Kas ir pieci galvenie avoti of the output ripple of the regulated power supply?
Ar the 20M osciloskops joslas platums as limit standarts, the spriegums is set to PK-PK (efektīvā vērtība is arī izmērīts), and the clip and ground wire on the oscilloscope control head are removed (jo the clip and the ground wire will form a loop, like an antenna reception Noise, introduce some unneed noise), use a zemējums gredzens (it is also possible not to use a zemējums gredzens, but the error ģenerēts by it vajadzētu jābūt ņemts vērā), connect a 10UF elektrolītiskais kondensators un a 0.1UF keramika kondensators in paralēli on zonde, and use an osciloskops The probe of osciloskops vajadzētu be testēt tieši; if the osciloskops zonde is not tieši in kontakts ar the output point, twisted pair or 50Ω coaxial cable should be use use measurement.
The output ripple of switching power supply feedly mainly comes from five aspects: input low-frequency ripple; high-frequency ripple; common-mode ripple noise caused by parazitic parameters; ultra-high-frekvence rezonanse troksnis ģenerēts laikā switching of power devices; ripple troksnis.
Ripple is an AC interference signal superimposed on a DC signal, and is a very important criterion in power supply testing. Specially for power supplies for special purposes, such as laser power supplies, ripple is one of its fatal points. Tāpēc, the test of power ripple is extremely important.
Mērīšana metode of power supply ripple is rough dalīt divos tipos: one is the spriegums signāls mērīšana metode; the other is the current signal measurement method.
Parasti, the spriegums signāls mērīšana metode var izmantot for konstante spriegums avoti or konstante strāva avoti tas do not prasa daudz ripple veiktspēja. For a konstante strāva avots ar augstas prasības for ripple performance, it is best to use the current signal measurement method.
Spriegums signāls mērījums pulsācija attiecas uz mērīšanu the AC ripple spriegums signāls virsējais ieslēgts ieslēgts līdzstrāva līdzstrāva spriegums signāls ar an osciloskops. For a konstante spriegums avots, the tests var tieši lietošana a spriegums zonde to mērīt the spriegums signāls izeja to slodze. For the test of the constant current source, the voltage waveform at both ends of the sampling rezistors is parasti mērīts ar izmantojot a spriegumu zondi. Visā tests process, iestatījums of osciloskops is the key to whether the real signal can be sampled.
Tā sekojošie iestatījumi are obligāts pirms mērījums.
1. Kanāls iestatījumi:
Joslas platums ierobežojums: izslēgts
Probe: First choose the voltage probe method. Then select the attenuation ratio of the probe. It must be consound with the attenuation ratio of the probe fact used, so that the number read from the oscilloscope is the real data. For example, if the voltage probe used is set to ×10, then at this time, the option of the probe here must also be set to ×10.
2. Trigeris iestatījumi:
Source: the channel actually selected, for example, CH1 channel is going to be used for testing, then CH1 should be selected here.
Slope: uz augšu.
Trigger mode: If you are observing the ripple signal in real time, select 'Auto' to trigger. The oscilloscope will automatically follow the changes of the actual measured signal and display it. At this time, you can also display the measured value you need in real time by setting the measurement button. However, if you want to capture the signal waveform during a certain measurement, you need to set the trigger mode to 'normal' trigger. At this point, it is also necessary to set the size of the trigger level. Generally when you know the peak value of the signal you are measuring, set the trigger level to 1/3 of the peak value of the signal you are measuring. If not known, the trigger level can be set slightly lower.
3. Sampling length (second/grid):
The setting of the sampling length determines whether the required data can be sampled. When the set sampling length is too large, the high-frequency components in the actual signal will be missed; when the set sampling length is too small, only part of the measured actual signal can be seen, and the real actual signal cannot be obtained. Therefore, in the actual measurement, it is necessary to rotate the button back and forth and observe carefully until the displayed waveform is a real and complete waveform.
4. Sampling method:
It can be set according to actual needs. For example, if it is required to measure the P-P value of the ripple, it is best to choose the peak measurement method. The number of sampling times can also be set according to actual needs, which is related to the sampling frequency and sampling length.
5. Measurement:
By select the peak measurement of the corresponsive channel, the oscilloscope can help you display the required data in time. At the same time, you can also select the frequency, maximum value, root mean square value, etc. of the corspecificing channel.
Caur saprātīgs iestatījums un standartizēta darbība of the osciloskops, the required ripple signal can be acquire. Tomēr, laikā mērījums process, care must be take to prevent other signals from interfering with oscilloscope probe pats, lest the measured signal is not true enough.
