Hitachi-johnson Controls Air Conditioning, Inc.

Koji Tsukii

Masahiro Tamura

Atsushi Okuyama

Kenji Tamura

Yoji Ogura

Tsutomu Kurokawa

Kazuhiro Ueta

An air conditioner is provided that reduces user discomfort due to vibrations and noises at a compressor, piping, and the like such as of an air conditioner. To achieve this, an air conditioner includes: a compressor () that has a motor () and a compression mechanism () driven by the motor (); a speed detector () that detects a rotation speed of the motor (); a drive mode controller () that controls a drive mode of the motor (); and refrigerant piping that is connected to the compression mechanism () and allows a refrigerant to flow therethrough, wherein the drive mode controller (), for stopping the motor (), decelerates the motor () to a rotation speed equal to or lower than a resonance frequency between the compression mechanism () and the refrigerant piping.

Air conditioner and motor controller

A DC power supply unit is provided that allows for improving efficiency and reducing harmonic currents. A DC power supply unit includes: a bridge rectification circuit having diodes and MOSFETs; a reactor that is arranged between the AC power supply and the bridge rectifier circuit; a smoothing capacitor that is connected to an output side of the bridge rectifier circuit and smoothes a voltage; and a converter control unit that executes, based on predetermined threshold values, a diode rectification control that uses diodes and parasitic diodes of the MOSFETs, a synchronous rectification control that switches the MOSFETs in synchronization with a polarity of the voltage of the AC power supply, a partial switching control that repeats partially short-circuiting the reactor multiple times in a half cycle of the AC power supply, or a fast switching control that short-circuits the reactor at a predetermined frequency over a full AC cycle.

DC power supply unit and air conditioner using same

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Tokyo, Japan

Koji Tsukii