FR2989531A1 - On-board battery charger for charging battery of car, has voltage booster stage including transformer having primary and secondary windings, and switching unit connected in parallel with portion of primary winding - Google Patents

Abstract

The charger has an input stage (ETE) to be connected to a power supply network (RES). A step-down voltage stage (AB) is connected to the input stage, and includes a current coil (L1) for storing electrical energy. An output stage (ETS) is connected to a voltage booster stage (EL1), where the voltage booster stage includes a transformer (TX1) having a primary winding (PR) and a secondary winding (SE), and a switching unit (Q1) connected in parallel with a portion of the primary winding and having only a single switching component. An independent claim is also included for a method for controlling the on-board charger for charging a battery of a car from a power supply network.

Description

The invention relates to battery chargers for a motor vehicle and more particularly to battery chargers embedded in motor vehicles. The realization of an on-board battery charger is subject to constraints of cost, weight, volume and efficiency. To meet these constraints, it is known to those skilled in the art to use in the charger step-down or boost converter circuits to provide a continuous intensity to the vehicle battery. Examples of such circuits are described in US2010 / 165669 and US2009 / 0290384. US2010 / 165669 discloses an isolated lift circuit which utilizes a transformer, a transistor, an inductor, a diode and a capacitance. Document US2009 / 0290384 discloses an isolated step-down circuit which uses a storage capacitor, a complete bridge, a transformer, a rectifier stage with two output voltages. However, in general, the battery voltage varies during charging, so the charger must be able to adapt to a range of voltages. Thus, the battery voltage is lower than the peak voltage of the supply network at the start of charging, which requires that the battery charger be able to operate as a step-down. On the other hand, at the end of charging, the voltage of the battery is greater than the peak voltage of the supply network, which requires that the battery charger can also function as a voltage booster. In the case of a continuous supply network, the peak supply voltage is replaced by the DC supply voltage. The reasoning remains the same.

Thus, a disadvantage of the topology of document US2010 / 165669 is that it does not use a step-down stage to limit a possible inrush current or withstand overvoltages on the input network.

Likewise, the topology of document US2009 / 0290384 does not use a step-up stage to increase the voltage in the case where the output voltage is greater than the input voltage. Another disadvantage is the relative complexity of the secondary winding of the transformer with four windings. It therefore appears that there is a need for a battery charger combining step-down and step-up functions. It is described in the state of the art combinations of the step-down and voltage booster functions. However, they have at least one of the disadvantages below: - they do not have an isolation transformer between the input and the output of the charger. This then results in an increased risk of occurrence of leakage currents combined with a difficulty and a cost of compensation of these increased currents to secure the charger; - they do not have sufficient energy efficiency; or - they have a large number of components. Thus, for example, WO2007 / 078158 discloses a battery charger including voltage raising and lowering functions using an isolation transformer.

This charger does not allow sufficient energy efficiency, particularly because of the use of the transformer as an inductor for storing energy. An object of the invention is therefore to provide a battery charger combining step down and voltage booster functions and which aims to avoid the problems mentioned above. The invention therefore relates to an on-board charger in a motor vehicle for charging a vehicle battery from a power supply network comprising: - an input stage intended to be connected to said power supply network; a voltage step-down stage connected to the input stage and comprising means for storing electrical energy; - a voltage booster stage; and an output stage connected to the step-up stage; According to a general characteristic, the step-up stage comprises: a transformer provided with a primary winding and a secondary winding; and a first switching means connected in parallel to at least a portion of the primary winding and comprising only a single switching component. Thus, we obtain a topology that allows a good energy efficiency, which includes an isolation transformer and the number of switching components of the step stage is reduced. According to one characteristic, the step-up stage comprises a second switching means connected between a primary terminal of the primary winding of the transformer and an input terminal of the step-down stage.

Thus, it is possible to control the demagnetization of the transformer. According to another characteristic, the step-down stage comprises a coil and a third switching means connected in series with a first input terminal of the step-down stage and a diode having an anode connected to a second input terminal of the step-down stage. step-down stage and a cathode connected between said coil and the third switching means. So the inductance of the step-down stage is used instead of the transformer as the inductance for storing energy. This improves energy efficiency. According to a further characteristic, the input stage comprises an input filtering stage intended to be connected to the supply network and a rectifying stage connected to the voltage step-down stage, said rectifying stage comprising a bridge bridge. diode which comprises two arms of two diodes. Thus, some of the parasites coming from the network are not transmitted to the battery and vice versa. According to another additional feature, the step stage comprises a rectifying means connected to the secondary winding of the transformer, said rectifying means comprising only two diodes. This allows a further reduction in the number of components.

According to one embodiment, the rectifying means of the step-up stage comprises: a first diode whose cathode is directly connected to the output stage and the anode is connected directly to a first secondary terminal of the secondary winding Transformer and a second diode whose cathode is directly connected to the output stage and the anode is connected directly to a second secondary terminal of the secondary winding of the transformer. Thus, a rectifying means is realized with only two diodes. According to one characteristic of this embodiment, the step-up stage comprises a Zener diode connected between a primary terminal of the primary winding of the transformer and the step-down stage. Thus, the voltage across the transformer can be controlled to demagnetize it. According to another embodiment, the secondary winding of the transformer comprises three secondary terminals, a first and a third secondary terminal connected respectively to each of the two ends of the secondary winding and a second secondary terminal connected to a midpoint of the secondary winding, and wherein the rectifying means comprises: - a first diode connected between the third secondary terminal and the output stage. a second diode connected between the first secondary terminal and the output stage. Thus, the rectifying means is made with only two diodes for a transformer whose secondary winding has a midpoint.

According to a characteristic of this other embodiment, the primary winding of the transformer has a first primary terminal connected to a midpoint of the primary winding and second and third primary terminals respectively connected to each of the two ends of the primary winding. and wherein the step-up stage comprises a fourth switching means connected in parallel with the primary winding. Thus, one can use the transformer in full alternation. This is advantageous because to transform with a transformer operating in a single alternation the same electromagnetic energy as a transformer operating in full wave you need more winding and a larger magnetic circuit. Another object of the invention is a method of controlling an on-board charger in a motor vehicle for charging a battery of the vehicle comprising an input stage intended to be connected to a supply network, a step-up stage provided with a transformer having a primary winding, a first switching means connected in parallel with at least a portion of the primary winding and a second switching means and a step-down stage provided with an electrical energy storage means and a third switching means connected in series to an input terminal of the step-down stage in which the step-down stage can operate in two configurations, a lowering configuration in which the third switching means is blocked, and a pass-through configuration in which the third switching means is on and the step up can operate in two configurations, a storage configuration wherein the second switching means is on and the first switching means is off and a passing configuration in which the second switching means is off and the first switching means is on, said method comprising: if the peak voltage of the network is greater than the voltage of the battery, an operation of the step-down stage according to a passing configuration and an alternation of two steps: a step of operating the step-up stage according to a storage configuration; a step of operating the step-up stage according to a passing configuration; if the peak voltage of the network is lower than the voltage of the battery, an operation of the stage elevator in a passing configuration and an alternation of two steps: - a step of operation of the step-down stage in a lowering configuration; a step of operating the step-down stage according to a passing configuration. Thus, the charger can be controlled in a simple manner. According to one characteristic, the two configurations of the step-up stage are controlled so that the intensity crossing the electrical energy storage means follows a sinusoidal current setpoint in phase with the current of the electrical network. Other objects, features and advantages will appear on reading the following description given solely as a non-limitative example and with reference to the appended drawings, in which: FIG. 1 illustrates a first embodiment of a charger for battery according to the invention; and - Figure 2 illustrates a second embodiment of the charger of the invention.

In Figure 1, we can see a battery charger to be embedded in a vehicle. This charger is connected as input to a power supply network RES, for example a single-phase alternating network, and output to a battery BAT of the vehicle. The charger thus delivers during the charging of the battery BAT, a direct current from an AC voltage. The battery charger comprises: - an input stage ETE connected to the supply network RES; a voltage step-down stage AB connected by its two input terminals BE1 and BE2 to the input stage ETE; an ETS output stage connected to the BAT battery; and a voltage booster stage EL1 connected on the one hand to the output stage ETS by its two output terminals BS1 and BS2 and on the other hand to the step-down stage AB.

The input stage ETE comprises a capacitor C 1, a transformer TX2, an ETF filter stage and a rectifier stage RED. The ETF filter stage comprises a capacitor C2 and a coil L2. The rectifier stage RED comprises a diode bridge which comprises two arms of two diodes D1, D2, D4, D3. The stage ETE mainly allows to filter and straighten the voltage of the network RES. The step-down stage AB comprises a coil L1, a switching means Q3 having a first terminal BQ31 connected to the first input terminal BE1 and a second terminal BQ32 connected to the coil L1 and a diode D5 having an anode connected to the second input terminal BE2 and a cathode connected to the second terminal of the third switching means BQ32. The lowering stage AB makes it possible in particular to lower the voltage Ve coming from the network. Indeed, as has been mentioned before the battery voltage varies during charging. Thus, at the beginning of the charge, the battery voltage BAT, VBAT is 240 V and then increases as the load reaches 410 volts. It therefore appears that at the start of charging the peak network voltage equal to 325 volts (325 volts for a 230 volt network) is greater than the voltage VBAT.

To allow the lowering of the voltage coming from the network, the stage AB is operated according to two configurations which are described below: a passing configuration, according to which the switching means Q3 (Q3 is on) is closed and the current flowing through the coil L1 increases linearly; and - a lowering configuration in which the switching means Q3 (Q3 is off) is opened and the current flowing through the coil decreases. The stage elevator EL1 comprises: a transformer TX1 provided with a primary winding PR and a secondary winding SE. The primary winding PR has two primary terminals BP1, BP2. Each of the two terminals BP1 and BP2 is connected respectively to one end of the primary winding PR. The secondary winding SE has two secondary terminals BSE1, BSE2. Each of the two terminals BSE1 and BSE2 is respectively connected to one end of the secondary winding SE; a first switching means Q1 connected in parallel with the primary winding PR having a first switching terminal BQ11 connected directly to the first primary terminal BP1 and a second switching terminal BQ12 connected directly to the second input terminal BE2; a second switching means Q2 connected between the second primary terminal BP2 and the second input terminal BE2; a Zener diode DZ connected in parallel with the second switching means Q2, between the second primary terminal BP2 and the second input terminal BE2. The Zener diode DZ used in reverse allows to control the voltage across the transformer. Thus we can nullify the average voltage across the transformer TX1 to ensure its demagnetization; and - DED rectification means. Stage EL1 is a "Forward" electrical assembly according to an Anglo-Saxon term well known to those skilled in the art. Advantageously, the first switching means Q1 comprises only a single switching component. The rectifying means DED comprises: a first diode D6 whose cathode is directly connected to the first output terminal BS1 and the anode is connected directly to the first secondary terminal BSE1; and a second diode D7 whose cathode is directly connected to the first output terminal BS1 and the anode is connected directly to the second secondary terminal BSE2. The elevator stage EL1 makes it possible in particular to raise the voltage coming from the network. Indeed, as mentioned above, the voltage of the battery at the end of charging can reach a value of 410 volts higher than the voltage of the network RES. It therefore appears that during charging, the mains voltage is lower than the voltage VBAT.

To allow the voltage to be raised from the network Ve, the stage EL1 is operated in two configurations which are described below. According to a passing configuration, the switching means Q1 (Q1 is off) are opened and the switching means Q2 (Q2 is on) are closed. Thus, the energy of the network added to that contained in the coil L1 is transmitted to the battery BAT. According to another storage configuration, the switching means Q1 (Q1 is on) are closed and the switching means Q2 are opened (Q2 is blocked). Thus, the energy is stored in the coil L1 and the transformer TX1 is demagnetized. It is also provided by alternating the two configurations of the stage elevator EL1 to achieve an active power factor correction (active power factor correction according to an Anglo-Saxon term well known to those skilled in the art). For this, the current of the coil L1 is compared with a sinusoidal reference in phase with the current of the network RES and one of the two configurations mentioned above is then applied according to this comparison. More precisely, if the coil current L1 is greater than the setpoint then it is necessary to discharge the coil L1 by operating the stage EL1 according to the passing configuration. If, on the other hand, the coil current Ll is lower than the setpoint then the coil must be loaded by operating the stage EL1 according to the storage configuration. Thus, a "Forward" assembly is used to make an elevator stage. It is this same elevator stage which is also used to make an active power factor correction. The ETS output stage comprises a capacitor C3 and a coil L3. The ETS output stage makes it possible in particular to filter the charging current of the battery BAT delivered by the charger.

In Figure 2, we can see another battery charger connected to a RES power supply network and output to a battery BAT. The battery charger of FIG. 2 differs from that of FIG. 1 because of the presence of an elevator stage EL2 which is different from the stage EL1 of the charger of FIG. 1. Stage EL2 of FIG. 2 comprises: a transformer TX1 provided with a primary winding PR and a secondary winding SE. The primary winding PR has three primary terminals BP1, BP2 and BP3. Each of the two terminals BP2 and BP3 is respectively connected to one end of the primary winding PR. Terminal BP1 is connected to a midpoint of the primary winding. The secondary winding SE has three secondary terminals BSE1, BSE2 and BSE3. Each of the two terminals BSE1 and BSE3 is respectively connected to each end of the secondary winding SE. The terminal BSE2 is connected to a midpoint of the secondary winding SE. a first switching means Q1 connected in parallel with a part of the primary winding PR having a first switching terminal BQ11 connected directly to the first primary terminal BP1 and a second switching terminal BQ12 connected directly to the second terminal of BE2 entry; a second switching means Q2 connected between the second primary terminal BP2 and the second input terminal BE2; a fourth switching means Q4 connected in parallel with the whole of the primary winding PR having a first switching terminal BQ41 connected to the third primary terminal BP3 and a second switching terminal BQ42 connected to the second input terminal BE2 ; and - DED rectification means. Stage EL2 is an electrical assembly "Push-Pull" according to an Anglo-Saxon term well known to those skilled in the art. Advantageously, the first switching means Q1 comprises only a single switching component.

The rectifying means DED comprises: a first diode D6 whose anode is connected directly to the third secondary terminal BSE3 and the cathode is connected directly to the first output terminal B Sl. a second diode D7 whose anode is directly connected to the first secondary terminal BSE1 and the cathode is connected directly to the first output terminal B Sl. Just like stage EL1, stage elevator EL2 makes it possible to raise the voltage coming from the network and to ensure an active power factor correction. For this, the EL2 stage is operated according to the following two configurations. The stage can be operated in a passing configuration, in which the switching means Q1 (Q1 is off) is opened and the operation of the switching means Q2 and Q4 is alternated. That is to say in the pass-through configuration, two situations are alternated, a situation in which the switching means Q1 and Q2 are opened (Q1 and Q2 are blocked) and the switching means Q4 (Q4 is on) are closed. and a second situation in which the switching means Q1 and Q4 (Q1 and Q4 are off) are opened and the switching means Q2 (Q2 is on) is closed. Thus, the energy of the network plus that contained in the coil L1 is transmitted to the battery BAT. According to a storage configuration, the switching means Q1 (Q1 is on) are closed and the switching means Q2 and Q4 are opened (Q2 and Q4 are blocked). Thus, the energy is stored in the coil L1. Thus, in the step-up stage EL2, the transformer TX1 operates in double alternation, which is advantageous because to transform with a transformer operating in a single alternation the same electromagnetic energy as a transformer operating in full wave, it is necessary to provide more winding and a Magnetic circuit more important. On the other hand, in full-wave operation, the demagnetization of the transformer TX1 is no longer necessary.

It is also possible by alternating the two configurations of the stage EL2 to perform an active power factor correction. For this, just as in the EL1 stage, the current of the coil L1 is compared, with a sinusoidal reference in phase, with the current of the network RES and one of the two configurations is applied as a function of the comparison. If the coil current is higher than the setpoint, then the coil must be discharged by operating the EL2 stage according to the passing configuration. If, on the other hand, the coil current is lower than the setpoint, then the coil must be loaded by operating the EL2 stage according to the storage configuration. Thus, a "push-pull" assembly is used to make a step-up stage. It is this same elevator stage which is also used to make an active power factor correction.

For the control of stages AB, EL1 or EL2 previously described, two modes of implementation can be considered. According to a first embodiment, it is expected that when the network voltage is greater than that of the battery, then the switching means such as: the stage EL1 or EL2 operates according to only the passing configuration and the configurations passing and lowering of the floor AB are alternated. Thus, by operating the stage AB according to the passing configuration for a duration (a1) .T and following the lowering configuration for a period (1-a1) .T, with T the value of a period, one can lowering the voltage transmitted to the battery BAT by adjusting the factor al according to the formula: Vsn / Ve = al, in which Vsn is the result of the division of the voltage Vs between the terminals BS1 and BS2 by the transformation ratio of the transformer TX1 and Ve the voltage between the terminals BE1 and BE2. As an exemplary embodiment, the alternation of the two configurations mentioned above can be carried out with a control signal in pulse width modulation having a duty cycle al.

According to the first embodiment, it is also provided that when the voltage of the battery is greater than that of the network then the switching means are controlled such that: the passing and storage configurations of the stage EL1 or EL2 are alternated and that the AB stage operates according to the passing configuration. Thus, by operating the stage EL1 or EL2 according to the passing configuration for a duration (a2) .T and according to the storage configuration for a period (1-a2) .T, with T the value of a period, one can raise the voltage transmitted to the battery BAT by adjusting the factor a2 according to the formula: 1-Ve / Vsn = a2, in which Vsn is the result of the division of the voltage Vs between the terminals BS1 and BS2 by the transformation ratio transformer TX1 and Ve the voltage between terminals BE1 and BE2. As an exemplary embodiment, the alternation of the two configurations mentioned above can be performed with a pulse width modulation control signal having a duty cycle a2.

According to another embodiment, it can also be provided that the passing and lowering configurations of the stage AB and the passing and storage configurations of the stage EL1 or EL2 are all alternating.

Claims (11)

REVENDICATIONS1. On-board charger in a motor vehicle for charging a battery (BAT) of the vehicle from a power supply network (RES) comprising: - an input stage (ETE) intended to be connected to said power supply network (RES) ; a voltage step-down stage (AB) connected to the input stage (ETE) and comprising an electrical energy storage means (L1); a voltage booster stage (EL1, EL2); and an output stage (ETS) connected to the step-up stage (EL1, EL2); characterized in that said step-up stage (EL1, EL2) comprises: - a transformer (TX1) provided with a primary winding (PR) and a secondary winding (SE); and a first switching means (Q1) connected in parallel to at least a portion of the primary winding (PR) and comprising only a single switching component. 2. The charger of claim 1, wherein the step (EL1, EL2) comprises a second switching means (Q2) connected between a primary terminal (BP2) of the primary winding (PR) of the transformer (TX1) and an input terminal (BE2) of the step-down stage (AB). 3. Charger according to one of claims 1 and 2, wherein the step-down stage comprises a coil (L1) and a third switching means (Q3) connected in series to a first input terminal (BE1) of the step-down stage (AB) and a diode (D5) having an anode connected to a second input terminal (BE2) of the step-down stage (AB) and a cathode connected between said coil and the third switching means (Q3). 4. The charger according to any one of claims 1 to 3, wherein the input stage (ETE) comprises an input filter stage (ETF) intended to be connected to the power supply network (RES) and a rectifier stage (RED) connected to the voltage step-down stage (AB), said rectifier stage (RED) comprising a diode bridge which comprises two arms of two diodes. 5. Charger according to one of the preceding claims, wherein the step (EL 1, EL2) comprises a rectifying means (DED) connected to the secondary winding (SE) of the transformer (TX1), said rectifying means (DED) comprising only two diodes. 6. The charger of claim 5, wherein the rectifying means (DED) of the step stage (EL1) comprises: - a first diode (D6) whose cathode is connected directly to the output stage (ETS) and the anode is connected directly to a first secondary terminal (BSE1) of the secondary winding (SE) of the transformer (TX1); and a second diode (D7) whose cathode is directly connected to the output stage (ETS) and the anode is connected directly to a second secondary terminal (BSE2) of the secondary winding (SE) of the transformer (TX1 ). 7. Charger according to any one of claims 1 to 6, wherein the step (EL1) comprises a Zener diode (DZ) connected between a primary terminal (BP2) of the primary winding (PR) of the transformer (TX1 ) and the step-down stage (AB). 8. The charger of claim 5, wherein the secondary winding of the transformer comprises three secondary terminals (BSE1, BSE2, BSE3), a first (BSE1) and a third (BSE3) secondary terminals connected respectively to each of the two ends of the secondary winding (SE) and a second secondary terminal (BSE2) connected to a midpoint of the secondary winding (SE), and wherein the rectifying means (DED) comprises: - a first diode (D6) connected between the third secondary terminal (BSE3) and the output stage (ETS). a second diode (D7) connected between the first secondary terminal (BSE1) and the output stage (ETS). 9. Charger according to one of claims 1 to 5 and 8, wherein the primary winding (PR) of the transformer (TX1) has a first primary terminal (BP1) connected to a midpoint of the primary winding and the second and third primary terminals (BP2, BP3) respectively connected to each of the two ends of the primary winding (PR), and wherein the step-up stage (EL2) comprises a fourth switching means (Q4) connected in parallel with the primary winding (PR). 10. A method of controlling an on-board charger in a motor vehicle for charging a battery (BAT) of the vehicle comprising an input stage (ETE) intended to be connected to a power supply network (RES), a step-up stage provided with a transformer (TX1) having a primary winding (PR), a first switching means (Q1) connected in parallel with at least a portion of the primary winding (PR) and a second switching means ( Q2) and a step-down stage provided with an electrical energy storage means (L1) and a third switching means (Q3) connected in series with an input terminal (BE1) of the step-down stage (AB ) in which the down-converter stage (AB) can operate in two configurations, a lowering configuration in which the third switching means (Q3) is off and a passing configuration in which the third switching means (Q3) is conducting and the elevator stage (EL1, EL2) can work r according to two configurations, a storage configuration in which the second switching means (Q2) is on and the first switching means (Q1) is off and a passing configuration in which the second switching means (Q2) is blocked and the first switching means (Q1) is passing, said method comprising: if the peak network voltage (RES) is greater than the battery voltage (BAT), a step-down mode operation in a passing configuration and an alternation of two steps: a step of operation of the step-up stage (EL1, EL2) according to a storage configuration; a step of operating the step-up stage (EL1, EL2) according to a passing configuration; if the peak voltage of the network (RES) is lower than the battery voltage (BAT), an operation of the step-up stage (EL1, EL2) according to a passing configuration and an alternation of two steps: - a step of operation of the step down (AB) in a lowering configuration; a step of operation of the step-down stage (AB) according to a passing configuration. 11. The method as claimed in claim 10, wherein the two configurations of the step-up stage (EL1, EL2) are controlled so that the intensity crossing the electrical energy storage means (L1) follows a sinusoidal current set point. phase with the mains current (RES) .20