Control device of ac rotating machine and electric power steering device

A control device of an AC rotating machine estimating, as an estimated rotational position, a rotational position of an AC rotating machine having N sets of three-phase windings, where N is a natural number equal to or greater than 2,

• the control device comprising:
• a current detector that detects and outputs N sets of currents respectively flowing in N sets of three-phase windings;
• a controller that calculates and outputs respective N sets of voltage commands for the N sets of three-phase windings on the basis of a control command for the AC rotating machine and the N sets of currents input from the current detector;
• and
• a power converter that applies AC voltage to the N sets of three-phase windings on the basis of the input N sets of voltage commands, wherein
• the controller has
• a voltage sum calculator that calculates and outputs a voltage sum from the input N sets of voltage commands;
• a current sum calculator that calculates and outputs a current sum from the input N sets of currents;
• and
• a rotational position estimator that calculates the estimated rotational position on the basis of the input voltage sum and the input current sum.