WO2010119097A2

WO2010119097A2 - Motor vehicle with electric propulsion and terminal for charging the bank of accumulators of such a vehicle

Info

Publication number: WO2010119097A2
Application number: PCT/EP2010/054968
Authority: WO
Inventors: Serge Loudot
Original assignee: Renault Sas
Priority date: 2009-04-15
Filing date: 2010-04-15
Publication date: 2010-10-21
Also published as: FR2944653B1; WO2010119097A3; FR2944653A1; EP2419988A2

Abstract

The present invention relates to a motor vehicle (200) with electric propulsion comprising a battery (210), a power circuit (220), an electric motor (201) and a plug-in connector (207). It also relates to a charging point (100) for charging the bank of a such a vehicle, comprising a transformer (101), a rectifier (102) and a matching plug-in connector (103). According to the invention, the plug-in connector of the vehicle comprises a first connection terminal (208) connected to the negative terminal (211) of the battery and a second connection terminal (209) connected to the neutral cable (205) of the electric motor. The rectifier of the charging point comprises for its part means for maintaining a constant voltage between the two terminals of its plug-in connector.

Description

Motor vehicle with electric propulsion and terminal for charging the bank of accumulators of such a vehicle

The present invention relates in general to the charging of banks of accumulators (also known as a battery) of rechargeable electric or hybrid motor vehicles (known as "plug-in" hybrid vehicles) .

It relates more particularly to a motor vehicle with electric propulsion comprising a three-phase electric motor comprising three phase cables and one neutral cable, a battery comprising a negative terminal and a positive terminal, and a power circuit with an inverter function comprising two input terminals respectively connected to the negative and positive terminals of the battery, and three output terminals respectively connected to the three phase cables of the three-phase electric motor.

It also relates to a point for charging a battery of such a motor vehicle, comprising a three-phase electric transformer and at least one rectifier which comprises three input terminals connected to the secondary of the three-phase electric transformer and two output terminals connected to at least one plug-in connector suitable for being connected to a matching plug-in connector of the motor vehicle.

TECHNOLOGICAL BACKGROUND

The development of vehicles with electric propulsion of the aforementioned type faces the major problem of the charging time of the battery. The charge of such a battery on a conventional low-voltage domestic electricity network requires several hours. This charging method greatly reduces the availability of the vehicles compared with the availability of a conventional car fitted with an internal combustion engine .

A known solution therefore consists in providing electric points on the model of petrol filling stations. These points are designed to deliver electric power that is much greater than that available on a domestic electricity network, so as to provide a rapid charge of the battery.

For example, document EP 0 553 824 describes an electric point suitable for delivering a three-phase electric current that originates either directly from the external electricity network, or has been previously filtered by electric inductors. As described in this document, all of the means for rectifying the three-phase electric current originating from the external electricity network are incorporated into the vehicle .

In order to be able to be connected to such a point, each motor vehicle must in particular be fitted with three bistable contactors respectively situated on the three output terminals of the power circuit. These contactors therefore make it possible to run the current either between the battery and the electric motor (traction mode) , in which case the power circuit operates as an inverter, or between the charging point and the battery (charging mode) , in which case the power circuit operates as a rectifier.

The major drawback of this technical solution is that, in charging mode, the rectification of the three-phase electric current by the power circuit generates current harmonics in the battery, which causes overheating that can damage this battery. The use of contactors between the power circuit and the electric motor, the said contactors being designed for high currents, is also costly and reduces the efficiency of the vehicle in traction mode.

Document WO 2005/08808 also describes a charging point suitable for delivering a single-phase electric current. As described in this document, all of the means for rectifying the three-phase electric current originating from the external electricity network is incorporated into the charging point.

To be able to be connected to such a charging point, each motor vehicle is then only fitted with a plug-in connector furnished with two connection terminals directly connected to the battery.

The drawback of such a charging point is that it is necessary to ensure that the battery is capable of receiving the single-phase current delivered by the connection terminal. It is therefore essential to provide a costly means of communication between the charging point and the vehicle.

SUBJECT OF THE INVENTION

The object of the present invention is to propose a low-cost solution for charging banks of accumulators of motor vehicles.

Accordingly, the proposal according to the invention is a motor vehicle as defined in the introduction, which comprises means for charging the battery comprising two connection terminals to be connected to an external electricity network, including a first connection terminal connected to the negative terminal of the battery and a second connection terminal connected to the neutral cable of the three-phase electric motor. Also proposed is a charging point as defined in the introduction, in which the rectifier comprises means for maintaining a constant voltage between its two output terminals.

Therefore, by virtue of the invention, the means for rectifying and regulating the three-phase electric current originating from the external electricity network are incorporated partly into the charging point and partly into the motor vehicle.

The portion situated in the charging point, outside the motor vehicle, makes it possible to rectify the current so as to supply the vehicle with a stabilized direct- current voltage which is independent, on the one hand, of the upstream variations from the transformer, and, on the other hand, of the current drawn by the battery to be charged.

The portion situated in the motor vehicle, for its part, makes it possible to regulate the current and the voltage according to the intrinsic characteristics of the battery, so as to comply with its charging cycle. Accordingly, this portion uses only the electric components already present for the traction of the vehicle (the power circuit) , components that are dimensioned to withstand considerable currents.

This provides a sharing of the functions between the charging point and the vehicle, which allows the latter to operate independently of one another, with no communication protocol, and using only the electric components already present on the vehicle. This solution is therefore particularly low-cost.

Other advantageous and non-limiting features of the motor vehicle according to the invention are as follows : the two connection terminals form a male or female plug-in connector to be connected to a matching plug-in connector of a charging point connected to the external electricity network;

the power circuit comprises, on the one hand, three arms which are connected in parallel between the said two input terminals and which are each fitted with two pairs of chopping switches/diodes connected in series on either side of a mid-point forming one of the output terminals, and, on the other hand, a driving unit for driving the said chopping switches in inverter mode so that the battery powers the three-phase electric motor or in step-up voltage mode in order to charge the battery via the external electricity network.

Other advantageous and non-limiting features of the charging point according to the invention are as follows :

the rectifier being an alternating dual rectifier, the said maintenance means comprise four arms connected in parallel between the two output terminals including one capacitive arm fitted with a capacitor and three switch arms each fitted with two one-way dipoles connected in series on either side of a mid-point connected to one of the input terminals;

the said one-way dipoles are made up of diodes;

the said one-way dipoles are made up of thyristors or of MOSFET or IGBT transistors and in which the rectifier comprises means for driving the said one-way dipoles; means are provided for filtering current harmonics, the said means being active or passive, interposed between the secondary of the three- phase electric transformer and the three input terminals of the rectifier;

the rectifier being a pulse-width-modulation rectifier, the said maintenance means comprise four arms connected in parallel between the two output terminals, including one capacitive arm fitted with a capacitor and three switch arms each fitted with two pairs of chopping switches/diodes connected in series either side of a mid-point connected to one of the input terminals;

the rectifier comprises closed-loop control driving means of the said chopping switches;

an energy storage element is provided connected to the said plug-in connector, in parallel with the rectifier .

DETAILED DESCRIPTION OF AN EMBODIMENT

The following description, with respect to the appended drawings, given as a non-limiting example, will clearly explain what the invention consists in and how it can be embodied.

In the appended drawings:

Figure 1 is a wiring diagram in which the electric components of a motor vehicle and of a charging point according to the invention appear;

Figure 2 is a wiring diagram of a Buck converter; Figures 3 to 5 are wiring diagrams of three variant embodiments of the charging point of Figure 1 ;

- Figures 6 and 7 are wiring diagrams of two variant embodiments of the rectifier of the charging point of Figure 1 ;

Figure 8 is a diagram representing the control loop of the rectifier of Figure 7; and

Figure 9 is a schematic view of another variant embodiment of the charging point of Figure 1.

Figure 1 shows the electric circuits of a charging point 100 and of a motor vehicle 200 with electric propulsion .

As shown in this figure, the motor vehicle 200 comprises a three-phase electric motor 201, a battery 210, a power circuit 220 interposed between the battery 210 and the electric motor 201, and a plug-in connector 207 (male or female) comprising exclusively two connection terminals 208, 209.

The charging point

The charging point 100 is designed to charge at a high speed the battery 210 of the motor vehicle 200.

For this purpose, it comprises a three-phase electric transformer 101 connected to a three-phase external electricity network, at least one rectifier 102 and at least one plug-in connector 103 (male or female) suitable for being attached to the plug-in connector 207 of the motor vehicle 200. The three-phase electric transformer 101 is in this instance a voltage step-down transformer (medium voltage/low voltage) . Conventionally it has a primary connected to the external electricity network and a secondary to which the input terminals of each rectifier 102 are connected.

As a variant, it is possible for there to be a plurality of secondaries to each of which a rectifier is connected.

As shown in Figures 3 to 5, the charging point 100 is preferably provided to comprise at least two distinct plug-in connectors 103 so that several vehicles can come to charge their battery banks of accumulators simultaneously at this charging point.

As shown in Figure 3, the charging point 100 comprises a single rectifier 102 and the various plug-in connectors 103 are connected in parallel to the output terminals of this rectifier 102. This technical solution is not very expensive. It requires the provision of only one rectifier 102 that can deliver a current of considerable intensity. By virtue of this solution, the voltage is the same at the terminals of each plug-in connector 103.

As a variant, as shown in Figure 5, it is possible to provide for the charging point 100 to comprise a plurality of rectifiers 102 and for each plug-in connector 103 to be powered by a rectifier 102 specific to it. In this variant, the rectifiers 102 are powered in parallel by the transformer 101. By virtue of this solution, the voltages proposed at the terminals of each plug-in connector 103 can be different. This technical solution will make it possible, for example, to propose one plug-in connector for the vehicles requiring a low voltage (motor cycles etc.) and one plug-in connector for the other vehicles.

Also as a variant, as shown in Figure 4, it is possible to provide an intermediate solution in which the charging point 100 comprises a plurality of rectifiers 102 and in which various plug-in connectors 103 are connected in parallel to the output terminals of each rectifier 102.

As is shown more particularly in Figures 6 and 7, each rectifier 102 comprises three input terminals ElO, Ell, E12 (E20, E21, E22 in Figure 7) connected to the secondary of the three-phase electric transformer 101 and two output terminals SlO, SIl (S20, S21 in Figure 7) connected to the plug-in connector (s) 103.

According to a particularly advantageous feature of the invention, the rectifier 102 comprises means for maintaining a constant voltage between its two output terminals SlO, SIl (S20, S21 in Figure 7), equal to a predetermined value irrespective of the voltage at the primary of the transformer 101 and the current delivered by each plug-in connector 103.

This rectifier 102 is more precisely, in this instance, an alternating dual rectifier. It can be uncontrolled, phase-controlled (Figure 6) or pulse-width modulated (Figure 7) .

The maintenance means of the rectifier 102 comprise more precisely four arms connected in parallel between its two output terminals SlO, SIl (S20, S21 in Figure 7), including one capacitive arm 114 (124) fitted with a capacitor 119 (129 in Figure 7) and three switch arms 111, 112, 113 (121, 122, 123 in Figure 7) each fitted with at least two dipoles connected in series on either side of a mid-point connected to one of its input terminals ElO, Ell, E12 (E20, E21, E22 in Figure 7) .

In the first embodiment shown in Figure 6, the rectifier 102 is a full-wave rectifier. Each switch arm 111, 112, 113 then comprises exactly two one-way dipoles 118 connected in series on either side of one of the input terminals ElO, Ell, E12, in order to be on-state in the same direction.

These one-way dipoles are preferably controlled. For this purpose they may consist of thyristors 118, or of MOSFET or IGBT transistors.

To drive these controlled dipoles 118, the rectifier 102 comprises means 116 for measuring the voltage U₃ between its two output terminals SlO, SIl and driving means 115 making it possible to control the moment when the controlled dipoles 118 are switched on as a function of the measured voltage U₃. The driving is then carried out by a simple law, for example a proportional integral, which takes action only on the moment when the controlled dipoles 118 are switched on.

The driving means 115 therefore make it possible to regulate the voltage at the terminals of each plug-in connector 103, by advancing the moment at which the controlled dipoles 118 are switched on in the case of voltage drop at the primary of the transformer 101 and by retarding this moment of switching on in the event of a rise in voltage.

As a variant, provision can be made for the one-way dipoles to be uncontrolled and to consist of simple diodes, on condition of course that the voltage at the primary of the transformer 101 is sufficiently stable. The rectifier 102 will then have no driving means and - li ¬

the diodes will switch at the frequency of the external electricity network.

Whichever the unidirectional dipoles chosen, the latter generate harmonics of the current, some of which have to be filtered to avoid being transmitted to the external electricity network.

The charging point 100 then comprises means 117 for filtering certain harmonics of the current, which means being interposed between the secondary of the three- phase electric transformer 101 and the three input terminals ElO, Ell, E12 of the rectifier 102.

These filtering means 117 may be passive. They will then comprise a set of electric components (capacitors, inductors, resistors, etc.) the resonance frequency of which will be tuned to the ranks of the harmonics to be filtered (in particular to the fifth rank) .

As a variant, these filtering means 117 may be active. They will then comprise an electric converter suitable for injecting to the secondary of the three-phase electric transformer 101 an electric signal having harmonics of the same amplitude and in phase opposition to the harmonics to be filtered.

In the second embodiment shown in Figure 7, the rectifier 102 is a pulse-width modulation rectifier. Each switch arm 121, 122, 123 then comprises two pairs of chopping switches/diodes 128 connected in series on either side of one of the input terminals E20, E21, E22.

To drive these chopping switches, the rectifier 102 comprises : means 126 for measuring the output voltage U₃ between its two output terminals S20, S21,

means 127A for measuring the input voltage U_e at the input terminals E20, E21, E22,

means 127B for measuring the input intensity I_e traversing the input terminals E20, E21, E22, and

- means 125 for closed-loop driving of the chopping switches as a function of the measured voltages U_e, U₃ and intensity I_e.

In this mode, all of the measured data make it possible to log in not only the voltage at the terminals of the plug-in connector 103, but also the intensity of the current absorbed on the external electricity network, so as to ensure that the rectifier 102 generates only a few harmonics in the external electricity network.

More precisely, as shown in Figure 7, the driving means 125 comprise a control loop 130 comprising, on the one hand, a slow loop 131 which locks in the output voltage U₃ at the output terminals S20, S21 of the rectifier 102 and which supplies a set point of input current I_COn_s to be absorbed on the external electricity network, followed, on the other hand, by a fast loop 132 which locks in the intensity of the input current I_e absorbed on the external electricity network and which supplies a set point T_con3 for driving the chopping switches.

The slow loop 131 comprises at the input a subtractor 133 which calculates the difference between the set point voltage U_ref desired at the output terminals S20, S21 (for example 400 V) and the real measured output voltage U₃. This subtractor 133 is followed by a corrector 134 which makes it possible to calculate a difference of current DIi. This slow loop 131 also comprises generation means 135 suitable for generating a set point profile K as a function of the phase of the input voltage U_e .

The slow loop finally comprises a multiplier element 136 which makes it possible to determine the set point of input current Icons to be absorbed on the external electricity network as a function of the set point profile K and of the current difference DIi.

The fast loop 132 for its part comprises at the input a subtractor 137 which calculates the difference between this input current set point I_COns and the real measured input current I_e. This subtractor 137 is followed by a corrector 138 and regulator 139 programmed according to a modulation strategy, in order to determine the set point T_cons for driving the chopping switches of the rectifier 102.

The driving means 125 are therefore programmed to open the chopping switches so that the rectifier 102 absorbs a sine-wave current in phase with the current of the external electricity network, which avoids the necessity of providing costly anti-harmonics filters.

The rectifier 102 may if necessary also comprise a low- cost EMC (electromagnetic compatibility) filter in order, on the one hand, to isolate the charging point 100 from the electromagnetic disturbance present on the external electricity network, and, on the other hand, prevent this charging point 100 from generating such disturbance in the external electricity network.

The motor vehicle

As shown in Figure 1, the three-phase electric motor 201 of the motor vehicle 200 has a single winding. It comprises three phase cables 202, 203, 204 in a star pattern stator winding, and a neutral cable 205 which extends from the centre of the star formed by the three phase cables 202, 203, 204.

The battery 210 is, for its part, a high-capacity battery, for example of the lithium-ion type. Conventionally it comprises a negative terminal 211 and a positive terminal 212. The bank of batteries must have a voltage between its terminals that is always higher than the direct-current voltage of the recharging point. This battery is moreover fitted with a controller (not shown) which makes it possible to control the charging current which enters its positive terminal 212.

The power circuit 220 has an inverter-based function. It comprises two input terminals El, E2 respectively connected to the negative terminal 211 and positive terminal 212 of the battery 210, and three output terminals Sl, S2, S3 respectively connected to the three-phase cables 202, 203, 204 of the three-phase electric motor 201.

The power circuit 220 also comprises three arms 221, 222, 223 which are connected in parallel between the said two input terminals El, E2 and which are each fitted with two pairs of chopping switches/diodes Tll/Dll, T12/D12, T21/D21, T22/D22, T31/D31, T32/D32 connected in series on either side of a mid-point forming one of the said output terminals Sl, S2, S3.

The power circuit 220 finally comprises a driving unit 230 for driving its chopping switches TIl - T32.

According to a particularly advantageous feature of the invention, one of the two connection terminals 208 of the plug-in connector 207 of the motor vehicle 200 is connected to the negative terminal 211 of the battery 210 while the other of its two connection terminals 209 is connected to the neutral cable 205 of the three- phase electric motor 201.

The driving unit 230 is designed to drive the chopping switches TIl - T32 in charging mode (or in step-up voltage mode) when the plug-in connector 207 of the vehicle 200 is connected to the plug-in connector 103 of the charging point 100, and in traction mode (or inverter mode) otherwise.

In traction mode, the direct current originating from the battery 210 is therefore transformed by the power circuit 220 into a three-phase current which makes it possible to power the electric motor 201.

In charging mode, the chopping switches TIl - T32 are, on the other hand, driven so that each arm of the power circuit 220 behaves like a voltage step-up element.

More precisely they are driven like a Buck converter

(see Figure 2) . The electric motor 201 being stopped

(engaged on the wheels of the vehicle) , each of its stator windings can be used as a filtering inductor.

The driving unit 230 can then lock in the current originating from the charging point 100 so as to supply the battery 210 with the charging current required by its controller. The chopping switches of each arm 221, 222, 223 are more precisely driven relative to one another with a phase shift of 2. Pi/3 so as to limit the current harmonics travelling in the neutral cable 205 of the motor.

The present invention is in no way limited to the embodiments described and shown, but those skilled in the art will be able to contribute thereto any variant conforming to its spirit. In particular, as shown in Figure 9, it is possible to provide that the charging point 100 comprises an energy storage element 104 connected to the plug-in connector 103, in parallel with the rectifier 102. The energy storage element 104 will then be chosen to deliver a direct-current voltage of the order of magnitude of the set point voltage of the rectifier (for example

200 volts) . This energy storage element 104 may for example consist of a battery or else a supercapacitor .

Such an energy storage element 104 will make it possible in particular to buy electricity at off-peak times during which it is not very costly, in order to deliver it in peak times. Switches 106, 107 provided between the energy storage element 104 and the plug-in connectors 103 on the one hand, and between the rectifier 102 and the plug-in connectors 103 on the other hand will then make it possible to switch from one electricity supply mode to the other.

It will also be possible to have this energy storage element 104 coupled to a stand-alone energy production device 105 (solar panels, wind turbine, etc.) making it possible to charge the energy element 104. In this way, the quantity of energy absorbed from the external electricity network to charge the banks of accumulators of the motor vehicles will be reduced.

In particular, having a charging point 100 fitted with a plug-in connector 103, solar panels and/or a wind turbine will therefore produce the energy necessary for one's vehicle in an independent manner.

An operator having a charging point 100 fitted with several plug-in connectors 103, solar panels and/or a wind turbine can, for his part, reduce the quantity of energy captured from the external electricity network.

Claims

1. Motor vehicle (200: with electric propulsion, comprising :

a three-phase electric motor (201) comprising three phase cables (202 - 204) and a neutral cable (205),

a battery (210) comprising a negative terminal (211) and a positive terminal (212),

a power circuit (220) with an inverter function, comprising two input terminals (El, E2) respectively connected to the negative terminal (211) and to the positive terminal (212) of the battery (210), and three output terminals (Sl, S2, S3) respectively connected to the three phase cables (202 - 204) of the three-phase electric motor (201),

characterized in that it comprises means for charging the battery (210) comprising two connection terminals (208, 209) to be connected to an external electricity network, including a first connection terminal (208) connected to the negative terminal (211) of the battery (210) and a second connection terminal (209) connected to the neutral cable (205) of the three-phase electric motor (201) .

2. Motor vehicle (200) according to Claim 1, in which the two connection terminals (208, 209) form a male or female plug-in connector (207) to be connected to a matching plug-in connector (103) of a charging point (100) connected to the external electricity network.

3. Motor vehicle (200) according to one of the preceding claims, in which the power circuit (220) comprises :

- three arms (221 - 223) which are connected in parallel between the said two inlet terminals (El, E2) and which are each fitted with two pairs of chopping switches/diodes (TIl - T32, DIl - D32) connected in series on either side of a mid-point forming one of the said output terminals (Sl S3), and

a driving unit (230) for driving the said chopping switches (TIl - T32) in inverter mode so that the battery (210) powers the three-phase electric motor (201) or in step-up voltage mode in order to charge the battery (210) via the external electricity network.

4. Point (100) for charging a battery of a motor vehicle according to one of the preceding claims, comprising :

a three-phase electric transformer (101),

at least one rectifier (102) comprising three input terminals (ElO - E12; E20 - E22) connected to the secondary three-phase electric transformer

(101) and two output terminals (SlO, SIl; S20, S21) connected to at least one plug-in connector

(103) suitable for being connected to a matching plug-in connector (207) of the motor vehicle

(200),

characterized in that the rectifier (102) comprises means for maintaining a constant voltage between the two output terminals (SlO, SIl; S20, S21) .

5. Charging point (100) according to the preceding claims, in which the rectifier is an alternating dual rectifier and in which the said maintaining means comprise four arms connected in parallel between the two output terminals (SlO, SIl) including one capacitive arm (114) fitted with a capacitor (119) and three switch arms (111 - 113) each fitted with two oneway dipoles (118) connected in series on either side of a mid-point connected to one of the input terminals (ElO - E12) .

6. Charging point (100) according to the preceding claims, in which the said one-way dipoles are made up of diodes.

7. Charging point (100) according to Claim 6, in which the said one-way dipoles are made up of thyristors or of MOSFET or IGBT transistors and in which the rectifier (102) comprises means (115) for driving the said one-way dipoles.

8. The charging point (100) according to one of Claims 5 to 7, comprising means (117) for filtering the harmonics of current, the said means being active or passive, interposed between the secondary of the three- phase electric transformer (101) and the three input terminals (ElO - E12) of the rectifier (102) .

9. Charging point (100) according to Claim 4, in which the rectifier is an alternating and pulse-width modulation dual rectifier and in which the said maintenance means comprise four arms connected in parallel between the two output terminals (S20, S21), including one capacitive arm (124) fitted with a capacitor (129) and three switch arms (121 - 123) each fitted with two pairs of chopping switches/diodes (128) connected in series on either side of a mid-point connected to one of the input terminals (E20 - E22) .

10. Charging point (100) according to the preceding claim, in which the rectifier (102) comprises closed- loop control driving means (125) of the said chopping switches.

11. Charging point (100) according to one of Claims 4 to 10, comprising an energy storage element (104) connected to the said plug-in connector (103) in parallel with the rectifier (102) .