Abstract: In an ?? coordinate system, vectors of currents flowing in three-phase AC motor are set in directions fixed relative to a zero vector current according to a voltage applied in six non-zero vector switching modes of an inverter. A current vector closest to a command current value is specified from those current vectors. Then, only a non-zero vector current when operating the inverter in the non-zero vector switching mode corresponding to the specified current vector is calculated.

Abstract: A motor control apparatus includes a calculator, a determinator, and a selector. The calculator calculates a zero vector current predicted to flow through a three-phase AC motor when an inverter operates in a first mode for applying no voltage to the motor. The determinator determines whether a difference between the zero vector current and a command current on a ?? stationary coordinate system falls within an allowable range. The selector selects the first mode as a switching mode of the inverter when the difference falls within the allowable range, and selects a second mode as the switching mode of the inverter upon determination that the difference falls outside the allowable range. The second mode corresponds to a non-zero current vector closest to the command current among six non-zero current vectors defined in fixed directions with respect to the zero vector current on the ?? stationary coordinate system.

Abstract: A motor control apparatus includes a calculator, a determinator, and a selector. The calculator calculates a zero vector current predicted to flow through a three-phase AC motor when an inverter operates in a first mode for applying no voltage to the motor. The determinator determines whether a difference between the zero vector current and a command current on a ?? stationary coordinate system falls within an allowable range. The selector selects the first mode as a switching mode of the inverter when the difference falls within the allowable range, and selects a second mode as the switching mode of the inverter upon determination that the difference falls outside the allowable range. The second mode corresponds to a non-zero current vector closest to the command current among six non-zero current vectors defined in fixed directions with respect to the zero vector current on the ?? stationary coordinate system.

Abstract: In an ?? coordinate system, vectors of currents flowing in three-phase AC motor are set in directions fixed relative to a zero vector current according to a voltage applied in six non-zero vector switching modes of an inverter. A current vector closest to a command current value is specified from those current vectors. Then, only a non-zero vector current when operating the inverter in the non-zero vector switching mode corresponding to the specified current vector is calculated.