Control apparatus for electric vehicle, control system for electric vehicle, and control method for electric vehicle

A control method for an electric vehicle including a plurality of axles and motors configured to receive supply of power from a power source and provide a torque to the plurality of axles, the control method comprising:

• calculating, as a first power limit value calculation, a power limit value of each of the motors that is used when the power is supplied to the motors, based on a power limit value of the power source;
• and
• calculating, as a first torque limit value calculation, a first torque limit value, which is a torque limit value of each of the motors, based on the power limit value of each of the motors;
• calculating, as a requested torque calculation, a requested torque of the electric vehicle;
• calculating, as a requested torque distribution ratio calculation, a distribution ratio at which the requested torque is distributed to each of the plurality of axles;
• calculating, as a first torque instruction value calculation, a first torque instruction value of each of the motors that is equal to or smaller than the first torque limit value and is within the distribution ratio,
• calculating, as a second torque instruction value calculation, a second torque instruction value, within a range of values that allow a sum of the first torque instruction values of individual motors not to exceed the requested torque, the second torque instruction value being a redistributed torque applied to a motor and having a value that corresponds to the first torque instruction value and being lower than the first torque limit value, when the sum of the first torque instruction values of the individual motors is smaller than the requested torque;
• and
• calculating, as a second power limit value calculation, a second lower limit value resulting from distributing extra power acquired by subtracting actual power consumption from the power limit value of one motor out of the individual motors to the power limit value of the other motor.

A control system for an electric vehicle, the control system comprising:

• a power source;
• motors configured to receive supply of power from the power source and provide a torque to a plurality of axles of the electric vehicle;
• and
• a control unit configured to control the power source and the motors,
• wherein the control unit includes
• a first power limit value calculation portion configured to calculate a power limit value of each of the motors that is used when the power is supplied to the motors, based on a power limit value of the power source;
• a first torque limit value calculation portion configured to calculate a first torque limit value, which is a torque limit value of each of the motors, based on the power limit value of each of the motors,
• a requested torque calculation portion configured to calculate a requested torque of the electric vehicle;
• a requested torque distribution ratio calculation portion configured to calculate a distribution ratio at which the requested torque is distributed to each of the plurality of axles;
• a first torque instruction value calculation portion configured to calculate a first torque instruction value of each of the motors that is equal to or smaller than the first torque limit value and is within the distribution ratio;
• a second torque instruction value calculation portion configured to calculate a second torque instruction value, within a range of values that allow a sum of the first torque instruction values of individual motors not to exceed the requested torque, the second torque instruction value being a redistributed torque applied to a motor having a value that corresponds to the first torque instruction value and being lower than the first torque limit value, when the sum of the first torque instruction values of the individual motors is smaller than the requested torque, and
• a second power limit value calculation portion configured to calculate a second power limit value resulting from distributing extra power acquired by subtracting actual power consumption from the power limit value of one motor out of the individual motors to the power limit value of the other motor.