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Anonymous users2024-02-06For switching ripple, it must exist both theoretically and practically. There are five practices that usually suppress or reduce it:
1. Increase the inductance and output capacitance filtering.
According to the formula of switching power supply, the current fluctuation in the inductor is inversely proportional to the inductance value, and the output ripple is inversely proportional to the output capacitance value. Therefore, increasing the inductance and output capacitance can reduce ripple.
2. The second-stage filter is to add another first-stage LC filter.
The LC filter has an obvious effect on the suppression of noise ripple, and the appropriate inductor capacitor is selected to form a filter circuit according to the ripple frequency to be removed, which can generally reduce the ripple well.
3. After the switching power supply output, connect the LDO filter.
This is the most effective way to reduce ripple and noise, the output voltage is constant and does not require changes to the original feedback system, but it is also the most expensive and power consuming method.
4. Capacitor C or RC on the diode
When the diode is turned off at high speed, the parasitic parameters should be considered. During diode reverse recovery, the equivalent inductance and equivalent capacitance become an RC oscillator, producing high-frequency oscillations. In order to suppress such high-frequency oscillations, a capacitor C or RC buffer network is connected in parallel at both ends of the diode.
The resistance is generally 10 -100, and the capacitance is taken.
The value of capacitor C or RC connected in parallel on a diode can only be determined after trial and error. If it is not selected correctly, it will cause more severe oscillations.
If high-frequency noise is critical, soft switching technology can be used. There are many books dedicated to soft switching.
5. The diode is followed by an inductor (EMI filtering).
This is also a commonly used method of suppressing high-frequency noise. Selecting the appropriate inductive element for the frequency at which the noise is generated can also be used to suppress the noise. It should be noted that the rated current of the inductor should meet the actual requirements.
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Anonymous users2024-02-05It is recommended to add an LC filtering network or a PFC circuit.
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Anonymous users2024-02-04Ripple current is defined as the higher-order harmonic component of an electric current. This will bring about a change in the amplitude of the current or voltage, which may lead to breakdown, and because it is an AC component, it will be dissipated on the capacitor, and if the ripple component of the current is too large and exceeds the maximum allowable ripple current of the capacitor, the capacitor will burn out.
In switching power supplies, there will always be capacitance due to voltage conversion and holding.
Then, assuming that the output has a large ripple current, if the current capacity of the device is exceeded by the rated current capacity of the device, the device will be damaged.
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Anonymous users2024-02-03Ripple. The main harms are 1. It is easy to be in.
with electrical appliances. on.
Surge voltage. Or.
Current. resulting in the burning of electrical appliances; 4. It will interfere.
Digital circuits. logical relationship that affects its normal functioning. That's about it. If you want to suppress it, there will be more content, you can check the relevant information, and the ripple is divided into different types, such as: input low-frequency ripple, high-frequency ripple, parasitism.
Parameter. caused.
Common mode. Ripple. Noise.
Power. Devices.
Switch. process.
UHF. Resonant.
Ripple noise caused by noise and closed-loop regulation control. Different ripple suppression methods are also different. In the case of low-frequency ripple, it can be filtered by increasing the output of low-frequency filtering.
Inductance, capacitance.
parameters to achieve the purpose of suppression.
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Anonymous users2024-02-02Using inductance, capacitance and resistance at the same time will have a more obvious effect.
An inductor is connected in series in the load loop of the rectifier circuit to make the output current waveform smoother. Because the impedance of the inductor to DC is small, and the impedance of AC is large, it can get a better filtering effect and less DC loss.
A capacitor is connected in parallel in the rectifier circuit, and when the input voltage rises, the capacitor is charged, and part of the energy can be stored in the capacitor. When the input voltage decreases, the voltage at both ends of the capacitor is discharged exponentially, and the stored energy can be released. The filter circuit discharges to the load, and the output voltage obtained from the load is relatively smooth, which plays a flat wave role.
Connecting a resistor in parallel in the rectifier circuit and landing the residual ripple voltage on both ends of the resistor can significantly improve the filtering effect.
As for the size of the problem, this is determined by the power size, output voltage requirements, temperature qualitative, volume limit, matching, etc., it is meaningless to not match it, some can not exceed the matching, some over-matching is meaningless, the inductance and resistance are large or small, will change the output voltage, the capacitance exceeds the matching is meaningless, etc.
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Anonymous users2024-02-01The easiest way to do is to replace the output filter capacitor with a solid state and connect a high-quality CBB in parallel.
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Anonymous users2024-01-31The stability of a switching power supply may be the same as that of a linear power supply, but ripple and noise affect the stability of a switching power supply, and in order to improve its stability, it is necessary to take measures to eliminate these effects. However, its stability will not be problematic for general usage.
There are many components in switching power supplies, so the reliability is lower than that of linear power supplies. However, for switching power supplies that are commonly designed, the lifetime of the electrolytic capacitor greatly affects its reliability, and the higher the temperature, the shorter the lifetime of the electrolytic capacitor. Therefore, for the same size of switching power supply, the high efficiency of the switching power supply has a lower temperature rise, which can improve the reliability.
However, since the components of the switching power supply are too small and the temperature rise is high to balance the internal losses, it is possible to create a switching regulated power supply with low reliability, so it is necessary to pay attention to this. In particular, recently, not only the performance of switching components has improved, but the switching frequency has also become more frequent, making it easier to miniaturize switching power supplies. However, it is more difficult to reduce losses than to miniaturize, so it is important to select components that do not degrade in reliability at high temperatures while designing for optimal heat dissipation.
Electrolytic capacitors, which have a very short life as fixed components for switching power supplies, have recently had their life extended; Due to the increasing frequency, the capacitance of filter capacitors may also be reduced, so multilayer ceramic capacitors can be used. In this way, it is possible to produce a highly reliable switching regulated power supply without electrolytic capacitors.
If you want to avoid impetuousness, you must first be aware of this problem, and now that you have recognized the harm of impetuousness, it means that you have actually begun to detach yourself from the impetuous state of mind. I think to avoid impetuousness, the most important point is to be content, only people who are dissatisfied with the current situation will have impetuousness, dissatisfied with the economic situation will keep jumping ship, dissatisfied with love will keep breaking up, and so on, when you have a solid and contented sex, of course, you can't become no pursuit, but the key is that this pursuit is unrealistic, if it is not realistic then forget it as soon as possible, if it is realistic, you must make solid efforts to achieve it, but also remember, Putting in the effort doesn't necessarily mean the results, it's the process that matters. In a word, people will not be impetuous if they are not greedy, go through their lives steadily, don't always envy those who are more successful than themselves, don't pick up sesame seeds and lose watermelons.
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