Power dissipating torque controller
AssigneeVolvo Car Corporation
InventorsLars JOHANSSON, Karl KLANG, Torbjorn THIRINGER
Life of this patent
Estimating the term…
Abstract
A method and a system are described for controlling power dissipation in an electric drive system for a hybrid electrical vehicle including determining the stator current of an electrical machine providing a maximum achievable power dissipation in the electrical drive system and determining a maximum available braking torque of an electrical machine.
Claims15
A method for controlling power dissipation in an electric drive system for a hybrid electrical vehicle having a gear set or a gear box, an electrical machine connected to an axle of the gear set or gear box, a rechargeable battery operatively connected to the electrical machine, and a control unit configured to control the gear box and the electrical machine, the method comprising:
- determining a maximum available braking torque of the electrical machine for a given set of operating conditions based on a maximum power that the battery can receive and total normal power losses in the electric drive system;
- determining a stator current providing a maximum achievable power dissipation in the electrical drive system for a certain shaft torque value;
- receiving a requested braking torque for the electrical machine, lower than or equal to the maximum available braking torque, or receiving a requested power dissipation lower than or equal to a maximum achievable power dissipation in the electrical drive system;
- if the requested braking torque is equal to or lower than a torque required for providing a power corresponding to a sum of the maximum power that the battery can receive and the total normal power losses, providing the requested braking torque by providing power to the battery corresponding to a difference between the requested braking torque and the total normal power losses;
- if the requested braking torque exceeds the torque required for providing a power corresponding to the sum of the maximum power that the battery can receive and the total normal power losses, determining a stator current of the electrical machine that will dissipate an additional power needed while achieving a required braking torque;
- and
- if a power dissipation is requested, determining a stator current resulting in the requested power dissipation.
A control system for controlling power dissipation in an electric drive system for a hybrid electrical vehicle having a gear set or a gear box, an electrical machine connected to an axle of the gear set or gear box, and a rechargeable battery operatively connected to the electrical machine via an inverter, the control system comprising:
- a control unit configured to control the gear box and the electrical machine, wherein the control unit is configured to
- determine a maximum available braking torque of the electrical machine for a given set of operating conditions based on a maximum power that the battery can receive and total normal power losses in the electric drive system;
- determine a stator current providing a maximum achievable power dissipation in the electrical drive system for a certain shaft torque value;
- receive a requested braking torque for the electrical machine, lower than or equal to a maximum available braking torque, or receive a requested power dissipation lower than or equal to the maximum achievable power dissipation;
- if a requested braking torque is equal to or lower than a torque required for providing a power corresponding to a sum of the maximum power that the battery can receive and the total normal power losses, provide the requested braking torque by providing power to the battery corresponding to a difference between the requested braking torque and the total normal power losses;
- if the required braking torque exceeds the torque required for providing a power corresponding to the sum of the maximum power that the battery can receive and the total normal power losses, determine a stator current of the electrical machine that will dissipate an additional power needed while still achieving a required braking torque;
- and
- if a power dissipation is requested, determine a stator current resulting in the requested power dissipation.
Dependencies are inferred from the claim text.