Dual‐mode power drive for active magnetic bearings

Abstract

A compact-design hybrid power amplifier for Active Magnetic Bearing (AMB) units, named as Dual Cooperative Drive Circuit (DC2), is designed and verified by intensive experiments. DC2 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 DC2 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 DC2. (iii) DC2 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 DC2 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.