IMPEDANCE MATCHING DEVICE

PROBLEM TO BE SOLVED: To provide an impedance matching device that makes it possible to know maintenance timing beforehand. SOLUTION: The impedance matching device includes: variable capacitors VC1, VC2; an operating mechanism that operates the operating shafts of the variable capacitors using motors 7a, 7b as driving sources; a target position setting unit 9 for setting the target position of the operating shaft of each variable capacitor; a motor control unit 13 that controls the motor so that the detected position of the operating shaft of each variable capacitor agrees with a set target position; an anomaly determination unit 11 that determines an anomaly when a deviation between the target position of each operating shaft and its present position exceeds a predetermined value; an output torque setting unit 12 that sets the output torque of each motor to an initial torque until the first anomaly determination is made by the anomaly determination unit and sets the output torque of each motor to a torque after anomaly detection which is larger than the initial torque when the first anomaly determination is made; and a motor drive unit 10 that drives each motor so that the output torque of the motor becomes equal to the torque set with the output torque setting unit. COPYRIGHT: (C)2010,JPO&INPIT