Abstract: Because the Power amplifier is an actuator in the active magnetic bearing(AMB) system, it will affect the system performance directly. In order to improve AMB system performance, it must meet the indices of current response velocity, force response velocity, the maximum synchronous frequency vibration magnitude permitted and the value of unbalance control. As an example of an AMB system with minimal pulse width switch power amplifier, from the point of frequency domain, some key parameters of amplifier are designed after the analysis of actual working requirement. Through designing some main coefficients of the power amplifier reasonably, it not only keeps the system performance, but also reduces the manufacture cost. After some theory analysis and simulation, it gives some examples with the above methods. So some valuable ideas how to design an amplifier of actual AMB’s system are presented.

Key words: Active magnetic bearing(AMB), Derivative of the current, Minimal pulse width switch power amplifier(MPW), Unbalance residual