Abstract: A method and apparatus for controlling a brushless DC motor which has a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor. A specified reference voltage is compared with the stator winding terminal voltages for each phase. The rotor position is detected from the output of these comparison circuits based on the induced voltages generated in the stator windings which are not conducting when the motor is rotated. The stator windings which conduct current are controlled in response. Furthermore, a specific conduction pattern is supplied to each stator winding when the rotor is stopped, and a reference output determined for the conduction pattern is compared with the output of the comparison circuits when the stator windings are conducting. Abnormalities are detected based on the comparison results of the comparison circuit.

Abstract: A method and apparatus for controlling a brushless DC motor which has a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor. A specified reference voltage is compared with the stator winding terminal voltages for each phase. The rotor position is detected from the output of these comparison circuits based on the induced voltages generated in the stator windings which are not conducting when the motor is rotated. The stator windings which conduct current are controlled in response. Furthermore, a specific conduction pattern is supplied to each stator winding when the rotor is stopped, and a reference output determined for the conduction pattern is compared with the output of the comparison circuits when the stator windings are conducting. Abnormalities are detected based on the comparison results of the comparison circuit.

Abstract: The position where an indoor unit is actually installed is manually instructed by an installation position confirmation element. A temperature correction value selector selects and outputs, from a Table prepared in advance, a temperature correction value (.DELTA.T.sub.s) in dependency upon the installation position confirmed by the installation position confirmation element in order to compensate a temperature difference which can exist between a temperature at a position to be mainly air-conditioned of a room and a temperature at the position where the indoor unit is installed, i.e., at the position where a room temperature is sensed. Thus, a set temperature (T.sub.s), a room temperature (T.sub.a), or a difference (T.sub.s -T.sub.a) therebetween is corrected by the temperature correction value (.DELTA.T.sub.s).

Abstract: The load torque of a compressor for circulating refrigerant in a refrigerating cycle changes with the rotational position of the shaft of the compressor, and the phase difference between the primary current and voltage of an induction motor for driving the compressor changes with the load torque. Taking the above facts into consideration, in turning off the compressor driven by the induction motor, which is powered by a fixed frequency AC power source, the shaft position of the compressor is detected in accordance with the phase difference, and the current of the motor is turned off at the timing of a particular phase difference when the load torque becomes minimum, thus reducing vibration when the compressor is stopped.