Patent Application
20200016991
The present invention relates to a conversion device for an electric vehicle, enabling electric energy to be transferred between a DC power supply and an N-phase AC power supply, N being an integer higher than or equal to 1. The invention also relates to a method for controlling such a conversion device and a vehicle including such a device.
The invention is applicable to the field of electric converters, in particular electric converters for electric or hybrid vehicles.
An electric vehicle, respectively a hybrid vehicle, includes an electric energy source for providing energy necessary for actuating an electric traction motor to ensure vehicle propelling. The energy source is generally an onboard battery for supplying the traction motor through an inverter.
Yet, the battery can only store a limited amount of energy, and thus requires to be regularly recharged from another, more powerful, energy source, such as a home electric power supply. During the recharging operation, a charger sends the energy from the power supply to the battery to charge it.
The electric or hybrid vehicle is also likely to restore its stored energy to the electric power supply: this is called “V2G” (for “Vehicle to Grid”). In this case, a power electronic element is provided to send this energy to the electric power supply.
All these operations should be made in compliance with electromagnetic compatibility and security standards, and should be controlled by an efficient control system.
Generally, these operations are ensured by distinct power electronic devices, such as for example, an inverter, a charger, a DC-DC converter.
The multiplicity of such pieces of equipment results in a high bulk, heat stresses requiring a cooling system able to cool all of these pieces of equipment, as well as a high manufacturing cost.
Document WO 2010/057892 A1 describes a conversion device for an electric vehicle in which the inverter and charger functions of an electric vehicle are integrated in a same member.
However, such a conversion device is not fully satisfactory.
Indeed, such a device comprises two distinct branches for three phases, which makes its manufacture complex and expensive. Further, such a conversion device requires a specific electric motor necessitating a particular mechanical actuation to switch from one operating mode to another. Further, such a conversion device does not include any galvanic insulation element likely to prevent electric risks to people and the equipment.
One purpose of the invention is thus to provide a conversion device having a bulk and a manufacturing cost which are lower than the conversion devices of the state of the art, while having a simpler and more secure operation.
To that end, one object of the invention is a conversion device of the aforementioned type, including:
Indeed, thanks to such a conversion device, no mechanical actuation is required to switch from one operating mode to another. The operation of such a conversion device is thus simplified.
Further, in such a conversion device, a single circuit is able to make the various conversion operations, which results in a lesser bulk and a lower manufacturing cost than the conversion devices of the state of the art. Such an integration of functions further leads to the use of a single cooling circuit, which further reduces the bulk due to the conversion device.
Further, the presence of the transformer ensures a galvanic insulation between the direct current elements and the alternating current elements, which results in limiting electric risks to people and the equipment.
According to other advantageous aspects of the invention, the conversion device includes one or more of the following characteristics, taken alone or according to any technically possible combinations:
Further, one object of the invention is a method for controlling a conversion device as defined above, the DC-DC converter being connected to a DC power supply through the first low voltage terminal and through the second low voltage terminal, the method including, during a pulling phase, the steps of:
According to other advantageous aspects of the invention, the method includes one or more of the following characteristics, taken alone or according to any technically possible combinations:
Further, another object of the invention is an electric or hybrid vehicle including a battery, an electric motor and a conversion device as defined above, the DC-DC converter being connected to the battery through the first low voltage terminal and through the second low voltage terminal, each connection point of the AC-DC converter being adapted to be connected to a corresponding phase of the electric motor.
The invention will be better understood upon reading the description that follows, given only by way of non-limiting example and made in reference to the appended drawings on which:
An electrification line 2 according to the invention is represented in
The electrification line 2 comprises a conversion device 4, configured to transfer electric energy between a DC power supply and an N-phase AC power supply, N being an integer higher than or equal to 1.
The DC power supply consists of a battery 6.
The AC power supply consists of an electric motor 8 or an alternating current distribution system 10.
The conversion device 4 includes a DC-DC converter 12, an AC-DC converter 14 and a controller 15.
The DC-DC converter 12 is configured to convert a first DC voltage into a second different DC voltage.
The AC-DC converter 14 is configured to convert a DC voltage into an AC voltage, and to convert an AC voltage into a DC voltage.
The DC-DC converter 12 includes a low voltage branch 16, a high voltage branch 18, a first switch 20, a second switch 22 and a transformer 24.
The low voltage branch 16 is connected between a first low voltage terminal 26 and a second low voltage terminal 28. Further, the high voltage branch 18 is connected between a first high voltage terminal 30 and a second high voltage terminal 32.
As is apparent in
The low voltage branch 16 and the high voltage branch 18 each comprise two sub-branches 34 in series, connected to each other at a middle point 36.
Each sub-branch 34 includes a switching module 38 able to switch between an OFF state preventing an electric current from flowing, and an ON state enabling an electric current to flow.
For example, each switching module 38 comprises a transistor 40 and a diode 42 in parallel, the diode being reversely connected with respect to the transistor 40. For example, the transistor 40 is a MOSFET transistor or an IGBT transistor.
The first switch 20 is connected between the first low voltage terminal 26 and the first high voltage terminal 30. Further, the second switch 22 is connected between the second low voltage terminal 28 and the second high voltage terminal 32.
The first switch 20 and the second switch 22 are each able to switch between an OFF state preventing an electric current from flowing, and an ON state enabling an electric current to flow.
The transformer 24 comprises a primary winding 44 and a secondary winding 46 magnetically coupled to each other.
The primary winding 44 is connected, through one of its ends, to the middle point 36 of the low voltage branch 16, and through the other of its ends, to a primary voltage reference.
For example, and as illustrated by
The secondary winding 46 is connected, through one of its ends, to the middle point 36 of the high voltage branch 18, and, through the other of its ends, to a secondary voltage reference.
For example, and as illustrated in
Advantageously, the DC-DC converter further comprises an auxiliary branch 50 and an auxiliary winding 52.
The auxiliary branch 50 extends between two connection terminals 54, and comprises two sub-branches 55 in series connected to each other at a middle point 57. Each sub-branch 55 of the auxiliary branch 50 is similar to the sub-branches 34 of the low voltage branch 16 or the high voltage branch 18.
The auxiliary winding 52 is magnetically coupled to the primary winding 44 of the transformer 24. Further, the auxiliary winding 52 is connected, through one of its ends, to the middle point 57 of the auxiliary branch 50, and, through the other of its ends, to an auxiliary voltage reference.
For example, and as illustrated by
As illustrated in
The AC-DC converter 14 includes N connection points 58, each connection point being connected to a corresponding switch 60.
Each switch 60 is able to be controlled to connect a connection point 58 of the AC-DC converter 14 to a corresponding phase of the motor 8 or the distribution system 10.
Further, the AC-DC converter 14 is connected to the DC-DC converter at the first high voltage terminal 30 and the second high voltage terminal 32.
The AC-DC converter 14 has a known architecture allowing an operation as an inverter, a rectifier or an H-bridge.
The controller 15 is configured to drive the ON or OFF state of the first switch 20, the second switch 22 and of each switching module 38.
The controller 15 is further configured to drive the AC-DC converter to operate the AC-DC converter as an inverter, a rectifier or an H-bridge.
The operation of the electrification line 2 will now be described.
During a pulling phase, during which energy should be transferred from the battery 6 to the electric motor 8, the controller 15 controls the switches 60 to connect each connection point 58 of the AC-DC converter 14 to a corresponding phase 62 of the electric motor 8.
The controller 15 also controls the first switch 20 and the second switch 22 such that they are in an OFF state.
Further, the controller 15 drives the switching modules 38 of the DC-DC converter 12 according to a known control law of a boost converter to transfer electric energy from the battery 6 to the high voltage branch 18. The controller 15 also drives the AC-DC converter 14 according to a control law of an inverter known to transfer energy from the high voltage branch 18 to the electric motor 8.
During an energy restoration phase, also called “V2G”, during which electric energy should be transferred from the battery 6 to the distribution system 10, the controller 15 controls the switches 60 to connect each connection point 58 of the AC-DC converter 14 to a corresponding phase 64 of the distribution system 10.
The controller 15 also controls the first switch 20 and the second switch 22 such that they are in an OFF state.
Further, the controller 15 drives the switching modules 38 of the DC-DC converter 12 according to a known control law of a boost converter to transfer electric energy from the battery 6 to the high voltage branch 18. The controller 15 also drives the AC-DC converter 14 according to a control law of an inverter to transfer energy from the high voltage branch 18 to the distribution system 10.
During a quick charging phase, during which energy should be transferred from all the phases 64 of the distribution system 10 to the battery 6 to charge the battery 6, the controller 15 controls the switches 60 to connect each connection point 58 of the AC-DC converter 14 to a corresponding phase 64 of the distribution system 10.
The controller 15 also controls the first switch 20 and the second switch 22 such that they are in an OFF state.
Further, the controller 15 drives the AC-DC converter 12 according to a known control law of a rectifier to transfer energy from the distribution system 10 to the high voltage branch 18. The controller 15 also drives the switching modules 38 of the DC-DC converter 12 according to a known control law of a buck converter to transfer electric energy from the high voltage branch 18 to the battery 6.
During a slow charging phase, during which energy should be transferred from two phases 64 of the distribution system 10 to the battery 6 to charge the battery 6, the controller 15 controls the switches 60 to connect said two phases 64 to the corresponding connection point 58 of the AC-DC converter 14, called “active connection point”. The other connection points 58 of the AC-DC converter 14 are not connected.
The controller 15 also controls the first switch 20 and the second switch 22 such that they are in an ON state, such that the transformer 24 is bypassed, that is off-circuit.
Further, the controller 15 drives the AC-DC converter 12 according to a known control law of an H-bridge to transfer energy from the distribution system to the battery 6.
During an auxiliary charging phase, during which electric energy should be transferred from the battery 6 to the accumulator 56, the controller 15 controls the first switch 20 and the second switch 22 such that they are in an OFF state.
Further, the controller 15 drives the switching modules 38 of the DC-DC converter 12 and the auxiliary branch 50 according to a known control law of a buck converter to transfer electric energy from the battery 6 to the accumulator 56.
| Number | Date | Country | Kind |
|---|---|---|---|
| 16 58931 | Sep 2016 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2017/052553 | 9/22/2017 | WO | 00 |
