Complementary cooperation of dual power circuits to drive active magnetic bearings

A compact-design hybrid power amplifier for AMB (active magnetic bearing) 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 analog 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 PWM (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 a high-current slew rate so that the response of AMBs is 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 compliant with digital controllers and DSPs (digital signal processors) since the commands or drive sequences are all in DC (direct current) manner.