AC motor drive control device

An AC motor drive control device comprising:

• an inverter, including a plurality of switching elements subjected to on-off control, for converting a DC voltage to an AC voltage with a desired frequency to drive an AC motor;
• a motor side switching unit connected between the inverter and the AC motor;
• a switching operation beforehand detection unit for detecting a switching operation of the motor side switching unit prior to contact or detach of main contacts and outputting a switching operation beforehand detection signal;
• and
• a control unit for performing the on-off control for the plurality of switching elements, the control unit having a discrepancy determination unit for determining a difference between the switching operation beforehand detection signal and a switching command of the motor side switching unit, wherein
• the control unit controls the inverter when a discrepancy is determined at the discrepancy determination unit.

An AC motor drive control device comprising:

• an inverter, including a plurality of switching elements subjected to on-off control, for converting a DC voltage to an AC voltage with a desired frequency to drive an AC motor;
• a motor side switching unit connected between the inverter and the AC motor and having a vacuum contact;
• a switching operation beforehand detection unit for detecting a switching operation of the motor side switching unit prior to contact or detach of main contacts and outputting a switching operation beforehand detection signal;
• and
• a control unit for performing the on-off control for the plurality of switching elements, controlling the inverter so as to prevent a voltage changing in a pulsed form from being superimposed between the main contacts of the motor side switching unit based on the switching operation beforehand detection signal, and controlling all of the plurality of switching elements to an OFF state after passage of a predetermined period of time.

An AC motor drive control device comprising:

• an inverter, including a plurality of switching elements subjected to on-off control, for converting a DC voltage to an AC voltage with a desired frequency to drive an AC motor;
• a motor side switching unit connected between the inverter and the AC motor;
• a switching operation beforehand detection unit for detecting a switching operation of the motor side switching unit prior to contact or detach of main contacts based on a voltage applied to an operating electromagnet for operating switching of a movable contact in the motor side switching unit, an excitation current in the operating electromagnet, or a displaced amount of a movable unit in the motor side switching unit, and outputting a switching operation beforehand detection signal;
• and
• a control unit having an inverter control unit for performing the on-off control for the plurality of switching elements and controlling the inverter based on the switching operation beforehand detection signal.