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| Light weight machine with rotor employing permanent magnets and consequence poles |
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| Support for a cooling fan |
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| Acoustic isolator for a disc drive assembly |
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| Encoder with a housing, which can be assembled |
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| Direct drive motor system |
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Brushless motor control device and equipment using the control device
| Details |
Inventors: Kawabata, Yukio; Notohara, Yasuo; Tahara, Kazuo; Takakura, Yuhachi; Ishii, Makoto; Shinozaki, Hiroshi;
Assignee: Hitachi, Ltd. (Tokyo, JP)
Primary Examiner: Dang; Khanh
Assistant Examiner:
Attorney, Agent or Firm: Antonelli, Terry, Stout & Kraus, LLP
The present invention supplies a position detection circuit, and a motor controller, that can not only obtain rotor position detection signals properly over the entire PWM control region, but also obtain these signals properly during PAM control. In a brushless motor controller based on the present invention to detect the magnetic pole position of the stator in the motor in accordance with the stator coil terminal voltages of multiple phases and control the energization of the stator coils, the comparison result information signal, after being obtained through comparison between the detected voltage values corresponding to the foregoing terminal voltages, and a reference voltage value, is directly entered into control circuits, then the position of the rotor in the motor is properly detected immediately after power-on switching, without a rotor position detection inhibition time interval being provided, and the motor is controlled properly. |
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DETAILED DESCRIPTION A feature of the present invention for achieving the objects described above is characterized in the fact that a first information signal pattern is stored into an information signal pattern storage means; and, when the first information signal pattern and a third information signal pattern are the same and a second information signal pattern is different from the other two patterns, a reflux current decay signal is generated by an information signal pattern comparison means.
According to this feature, when the first information signal pattern and the third information signal pattern are the same and the second information signal pattern is different from the other two patterns, since a reflux current is generated immediately after commutation and is then decayed, the information signal pattern comparison means compares the first information signal pattern, the second information signal pattern, and the third information signal pattern, and generates a reflux current decay signal.
Thus, the loss of the reflux current can be detected.
As a result, the position of the rotor can be properly detected immediately after commutation, without providing a rotor position detection inhibition interval, by detecting the loss of the reflux current and then detecting the rotating position of the rotor in accordance with the information signal patterns created by the corresponding information signal generation means.
Even if the load changes abruptly, the corresponding brushless motor can also be driven with rapid response, since no inhibition time interval needs to be calculated.
In addition, since rotor position detection is possible without the chopping pattern of any switching device, the position of the rotor can be detected properly, even if the upper or lower three of six switching devices low operating speed devices and are inexpensive.
Another feature of the present invention resides in the fact that the first information signal pattern that has been stored into the above-mentioned information signal pattern storage means is changed to the second information signal pattern by an information signal pattern changing means using a reflux signal decay signal
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Generators or Motors 
