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US 2008/0303464 A1Published application
Brushless Dc Motor and Electric Apparatus Mounting It
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorMasayuki Takada
Life of this patent
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Abstract
Current control circuit controls an output voltage of DC power supply so as to increase current passing through inverter circuit as the motor increases its the speed. The control offers an RPM—torque characteristic of the motor in which torque increases as the RPM increases. By virtue of the RPM—torque characteristic, a ventilating device employing brushless DC motor exhibits preferable air quantity—static pressure characteristic where less change in air quantity is expected even when a pressure loss-outside wind pressure, duct length or the like—varies.
Claims14
A brushless DC motor comprising:
- a stator having a stator coil;
- a permanent-magnet rotor disposed opposite to the stator;
- a rotor magnetic-field detecting element for detecting a magnetic field of the permanent-magnet rotor;
- a rectifying circuit for rectifying AC voltage of an AC power supply in full-wave;
- a DC power supply for converting the voltage rectified by the rectifying circuit into a low DC voltage;
- an inverter circuit having a plurality of switching elements in full-wave bridge connection, to which the DC voltage is applied;
- a driving logic circuit for controlling the switching elements to pass current through the stator coil;
- and
- a current control circuit for controlling current passing through the inverter circuit,
- wherein the current control circuit increases the current passing through the inverter circuit as the motor increases its speed.
7 more elements
Dependencies are inferred from the claim text.