Ac motor control device and air conditioning device

An AC motor control device, comprising:

• estimating circuitry calculate an estimated rotational velocity that is an estimate of a rotational velocity of an AC motor and an estimated rotational acceleration that is an estimate of a rotational acceleration of the AC motor;
• rotational velocity controlling circuitry to calculate, using the estimated rotational velocity, a basic torque to be output by the AC motor that is required for causing the rotational velocity of the AC motor to approach the target rotational velocity indicated by a velocity command, and output a basic torque command indicating the calculated basic torque;
• torque compensating circuitry to calculate, using the estimated rotational acceleration, a torque compensation value that is a compensation value for the basic torque that is required for suppressing a fluctuation of the rotational velocity of the AC motor, and output a torque compensation command indicating the calculated torque compensation value;
• compensation limiting circuitry to execute limitation processing for limiting the torque compensation value indicated by the torque compensation command, and output a limit-processed torque compensation command indicating a limit-processed torque compensation value obtained by the execution of the limitation processing on the torque compensation command;
• adding circuitry to add, to the basic torque indicated by the basic torque command, the limit-processed torque compensation value indicated by the limit-processed torque compensation command, and output a synthetic torque command indicating a synthetic torque obtained by the addition;
• and
• voltage instructing circuitry to output, to an inverter to supply electric power to the AC motor, a voltage command indicating a voltage required for outputting the synthetic torque indicated by the synthetic torque command, wherein
• in the limitation processing, the compensation limiting circuitry limits an amplitude of the torque compensation value that changes over time to be lower than or equal to a predetermined upper limit value,
• the upper limit value depends on a value of the target rotational velocity, and
• a first upper limit value that is the upper limit value for a value of the target rotational velocity within a first rotational velocity range is defined to be smaller than a second upper limit value that is the upper limit value for a value of the target rotational velocity within a second rotational velocity range indicating the rotational velocity lower than the first rotational velocity range.