Three-phase AC motor drive control device

A three-phase AC motor drive control device, wherein, when driving a three-phase AC motor by a three-phase alternating rectangular wave voltage that has been power-converted on the basis of a switching command set in accordance with one cycle of an electric angle acquired from a rotational position of a rotor of the three-phase AC motor, the control device feedback-controls the voltage phase of the three-phase alternating rectangular wave voltage on the basis of a torque deviation between a command torque value to the three-phase AC motor and an actual torque value of the three-phase AC motor, the control device comprising:

• a phase command calculating section, which executes torque feedback calculation on the basis of the torque deviation, acquires a phase command, which is an advanced angle amount/delayed angle amount of a phase to be corrected on the basis of the calculation result, and successively stores and updates the acquired phase command;
• and
• a pulse pattern output section, which, in order to generate the switching command, always outputs a pulse pattern that is obtained by phase-shifting, only by the amount corresponding to the phase command, a basic phase of the three-phase alternating rectangular wave voltage, the basic phase being uniquely determined for one cycle of the electric angle, while monitoring the rotational position,
• wherein
• the pulse pattern output section has a nonvolatile waveform memory in which pulse waveform groups, each of which corresponds to three phases and is derived from a pulse pattern corresponding to the basic phase, are stored in advance, the number of stored pulse waveform groups being in accordance with the resolution of the phase command and maximum advanced angle amount/delayed angle amount with respect to the basic phase;
• and
• the control device always selects and outputs, from the waveform memory all the time, the pulse waveform groups for three phases in which the monitored rotational position corresponds to the phase command.