| 摘要 |
PROBLEM TO BE SOLVED: To accurately calculate a variation rate of a terminal voltage during a high speed rotation by calculating variation rate depending on the number of rotations of the motor and determining a commutation time depending on the calculated variation rate. SOLUTION: A selector 3 is provided to select one phase of the non-feeding phase among a DC power source 1, an inverter 2 and 3-phase coil. An analog value of terminal voltage of the selected terminal is ADD-converted 4 and the converted digital voltage is input to a controller 5. The effective induced voltage information from a coil is only an induced voltage from the coil which is not fed of one of three phases. A control means 5 inputs a detected value of the induced voltage, obtains a variation rate for the time of voltage, namely gradient of voltage and the time until the target voltage value is obtained to control a switching element of the inverter 2. Thereby, the motor can be controlled with higher accuracy from the low to the high speed. |
