| 摘要 |
PROBLEM TO BE SOLVED: To attain optimum timing of energization switching by advancing an intersection (zero cross point) of an inductive voltage waveform and reference voltage in a controlling method for brushelss motor. SOLUTION: For the detection of a rotor position, an inductive voltage waveform occurring in an non-energized phase of a brushless motor 3 is obtained in a resistor circuit 6 for comparison with reference voltage, thereby detecting a zero cross point. A prescribed voltage kV obtained by dividing DC voltage 1 with two resistors R5, R6 is halved in r1 and r2 to obtain a reference voltage (mid point). The resistor r1 is parallel-connected with the three-state gate 10b of a non-reversal enable terminal, and the resistor r2 is parallel-connected with the three-state gate 10c of a reversal enable terminal. Each of the enable terminals is inputted with the same pulse of a constant period, the ON width or the OFF width of the pulse for one turn is changed and the reference voltage is increased or decreased, thereby changing the detection timing of the comparative results (zero cross point) in a comparing circuit 8. |
