Hybrid Motor Vehicle and Method for Controlling Operation of a Hybrid Motor Vehicle

• US 20090146615A1
• Filed: 10/19/2005
• Published: 06/11/2009
• Est. Priority Date: 11/16/2004
• Status: Active Grant

• Current Assignee: Skoda Auto A.S. (Volkswagen AG), Volkswagen AG
• Original Assignee: Skoda Auto A.S. (Volkswagen AG), Volkswagen AG
• Inventors: Holz, Matthias, Pott, Ekkehard, Zillmer, Michael, Prochazka, David
• Granted Patent: US 8,020,651 B2
• Time in Patent Office: Days
• US Class Current: 322/23
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60L 1/00 Supplying electric power to auxiliary equipment of vehicles circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 58/13 Maintaining the SoC within a determined range
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors

Abstract

The invention relates to a method for controlling an operation of a motor vehicle equipped with a hybrid drive unit (10), which comprises a combustion engine (12) and at least one electric machine (14) that can be selectively operated as a motor or as a generator. The electric machine (14), when in generator mode, charges an energy store (22) and/or supplies power to a vehicle electrical system (24) of the motor vehicle. The invention provides that in generator mode the electric machine (14) is operated in alternating intervals, while maintaining predefined boundary conditions, wherein: (a) in a first interval, the electric machine (14) is operated with a first high electrical power output that is higher than an actual power consumption of the vehicle electrical system (24) of the motor vehicle; and (b) is switched off in a second interval. This largely prevents the electric machine (14) from approaching operating points under light load which have a low efficiency and achieves a fuel advantage in comparison to a continuous operating mode.

Claims

1. Method for controlling an operation of a motor vehicle with a hybrid drive unit (10), which comprises an internal combustion engine (12) and at least one electric machine (14) which can be selectively operated as a motor or a generator, wherein the electric machine (14) charges in generator operation an energy store (24) and/or powers a vehicle electrical system (26) of the motor vehicle, characterized in that depending on maintaining predetermined boundary conditions, the electric machine (14) operates in generator mode in alternating intervals, wherein

(a) in a first interval, the electric machine (14) is operated with a first, high electric power output which is greater than an actual power consumption of the vehicle electrical system (26), and

(b) is switched off in a second interval.

2. Method according to claim 1, characterized in that in the second interval the vehicle electrical system (26) is supplied from the energy store (24) and/or from a car battery (30).

3. Method according to claim 1, characterized in that the first interval is terminated when a charge state (LZ) of the energy store (24) reaches an upper switching threshold (LZ_2), and the second interval is terminated when the charge state (LZ) of the energy store (24) reaches a lower switching threshold (LZ_1).

4. Method according to claim 3, characterized in that the upper switching threshold (LZ_2) and/or the lower switching threshold (LZ_1) are, independent of each other, at most about 20%, in particular at most about 10%, most preferably at most about 5% above or below, respectively, a desired charge state (LZ_S) with reference to a maximum charge state of the energy store (24).

5. Method according to claim 1, characterized in that the alternating operation of the electric machine (14) is used when the actual power demand from the vehicle electrical system (26) and/or the energy store (24) fall below a threshold value, in particular when the power demand is smaller than 1200 W, preferably smaller than 800 W, most preferably smaller than 500 W.

6. Method according to claim 1, characterized in that the alternating operation of the electric machine (14) is used when a ratio of the actual power demand of vehicle electrical system (26) and/or energy store (24) to an actual maximum generator power supply from the electric machine (14) falls below a threshold value, in particular is smaller than 0.15, preferably smaller than 0.10, most preferably smaller than 0.05.

7. Method according to claim 1, characterized in that the alternating operation of the electric machine (14) is used when an efficiency advantage of the alternating operation compared to a continuous operation exceeds a threshold value, in particular at least 2%, preferably at least 5%, most preferably at least 10%.

8. Method according to claim 1, characterized in that the alternating operation of the electric machine (14) is used in a rotation speed range where the efficiency of the electric machine (14) is slightly dependent on the rotation speed, in particular at rotation speeds (n) of ≧

1250 min<sup>−

1</sup>, preferably ≧

1500 min<sup>−

1</sup>, most preferably ≧

2000 min<sup>−

1</sup>.

9. Method according to claim 1, characterized in that the alternating operation of the electric machine (14) is used when a desired charge state (LZ_S) of the energy store (24) maintains a minimum separation from a lower and/or an upper permissible charge limit value, in particular a separation of 20%, preferably of 10%, most preferably of 5%.

10. Method according to claim 1, characterized in that the alternating operation of the electric machine (14) is used when at least one of the following boundary conditions is satisfied:

a minimum separation between an actual torque of the internal combustion engine (12) and a maximum torque of the internal combustion engine is maintained;

the internal combustion engine (12) is not actually operated with an enriched mixture to protect components;

the vehicle travels at an actual minimum speed; and

a minimum gear of a vehicle gear transmission (16) is engaged.

11. Motor vehicle with a hybrid drive unit (10), which comprises an internal combustion engine (12) and at least one electric machine (14) which can be selectively operated as a motor or a generator, wherein in generator operation the electric machine (14) charges an energy store (24) and/or powers a vehicle electrical system (26) of the motor vehicle, characterized by control means configured to operate the electric machine (14) depending on maintaining predetermined boundary conditions in generator mode in alternating intervals, wherein

(a) in a first interval, the electric machine (14) is operated with a first, high electric power output which is greater than an actual power consumption of the vehicle electrical system (26), and

(b) is switched off in a second interval.