WO2009074604A1

WO2009074604A1 - Device for controlling a dc-dc converter and hybrid vehicle fitted therewith

Info

Publication number: WO2009074604A1
Application number: PCT/EP2008/067219
Authority: WO
Inventors: Delphine Hamel; Christophe Le Vaillant; Abdelmalek Maloum
Original assignee: Renault S.A.S.
Priority date: 2007-12-13
Filing date: 2008-12-10
Publication date: 2009-06-18
Also published as: FR2925242B1; FR2925242A1

Abstract

The invention relates to a device for controlling a DC-DC converter, the converter comprising a conductor for connecting to a battery, an inductive part connected between the conductor and the mid-point of a switching bridge with the switches connected in series to the terminals of a capacitive part, the control device comprising a unit for calculating parameters for controlling the opening and closing of the switches. According to the invention, the device comprises: means (23, 25) for determining a setpoint value (I_REF) for an electrical parameter representative of the charging and discharging of the battery and for determining an actual value (I_MES) of this parameter, a proportional and integral controller (28) working on the difference between the values (I_REF, I_MES) to form a parameter (V_REG) used for regulating, a means (31) of calculating an anticipation parameter (V_ANT) according to a predetermined increasing function of the setpoint value (I_REF), means (33) of calculating a regulating parameter (U_SELF) by addition of the parameter (V_ANT) to the parameter (V_REG), means of calculating control parameters as a function at least of the second regulating parameter (U_SELF).

Description

DEVICE FOR CONTROLLING CONTINUOUS-CONTINUOUS CONVERTER AND HYBRID VEHICLE PROVIDED THEREWITH

The invention relates to a control device of a DC-DC converter. One field of application of the invention is the voltage conversion between a battery and an energy storage capacity. This converter is used for example in a hybrid motor vehicle that is to say having both a heat engine and one or more electrical machines for its propulsion. The role of the converter is twofold: it charges the capacity to the nominal voltage of the electrical machines and then allows the transfer of power between the battery and the electrical machines in both directions. Power is transferred from the battery to the electrical machines via the storage capacity and the converter during the start-up or acceleration phases, for example. Conversely, the power transfer is electrical machines to the battery through the storage capacity and the converter, when stopping or braking the vehicle, to recharge the batteries.

The control device must ensure that a reference power, having an imposed setpoint, can be transferred by the converter of the battery or batteries to the capacitive part or the capacitive part to the battery or batteries. Thus, the control strategy of the converter must adapt to the constraints of its environment of use, for example in a hybrid vehicle.

In particular, the control strategy must adapt as much as possible in real time to the power demands imposed on it by its environment of use. In a known manner, the DC-DC converter comprises an inductive portion connected to the battery, which makes it possible to store electrical energy, and switches, for example formed of IGBT-diode modules, for connecting the capacitive portion to the inductive part.

One of the requirements of the control strategy is speed. Indeed, the response time of the DC-DC converter must be low to respond correctly to the power demands, such as that coming from the person driving the vehicle when it controls the start or accelerations thereof.

Another requirement of the control strategy is accuracy. The response of the DC-DC converter must indeed be precise in order to avoid over-consumption of electricity and jolts. In particular, we seek to minimize service defects.

The aim of the invention is to provide a control device for a DC-DC converter meeting these requirements. For this purpose, a first object of the invention is a control device for a DC-DC converter, the converter comprising a connection conductor to a battery for energy storage able to be charged and discharged in DC voltage, a inductive portion connected between the connecting conductor and the midpoint of a switch bridge connected in series across a capacitive portion of energy storage, able to be charged and discharged in DC voltage, the switches of the bridge being each capable of being controlled by an opening and closing control variable, the control device comprising a unit for calculating the control quantities for opening and closing of the switches, characterized in that the control device comprises: means for determining a first setpoint value of at least one electrical quantity representative of the charge and the discharge of the battery, and one or more x true value of said electrical quantity representative of the charge and the discharge of the battery, a proportional and integral proportional regulator on the difference between the first and second values to form a first regulation quantity, used to calculate the quantities of opening and closing control of the switches, a first means of calculating a magnitude of anticipation according to a first predetermined increasing function of the first set value of the battery and of the same sign as the latter, second means of calculating a second manipulated variable by adding the anticipation quantity to the first control variable, third means for calculating the control quantities for opening and closing the switches as a function of at least the second control variable.

According to embodiments of the invention:

- The first predetermined increasing function is a multiplication of the first setpoint quantity by a first prescribed multiplicative coefficient, positive and non-zero. - The device further comprises a means of calculating an output return magnitude according to a second predetermined increasing function of the second real value of the battery and of the same sign as the latter, the second means of calculation calculating the second control variable by adding the anticipation quantity and subtracting the output return quantity from the first control quantity.

- The second predetermined increasing function is a multiplication of the second real value of the battery by a second multiplicative coefficient prescribed, positive and non-zero.

Said electrical quantity representative of the charge and the discharge of the battery is its current or its power.

The first control variable, the anticipation quantity and the second control variable correspond to voltages, the determination means comprise means for determining a first real voltage of the battery and means for determining a second voltage. of the capacitive part, the control quantities of the switches are their respective opening and closing cyclical ratios, the calculation unit comprising means for calculating the respective cyclic opening and closing ratios of the switches, at least using dividing the sum of the second control variable and the first battery voltage by the second voltage of the capacitive portion.

- The means for determining the second real value of the battery comprises a current sensor flowing in the inductive portion of the converter.

The determination means comprise a means for determining a first real voltage of the battery, a means for determining a target power of the battery and a calculating means, as the first set value of the battery, the current; setpoint of the battery by dividing the target power by the first voltage of the battery.

A second object of the invention is a motor vehicle with a hybrid transmission for driving the driving wheels of the vehicle, comprising a kinematic chain driving the drive wheels, adapted to be coupled to either at least one electric machine or a thermal engine, the electrical machine being connected to a capacitive energy storage part, connected to at least one energy storage battery via a DC-DC converter, the battery and the capacitive part being adapted to be loaded and unloaded, characterized in that it comprises a control device of the DC-DC converter as described above. The invention will be better understood on reading the description which follows, given solely by way of non-limiting example with reference to the accompanying drawings, in which: FIG. 1 is a modular block diagram of a hybrid vehicle, in which a DC-DC converter controlled by the device according to the invention is used, FIG. 2 is a modular block diagram of the DC-DC converter according to FIG. 1,

FIG. 3 is a modular block diagram of a control device of the DC-DC converter in an embodiment according to the invention,

FIG. 4 is a modular block diagram of a corrector present in the control device according to FIG. 3, and FIG. 5 is a modular block diagram of a regulator present in the control device according to FIGS. 3 and 4.

In the following, the DC-DC converter and its control device are described in the case of a vehicle with a hybrid transmission, that is to say providing the coupling of a heat engine and a or several electrical machines. Of course, the converter can be used in other environments than a vehicle.

In FIG. 1, the DC-DC converter 1 is connected between a battery 2 for storing electrical energy and a capacitive part 3 for storing electrical energy and ensures the conversion in both directions between the DC voltage of the battery 2 and the DC voltage of the capacitive portion 3. For battery 2 is meant one or more batteries connected to each other, such as for example energy modules, as is known. The battery 2 is also called a battery pack and can actually comprise several batteries, the reference 23 thus designating the battery or batteries. The capacitive portion 3 is connected to first and second electrical machines 4, 5 and serves as a buffer capacity for maintaining a constant voltage across the electrical machines 4, 5 to use at their nominal voltage. The electrical machines 4, 5 are connected to a kinematic chain 6 for driving the drive wheels 7 of the motor vehicle. The mechanical part 8 of the motor vehicle also comprises, in addition to the driveline 6 and the wheels 7, a heat engine 9, such as for example an internal combustion engine, also capable of being coupled to the driveline 6 for driving the engines. 7-wheel drive, as is known.

The DC-DC converter 1 (DCDC) has two phases in its general operation. The first phase consists in charging the capacitive part 3. In the initial conditions, at the start of the car, the voltage at the terminals of the battery 2 is equal to the voltage at the terminals of the capacitive part 3. A power setpoint is then given to converter 1 so that it loads the part capacitive 3 until the voltage of the capacitive portion 3 has reached the reference voltage, equal to the nominal voltage of the electrical machines 4, 5. The battery 2 is thus discharged in order to charge the capacitive portion 3. Then the machines Electrical 4, 5 and the heat engine 9 take over to provide enough energy to keep the capacitive portion 3 charged and therefore its fixed voltage.

Once this first step is performed, the DC-DC converter 1 enters a normal operating phase. From the fixed voltage of the capacitive part 3, the DC-DC converter 1 provides power by discharging the battery 2 when the vehicle needs it, for example in the starting phases of the heat engine 9 and in the phases of operation. 'acceleration. From the fixed voltage of the capacitive part 3, the DC-DC converter 1 recovers power and recharges the battery 2 during the braking or stopping phases.

In FIG. 2, the DC-DC converter 1 comprises an inductive part 11 making it possible to store electrical energy and a bridge 12 of switches 14, 15 connecting to the capacitive part 3. The inductive part 11 comprises one or more inductance coils for storing energy. The switches 12 are for example each formed of an IGBT-diode module, which allows the current to pass or which blocks it.

The inductive part 11 is connected on the one hand to the battery 2 by a conductor 1 the link and secondly to the midpoint 13 of the bridge 12 between the first switch 14 and the second switch 15. The series circuit of the battery 2 and the inductive portion 11 is connected in parallel with the first switch 14, while the series circuit of the first switch 14 and the second switch 15 is connected in parallel with the capacitive portion 3. The switches 14, 15 each comprise at least a command entry to open or close them. As regards the first switch 14, the control input makes it possible to control the voltage Ui ₄ at its terminals:

- If the switch 14 is open, Ui ₄ = U_CAPA, where U_CAPA indicates the voltage across the capacitive portion 3, - if the switch 14 is closed, Ui ₄ = 0.

When the switch 14 is open, the switch 15 must be closed and when the switch 14 is closed, the switch 15 must be open. On average, Ui ₄ = α. U_CAPA, with α = opening time / cycle time, that is to say the cyclic ratio of opening and closing of the switch 14. The duty cycle α allows to control the opening and closing switch 14. The other switch 15 is controlled with a cyclic ratio of opening and closing complementary β = 1 - α. Of course, the control variables of the switches 14, 15 could be other than their respective duty cycles.

The control device comprises: a means 21 for supplying the value of the reference power P REF, which is the reference power to be transferred from the battery 2 to the capacitive part

3 or the capacitive portion 3 to the battery 2, a means 22 for determining the value of the real voltage U BAT of the battery 2, a means 23 for determining the value of the real current I MES of the battery 2, as the second value real of an electrical quantity representative of the charge and of the discharge of the battery, a means 24 for determining the value of the real voltage U CAPA of the capacitive part 3.

These means 21, 22, 23, 24 of determination are for example formed by measuring means. The means 23 for determining the current of the battery 2 is for example a means measuring the current flowing in the inductive portion 11 and is for example formed by a sensor thereon.

We have P REF = U BAT. I BAT, with I BAT positive or negative depending on charging or discharging the battery. The control device comprises a module 25 for calculating the value of a reference current I REF connected to the means 21 and 22 for dividing the value of the reference power P REF by the value of the voltage U BAT according to the formula I REF = P REF / UB AT. The current I REF forms the first reference value of the electrical quantity representative of the charge and the discharge of the battery of the battery. This electrical quantity representative of the charge and the discharge of the battery of the battery could also be formed by the power of the battery.

A means 26 is provided for calculating the control quantities of the switches 14, 15, formed in the embodiment described by the cyclic opening and closing ratios α and β. The calculating means 26 comprises, for example, a corrector 26 acting on the control variables of the switches 14,

15 to regulate the current I MES of the battery so as to make it equal to the reference current I REF forming a current setpoint quantity for the battery 2, as shown in FIG. 3. For this purpose, the corrector 26 comprises a module 27 for forming the distance ε between the value of the reference current I REF and the value of the current I MES of the battery 2, according to the formula: ε = I REF - I MES. The corrector 26 also comprises a proportional and integral proportional regulator module 28 on the current gap ε between the reference current I REF and the current I MES of the battery 2 to form on its output 29 a first value

V REG regulation voltage, as shown in Figure 5, as the first control variable.

The control quantities of the switches 14, 15 are formed from this first regulation V REG variable.

As is shown in FIGS. 4 and 5, the regulator 30 of the corrector 26 comprises, in addition to the proportional and integral proportional regulator module 28, a module 31 with anticipatory action on the value of the reference current I REF. that is, the reference quantity of the converter 1. This anticipatory module 31 generates a magnitude V ANT of anticipation on its output 32 according to a first predetermined increasing function of the reference current I REF. This first increasing function retains the sign of the magnitude I REF of input setpoint. This first function is for example the multiplication by a constant multiplicative factor, here homogeneous with an impedance, according to the formula V ANT = A.

I REF.

For example, A> 0.

In the embodiment shown in the figures, the magnitude V ANT of anticipation corresponds to a voltage.

The V ANT anticipation value is added to the control V REG value by a module 32 receiving the outputs 29 and 32 on its two adders inputs.

In the embodiment shown in FIG. 5, the regulator 30 of the control device also comprises, in addition to the proportional and integral proportional regulator module 28, an output return module 33 on the value of the current

I MES battery to mitigate too large voltage increases due to the addition of anticipatory magnitude V ANT.

The output return module 34 generates on its output 35 from the current I MES of the battery a V RET output return. The height

V RET return output is generated for example according to a second predetermined increasing function of the current I MES of the battery 2 and retains the same sign as this current I MES. For example, the second function of calculating the output return magnitude multiplies the current I MES of the battery 2 by a constant multiplicative coefficient B, here homogeneous with an impedance, according to the formula V RET =

B.I MES.

For example, B> 0. In the embodiment shown in the figures, the V RET of output return corresponds to a voltage.

The module 33 subtracts from the regulation variable V REG and from the anticipative variable V ANT the output feedback V RET by being connected by its subtracting input to the output 35, to generate on its output 36 a control variable U SELF according to the formula :

U SELF = V REG + V ANT - V RET

In the embodiment shown in the figures, this manipulated variable is a voltage value. In the embodiment shown in the figures, the control variable U SELF voltage corresponds to a voltage of the inductive portion 11.

Of course, the V RET output return size and the output return module 34 could be omitted.

As shown in FIG. 4, the control variable U_SELF is added to the value of the voltage U B AT of the battery 2 by an adder module

37, of which an adding input is connected to the output 36 and of which another adding input 38 is connected to the means 22 for determining the voltage UB AT of the battery 2. The adder module 37 supplies at its output 39 a U COM value of control voltage equal to the sum of the control variable U SELF and the value of the voltage U BAT of the battery 2 according to the formula:

U COM = U SELF + U BAT

The control voltage U COM value is divided by the value of the voltage U CAPA of the capacitive part 3 by a divider module 40 receiving on its multiplier input the output 39 and on its divider input 41 the voltage value AP AP A of the capacitive part provided by the means 24, to provide on its output 42 the duty cycle α opening and closing of the first switch 14, according to the formula α = U COM / U CAPA.

The duty cycle β controlling the second switch 15 is also calculated according to the above. The opening and closing cyclic ratios α and β of the switches 14 and 15 are sent as a control variable to a circuit 43 actuator switches 14 and 15, to open and close correspondingly by acting on their input control.

Of course, any means of calculation other than the means 37 and 40 could be used to calculate in a general way the control variables from the manipulating variable, this manipulating variable, as well as the magnitude of regulation, the anticipation quantity and the output return magnitude may be a voltage or other than a voltage.

Claims

1. Control device of a DC-DC converter, the converter (1) comprising a conductor (l ia) for connection to a battery (2) for energy storage able to be charged and discharged in DC voltage, a part inductive circuit (11) connected between the connecting conductor (1 la) and the midpoint (13) of a switch bridge (14, 15) connected in series across a capacitive capacitor (3) energy, able to be charged and discharged in DC voltage, the switches (14, 15) of the bridge being able to be each controlled by a magnitude (α, β) of opening and closing control, the control device comprising a unit for calculating the values (α, β) for opening and closing control of the switches (14, 15), characterized in that the control device comprises: means (21, 23, 25) for determining a first set value (I REF) of at least one electrical quantity representative of the rge and battery discharge, and a second real value (I MES) of said electrical quantity representative of the charge and discharge of the battery, - a regulator (28) proportional and integral action on the the difference between the first and second values (I REF, I MES) to form a first control variable (V REG), used to calculate the opening and closing control quantities (α, β) of the switches (14, 15); ), a first means (31) for calculating a magnitude (V ANT) of anticipation according to a first predetermined increasing function of the first reference value (I REF) of the battery and of the same sign as the latter, second means (33) for calculating a second manipulated variable (U SELF) by adding the anticipation quantity (V ANT) to the first regulation quantity (V REG), - third means (26) for calculating the quantities (α, β) for controlling the opening and closing of the switches (14, 1 5) according to at least the second control variable (U SELF).

2. Device according to claim 1, characterized in that the first predetermined increasing function is a multiplication of the first magnitude (I ERF) setpoint by a first prescribed multiplicative coefficient (A), positive and non-zero.

3. Device according to any one of the preceding claims, characterized in that it further comprises means (34) for calculating an output return magnitude (V RET) according to a second predetermined increasing function of the second value. (I_MES) of the battery and of the same sign as this one, the second calculating means (33) calculating the second control variable (U SELF) by adding the magnitude (V ANT) of anticipation and subtraction of the output return variable to the first control variable (V REG).

4. Device according to claim 3, characterized in that the second predetermined increasing function is a multiplication of the second real value (I MES) of the battery by a second prescribed multiplicative coefficient (B), positive and non-zero.

5. Device according to any one of the preceding claims, characterized in that said electrical quantity representative of the charging and discharging of the battery is its current (I REF) or its power (P REF).

6. Device according to any one of the preceding claims, characterized in that the first control variable, the magnitude (V_ANT) of anticipation and the second control variable (U SELF) correspond to voltages, the means (21, 22 , 23, 24, 25) comprise means (22) for determining a first real voltage (UB AT) of the battery and means (24) for determining a second real voltage (U CAP A) of the capacitive part (3), the control variables of the switches (14, 15) are their respective opening and closing cyclic ratios (α, β), the calculation unit comprising means (37, 40) for calculating the respective cyclic ratios (α, β) of opening and closing of the switches (14, 15) at least by using a division of the sum of the second control variable (U SELF) and the first voltage (U BAT) of the battery by the second voltage (U CAP A) of the capacitive part.

7. Device according to any one of the preceding claims, characterized in that the means (23) for determining the second real value (I MES) of the battery comprises a sensor (23) of the current (I MES) flowing in the inductive part (11) of the converter.

8. Device according to any one of the preceding claims, characterized in that the means (21, 22, 23, 24, 25) for determining comprises means (22) for determining a first real voltage (U BAT) of the battery, a means (21) for determining a power (P REF) of the battery set point (2) and a means (25) for calculating, as the first setpoint value (I REF) of the battery, the current (I REF) of the setpoint of the battery (2) by division of the power (P REF) setpoint by the first voltage (UBAT) of the battery (2).

9. Motor vehicle with hybrid transmission for driving the driving wheels (7) of the vehicle, comprising a kinematic chain (6) driving the driving wheels, capable of being coupled to at least one electric machine (4, 5) , or to a heat engine (9), the electric machine (4, 5) being connected to a part capacitive (3) energy storage device, connected to at least one battery (2) for storing energy via a DC-DC converter (1), the battery (2) and the capacitive part (3). ) being able to be loaded and unloaded, characterized in that it comprises a control device of the converter (1) DC-continuous according to any one of the preceding claims.