EP2707241A2

EP2707241A2 - Device and method for managing the electric braking of a vehicle

Info

Publication number: EP2707241A2
Application number: EP12719399.3A
Authority: EP
Inventors: Ivan MODOLO
Original assignee: Michelin Recherche et Technique SA Switzerland; Compagnie Generale des Etablissements Michelin SCA; Michelin Recherche et Technique SA France
Current assignee: Michelin Recherche et Technique SA Switzerland; Compagnie Generale des Etablissements Michelin SCA; Michelin Recherche et Technique SA France
Priority date: 2011-05-13
Filing date: 2012-05-09
Publication date: 2014-03-19
Also published as: WO2012156252A3; WO2012156252A2; US20140084820A1; US9190939B2; FR2975243B1; KR20140023346A; JP2014517666A; CN103534129B; FR2975243A1; CN103534129A

Abstract

The invention relates to a device for managing electric braking power (1), which device comprises a continuous bus (10), said continuous bus including: a connection pole (12) connecting to an electric traction machine (21) of a vehicle, said machine being associated with an inverter (20) which, in braking mode, delivers an electric braking power over the continuous bus; a connection pole (13) connecting to an electric power storage battery (30); a dissipation branch (1D) connected at a connection point (11) to the continuous bus, said branch including an electronic dissipation switch (1D1) connected in series with a dissipation resistor (1D2); a current collector (15) on the continuous bus, disposed between the connection point (11) of the continuous bus and the connection pole (13) connecting to a battery; and a controller (18). The device also includes an electronic charge switch (1C1) between the connection point at which the dissipation branch (1D) is connected to the continuous bus (10) and the connection pole connecting to a battery of the continuous bus, said switch controlling the flow of current over the continuous bus from the connection pole connecting to the electric machine to the connection pole connecting to a battery. The controller calculates: the power that can be absorbed by the charge of the battery (30), the power that can be dissipated by the dissipation resistor (1D2), and the power sent over the continuous bus (10) and, when the power sent over the continuous bus (10) is greater than the cumulative power that can be absorbed by the charge of the battery (30) and the dissipation in the dissipation resistor (1D2), said controller (18) opens the electronic charge switch (1C1).

Description

DEVICE AND METHOD OF MANAGEMENT

ELECTRIC BRAKING OF A VEHICLE

FIELD OF THE INVENTION

The present invention relates to road vehicles. It relates in particular to the braking systems of a road vehicle with electric traction. More particularly, it relates to the management of electric braking power.

STATE OF THE ART

Electric vehicles include vehicles in which the electrical energy necessary for their movement is stored in batteries and vehicles in which the electrical energy is produced on board at least in part, for example by a heat engine driving a motor. generator or by a fuel cell. In electric vehicles, even if the braking of the vehicle is provided by a conventional friction mechanical braking system, one of the interests of electric vehicles comes from their ability to recover in electrical form and store part of the vehicle. energy generated during braking.

Indeed, an electric machine being reversible, it can be used as a motor and also as an electric generator during the braking phases of the vehicle and in this case it converts the mechanical braking energy into electrical energy that the vehicle must absorb , preferably by storing it to save the energy needed to use a vehicle, and inevitably by dissipating it when it is not or no longer possible to store it. This mode of operation is often called "electric braking" or "regenerative braking" even when, in fact, the electrical energy obtained by operating the electric machine or machines is finally dissipated thermally at least partially.

As an illustration of the state of the art, one can quote the patent application US 2003/0088343 which describes an electric power train for a hybrid motor vehicle equipped with an internal combustion engine and a electric machine that intervenes in assistance for the motorization of the vehicle. The electric machine is itself powered by a battery. More particularly for the electric braking aspect, mention may be made of the patent application WO 2008/000636 which describes an electric braking mode, in particular which evokes a strategy for the management of electrical energy programmed in an electronic recovery module, this one distributing the braking energy so as to recharge a bank of super capacitors and / or to dissipate the energy in an electrical dissipation resistor. This document adds that the power of the electrical energy storage means, in this case, super capacitors, can be limited, and that beyond the braking level that this power allows, the electric power produced by the electrical traction machine must then be directed to the dissipation means. This document, which focuses on the organization of redundancy to achieve a high degree of reliability of a purely electric braking, does not give details on the management of the recharge of the means of storing electrical energy.

The objective of the present invention is to provide the means to ensure a powerful electric braking, by dissipation of the electrical energy produced by an electric machine operating in generator mode, which is optimal and independent of the state of charging means for storing electrical energy, all also offering and preferably means to ensure optimum charging of a means of storing electrical energy while ensuring.

BRIEF DESCRIPTION OF THE INVENTION

The invention proposes a braking power management device comprising a continuous bus, said continuous bus comprising:

A pole for connection to an electric traction machine of a vehicle, the machine being associated with an inverter, the inverter delivering, in braking mode, on the DC bus, an electric braking power,

A connection pole to an electric energy storage battery,

the device comprising:

A dissipation branch connected to a point of connection to the continuous bus, said branch comprising a dissipation resistor,

Between the point of connection of the dissipation branch to the DC bus and the connection pole to a battery of the DC bus, an electronic load switch,

A current sensor on the DC bus disposed between the connection point of the DC bus and the connection pole to a battery,

• a controller receiving:

o a measurement of the voltage "U" on the DC bus,

o "Battery charging current limit" information,

a measurement of the current on the DC bus delivered by the current sensor on the DC bus, The controller calculating the power that can be absorbed by the battery charge on the basis of the "U" voltage on the DC bus and the "limit current for recharging the battery", the controller calculating the power that can dissipate the dissipation resistor on the basis of the value thereof and the voltage "U" on the DC bus, the controller calculating the power sent on the DC bus based on the value of the measurement of the current on the DC bus. DC bus delivered by the current sensor and the voltage "U" on the DC bus and, when the power sent on the DC bus is greater than the total power that can absorb the battery charge and the dissipation in the resistance of the dissipation, the controller opens the electronic load switch.

The invention also extends to a method of managing the electric braking mode of a vehicle comprising an electric traction machine of said vehicle, comprising an electric circuit connecting said electric machine to an electric energy storage battery and to an electrical energy dissipation resistor, wherein when the electrical braking power is greater than the sum of the charging power of the battery and the dissipating power in the electrical energy dissipating resistor, the battery is disconnected so as to allow an increase of the voltage of the electrical circuit connecting said electric machine to the dissipation resistor.

BRIEF DESCRIPTION OF THE FIGURE

The following description makes it easy to understand all aspects of the invention by means of Figure 1 which illustrates a device according to the invention.

DESCRIPTION OF BEST EMBODIMENTS OF THE INVENTION

In Figure 1, we see a power management device braking 1 connected on the one hand to an inverter 20 supplying an electric machine 21 for traction of a vehicle and on the other hand to a battery 30 electrical energy storage. A central global vehicle management unit 4 provides general vehicle supervision and dialogue with the management device of the vehicle. electrical power braking 1 as will be explained later. The battery 30 comprises a battery management system 31. The braking power management device 1 comprises a continuous bus 10 which shows the positive line 10+ and the negative line 10-. The braking power management device 1 comprises a first connection pole 12 to the inverter 20, and a second connection pole 13 to the battery 30. The braking power management device 1 comprises a branch of dissipation 1D connected to a connection point 11 of the dissipation branch 1D to the DC bus 10, in parallel with the inverter 20 supplying the electric traction machine 21. This 1D dissipation branch comprising an electronic dissipation switch 1D1, consisting of an IGBT type transistor (Insulated Gate Bipolar Transistor), connected in series with a dissipation resistor 1D2. We still see a diode 1D3, associated by construction of an IGBT type transistor, and a diode 1D4 which, during the opening of the electronic dissipation switch 1D1, allows the current flowing in the dissipation resistor 1D2 of cancel. This is all the more useful as this circuit is inductive. Note that the electronic dissipation switch 1D1 could be another type of semiconductor, for example a MOS transistor (Metal Oxide Semiconductor), the choice being made by those skilled in the art according to the practical details of construction.

The braking power management device 1 comprises an electronic load switch ICI disposed between the connection point 11 of the dissipation branch 1D to the DC bus 10 and the second connection pole 13 to a bus battery. continued. Said electronic charge switch is advantageously a transistor, as indicated above for the electronic dissipation switch 1D1. The electronic load switch IC1 controls the flow of current on the DC bus 10 from the first connection pole 12 to the second connection pole 13 to a battery. The term "controlling the flow of current" means that the current is regulated as will be explained below.

The braking power management device 1 comprises a current sensor 15 on the DC bus 10, arranged between the electronic load switch ICI and the second connection pole 13. In practice, preferably, the current sensor 15 must be as close as possible to battery 30 because there are (or may be) other consumers connected to the DC bus 10, upstream of the electronic load switch ICI, and the current sensor It monitors the battery current both in charging and discharging.

The device for managing the electric power in braking 1 also comprises, mounted in parallel with the electronic load switch ICI, a diode 1C2 allowing the flow of current on the DC bus 10 from the second connection pole 13 to the first connection pole 12. Capacitors 16 and 17 are connected to the DC bus 10, on either side of the electronic load switch ICI, to smooth the voltage on the DC bus 10 during the closing or opening the electronic load switch ICI and, respectively, the electronic dissipation switch 1D1.

A controller 18 provides control of the electric power management device in braking 1. It is seen that it receives from the battery management system 31, via a CAN bus 180, various information useful for managing the power. braking power, including a setpoint of "charging current of the battery" Ic recharge max, a measurement of the current on the DC bus 10 delivered by the current sensor 15, via a line 150, a measurement of the voltage "U On the DC bus 10, between the electronic load switch ICI and the second connection pole 13, via a line 160, a measurement of the voltage on the DC bus 10, between the electronic load switch ICI and the first connection pole 12, via a line 170, and various information coming from the central management unit of the vehicle 4 via a CAN® bus 181. The braking torque is managed by the global central management unit of the vehicle 4 which , according to the the wishes of the driver of the vehicle, sends a CAN® bus 180 to the inverter 20 a set torque. The inverter 20, up to the maximum allowable current (this maximum allowable current is determined by the controller 18) on the DC bus 10, controls the electric machine 21 so as to develop this torque. Finally, the controller 18 carries out the control of the electronic dissipation switch 1D1 and the electronic load switch IC1 by sending the appropriate electrical signals on the line of the dissipation control line 110 and on the charge control line 120 , respectively. In this way, the controller 18 ensures the management of the power flow which raises the traction chain and the needle in the right place.

Let's go to the operation of the device for managing the electrical power during braking 1.

Let's start with the assumption that the power sent on the DC bus 10 is greater than the total power that can absorb the load of the battery 30, and the dissipation in the resistive resistor 1D2 when ICI is closed. In this case, or when the charge of the battery 30 is total, the device for managing the electrical power during braking 1 operates in "maximum dissipation mode", operation during which the electronic load switch ICI is permanently open and the 1D1 electronic dissipation switch is permanently closed (duty cycle 100%). There is no recovery of electrical energy by charging the battery 30. The "U" voltage of the DC bus 10 will increase and stabilize so as to balance the dissipation power in the dissipation resistor 1D2 to that produced. by the electric traction machine or machines 21 sending electric energy to the DC bus 10. If the power produced by the electric traction machine or machines 21 increases, the bus voltage increases, and vice versa. Let us consider another hypothesis where the power produced by the electrical traction machine or machines 21 drops sufficiently, to the point of being less than the power that can be absorbed by the battery 30 and the dissipation resistor 1D2. In this case, the device for managing the electrical power during braking 1 operates in maximum charge mode. The ICI electronic load switch closes and the control controlled by the controller 18 regulates the duty cycle of the electronic dissipation switch 1D1 so as to slave the charging current to the maximum allowed by the management system. battery 31.

The optimal charging of an electrochemical battery, according to the technology thereof, can be done by a constant current, within the limit of a value Ic recharge max. For example, Lithium Polymer batteries or Lithium Ion batteries accept fairly large charging currents, but less than the discharge currents. The determination of the setpoint values for the maximum charge (ie the charging limit current of the battery) depends on the technology of the electric accumulator used, possibly other parameters such as the temperature, the state of charge, the conditions of vehicles, all things outside the scope of the present invention. Said charging current limit of the battery is a parameter that the present invention operates cleverly.

Preferably, the controller 18 comprises a comparator evaluating the difference between the charging limit current of the battery and the current on the DC bus, the controller comprising a unit ensuring the control of the electronic dissipation switch so as to leaving said electronic load switch closed for as long as the current on the DC bus is less than the charging limit current of the battery and so as to drive said electronic dissipation switch in a cycle maintaining the charging current of the battery equal to the limiting current recharging the battery when the current on the DC bus is not lower than the charging limit current of the battery.

Thus, the control of the dissipation power, that is to say the part of the power produced by the electric machine 21 which can not be used to charge the battery 30, is done by a duty cycle. suitable opening and closing of the electronic dissipation switch 1D1; the time during which the electronic dissipation switch 1D1 is open varies as a function of the difference between the maximum current charging current of the battery and the measurement of the current by the current sensor 15. By convention, it is called "mode maximum load "an operation of the device for managing the electric power during braking 1 during which the electronic load switch ICI is permanently closed.

In maximum load mode, the power returned on the DC bus 10 (by the inverter or 20 traction machines 21) is necessarily lower than the power that can absorb the battery 30 and the dissipation resistor 1D2 when 1D1 is closed. In this operating mode, the voltage applied across the dissipation resistor 1D2 is equal to that battery (neglecting voltage drops in semiconductors and power lines). The servo control the duty cycle of the electronic dissipation switch 1D1 so that the charging current of the battery 30 is at the maximum allowed by the latter. The more the power produced by the one or more traction machines 21 increases, or the lower the charge power of the battery 30, the more the duty cycle of the electronic dissipation switch 1D1 increases so as to reduce the power directed towards the battery.

When a predefined voltage value characteristic of a maximum load is reached, it goes to a final phase of the load by keeping the voltage of the battery 30 constant. In this phase, the charging current is monitored. gradually decreasing. When this current falls below a given value (for example, Ic_recharge_max / 20), the battery is considered fully charged.

At the level of the battery 30 itself, the management of its charge is controlled by the battery management system 31. It is this battery management system 31 which, depending on the voltage of the battery, of its temperature, determines said maximum recharge current Ic recharge max. This maximum charging current Ic recharge max is the setpoint sent on the CAN® bus 180. The device for managing the braking power 1 operates so as not to exceed this current. In fact, in a first phase where the predefined voltage of the battery is not reached, the battery management system 31 gives, on the CAN® bus 180 as the maximum recharge the limit given by the battery manufacturer. In a second phase, when the predefined voltage of the battery is reached, the battery management system 31 calculates and sends on the bus CAN 180 a recharging current Ic recharge that achieves this preset voltage. As the battery 30 charges, this charging current Ic decreases.

Preferably, it is necessary to store a maximum of energy in the battery 30 and, this being accomplished, advantageously, a maximum of electrical braking energy is dissipated in the dissipation resistor 1D2 to minimize (or cancel) the recourse mechanical friction braking, to the benefit of the wear of brake pads and discs.

In practice, the controller 18 contains the means for calculating in real time the maximum possible dissipation power and the actual dissipation power, as well as the maximum possible load power and the actual load power, in view of optimal control. One switches from the maximum charging mode to the maximum dissipation mode when the electronic dissipation switch 1D1 is permanently closed. The controller 18 adjusts the dissipation in order to recharge battery to the maximum of what is technologically possible in the actual circumstances of the moment.

In conclusion, we have seen above that, according to the invention, there is provided a method in which when the electrical braking power is greater than the sum of the power of recharging the battery and the dissipation power in the electrical energy dissipation resistor, the battery is disconnected so as to allow an increase in the voltage of the electrical circuit connecting said electrical machine to the dissipation resistor. In addition, preferably, according to the method proposed by the invention, the dissipation current flowing through the dissipation resistor is slaved to the difference between the charging current of the battery and the maximum load current permissible for said battery.

Claims

Braking electric power management device (1) comprising a continuous bus (10), said continuous bus comprising:

A connection pole (12) to an electric traction machine (21) of a vehicle, the machine being associated with an inverter (20), the inverter delivering, in braking mode, on the DC bus, an electric power braking,

A connection pole (13) to a battery (30) for storing electrical energy,

the device comprising:

A dissipation branch (1D) connected at a connection point (11) to the DC bus, said branch comprising a dissipation resistor (1D2),

Between the connection point (11) of the dissipation branch (1D) to the DC bus (10) and the connection pole (13) to a DC bus battery, an electronic charge switch (ICI),

A current sensor (15) on the DC bus arranged between the connection point (11) of the DC bus and the connection pole (13) with a battery,

A controller (18) receiving:

o a measurement of the voltage "U" on the DC bus (10),

o "Battery charging current limit" information,

a measurement of the current on the DC bus delivered by the current sensor (15) on the DC bus,

The controller (18) calculating the power that the battery charge (30) can absorb on the basis of the "U" voltage on the DC bus (10) and the "battery charging limit current" information , The controller calculating the power that the dissipation resistor (1D2) can dissipate on the basis of the value thereof and the voltage "U" on the DC bus (10), the controller calculating the power sent on the continuous bus (10) on the basis of the value of the measurement of the current on the DC bus delivered by the current sensor (15) and the voltage "U" on the DC bus (10) and, when the power sent on the DC bus (10) is greater than the total power that can be absorbed by the battery charge (30) and the dissipation in the dissipation resistor (1D2), the controller (18) opens the electronic charge switch (ICI) . Braking power management device according to claim 1 wherein the dissipation branch (1D) comprises an electronic dissipation switch (1D1) connected in series with said dissipation resistor (1D2),

Braking electric power management device according to claim 2 wherein said electronic dissipation switch is a transistor.

Braking electrical power management device according to claim 1 comprising, mounted in parallel with the electronic load switch, a diode allowing the flow of current on the DC bus from the connection pole to a battery to the connection pole to an electric machine.

Braking electric power management device according to claim 1 wherein said electronic load switch is a transistor.

A method of managing the electric braking mode of a vehicle comprising an electric traction machine of said vehicle, comprising an electric circuit connecting said electric machine to an electric energy storage battery and an electrical energy dissipation resistor, wherein when the electrical braking power is greater than the sum of the recharging power of the battery and the dissipation power in the electrical energy dissipation resistor, the battery is disconnected so as to allow an increase in the voltage of the electrical circuit connecting said electrical machine to the dissipation resistor.

A method of managing the electric braking mode according to claim 5 wherein the dissipation current flowing through the dissipation resistor is slaved to the difference between the charging current of the battery and the maximum permissible load current for said battery.