Current detection device, motor control device, and electric power steering device

A current detection device comprising:

• a current detection unit configured to detect current flowing through a switching element of one arm of either an upper-side arm or a lower-side arm of a multiphase inverter on which PWM control is executed, based on a voltage drop of a resistor element connected in series to the switching element;
• a correction value calculation unit configured to calculate an offset correction value, based on a detection value of the current detected by the current detection unit in a period during which the switching element is off during the PWM control, and to hold and update the calculated offset correction value;
• and
• a correction unit configured to correct, by the offset correction value held by the correction value calculation unit, the detection value of the current detected by the current detection unit in a period during which the switching element is on,
• wherein the correction value calculation unit is configured to not update the offset correction value in a case where the switching element is the switching element of the lower-side arm and a duty ratio of the PWM control is equal to or less than a duty ratio lower limit value, or in a case where the switching element is the switching element of the upper-side arm and the duty ratio is equal to or greater than a duty ratio upper limit value, and
• in a case where the switching element is the switching element of the lower-side arm and the duty ratio is equal to or less than the duty ratio lower limit value in at least one phase of phases of the multiphase inverter, or in a case where the switching element is the switching element of the upper-side arm and the duty ratio is equal to or greater than the duty ratio upper limit value in at least one phase of the phases of the multiphase inverter, the correction value calculation unit is configured to not update the offset correction value in another phase of the phases of the multiphase inverter.