Abstract: A compressor includes a motor driven by a controller and having a rotor and a stator, a compressing unit driven by the motor in a hermetic container in which refrigerant is filled. Driving the motor at a low rpm, the controller practices a feedback control which determines a timing of turning on/off switching elements based on a signal detecting a position of the rotor, and when the motor is driven at a high rpm, the controller practices an open-loop control which outputs a given frequency and drives the motor synchronizing with the given frequency. This structure achieves a compressor working with a fewer noises in PWM driving.

Abstract: A rectangular wave or a waveform similar to the rectangular wave is output with an conductive angle no less than 120° but no more than 150° during low-speed operation, but output a rectangular wave, a sine wave or a waveform similar to them with an conductive angle no less than 130° but under 180° by changing the frequency only while maintaining the PWM duty constant at high-speed operation, making it possible to realize high-efficiency and low-noise operation at low-speed operation, secure stable high speed, and prevent peak current of effective current because the current waveform also comes closer to sine wave.

Abstract: A rectangular wave or a waveform similar to the rectangular wave is output with an conductive angle no less than 120° but no more than 150° during low-speed operation, but output a rectangular wave, a sine wave or a waveform similar to them with an conductive angle no less than 130° but under 180° by changing the frequency only while maintaining the PWM duty constant at high-speed operation, making it possible to realize high-efficiency and low-noise operation at low-speed operation, secure stable high speed, and prevent peak current of effective current because the current waveform also comes closer to sine wave.

Abstract: A compressor includes a motor driven by a controller and having a rotor and a stator, a compressing unit driven by the motor in a hermetic container in which refrigerant is filled. Driving the motor at a low rpm, the controller practices a feedback control which determines a timing of turning on/off switching elements based on a signal detecting a position of the rotor, and when the motor is driven at a high rpm, the controller practices an open-loop control which outputs a given frequency and drives the motor synchronizing with the given frequency. This structure achieves a compressor working with a fewer noises in PWM driving.