Measurement method of frequency and phase of AC signal
A technology of AC signal and measurement method, applied in the direction of frequency measurement device, phase angle between voltage and current, frequency to phase shift conversion, etc., can solve problems such as signal interference or inaccurate frequency, inaccurate phase measurement, etc., to achieve Improve measurement accuracy, accurate frequency, and good anti-interference performance
Active Publication Date: 2017-11-24
NINGBO UNIV
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Problems solved by technology
These two methods can accurately obtain the phase of the AC signal, but the first method needs the help of a timer, and the second method needs the help of an AD converter; in addition, the two methods will be due to signal interference or inaccurate frequency, lead to inaccurate phase measurements
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[0018] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.
[0019] A method for measuring the frequency and phase of an AC signal proposed by the present invention, its realization flow diagram is as follows figure 1 As shown, it includes the following steps:
[0020] ①Order F 1 Indicates the frequency measured when the AC signal crosses the first zero point, and let F 1 =F; let P 1 Indicates the phase determined when the AC signal crosses the first zero point, and let P 1 = 0 degrees; where, F represents the estimated frequency of the AC signal, and the unit is HZ, and the value of F is estimated according to the application occasion of the AC signal. If the AC signal is applied to the power grid, F=50HZ or F=60HZ can be set.
[0021] ② Assuming that the current AC signal passes the i-th zero point, read the time when the AC signal passes the i-th zero point, which is recorded as t i , the unit i...
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The invention discloses a method for measuring the frequency and phase of an AC signal. Firstly, the measured frequency and the determined phase are given when the AC signal passes through the first zero point; then the time when the AC signal passes through the current zero point is read; and then Determine whether the current zero point is an interference signal by judging whether the frequency in the time period between the current zero point and the previous zero point of the AC signal is within a reasonable range; when the current zero point is a non-interference signal, then according to the current reading Calculate the frequency when the AC signal passes the current zero point, and determine the AC signal crossing the current zero point according to the current read time and the frequency measured when the AC signal passes the previous zero point The phase at time; the frequency and phase when the AC signal crosses each zero point can be repeatedly obtained in real time; the advantage is that even in the case of large grid interference or waveform distortion, the frequency can still be accurately measured, and the phase can be accurately determined, and the anti-interference performance it is good.
Description
technical field [0001] The invention relates to an AC signal detection technology, in particular to a measurement method for the frequency and phase of the AC signal. Background technique [0002] In many control systems, it is often necessary to detect grid or other AC signals, and when detecting AC signals, it is necessary to measure the zero point of the AC signal and the frequency and phase of the AC signal. [0003] At present, the methods for measuring the frequency of AC signals include the timing method of measuring the cycle and the counting method of measuring the number of signals at regular intervals. Generally, the fixed frequency of AC signal is 50HZ or 60HZ, but in actual use, the frequency is not necessarily strictly 50HZ or 60HZ, and there is a certain deviation. At the same time, due to the common use of electronic equipment, the waveform of the power grid will be deformed or seriously interfered. In this case, the measurement result of the above method fo...
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IPC IPC(8): G01R23/12G01R25/00
Inventor 俞建定王青文化锋
Owner NINGBO UNIV