本文为数字交流电桥提供了大范围快速平衡的理论。论证表明，通过对电桥的可调参数任意调节两次，由两次调节所形成的误差电压的傅里叶系数即可完全确定电桥平衡的参数，得到被测阻抗Ｚｘ的值。该理论非常便于数字化方法实现，并为快速平衡数字交流电桥的实施方法提供了指导性的理论依据 This article provides a theory of large-scale fast balancing for digital AC bridges. The demonstration shows that by adjusting the adjustable parameters of the bridge twice, the Fourier coefficient of the error voltage formed by the two adjustments can completely determine the parameters of the bridge balance and obtain the value of the measured impedance Zx. The theory is very easy to implement digital methods and provides a theoretical basis for quickly balancing digital AC bridge implementation methods