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电源电路中电解电容的选型应该注意哪些事项呢?
时间:2021-10-18 13:32:06   浏览次数:
  电解电容在电路设计中是必不可少的电子元器件之一,那么充分利用电解电容的优势,使其发挥最大的效果,是每个工程师追求的目标。那么,电源电路中电解电容的选型应该注意哪些事项呢?
  Electrolytic capacitor is one of the essential electronic components in circuit design, so it is the goal of every engineer to make full use of the advantages of electrolytic capacitor and make it give full play to its maximum effect. So, what should be paid attention to in the selection of electrolytic capacitor in power supply circuit?
三莹电解电容
  首先,让我们先来认知一下铝电解电容的优缺点:
  First, let's understand the advantages and disadvantages of aluminum electrolytic capacitors:
  优点:具有易获得大容量高耐压、价格低廉等显著优点,常用在电源的输入输出滤波电路。
  Advantages: it has the obvious advantages of easy access to large capacity, high withstand voltage and low price. It is commonly used in the input and output filter circuit of power supply.
  缺点:怕高温。因为铝电解电容的电解质为液态,芯子发热或环境温度较高将导致电解液挥发,长期高温导致电解液干涸失效。
  Disadvantages: fear of high temperature. Because the electrolyte of aluminum electrolytic capacitor is liquid, core heating or high ambient temperature will lead to electrolyte volatilization, and long-term high temperature will lead to electrolyte drying up and failure.
  当我们熟知电解电容的特点之后,就要根据电源电路中的应用要求,选择适合的铝电解电容器:
  When we are familiar with the characteristics of electrolytic capacitors, we should select suitable aluminum electrolytic capacitors according to the application requirements in power supply circuits:
  1、防止卤素腐蚀
  1. Prevent halogen corrosion
  铝电解电容对氯元素、溴元素等非常敏感,如果使用含卤素的助焊剂、清洗剂、固定剂、熏蒸剂,卤化物可能透过封口胶塞侵入电容器内部,极易引起电容阳极腐蚀,在上电后加速电容失效。因此必须严格管控生产工艺过程中使用的相关敏感制剂的卤素成分。
  Aluminum electrolytic capacitor is very sensitive to chlorine and bromine. If halogen containing flux, cleaning agent, fixing agent and fumigant are used, halide may invade into the capacitor through the sealing rubber plug, which is very easy to cause capacitor anode corrosion and accelerate capacitor failure after power on. Therefore, the halogen components of relevant sensitive preparations used in the production process must be strictly controlled.
  2、存储环境的控制和定期激活
  2. Control and periodic activation of storage environment
  需控制电解电容的存放环境和时间,定期进行上电赋能。
  It is necessary to control the storage environment and time of electrolytic capacitor and power on regularly.
  铝电解经长时间在高温环境下存放后,电容阳极氧化膜和电解液会发生化学反应,造成耐压下降、漏电流增大。当突然上电,电容电压接近额定电压后,可能引起过压失效或漏电流过大导致过热失效。
  After aluminum electrolysis is stored at high temperature for a long time, the capacitor anodic oxide film and electrolyte will have a chemical reaction, resulting in the decrease of withstand voltage and the increase of leakage current. When the capacitor voltage is close to the rated voltage when suddenly powered on, it may cause overvoltage failure or large leakage flow, resulting in overheating failure.
  对应单体电容特别是高压类电容,长期存放后需激活处理,建议串接1kΩ保护电阻,逐渐加压到额定电压,维持1小时左右,使得电容阳极氧化膜得以修复,漏电流回到正常水平。
  The corresponding monomer capacitor, especially the high-voltage capacitor, needs to be activated after long-term storage. It is recommended to connect 1K Ω protective resistance in series, gradually pressurize it to the rated voltage and maintain it for about 1 hour, so that the anodic oxide film of the capacitor can be repaired and the leakage current returns to the normal level.
  3、合理布局PCB上的器件,使铝电解电容远离热源。
  3. Reasonably arrange the devices on the PCB to keep the aluminum electrolytic capacitor away from the heat source.
  4、根据产品特性,选取固态电容。
  4. Select solid-state capacitor according to product characteristics.
  如:在低压大电流输出的应用场合,使用铝固态电容。铝固态电容具有极低的ESR和高纹波电流承受能力,非常适用于低压大电流的整流滤波场合。
  For example, aluminum solid-state capacitors are used in applications with low voltage and high current output. Aluminum solid-state capacitor has very low ESR and high ripple current bearing capacity, which is very suitable for low-voltage and high current rectification and filtering occasions.
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