POWER CONVERSION DEVICE, DRIVE CONTROL SYSTEM, MACHINE LEARNING DEVICE, AND MOTOR MONITORING METHOD

This power conversion device is provided with a main circuit unit, a control unit (12), a current sensor, and a half-wave rectifier. The control unit (12) is provided with current frequency calculation units (42, 51) and monitoring units (43, 52). The current frequency calculation units (42, 51) calculate current frequencies (megac1, megac2) on the basis of the rise timing and/or the fall timing of a current detection signal, which is the current detection signal that has been half-wave rectified by the half-wave rectifier. The monitoring units (43, 52) monitor the motor speed on the basis of the current frequencies (megac1, megac2) calculated by the current frequency calculation units (42, 51). 电力转换装置具有主电路部、控制部(12)、电流传感器和半波整流部。控制部(12)具有电流频率计算部(42、51)和监视部(43、52)。电流频率计算部(42、51)基于由半波整流部进行了半波整流的电流检测信号即电流检测信号的上升定时以及下降定时的至少任一者，对电流频率(ωc1、ωc2)进行计算。监视部(43、52)基于由电流频率计算部(42、51)计算出的电流频率(ωc1、ωc2)，对电动机的速度进行监视。