Abstract: A ventilation device includes AC voltage estimation unit (32) for estimating an AC voltage, based on a DC voltage detected by voltage detection unit (30) and a current detected by current detection unit (20). Air volume computation unit (24) determines a rotation speed of a motor, based on the AC voltage estimated by AC voltage estimation unit (32) and a target air volume output from a target air volume computation unit.

Abstract: Between the lower stage in respective phases of inverter circuit and the negative potential side, shunt resistors are inserted for respective phases. The potential differences across shunt resistors occurring by current flowing through shunt resistors are amplified by amplifier unit. From the output of amplifier unit, current detecting unit detects current of each phase flowing through motor formed by a sensorless brushless DC motor. Rotation detecting unit calculates the rotation speed and position of motor based on the current detected by current detecting unit. This structure makes it possible to directly detect solely the current flowing through the windings of motor. Therefore, it becomes possible to accurately detect the current of the motor windings, and the ventilation device can maintain the ventilation air volume from a small air volume to a large air volume always at a constant value.

Abstract: A ventilation device includes AC voltage estimation unit (32) for estimating an AC voltage, based on a DC voltage detected by voltage detection unit (30) and a current detected by current detection unit (20). Air volume computation unit (24) determines a rotation speed of a motor, based on the AC voltage estimated by AC voltage estimation unit (32) and a target air volume output from a target air volume computation unit.

Abstract: Between the lower stage in respective phases of inverter circuit and the negative potential side, shunt resistors are inserted for respective phases. The potential differences across shunt resistors occurring by current flowing through shunt resistors are amplified by amplifier unit. From the output of amplifier unit, current detecting unit detects current of each phase flowing through motor formed by a sensorless brushless DC motor. Rotation detecting unit calculates the rotation speed and position of motor based on the current detected by current detecting unit. This structure makes it possible to directly detect solely the current flowing through the windings of motor. Therefore, it becomes possible to accurately detect the current of the motor windings, and the ventilation device can maintain the ventilation air volume from a small air volume to a large air volume always at a constant value.

Abstract: A heat exchange cooler capable of eliminating continuous radiation of high-frequency noise waves and reducing the man hour for the installation work, and a power circuit driving device used for it are provided. A commercial power transformer (311), which transforms commercial AC power (307) supplied from a heat generating element storing box to a specified range of voltage, is provided. Moreover, first relay (210) and second relay (212) are used for automatically switching a plurality of taps disposed at the coil of commercial power transformer (311) which keeps a wide range of commercial AC voltage from 200V to 250V in nominal voltage within a specified range of output voltage.

Abstract: A heat exchange cooler capable of eliminating continuous radiation of high-frequency noise waves and reducing the man hour for the installation work, and a power circuit driving device used for it are provided. A commercial power transformer (311), which transforms commercial AC power (307) supplied from a heat generating element storing box to a specified range of voltage, is provided. Moreover, first relay (210) and second relay (212) are used for automatically switching a plurality of taps disposed at the coil of commercial power transformer (311) which keeps a wide range of commercial AC voltage from 200V to 250V in nominal voltage within a specified range of output voltage.

Abstract: A heat exchange cooler capable of eliminating continuous radiation of high-frequency noise waves and reducing the man hour for the installation work, and a power circuit driving device used for it are provided. A commercial power transformer (311), which transforms commercial AC power (307) supplied from a heat generating element storing box to a specified range of voltage, is provided. Moreover, first relay (210) and second relay (212) are used for automatically switching a plurality of taps disposed at the coil of commercial power transformer (311) which keeps a wide range of commercial AC voltage from 200V to 250V in nominal voltage within a specified range of output voltage.