Hitachi, Ltd.

Kouji Katou

Yasuo Notohara

Yukio Kawabata

Yuhachi Takakura

Makoto Ishii

Hiroshi Shinozaki

Atsushi Okuyama

Hiroo Nakamura

Toru Inoue

Minoru Makita

Motoo Morimoto

Toyomitsu Wakui

Hideki Terauchi

Kenji Tamura

Kisasu Kaneko

Masayuki Iwasaki

Shoji Takaku

For detecting commutation timing of an inverter when operating a DC brushless motor under a starting thereof or a light load condition, with certainty, a micro-computer generates driving signals so as to drive switching elements of the inverter by PWM signals of those driving signals, in a predetermined order by every turn-on interval, thereby supplying driving current to the DC brushless motor, wherein a timing for exchange between the turn-on intervals (i.e., the commutation timing) is detected by detection of level of magnetic pole position detecting signals upon a basis of the PWM signals. Here, the minimum ON time of the PWM signals is set at a time being detectable in the level of the magnetic pole position detecting signals, however the frequency of the PWM signals is lowered when the DC brushless motor is operated in starting or under a light load condition, so as to make duty ratio of the PWM signals fit to the operation in the starting or under the light load condition, thereby enabling to ensure the minimum ON time of the PWM signals.

DC current brushless motor driving apparatus and air conditioner with using thereof

A motor drive apparatus and an air-conditioner using the motor control apparatus has a feature which allows it to gradually increase a dc voltage value to a predetermined value when starting the switching operation of a chopper circuit by dc voltage control thereof, and when stopping the switching operation of the chopper circuit to be able to gradually decrease the dc voltage value to a predetermined value. Further, the dc voltage command value is adjusted so as to make it possible to maintain a preferred value of dc voltage. Thereby, fluctuation in the number of revolutions of the motor can be prevented even if the converter is started or stopped while the motor is operating, thereby allowing the motor drive apparatus and air-conditioner using the motor control apparatus of the invention to be operated at their maximum capacities.

PWM/PAM control mode switching type motor control apparatus, and motor

For achieving an air conditioner being applicable to various a-c source voltages in common and operative with high power factor by suppressing generation of high harmonics, an a-c source voltage from an a-c electric power source 1 is rectified in full-wave by a rectifier 2, and a d-c source voltage Ed of an inverter 13 is obtained by being charged in a condenser 5. Here, there are a-c source voltages of 100 V and 200 V, and a divided voltage Ed1 of the d-c voltage of the condenser 5 is selected when the a-c source voltage is 100 V, a divided voltage Ed2 (here, Ed1&gt;Ed1) of the d-c voltage of the condenser 5 is selected when the a-c source voltage is 200 V, respectively by an exchange switch 18, and is used as a d-c voltage Ed' for controlling on and off of a switch element 6. Though the d-c source voltage Ed differs depending on the a-c source voltage of 100 V or 200 V, it is possible to set the d-c source voltage Ed at a voltage value for operating the inverter 13 with low loss and high efficiency, for each one of the a-c source voltages, by setting a ratio of the voltage division appropriately.

Air conditioner

Growing community of inventors

Ohiramachi, Japan

Kouji Katou