represent two variants of the charger of figure 1 in which an example of a control method according to the invention can be implemented, these two variants differing in the implementation of the inverter / rectifier,

[0076] - [Fig.7] and [Fig.8] represent two variants of the charger of Figure 1 in which an example of a control method according to the invention can be implemented, these two variants differing in that: three converters, three transformers and three inverter / rectifiers are mounted in parallel so as to each be respectively assigned to a phase of a three-phase voltage supplied by the electrical network,

[0077] - [Fig.9] represents a variant of the charger of figure 1 in which an example of a control method according to the invention can be implemented, this variant differing in the realization of the transformer which comprises two secondary windings,

[0078] - [Fig. 10] represents a variant of the charger of figure 8 in which an example of a control method according to the invention can be implemented, this variant differing in the realization of one of the three transformers, the latter comprising two secondary windings,

[0079] - [Fig. 11] represents a variant of the charger in Figure 8 in which an example of a control method according to the invention can be implemented, this variant differing in the implementation of two of the three transformers, the latter comprising two secondary windings, and

[0080] - [Fig.12] similarly represents to figure 1 another variant of charger in which an example of control method according to the invention can be implemented.

[0081] Figure 1 shows an example of a charger for a vehicle's electrical energy storage unit connected to an electrical grid. The electrical energy storage unit is a battery used to power an electric vehicle propulsion machine. This battery has, for example, a nominal voltage greater than or equal to 60V, or in particular 300V, 400V, 800V, or even 1000V.

[0082] In the example considered, the electrical network can supply a single-phase voltage with a frequency of 50Hz or 60Hz and an RMS value of 230V or 240V. The single-phase voltage signal is sinusoidal here and is received directly, possibly after passing through a differential mode filter inductor, at a first AC input 12 of a voltage converter 3 which will now be described.

[0083] This voltage converter 3 converts the AC voltage from the mains into an AC voltage of higher frequency, for example an AC voltage with a frequency on the order of a few hundred kHz.

[0084] Converter 3 is implemented in the example shown in Figure 1:

[0085] - a first switching arm 4 comprising two bidirectional switching cells 5 in current and voltage, these two switching cells 5 being mounted in series across the terminals of a first input of the first switching arm 4, these two switching cells 5 being arranged on either side of a midpoint 6 defining a second input of the switching arm, and

[0086] - a second switching arm 7 arranged in parallel with the first switching arm 4, this second switching arm comprising two bidirectional switching cells 5 in current and voltage, these two switching cells 5 being mounted in series across the terminals of a first input of the second switching arm 7, these two switching cells 5 being arranged on either side of a midpoint 9 defining a second input of the second switching arm.

[0087] The voltage converter 3 in Figure 1 is thus a full-bridge converter and its first input 12 can correspond to both the first input of the first switching arm 4 and the first input of the second switching arm 7, while its second input is formed by the union of the second input 6 of the first switching arm 4 and the second input 9 of the second switching arm 7.

[0088] Each switching cell 5 of converter 3 can be obtained using a four-quadrant switch, for example made of GaN. Alternatively, each switching cell 5 is obtained, for example, using a combination of controllable electronic switches, for example by combining two MOSFET transistors in anti-series or by combining two IGBT transistors in anti-series.

[0089] The second input of the voltage converter 3 is here connected to the terminals of the primary winding 21 of an isolation transformer 20. In the present case, one terminal of this primary winding 21 is connected, directly or indirectly, to the midpoint 6 of the first switching arm 4 and the other terminal of this primary winding 21 is connected, directly or indirectly, to the midpoint 9 of the second switching arm 7.

[0090] The isolation transformer 20 further includes a secondary winding 22, namely a single secondary winding 22 in the example of Figure 1. The alternating voltage across this secondary winding 22 is rectified by an inverter / rectifier 14 of the charger 1, an example of which is shown in Figure 1.

[0091] In Figure 1, the inverter / rectifier 14 comprises:

[0092] - two parallel switching arms, namely a first switching arm 15 comprising two controllable electronic switches 16 arranged on either side of a midpoint 17 and a second switching arm 18 comprising two controllable electronic switches 16 arranged on either side of a midpoint 19.

[0093] In this example, one terminal of the secondary winding 22 is connected, directly or indirectly, to the midpoint 17 of the first switching arm 15 and the other terminal of this secondary winding 22 is connected, directly or indirectly, to the midpoint 19 of the second switching arm 18.

[0094] Each controllable electronic switch 18 is for example a GaN or SiC-based Mosfet transistor, or even a Modfet transistor also called HEMT.

[0095] In parallel with the DC output of the inverter / rectifier 14, one or more capacitors 23 can be arranged. The charger also includes a control unit 40 for controlling the various switching cells 5 and the various controllable electronic switches 16 to adapt the load on the electrical energy storage unit to the requirements. This control unit 40 is, for example, implemented using several modules. This control unit 40 includes, for example, microcontrollers and / or integrated circuits.

[0096] In a conventional manner, and as shown in Figure 2 where Vhi denotes the voltage across the primary winding 21 and where Vh2 denotes the voltage across the secondary winding 22, this control consists of acting on the following parameters:

[0097] - value of the electrical angle ai with which the switching cells 5 of the second switching arm 7 of the converter 3 are controlled, the switching cells 5 of the first switching arm 4 of the converter 3 being controlled with an electrical angle of ai -180°, ai being for example equal to 0° when the second switching arm 7 is used as the reference arm,

[0098] - electrical phase shift cp between the control of the second arm 7 of the voltage converter 3 and the control of the first arm 15 of the inverter / rectifier 14, the value of this electrical phase shift determining the power transferred through the isolation transformer 20 and the sign of this electrical phase shift determining whether the power transfer takes place from the primary winding 21 to the secondary winding 22 or in the opposite direction.

[0099] - value of the electrical angle (12 used for the control of the electronic switches 16 of the first switching arm 15 and the electronic switches 16 of the second switching arm 18 of the inverter / rectifier 14, the electronic switches 16 of the first switching arm 15 being here controlled with an electrical angle cp + a-2 and the electronic switches 16 of the second switching arm 18 of the inverter / rectifier 14 being controlled with an electrical angle of cpi2 + (J.2 -180°,

[0100] According to the invention, when the charger 1 is being controlled, the control unit 40 varies the switching frequency applied to the converter 3 according to the value of the voltage on the first input 12 of this converter, as will now be described with reference to Figure 3. The switching frequency of the inverter / rectifier 15 can be controlled to vary in the same way.

[0101] As can be seen in Figure 3, the control unit 40 imposes a switching frequency that varies, in this example, to follow the variations in the instantaneous value of the fundamental of the alternating voltage at the first input 12 of the voltage converter 3. This variation can occur within a bounded range of values, and the switching frequency can reach the lower limit of this range when the instantaneous value of the fundamental of the alternating voltage at the first input 12 is zero. The switching frequency can reach the upper limit of this range when the instantaneous value of the fundamental of the alternating voltage at the first input 12 is equal in absolute value to the amplitude of the fundamental of this alternating voltage.

[0102] The control unit 40 receives, for example, a measurement or an estimate of the instantaneous value of the fundamental of this alternating voltage on the first input 12 of the voltage converter, for example using a phase-locked loop algorithm.

[0103] In the example given, the lower limit of the switching frequency range remains fixed at 200 kHz, as this value is not a limiting factor. Similarly, in the same example, the upper limit of the switching frequency range remains fixed at 500 kHz, as this value is not a limiting factor. This results in a total range of 300 kHz.

[0104] As can be seen in Figure 3, in the example considered, the switching frequency varies strictly linearly within the range of values ​​between the upper and lower limits. The signal showing the evolution of the switching frequency applied by the control unit 40 as a function of time is therefore a triangular signal.

[0105] As already mentioned, this same frequency signal is also used in this example to control the electronic controllable switches 16 of the inverter / rectifier 14. The same frequency signal is therefore used for the voltage converter 3 and the inverter / rectifier 14.

[0106] The invention is not limited to the example just described.

[0107] Other realizations of the voltage converter 3, of the inverter / rectifier 14 are possible, as will now be described with reference to figures 4 to 6, while retaining the control principle with a variable frequency which has just been described.

[0108] Figure 4 differs from Figure 1 in that the voltage converter 3 is a half-bridge converter. The second arm 7 is therefore without switches but includes two capacitors 45 connected in series across the terminals of a first input of the second arm, which is always the first input 12 of the voltage converter 3. These two capacitors 45 are arranged on either side of a midpoint 46 defining a second input of the second arm 7. One terminal of the primary winding 21 of the transformer 20 is connected to the midpoint 6 of the first switching arm 4, and the other terminal of this primary winding 21 is connected to the midpoint 46 of the second arm 7.

[0109] Whether the voltage converter 3 is as shown in Figure 1 or in Figure 4, the inverter / rectifier 14 can have any of the structures shown in Figures 5 or 6, instead of the structure previously described with reference to Figure 1.

[0110] In Figure 5, the two switching arms 15 and 18 are connected in series on either side of a first midpoint 48 connected to one of the terminals of the secondary winding 22 of the transformer 20. The other terminal of this secondary winding 22 is connected between the series arrangement of two capacitors 23, this series arrangement being connected in parallel with the series arrangement of the two switching arms 15 and 18. Each switching arm 15, 18 of the inverter / rectifier 14 also includes two controllable electronic switches 16 connected in series on either side of a second midpoint 50. As can be seen in Figure 5, a capacitor 51 is connected between these two second midpoints 50.

[0111] Figure 6 differs from Figure 5 in that capacitor 51 is not present, and an additional electrical connection via a respective diode is provided between the other terminal of the secondary winding 22 of the transformer and each second midpoint 50 of a switching arm.

[0112] The invention is not limited to the case where a single-phase voltage is present on the first input 12 of the voltage converter 3, as will now be seen with reference to figures 7 and 8.

[0113] The structure described above can, as can be seen from Figures 7 and 8, be tripled to handle a three-phase alternating voltage supplied by the grid. In this case, in addition to the voltage converter 3, the transformer 20, and the inverter / rectifier 14, which in the example of Figures 7 and 8 become the "first voltage converter 3a", "first transformer 20a", and "first inverter / rectifier 14a", the charger 1 can include:

[0114] - a second voltage converter 3b whose structure can be that of voltage converter 3 in Figure 1 or Figure 4,

[0115] - a second isolation transformer 20b, the structure of which can be that of transformer 20 in Figure 1 or Figure 4, and

[0116] - a second inverter / rectifier 14b whose structure can be that of the inverter / rectifier 14 of any of the figures 4 to 6.

[0117] Similarly, charger 1 also includes in the examples of figures 7 and 8: - a third voltage converter 3c whose structure can be that of voltage converter 3 in figure 1 or figure 4,

[0118] - a third isolation transformer 20c, the structure of which can be that of transformer 20 in Figure 1 or Figure 4, and

[0119] - a third inverter / rectifier 14c whose structure can be that of the inverter / rectifier 14 of any of the figures 4 to 6.

[0120] Each cascaded assembly of "voltage converter 3i + isolation transformer 20i + inverter / rectifier 14i" then processes a respective phase of the three-phase voltage from the electrical network. Similar to what was described previously with reference to Figures 1 to 6, the control unit 40, which is here, for example, distributed into several modules, can control the switching cells 5a, 5b, and 5c of each voltage converter 3a, 3b, 3c with a switching frequency varying according to the instantaneous value of the fundamental voltage of the phase of the three-phase AC voltage at the first input of this switching arm.

[0121] We observe:

[0122] - in Figure 7, each voltage converter 3i and each inverter / rectifier 14i comprises, for example, a single switching arm, and

[0123] - on figure 8 that each voltage converter 3i and each inverter / rectifier 14i can alternatively implement two switching arms.

[0124] Other examples to which the present invention applies will now be described, these examples differing from what has just been described by the fact that at least one isolation transformer 20, 20a, 20b, 20c has a second secondary winding 70 in order to benefit from a low voltage output to a 12V or 48V on-board network to add a DC / DC converter functionality to the charger 1.

[0125] According to Figure 9, a second secondary winding 70 is added to the transformer 20, along with an additional inverter / rectifier 71 that rectifies the alternating voltage across this second secondary winding 70 to provide a direct current voltage of, for example, 12V or 48V. This additional inverter / rectifier 71 may, for example, use controllable electronic switches that are GaN- or Si-based transistors.

[0126] According to Figure 10, a second secondary winding 70c is added to the third transformer 20c, along with an additional inverter / rectifier 71c that rectifies the alternating voltage across this second secondary winding 70c to provide a direct current voltage of, for example, 12V or 48V. This additional inverter / rectifier 71c may, for example, use controllable electronic switches such as GaN or Si-based transistors.

[0127] According to Figure 11, we add the following:

[0128] - a second secondary winding 70b on the second transformer 20b and an additional inverter / rectifier 71b rectifying the alternating voltage across this second secondary winding 70b to provide a direct voltage of 12V or 48V for example, and

[0129] - a second secondary winding 70c to the third transformer 20c and an additional inverter / rectifier 71c rectifying the alternating voltage across the terminals of this second secondary winding 70c to provide a direct voltage of 12V or 48V for example.

[0130] Each additional inverter / rectifier 71b or 71c, for example, implements controllable electronic switches that are GaN- or Si-based transistors.

[0131] Figure 12 differs from everything described above in that the first input 12 of the switching arms 4, 7 does not directly receive the alternating voltage. This alternative example shows that an inverter / rectifier 80 is interposed between the first input 12 and the electrical grid. As is known, this inverter / rectifier 80 can rectify the grid voltage at 50 Hz or 60 Hz into a direct current voltage, optionally using two switching arms 81. The rectified voltage is received at the first input 12 of the voltage converter 3. According to this example, it is not necessary for the switches 5 to be bidirectional in both current and voltage.

[0132] Similar to what has been described in relation to Figures 1 to 11, and in particular Figure 3, the control unit 40, when controlling the charger 1, can vary the switching frequency applied to the switching arms 4 and 7 of the converter 3 as a function of the value of the fundamental of the voltage on the AC input of the inverter / rectifier 80.

[0133] The use of an alternating voltage indirectly applied to the input of converter 3, as described with reference to Figure 12, still applies to the chargers described with reference to Figures 4 to 11.

Claims

Demands 1. Method for controlling a charger (1) for a vehicle electrical energy storage unit, the charger (1) comprising: - a voltage converter (3; 3a) comprising at least one switching arm (4, 7) 5 comprising two switching cells (5), in particular bidirectional in current and voltage, these two switching cells (5) being mounted in series across the terminals of a first input (12) of the switching arm to which an alternating voltage is applied directly or indirectly, these two switching cells being arranged on either side of a midpoint (6, 9) defining a second input of the arm of 10 switching, - an isolation transformer (20; 20a) comprising a primary winding (21; 21a) one terminal of which is connected to the second input of the switching arm, and a secondary winding (22; 22a), and - an inverter / rectifier (14; 14a), configured to rectify the alternating voltage to 15 terminals of the secondary winding (22; 22a) of the isolation transformer (20; 20a), the method comprising the control of the switching arm (4, 7) of the voltage converter (3; 3a) with a switching frequency varying according to the value of the alternating voltage associated with the first input (12) of this switching arm (4, 7).

202. A method according to claim 1, wherein the switching frequency applied to the switching arm is limited within a range of values ​​whose lower limit is reached when the instantaneous value of the alternating voltage is zero, in particular when the instantaneous value of the fundamental of this alternating voltage is zero, and whose upper limit is reached when the instantaneous value of the alternating voltage is equal to 25 absolute value to the amplitude of this alternating voltage, in particular when the instantaneous value of the fundamental of this alternating voltage is equal in absolute value to the amplitude of the fundamental of this alternating voltage.

3. A method according to the preceding claim, wherein the switching frequency varies linearly within the range of values ​​between the upper and lower limits. 30 lower.

4. Method according to the preceding claim, wherein the switching frequency varies in a strictly linear manner within the range of values ​​between the upper and lower bounds, such that the signal showing the evolution of the switching frequency as a function of time is a triangular signal.

5. Method according to any one of claims 2 to 4, wherein the amplitude of the range of values ​​in which the switching frequency varies is between 100 kHz and 500 kHz.

6. Method according to any one of claims 2 to 5, wherein the lower bound of the range of values ​​for the switching frequency is between 100 kHz and 300 kHz and / or wherein the upper bound of this range of values ​​is between 400 kHz and 600 kHz.

7. Method according to any one of the preceding claims, wherein the inverter / rectifier (14; 14a) comprises at least one switching arm (15, 18), and wherein the electrical angle applied for the control of the switching arm (4) of the voltage converter (3) and the electrical angle applied for the control of the switching arm (15) of the inverter / rectifier (14) exhibit a phase shift.

8. A method according to any one of the preceding claims, wherein the voltage converter (3) comprises a second switching arm (7) arranged in parallel with said switching arm (4) to form a full-bridge converter, this second switching arm (7) comprising two switching cells (5), in particular bidirectional in current and voltage, these two switching cells (5) being mounted in series across the terminals of a first input (12) of the second switching arm to which the alternating voltage is applied directly or indirectly, these two switching cells (5) being arranged on either side of a midpoint (9) defining a second input of the second switching arm (7), each terminal of the primary winding (21) of the transformer (20) being connected respectively to a midpoint (6, 9) of one of the two switching arms (4, 7).

9. Method according to any one of claims 1 to 7, wherein the voltage converter comprises a second switching arm (7) arranged in parallel with said switching arm to form a half-bridge converter, this second arm comprising two capacitors (45) mounted in series across a first input of the second arm to which the alternating voltage is applied directly or indirectly, these two capacitors being arranged on either side of a midpoint (46) defining a second input of the second arm (7), each terminal of the primary winding (21) of the transformer (20) being connected respectively to a midpoint of the switching arm (6, 46) and of the second arm.

10. A method according to any one of the preceding claims, wherein the alternating voltage is directly applied to the terminals of the first input (12) of the arm of switching (4, 7) and wherein the two switching cells (5) of said arm are bidirectional in current and voltage.

11. Method according to any one of claims 1 to 9, wherein the alternating voltage is applied across the terminals of a first alternating input of an inverter / rectifier (80) whose second direct input is directly connected to the first input (12) of the switching arm (4, 7).

12. Charger (1) for vehicle electrical energy storage unit, comprising: - a voltage converter (3; 3a) comprising at least one switching arm (4, 7) comprising two switching cells (5), in particular bidirectional in current and voltage, these two switching cells (5) being connected in series across the terminals of a first input (12) of the switching arm to which an alternating voltage is applied directly or indirectly, these two switching cells being arranged on either side of a midpoint (6, 9) defining a second input of the switching arm, - an isolation transformer (20; 20a) comprising a primary winding (21; 21a) one terminal of which is connected to the second input of the switching arm, and a secondary winding (22; 22a), and - an inverter / rectifier (14; 14a), configured to rectify the alternating voltage across the terminals of the secondary winding (22; 22a) of the isolation transformer (20; 20a), and - a control unit (40) adapted to carry out the steps of the method according to any one of the preceding claims.

13. Charger according to the preceding claim, the alternating voltage being directly applied to the first input (12) of the switching arm (4, 7) 14. Charger according to claim 12 or 13, comprising: - a second voltage converter (3b) comprising at least one switching arm including two switching cells, in particular bidirectional in current and voltage, these two switching cells being mounted in series across the terminals of a first input of the switching arm to which an alternating voltage is applied directly or indirectly, these two switching cells being arranged on either side of a midpoint defining a second input of the switching arm, a second isolation transformer (20b) comprising a primary winding, one terminal of which is connected to the second input of the switching arm, and a secondary winding, and a second inverter / rectifier (14b), configured to rectify the alternating voltage across the terminals of the secondary winding of the second isolation transformer (20b), - a third voltage converter (3c) comprising at least one switching arm comprising two switching cells, in particular bidirectional in current and voltage, these two switching cells being connected in series across the terminals of a first input of the switching arm to which a voltage is applied directly or indirectly 5 alternating voltage, these two switching cells being arranged on either side of a midpoint defining a second input of the switching arm, a third isolation transformer (20c) comprising a primary winding, one terminal of which is connected to the second input of the switching arm, and a secondary winding, and a third inverter / rectifier (14c), configured to rectify the alternating voltage to 10 terminals of the secondary winding of the third isolation transformer (20c), each voltage converter (3a, 3b, 3c) having its first input associated with a phase of a three-phase voltage, and - the control unit (40) being adapted to perform the steps of the method according to any one of claims 1 to 10 to control the switching arm of each 15 voltage converter (3a, 3b, 3c) with a switching frequency varying according to the voltage value of the phase associated with the first input of this switching arm of the three-phase alternating voltage, in particular according to the instantaneous voltage value of this phase, in particular according to the instantaneous value of the fundamental voltage of this phase. 2015. Product computer program comprising instructions which lead the loader (1) according to any one of claims 12 to 14 to execute the steps of the method according to any one of claims 1 to 11.

16. Computer-readable medium on which the computer program according to claim 15 is recorded. 25

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