Metallized film capacitor dynamic performance

The metallized film capacitor uses a polyester film or a polypropylene film as a medium, and the zinc aluminum alloy is trapped on the surface of the film by vacuum evaporation to form an electrode by a non-inductive stepless winding or lamination to form a capacitor. Metalized thin electric passengers have high withstand voltage, high insulation resistance, good impedance frequency characteristics (smaller parasitic inductance), low ESR, high capacity characterization, and low loss tangent.

The gold film capacitor is used for signal transmission, coupling, and voltage reduction on the electric energy meter. Metallized polyester film capacitors, as coupling capacitors, have high insulation resistance and can couple AC signals or pulse signals to the subsequent stage without damaging, while not affecting the DC operating point of the latter stage. Metallized polypropylene film capacitors are used as Due to its low frequency tangent and high capacity stability, the step-down capacitor can reduce the AC high voltage to the AC low voltage that meets the requirements of the latter stage, replacing the original transformer, making the product smaller and more stable.

The dynamic performance of the film capacitor essentially means that the capacitor operates under the normal working conditions of the electronic equipment under the action of high frequency, high voltage, high pulse, large current, does not cause the mg increase of tgδ value, the temperature rise of the film capacitor itself is too high, performance Distortion, even failure, and other phenomena, and the capacitor can work stably, when the capacitor is manufactured, the performance of the capacitor is determined by static measurement parameters.

There are very few dynamic test equipment to determine the dynamic performance of the capacitor, which determines the performance of the metallized film capacitor under dynamic operating conditions can not grasp the cause of failure is also difficult to determine, such as manufacturing problems, high frequency, high pressure tg δ The increase in value leads to heat generation in long-term work, resulting in thermal breakdown. In the static test, only the high-frequency tgδ value can be used to judge the performance of the product, and the high-frequency test cannot be performed under high voltage and pulse state, which results in limitation.

The ways to improve the dynamic performance of metallized film capacitors are as follows:

The research and test were carried out using a new hot pressing process and high-voltage short-circuit discharge, using the surge current generated by high-voltage and short-stroke discharge, and then determining the performance of the capacitor at a high-frequency tgδ value, so that the process can be eliminated. Control products that are prematurely ineffective, thereby improving the dynamic performance of the product.