| The digital power amplifier in Active Magnetic Bearing system is researched. The functions of PI regulating and generation of PWM wave are achieved by DSP and FPGA. A DSP and FPGA-based three-level PWM-type digital power amplifier, which use TI's DSP controller TMS320F28335 as the core processor, has been developed including hardware circuit, digital PI regulator, generation of PWM wave, and phase-shifting program of PWM wave in FPGA.Also a radiator for IGBT based on technique of heat pipe has been developed and applied in the cooling system of the power amplifier.The performance of the digital power amplifier has been tested. The experiment of static suspension and rotation of rotor on the five-degree freedom Active Magnetic Bearing system using this digital power amplifier has been carried out. In suspension experiment, the displacement of rotor in each degree of freedom is less than 10μm. When the rotor is rated at the speed of 4800r/min, the radial displacement of rotor is less than 20μm and the axial displacement of rotor is less than 10μm.The volune of the heat pipe radiator is equal to 46.7% of the aluminum radiator's. The heat pipe radiator installed in the Active Magnetic Bearing system can reduce the temperature of IGBT by 2℃after 120 minutes of stably suspending.The results show that the approach of digital design can optimize the performance of the power amplifier, such as small size and strong portability. The heat pipe radiator has the advantages of good cooling effect, saving space, reducing weight and environmental.
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