| 摘要 |
PROBLEM TO BE SOLVED: To obtain a control method in which the output current of an inverter is lowered at a maximum speed of rotation without lowering the terminal voltage of a motor at a maximum speed of rotation, in which a copper loss due to a current is reduced and in which heat generation and efficiency of the motor are enhanced. SOLUTION: In a vector control method for a synchronous motor which requires a fixed output ratio of 1:(n) [where (n) represents a base speed ratio], the maximum speed of rotation of the synchronous motor is designated as Ntop, and its base speed of rotation Nbase is expressed as Nbase=Ntop/(n). At this time, the rotational speed N of the synchronous motor is divided into two control ranges, i.e., a range of 0<=N< Nbase and a range of Nbase<=N<=Ntop. In the range of Nbase<=N<=Ntop, the relationship between a q-axis current Iq1 and a d-axis current Id1 which are required for ensuring a required output and which flows in conformity with a torque command Tref (5) is set at Iq=Iq1 =Iqmax×(Tref/100)×(Nbase/N) [where Iqmax represents a current Iq in a rating of 100%] and Id1 d=Kd1×Iq1 [where Kd1 represents a proportionality constant]. A d-axis current Id0 which is used to suppress the terminal voltage of the synchronous motor is set at Id0 =Kd0 ×(N-Nbase)/N [where Kd0 represents a proportionality constant], thus obtaining Id=Id0 +Id1 . |
