Vehicular steering control apparatus and method

A vehicular steering control apparatus, comprising:

• a steering mechanism configured to steer steerable wheels of a vehicle according to a steering force;
• an electric motor configured to be drivingly controlled to provide the steering force for the steering mechanism;
• a steering quantity calculation section configured to calculate a manipulated variable of the electric motor;
• a PWM control section configured to generate a PWM control signal to drive the electric motor on a basis of the manipulated variable of the electric motor;
• an inverter configured to supply an electric power to the electric motor according to switching operations thereof based on the PWM control signal;
• and
• a carrier frequency control section configured to control a carrier frequency of the PWM control signal,
• wherein the carrier frequency control section is configured to set the carrier frequency to at least two predetermined set frequencies in accordance with at least one of a driving state of the electric motor and a traveling state of the vehicle, one of the predetermined set frequencies being set to reduce noises in the inverter and the other of the predetermined set frequencies being set to reduce a switching loss in the inverter.