Vehicle mass and road grade based regenerative braking and anti-rollback
A method of controlling torque of an electric vehicle, including sensing a surface grade; determining an acceleration of the vehicle; determining an initial torque of the vehicle; estimating a weight of the vehicle based the surface grade, the acceleration, and the initial torque; converting the weight of the vehicle to a weight factor; and determining an output torque by applying the weight factor to the initial torque.
1. A method of controlling torque of an electric vehicle, the method comprising:
sensing a surface grade;
determining an acceleration rate of the vehicle;
determining an initial torque of the vehicle;
estimating a weight of the vehicle based on the surface grade, the determined acceleration rate, and the initial torque;
converting the weight of the vehicle to a weight factor;
determining an output torque by applying the weight factor to the initial torque; and
determining whether the vehicle is in a regenerative braking state or an anti-rollback state,
wherein the weight factor is a regenerative weight factor in the regenerative braking state and an anti-rollback weight factor in the anti-rollback state.
2. The method of claim 1 , wherein the regenerative weight factor and the anti-rollback weight factor are different.
3. The method of claim 1 , further comprising receiving a mass-estimation logic disable signal, and responsive to the mass-estimation logic disable signal, setting the output torque to the initial torque.
4. The method of claim 1 , further comprising receiving a mass-estimation logic disable signal, and responsive to the mass-estimation logic disable signal, setting the weight factor to 1.0.
5. The method of claim 1 , further comprising filtering the acceleration and the initial torque before estimating the weight.
6. The method of claim 5 , wherein filtering comprises applying Kalman filters to the acceleration and the initial torque.
7. The method of claim 1 , further comprising sensing a speed of a vehicle, wherein determining the acceleration includes converting the speed to an acceleration value.
8. The method of claim 1 , further comprising sensing a speed of a vehicle, wherein determining the acceleration includes converting the speed to an acceleration value.
9. The method of claim 8 , wherein generating a vehicle weight estimation is further based on a physics-based model of the vehicle, the physics-based model comprising at least aerodynamics, inertia, rolling resistance, and input torque values related to the vehicle.
10. The method of claim 1 , wherein the gain factor is a positive, real number.
11. The method of claim 1 , wherein determining the output torque comprises multiplying the weight factor to the initial torque.
12. A driveline controller for an electric vehicle, comprising:
weight estimation logic structured to implement a torque control method as in claim 1 .
13. An electric vehicle comprising:
a road grade sensor;
a speed sensor;
a motor-generator; and
the driveline controller as in claim 12 , the driveline controller operable to cause the motor-generator to generate the output torque.
14. The electric vehicle of claim 13 , wherein the driveline controller further comprises a vehicle dynamics model, the vehicle dynamics model containing values associated with vehicle torque, direction, aerodynamics, inertia, rolling resistance, and frictional losses.