Patent ID: 8228008

Claim:
A motor controlling apparatus for controlling a plurality of alternating-current motors, the motor controlling apparatus comprising: a direct-current voltage source; a plurality of inverters that are provided correspondingly to each of the alternating-current motors, and outputs an alternating-current voltage at a predetermined frequency obtained by converting a direct-current voltage supplied from the direct-current voltage source to each of the alternating-current motors; a contactor that opens and closes an output end of each of the inverters; a voltage detector that detects the direct-current voltage supplied to each of the inverters; a current detector that detects a current in each of the alternating-current motors; and a controller that outputs at least a control signal to the inverters based on a control command supplied externally, the voltage detected by the voltage detector, the current detected by the current detector, and a signal indicating conditions of rotations of the alternating-current motors, wherein the controller includes: a first common calculation unit having: a sequence processor that generates and outputs a first control signal that relates to generation of a torque command, based on a drive command signal input externally, and a protection detector that detects an abnormality in the alternating-current motors and the motor controlling apparatus, and generates a second control signal indicating the abnormality to cause the inverters to stop; a second common calculation unit having a basic torque command generator that generates and outputs a basic torque command that is common to the inverters based on the first control signal received from the first common calculation unit; an individual calculation unit that individually generates and outputs third control signals individually related to each of the inverters based on the basic torque command received from the second common calculation unit; and a common logic calculation unit that calculates and outputs a first gate signal for controlling switching of each of the inverters based on the second control signal received from the first common calculation unit and the third control signals received from a plurality of such individual calculation units, and is commonly provided to the individual calculation units so as to enable the first gate signals corresponding to each of the inverters to be controlled simultaneously.