FR3087596A1 - ELECTRICAL SYSTEM AND METHOD FOR CHARGING A BATTERY, ESPECIALLY FOR A VEHICLE - Google Patents

Abstract

The present invention relates to an electrical system, in particular for an electric or hybrid vehicle, comprising an electric charger (OBC), intended to supply a supply battery (HV), intended to provide energy for driving the vehicle, said charger (OBC) comprising a unidirectional rectifier circuit (RED), a link capacitor (Clink), a DC-DC converter circuit, and at least one thyristor (T1, T2) having two operating states: • a state 0, according to which said at least one thyristor (T1, T2) performs an open switch function, • a state 1, according to which said at least one thyristor (T1, T2) behaves like a pass-through diode making it possible to charge the link capacitor (Clink) of the DC-DC converter circuit, the operating state of at least one thyristor (T1, T2) being controlled by a control signal so as to ensure the precharging of the link capacitor (Clink) of the DC-DC converter circuit.

Description

ELECTRICAL SYSTEM AND METHOD FOR CHARGING A BATTERY, ESPECIALLY FOR VEHICLES TECHNICAL FIELD AND SUBJECT OF THE INVENTION

In general, the invention relates to the field of electrical systems intended for recharging a battery, in particular intended to be installed in a motor vehicle, in particular a motor vehicle with an electric or hybrid motor.

[0002] More specifically, an electric or hybrid vehicle comprises a low voltage supply battery, for supplying the electrical equipment of the vehicle, and a high voltage supply battery which participates in the propulsion of the vehicle.

It is known that the vehicle comprises an on-board electric charger, commonly designated by those skilled in the art by the acronym OBC for “On-Board Charger” in English, used for recharging the high voltage supply battery.

STATE OF THE ART

The electric energy recharging of the high voltage supply battery is carried out in a known manner by connecting it, via a high voltage electrical network of the vehicle, in this case an on-board electric charger OBC, to a network 20 of external power supply, for example the household AC power grid.

Referring to Figure 1, there is shown an embodiment of an onboard electric charger OBC10 according to the state of the art, connected between an external power supply network G1 and an HV power supply battery high tension.

[0005] An OBC10 on-board electric charger comprises in known manner a rectifier RED10, a power factor correction circuit PFC10, said power factor correction circuit PFC10 comprising an AC-DC converter circuit, a DC-DC converter DC / DC10 and a PC10 soft start module.

The RED10 rectifier converts an alternating voltage into a pulsed rectified voltage, that is to say a variable voltage but of constant sign.

The power factor corrector circuit PFC10, connected at the output of the rectifier RED10, makes it possible to deliver a positive DC voltage at its output, from a variable voltage, supplied here by the rectifier RED10.

Finally, the DC / DC10 DC / DC converter, connected at the output of the power factor correction circuit PFC10, makes it possible to convert 2 the DC voltage, at the output of said power factor correction circuit PFC10, into another DC voltage, suitable for charge the HV battery pack.

In addition, a link capacitor Chnk is connected in parallel between the output of the power factor corrector circuit PFC10 and the DC / DC converter DC / DC10. 5

Referring to Figure 2, the rectifier RED10 here comprises an assembly of four diodes mounted in a diode bridge.

[0007] The PC10 soft start module makes it possible to prevent a large inrush current from running through the on-board electrical charger OBC10 when the electrical system is switched on.

In other words, when the charging of the HV 10 power supply battery begins, the PC10 soft start module avoids a transient overcurrent that occurs when switching on certain electrical receivers, and therefore avoids an excessively high rise. rapid and significant load, especially in the Chnk binding capacity and therefore a possible deterioration of the Clink binding capacity.

A PC10 progressive start module conventionally comprises two precharge relays 15, here modeled by the switches 110, 111 and a Rio load resistor.

The hi switch is connected bypassing the ho switch and the Rio load resistor, connected in series.

During the starting phase of the on-board electric charger OBC10, in order to charge a supply battery of a vehicle, the switch is first of all open and lio closed and therefore the current passes through the load resistor Rio.

During this phase, the load resistor Rio decreases the input voltage of the on-board electric charger OBC10 and thus prevents an excessive increase in the load, in particular in the connection capacity Chnk.

Then, when the starting phase ends, in other words when there is no longer any risk of transient overcurrent due to starting, the switch 111 closes in order to short-circuit the resistance Rio.

However, this type of PC10 soft start module has drawbacks.

Indeed, first of all, this PC10 soft start module only works for a predetermined period of 1 to 2 seconds.

Furthermore, the relays used in the OBC10 on-board charger have a high cost, which is added to that of the load resistance (s).

As a reminder, in the case of a three-phase OBC10 on-board electric charger, said OBC10 on-board electric charger comprises three load resistors, otherwise it only comprises one.

Thus, the cost in terms of components of such an on-board electric charger OBC10 is very high.

Finally, these components are bulky and use a large surface area on the integrated circuit comprising the on-board electric charger OBC10. 3

To overcome these drawbacks, the present invention proposes to use an on-board electric charger having another type of inexpensive progressive start module and the surface area of which is smaller.

GENERAL PRESENTATION OF THE INVENTION 5

More specifically, the invention relates to an electrical system, in particular for an electric or hybrid vehicle, comprising an electric charger, intended to supply a power supply battery in particular intended to provide energy for driving the vehicle, said charger electrical comprising a unidirectional rectifier circuit, a link capacitor, a DC-DC converter circuit, and at least one thyristor having two operating states: a state 0, according to which said at least one thyristor performs an open switch function / circuit breaker, - a state 1, according to which said at least one thyristor behaves like a pass-through diode making it possible to charge the link capacitor of the DC-DC converter circuit, the operating state of at least one thyristor being controlled by a control signal configured to control said at least one thyristor alternately to state 0 and to state 1 so as to ensure the precharging of d e the connection capacitance of the DC-DC converter circuit.

[0012] The electrical system thus advantageously makes it possible to avoid an overload in the connection capacity and thus to avoid the deterioration of said connection capacity.

In addition, the electrical system according to the invention is a more economical system. 25

Preferably, a starting module controls the charger of the electrical system, said starting module generating a slope signal, said slope signal corresponding to a predefined affine function over a starting time, and said starting module performing the comparison between said slope signal and the absolute input voltage, in other words the absolute value of the input voltage of the charger, and said control signal of said at least one thyristor being a function of said comparison.

Preferably, said control signal of the electrical system: 4 - imposes the operating state of the at least one thyristor at state 1, when the value of the slope signal is greater than the absolute input voltage , - imposes the operating state of at least one thyristor at state 0, when the value of the slope signal is lower than the absolute input voltage. 5

[0016] Thus, the control signal makes it possible to effectively control the operating state of the thyristors.

Advantageously, in a first embodiment, the rectifier circuit of the electrical system comprises two diodes and two thyristors connected in bridge, said thyristors being configured to operate alternately between state 0 and state 1 in order to gradually charge the binding capacity.

Advantageously, the electrical system is economical in terms of area used on the integrated circuit comprising the on-board electric charger.

Advantageously, according to a second embodiment, the rectifier circuit of the electrical system comprises four diodes, said system comprising a thyristor connected between the link capacitor and the terminal of the rectifier circuit to which the anodes of two diodes are connected.

Preferably according to the second embodiment, the rectifier of the electrical system comprises a single thyristor.

Advantageously, according to a third embodiment, the rectifier circuit 20 of the electrical system comprises four diodes, said system comprising a thyristor connected to the terminal of the rectifier circuit to which the cathodes of two diodes are connected.

Preferably, according to the third embodiment, the rectifier of the electrical system comprises a single thyristor. 25

The invention also relates to a method for charging a power supply battery implemented by an electrical system according to one of the preceding claims, comprising the steps of: - generation of a slope signal by the module start-up, - comparison by the start-up module between the slope signal generated previously and the absolute input voltage, 5 - when the value of the slope signal is greater than the absolute input voltage, the at least one thyristor operates according to state 1, if not, the at least one thyristor operates according to state 0, - when the at least one thyristor operates according to state 1, progressive charging of the link capacitor.

Preferably, the method comprises, previously in the step of comparison by the starting module, a step of rectifying the AC input voltage of the system.

The invention also relates to an electric or hybrid motor vehicle 10 comprising an electrical system.

The present invention also relates to an electric or hybrid motor vehicle comprising an electrical system as briefly described above.

DESCRIPTION OF FIGURES 15

The invention will be better understood on reading the description which follows, given only by way of example, and referring to the accompanying drawings given by way of non-limiting examples, in which identical references are given to similar objects and on which: FIG. 1 (already commented on), the functional block diagram of an electrical system according to the state of the art, FIG. 2 (already commented on), the electronic diagram of an electrical system according to the state of the art presented in FIG. 1, FIG. 3 represents the functional block diagram of a first embodiment of an electrical system according to the invention, FIG. 4 represents the electronic diagram of a first embodiment of an electrical system according to the invention shown in figure 3, figure 5 graphically illustrates the embodiment of the embodiment shown in figure 2, figure 6 shows the electronic diagram of a second form of realization n of an electrical system according to the invention, FIG. 7 represents the electronic diagram of a third embodiment of an electrical system according to the invention, 6 - FIG. 8 represents the electronic diagram of a fourth form of embodiment of an electrical system according to the invention, FIG. 9 represents the electronic diagram of a fifth embodiment of an electrical system according to the invention, 5 FIG. 10 represents the electronic diagram of a sixth form for producing an electrical system according to the invention.

It should be noted that the figures show the invention in detail to implement the invention, said figures can of course be used to better define the invention if necessary.

10 DETAILED DESCRIPTION OF THE INVENTION

It is recalled that the present invention is described below using various non-limiting embodiments and is capable of being implemented in variants within the reach of those skilled in the art, also referred to by the present invention. 15

Referring to Figure 3, there is shown a functional block diagram of a first embodiment of an electrical system according to the invention.

This electrical system is in particular intended to be mounted in an electric or hybrid motor vehicle.

In order to charge a high voltage HV power supply battery of a vehicle, an electrical system is used comprising a unidirectional OBC charger.

Said OBC charger is connected between the external power supply source G1 and a high voltage HV power supply battery.

The on-board electric OBC charger comprises in known manner a RED rectifier, a PFC power factor corrector circuit, said PFC power factor corrector circuit comprising an AC-DC converter circuit, a DC-DC converter DC / DC and a PC soft start module.

The rectifier RED, connected to the external power supply source G1, converts an alternating voltage into a pulsed rectified voltage, that is to say a variable voltage but of constant sign.

The PFC power factor correction circuit, connected at the output of the rectifier RED, makes it possible to deliver a positive or negative direct voltage at its output, from a variable voltage, supplied here by the rectifier RED.

Finally, the DC / DC converter, connected between the output of the PFC power factor correction circuit and the HV power supply battery, converts the DC voltage at the output of said PFC power factor correction circuit, into another DC voltage, suitable for charging the HV power supply battery.

In addition, a link capacitor Chnk is connected in parallel between the output of the power factor correction circuit PFC and the DC / DC converter 5 DC / DC.

Still with reference to Figure 3, the PC startup module comprises an ABS rectifier module, a COMP comparison module and a GS slope signal generator.

The ABS rectification module of the PC starter module is connected to the COMP comparison module, which is itself connected to the GS slope signal generator. 10

The PC start-up module is connected to the external power supply source Gl, by the ABS rectifier module, and to the rectifier RED, via the comparison module COMP.

The PC start-up module makes it possible to control the rectifier RED and thus to gradually charge the link capacitor Chnk in order to avoid overcurrent and a deterioration of said link capacitor Clink.

Figure 4 shows an electronic diagram of the electrical system shown in Figure 3, without the PC startup module.

With reference to FIG. 4, the rectifier RED, called a “controlled” rectifier, comprises a mixed Graetz bridge, in other words, an assembly of two diodes D3, D4 and two thyristors T1, T2, connected as a bridge.

This circuit structure is known to those skilled in the art and will therefore not be described in detail here.

According to the first embodiment, the connections between the components of the mixed Graetz bridge are made such that the cathodes of thyristors T1, T2 are connected and such that the anodes of diodes D3, D4 are connected.

Thus, since the cathodes of the two thyristors T1, T2 are connected to the same node, likewise concerning the anodes of the diodes D3, D4, the potential at the level of the cathode of the two thyristors T1, T2, respectively of the anode of the diodes D3, D4, is the same.

RED rectifier is unidirectional, in fact, using a bidirectional rectifier would be unnecessary since diodes D3, D4 and thyristors T1, T2 are unidirectional. 30

Furthermore, the PFC power factor correction circuit also comprises two diodes D5 and D6. 8

The thyristors T1, T2 each comprise, in addition to an anode and a cathode, a third terminal, called a "trigger".

The variation of the gate current makes it possible to control the operation of said thyristors T1, T2.

In fact, in practice, the thyristors T1, T2 controlled have two operating states, a state 0, according to which the thyristors T1, T2 perform an open switch function, and a state 1 according to which the thyristors T1, T2 switch on. behave like a passing diode.

Thus, the operating state of said thyristors T1, T2 also makes it possible to control the voltage and the current in the link capacitor Chsk, in particular when charging an HV power supply battery.

This therefore makes it possible to provide a progressive increase in the voltage at the terminals of the capacitor Chsk, and therefore to avoid overcurrent.

Furthermore, in theory, one could also use any other component having a unidirectional controllable switch function, such as, for example, bipolar transistors with insulated gate, called "IGBTs".

However, these components are expensive: an IGBT transistor generally costs 5 to 15 times more expensive than a diode D3, D4 15 whereas a thyristor is only 50% more expensive than such a diode on average.

Referring to Figure 3, the ABS rectifier module determines the absolute value of the input voltage V, 'alternating and sinusoidal, in order to obtain an absolute input voltage Vabs.

[0045] The slope signal generator GS generates a slope signal, that is to say an affine function, the director coefficient of which is constant and defined over a predefined start-up time SS.

Indeed, this start-up duration SS is defined by the user and it is this duration which defines the duration of precharging of the link capacitor Chnk.

The origin of the slope GS can coincide with a zero crossing of the absolute input voltage Vabs, for example as illustrated in figure 5.

However, this is not a necessary condition.

In fact, the origin of the slope GS can be taken at any value of the absolute input voltage Vabs without this disturbing the precharging of the link capacitor Chsk.

The COMP comparison module is connected to thyristors T1, T2 of the rectifier RED.

It performs the comparison between the generated slope signal and the absolute input voltage Vabs.

This step will be explained in detail during the explanation of the implementation of the electrical system.

Referring to Figure 5, there is shown graphically the method of charging an HV power supply battery, implemented by the first embodiment of the electrical system.

The first graph A represents the variation of the absolute input voltage 9 Vais, and of the affine function fa generated by the slope signal generator GS over a starting time SS.

The second graph B represents the gate current la, and therefore the operating state of thyristors T1, T2.

The third graph C represents the real voltage Vreal at the input of the link capacitor Chnk. 5

Referring to Figures 4 and 5, said method of charging an HV power supply battery firstly comprises a step of rectifying the input voltage Vin.

During this step, the ABS rectifier module of the PC starter module measures the input voltage Via from the external power supply source 01, and determines the value of the absolute input voltage Vabs. 10

Said method then comprises a step of generating a slope signal by the slope signal generator GS, over a preconfigured start time SS, as a function of the desired start time.

Next, the method comprises a step of controlling the gate current 1a of the thyristors T1, T2 by the PC start-up module.

For this, a first comparison step is carried out by the comparison module COMP of the PC start-up module during the start-up period SS.

The comparison module COMP compares the slope signal generated previously and the absolute input voltage Vabs.

If the value of the slope signal is greater than the absolute input voltage Vabs, then a gate current la is sent to the gate of thyristors T1, T2 and the voltage across the terminals of the 20 thyristors T1, T2, between the anode and the cathode, is positive.

However, in the real case, the thyristors T1, T2 do not conduct during the entire period of time when a gate current la is sent to the thyristors T1, T2.

Indeed, when a gate current la is sent, the thyristors T1, T2 become blocking when the value of the real voltage \ ha. ' at the input of the link capacitance Chai, 25 is greater than the input voltage Vs of the system.

The thyristors T1, T2 are controlled at state 1 and therefore behave like pass-through diodes during all the time intervals where the value of the slope signal is greater than the absolute input voltage Vabs. thus allowing the progressive charge of the Chak binding capacity. 30

More specifically, when the thyristors T1, T2 are controlled to state 1, only one thyristor T1 or T2 is conducted and has a current flowing through it.

Indeed, the other thyristor T1 or T2 has a negative voltage at its terminals, and remains blocked.

It is when the input voltage Vin changes polarity that the thyristor T1 or T2 which previously conducted no longer conducts and vice versa.

When the value of the slope signal is less than the absolute input voltage Vabs, the thyristors T1, T2 are controlled to state 0 and behave like an open switch and block the charge of the link capacitor Chnk.

It is thus necessary to wait for the next phase <, descending "of the absolute input voltage Vabs, so that the value of the slope signal becomes again greater than the absolute input voltage Vabs, so that the thyristors T1, T2 become conductive again.

Over the time intervals where the thyristors T1, T2 are on, then the actual voltage Vreal at the input of the Clink link capacitor is equal to the absolute input voltage Vabs.

During these intervals, the Che link capacitor is charged.

Alternately, on the intervals where the thyristors T1, T2 behave like open switches, the link capacitor Chnk does not charge.

[0057] The alternation of the time intervals where the Clink link capacity is charged and the time intervals where the Chnk link capacity does not charge allows the progressive charging of said the Clink link capacity.

The IG gate current control step of the process ends when the Clink link capacitor is loaded, which theoretically corresponds to the instant when the predefined SS start time has elapsed.

From this moment, thyristors T1, T2 20 remain on, and therefore, the real voltage Vreal at the input of the link capacitor Chnk is equal to the absolute input voltage Vabs, itself equal to the absolute value of the input voltage W.

Figures 6, 7 and 8 respectively show a second, third and fourth embodiment of said electrical system, in which the thyristors T1, T2 25 are placed differently in the diode bridge than in the first embodiment.

In the second embodiment, the connections between the components are made so that the cathodes of the diodes D3, D4 are connected and so that the anodes of the thyristors T1, T2 are connected.

According to the third and the fourth embodiment, the connections are made so that the cathode of one of the thyristors T1, T2 is connected to the cathode of one of the diodes D3, D4.

Likewise, the anode of the other thyristor T1, T2 is connected to the anode of the other diode D3, D4. 11

Referring to Figure 9 and Figure 10, there is shown a fifth embodiment, respectively a sixth embodiment, of the electrical system.

According to the fifth and sixth embodiments, the diode bridge is retained, without any diode being replaced by a thyristor.

Indeed, the diode bridge is a common component, and can sometimes be provided in the form of a non-modifiable component block.

In this case, it will not be possible to interchange two of the diodes of the diode bridge with thyristors T1, T2.

Consequently, with reference to FIG. 9, a single thyristor T3 is added between the connection capacitor Oink and the terminal of the rectifier circuit RED to which the anodes of two diodes, here D3 and D4, are connected. 10

Referring to Figure 10, alternatively, the single thyristor T4 is connected between the terminal of the rectifier circuit RED to which the cathodes of two diodes, here D1 and D2, are connected and the input of the corrector circuit of PFC power factor.

As for the first, second, third and fourth embodiments presented above, the fifth and sixth embodiments 15 make it possible to significantly reduce the cost price and the overall volume of the electrical system.

It is specified that the invention is not limited to the examples described and is capable of adaptations within the reach of those skilled in the art.

Claims (9)

CLAIMS 1. Electrical system, in particular for an electric or hybrid motor vehicle, comprising an electric charger (OBC), intended to supply a supply battery (HV) in particular intended to supply energy for driving the vehicle, said electric charger (OBC) comprising a unidirectional rectifier circuit (RED), a link capacitor (Chnk), a DC / DC converter circuit (DC / DC), and at least one thyristor (T1, T2) having two operating states: - a state 0, according to which said at least one thyristor (T1, T2) performs a circuit breaker function, - a state of 1, according to which said at least one thyristor (T1, T2) behaves like a pass diode making it possible to charge the link capacitor (Clink) of the DC-DC converter circuit (DC / DC), the operating state of the at least one thyristor (T1, T2) being controlled by a control signal configured to control said at least one thyristor (T1, T2) alternately at state 0 and at state 1 so as to ensure the precharging of the link capacitor (0,, k) of the DC-DC converter circuit (DC / DC). 2. Electrical system according to the preceding claim, comprising a starting module (PC) for controlling the charger (OBC), said starting module (PC) generating a slope signal, said slope signal corresponding to an affine function (fa). predefined over a start-up time (SS), and said start-up module (PC) performing the comparison between said slope signal and the absolute input voltage (Vabs), in other words the absolute value of the input voltage (Vin ) of the charger (OBC), and said control signal of said at least one thyristor (T1, T2) being a function of said comparison. 3. Electrical system according to the preceding claim, wherein: a. when the value of the slope signal is greater than the absolute input voltage (Vabs), said control signal imposes the operating state of at least one thyristor (T1, T2) at state 1, b. when the value of the slope signal is less than the absolute input voltage (Vabs), said control signal imposes the operating state of the at least one thyristor (T1, T2) at state O. 13 4. System according to one of the preceding claims, wherein the rectifier circuit (RED) comprises two diodes (D3, D4) and two thyristors (T1, T2) connected in bridge, said thyristors (T1, T2) being configured to operate. alternately between state 0 and state 1 in order to progressively charge the connection capacitor 5 (Clink) - 5. System according to one of claims 1 to 3, wherein the rectifier circuit (RED) comprises four diodes (D1, D2, D3, D4), said system comprising a thyristor (T3) connected between the link capacitor (Clink ) and the rectifier circuit terminal (RED) to which the anodes of two diodes (D3 and D4) are connected. 10 6. System according to one of claims 1 to 3, wherein the rectifier circuit (RED) comprises four diodes (D1, D2, D3, D4), said system comprising a thyristor (T4) connected to the terminal of the rectifier circuit ( RED) to which the cathodes of two diodes (D1, D2) are connected. 7. A method of charging a supply battery (HV) implemented by an electrical system according to one of the preceding claims, comprising the steps of: a. generation of a slope signal by the starter module (PC), b. comparison by the starter module (PC) between the slope signal generated previously and the absolute input voltage (Vabs), 20 c. when the value of the slope signal is greater than the absolute input voltage (Vabs), the at least one thyristor (T1, T2) operates according to state 1, otherwise, the at least one thyristor (T1, T2) operates according to state 0, d. when the at least one thyristor (T1, T2) operates according to state 1, progressive charging of the link capacitor (0, nk). 25 8. Method according to the preceding claim, comprising a step of rectifying the AC input voltage (V, n) of the system, previously in the step of comparison by the start-up module (PC). 9. Electric or hybrid motor vehicle comprising an electrical system according to one of claims 1 to 6.