| 摘要 |
PROBLEM TO BE SOLVED: To resolve a problem of decrease in electrical power that can be supplied to a motor which occurs when excitation is suspended to determine the position of a rotor.SOLUTION: This invention relates to a method of determining position of a rotor of a permanent-magnet motor. The method uses two schemes to determine the position of the rotor. A first scheme is used when the rotor rotates within a first speed range, the first scheme comprising: sequentially exciting and freewheeling a winding of the motor; measuring a parameter that depends on the rate of change of the current in the winding; and comparing the measured parameter against a threshold. It is determined that the rotor is at a predetermined position when the measured parameter is less than or greater than the threshold. A second scheme is used when the rotor rotates within a second speed range, the second scheme comprising: generating one signal having a voltage that is proportional to the voltage across the winding; generating another signal having a voltage that depends on the rate of change of the current in the winding; and comparing the voltages of the one signal and the another signal. It is determined that the rotor is at a predetermined position when the voltages of the two signals correspond. |
