Patent ID: 8847539

Claim:
A servomotor drive device comprising: a first converter having a plurality of first rectifier elements configured to convert an AC current from an AC power source into a DC current and to supply DC power to a first inverter configured to convert DC power into AC power; a regenerative resistor circuit connected in parallel to the first converter and having a first switching element and a regenerative resistor configured to consume regenerative energy generated during speed reduction of a servomotor connected in series to the first inverter and connected to a rotating shaft of a moving part of an industrial robot when the first switching element is in the on state; a first connection part configured to connect a second converter in parallel to the regenerative resistor circuit in an attachable and detachable manner; and a first control unit configured to control the on and off states of the first switching element, wherein the second converter has: a plurality of second rectifier elements configured to convert an AC current from an AC power source into a DC current and to supply DC power to the first inverter; second switching elements in the same number as that of the plurality of second rectifier elements, connected in parallel to the plurality of second rectifier elements, respectively; and a second control unit configured to return the regenerative energy to the AC power source side by bringing the second switching element into the on state when the second converter is connected to the first connection part.