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The definition and characteristics of the DC stable power supply ripple

Issuing time:2015-07-16

Since the DC stable power supply is generally rectified voltage from the AC power supply and other aspects of the formation, which inevitably DC stabilizing amount of how many exchanges with some ingredients, such superimposed on the AC component of the DC stabilizing amount would call it a ripple. The ripple component is more complex, its shape is generally similar to the sine wave frequency is higher than the harmonic frequency, the other is very narrow pulse width. For different occasions, each ripple requirements are not the same. For capacitor sophisticated, no matter what kind of ripple, as long as not too much, generally will not affect the quality of capacitor seasoned. The program control unit for the power supply or audio equipment used, due to the very narrow pulse width not have enough energy to drive the speaker cone or a telephone handset to form noise. Therefore, the requirements for such a narrow pulse can be relaxed.

   For similar ripple sinusoidal signals in the audio range, although its rate is not too high, but their energy while filling the speaker or the handset occurs buzzing noise. Therefore this form should be a ripple requirements, while for some control of the case, since the narrow pulse reaches a certain height would interfere with digital or logic control unit, reducing the reliability of equipment operation, and therefore this narrow pulse amplitude should be limited, while the similar sinusoidal ripple, generally because of its low magnitude, less interference on the control unit.

   Ripple representation can be represented by RMS or peak, you can use absolute amount, relative to the amount can also be used to represent. For example, a power supply operates in regulated state, its output is 100V5A, the measured effective value of the ripple 10mV, the absolute amount of which is the ripple of 10mV, but that is the relative amount of ripple factor = ripple voltage / output voltage = 10mv / 100V = 0.01%, which is equal to one.

   Ripple is a DC voltage of the AC component. DC voltage was supposed to be a fixed value, but many times it is through the AC voltage rectifier, filtering can be accomplished, because the filter is not clean, there will be a surplus of the AC component, even so, is to use battery power but also because of the load fluctuations of the ripples. In fact, even the best voltage reference device, the output voltage is corrugated.

     General use AC ripple voltage meter to measure mV, AC mV table only because AC voltage response, and relatively high sensitivity, small measure AC voltage, and is often relatively small ripple AC voltage. If there is no AC millivoltmeter can also be measured using an oscilloscope. The oscilloscope's input is set to AC coupling, adjust Y-axis gain, the waveform right size, read voltage value can be estimated magnitude of the ripple voltage. The ripple voltage will affect the operation of the system, bring the noise. Therefore, there must be enough power supply filtering measures to limit the ripple within a certain range.

Comparison of harmonics and ripple

   Harmonic simply put, is the role of a certain frequency voltage or current in non-linear load, it will produce different from the original frequency of other frequency sinusoidal voltage or current phenomenon. Refers to the ripple DC voltage or current, the AC component is superimposed on the DC stabilizing amount. Although they are not the same thing in concept, but there is a link between them. Such as additional power supply ripple in the appliance is easy to produce with each frequency harmonics; there is a power in each frequency harmonics undoubtedly lead to an increase in the ripple component of the power supply. In addition to the case in the circuit we need to generate harmonics, which are mainly the following major hazards:

1, so that the power grid caused by resonance over-current or over-voltage caused by the accident;

2, add an additional loss, reducing efficiency and equipment utilization for power generation, transmission and electrical equipment;

3, so that the electrical equipment (such as rotary motors, capacitors, transformers, etc.) is not functioning properly, accelerated insulation aging, thus shortening their life;

4, so that relay protection, automatic devices, computer systems and a lot of electrical equipment is not functioning properly, or does not operate normally or operation;

5, the measurement and measurement instruments, meters can not correctly indicate or measure;

6, interfere with communications systems to reduce the transmission quality of the signal, disrupting the normal signals are transmitted, and even damage communications equipment.

Ripple harm:

1, easy to produce harmonics on electrical appliances, and harmonics will produce more harm;

2, reducing the efficiency of the power supply;

3, strong ripple will cause the generation of surge voltage or current, resulting in burning appliances;

4, can interfere with digital logic circuits, affecting its normal work;

5, will bring noise, image equipment, audio equipment does not work properly.

   In short, they appear are harmful in a place we do not, we need to avoid. For how to suppress harmonics and ripple and removal There are many ways, but would like to be completely eliminated, it seems difficult to do, and we can only be controlled within a permissible range, and do not impact the environment and equipment even reach our aim.

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