To return power generated when a motor decelerates to a power supply, by turning on or off the transistor of a converter according to the phase and output voltage of an AC power supply by a CPU at a DC power supply part.
A DC power supply part 11 uses a three-phase AC power supply 10 as a power supply and is connected to a converter 13 via a contactor 12 for safety in the power supply, and a total of six transistors T1-T6 that are connected pair by pair while a connection terminal is inverted for each phase are provided at the converter 13. Then, the transistors T1-T6 are turned on or off by a gate drive circuit 14, and the on/off of the gate drive circuit 14 is controlled by a CPU 15, thus returning power that is generated when motors 6 and 7 decelerate to the power supply side, and reducing consumption power without consuming power by allowing the power to flow to a regeneration resistor 22.
TANAKA YOICHI
HAYASHI TOMOHISA
FUNABASHI YOSHIFUMI
TOMITA AKINOBU
MATSUZAKA TAKEHIKO
