Battery pack fuse monitoring and current limiting system

摘要

A battery pack monitoring system is provided that continually monitors the current at the fuse and, when the system determines that the fuse is close to its operating limit, limits battery pack current by limiting traction motor torque.

主权项

1. A method of limiting motor torque in an electric vehicle, said electric vehicle comprising an electrical system, said electrical system comprising a battery pack coupled to a motor, said method comprising:
measuring a battery pack current (i), wherein said battery pack current passes through a battery pack fuse; determining a characteristic of said electrical system, wherein said characteristic relates to a difference between said battery pack current and an operating limit of said battery pack fuse; determining a current limit based on said characteristic of said electrical system; determining a battery discharge current limit (Imax) and a battery charge current limit (Imin) from said current limit; setting a maximum motor discharge power (MPmax), wherein said MPmax is defined by MPmax=ImaxVdc, where Vdc corresponds to a battery pack voltage; setting a maximum motor charge power (MPmin), wherein said MPmin is defined by MPmin=IminVdc; calculating a motor efficiency (eff), wherein said motor efficiency is comprised of a plurality of power losses corresponding to motor losses and non-motor electrical system losses; and determining a first set of motor torque limits corresponding to positive rotor speeds and a second set of motor torque limits corresponding to negative rotor speeds, wherein said first and second sets of motor torque limits are based on said MPmax, said MPmin, said eff and a rotor speed (ω).