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　　Frequency converter has been widely used in various fields. The inverter structure is complex, involving a wide range of knowledge, the fault types of all sorts of strange things more difficulty in maintenance. In order to improve the maintenance level quickly, the maintenance personnel should not only have a certain theoretical basis, but also have to master certain practical methods.

　　The speed regulation of AC motor by frequency conversion technology is much faster than traditional DC speed regulation in performance index, and it is superior to DC motor speed regulation in many aspects. Therefore, in all fields, the frequency converter has been widely used. However, in the frequency converter, like everything else in nature, there is the problem of aging and life span. In the long run, the components in frequency converter will inevitably have such or other failures for various reasons.

　　It is not easy to repair the frequency converter quickly. It involves a wide range of knowledge and strong professionalism. In order to improve the maintenance level quickly, the maintenance personnel should not only have a certain theoretical basis, but also have a lot of practical experience. In combination with several specific maintenance cases, the author introduces several practical methods for the maintenance of frequency converters.

　　1 step down method

　　The so-called gradual reduction method is through the analysis of the fault phenomenon, the judgement of the measurement parameters, the narrowing of the fault scope, and the final implementation of the specific circuit or components produced by the fault. It is essentially a affirmative, negative, reaffirmation, and reaffirmation, and the final affirmative (judgment) judgment process.

　　For example, after a frequency converter is electrified, it is found that there is no display on the operating disk. The first judgment is certainly no DC power supply (available multimeter to measure the DC power supply voltage), further examination, found that high light is bright (PN voltage measurements further confirmed), negative fault main circuit of high voltage circuit, a power supply to the road must operation panel power supply switching power supply problem. Measuring the AC voltage of the power supply is normal, no DC output, and no short circuit phenomenon, it can be concluded that the rectifier tube is damaged. This example is a typical stepwise reduction method. The whole process is to judge, affirm and negate several rounds by analyzing and measuring the parameters, and finally determining the damage of the rectifier tube.

　　2 by law

　　The so-called fiddling law is according to the principle of inverters, along the fault site, along the pathway, step by step, direct fault points, a method to find the fault location.

　　For example, the output voltage of a frequency converter is unbalanced. This fault is obviously caused by 2 possibilities. One possibility is that at least 1 units of the 6 units in the inverter bridge are damaged (open), and the other may be at least 1 groups of damage in the 6 set of driving signals. That has identified 1 inverter units without driving signal, to further determine the position in the driving circuit fault, to find the method to follow it. Specific to this example, can check down, from the source of the driving signal, which is the output of the CPU to play down the investigation.

　　When the CPU output has signal, check the input end of the optocoupler, if there is no signal, then the CPU to the input end of the optocoupler has a broken line phenomenon. If there is a signal, check the output end of the optocoupler and see if the output end of the optocoupler has a signal. If there is no signal, it indicates that the optocoupler is damaged. If there is a signal, then check the input and output terminals of the amplifying circuit. If there is a signal at the input end and no signal at the output terminal, it indicates that the fault occurs in the amplifying circuit or the damage of the amplifying tube or the related components. Then it's easy to implement it further.