WO2007009582A1

WO2007009582A1 - Drive train and method for controlling a drive train

Info

Publication number: WO2007009582A1
Application number: PCT/EP2006/006476
Authority: WO
Inventors: Siegfried Saenger Zetina
Original assignee: Daimlerchrysler Ag
Priority date: 2005-07-15
Filing date: 2006-07-04
Publication date: 2007-01-25
Also published as: DE102005033723A1

Abstract

The invention relates to a drive train in addition to a method for controlling a drive train, comprising an internal combustion engine (ICE), a first electromachine (El), a coupling (Cl), a second electromachine (E2), a transmission (G) and at least one driven wheel (W). The internal combustion engine (ICE) is connected to the first electromachine (El) and can be connected to the transmission inlet (GE) by means of the coupling (Cl), the second electromachine (E2) can be connected to the transmission inlet (GE), and the transmission outlet is connected to the at least one driven wheel (W). According to the invention, the torque of the internal combustion engine (Mice), the first electromachine (ME1), the coupling (MC1) and the second electromachine are controlled by a state regulator (ZR) when the coupling is switched. The driving comfort is increased due to said switching of the coupling (Cl).

Description

Powertrain and method for regulating a

drive train

The invention relates to a drive train for a vehicle according to the preamble of claim 1 and a method for controlling a drive train according to the preamble of patent claim 2.

In vehicles with a drive train having an internal combustion engine and at least one electric machine, a so-called hybrid powertrain, can be implemented to drive the vehicle several operating modes.

In a drive train with an internal combustion engine, a first electric machine, a clutch, a second electric machine, a transmission and at least one driven wheel, wherein the internal combustion engine is connected to the first electric machine and is connectable by the clutch to the transmission input, the second electric machine with the transmission input is connected, and the transmission output is connected to the at least one driven wheel, at least operating modes can be realized in which the vehicle is driven purely electrically or purely internal combustion engine. The purely electric ride is characterized by the fact that the vehicle is driven by the second electric machine, while the clutch is open, thus separating the engine and the first electric machine from the rest of the drive train. In the pure combustion engine drive, the vehicle is driven only with the clutch closed by the internal combustion engine, the two electric machines can be operated as a generator.

If you want to switch between these two operating modes, while the vehicle is driven, so close or open the clutch is durchzufuhren such that the clutch is operated as short as possible grinding and thus not too worn and that the ride comfort, for example, by a jerk in the powertrain, not negatively affected.

In known hybrid powertrains, as described for example in DE 199 30 391 A1, the changeover between two operating modes, in which the clutch must be closed, takes place by means of a characteristic map control. A synchronization of the rotational speeds of the output shaft of the internal combustion engine and the transmission input shaft and the engagement of the clutch takes place only by a control based on calibrated desired torque characteristics for the internal combustion engine and connected to the transmission input shaft electric machine. The moment of the electric machine or of the internal combustion engine is reduced or increased in such a way for the smoothest possible switching operation, that the sum of the two moments during this entire Verrampung is equal to the entire torque to be transmitted. The object of the invention is to propose a drive train or a method for controlling a drive train, in which a high ride comfort is achieved when switching the clutch.

According to the invention the object is achieved by the features of claim 1 and of claim 4. Accordingly, when switching the clutch, the moments of the internal combustion engine, the first electric machine, the clutch and the second electric machine are controlled by a state controller.

The present invention considers, on the one hand, the grinding of the coupling as an additional control variable in the system, on the other hand, it coordinates all the moments in a model-based control.

Due to the advantageous control of all torque sources of the drive train, namely the internal combustion engine, the first and second electric machine and the clutch by a state controller, a change between two operating modes in which the clutch must be switched, comfortable, flexible, dynamic and designed according to the driver's wishes become.

In a preferred development, the unmeasured state variables, in particular the load torque and the drive train torsions, are estimated by a state observer. As a result, a measurement of the rotational speeds of the internal combustion engine, the first and second electric machine and the wheel is sufficient.

In a particularly preferred development, the regulation of the drive train is carried out with the aid of a cost function. This has the advantage that according to the weighting of individual factors of the cost function, the control in terms of compliance with the driver's desired torque and / or minimizing slippage and / or minimizing friction work and / or minimizing the jerk and / or efficiency can be optimized.

Furthermore, the additional degrees of freedom can be used while maintaining the desired torque during all phases to a load point shift, in particular between the engine and the first electric machine, which has a positive effect on the efficiency.

Further advantages of the invention will become apparent from the description and the drawings. Concrete embodiments of the invention are shown in simplified form in the drawings and explained in more detail in the following description. Show it

Fig. 1 shows an embodiment of a vehicle with a

2 shows a first model underlying a control according to the invention, FIG. 3 shows a schematic representation of a control circuit according to the invention, and FIG. 4 shows a second simplified model.

In the vehicle shown in Figure 1, the drive train according to the invention has an internal combustion engine ICE, with its output shaft A, a first electric machine El is rotatably connected. In addition, the output shaft A via a clutch Cl with an input shaft GE of a transmission G is connectable. The transmission input shaft GE is connectable via a second clutch KE with a second electric machine E2. The two electric machines El, E2 are electrically connected to a battery B, to from this with electrical energy to be supplied or in regenerative operation to provide them with electrical energy. The output of the transmission G is connected to driven wheels W. It is also possible that only the wheels W of one axle are driven.

In addition to a serial drive, in which the clutch Cl is open, the electric machine El is operated as a generator and the vehicle is driven by the electric motor E2, and a parallel drive, in which the clutch Cl is closed and the internal combustion engine ICE and the two electric machines El , E2 can supply a drive torque, an electric and an internal combustion engine drive can be realized.

In the electric drive, the clutch Cl is opened and the vehicle is driven by the electric machine E2, wherein the internal combustion engine ICE and the rotor of the electric machine El are at a standstill.

During the combustion engine drive, the clutch Cl is closed and the vehicle is driven by the internal combustion engine ICE. The rotor of the electric machine El rotates with the output shaft A of the internal combustion engine ICE and the electric machine El can advantageously be operated as a generator, for example, to operate the internal combustion engine ICE in a different load point and thus with a better efficiency. The rotor of the electric machine E2 rotates with the clutch KE with the transmission input shaft GE and can also be operated as a generator. However, the electric machine E2 can also be decoupled advantageously by the clutch KE from the drive train in order to reduce the electrical idling losses. If it is to be changed from the electric drive into the operating mode of the internal combustion engine drive, triggered for example by a driver request for increased power, for which the power of the electric machine E2 is insufficient or due to a low battery state of charge, it must be closed. This switching operation of the clutch C1 can be subdivided into four phases, which, however, can be quite overlapping.

In phase 1, with the clutch Cl open, the engine ICE is started by the electric machine El, while the vehicle is being driven by the electric machine E2.

After starting, the speed of the internal combustion engine ICE is controlled to that of the electric machine E2 in phase 2. Preferably, the speed of the internal combustion engine ICE is controlled to a value which is about 30 U / min above the speed of the electric machine E2. As a result, the transmitted torque acts accelerating on the driven wheel W. The vehicle is generally accelerated for a short time, which is perceived by the driver as positive.

In phase 3, the transmitted torque M _C i is the clutch Cl regulated up to the complete closure of the clutch Cl, which in this case likewise accordance with the invention the moments of the engine M _lce and the electric machine M _E i, M _E2 are controlled.

If clutch Cl is operated slipping, the torque is transmitted via the frictional force. The transmitted torque M _C i will be so

M _C1 = sgn (<y, -ω _o ) -M _c , where M _{c represents} the maximum transmittable torque. Without slip, the transmitted torque M _C i of the clutch Cl is dependent on the input torque. The transmitted torque of the clutch Cl is

with M _c as the transmittable torque (clutch capacity) and Mi as the input torque. The clutch Cl acts in the closed state like a spring-damper element.

If it is a wet-start clutch, the third phase is started earlier, i. at greater slippage.

In phase 4, the moments of the internal combustion engine Mi _ce and the electric machine M _E 2 verrampt until the vehicle is predominantly driven by internal combustion engine.

Furthermore, the torque sources are controlled in such a way that jerks in the drive train are prevented or reduced.

The regulating device R shown in FIG. 1 comprises a state controller ZR and a state observer ZB and is connected to the internal combustion engine ICE, the electric machines E1, E2 and the clutch C1 for regulation purposes. The measured rotational speeds of the internal combustion engine ICE, the electric machines El, E2 and the driven wheels W are transmitted via corresponding lines to the control device R.

To control the drive train shown in Figure 1, the model shown in Figure 2 is used. The powertrain consists of two parts with the clutch Cl open. The left part of the model corresponds to the reduced one Inertia Ji _{Ce of} the internal combustion engine ICE coupled to the torsional damper D and the inertia J _e i of the electric machine El. The right side of the drive train is composed of the reduced inertia J _{g of} the transmission G, the propeller shaft and side shafts of the vehicle modeled as spring-damper element S, and the reduced inertia J _{c of} the fourth mass C formed from the vehicle mass and the tire , The gear ratios i _{g of} the gear G and i _{d of} the differential are assumed to be massless.

Furthermore, the following terms apply: J: moment of inertia, ω: angular velocity, c: spring constant, d: damping factor.

This results in the following state space representation using the usual equations of motion:

with the

States: x = (φ _ιce -φ _e ι, O) _11x , ω _el , φ _s -φ _c , ω _g , ω _c , M _L ) ^T ,

Measured quantities: y = (θ, ω _we , ω _e] , O, ω _g) ω _c f,

_Manipulated variables: u = (M _lce M _eλ M _e2 M _cl J and the perturbation: z = M _L = (F _Mlg + F _roll + F _flux ) • r _dyn , where i = i _g -i _d and the change the disturbance (Z) remains independent of the other states for the synchronization process.

A schematic representation of a control circuit according to the invention is shown in FIG 3. Here, the control device R is surrounded by a dashed line. At the output of the control device R, the manipulated variables u are preferably transmitted via the data bus system (CAN bus) of the vehicle to the control units of the transmission G or the clutch Cl, the internal combustion engine ICE and the electric machines El, E2. The measured variables y of the drive train are likewise preferably transmitted via the data bus system of the vehicle to the input of the control device R.

In a step Sl, the state vector x, by the

State observer ZB, preferably a Kalman filter, which filters out measurement noise and process noise, including the observation of vehicle resistances, estimated according to the following equation:

Here, Ai, Bi are considered as system matrices, Ki as Kalman feedback matrix and Ci as a linear relationship between the measured quantities y and the states Xi. Ki is usually using the solution of a Riccati equation and selectable parameters depending on the process and measurement noise.

Under the load moment M ₁ , the resistances of the vehicle are considered, which are mainly from air resistance, rolling friction and slope according to the equation

^M L = ^F Lufl + ^F S, e, _g + ^F Roll> ^WO b ^β i gi lt

A ^■ c

^F _Lu f, = - ^ - ^■ v ^{2 ■} p _Lu f, ' ^F s, _e , _g = rn - g - sm a and F _Roll = F _R ^■ v. As a result, the load torque can be very poorly considered or estimated for the controller design. It is possible to linearize it at an operating point, which is preferably regarded as an additional state and not as a system input.

Likewise, the drive train torsions are right and left of the clutch Cl, the φ from the differences φ _ιce _-φ Λ and _r -φ shown mitgeschatzt.

In step S2, the cost function J is solved offline with a Riccati equation or online with the aid of square programming, taking into account the driver's desired torque Msoii. The solution of the cost function J is the minimization of an energy function depending on the states x and manipulated variables u.

J = ±) f {x, u) ² ώ,

_{J =} i _|.? _{[(X (0} _χ _{t) γ _Q _{(* _(,)} _ _(/)) _{+ u (t} y _R _{M (O} μ..

(0

For a discrete-time controller, the cost function becomes a sum, taking into account the following factors:

wherein the individual factors of the cost function are weighted by the parameter vectors λ and γ. It can thus be limited or punished, for example, the response of the actuators or control errors. Likewise advantageous is a change in the weightings during driving, for example, depending on the driver's desired torque M _So ii possible.

With Ni and N ₂ as the prediction horizon in case the quadratic merit function (cost function) is determined online (in the microcontroller) or as Ni = 0 and N ₂ = ⁰⁰ if the merit function is calculated off-line. In both cases, the differential of the function is solved as a zero search.

In step S3, the sum of the state feedback and a reference vector forms the optimum manipulated variables u _opt : opt = -Lx + Vr

State feedback reference vector,

where: L: state feedback matrix L _r : reference matrix r: possible reference behavior, such as

Torque specification and slip presupposition, depending on the driver's request In this case, the reference vector has the task of interpreting possible driver requests and supplying the driver with the desired overall torque contour total torque command behavior to the controller.

Optionally, the optimum manipulated variables u _opt can be adjusted with precontrol values St of a superordinate controller.

FIG. 4 shows a simplified model of the drive train, which simplifies the numerical solution of the differential equation system. For the same reference numerals, reference is made to the preceding explanations. On the left side of the clutch Cl, the reduced inertia Ji _{ce of} the internal combustion engine ICE coupled to the torsional damper D and the inertia J _e i of the electric machine El in the inertia Ji have been summarized. The inertias J ₂ and J ₃ correspond to the inertias J _g and J _c, respectively.

For simplified modeling, the equations of motion according to Newton / Euler are used and combined into a linear state space form. x (t) = A (t) ^■ x (0 + B (O ^■ u (0 + H (0 ^■ z (0 y (0 = C (0-x (0 with A and B as system matrices for the state variables x and H as a disturbance matrix for the disturbance 1.

The state space model of the system when closed is thus:

In the state space model, the number of states does not decrease when the clutch Cl is in the closed position because the clutch Cl is treated in the closed position as a spring-damper element. In addition, it is possible to operate the system with permanent slip as a lock-up clutch in the torque converter.

Claims

claims

1. powertrain for a vehicle with an internal combustion engine (ICE), a first

Electric machine (El), a clutch (Cl), a second electric machine (E2), a transmission (G) and at least one driven wheel (W), wherein the internal combustion engine (ICE) with the first electric machine (El) is connected and through the Clutch (Cl) is connectable to the transmission input (GE),

/ -J -! o T if IT ¹ 1

O \ m -ϊ + - r ^

Transmission input (GE) is connectable, and the transmission output to the at least one driven wheel (W) is connected, characterized in that when switching the clutch (Cl) the moments of

Internal combustion engine (M _lce ), the first

Electric machine (M _E i), the clutch (M _C i) and the second

Electric machine (M _E2 ) by a state controller (ZR) are adjustable.

2. A method for controlling a drive train, with an internal combustion engine (ICE), a first

Electric machine (El), a clutch (Cl), a second electric machine (E2), a transmission (G) and at least one driven wheel (W), the internal combustion engine (ICE) with the first

Electric machine (El) is connected and through the

Coupling (Cl) with the transmission input (GE) is connectable, the second electric machine (E2) with the

Internal combustion engine (Mj. _Ce ), the first

Electric machine (M _E i), the clutch (M _C i) and the second

Electric machine (M _E 2) are controlled by a state controller (ZR).

3. The method according to claim 2, characterized in that non-measured state variables are estimated by a Statebecbachter (ZB).

4. The method according to claim 3, characterized in that a load torque (M _L ) and Antriebsstrangtorsionen by the state observer (ZB) are estimated.

5. The method according to any one of claims 2 to 4, characterized in that the regulation of the drive train is carried out by means of a cost function.

6. The method according to claim 5, characterized in that the weighting of the factors of the cost function is changed in dependence on the driver's request.

7. The method according to any one of claims 2 to 6, characterized in that the switching of the clutch (Cl) in a change from a first operating mode in which the vehicle is driven purely electrically, in a second operating mode in which the vehicle is purely internal combustion engine is driven takes place.