| 摘要 |
PURPOSE:To prevent position or speed from depending on gap variation, by negating the ripple component generated by gap variation from the voltages, which are induced by four sets of coils of a detection part, by operation. CONSTITUTION:The voltages V1-V4 induced in four sets of detection coils 1-4 are transmitted to a signal processing part 20 and detection voltage V0 is obtained by an adder 5. This voltage V0 contains a ripple component due to gap variation. In order to remove this ripple component, the polarities of the voltages V2, V4 are reversed by inverters 10, 11 and a signal VA is obtained along with the voltages V1, V2 using an adder 6. Next, the average value of the voltages V1-V4 is obtained using absolute value circuits 141-144 and LPF 151-154 and signals VM, VD are obtained using inverters 12, 13 and adders 7, 8. Further, a compensation signal VC is obtained using the signals VA, VM, VD, a divider 16 and multipliers 17, 19. Subsequently, the signals VC, V0 are added by an adder 9 to obtain a compensated detected signal VthetaC. This signal VthetaC is processed by a position and speed detection circuit 18 to make it possible to detect a position and a speed generating no ripple.
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