| 摘要 |
In an electromagnetic bearing system for a shaft, the position of the shaft is measured and the current supplied to the coils of an array of electromagnets radially surrounding the shaft is controlled so as to maintain the shaft at a desired position. The coils are arranged in diametrically opposed pairs and each coil has a drive circuit including first and second switching transistors which transfer current pulses to the coils. Circulating diodes become conductive when the coils are switched off to transfer energy stored in the coils back to the power supply so as to be available for coils already, or about to be, turned on. The drive circuits for the coils interleave on and off periods for the coils so that one coil of the pair is being switched on at roughly the same time that the other is in a pair are operated so Energy from shut down coils that would otherwise need to dissipated in a shunt is thus diverted for use in an on-turning coil and power consumption is reduced. <IMAGE>
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