Seiko Epson Corporation

Shikoku Research Institute Incorporated

Cosmo System Corporation

Norio Ito

Hiroshi Miyazawa

Kinya Matsuzawa

Tatsuya Shimoda

Koichi Saito

Yasushi Soya

Makoto Okeya

Yasufumi Akagi

Yasunori Ueki

Hiroshi Imaizumi

Junichiro Shinozaki

Fumihiko Ishikawa

Toshiyuki Ishibashi

Hiromasa Higasa

Sumitaka Wako

Mitsuho Matsuzawa

Brushless DC motor

A brushless DC motor, whose stator (10) is a combination of stator yokes (11, 16), a bobbin (14) on which a magnetic field coil (15) is wound and to which terminal pins are provided, and a base plate (20). The stator (10) is fixed to the base plate (20) by a protrusion (12c) provided on the bobbin (14) or by a flange (18a) formed on a bearing. The widths of magnetic poles (11a, 16a) of the stator, which are measured in the circumferential direction of the stator, are smaller than the width of one of the poles of a rotor magnet (5). Thereby, the position of a stable point is a maximum excitation torque position. Further, a magnetic pole sensing element (21) is provided at a place which is shifted in the circumferential direction from the middle position of one of the magnetic poles of the rotor magnet (5).

In a radial gap type brushless DC motor having a motor structure for generating a starting torque and lowering rotational speed fluctuation by forming either one of a pair of upper and lower (right and left) claw poles to have a smaller interval in the circumferential direction with respect to the other claw pole, shifting the position of the upper or lower claw poles toward the rotating direction of the rotor from the middle position of the other claw pole and claw pole, and setting a ratio (a/p) of the claw pole width a and the pole pitch p, a ratio (b/a) of the claw pole width a and the claw pole width b, and a ratio (c/d) of the claw pole pitch c and the claw pole pitch d to fall in a prescribed range, a method for driving a motor forms the generated torque cycle of a cogging torque generated between a permanent magnet rotor (2) and a stator into large and small torque waves, and switches the current of a coil (12) at a high peak of absolute quantity or in the vicinity thereof among a plurality of positive peaks of the cogging torque. Further, a method for driving a motor wherein the coil current is switched at a position where the excited torque generated by the coil current becomes zero or in its vicinity. And, a method for driving a motor wherein the coil current is switched in a vicinity of a positive peak of the cogging torque and giving a no-current passing period when switching the coil current.

Brushless DC motor and method for driving the same

A superconducting bearing device comprising a superconductor mounted on a stationary member and a magnet section to be mounted on a rotating member, the superconductor and the magnet section being disposed to oppose each other with a gap therebetween. Also disclosed is a method for producing the magnet section thereof, wherein the magnet section consists of a plurality of annular permanent magnets which are concentric with the axis of the rotating member and also include at least one soft magnetic yoke disposed between these annular permanent magnets. Each annular magnet, in turn, may be comprised of a plurality of arcuate magnet portions whose joint surfaces may be concentrically or axially staggered to disperse nonuniform flux densities observed at their junction surfaces. The joint surfaces between the annular and magnets and the interposing rings may be curved or slanted to reduce axial displacement when the magnet section is rotated. Also, the yoke members may protrude towards the superconductor relative to the permanent magnets comprising the magnet section, and these yokes may be optimally shaped to concentrate and direct magnetic flux to the opposing superconductor in conjunction with curled magnetization of the permanent magnets. Finally, one or more restraining members or wedge portions may be fitted to the magnet section to radially and circumferentially compress the permanent magnets sections and prevent their displacement and breakage at high rotational speeds.

Superconducting bearing device

Horizontal and vertical displacement detector of wire rope

Displacement sensor with temperature compensation by combining outputs

Superconducting bearing

A power converter/inverter system for a load comprises a converter circuit for converting an alternating current power input into a direct current power intermediate signal in response to a first PWM voltage. An inverter inverts the DC power intermediate signal into an AC power output in response to a second PWM voltage. A smoothing filter is arranged in series between a converter and the inverter for filtering the DC power intermediate signal. An instantaneous real power calculating circuit calculates an instantaneous real power (IRP) relative to the inverter and is determined by a torque current command value and a load angular speed signal. A converter controller controls the first PWM voltage of the converter in accordance of a combination a predetermined converter amplitude setpoint, a DC voltage present at the DC power intermediate signal, and the instantaneous real power product. An inverter controller controls the second PWM voltage of the inverter in accordance with the inverter amplitude setpoint and amplitude of the AC power output.

Power converter/inverter system with instantaneous real power feedback

A voltage PWM converter/inverter system comprises a converter for converting an alternating current power input into a direct current power output and inverting the direct current power output of the converter into an alternating current power output. A smoothing circuit is inserted between the converter and the inverter and an instantaneous real power calculating unit calculates an instantaneous real power for the inverter to provide an output comprising an instantaneous real power calculated value. The system includes a converter controller for voltage PWM control of the converter based on a set converter command value, a terminal direct current voltage value of the smoothing capacitor, and the instantaneous real power calculated value. The system further includes an inverter controller for voltage PWM control of the inverter based upon a set inverter command value and the alternating current power provided as a an output by the inverter.

Power conversion system with instantaneous real power feedback control

A back-light device increases the level of luminance produced by a fluorescent lamp at low and high ambient temperatures by increasing the ballast capacitance at these temperatures. The ballast capacitor can include one or more capacitors made from ceramic or the like. The back-light device can be used with different types of video display apparatuses which employ a transmission-type video display plate.

Back-light device for a video display apparatus

Growing community of inventors

Suwa, Japan

Norio Ito