Electric power steering control system

An electric power steering system comprising:

• an electric motor for generating a steering assist force;
• and
• a control system for driving the electric motor on the basis of a steering torque applied to an operation member,
• the control system comprising:
• a target current determining circuit for generating a target current value according to the steering torque;
• a compensation value determining circuit for generating a compensation current value according to a time-based differential value of the steering torque;
• a waveform transforming circuit for performing a waveform transformation to convert the compensation current value generated by the compensation value determining circuit into a modified compensation value which sinusoidally change with time;
• a circuit for generating a control command value by superimposing the modified compensation value generated by the waveform transforming circuit on the target current value determined by the target current determining circuit;
• and
• a motor driving circuit for driving the electric motor on the basis of the control command value.