Machine learning device, servo motor controller, servo motor control system, and machine learning method

A machine learning device that performs machine learning with respect to a servo motor controller configured to convert a three-phase current to a two-phase current of the d- and q-phases to perform current control on a servo motor, the machine learning device comprising:

• a state information acquisition unit configured to acquire, from the servo motor controller, state information including at least velocity or a velocity command, reactive current, and an effective current command and effective current or a voltage command, by causing the servo motor controller to execute a predetermined program;
• an action information output unit configured to output action information including a reactive current command to the servo motor controller;
• a reward output unit configured to output a value of a reward of reinforcement learning based on the voltage command or the effective current command and the effective current included in the state information;
• and
• a value function updating unit configured to update a value function on the basis of the value of the reward output by the reward output unit, the state information, and the action information.