As the most mainstream electric control equipment for motor control, frequency converter has many advantages, such as accurate speed regulation, flexible control mode, etc.Although the use method of frequency converter has been familiar with and mastered by the majority of electricians, but the secret of its internal circuit, we may not necessarily understand.Don't believe me to say four this aspect of the content to listen to you:
1. most frequency converters we have seen are three-phase output mode. I'm afraid that many peers will think that three current transformers should be used to detect the current in each phase.The actual situation is that 95% of frequency converters adopt two-phase current detection (of course, there are only two transformers used), and the current value of the remaining one phase is calculated by the two-phase current measured by the frequency converter using the discharge route.
2. in the maintenance or disassembly of the power converter, we do not need to use a multimeter to detect the dc bus voltage, just pay more attention to the inverter internal circuit power indicator on the line.This LED indicator not only displays the power supply normal or not, but also directly reflects the dc bus voltage discharge after power failure (in fact, the filter capacitor voltage), when the lamp is off, the dc bus voltage has been reduced to below 80V, just wait a moment to be assured of follow-up work.
3, the inverter internal switching power supply usually output ±15V, +24V, +5V several voltage levels, among these output voltage is the most important is +5V all the way.Because this circuit voltage is to supply the frequency converter "brain" CPU use, once this circuit voltage appears the fluctuation then the frequency converter inevitably cannot normally run the work!This is why the inverter switching power supply part of the voltage as a monitoring object.
4, because of the operation process of overvoltage, overcurrent and other faults, easily cause the inverter power inverter IGBT/IPM damage, the price of this kind of components is generally more expensive and genuine goods rate is not reliable guarantee.For himself in the process of single-phase small power inverter maintenance through a lot of maintenance instance, found that for single phase 1.5-5.5 KW inverter after the internal damage of IGBT and rectifier bridge, can use two element substitution of induction cooker, as long as the performance is also stable and reliable, reasonable selecting frequency converter and the component prices are relatively cheap, get easier, is a good way to reduce the maintenance cost.