Method for executing regenerative braking in a mild hybrid system

Patent metadata

Field	Value
Publication number	US-10780784-B2
Application number	US-201816178136-A
Country	US
Kind code	B2
Filing date	Nov 1, 2018
Priority date	Nov 29, 2017
Publication date	Sep 22, 2020
Grant date	Sep 22, 2020

Abstract

A method for executing regenerative braking of a mild hybrid system may include performing, when a brake is operated while a vehicle having the mild hybrid system is traveling, regenerative braking only in a state in which a wheel torque is greater than a clutch load torque by a threshold, thereby preventing occurrence of an abnormal engine-off state during regenerative braking.

First claim

What is claimed is:

1. A method for executing regenerative braking of a mild hybrid system, the method comprising:
calculating a clutch load torque when a brake is operated while a vehicle having the mild hybrid system is traveling;
comparing the clutch load torque with a wheel torque; and
performing regenerative braking only in a state in which the wheel torque is greater than the clutch load torque by a threshold, thereby preventing occurrence of an abnormal engine-off state during regenerative braking.

2. The method of claim 1 , wherein the clutch load torque is calculated as a sum of a load torque of a mild hybrid starter and generator (MHSG) and a torque of engine friction.

3. The method of claim 1 , further comprising:
before the wheel torque and the clutch load torque are compared, determining a vehicle driving condition, determining whether a power electronics (PE) part is normal, and determining whether engine friction is stabilized.

4. The method of claim 3 , further comprising:
deactivating the regenerative braking when a result of any one of determining the vehicle driving condition, determining whether the PE part is normal, and determining whether the engine friction is stabilized is negative.

5. The method of claim 3 , wherein:
determining the vehicle driving condition includes determining whether a vehicle speed and a revolutions per minute (RPM) are more than corresponding predetermined values, determining whether a state-of-charge (SOC) of a high-voltage battery is less than a predetermined value, and determining whether a clutch is in a closed state, and
deactivating the regenerative braking when a result of any one of determining whether the vehicle speed and the RPM are more than corresponding predetermined values, determining whether the SOC of the high-voltage battery is less that the predetermined value, and determining whether the clutch is in the closed state is negative.

6. The method of claim 3 , wherein:
determining whether the PE part is normal includes determining whether a mild hybrid starter and generator (MHSG) operates normally, determining whether a belt of the MHSG is deteriorated, and determining whether a high-voltage battery operates normally, and
deactivating the regenerative braking when a result of any one of determining whether the MHSG operates normally, determining whether the belt of the MHSG is deteriorated, and determining whether the high-voltage battery operates normally is negative.

7. The method of claim 3 , wherein:
determining whether the engine friction is stabilized includes determining whether a water temperature value, a cumulative mileage, and a starting time are more than corresponding reference values, and
deactivating the regenerative braking when a result of any one of determining whether a water temperature value, a cumulative mileage, and a starting time are more than corresponding reference values is negative.

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Choi Kwang-Seok

Classifications

• B60W2510/0275

  Clutch torque · CPC title

• F16D61/00

  Brakes with means for making the energy absorbed available for use (F16D57/00 takes precedence) · CPC title

• B60Y2200/92

  Hybrid vehicles · CPC title

• B60T1/10

  by utilising wheel movement for accumulating energy, e.g. driving air compressors · CPC title

• B60W30/18127

  Regenerative braking · CPC title