Method for Controlling an Output Torque of an Electric Variable Transmission by Battery Power Management

• US 20100252344A1
• Filed: 04/02/2009
• Published: 10/07/2010
• Est. Priority Date: 04/02/2009
• Status: Active Grant

• Current Assignee: Daimler AG (Mercedes-Benz Group AG)
• Original Assignee: Daimler AG (Mercedes-Benz Group AG)
• Inventors: GIERAY, Claus, LOSCHKO, Birgit
• Granted Patent: US 7,971,669 B2
• Time in Patent Office: Days
• US Class Current: 180/65.290
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• 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 2710/086 Power
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: F16H 2037/0873 with switching, e.g. to change ranges
• CPC Class Codes: F16H 2037/102 the input or output shaft of the transmission is connected or connectable to two or more differentials
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

In a method for controlling an output torque of an electric variable transmission having an input coupled to a combustion engine and at least one electric motor that is at least feedable by a battery and able to recuperate energy into the battery, the battery power is limited to a maximum continuous battery power when the transmission is in a stationary operating point with a continuous revolution speed. The battery power is increased and limited to a maximum transient battery power that is greater than the maximum continuous battery power in a non-stationary operating point, upon a request for changing the gear-ratio (ratio between transmission input and output-speed) or upon a request for changing the transmissions output revolution speed.

Claims

1. A method for controlling an output torque of an electric variable transmission having an input that is coupled to a combustion engine, and at least one electric motor that is feedable by a battery, and is able to recuperate energy into the battery, said method comprising:

limiting battery power to a maximum continuous battery power when the transmission is in a stationary operating point with a continuous revolution speed;

raising the battery power and limiting it to a maximum transient battery power which is greater than the maximum continuous battery power in a non-stationary operating point, upon a request for changing the gear-ratio between transmission input and output-speed, or upon a request for changing the transmissions output revolution speed.

2. The method according to claim 1, wherein battery discharging power is restricted to a maximum transient battery discharging power when boosting.

3. The method according to claim 1, wherein battery charging power is restricted to a maximum transient charging power when recuperating.

4. The method according to claim 2, wherein an absolute value of the maximum transient battery charging power equals an absolute value of the maximum transient battery discharging power.

5. The method according to claim 3, wherein an absolute value of the maximum transient battery charging power equals an absolute value of the maximum transient battery discharging power.

6. The method according to claim 2, wherein an absolute value of the maximum transient battery charging power differs from an absolute value of the maximum transient battery discharging power.

7. The method according to claim 3, wherein an absolute value of the maximum transient battery charging power differs from an absolute value of the maximum transient battery discharging power.

8. The method according to claim 1, wherein the battery power is calculated as the sum of mechanical powers of the electric motors and an overall loss of power due to friction, heat, ohmic drop and battery losses.

9. The method according to claim 8, wherein battery power required in the stationary operating point is calculated by summing transmission output power, and an overall loss of power, and subtracting power of the combustion engine.

10. The method according to claim 8, wherein battery power required in the non-stationary operating point is calculated by summing transmission output power, an overall loss of power and an inertia power required for compensating inertia operative in the transmission, and subtracting a power of the combustion engine.

11. The method according to claim 8, wherein battery power required in the non-stationary operating point is calculated by summing transmission output power, an overall loss of power and a function of an inertia power required for compensating inertia operative in the transmission, and subtracting a power of the combustion engine.

12. The method according to claim 1, wherein said electric variable transmission is coupled to two electric motors.

13. The method according to claim 1, wherein said electric variable transmission is in a hybrid vehicle.