Motor controller and method of controlling motor

摘要

When there is a change in required torque, the prior art technique may cause the undesirably low accuracy in the sensor-free determination of the electrical angle. A motor controller of the present invention has the following configuration to control the operation of a synchronous motor, in which multi-phase alternating currents flow through coils to rotate a rotor. The motor controller includes an electrical angle determination unit, which applies a voltage for determination to the coils and determines the electrical angle of the rotor in a sensor-free manner, based on the electric currents flowing in response to the applied voltage for determination. The motor controller also has a torque control unit that applies a voltage for torque output to the coils, corresponding to the required torque. An adjustment unit included in the motor controller adjusts the execution timings of the electrical angle determination unit and the torque control unit, so as to prevent the variation in electric current by the torque control unit from affecting the execution of the electrical angle determination unit. One possible procedure schedules the execution timings of the electrical angle determination unit and the torque control unit. Another possible procedure causes the execution of the electrical angle determination unit to wait according to a variation in required torque. This arrangement enables the electrical angle to be determined with a high accuracy even in the case of a torque variation.