发明名称 |
Circuit and method for detecting deceleration rates of a polyphase DC motor |
摘要 |
A circuit for operating a polyphase dc motor includes first circuitry for determining when the back emf of the floating driving coils crosses zero. A first counter counts a time period between a first set of zero crossings, and a second counter is loaded with the count reached by the first counter. The second counter counts a time period between a subsequently occurring set of zero crossings. If the second counter reaches zero before the occurrence of a third zero crossing, a warning signal is generated. A method for determining if a deceleration rate of a polyphase dc motor exceeds a predetermined threshold includes measuring a first period between a first set of zero crossings of the back emf of the floating driving coils, and comparing the measurement of the first period with a subsequent period between a subsequent set of zero crossings. If the subsequent period is larger than the first period by a predetermined amount a warning signal is produced. The first period is measured by counting up from zero at a first predetermined rate from a first zero crossing until a second zero crossing occurs. The comparison of the measurement of the first period with a subsequent period is done by counting down at a second predetermined rate from the count reached in the up count when the second zero crossing occurred. And the warning signal is produced if the down count reaches a zero before a third zero crossing occurs.
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申请公布号 |
US5294877(A) |
申请公布日期 |
1994.03.15 |
申请号 |
US19920876871 |
申请日期 |
1992.04.30 |
申请人 |
SGS-THOMSON MICROELECTRONICS, INC. |
发明人 |
CAMERON, SCOTT W. |
分类号 |
H02P6/12;H02P6/18;(IPC1-7):H02P5/28 |
主分类号 |
H02P6/12 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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