一种基于DSP的商用多通道多频同步RLC数字电桥,由一组自平衡电桥、激励信号发生器、同步采样电路及同步处理电路构成；这种电桥采用DDFS产生多谐激励信号激励,采用多频激励,通过四端口方式测量电抗并行测量电感器件在50Hz～100kHz内多频点的参数；文中介绍通过选择合适的累加器位数与LUT的长度,设计无相尾截尾的多谐激励信号发生器；文中还讨论影响测量精度的因素,分析了算法的计算复杂性、精度,并对其测量精度进行了仿真分析,取得令人满意的结果,单次测量的相对误差高子0.1％,2000次测量结果的平均精度可达0.05％.%A commercial multi-channel RLC bridge measuring system has been developed for the on-line measurement of inductor in multi-frequency point with commercially available DSP, high -resolution ADC and DAC. It consists of a group of self-balancing bridge circuits, exciting signal generator, quasi synchronous sampling system and processing system. With this bridge measuring instrument, inductors can be estimated simultaneously by measuring their impedances in the four-terminal-pair, excited by a multi-frequency signal in parallel at frequencies over the range from 50 Hz to 100 kHz. The direct digital signal synthesizer without phase truncation is designed by selecting an appropriate size of look up table and a word length of phase accumulator. The precision and the factors affect on it is discussed, and the computation complexity is also analyzed. Simulations are made to show satisfactory performance, the relative error of one measurement is above 0. 1% , and the mean precision of 2000 measurements can reach 0. 05%.
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