Method for controlling a hybrid drivetrain and battery device in the hybrid drivetrain

Abstract

A method for controlling a hybrid drivetrain in a motor vehicle having an internal combustion engine, which has a crankshaft and an electric machine which can be operated as a motor and generator, having a rotor operatively connected to the crankshaft, having a torsional vibration damper operatively connected to the crankshaft, having a battery device for exchanging electrical energy with the electric machine, and having a control unit for controlling the battery device and the electric machine, and a corresponding battery device. To operate the electric machine with rapidly changing motor and generator operation without damaging the battery device, the electric machine is operatively connected to at least first and second electric batteries of the battery device, where at least part of the time one of the batteries is charged in the rhythm of occurring residual vibrations of the torsional vibration damper, while the other is discharged.

What is claimed is: 
     
         1 . A method for controlling a hybrid drivetrain in a motor vehicle having an internal combustion engine, which has a crankshaft and an electric machine which can be operated as a motor and generator, having a rotor operatively connected to the crankshaft, having a torsional vibration damper operatively connected to the crankshaft, having a battery device for exchanging electrical energy with the electric machine, and having a control unit for controlling the battery device and the electric machine, the method comprising the following steps:
 operatively connecting the electric machine to at least first and second electric batteries of the battery device; and,   charging the first hatter, using the electric machine, in the rhythm of occurring residual vibrations of the torsional vibration damper, while the second battery is being discharged.   
     
     
         2 . The method as recited in  claim 1 , wherein the batteries are switched by the control unit to a charging or discharging state, depending on their charge condition. 
     
     
         3 . The method as recited in  claim 2 , wherein the battery switched to the charging state is charged by means of half-waves that lie above a mean torque of the residual vibrations, which are converted to electrical energy by driving the electric machine, and the battery switched to the discharging state drives the electric machine in phases of half-waves that lie below a. mean torque of the residual vibrations to compensate. 
     
     
         4 . A battery device for carrying out the method as recited in  claim 1 , comprising:
 first and second batteries which can be connected by means of a plurality of current-direction-sensitive switches and a control unit for controlling the switches, as well as a converter.   
     
     
         5 . The battery device as recited in  claim 4 , wherein in each of the batteries a device determines the charge condition, which has a signal connection to the control unit. 
     
     
         6 . The battery device as recited in  claim 4 , wherein each battery has a switch for charging and discharging, and the switches can be operated alternately by the control unit, 
     
     
         7 . The battery device as recited in  claim 4 , wherein the switches are bipolar transistors having insulated gate electrodes, switched by the control unit. 
     
     
         8 . The battery device as recited in  claim 7 , wherein an inverting logic switch is situated between each switch and an output of the control unit, and the other two switches are connected directly to an output. 
     
     
         9 . The battery device as recited in  claim 1 , wherein the switches can be addressed individually by the control unit to control them. 
     
     
         10 . The battery device as recited in  claim 4 , wherein the batteries are lithium-ion batteries. 
     
     
         11 . The battery device as recited in  claim 4 , wherein the batteries have different capacities.