In order to obtain the core loss under different frequencies and different magnetic flux densities, the frequency and amplitude of excitation waveform in the testing system should be arbitrarily adjusted. The paper studied the sinusoidal excitation waveform, which has a variable frequency based AD9834 and an adjustable amplitude based on AD5620. Single chip microcomputer controls the waveform by the SPI three-wire serial port. The experiment results show that the system can supply a variable frequency and an adjustable amplitude of the sinusoidal waveform, with wide frequency range and good stability, which provides reliable sinusoidal excitation in the testing system of core loss for high frequency switching converter.%为了获得磁芯在不同频率和磁通密度下的正弦激励损耗，高频磁损测试平台系统应能够可靠有效地调节激励波形频率和幅值。研究基于直接数字合成技术AD9834芯片产生所需频率的正弦信号，并通过与DAC芯片AD5620结合调制正弦信号源的幅值，单片机可通过SPI三线串口对信号源进行实时调节。实验结果表明，该系统可以得到幅值、频率连续可调的正弦波，输出频率范围宽，稳定性好，可以为高频磁芯损耗测试平台提供可靠的正弦信号源。
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