| 摘要 |
PROBLEM TO BE SOLVED: To provide a short-circuit detecting circuit for an electromagnetic apparatus, which is able to prevent degradation in detection accuracy without using a capacitor for a circuit provided for short-circuit detection.SOLUTION: For a coil I2_1, a comparison voltage generation circuit 4(1) generates a comparison target voltage V1 by adding offset voltage V3 to the sum of terminal voltages using ground as reference. A comparison circuit 6(1) compares the comparison target voltage V1 with a threshold voltage VT1. For a coil I2_2, a comparison voltage generation circuit 4(2) generates a comparison target voltage V2 by adding offset voltage V4 to the sum of the terminal voltages using ground as a reference. A comparison circuit 6(2) compares the comparison target voltage V2 with a threshold voltage VT2. Threshold voltage generating circuits 7(1, 2) generate threshold voltages VT1, VT2 as a voltage signal that changes at the same frequency as an excitation signal input to an excitation coil I1. A digital filter 8 receives signals output from the comparison circuits 6(1, 2). When a short circuit between the coils I2_1 and I2_2 is detected on the basis of a change in the output signal, a short circuit detection signal is output. |
