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

Abstract

A circuit for controlling a hybrid drivetrain, including an alternating current electric machine, a first battery, a second battery, a first pair of complementary transistor switches arranged to complete a first direct current circuit to charge the first battery or to complete a second direct current circuit to discharge the first battery, a second pair of complementary transistor switches arranged in parallel and arranged to complete a third direct current circuit to charge the second battery or to complete a fourth direct current circuit to discharge the second battery, an inverter arranged to convert direct current electrical energy from the first and second batteries into alternating current electrical energy, arranged to supply the alternating current electrical energy to the electric machine, and also arranged to transmit voltage modulations caused by damping vibrations within the drivetrain, and a control unit operatively arranged to control the first and second pair of switches.

Claims

1. A circuit for controlling a hybrid drivetrain and a pair of batteries in the hybrid drivetrain of a motor vehicle, comprising: an alternating current electric machine arranged to drive said hybrid drivetrain at least some of the time; a first battery arranged to provide direct current electrical power; a second battery arranged to provide direct current electrical power; a first pair of complementary transistor switches arranged in parallel and arranged to complete a first direct current circuit to charge said first battery or to complete a second direct current circuit to discharge said first battery; a second pair of complementary transistor switches arranged in parallel and arranged to complete a third direct current circuit to charge said second battery or to complete a fourth direct current circuit to discharge said second battery; an inverter arranged to convert direct current electrical energy from said first and second batteries into alternating current electrical energy, arranged to supply said alternating current electrical energy to said electric machine, and also arranged to transmit modulations responsive to residual vibrations from a torsional vibration damper within said drivetrain to one of said first, second, third, or fourth direct current circuits via one of said switches; and, a control unit operatively arranged to control said first and second pair of switches.

2. The circuit recited in claim 1, wherein said modulations responsive to said residual vibrations lie in a range of 60 to 100 Hz.

3. The circuit recited in claim 1, wherein said control unit is operatively arranged to control said first and second pair of switches such that said first battery is charging when said second batter is discharging.

4. The circuit recited in claim 1, wherein said control unit is operatively arranged to control said first and second pair of switches such that said second battery is charging when said first battery is discharging.

5. The circuit recited in claim 1, wherein said control unit is operatively arranged to control said first and second pair of switches such that said first battery is charging and said second battery is charging during recovery of the drivetrain while the motor vehicle is decelerating.

6. The circuit recited in claim 1, wherein said control unit is operatively arranged to control said first and second pair of switches such that said first battery is discharging and said second battery is discharging while starting a combustion engine of the motor vehicle, or when the drivetrain is in a boost mode.

7. The circuit recited in claim 1, wherein each of said transistor switches comprises an insulated-gate bipolar transistor.

8. A method for controlling a hybrid drivetrain of a motor vehicle, said motor vehicle driven at least some of the time by an electric machine, comprising: powering said electric machine to drive said hybrid drivetrain at least some of the time with a first battery; powering said electric machine to drive said hybrid drivetrain at least some of the time with a second battery; charging and discharging said first and second batteries via a direct current circuit; inverting direct current electrical energy provided by at least one of said batteries into alternating current electrical energy to power said electric machine; transmitting modulations responsive to residual vibrations from a torsional vibration damper within said drivetrain into said direct current charging circuit; controlling, with a control unit, a first pair of complementary transistor switches arranged in parallel and arranged to complete a circuit to charge said first battery or to complete a circuit to discharge said first battery; and, controlling, with the control unit, a second pair of complementary transistor switches arranged in parallel and arranged to complete a circuit to charge said second battery or to complete a circuit to discharge said second battery.

9. The method recited in claim 8, wherein said modulations responsive to said residual vibrations lie in a range of 60 to 100 Hz.

10. The method recited in claim 8, wherein, in a first stage, said controlling steps function to charge said first battery when said second battery is discharging.

11. The method recited in claim 8, wherein, in a second stage, said controlling steps function to charge said second battery when said first battery is discharging.

12. The method recited in claim 8, wherein, in a third stage, said controlling steps function to charge said first and second batteries at the same time.

13. The method recited in claim 8, wherein, in a fourth stage, said controlling steps function to discharge said first and second batteries at the same time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which:

(2) FIG. 1 is a circuit diagram for controlling the charge states of batteries of a battery device;

(3) FIG. 2 is a depiction of charging processes of a conventional battery device having a battery and the battery device of the present invention, over time;

(4) FIG. 3A is a depiction of the currents appearing in a hybrid drivetrain during a compensation of residual vibrations of a torsional vibration damper at a conventional battery device over time;

(5) FIG. 3B is a depiction of a single electrical machine alternately charging a first battery and discharging a second battery over time;

(6) FIG. 3C is a depiction of a single electrical machine alternately discharging a first battery and charging a second battery over time; and,

(7) FIG. 4 is a circuit diagram similar to the circuit diagram of FIG. 1 for controlling the charge state of batteries of a battery device.

DETAILED DESCRIPTION OF THE INVENTION

(8) At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred aspects, it is to be understood that the invention as claimed is not limited to the disclosed aspects.

(9) Furthermore, it is understood that this invention is not limited to the particular methodology, materials and modifications described and, as such, may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present invention, which is limited only by the appended claims.

(10) Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods, devices, and materials are now described.

(11) FIG. 1 shows circuit diagram 2 of battery device 1, having first and second batteries 3, 4 with the same or different capacity, control unit 5 and inverter 6, which are connected to each other by means of grounding line 7. Inverter 6 forms the interface to the electric machine (not shown), and transforms the direct current of batteries 3, 4 into a plurality of alternating current phases, of which only one phase w is depicted here symbolically, to drive the electric machine.

(12) Situated between inverter 6 and batteries 3, 4 in each case are two parallel-switched switches 8, 9, 10, 11 in the form of IGBTs, connected oppositely in regard to their switch position, so that with gates of switches 8, 9, 10, 11 connected in each case with the same signal level through logic switches 12, 13, in each case one switch of battery 3, 4 is switched to conductive and the other to non-conductive. In this case, the gates are connected so that, for example, at battery 3, when a positive level is present at output Out1 of control unit 5, switch 8 of battery 3 and switch 11 of battery 4 are switched so that when an AC signal is present at access line 14 only battery 3 receives charging current through closed switch 8, while switch 10 which is responsible for the charging current of battery 4 remains open. In regard to discharge current, switch 9 of battery 3 is open, and a discharge current is able to flow from battery 4 through closed switch 11.

(13) If the level at output Out1 is set to low, inversely switched logic switches 12, 13 issue a level to the gates of switches 9, 10, so that the discharge current from battery 3 and the charge current for battery 4 are switched through switches 9 and 10, respectively, while switches 8, 11 remain open.

(14) The connection of output Out1 of control unit 5 is dependent on the charge states ascertained in batteries 3, 4 by devices 15, 16, which are made up of the charge states of the individual cells and are fed to inputs In1, In2 of control unit 5 by means of signal lines 17, 18.

(15) FIG. 2 shows diagram 19, in which curves 20, 21, 22 represent the charge states of batteries against time in the range of, for example, several minutes to several hours, where these charge states may vary and depend among other things on the capacity of the batteries and their electrode kinetics. The actual excitations of the drivetrain, which the torsional vibration damper in the drivetrain does not damp adequately, cause small waves in the range of approximately 100 Hz in the DC section which is downline from the inverter. The depiction of the long-term charging process and the depiction of the AC portion of the excitations are shown overdrawn in Diagram 19 to explain the effects.

(16) Curve 22, identified using the symbols +, shows a conventional battery device having a charge state of approximately 30% during a compensation of residual vibrations of a torsional vibration damper by means of an electric machine, which is connected to the single battery of the battery device. The battery is charged and discharged here using micro-cycles, which may lie within the range of the frequency of the occurring residual vibrations of the torsional vibration damper. The battery may be damaged by such micro-cycles and have a short service life.

(17) Curves 20, 21, identified using the symbols x and o, respectively, show the charge states of battery device 1 of FIG. 1, first and second batteries 3, 4 having different capacitiesas is evident from FIG. 2. The connection of batteries 3, 4 in accordance with circuit diagram 2 results in the uniform charging and discharging of the batteries over macro-cycles, which can be made to approximate the charging and discharging processes recommended by the manufacturer. In this case, the battery with curve 20 has the smaller capacity, so that it determines the macro-cycles, which may range from a few minutes to a few hours in length. The charge states are measured at the batteries and are registered by control unit 5, which controls the switching of switches 8, 9, 10, 11 to adjust the macro-cycles. In one embodiment, the battery with curve 20 is charged up to a charge state of 80% of the total capacity and discharged to 20% thereof, which results in a recharging of between 20% and 32% of its total capacity for the battery having the greater capacity.

(18) FIG. 3A shows diagram 23, with currents occurring cyclically at battery devices during the compensation of residual vibrations of a torsional vibration damper by means of an electric machine connected to the batteries of the battery devices, over time. FIG. 3B is a depiction of a single electrical machine alternately charging a first battery and discharging a second battery over time. In FIG. 3A, curve 24 shows the currents of a conventional battery device having a single battery, which is recharged micro-cyclically at the frequency of the alternating currents. In FIG. 3B and FIG. 3C, batteries connected in accordance with circuit diagram 2 of FIG. 1, on the other hand, are only charged or discharged, so that over a relatively long macro-cycle they undergo only positive or negative current cycles, as may be seen from curves 25, 26 which each show the current of one battery. Curve 25 shows current for one of batteries 3 or 4 during a first plurality of time periods T1 in which residual torque from the crankshaft and torsional vibration damper is greater than a mean for the residual torque. During time periods T1, electric machine 27 is controlled by control unit 5 to operate as a generator by charging the one of batteries 3 or 4. Curve 26 shows current for the other of batteries 3 or 4 during a second plurality of time periods T2 in which residual torque from the crankshaft and torsional vibration damper is greater than a mean for the residual torque. During time periods T2, electric machine 27 is controlled by control unit 5 to operate as a motor by discharging the other of batteries 3 or 4.

(19) FIG. 4 shows circuit diagram 2a of first and second batteries 3a, 4a with the same or different capacity, control unit 5a and inverter 6a, which are connected to each other by means of grounding line 7a and access line 14a. Inverter 6a forms the interface to electric machine 27, and converts the DC current of batteries 3a, 4a to a plurality of AC phases u, v, w to drive electric machine 27. At the same time, phase-selective commutation currents or commutation voltages in the range from 100 Hz to 1 kHz are output, while the voltage modulations received from the residual vibrations 98 of the torsional vibration damper 99 via electric machine 27 are transmitted via inverter 6a to the DC network, i.e., via access line 14a and grounding line 7a to the batteries, lie within the range from approximately 60 to 100 Hz. Switches 8a, 9a, 10a, 11a are addressed directly by control unit 5a by means of control lines 28, 29, 30, 31, and are thereby placed in a through-connected or open state.

(20) Because of the free design of the connection of switches 8a, 9a, 10a, 11a by control unit 5a, one of batteries 3a, 4a can be charged while the other is being discharged. To this end, for example, switch 8a is connected through in the direction of battery 3a and switch 11a is connected through in the direction of inverter 6a, while switches 9a, 10a are open. This causes battery 3a to be charged and battery 4a to be discharged. By closing switches 8a, 10a in the same direction, both batteries 3a, 4a are charged, for example, during recovery of the drivetrain while the motor vehicle is decelerating, and by closing switches 9a, 11a in the same direction both batteries 3a, 4a are discharged simultaneously, for example, while starting the combustion engine or when the drivetrain is in boost mode.

(21) Control unit 5a has a signal connection to batteries 3a, 4a and inverter 6a by means of signal lines 17a, 18a, 32, and thereby controls the charging of the batteries and the commutation of electric machine 27.

(22) Thus, it is seen that the objects of the present invention are efficiently obtained, although modifications and changes to the invention should be readily apparent to those having ordinary skill in the art, which modifications are intended to be within the spirit and scope of the invention as claimed. It also is understood that the foregoing description is illustrative of the present invention and should not be considered as limiting. Therefore, other embodiments of the present invention are possible without departing from the spirit and scope of the present invention.

LIST OF REFERENCE NUMBERS

(23) 1 battery device 2 circuit diagram 2a circuit diagram 3 battery 3a battery 4 battery 4a battery 5 control unit 5a control unit 6 inverter 6a inverter 7 grounding line 7a grounding line 8 switch 8a switch 9 switch 9a switch 10 switch 10a switch 11 switch 11a switch 12 logic switch 13 logic switch 14 access line 14a access line 15 device 16 device 17 signal line 17a signal line 18 signal line 18a signal line 19 diagram 20 curve 21 curve 22 curve 23 diagram 24 curve 25 curve 26 curve 27 electric machine 28 control line 29 control line 30 control line 31 control line 32 signal line In1 input In2 input Out1 output u phase v phase w phase