Method for controlling at least one first drive unit of a vehicle as a function of operating states of a second drive unit of the vehicle during a switchover operation, and control device

Abstract

A method for controlling at least one first drive unit of a vehicle as a function of operating states of a second drive unit of the vehicle during a switchover operation. The first drive unit is associated with a first control unit and the second drive unit s associated with a second control unit. At least one message is transmitted to the first control unit by the second control unit. The message includes: a first desired value TQ1 of a controlled variable prior to the switchover operation; a second desired value TQ2 of the controlled variable after the switchover operation; and information on the angular position of a shaft of the second drive unit at the projected point of time of the switchover operation.

Claims

1. A method of controlling a first drive unit of a vehicle in dependence upon an operating state of a second drive unit of the vehicle during a switchover operation from the second drive unit to the first drive unit, the method comprising: providing a first control unit operatively associated with the first drive unit and a second control unit operatively associated with the second drive unit, the first control unit controlling the first drive unit and the second control unit controlling the second drive unit by way of a control variable TQ having given desired values TQ1 and TQ2; in preparation for the switchover operation, transmitting at least one data packet from the second control unit to the first control unit, the data packet including: a first desired value TQ1 of a control variable prior to the switchover operation; a second desired value TQ2 of the control variable after the switchover operation; and data indicating an angular position of a shaft of the second drive unit at a point in time of the planned switchover operation; effecting a change in the control variable from the value TQ1 prior to the switchover to the value TQ2 after the switchover by providing with the first control unit new desired values for the first drive unit prior to the switchover; and defining a time instant for the switchover based on the value TQ2 and effecting the switchover between the first and second drive units at the defined time instant for the switchover by ceasing to drive the vehicle with the first drive unit and driving the vehicle with the second drive unit or ceasing to drive the vehicle with the second drive unit and driving the vehicle with the first drive unit.

2. The method according to claim 1, wherein the data regarding the angular position is an angle .sub.switch of the shaft of the second drive unit at the point in time of the planned switchover operation.

3. The method according to claim 2, which further comprises ascertaining an angle .sub.switch of a shaft of the first drive unit at the point in time of the planned switchover operation by the first control unit, wherein the angle .sub.switch is ascertained from:
.sub.switch=(.sub.switch.sub.0)/K, where .sub.0 represents an angular offset between the shafts of the first and second drive units with respect to one another and K represents a ratio between a rotational speed of the first drive unit and a rotational speed of the second drive unit.

4. The method according to claim 3, which comprises, for determining the angular offset .sub.0, transmitting a current angle .sub.message to the first control unit and storing a current angle a .sub.message, and ascertaining the angular offset .sub.0 from:
.sub.0=.sub.message.sub.message*K.

5. The method according to claim 4, which comprises adapting the angular offset .sub.0 by repeating the ascertaining step.

6. The method according to claim 3, which comprises ascertaining the ratio K by transmitting to the first control unit one after the other two actual values .sub.message1 and .sub.message2 of the angle of the shaft of the second drive unit and storing associated actual values .sub.message1 and .sub.message2 of the angle of the shaft of the first drive unit, and determining the ratio K of the rotational speeds from:
K=(.sub.message2.sub.message1)/(.sub.message2.sub.message1).

7. The method according to claim 6, which comprises adapting the ratio K of the rotational speeds by repeating the ascertaining step.

8. The method according to claim 3, which comprises ascertaining the ratio K by transmitting data regarding the rotational speed d/dt of the second drive unit to the first control unit and storing associated data regarding the rotational speed d/dt of the first drive unit, and determining the ratio K of the rotational speeds from:
K=(d/dt)/(d/dt).

9. The method according to claim 8, which comprises adapting the ratio K of the rotational speeds by repeating the ascertaining step.

10. The method according to claim 1, wherein the data regarding the angular position of the shaft of the second drive unit is an angular offset .sub.switch of the shaft of the second drive unit at a point in time of the planned switchover operation, and wherein:
.sub.switch=.sub.switch.sub.message.

11. The method according to claim 10, which further comprises ascertaining an angle .sub.switch of a shaft of the first drive unit at the point in time of the planned switchover by the first control unit, wherein the angle .sub.switch is ascertained from:
.sub.switch=.sub.message.sub.switch/K, wherein a .sub.message represents the angle of the shaft of the first drive unit that is stored when the data packet is received by way of the first control unit and K represents a ratio between a rotational speed ratio of the first drive unit and a rotational speed of the second drive unit.

12. The method according to claim 10, which comprises ascertaining the ratio K by transmitting to the first control unit one after the other two actual values .sub.message1 and .sub.message2 of the angle of the shaft of the second drive unit and storing associated actual values .sub.message1 and .sub.message2 of the angle of the first drive unit, and determining the ratio K of the rotational speeds from:
K=(.sub.message2.sub.message1)/(.sub.message2.sub.message1).

13. The method according to claim 11, which comprises adapting the ratio K of the rotational speeds by repeating the ascertaining step.

14. The method according to claim 10, which comprises ascertaining the ratio K by transmitting data regarding the rotational speed d/dt of the second drive unit to the first control unit and storing associated data regarding the rotational speed d/dt of the first drive unit, and determining the ratio K of the rotational speeds from:
K=(d/dt)/(d/dt).

15. The method according to claim 14, which comprises adapting the ratio K of the rotational speeds by repeating the ascertaining step.

16. The method according to claim 1, which comprises preparing a change in the control variable from the desired value TQ1 prior to the switchover operation to the desired value TQ2 after the switchover operation by providing with the first control unit new desired values of the first drive unit prior to the point in time of the switchover.

17. A computer program product, comprising a computer-readable medium and non-transitory program code stored on the computer-readable medium and configured, upon being executed on a computing unit, to instruct the computing unit to perform a method of controlling a first drive unit of a vehicle in dependence upon an operating state of a second drive unit of the vehicle during a switchover operation from the second drive unit to the first drive unit, the method comprising: using a first control unit operatively associated with the first drive unit and a second control unit operatively associated with the second drive unit, the first control unit controlling the first drive unit and the second control unit controlling the second drive unit by way of a control variable TQ having given desired values TQ1 and TQ2; in preparation for the switchover operation, transmitting at least one data packet from the second control unit to the first control unit, the data packet including: a first desired value TQ1 of a control variable prior to the switchover operation; a second desired value TQ2 of the control variable after the switchover operation; and data indicating an angular position of a shaft of the second drive unit at a point in time of the planned switchover operation; effecting a change in the control variable from the value TQ1 prior to the switchover to the value TQ2 after the switchover by providing with the first control unit new desired values for the first drive unit prior to the switchover; and defining a time instant for the switchover based on the value TQ2 and effecting the switchover between the first and second drive units at the defined time instant for the switchover by ceasing to drive the vehicle with the first drive unit and driving the vehicle with the second drive unit or ceasing to drive the vehicle with the second drive unit and driving the vehicle with the first drive unit.

18. A control device for drive units of a vehicle, the control device comprising: a first control unit allocated to a first drive unit of the vehicle; a second control unit allocated to a second drive unit of the vehicle; said first and second control units being configured to control the first and second drive units, respectively, by way of a control variable TQ having given desired values TQ1 and TQ2; a communication link between said first control unit and said second control unit, wherein the control device is configured, during a switching operation at which an operation of the vehicle is switched from being driven by the first drive unit to being driven by the second drive unit or vice versa, to cause a data packet to be transmitted from the second control unit to the first control unit, the data packet including: a first desired value TQ1 of a control variable prior to the switchover; a second desired value TQ2 of the control variable after the switchover; and data regarding an angular position of a shaft of the second drive unit at a point in time of the planned switchover; and wherein the control device is configured to define the point in time of the planned switchover based on the angular position of the shaft of the second drive unit.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Exemplary embodiments are further explained with reference to the drawing. The single FIGURE illustrates schematically a control unit in accordance with one embodiment of the invention for coordinating two drive units.

DESCRIPTION OF THE INVENTION

(2) The figure illustrates schematically the drive train 2 of a vehicle, not further illustrated, and said drive train is embodied as a parallel hybrid system. A first drive unit 3 is provided that is embodied in the illustrated embodiment as an electric motor, and a second drive unit 4 that is embodied in the illustrated embodiment as a combustion engine. Both the combustion engine and also the electric motor provide torque and comprise a connection that transmits torque to the drive train 2.

(3) The first drive unit 3 is allocated a first control unit 5 that in this embodiment is an inverter. The second drive unit 4 is allocated a second control unit 6. The control units 5, 6 are in each case connected to the drive units 3, 4 by way of signal lines 7, 8 and are part of a control device 1 for the drive units 3, 4.

(4) A communication connection 9 by way of example a CAN-bus or a FlexRay-Bus is provided between the first control unit 5 and the second control unit 6.

(5) The control device 1 is embodied in such a manner that during a switchover operation a data packet is transmitted from the second control unit 4 by way of the communication connection 9 to the first control unit 3, wherein the data packet comprises the first desired value TQ1 of the control variable prior to the switchover, the second desired value TQ2 of the control variable after the switchover and also data regarding an angle position of a shaft of the second drive unit 4 at the point in time of the planned switchover.

(6) The control device 1 renders it possible to perform a compensation of the torque of the combustion engine by means of the electric motor if it is necessary to perform a compensation procedure during a switchover.

LIST OF REFERENCE NUMERALS

(7) 1 Control device 2 Drive train 3 First drive unit 4 Second drive unit 5 First control unit 6 Second control unit 7 Signal line 8 Signal line 9 Communication connection