Patent ID: 8129928

Claim:
A power branching system for driving a plurality of linear motors synchronously by use of a single servo driver, the linear motors being connected to a rigid body, the power branching system comprising: U-phase, V-phase and W-phase power lines branched at some midpoint to connect the plural linear motors to the servo driver; a plurality of U-phase current sensors and a plurality of V-phase current sensors provided at branched U-phase power lines and branched V-phase power lines, respectively, for detecting U-phase and V-phase currents supplied to the respective linear motors; controlling means for receiving data of the U-phase currents detected by the U-phase current sensors, determining whether or not the U-phase currents are balanced and generating an alarm signal when the U-phase currents are unbalanced, and also for receiving data of the V-phase currents detected by the V-phase current sensors, determining whether or not the V-phase currents are balanced and generating an alarm signal when the V-phase currents are unbalanced; and the servo driver having a power converter, such as a voltage-type PWM inverter, for supplying power in a suitable manner to control the linear motors.