With the continuous improvement of industrial automation, frequency converters have been more widely used, in which capacitors are indispensable. So what specifications of capacitors should be selected to be more suitable for use in frequency converters?

　　变频器是利用电力半导体器件的通断作用将工频电源变换成另一频率的电能控制装置。变频器主要由整流（直流变交流）、制动单元、驱动单元、微处理单元等组成。在电容器中铝电解电容和薄膜电容都应用于变频器中。

　　Frequency converter is a power control device that uses the on-off function of power semiconductor devices to convert power frequency power supply into another frequency. The frequency converter is mainly composed of rectifier (DC to AC), braking unit, driving unit, micro processing unit, etc. In capacitors, aluminum electrolytic capacitors and film capacitors are used in frequency converters.

　　电容器家族当中电解电容、薄膜电容、超级电容、贴片电容、陶瓷电容等应用于不同的领域中。

　　Among the capacitor families, electrolytic capacitors, film capacitors, super capacitors, patch capacitors, ceramic capacitors, etc. are used in different fields.

　　电解电容作为整流滤波电容在变频器中起着重要作用。不过在工作过程中，铝电解电容器的损耗很大，其中无功损耗可以占到总无功容量的20%，而且会随着频率的增大而增大，损耗以热量形式散发，导致铝电解电容更容易发热，使用工作时间短，故障率更高。铝电解电容的损坏常常导致整台设备无法继续运转。

　　Electrolytic capacitor plays an important role in frequency converter as a rectifier and filter capacitor. However, in the process of operation, the loss of aluminum electrolytic capacitors is very large, among which the reactive power loss can account for 20% of the total reactive capacity, and will increase with the increase of frequency. The loss is distributed in the form of heat, which leads to aluminum electrolytic capacitors being easier to heat up, shorter working time and higher failure rate. The damage of aluminum electrolytic capacitor often causes that the whole equipment cannot continue to operate.

　　薄膜电容具有无极性、介质损耗小，寄生电感低、阻抗低、温度特性好、体积小、工作时间长等优势。在同等容量中，薄膜电容的耐纹波电流能力要高于铝电解电容器的耐纹波电流，薄膜电容器的低阻抗使开关管上的电压应力大大减小，有利于开关管工作的可靠性和稳定性。

　　Thin film capacitors have the advantages of non polarity, low dielectric loss, low parasitic inductance, low impedance, good temperature characteristics, small size, long working time, etc. In the same capacity, the ripple current resistance of the film capacitor is higher than that of the aluminum electrolytic capacitor. The low impedance of the film capacitor greatly reduces the voltage stress on the switch tube, which is conducive to the reliability and stability of the switch tube.

　　和铝电解电容相比，薄膜电容更适合变频器。在使用过程中薄膜电容能工作很长时间，在变频器中可以做到免维护，大大节约维护成本和人力，避免了变频器电器替换电容器的麻烦和成本的提高。在变频器中薄膜电容逐渐取代铝电解电容是必然选择。

　　Compared with aluminum electrolytic capacitor, thin film capacitor is more suitable for frequency converter. The film capacitor can work for a long time in the process of use, and can be maintenance free in the frequency converter, which greatly saves maintenance costs and manpower, and avoids the trouble of replacing capacitors with inverter appliances and the cost increase. It is inevitable to replace aluminum electrolytic capacitor with thin film capacitor in frequency converter.