CONTROLLER AND CONTROL PROGRAM OF MOTOR IN CONSTRUCTION MACHINE

PROBLEM TO BE SOLVED: To accurately calculate a temperature in a switching element, and timely protect the switching element against a thermal breakdown even if a motor is repetitively operated between a lock state and a rotational state. SOLUTION: It determines whether the PM motor is in the lock state or the rotational state. If it determines that the PM motor is in the lock state, a current temperature difference Tbjn (=fn(W)) between a junction and a base is sequentially calculated based on a time t during the lock state and a previous temperature difference between the junction and the base Tbjn-1. If it determines that the PM motor is in the rotational state, the current temperature difference Tbjn (=gn(W)) between the junction and the base is sequentially calculated based on a time t during the rotational state and the previous temperature difference between the junction and the base Tbjn-1. COPYRIGHT: (C)2007,JPO&INPIT