Views:1 Author:Site Editor Publish Time: 2018-04-17 Origin:Site
The selection of energy storage capacitance capacity: the general selection experience value is ≥ 60 μ F / A. For example, the rated current of a 15kW converter is 30A, and the capacitance capacity required is more than 60 μ F / A × 30A or at least 1800 μ F, so four 2200 μ F (two parallel series) or two 4700 μ F capacitors (two series) are generally selected. Of course, we also have to consider the brand of the capacitor, the brand is different, the quality will be very different.
Some people repair the inverter only to the damaged inverter module a change, often do not use how long the module is damaged again. This will complain about the poor quality of the module, poor user environment, and so on. In fact, the most important reason is that they did not find out the cause of the damage to the inverter module, did not thoroughly eliminate the hidden trouble.
The damage of inverter module, in addition to long time overload, poor heat dissipation and lightning impact, the internal reason is that the capacity of capacitors is reduced, lost capacity and failure, which is the fatal killer of the damage. Its harmfulness can not be ignored. When the capacity is reduced, the lighter can be shown as having poor load capacity. When the load is heavier, it often causes the fault of the DC circuit overlooking the gate, and when the capacitance is further damaged, it forms a fatal blow to the inverter module. At this time, the voltage detection circuit has no time to respond. Failure is reported, resulting in damage to the inverter module.
. At this time, the converter DC circuit has completely (or partially) lost the energy storage filtering capacity. DC loop is a pulsating DC with frequency of 300Hz. The current inhaled when the motor starts up increases the pulsating component of the pulsating current. This is one of the reasons why small resistors are bad for high voltage capacitors and large resistors are easy to explode. The distributed inductance and the distributed capacitance in the circuit are added from time to time, and the unfavorable factors are added and acted on each other, which makes the dynamic energy in the circuit rise sharply, and the instantaneous dangerous resonance overvoltage appears at this time! It is also very fragile, and it is not surprising that over-voltage bursts and short-circuits occur. .
But the bad fault of energy storage capacitance is often more hidden, can be said to be a soft fault, easy to be ignored. Some capacitors do not seem to have any problem with their capacity. They can also operate, but they are a major risk in operation. Once again, it is emphasized that: after the energy storage capacitance is lost, resonance overvoltage will easily occur and the module will burst.