Minebea Mitsumi Inc.

Minebea Company, Limited

Toyota Boshoku Kabushiki Kaisha

Tetsuya Seki

Seiya Fujimoto

Shigeki Miyaji

Kei Yamazaki

Kiyohisa Nara

Takayuki Matsui

Masaaki Matsubara

Wataru Nogamida

Atsushi Tsuzaki

Hiroshi Murahata

Yuya Makino

Satoshi Hatahara

Yuki Kadono

In order to suppress high-frequency noise in micro-step driving of a stepping motor, a motor control device () includes an H bridge circuit () and control means for driving a switching element of the H bridge circuit () with a PWM signal and for setting a charge mode, a fast attenuation mode, or a slow attenuation mode for a motor coil. In a range from an electrical angle where the reference current value starts descending to an electrical angle of +52&#xb0;, the control means switches the H bridge circuit () every PWM cycle to the charge mode and then to the slow attenuation mode. In a range exceeding +52&#xb0; and to +90 degrees where the reference current value starts ascending, the control means switches the H bridge circuit () every PWM cycle to the charge mode and, if the motor current exceeds the reference current value, then the control means switches it to the fast attenuation mode and further to the slow attenuation mode.

Motor current control device and motor current control method

A centrifugal fan that is light in weight and has a structure that restrains vibration are provided. The centrifugal fan includes a resin upper casing, a resin lower casing, an impeller, a motor, and a circuit board. The impeller, the motor and the circuit board are housed between the resin upper casing and the resin lower casing. Radial ribs and a concentric ribs for reinforcing are formed at a bottom surface of a concave part of the lower casing. Resin pins are provided in a standing manner at these rib parts, and the circuit board is fixed to the lower casing by the resin pins.

Centrifugal fan

A motor drive controller includes: a control circuit that controls an AC current flowing in a motor; a frequency modulation unit that frequency-modulates a speed of the motor when the motor is driven at a predetermined speed; and a current effective value controller that decreases an effective value of the AC current flowing in the motor as the speed of the motor modulated by the frequency modulation unit becomes closer to a resonant frequency of the motor.

Motor drive controller and method for controlling motor

A motor drive controller capable of taking measures against vibration or noise of a motor is provided. The motor drive controller configured to drive a stepping motor in microstepping mode controls the number of PWM (Pulse Width Modulation) cycles contained in one microstep cycle. More specifically, the number of PWM cycles contained in one microstep cycle is controlled so that a vibration contained in a current waveform determined by the number of PWM cycles contained in one microstep cycle does not approximate the natural frequency of the stepping motor.

Motor drive controller, control method for motor drive controller, control program for motor drive controller, and method for determining number of divisions of basic step angle

A centrifugal fan includes: a casing including an upper casing, a lower casing, and struts disposed between the upper casing and the lower casing; and an impeller that is provided in the casing, the impeller having an annular shroud, a plurality of blades, and a main plate, wherein the main plate of the impeller has an inclined surface between an inner circumference side and an outer circumference side of the impeller, and wherein the inner circumference side of the impeller is located at an upward position in an axial direction of the impeller, and the outer circumference side of the impeller is located at an downward position in the axial direction of the impeller.

Centrifugal fan having impeller with blades between annular shroud and main plate

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Fukuroi, Japan

Tetsuya Seki