초록 ▼

The conventional technique can not detect the electrical angle of a synchronous motor in a sensor-less manner when a high torque is required under the condition of a low-speed operation of the motor. The direction that passes through the axis of rotation of the motor and causes a magnetic flux to pa

The conventional technique can not detect the electrical angle of a synchronous motor in a sensor-less manner when a high torque is required under the condition of a low-speed operation of the motor. The direction that passes through the axis of rotation of the motor and causes a magnetic flux to pass through a permanent magnet is defined as a d axis, whereas the direction that is electrically perpendicular to the d axis in the plane of rotation of the motor is defined as a q axis. In the case where the motor is required to output a high torque, the technique of the present invention applies a predetermined detection voltage to the q axis and determines the electrical angle based on the ratio of electric currents flowing through the d axis and the q axis. Application of a negative voltage to the q axis relieves magnetic saturation occurring on the q axis under a high torque condition and thereby allows detection of the electrical angle. When a positive voltage is applied to the q axis, on the other hand, the technique of the present invention refers to a table which is stored in advance to represent the one-to-one mapping of the electrical angle to the electric current flowing through the q axis, and thereby determines the electrical angle.

대표청구항 ▼

[ What is claimed is:] [1.] In a synchronous motor that rotates a rotor through an interaction between a magnetic field occurring when multi-phase alternating currents are flown through windings and a magnetic field produced by permanent magnets, an electrical angle detection apparatus that detects

[ What is claimed is:] [1.] In a synchronous motor that rotates a rotor through an interaction between a magnetic field occurring when multi-phase alternating currents are flown through windings and a magnetic field produced by permanent magnets, an electrical angle detection apparatus that detects an electrical angle, the electrical angle defining a d-axis direction, which passes through a center of rotation of said rotor and goes along the magnetic field produced by said permanent magnets, and a q-axis direction, which is electrically perpendicular to said d-axis direction in a plane of rotation of said rotor, said electrical angle detection apparatus comprising:a torque voltage controller that applies a torque voltage to said windings, said torque voltage being applied corresponding to a torque command value to be output by said synchronous motor;a detection voltage controller that applies a predetermined detection voltage in a first direction for a predetermined application time period to be superposed upon said torque voltage, when said torque command value is present within a predetermined range, which includes a specific torque command value that causes magnetic saturation of said windings by application of said torque voltage;an electric current detection unit that detects variations in electric currents flowing in a second direction, which is estimated as said d-axis direction, and said first direction, which is estimated as said q-axis direction, corresponding to said superposed detection voltage; andan electrical angle computation unit that calculates the electrical angle of said synchronous motor, based on the variations in electric currents detected by said electric current detection sensor.