| 摘要 |
PROBLEM TO BE SOLVED: To drive a motor at an optimum efficiency point for a load by a method wherein a ratio of a current detection value to an actual revolution is obtained to detect a load torque and an optimum phase shift is performed in accordance with the detected load torque. SOLUTION: The actual revolution of a rotor is calculated by a revolution calculating block 7a from the output of a rotor position detecting means 6. A load torque is calculated by a load torque calculating block 7b in which the output ratio between the rotor position detecting means 6 and a current detector 5. A phase shift value corresponding to the load torque is obtained by a phase shift value calculating block 7c. Then, when the logic calculation is performed in a logic calculating block 7d, the phase shift value is added and, as a result, the phase of the driving signal of a DC brushless motor is shifted, so that the motor is driven with the optimum phase for the load torque. |
