Converter control device, vehicle and associated control method

Abstract

The invention relates to a converter control device for delivering an alternating voltage with a predetermined period, the control device being configured to: at the end of each half-period: calculate an RMS value of the current that has flowed through the converter; determine a voltage setpoint equal to: a regulated voltage setpoint (22) depending on the calculated RMS value of the current and a limiting RMS current, if the calculated RMS value of the current is greater than or equal to the limiting RMS current; and a predetermined nominal voltage setpoint (20) otherwise; control the converter to deliver a voltage conforming to the determined voltage setpoint; and during an overcurrent, control the converter to deliver a voltage conforming to a corrected voltage setpoint (24), obtained by clipping the voltage setpoint according to a saturation amplitude (Vsat). Figure 2 for the abstract.

Description

Title of the invention: Converter control device, vehicle and associated control method technical field

[0001] The present invention relates to a control device configured to control a converter in order to deliver, in a V2L mode of power transfer from a battery to a load via the converter, an alternating voltage having a predetermined period.

[0002] The invention also relates to a vehicle comprising such a control device, a control method and a computer program for implementing such a control method.

[0003] The invention applies to the field of electric vehicles, and more specifically to electric vehicles capable of supplying electrical power to an external load. State of the art

[0004] In the field of electric vehicles, particularly electric automobiles, it is known to use a converter to transfer electrical power between a vehicle battery (configured to operate at a direct current voltage) and an external circuit, such as an alternating current network or a load.

[0005] Such a converter generally includes switching elements, such as transistors, and is associated with a control device generally configured to control the converter in order to control the shape of the current flowing in the converter.

[0006] For example, in a so-called "charging" mode, in which power from an alternative network is used to recharge the vehicle's battery, the converter is controlled to achieve a power factor deemed satisfactory for recharging the battery.

[0007] Furthermore, in a so-called "V2L" (Vehicle-to-Load) operating mode, in which electrical power is transferred from the on-board battery to a load connected to the converter, the converter is controlled to convert the direct current voltage available at the terminals of the on-board battery into an alternating current voltage that will power the external load. In this V2L mode, the current flowing through the converter is not controlled, as it depends on the load.

[0008] Such a converter is designed to operate up to a predetermined maximum current. Therefore, it is necessary to limit the current flowing from the battery on board towards external charging, so as to maintain its value below the predetermined maximum current, thus avoiding damage to the converter.

[0009] For example, it is known to control the converter so as to apply saturation to the alternating voltage generated at its output, whenever the value of the delivered current reaches a predetermined limit.

[0010] However, such a control method does not give complete satisfaction.

[0011] Indeed, such saturation results in a clipped, therefore non-sinusoidal, output voltage, which significantly degrades the harmonic distortion rate at the converter output.

[0012] Furthermore, if the load is not purely resistive, the current drawn by said load may continue to increase due to transient phenomena, even in the event of saturation. Therefore, damage to the converter remains possible.

[0013] One object of the present invention is to remedy at least one of the drawbacks of the prior art.

[0014] Another object of the invention is to provide a control device for a converter which, in V2L mode, limits the degradation of the harmonic distortion rate when the current absorbed by the load reaches or exceeds the predetermined maximum current.

[0015] Another object of the invention is to provide a control device for a converter which, in V2L mode, limits the converter's exposure to overcurrents. Description of the invention

[0016] To this end, the invention relates to a control device of the aforementioned type, further configured to, in V2L mode: • at the end of each half-period: • calculate an effective value of a current that has flowed through the converter during the elapsed half-period; • determine, for the following half-period, a voltage setpoint: • equal to a regulated voltage setpoint dependent on the calculated RMS value of the current and a limiting RMS current, if the calculated RMS value of the current is greater than or equal to the limiting RMS current; and • equal to a predetermined nominal voltage setpoint otherwise; • control the converter to deliver, during the following half-period, a voltage respecting the set voltage of- finished; and • when an overcurrent occurs, corresponding to a situation in which an instantaneous value of the current flowing through the converter becomes greater than or equal to a predetermined limit instantaneous current, command the converter to deliver, during the current half-period, a voltage respecting a corrected voltage setpoint, obtained by clipping the voltage setpoint according to a saturation amplitude equal to the value of said voltage setpoint at the time of the overcurrent.

[0017] Indeed, such a control device exploits the fact that the effect of current saturation is immediate, while the beneficial effects of control based on the effective value of the current tend to manifest themselves less quickly.

[0018] This results in a control law which allows a rapid limitation of overcurrents, so as to immediately protect the converter in case of overcurrent, and which progressively implements a control based on the effective value of the current, which has the effect of limiting high harmonics and resulting in a satisfactory harmonic distortion rate.

[0019] In addition, thanks to such a control device, the effective current is controlled, so that the risks of excessive heating (and therefore damage) of the converter are reduced.

[0020] The device according to the invention can be any type of device such as a server, a computer, a tablet, a calculator, a processor, a computer chip, programmed to implement the process as defined below, for example by executing the computer program as defined below.

[0021] Advantageously, the control device according to the invention has one or more of the following characteristics, taken individually or in any technically feasible combination:

[0022] the control device is configured to calculate the RMS value of the current, to determine the regulated voltage setpoint and to reset the saturation voltage at each crossing of 0 of the voltage delivered by the converter;

[0023] The control device is configured to calculate the regulated voltage setpoint as a result of the product of: • a sinusoidal function of unit amplitude; • an effective factor depending on the calculated effective current value and the limiting effective current; • a predetermined nominal amplitude;

[0024] The control device is configured to: • Calculate an error factor equal to: leffjirn bff leff.lim • where leffjim is the limiting effective current, and • leff is the calculated effective value of the current; • implement a regulator to determine a correction factor from the error factor; calculate the effective factor as being equal to the result of the sum of 1 and the determined correction factor, restricted to the interval [0 ; 1];

[0025] the control device is configured to calculate, for each half-period, an overall factor equal to the product between the effective factor and a saturation factor, defined as the result of dividing the saturation amplitude by the regulated amplitude, the control device being, furthermore, configured to allow the operation of the converter in V2L mode according to the calculated overall factor;

[0026] the control device is configured to control the shutdown of the converter if the value of the overall factor is less than a predetermined threshold;

[0027] The control device is configured to, at the end of each half-period, calculate an RMS value of the voltage delivered by the converter during said half-period, the limiting RMS current being equal to the smaller of the following values: • on the one hand, a result of dividing a specified maximum apparent power for the converter by the calculated RMS voltage; and • on the other hand, a maximum effective current specified for the converter.

[0028] According to another aspect of the invention, a vehicle is proposed comprising a converter, a battery connected to terminals of the converter, and a control device as defined above connected to the converter to control the operation of said converter.

[0029] According to another aspect of the invention, a method is proposed for controlling a converter to deliver, in a V2L mode of power transfer from a battery to a load via the converter, an alternating voltage having a predetermined period, the control method comprising, in the V2L mode, the steps: • at the end of each half-period: • calculation of an effective value of a current that has flowed through the converter during the elapsed half-period; • Determination of a voltage setpoint for the following half-period: • equal to a regulated voltage setpoint dependent on the calculated RMS value of the current and an effective current limit, if the calculated RMS value of the current is greater than or equal to the limit RMS current; and • equal to a predetermined nominal voltage setpoint otherwise; • control of the converter to deliver, during the following half-period, a voltage respecting the determined voltage setpoint; and • when an overcurrent occurs, corresponding to a situation in which an instantaneous value of the current flowing through the converter becomes greater than or equal to a predetermined limit instantaneous current, commands the converter to deliver, during the current half-period, a voltage respecting a corrected voltage setpoint, obtained by clipping the voltage setpoint according to a saturation amplitude equal to the value of said voltage setpoint at the time of the overcurrent.

[0030] According to another aspect of the invention, a computer program is proposed comprising executable instructions which, when executed by computer, implement the steps of the process as defined above.

[0031] The computer program can be in any computer language, such as for example in machine language, in C, C++, JAVA, Python, etc. Brief description of the figures

[0032] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0033] Figure [Fig.1] is a schematic representation of an electric vehicle comprising a control device according to the invention;

[0034] Figure [Fig.2] is a graph representing the evolution of a nominal voltage setpoint, a regulated voltage setpoint, and a corrected voltage setpoint as a function of time; and

[0035] Figure [Fig.3] is a diagram illustrating a calculation of the voltage setpoint regulated by the control device of Figure [Fig.1].

[0036] It is understood that the embodiments described below are in no way limiting. In particular, variants of the invention may be conceived comprising only a selection of the features described below, isolated from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art. This selection includes at least one preferably functional feature without structural details, or with only a portion of the structural details if this part is only sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0037] In particular, all the variants and all the embodiments described are combinable with each other if nothing prevents this combination from a technical point of view.

[0038] In the figures and in the rest of the description, elements common to several figures retain the same reference. Detailed description

[0039] A vehicle 2 according to the invention is illustrated in Figure [Fig. 1]. Vehicle 2 is an electric vehicle, or a hybrid vehicle. For example, vehicle 2 is an automobile.

[0040] The vehicle 2 carries a battery 4, a converter 6 and a control device 8.

[0041] The battery 4 is configured to store electrical energy, and is connected to the first terminals 10 of the converter 6.

[0042] In a known manner, the converter 6 is adapted to transfer electrical energy between the battery 4 and an electrical network or a load 12 connected to second terminals 14 of the converter 6.

[0043] In addition, the control device 8 is connected to the converter 6 to control the operation of the converter 6.

[0044] Preferably, the control device 8 is configured to control the converter 6 so that it operates in a so-called "V2L" (Vehicle To Load) mode. In such a V2L mode, the converter 6 transfers electrical power from the battery 4 to the load 12.

[0045] More specifically, in V2L mode, the converter 6 provides the load 12 with an alternating voltage having a predetermined period.

[0046] For example, in France, such a period is 20 ms (milliseconds), which corresponds to a frequency of 50 Hz (hertz). Preferably, in France, under normal operating conditions, such an alternating voltage has an RMS value of 230 V (volts), i.e., an amplitude of 324 V.

[0047] To control the characteristics of the voltage applied between the second terminals 14 of the converter 6, the control device 8 is, in particular, configured to implement pulse-width modulation (or PWM, from the English "Pulse-Width Modulation").

[0048] In particular, the control device 8 is configured to, at the end of each half-period of the alternating voltage, in particular at each zero crossing of the voltage delivered by the converter 6, calculate an effective value Ieff of a current circulating through converter 6 during said half-period elapsed.

[0049] First case: Ieff < Ieffjim

[0050] If the calculated effective value Ieff of the current is less than a limit effective current Ieff,lin» The control device 8 is configured to control the converter 6 so as to deliver a voltage respecting a voltage setpoint equal to a nominal voltage setpoint 20 (figure [Fig.2]), having a predetermined amplitude called “nominal amplitude VN”.

[0051] By "nominal voltage setpoint", it is understood, for the purposes of the present invention, to be a time signal, preferably sinusoidal, whose amplitude is equal to the nominal amplitude VN.

[0052] For example, the limiting effective current Ieff>lim is predetermined. Alternatively, the limiting effective current Ieffjim is determined at the end of each half-period.

[0053] In this case, the control device 8 is configured to, at the end of each half-period, in particular at each crossing of 0 of the voltage delivered by the converter 6, calculate an effective value Veff (called "effective voltage Veff") of said voltage delivered by the converter 6 during said half-period elapsed.

[0054] Furthermore, in this case, the limiting effective current Ieff>iim is equal to the smaller of the following values: • on the one hand, a result of dividing a maximum apparent power specified for converter 6 by the calculated effective voltage Veff; and • On the other hand, a maximum effective current is specified for converter 6.

[0055] Such a calculation is advantageous, insofar as it leads to a less drastic reduction in the amplitude of the generated voltage, within the framework of the control that will now be described, if power is the limiting factor. This characteristic therefore makes it possible to take into account two different limitations (power and current) which are not necessarily correlated since they depend on the voltage, which is variable.

[0056] Second case: Ieff > Ieffjim

[0057] In addition, if the calculated effective value Ieff of the current is greater than or equal to the limit effective current Ieffjim, the control device 8 is configured to determine, for the next half period, a voltage setpoint equal to a regulated voltage setpoint 22 (figure [Fig.2]) depending on the calculated effective value Ieff of the current and the limit effective current Ieffjim.

[0058] By "regulated voltage setpoint", it is understood, in the context of the present invention, to be a time signal, preferably sinusoidal, having an amplitude (called "regulated amplitude VR") depending on the calculated effective value Ieff and the limiting effective current Ieffj;m.

[0059] As illustrated by figure [Fig.2], such a regulated voltage setpoint 22 generally exhibits a smaller amplitude compared to the nominal voltage setpoint 20.

[0060] A preferred method of calculating the regulated voltage setpoint 22 is illustrated by figure [Fig.3].

[0061] To calculate the regulated voltage setpoint 22, the control device 8 is preferably configured to calculate an effective factor aeff. Such an effective factor aeff is a function of the calculated effective current value Ieff and the limiting effective current Ieffjim*

[0062] For example, to determine the effective factor aeff, the control device 8 is configured to first calculate an error factor aeir satisfying: " _Lff.lim " Fff ^err- j Mï.hm

[0063] In this case, the control device 8 is also configured to determine a correction factor acor from the error factor aeiT, for example by implementing a controller 24, such as an integral controller.

[0064] Furthermore, in this case, and as shown in Figure [Fig. 3], the control device 8 is configured to calculate the aforementioned effective factor aeff as being equal to the sum of 1 and the previously determined correction factor acor, restricted to the interval [0; 1]. In other words: • if the result of said sum is strictly greater than 1, then the effective factor aeff is taken to be equal to 1; and • if the result of said sum is strictly less than 0, then the effective factor aeff is taken to be equal to 0.

[0065] Furthermore, the control device 8 is configured to calculate the regulated voltage setpoint 22 as the product of: • a sinusoidal function of unit amplitude; • the effective factor aeff; and • the predetermined nominal amplitude VN.

[0066] In other words, the regulated amplitude VR of the regulated voltage setpoint 22 is equal to the product aeffVN.

[0067] Restricting the effective factor aeff to the interval [0; 1] has the advantageous effect of leading to a regulated amplitude VR which is significantly reduced compared to the predetermined nominal amplitude VN.

[0068] The control device 8 is further configured to control the converter 6 in order to deliver, during the following half-period, a voltage respecting the determined regulated voltage setpoint 22.

[0069] Such a control leads to a decrease, over time, in the effective value of the current, until it reaches a value equal to the limiting effective current Ieff,iim- This results in an increase in the regulated amplitude VR, until a situation is reached where the voltage setpoint amplitude is the nominal amplitude VN.

[0070] Third case: Iinst > Imax

[0071] Furthermore, at any time, when an overcurrent occurs, i.e. when an instantaneous value Iinst of the current flowing through the converter 6 becomes greater than or equal to a predetermined instantaneous limit current Imax, the control device 8 is configured to control the converter 6 so that it delivers a voltage respecting a corrected voltage setpoint 24.

[0072] Such a corrected voltage setpoint 24 is obtained by clipping the current voltage setpoint (the voltage setpoint being equal either to the nominal voltage setpoint 20 or to the regulated voltage setpoint 22 for the current half-period, depending on the calculated RMS value Ieff) according to a saturation amplitude Vsat*

[0073] The saturation amplitude Vsat is equal to the value of the voltage setpoint at the time of the overcurrent.

[0074] In other words, the control device 8 is configured to control the converter 6 so that the output voltage is included, for the current half-period, in the range [-Vsat ; Vsat].

[0075] Preferably, to ensure operation of the control device 8 which protects the converter 6, the limiting effective current Lffjim and the limiting instantaneous current Imax satisfy the following relationship: 1^ Imax efflim —

[0076] Preferably, the control device 8 is configured to reset the saturation voltage Vsat at each zero crossing of the voltage delivered by the converter 6, i.e., at the end of each half-period. As a result, in the absence of overcurrent during the following half-period, the control device 8 will command the converter 6 to deliver a voltage that complies with the voltage setpoint for said following half-period, and not a corrected voltage setpoint.

[0077] Preferably, the control device 8 is also configured to calculate, at each half-period, an overall factor R, equal to the product between the effective factor aeff and a saturation factor asat, defined as the result of dividing the saturation amplitude Vsat, for the current half-period, by the regulated amplitude VR: v et =—— .sat VR

[0078] The overall factor can also be expressed as: Ri——

[0079] In this formula: • AVeff is the difference between the nominal amplitude VN and the regulated amplitude VR; and • AVsat is the difference between the regulated amplitude VR and the saturation amplitude Vsat

[0080] By definition, the overall factor R is less than or equal to 1.

[0081] In addition, the control device 8, in this case, is configured to allow the converter to operate in V2L mode according to the calculated global factor.

[0082] More specifically, the control device 8 is configured to shut down the converter 6 if the value of the overall factor R is less than a predetermined threshold Rmin. This reflects a situation in which, despite the clipping described above and / or a regulated amplitude lower than the nominal amplitude and / or the control provided by the control device 8 does not guarantee a sufficient reduction in the current flowing through the converter 6 to prevent its degradation. In other words, a value of the overall factor R that is too low indicates that the load demands more power than the converter can deliver.

[0083] Furthermore, in the absence of such regulation of the overall factor R, an overall factor R lower than the predetermined threshold Rmin would lead to delivering too low a voltage to an external equipment designed to operate at a voltage with an amplitude equal to the nominal amplitude VN.

[0084] Of course, the invention is not limited to the examples just described.

Claims

Claims

1. Control device (8) configured to control a converter (6) in order to deliver, in a V2L mode of power transfer from a battery (4) to a load (12) via the converter (6), an alternating voltage having a predetermined period, the control device (8) being characterized in that it is, in addition, configured to, in the V2L mode: at the end of each half-period: • calculate an effective value (Ieff) of a current having circulated through the converter (6) during the elapsed half-period; • determine, for the following half-period, a voltage setpoint: • equal to a regulated voltage setpoint (22) depending on the calculated effective value (Ieff) of the current and a limit effective current (I effjim), if the calculated effective value (Ieff) of the current is greater than or equal to the limit effective current (leffjim); and • equal to a predetermined nominal voltage setting (20) otherwise; • control the converter (6) to deliver, during the following half-period, a voltage respecting the determined voltage setpoint (20, 22); and when an overcurrent occurs, corresponding to a situation in which an instantaneous value of the current flowing through the converter (6) becomes greater than or equal to a predetermined instantaneous limit current (Imax), controlling the converter (6) to deliver, during the current half-period, a voltage respecting a corrected voltage setpoint (24), obtained by clipping the voltage setpoint (20, 22) as a function of a saturation amplitude (Vsat) equal to the value of said voltage setpoint (20, 22) at the time of the overcurrent.

2. Control device (8) according to claim 1, configured to calculate the effective value (Ieff) of the current, to determine the regulated voltage setpoint (22) and to reset the saturation voltage (Vsat) each time the voltage delivered by the converter (6) passes through 0.

3. Control device (8) according to claim 1 or 2, configured to calculate the regulated voltage setpoint (22) as being a result of the product of: • a sinusoidal function of unit amplitude; • an effective factor (aeff) depending on the effective value (Ieff) of the calculated current and the effective limit current (Ieff,iim); • a predetermined nominal amplitude (VN).

4. Control device (8) according to claim 3, configured to: • calculate an error factor (aeir) equal to: leffjitu where Ieff,iim is the effective limit current, and Ieff is the effective value of the calculated current; • implement a regulator (24) to determine a correction factor (acor) from the error factor (aeiT); • calculate the effective factor (aeff) as being equal to the result of the sum of 1 and the determined correction factor (acoir), restricted to the interval [0; 1].

5. Control device (8) according to claim 4, configured to calculate, for each half-period, a global factor equal to the product between the effective factor (aeff) and a saturation factor (asat), defined as the result of the division of the saturation amplitude (Vsat) by the regulated amplitude (VR), the control device (8) being, in addition, configured to authorize the operation of the converter in the V2L mode according to the calculated global factor.

6. Control device (8) according to claim 5, configured to control the stopping of the operation of the converter if the value of the global factor is lower than a predetermined threshold.

7. Control device according to any one of claims 1 to 6, configured to, at the end of each half-period, calculate an effective value of the voltage delivered by the converter (6) during said elapsed half-period, the limit effective current (Ieffjim) being equal to the smallest value between: • on the one hand, a result of the division of a maximum apparent power specified for the converter (6) by the calculated effective voltage; and • on the other hand, a maximum effective current specified for the converter (6).

8. Vehicle (2) comprising a converter (6), a battery (4) connected to terminals (10) of the converter, and a control device (8) according to any one of claims 1 to 7 connected to the converter (6) for controlling an operation of said converter (6).

9. Method for controlling a converter (6) to deliver, in a V2L mode of power transfer from a battery (4) to a load (12) via the converter (6), an alternating voltage having a predetermined period, the control method (8) comprising, in the V2L mode, the steps: • at the end of each half-period: • calculation of an effective value (Ieff) of a current having circulated through the converter (6) during the elapsed half-period; • determination, for the following half-period, of a voltage setpoint: • equal to a regulated voltage setpoint (22) depending on the calculated effective value (Ieff) of the current and a limit effective current (I effjim), if the calculated effective value (Ieff) of the current is greater than or equal to the limit effective current (leffjim); and • equal to a predetermined nominal voltage setpoint (20) otherwise;• control of the converter (6) to deliver, during the following half-period, a voltage respecting the voltage setpoint (20, 22);

10. finished; and • when an overcurrent occurs, corresponding to a situation in which an instantaneous value of the current flowing through the converter (6) becomes greater than or equal to a predetermined instantaneous limit current (Imax), control of the converter (6) to deliver, during the current half-period, a voltage respecting a corrected voltage setpoint (24), obtained by clipping the voltage setpoint (20, 22) as a function of a saturation amplitude (Vsat) equal to the value of said voltage setpoint (20, 22) at the time of the overcurrent. A computer program comprising executable instructions which, when executed by a computer, implement the steps of the method according to claim 9.

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