How to ensure accurate measurement of frequency

- Jul 23, 2018 -

The phenomenon of data jitter and efficiency abnormality of the power analyzer during testing often has a great relationship with the accurate measurement of the frequency of the signal. This paper analyzes the importance of frequency measurement and hopes to help you to make more accurate. measuring.

First let's see why the measurement of frequency has such a large impact on other parameters.

Synchronization source selection

Engineers who have used the power analyzer will remember that when setting up the instrument, a setting option called “synchronization source”, which includes the voltage and current of each test channel, can be selected by the engineer. The choice of this option has little effect on the DC signal test, but it has a great impact on the AC signal test. The reason is because if the interval of the AC signal measurement data is not synchronized with the signal period, the data equivalent to the test is a non-perfect period, and the calculation result will be inaccurate. The period in which the power analyzer detects and calculates the signal is determined by the source of synchronization, so choosing an accurate source of synchronization is critical to the test results. The principle of synchronization source selection is to select the signal close to the sine wave as much as possible. For example, the grid power frequency is generally selected as the synchronization source, and as the PWM signal of the motor drive output, we can select the current as the synchronization source.

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