| 摘要 |
PROBLEM TO BE SOLVED: To perform accurate field current abnormality detection and make a circuit inexpensive in the field current control circuit of a field winding type motor. SOLUTION: Current flowing in a field coil 5 is detected to provide a second operation amplifier 6 for outputting a real current detection value corresponding to the detection value, a third operation amplifier 7 for generating a field current reference value on the basis of partial resistors R2, R3 being the same resistance value as the field coil and the partial voltage values is provided, the fluctuation of the real current detection value is discriminated by prescribed width for the field current reference value, and a window comparator 9 for detecting abnormality is provided. Since a field current abnormality detection means can be composed of a logic circuit, the circuit can be made not only inexpensive but also can detect the abnormality by considering the unevenness of the resistance value of the field coil, and a degree of freedom suitable for the circuit is increased.
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