Dual‐mode power drive for active magnetic bearings

A compact‐design hybrid power amplifier for Active Magnetic Bearing (AMB) units, named as Dual Cooperative Drive Circuit (DC 2 ), is designed and verified by intensive experiments. DC 2 can operate under dual mode: either Digital Driving Mode (DDM) or Analogue Driving Mode (ADM). By taking advantages of the complementary cooperation between DDM and ADM, the proposed DC 2 manifests its superiorities mainly in three aspects. (i) Compared to a traditional 2‐level Pulse‐Width Modulation drive circuit, the improvement degree of reducing the amplitudes of current ripples is up to 62%. (ii) By taking advantages of mutually complementary cooperation between DDM and ADM, the steady‐state errors of output current, which is exerted to the coils of AMBs, can be much reduced by DC 2 . (iii) DC 2 can provide high current slew rate so that the response of AMBs is pretty fast and quick enough to regulate the high‐speed rotor back to the neutral position within a very short time period below 0.40 ms. In addition, the proposed DC 2 is particularly suitable to be complied with digital controllers and Digital Signal Processors since the commands or drive sequences are all in Direct Current manner.