摘要：The current mode switching power amplifier is an essential component in magnetic bearing system which works in the nonlinear switching state. At present, the characteristics of the power amplifier can be revealed partially by establishing first order inertial element model. In order to accurately investigate the actual working characteristics of the current mode power amplifier, a precise mathematical model of switching power amplifier is proposed based on the circuit principle and Fourier series analysis method. In the analysis of the current forming principle for three-level Pulse Width Modulation (PWM) power amplifier, the load coil voltage is deduced by Fourier series method. The steady state current model and ripple current model are established, respectively. Compared with the model simulation and experiment, the results show that the characteristics of the ripple current, steady state and dynamic state are basically consistent. We found that the model predictions results are in excellent agreement with the actual experiments data, indicating the numerical simulations model is feasible and effective for the design of power amplifier system.
