Research On Bidirectional Digital Power Amplifier Based On FPGA

In order to further improve the integration of control system and meet the requirement of permanent magnet biased magnetic bearing for bipolar current,a bidirectional digital power amplifier based on FPGA is studied and developed.The mathematical model of bidirectional switching power amplifier are deduced by using the Fourier series theory.The expression of the system's step response is derivated and simulated to evaluate the influence of damping ratio and natural frequency,which can provide theoretical basis for the design of control parameters.The correctness of parameter design is verified by the combined simulation model of control algorithm and hardware circuit in MATLAB/Simulink.On this foundation,the hardware circuit of the digital power amplifier based on FPGA chip is designed,which can improve the integration and control precision of the power amplifier system.In software design,programming realization and simulation validation of PI control algorithm and three level PWM modulation algorithm with FPGA language is particularly introduced.Based on the experimental analysis,an improved current loop control algorithm is introduced to improve the dynamic performance.The effect of the dead zone nonlinearity is studied based on the current response and Fourier analysis,a dead-time compensation method is proposed based on theoretical analysis,which can effectively reduce the dead zone nonlinear interval.According to the results of test,the power amplifier has a good static and dynamic performance,which can be kept in a large load range.The experiments using this bidirectional digital power amplifier on permanent magnetic biased magnetic bearing test-bed have been carried out.The stable suspension of the rotor is achieved and the displacement of rotor in each degree of freedom is less than 24?m.When the rotor is rated at the speed of 3000r/min,the displacement of rotor is less than ±30?m.