| 摘要 |
PROBLEM TO BE SOLVED: To exactly estimate the positions of the magnetic poles of a rotor by leading out driving signals which switch the outputs of the switching elements of the upper arm of an inverter circuit when the time corresponding to a specific electrical angle has elapsed after terminal voltages disappear. SOLUTION: A control circuit 4 switches the outputs of the switching elements J4 , J5 , and J6 of the lower arm of an inverter circuit 1 when the terminal voltages Va , Vb , and Vc of stator windings disappear on the basis of the output of a rotor position detecting section 3 when the windings are not energized and released. When the time corresponding to an electrical angle of 60 deg. has elapsed after the voltages Va , Vb , and Vc disappear, the circuit 4 leads out driving signals which switch the outputs of the switching elements J1 , J2 , and J3 of the upper arm of the circuit 1. Therefore, the positions of the magnetic poles of a rotor can be estimated exactly and commutation can be performed at exact timing. |
