METHOD FOR RECHARGING ENERGY ACCUMULATION MEANS FITTED TO AN ELECTRIC OR HYBRID VEHICLE

Abstract

The invention relates to a method for recharging an electrical energy source (S) on-board an electric or hybrid vehicle, comprising at least two electric traction motors (M1,M2) respectively associated with a first and second traction converter (C1,C2) and a control electronics (E), said vehicle functioning according to a traction mode using electrical energy provided by the electrical energy source (S), according to a braking mode for recharging said electrical energy source (S) during braking or deceleration phases, and according to a shutdown recharge mode for recharging said electrical energy source (S) during the shutdown phases of the vehicle, characterized in that it consists of utilizing the control electronics (E) managing the traction converters (C1,C2) to carry out a static reconfiguration both of the two converters (C1,C2) and of the motors (M1,M2), in order to transform said converters (C1,C2) associated with the motors (M1,M2) into a charger for the on-board energy source (S).

Claims

1. Method for recharging an electrical energy source (S) on-board an electric or hybrid vehicle, comprising at least two electric traction motors (M1,M2) respectively associated with a first traction converter (C1) and a second traction converter (C2) and a control electronics (E), said vehicle functioning according to a traction mode (T) using electrical energy provided by the electrical energy source (S), according to a braking mode for recharging said electrical energy source (S) during braking or deceleration phases, and according to a shutdown recharge mode for recharging said electrical energy source (S) during the shutdown phases of said vehicle, said method consisting in utilizing the control electronics (E) managing the traction converters (C1,C2) to perform a reconfiguration both of the two converters (C1,C2) and also of the motors (M1,M2), in order to transform said converters (C1,C2) and said motors (M1,M2) into a charger for the on-board energy source (S), characterized in that during a vehicle shutdown phase, a fixed electrical supply grid (R) is connected to the first traction converter (C1) to provide a reference DC electrical voltage U.sub.R and to reconfigure the motors (M1, M2): the neutrals of the two stator windings of said motors (M1, M2) are connected in series by means of a first switch (I1) ordered in closing position by the control electronics (E), which also manage other switches or commutation devices, in order to reconfigure the traction converters (C1, C2); the voltage U.sub.B is measured at the terminals of the on-board electric energy source (S); the control electronics (E) is used to compare the electrical voltage U.sub.B to the reference electrical voltage U.sub.R; if the voltage U.sub.B is lower than the reference voltage U.sub.R, a reconfiguration is performed consisting in transforming the first converter (C1), supplied directly with the reference voltage U.sub.R, into a buck-chopper circuit for regulating the current supplied to the on-board electric energy source (S), the second converter (C2) being in an inhibited state; if the voltage U.sub.B is greater than or equal to the reference voltage U.sub.R, a reconfiguration is performed consisting in transforming the second converter (C2), into a boost-chopper circuit for regulating the current supplied to the on-board electric energy source (S), the first converter (C1) being in an inhibited state; the closure of the first switch (I1) is ordered; and the opening of a second switch (I2) is ordered connecting the first traction converter (C1) to the energy source (S), the second traction converter (C2) remaining connected to said energy source (S).

2. Method for recharging according to claim 1, characterized in that it consists in using a reference voltage U.sub.R produced by a converter (P) rectifying a single or three-phase AC supply grid voltage.

3. Method for recharging according to claim 2, characterized in that the converter (P) is on-board.

4. Method for recharging according to claim 1, characterized in that it consists in using a reference voltage U.sub.R coming directly from a DC voltage supply source.

5. Use of an electrical axle comprising two electric motors (M1, M2) in order to implement the method according to claim 1.

6. Use according to claim 5, characterized in that the electric motors (M1, M2) are in-wheel motors.

7. Use according to claim 5, characterized in that the electrical axle equips an individual vehicle.

8. Use according to claim 5, characterized in that the electrical axle equips a public transport vehicle like a bus or tram.

Description

[0032] Other features and advantages of the invention will also be apparent from the drawings given by way of illustrative and non-limiting examples wherein:

[0033] FIG. 1 is a functional diagram illustrating the method for recharging according to the invention, when the electric or hybrid vehicle is in an operating mode corresponding to a traction mode;

[0034] FIG. 2 shows a functional diagram illustrating the method for recharging according to the invention, when the electric or hybrid vehicle is in an operating mode corresponding to a braking mode, and

[0035] FIG. 3 shows a functional diagram illustrating the method for recharging according to the invention, when the electric or hybrid vehicle is in shutdown recharge mode.

DETAILED DESCRIPTION OF THE FIGURES

[0036] FIG. 1 illustrates the method for recharging according to the invention when the vehicle is in traction mode, i.e., when control electronics E receives a torque and/or speed instruction C.sub.vc.

[0037] The motorization consists of a first motor M1 and a second motor M2, for example electric motors of the in-wheel motor type; each motor is associated with a respective traction converter C1 and C2, which are also called inverters.

[0038] A torque or speed instruction C.sub.vc is then transmitted by any known means to the control electronics E. This latter is interconnected to the traction converters C1 and C2 as well as to the on-board electric energy source S.

[0039] A converter rectifying the electrical voltage or rectifier bridge P, for example on-board, is connected to the first traction converter C1. Such a converter or rectifier bridge P makes it possible to rectify a voltage from a single or three-phase AC electrical supply grid. The rectifier bridge P only intervenes during the recharging phase when the vehicle is shutdown.

[0040] According to another implementation example, it is possible to use a reference electric voltage U.sub.R coming directly from a DC voltage supply source, thus avoiding the use of an on-board rectifier bridge.

[0041] The control electronics E makes it possible to maintain the stator windings of the traction motors M1 and M2 in a disconnected state. Such a disconnection state is obtained by means of switching devices indicated schematically by a first switch I1 that is managed by the control electronics E. The first switch I1 is held open in this traction mode.

[0042] In shutdown recharge mode, each converter C1, C2 is advantageously constituted of three arms used in interlaced manner in order to reduce the phase current, thus reducing the current ripple.

[0043] The windings of the electric motors M1, M2 are implemented such that the neutrals can be accessible for connection thereof.

[0044] In traction operating mode, the traction motors M1 and M2 are supplied with electrical energy from the source S. These supplies, indicated schematically by the arrow T, are provided by means of the traction converters C1 and C2. A switching devices, indicated schematically by the second switch I2, commanded to closed position via control electronics E, makes it possible to connect the first converter C1 to the on-board energy source S. The flow of power transmitted in this operating mode is therefore indicated schematically by the arrow T.

[0045] Such a power supply is known as such, and will not be described in more detail.

[0046] FIG. 2 illustrates the method according to the invention in a recharging phase, and more specifically when the electric or hybrid vehicle is in an operating phase corresponding to braking or deceleration.

[0047] In such an operating mode the traction motors M1 and M2 are transformed into current generators that supply the energy source S through the converters C1 and C2.

[0048] This operating mode, called braking mode, known as such and managed by the control electronics E, is of course initiated by a braking or deceleration instruction Cf. The recharging of the energy source S is indicated schematically using the arrow F in FIG. 2. The switches I1 and I2 remain respectively in open and closed position in this braking mode.

[0049] In traction mode, as in braking mode, the converters C1 and C2 are connected in parallel to the on-board energy source S.

[0050] FIG. 3 illustrates an operating phase corresponding to a shutdown recharging of the vehicle. This shutdown recharge mode corresponds to the connection of the rectifier bridge P to an electrical supply of the electric grid, providing an AC voltage U.sub.R. The control electronics E then makes it possible to reconfigure the traction motors M1 and M2 by connecting their stator windings in series and more precisely the neutrals of said motors M1, M2. This connection is obtained by means of switching devices indicated schematically by the first switch I1, which is ordered into closed position. At the same time, the second switch I2 is ordered into open position by the control electronics E.

[0051] In this shutdown recharge mode, the control electronics E make it possible to reconfigure the traction converters C1 and C2. The electronic components used in the control electronics E in order to implement such a reconfiguration are known as such.

[0052] The reconfiguration therefore consists first in measuring the electric voltage U.sub.B at the terminals of the on-board electric energy supply and in using the control electronics E to compare said voltage U.sub.B to the rectified electrical voltage U.sub.R of the fixed supply grid.

[0053] The method according to the invention then consists in adapting the static reconfiguration of the converters C1 and C2, depending upon the result of the comparison between the electrical voltage U.sub.B and the electrical voltage U.sub.R.

[0054] If the electric voltage U.sub.B is lower than the electric voltage U.sub.R, the reconfiguration consists in transforming the first converter C1 into a buck-chopper circuit for regulating the current delivered to the on-board energy source S. The latter is then recharged by means of the reconfigured second converter C2, as is indicated schematically by the arrow A in FIG. 3. The second converter C2 is then inhibited by forcing open the IGBT semiconductors of said second converter C2.

[0055] Conversely, if the electric voltage U.sub.B is greater than or equal to the electric voltage U.sub.R, the reconfiguration consists in transforming the second converter C2, into a boost-chopper circuit for regulating the current delivered to the on-board electric energy source S. The latter is then recharged via the reconfigured second converter C2, as is indicated schematically by the arrow A in FIG. 3. The first converter C1 is then inhibited. The IGBT semiconductors of the first converter C1 are driven open thus rendering it transparent.

[0056] In one or other of the reconfigurations of the converters C1 and C2, the stator windings of the motors M1 and M2 remain connected in series by the neutrals thereof. The switches I1 and I2 therefore remain ordered respectively into closed and open position during the shutdown recharging mode. During these two reconfigurations, the on-board energy source S, the converters C1 and C2, and the rectifier bridge P remain connected in cascade.

[0057] The recharging method according to the invention finds application thereof particularly in a vehicle of bus or tram type or in an individual vehicle, having at least one electrical axle. The latter has for example two independent in-wheel motors. The corresponding wheels can be mechanically linked or not.

[0058] According to another example according to the invention, the method is implemented with two independent electric motors arranged outside the wheels.

[0059] For example, the electric voltage provided by the fixed grid U.sub.R is single phase 230 V at 50 Hz or three-phase 400 V at 50 Hz. Thus, the rectified AC voltage of 400 V corresponds to the DC voltage U.sub.R of 540 V.

[0060] During the transition from one reconfiguration to another, especially during the transition from the buck-chopper circuit to a boost-chopper circuit, i.e., during the disabling of the buck-chopper circuit and the activation of the boost-chopper circuit, a hybrid operation can be initiated. During this transition, the buck and boost chopper circuits operate simultaneously, thereby obtaining a smooth transition. The buck-chopper circuit will gradually ramp down in favor of the boost-chopper circuit.

[0061] It is obvious that this description is not limited to the examples explicitly described, but that it also includes other embodiments and/or implementations. Thus, a described technical feature can be replaced by an equivalent technical feature, without departing from the scope of the present invention. In the same way, a described step can be replaced by an equivalent step, without departing from the scope of the present invention.