Abstract: AC power supply is converted to DC by a rectifier circuit. The DC is stepped up by a step-up chopper circuit. The output of the step-up chopper circuit is smoothed by a smoothing circuit. The output of the smoothing circuit is input to an inverter via a current detecting circuit and a voltage detecting circuit. A synchronous motor is connected to the inverter. When the speed of the synchronous motor is judged to be in a high speed region based on the output signal of the voltage detecting circuit, the first speed control apparatus operates the interrupting control of the switching element of the step-up chopper circuit in such a manner that a deviation speed between an instruction speed signal to the motor and the detected speed of the motor reaches to zero.

Abstract: A control system for brushless DC motors detects counter electromotive force voltages induced in motor windings and produces rotor position detection signals from the counter electromotive force voltages. The maximum value of an input DC current to a motor drive circuit is held and the phase of the rotor position detection signals is changed in accordance with the held value of the input DC current to prevent the phase of the position detection signals from varying with the load on the brushless DC motor.

Abstract: An air conditioner including a room temperature detector, a room temperature adjuster and a controller is disclosed which is provided with a photodetector, and in which the temperature set in the room temperature adjuster is changed on the basis of the illuminance detected by the photodetector, and a signal for controlling a compressor is generated by the controller in accordance with the temperature thus changed.

Abstract: A room air conditioner in which the interior of a cabinet is divided into an indoor portion and an outdoor portion by a partition plate having a non-vertical section, and a fan motor is supported in the outdoor portion in such a manner that its rotary shaft is disposed perpendicular to the bottom of the cabinet and penetrates the partition plate at one end thereof to extend into the indoor portion. A first centrifugal fan is mounted at one end of the rotary shaft of the fan motor while a second Silocco fan is mounted at the other end thereof disposed in the outdoor portion.